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Common loon

The common loon or great northern diver (Gavia immer) is a large member of the loon, or diver, family of birds. Breeding adults have a plumage that includes a broad black head and neck with a greenish, purplish, or bluish sheen, blackish or blackish-grey upperparts, and pure white underparts except some black on the undertail coverts and vent. Non-breeding adults are brownish with a dark neck and head marked with dark grey-brown. Their upperparts are dark brownish-grey with an unclear pattern of squares on the shoulders, and the underparts, lower face, chin, and throat are whitish. The sexes look alike, though males are significantly heavier than females. During the breeding season, loons live on lakes and other waterways in Canada; the northern United States (including Alaska); and southern parts of Greenland and Iceland. Small numbers breed on Svalbard and sporadically elsewhere in Arctic Eurasia. Common loons winter on both coasts of the US as far south as Mexico, and on the Atlantic coast of Europe.

Common loons eat a variety of animal prey including fish, crustaceans, insect larvae, molluscs, and occasionally aquatic plant life. They swallow most of their prey underwater, where it is caught, but some larger items are first brought to the surface. Loons are monogamous; that is, a single female and male often together defend a territory and may breed together for a decade or more. Both members of a pair build a large nest out of dead marsh grasses and other plants formed into a mound along the vegetated shores of lakes. A single brood is raised each year from a clutch of one or two olive-brown oval eggs with dark brown spots which are incubated for about 28 days by both parents. Fed by both parents, the chicks fledge in 70 to 77 days. The chicks are capable of diving underwater when just a few days old, and they fly to their wintering areas before ice forms in the fall.

The common loon is assessed as a species of least concern on the IUCN Red List of Endangered Species. It is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds applies. The United States Forest Service has designated the common loon a species of special status because of threats from habitat loss and toxic metal poisoning in its US range.

The common loon is the provincial bird of Ontario, and it appears on Canadian currency, including the one-dollar "loonie" coin and a previous series of $20 bills. In 1961, it was designated the state bird of Minnesota, and appears on the Minnesota State Quarter.

Taxonomy
The common loon is also known as the great northern diver in Eurasia. (Another former name, great northern loon, was a compromise proposed by the International Ornithological Committee.) It is one of five loon species that make up the genus Gavia, the only genus of the family Gaviidae and order Gaviiformes. Its closest relative is another large black-headed species, the yellow-billed loon or white-billed diver (Gavia adamsii). There are no recognized subspecies of the common loon.

Danish zoologist and mineralogist Morten Thrane Brünnich first described the common loon in 1764, as Colymbus immer in his Ornithologia Borealis. The now-defunct genus Colymbus contained grebes as well as loons, and remained in use until the International Commission on Zoological Nomenclature attempted to clarify the nomenclature in 1956 by declaring Colymbus a suppressed name unfit for further use and establishing Gavia, created by Johann Reinhold Forster in 1788, as the valid genus name for the loons.

The current genus name Gavia was the Latin term for an unidentified seabird and the specific immer is derived from a Norwegian name for the bird, similar to the modern Icelandic word "himbrimi". The word may be related to Swedish immer and emmer: the grey or blackened ashes of a fire (referring to the loon's dark plumage); or to Latin immergo, to immerse, and immersus, submerged.

The European name "diver" comes from the bird's practice of catching fish by diving. The North American name "loon" was first recorded in this sense in New Englands Prospect (1634) by William Wood (1580–1639); "The Loone is an ill shap'd thing like a Cormorant". It may be derived from Old Norse lómr, as are modern Swedish and Danish lom, in each case referring to the distinctive call.

A number of fossil loon species are known from the Pliocene, and specimens from the Pleistocene of California and Florida appear to represent a paleosubspecies of the common loon.

Description
The adult common loon can range from 66 to 91 cm in length with a 127 to 147 cm wingspan, slightly smaller than the similar yellow-billed loon. On average, it is about 81 cm long and has a wingspan of 136 cm. Its weight can vary anywhere from 2.2 to 7.6 kg. Sizes vary regionally, especially by body mass, with the smallest bodied loons on average from lower-central Canada and the Great Lakes, while westerly birds are similar or mildly larger, and loons breeding further east can appear to be significantly larger. Furthermore, males average up to nearly 27% more massive than females in some populations. Breeding loons in Maine averaged 4.65 kg in females and 5.97 kg in males, essentially the same weight as the yellow-billed loon although the yellow-billed is still larger than in linear dimensions (especially bill length) than the Maine loons. In Ontario, 20 females averaged 4.5 kg and 20 males averaged 5.46 kg. In contrast, in the Gulf of Alaska, adults of both sexes reportedly averaged 4.13 kg. Adult breeding plumage consists of a broad black head and neck with greenish, purplish, or bluish sheen. It has a black bill sometimes with a pale tip, and red eyes. The neck is encircled with a characteristic black ring and has two white necklaces of eight to ten short streaks on the upper foreneck, and a noticeable collar of white, parallel lines forming a large oval on the neck-side. The central lower foreneck is pure white, and the lower neck-sides has longitudinal white lines becoming rows of small spots and black lines becoming very narrow. The upperparts are blackish or blackish grey, and each feather has small white spots on it. The upperwing is blackish and with small white spots on the non-primary coverts, whereas the underwing is paler with white coverts except the long black shaft-streaks on the axillaries. The underparts are pure white, but have some black on the undertail coverts and vent. It has a checkered black-and-white mantle and a blackish tail. The legs are pale grey on the inner half and blackish on the outer half, and the webs between the toes are flesh colored.

Adult non-breeding plumage is brownish with a dark neck and head marked with dark grey-brown. The eyes are surrounded with white, and the eyelids are pale. The bill is mostly pale grey, with a dark culmen and tip, but in early spring the tip may turn whitish. The underparts, lower face, chin, and throat are also whitish. The foreneck is whitish, usually forming wedge-shaped notch in dark neck-sides, and may sometimes reveal a shadowy trace of the neck ring or a pale collar. It has dark brownish grey upperparts with an unclear pattern of squares on the shoulders and some wing coverts spotted with white, which are usually concealed while swimming. The male and the female have similar appearances, although they exhibit sexual dimorphism in their physical dimensions with the male larger and significantly heavier than the female.

The heavy dagger-like bill is evenly tapered and greyish, sometimes having a black tip. The bill colour and angle distinguish this species from the yellow-billed loon. The neck is short and thick. It swims very low in the water, with sometimes only its head held above and horizontal to water. It must run across the water surface to get in flight. During flight, its head is slightly lower than its body, with its feet trailing behind. It has a skeletal structure made up of a number of solid bones (this is usual for the Gaviiformes and penguins but unlike most flying birds which have bones with extensive pneumatization, hollow and filled with air to make the skeleton lighter), which adds weight but helps in diving. A juvenile often has a dark, brownish-grey nape that may look darker than the pale-edged black feathers. It has a dark grey to black head, neck, and upperparts, with white throat, cheeks, and underparts. During the first winter, the bill shape of the young may not be as fully developed as that of the adult, and during the second winter, it much resembles the breeding adult, but with wing coverts lacking white spots.

The common loon is distinguished from the black-throated loon (G. arctica) and the red-throated loon (G. stellata) mainly by its larger size. It usually has a steeper forehead and a bulging forecrown, somewhat similar to the black-throated loon. Its bill is heavier and the back is paler than its hindneck. It is more difficult to separate from the yellow-billed loon, but its breeding plumage has more white markings on the neck and the squares on its shoulders are usually smaller; the non-breeding plumage has darker neck-sides contrasting more sharply with pale areas and bill colour.

Moult
The scaly juvenile plumage is retained until January or February of the year following hatching, when a lengthy moult of head and body feathers gives them a more adult-like appearance. Adults shed all their flight feathers simultaneously around this time, leaving them temporarily flightless, prior to gaining breeding plumage, but second-year birds delay this substantial moult until the summer. The adult winter plumage is attained between October and January by partial moult mainly of head, body and tail feathers.

Genomics
With improved gene-sequencing technology, a draft genome of the common loon has assembled and identified at least 14,169 common loon genes. 80.7% of chicken genes are found in the common loon genome. The physiological costs of deep-water diving and long distance aerial migration of loons have greatly affected loon evolution. Many identified genes are candidate genes for positive selection since the common loon-chicken split 90 million years ago. It is theorized that these candidate genes are related to hemoglobin affinity for oxygen, solute exchange, immunoglobulin function related to immune defense, nervous system development and a number of molecular pathways related to DNA metabolic function, and G-receptor pathways potentially involved in low-light visual acuity. For example, SLC48A, and SLC20A1 are candidate genes in the Gavia lineage for maintaining homeostasis due to maybe having a role in maintaining ion and pH balance.

Distribution and habitat
Common loons are mainly Nearctic, and breed from 48° N to the Arctic Circle, locally south to 40° N and north to 78° N. During their breeding season in spring and summer, most common loons live on lakes and other waterways in the northern United States and Canada, as well as in southern parts of Greenland, in Iceland, in Svalbard, in Jan Mayen, and in Bear Island in Norway; and in Alaska, to the west, and very rarely in Scotland, to the east. Their summer habitat ranges from wooded lakes to tundra ponds. The lakes must be large enough for flight take-off, and provide a large population of small fish. Deep lakes with warm surface waters, relatively low biological productivity and low turbidity where their fish prey are easy to see are habitats where breeding loons are more successful in raising young. For protection from predators, common loons favour lakes with islands and coves. They are rare visitors to the Arctic coast. They are known to exhibit high breeding site fidelity. Some common loons remain in Iceland year-round, although most migrate. In North America, they winter mainly along north Atlantic and north-east Pacific coasts, many stopping off on the Great Lakes during their migration. They migrate in the day, starting about two hours after sunrise and flying at altitudes of 1500 to 2700 m above sea level, above the convective and turbulent layer of air. In winter they can be seen on North America coasts as far south as Baja California, Sonora, northern Sinaloa, southern Texas, and rarely northern Tamaulipas. In the east, several thousand winter along western European coasts, probably originating from Iceland, Greenland, and Canada. Their range extends into northwestern Europe from Finland to Portugal and southern and northwestern Spain (Galicia and Asturias), as well as the western Mediterranean off Catalonia, and off Morocco in Africa, although only a few hundred travel as far south as Iberia. Although wintering site fidelity is not well known, annually, adults are observed to return to the same wintering locations in the Pacific Ocean (Morro Bay), the Gulf of Mexico (Barataria Bay), the Atlantic Ocean (Maryland and Massachusetts), and the reservoir Lake Pateros.

They usually winter along coasts and on inland lakes, bays, inlets, and streams, with birds migrating to the nearest body of water that will not freeze over in the winter: western Canadian loons go to the Pacific, Great Lakes loons to the Gulf of Mexico region, eastern Canadian loons to the Atlantic, and some loons to large inland lakes and reservoirs. They appear in most of the inland waters of the United States. The South Carolina coast, the Gulf coast adjacent to the Florida panhandle, and the Atlantic seaboard from Massachusetts to Maine have some of the highest concentrations of common loons. Occasional vagrants are recorded inland in Mexico, in San Luis Potosí and Coahuila, as well as in Chiapas and Oaxaca in the south. They are accidental in northern Japan and the Commander Islands in northwestern Pacific, and Cuba in the West Indies.

Behaviour
The common loon is an expert fisher, catching its prey underwater by diving as deep as 60 m. With its large webbed feet, the common loon is an efficient underwater pursuit predator and adroit diver. It needs a long run-up distance to gain momentum for flight take-off and is ungainly on land, sliding on its belly and pushing itself forward with its legs. Its clumsiness on land is due to the legs being positioned at the rear of its body; the pelvic muscles are well developed, ideal for swimming but not well-suited for walking. When it lands on water, it skims along on its belly to slow down, rather than braking with its feet, as they are set too far back. The common loon swims and dives well, and flies competently for hundreds of kilometres in migration. It flies with its neck outstretched, usually calling a particular tremolo that can be used to identify a flying loon. Its flying speed is as much as 120 km/h during migration. Particularly during the breeding season, common loons frequently engage in territorial disputes against other water birds, including ducks and geese, and will attack or drive off competitors and intruders to their territory.

Feeding
Fish account for about 80% of the diet of the common loon. It forages on fish of up to 26 cm in length, including minnows, suckers, gizzard shad, rock bass, alewife, northern pike, whitefish, sauger, brown bullhead, pumpkinseed, burbot, walleye, bluegill, white crappie, black crappie, rainbow smelt, and killifish. The young typically eat small minnows, and sometimes insects and fragments of green vegetation. The freshwater diet primarily consists of pike, perch, sunfish, trout, and bass; the saltwater diet primarily consists of rock fish, flounder, sea trout, herring, Atlantic croaker, haddock, and Gulf silverside. When there is either a lack of fish or they are difficult to catch, it preys on crustaceans, crayfish, snails, leeches, insect larvae, molluscs, frogs, annelids, and occasionally aquatic plant matter such as pondweed, roots, moss, willow shoots, seeds, and algae. It has also been known to eat ducklings.

The common loon uses its powerful hind legs to propel its body underwater at high speed to catch its prey, which it then swallows head-first. If the fish attempts to evade the common loon, the bird chases it down with excellent underwater manoeuvrability due to its tremendously strong legs. Most prey are swallowed underwater, where they are caught, but some larger prey are first brought to the surface. It is a visual predator, so it is essential to hunting success that the water is clear. It normally dives 4 to 10 m, but has been recorded to dive up to 70 m. The average diving time is 42 seconds, but the maximum duration spent underwater is about 1 minute.

Breeding
The common loon's mating system is serially monogamous; breeding pairs jointly defend a territory consisting of an entire small lake or a protected bay within a large lake. A given male and female remain together throughout a breeding attempt, rear their own biological offspring, reunite each spring, and may breed together for many consecutive years. However, in the event of death or territorial eviction of one pair member by an intruding loon of the same sex, the other pair member quickly establishes a pair bond with the evicting bird. (Hence, most adult loons have two or more different mates during their lives.) Evicting individuals tend to be young males and females (5 to 9 years old), while evicted adults are often those 15 years and older.

Pairs do not remain together during winter; in addition, males usually precede females by a few days to a few weeks during spring migration, settling on their lake once a portion of it becomes ice-free. Copulation takes place ashore, often on the nest site, repeated daily until the eggs are laid. The preceding courtship is very simple, with mutual bill-dipping and dives. The displays towards intruders, such as bow-jumping (an alternation of fencing and bill-dipping postures and rushing (running "along the surface with its wings either folded or half-extended and flapping at about the same speed as when taking off" ) are often misinterpreted as courtship.

Nesting typically begins in early May. Significantly more nesting sites are found on islands than on mainland shoreline. Breeding pairs patrol their territories routinely, even at night, defending the territory both physically and vocally. Pairs that nested together the preceding year typically reuse the nest site from the previous year, if they hatched chicks successfully there. In contrast, pairs that lost their eggs to a predator usually shift the nest to a new location. This logical behaviour pattern appears to depend upon the male, because breeding pairs consisting of last year's male and a female not present during the preceding year continue to exhibit the behaviour; pairs composed of last year's female and a new male tend to select a new nest site, regardless of the success or failure of the previous year's attempt. Despite the lead role of males in nest site selection, both sexes contribute substantially to nest construction. The nest is about 56 cm wide and is constructed out of dead marsh grasses and other indigenous plants, and formed into a mound along the vegetated coasts of lakes greater than 3.7 ha. After a week of construction in late spring, one parent climbs on top to mold the interior of the nest to the shape of its body. Based on a number of studies, nesting success averages about 40%, and most newly hatched young survive due to parental care.

Eggs from first clutches are typically laid in May or early June, the timing depending largely upon the date that lakes become ice-free and inhabitable. A clutch consists of two (occasionally one) olive-brown oval eggs with dark brown spots. Incubation is carried out jointly by male and female and lasts about 28 days. Loons often place nests along steep lake shorelines where adults can quickly dive underwater when approached by predators. The eggs are about 88 mm long and 55 mm wide and the two eggs are laid with an interval of one to three days between them, and hatch asynchronously.

Newly hatched chicks are dark chocolate brown in color and have a white belly. Within hours of hatching, the young begin to leave the nest with the parents, swimming close by and sometimes riding on one parent's back. Parents and chicks initially stay in shallow, isolated bays where the parents are able to defend the chicks better from intruding loons and eagles, which are their main predators. Male parents defend broods consisting of two chicks more vigorously than singleton chicks, chiefly with the territorial yodel call. The chicks are capable of making shallow dives from their first day but make deeper dives as they grow. Fledging takes 70 to 77 days. Usually, only one brood is raised. Both parents feed the chicks live prey from hatching to fledging. As they grow, chicks are able to catch an increasingly large proportion of their diet by themselves; they can feed and fend for themselves after about two months, although many juveniles continue to beg from adults well beyond this age. The parent birds capture small fish and hold them crosswise in their bill, call and approach the chicks with their head lowered so that the chicks can grasp them. If food is scarce, the larger chick may peck its small sibling incessantly; on small lakes with limited food, only one chick often survives. Juveniles leave the breeding ground before ice formation in the fall, weeks after their parents. A pair of loons raising two chicks have been estimated to feed on 423 kg of fish during the five and a half months that they spend in their breeding territory.

Habitat selection
Loons exhibit a strong tendency to settle as breeders on a lake that resembles their natal one, a phenomenon termed natal habitat imprinting. This preference is based on two lake attributes: size and pH. The behaviour is puzzling, because it is as strong in loons hatched on small, acidic lakes as those from large lakes of neutral pH. Hence, the former group is exhibiting active preference for lakes that have been shown to result in higher chick mortality and lower breeding success.

Vocalizations
The common loon produces a variety of vocalizations, the most common of which are the tremolo, the yodel, the wail, and the hoot. Each of these calls communicates a distinct message. The frequency at which it vocalizes has been shown to vary based on time of day, weather, and season. It is most vocally active between mid-May and mid-June. The wail, yodel, and tremolo calls are sounded more frequently at night than during the day; calls have also been shown to occur more frequently in cold temperatures and when there is little to no rain.

The tremolo call—sometimes called the "laughing" call—is characterized by its short, wavering quality. It often uses this call to signal distress or alarm caused by territorial disputes or perceived threats. It emits a tremulous series of up to 10 rather high notes (hu)-heheheheheheha. It also uses the tremolo to communicate its presence to other loons when they arrive at a lake, often when they are flying overhead. It is the only vocalization used in flight. The tremolo call has varying three levels of intensities that correlate with a loon's level of distress, and the types are differentiated by increasingly higher pitch frequencies added to the call.

The yodel is a long and complex call made only by the male. It is used in the establishment of territorial boundaries and in territorial confrontations, and the length of the call corresponds with the loon's level of aggression. The dominant frequencies in the yodel indicate the body mass and thereby the health of males. A male that occupies a new territory appears to alter its yodel to be clearly distinguishable from the call of the previous territory owner.

A loon's wail is a long call consisting of up to three notes, and is often compared to a wolf's howl. It uses this call to communicate its location to other loons. The call is given back and forth between breeding pairs or an adult and its chick, either to maintain contact or in an attempt to move closer together after being separated. It is a loud aaoo, weee-wea weee-wea weee-wea, or ooo-aaah-éééé.

The hoot is a short, soft call and is another form of contact call. It is a more intimate call than the wail and is used exclusively between small family groups or flocks. The common loon hoots to let other family or flock members know where it is. This call is often heard when the adult loon is summoning its chicks to feed.

Longevity and terminal investment
Considerable information on longevity and survival rates has been collected in the past two decades, owing to the implementation of an efficient capture protocol that permits marking and monitoring of large study populations. A rough preliminary analysis showed that common loons of both sexes survive at an annual rate of over 90% until they reach their mid-20s, but show a survival rate of only about 75% thereafter. However, a second, finer-scaled analysis made clear that male loons begin to show higher mortality, increased territory loss and lower body condition starting at age 15. Perhaps in response to their physical decline, males 15 and older show increased rates of both territorial aggression and territorial vocalization. This age-related shift in behaviour is interpreted as terminal investment, a "go for broke" strategy seen in senescing animals that are attempting to eke out another year or two of breeding before they die.

Predators and parasites
Adult common loons have few predators, although bald eagles will attack incubating birds. Attacks by sharks in winter have also been recorded. When a predator approaches (either the loon's nest or the loon itself), the common loon sometimes attacks the predator by rushing at it and trying to stab it with its dagger-like bill, aiming its attacks either at the predator's abdomen or the back of its head or neck, which may be deadly to predators up to the size of a fox or raccoon.

Eggs are taken by a number of mammals, including American mink, striped skunk, otters, foxes and raccoons, with the latter being responsible for nearly 40% of all nest failures. Birds such as herring gulls, northern ravens and American crows will eat unattended eggs. Because their nests are at the water's edge, common loon eggs are especially vulnerable if the adult is absent.

Chicks may be killed by common snapping turtles, large gulls, bald eagles and large fish such as northern pike and largemouth bass. The eagle in particular is a significant predator of chicks.

Internal parasites of the common loon include many species of worms, including flatworms, tapeworms, nematodes and spiny-headed worms. High levels of worms may result from feeding changes due to low availability of fish, and can lead to illness and death. Protozoal infections including one caused by Eimeria gaviae and avian malaria have been recorded in this loon. The black fly Simulium annulus is closely associated with the common loon to which it is attracted to chemicals in the uropygial gland secretions as well as by visual and tactile cues. This fly is detrimental to loons, their preferred hosts, transmitting blood-borne parasites and viruses, and causing nest abandonment when numbers are high. External parasites include ischnoceran feather lice, although these are not found on the bird's head.

Botulism, acquired by eating infected fish, can lead to paralysis and drowning. Aspergillosis is another cause of emaciation and death. Outbreaks sometimes lead to thousands of deaths.

Status and conservation
Since 1998, the common loon has been rated as a species of least concern on the IUCN Red List of Endangered Species. This is because it has a large range – more than 20000 km2 – and because it has a stable population trend that does not warrant a vulnerable rating. It also has a large population size of 612,000 to 640,000 individuals. The estimated breeding population ranges from 1,400 to 2,600 mature individuals in Europe. Over half of the breeding population in North America is found in Ontario with 97,000 territorial pairs, and in Quebec with 50,000 territorial pairs. About 2,400 individuals occur in each of the maritime provinces of Canada—Nova Scotia and New Brunswick. British Columbia accounts for 25,000 territorial pairs. In far northern Canada, about 50,000 territorial pairs are known to occur, and 12,500 to 15,000 territorial pairs occur in the Prairie Provinces of Alberta, Manitoba, and Saskatchewan. In the United States, the largest breeding population is present in Alaska with 3,600 to 6,000 territorial pairs. The U.S. Great Lakes region has 5,900 to 7,200 territorial pairs which accounts for over half of the breeding population in the United States. There are about 100 territorial pairs in the northwestern U.S. states of Washington, Idaho, Montana, and Wyoming. About 2,250 territorial pairs are found in New England and New York. In winter, 3,500 to 4,500 individuals are found in the United Kingdom, and even fewer individuals are found in the western European coastline and in Iceland. Along the Pacific Coast, about 184,000 to 189,000 adults and 31,000 to 32,000 juveniles are found, and along the Atlantic Coast, 423,000 to 446,000 adults and 72,000 to 76,000 juveniles are found.

The common loon is listed under Appendix II of the Convention on the Conservation of Migratory Species, and in Article I under the European Union (EU) Birds Directive. It is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) is applied. In Europe it appears in 20 Important Bird Areas (IBAs), including Ireland, Svalbard, mainland Norway, Iceland, Spain, and the United Kingdom. It is also a listed species in 83 Special Protection Areas in the EU Natura 2000 network. The USDA National Forest Service has designated the common loon a species of special status, and in the upper Great Lake regions of the Huron-Manistee, Ottawa, and Hiawatha national forests as a regional forester sensitive species.

Effects of mercury and acid rain pollution on health and brood productivity
The common loon is a key indicator of mercury deposition in aquatic environments due to its position at the top of the food chain. The main contributors to elevated mercury concentrations in aquatic environments are coal burning power plants, waste incineration, and metal production. Although environmental mercury (Hg) is naturally occurring, methylmercury (MeHg) is a biologically toxic form that accumulates throughout aquatic environments in the northeastern United States. Methylmercury, a neurotoxin, has been shown to have a wide range of behavioral, reproductive, and survival effects on the common loon. Previous research has found a correlation between mercury levels and pH, with more acidic aquatic environments being at the highest risk for elevated methylmercury concentrations. Once mercury enters the water, it is taken up by fish and spread throughout the food chain. Resulting from this transmission of mercury, there is a significant positive correlation between mercury levels in fish and mercury levels in male, female, and chick blood of common loons; consequently, an increase in mercury concentration in the blood of common loons and fish was seen with a decrease in local aquatic pH. Although there have been reductions in recent years in acidifying emissions, there has been limited biological recovery in these lakes most likely due to climate change. Research has shown that warmer summer temperatures can inhibit reestablishment of cold-water fish species in acidified lakes and droughts brought on by increased summer temperatures can further acidify lakes.

Although the common loon are able to decrease their methylmercury levels by molting and laying eggs, continued consumption of fish with raised methylmercury levels prevents these mechanisms from effectively lowering methylmercury levels. Mercury concentrations have been shown to vary by the sex and age of common loons. Male common loons were found to contain the highest blood mercury concentration likely due to the fact that they tend to consume bigger fish with higher mercury concentrations. Females contained the second highest blood mercury concentration with differences between the males likely being due to the fact that females can expel mercury into the eggs they lay. Juveniles had the lowest blood mercury concentration. Scientists found that the data from juveniles helped to best indicate the local mercury availability as they are fed exclusively from their natal territory.

Elevated levels of mercury have been associated with changes in foraging and brooding behavior among adult common loons, especially in higher concentrations. Studies have found that elevated levels of methylmercury are associated with lethargy and decreased time spent foraging in adult common loons. A different study carried out in the Adirondack Mountains found that elevated levels of methylmercury are associated with reduced diving frequency in adult common loons. One study found that brood productivity was reduced by half when female blood mercury levels exceeded 4.3 μg/g and productivity completely failed when female blood mercury levels exceeded 8.6 μg/g. These results are related to fish mercury levels of 0.21 μg/g and 0.41 μg/g, respectively. As mercury levels and pH are correlated, scientists have found that brood success decreases with decreasing pH such that environments with a pH at around 4.5 exhibited reproductive success below a calculated positive growth rate threshold. An association has also been observed between elevated blood methylmercury levels and aberrant incubation patterns. Adult common loons with high levels of methylmercury were found to spend less time incubating and in the nest, increasing the risks of predation and the eggs overheating/overcooling. Together, the effects of heightened methylmercury levels on parenting behaviors may contribute to lower chick survival rates. One study in Maine and New Hampshire found that high levels of methylmercury in parents are associated with a significant decrease in the number of fledged young, with common loons in the highest risk group producing 41% fewer fledged young than common loons with low levels of methylmercury.

Mercury deposition in the Adirondack Mountains
The common loons of the Adirondack Mountains are particularly affected by methylmercury as the acidity of the lakes provides an environment conducive to converting environmental mercury to methylmercury. One study found that 21% of the male Adirondack common loon and 8% of the female Adirondacks common loon sampled were at high risk for detrimental impacts such as behavioral and reproductive abnormalities. In the Adirondacks, bioaccumulation factors for methylmercury were found to increase up the food chain, leaving common loons at the highest risk for detrimental effects from methylmercury. Spatial analysis indicates that the highest aquatic mercury concentrations are found in the southwestern portion of the Adirondacks, an area with lakes heavily affected by acid rain. Organizations such as the Adirondack Loon Center and the Adirondack Cooperative Loon Program spearhead loon conservation efforts in the Adirondacks by performing research, engaging the public, and informing public policy.

Breeding range decline
The common loon's breeding range has moved northward, the species breeding as far south as Iowa a century ago. It too is adversely affected by acid rain and pollution, as well as lead poisoning from fishing sinkers (especially those that are about the size of the grit stones they ingest ) and mercury contamination from industrial waste. Heavy metals such as mercury may be partially removed through biological processes such as excretion or deposition in feathers, but their adverse effects are magnified through concentration of the toxic elements in organs such as the liver. Eggs shells may also contain metal contaminants, leading to low reproductive productivity. High levels of heavy metals are linked to loons being in poor condition, males being affected more because they eat larger fish.

The common loon has also faced a decline in breeding range due to hunting, predation, and water-level fluctuations, or flooding. Some environmentalists attempt to increase nesting success by mitigating the effects of some of these threats, namely terrestrial predation and water-level fluctuations, through the deployment of rafts in the loon's breeding territories. In addition, artificial floating nesting platforms have been provided for the common loon in some lakes to reduce the impact of changing water levels due to dams and other human activities. The common loon abandons lakes that fail to provide suitable nesting habitat due to shoreline development. It is endangered by personal water-craft and powerboats that may drown newly born chicks, wash eggs away, or swamp nests. It is still considered an "injured" species in Alaska as a result of the Exxon Valdez oil spill.

Lead poisoning
In a 2003 survey of New England dead loons, lead poisoning from fishing weights accounted for about half of the deaths, and other human factors directly caused the death of 52% of the observed 522 loons.

In culture

The common loon appears on Canadian currency, including the one-dollar "loonie" coin and the previous series of $20 bills. It is the provincial bird of Ontario. It was designated the state bird of the U.S. state of Minnesota in 1961, and also appears on the Minnesota State Quarter.

Folklore
The voice and appearance of the common loon has made it prominent in several Native American tales. These include an Ojibwe story of a loon that created the world, and a Mi'kmaq saga describing Kwee-moo, the loon who was a special messenger of Glooscap (Glu-skap), the tribal hero. The tale of the loon's necklace was handed down in many versions among Pacific Coast peoples. The Delaware in the east of North America and the Buryats of Siberia also had creation stories involving the loon.

Folk names for the common loon include "big loon", "call-up-a-storm", "greenhead", "hell-diver", "walloon", "black-billed loon", "guinea duck", "imber diver", "ring-necked loon", and "ember-goose". An old colloquial name from New England was call-up-a-storm, as its noisy cries supposedly foretold stormy weather. Some old Scottish names such as arran hawk and carara are corruptions of old Scottish Gaelic onomatopoeic names representing the bird's call; others, like bishop and ember goose, were used to avoid older names for this sometimes ill-omened bird.

The common loon was eaten in the Scottish Islands from the Neolithic until the eighteenth century, and its thick layer of fat beneath the skin was used as a cure for sciatica.

Popular culture
The bird is central to the plot of the children's novel Great Northern? by Arthur Ransome (in which it is referred to throughout as "great northern diver", with the then current scientific name Colymbus immer). The story is set in the Outer Hebrides, where the main characters—a group of children on holiday—notice a pair of divers apparently nesting there. Checking their bird book, they believe that these are great northern divers. However, these have not previously been seen to nest in northern Scotland, and so they ask for help from an ornithologist. He confirms that these birds are indeed the great northern; unfortunately, it soon transpires that he does not wish merely to observe, but wants to steal the eggs and add them to his collection; and to do this, he must first kill the birds. Published in 1947, the story is one where the conservationists are the eventual victors over the egg collector, at a time when the latter hobby was not widely considered to be harmful.

Major League Soccer club Minnesota United FC uses the loon in its crest and nickname, as well as a mascot.

Films
The wailing call of the loon is widely used in film and television to evoke wilderness and suspense, and is referenced in songs such as "Old Devil Moon" ("wanna laugh like a loon").

Loons are featured prominently in the 1981 film On Golden Pond. Its distinctive sound also appeared in Conan the Barbarian, Out of Africa, Platoon, Guinevere, Harry Potter and the Prisoner of Azkaban, Rick and Morty, Watchmen, Godzilla, Kubo and the Two Strings, Avengers: Infinity War, Pet Sematary, 1917 and Avengers: Endgame, among others.

In the 2016 Pixar movie Finding Dory, a somewhat bedraggled and dimwitted loon named Becky is persuaded to use a bucket to help two of the main characters, Nemo and Marlin, get into a marine life institute where the titular Dory is trapped.

title: Common loon


text:
Subdeacon

Subdeacon is a minor order of ministry for men in various branches of Christianity. The subdeacon has a specific liturgical role and is placed below the deacon and above the acolyte in the order of precedence.

Subdeacons in the Eastern Orthodox Church
A subdeacon, also called hypodeacon, is the highest of the minor orders of clergy in the Eastern Orthodox Church. This order is higher than the reader and lower than the deacon.

Canonical discipline
Like the reader, the clerical street-dress of the subdeacon is the cassock, which is usually black but only need be so if he is a monk. This is symbolic of his suppression of his own tastes, will, and desires, and his canonical obedience to God, his bishop, and the liturgical and canonical norms of the Church. As a concession in countries where Eastern Orthodoxy is little known, many only wear the cassock when attending liturgies or when moving about the faithful on church business. In some jurisdictions in the United States, a clergy-shirt will sometimes be worn instead of a cassock, and is commonly worn buttoned but with no collar or collar-tab to indicate a rank lower than deacon.

There is a special liturgy for the tonsuring of a subdeacon, although in contemporary practice an acolyte or a reader may receive the bishop's blessing to vest and act as a subdeacon generally or for a particular occasion if there is no subdeacon available. This situation often arises if there is a need for a subdeacon and a likely candidate has stated an intention to marry but has not yet done so, causing a delay in his ordination. The reason for this lies in the fact that the canons prohibit subdeacons to marry after their ordination (just like deacons and priests). This latter stipulation has led, in some places, to the reservation of the formal ordination liturgy as a stepping-stone for candidates for the priesthood, although this is by no means universal. It also means that, while teenagers who show particular fervour may be ordained as acolytes and readers, the subdiaconate is usually reserved for those of more mature years; the canonical minimum age for subdiaconal ordination is twenty years.

A custom in some jurisdictions is that former seminarians who have discerned not to have a calling to the priesthood or diaconate, are, if they wish (and provided that they are married, or being unmarried, do not intend to marry), ordained subdeacons as a sign of investment, faith, and to award their service.

Byzantine Rite
In the Byzantine Rite (followed by the majority of Eastern Orthodox churches) the subdeacon's liturgical role is primarily that of servant to the bishop. He assists the bishop during hierarchical liturgies, (at which a hierarch/bishop is present and presiding) by vesting him, by looking after and presenting the trikiri and dikiri, placing the aëtos, operating the veil and Royal Doors, and handing the bishop and relieving him of all that he needs so as to enable him to perform his role of prayer undistracted. Outside of hierarchical liturgies, the subdeacon serves in the altar as any other server but, as highest-ranking of the minor clergy, is responsible for co-ordinating and leading the serving team. In addition to the above duties, the subdeacon may read the reading from the Epistle at the Divine Liturgy if there is only one deacon. The subdeacon also has practical responsibilities in the care of the altar, by cleaning it, looking after the clergy vestments and the cloths of the Holy Table, cleaning and mending them, and changing them according to the feasts, fasts, and seasons. For this reason, he has a general blessing to touch the Holy Table and the Table of Oblation, which Readers and other servers may not do. He is also responsible for the training of new servers.

The clerical street-wear of a subdeacon is the inner-cassock (podryasnik) and outer cassock (ryasa). Many wear the cassock only when present among the church community or attending to church business.

For liturgies, the subdeacon is vested in a sticharion with an orarion tied around his waist, up over his shoulders (forming a cross in back), and with the ends crossed over, and tucked under the section around the waist. This distinguishes them from acolytes in those jurisdictions where acolytes are ordained and blessed to wear the orarion, as the latter do not wear the orarion crossed in front but simply hanging straight down.

The ordination to the subdiaconate is performed outside of the altar and in a context other than the Divine Liturgy. The reader who is to be tonsured subdeacon is presented to the bishop by two other subdeacons, who first lead him to the nave. There he faces east and makes a prostration before turning to make three prostrations towards the bishop, moving further west after each one. He is then led to stand immediately before the bishop. The subdeacons present the orarion to the bishop, who blesses it. The ordinand then kisses the orarion and the bishop's hand, and the subdeacons vest the ordinand in the orarion.

The bishop blesses the ordinand three times with the sign of the Cross upon his head, then lays his right hand upon the ordinand's head and prays the prayer of ordination. The new subdeacon kisses the bishop's right hand and makes a prostration before the bishop, after which the more senior subdeacons drape a towel over his shoulders and present him with a ewer and basin, with which he washes the bishop's hands after the usual manner. The bishop dries his hands and the three subdeacons receive the bishop's blessing and kiss his hands.

The senior subdeacons return to the altar while the new subdeacon, still holding the ewer and basin, stands on the soleas, facing the icon of the Mother of God and saying particular prayers quietly. The Sixth Hour is completed and the Divine Liturgy continues as usual. The subdeacon remains on the soleas until the Cherubikon, when he and two senior subdeacons wash the bishop's hands as usual.

At the Great Entrance, the new subdeacon joins on the very end of the procession, carrying the ewer and basin and, after the commemorations, takes the blessed water to the people so that they may bless themselves with it.

On occasions when there is a shortage of altar servers, the newly ordained subdeacon may be required to serve at the Liturgy, in which case the taking of the blessed water to the people may be omitted, and he may be asked not to stay on the soleas but rather to assist with serving duties in the altar and at the entrances.

The Western Rites
In the Western Rite, the subdeacon's role is essentially as an assistant to the deacon in performing his diaconal role. This perhaps more clearly reflects the origins of the subdiaconate than in the Byzantine Rite, where, rather than the subdeacon assisting the deacon, many formerly diaconal functions have, over time, come to be seen as properly belonging to the subdeacon in his own right. In the Western Rite, the subdeacon is charged with reading the epistle at a High Mass (the most solemn and elaborate form of the western Eucharist) – a role that may be performed by a priest or reader at a simpler form of the mass, and with assisting the deacon with the preparation of the oblations and with carrying them to the altar, (in those western rites that retain the Offertory Procession). He also assists the deacon during the reading of the Gospel by carrying the Gospel book to and from (depending on the rite used) the place of proclamation, and by acting as a support for the book while the Gospel is read. At pontifical liturgies (at which a pontiff or bishop is present and presiding), the subdeacon also assists the deacon in the vesting of the bishop.

The usual street-wear of the subdeacon is the cassock. (There is no distinction between an inner and outer cassock in the Western Rite, and all clergy wear one cassock only).

During liturgies, the subdeacon vests in an alb, over which he wears the maniple, the cincture, and the tunicle. Unlike his brother subdeacons in the Byzantine Rite who wear the orarion, the subdeacon does not wear its western equivalent - the stole - which is reserved for deacons, priests, and bishops.

Latin Church
Prior to the reform instituted by Pope Paul VI with his motu proprio Ministeria quaedam of 15 August 1972, the subdiaconate was regarded as the lowest of the major orders of the Latin Church. He decreed that "the major order of subdiaconate no longer exists in the Latin Church" and that the functions previously assigned to the subdeacon are now entrusted to the acolyte and the lector; he also decreed that, where the local episcopal conference so desired, the acolyte could be called a subdeacon.

The traditional rites of ordination to the subdiaconate and the minor orders (those of acolyte, exorcist, lector and porter) are still employed for members of certain Catholic religious institutes and societies of apostolic life authorized to use the extraordinary form of the Roman Rite.

As men in major orders, subdeacons, like deacons, were styled in English-speaking countries as "The Rev. Mr." In French the title of Abbé was often given to them and even to those in minor orders, as in the case of Franz Liszt.

The subdiaconate was generally considered a major order in the Latin church from the late 12th century. After that, ordination of a subdeacon did not include the laying on of hands. Instead, the bishop handed to him an empty chalice and paten, his vestments, cruets of wine and water, and the Book of the Epistles and pronounced a prayer of blessing for him. As a recipient of a major order, a subdeacon could not contract marriage, and any breach by him of the obligation to observe celibacy was classified as a sacrilege (cf. canon 132 of the 1917 Code of Canon Law). Canon 135 of the same Code of Canon Law obliged him to say all the canonical hours of the Divine Office (Liturgy of the Hours or Breviary).

The other major orders were those of the deacon and priest, that of bishop not being then considered an order distinct from that of priesthood. Thus, in speaking of orders, the Catechism of the Council of Trent declares : "Their number, according to the uniform and universal doctrine of the Catholic Church, is seven, Porter, Reader, Exorcist, Acolyte, Sub-deacon, Deacon and Priest. [...] Of these, some are greater, which are called 'Holy', some lesser, which are called 'Minor Orders'. The great or Holy Orders are Sub-deaconship, Deaconship and Priesthood; the lesser or Minor Orders are Porter, Reader, Exorcist, and Acolyte".

Today the Latin Church, as stated in the Code of Canon Law in force since 1983 ("The orders are the episcopate, the presbyterate, and the diaconate"), recognizes only three orders, those of bishop, priest (presbyter) and deacon, also referred to as "sacred orders" or "holy orders". In line with Pope Paul VI's Ministeria quaedam, what were called minor orders are now called ministries.

In the Solemn High Mass form of Tridentine Mass and the Ordinariate Mass, the duties of a subdeacon included those of crucifer, singing the Epistle, holding the Book of Gospels while the deacon sings the Gospel, carrying it back to the celebrant afterwards and assisting the priest or deacon in setting the altar. Although the subdeacons were allowed to carry out numerous functions specific to the diaconate, however they were always precluded from distributing Communion, in the form of both bread and wine. The subdeacon's specific vestment is the tunicle, in practice almost indistinguishable in form from the deacon's dalmatic (the tunicle is sometimes somewhat longer than the dalmatic or had slightly less elaborate decoration, but this is often unnoticeable by the casual church-goer). Unlike deacon and priest, he never wears a stole. In the former Mass rites he wore a maniple and also wore a humeral veil while holding the paten from the Offertory to the Our Father; and, if the chalice and paten with host are not already on the altar, he also used the humeral veil when bringing these to the altar at the Offertory. In practice, the roles of deacon and subdeacon in Solemn High Mass were generally performed by men already ordained as priests, wearing the subdiaconal or diaconal vestments. The Personal Ordinariate of the Chair of Saint Peter uses instituted acolytes in the role of subdeacon, but also uses men ordained as priests or deacons for the subdiaconal role.

Eastern Catholic Churches
In the Eastern Catholic Churches which use the Byzantine Rite, the order of subdeacon is the highest of the minor orders and its functions are equivalent to those of Orthodox subdeacons.

Subdeacons in the Anglican Church
Whilst the office of subdeacon was not included in the Orders of Clergy when the Church of England was established during the 16th century, certain churches and communities in the Anglican Communion and within the Anglican Continuing Churches assign a layperson to act as subdeacon in the celebration of the liturgy of the Holy Communion (especially Solemn High Mass). However, this is considered a liturgical function one fulfills and not an order to which one is ordained. In some dioceses and provinces, laypersons who act as subdeacons in this manner may be required to be specifically authorised by the respective bishop or archbishop. In practice, an Anglican subdeacon performs similar roles to those performed in Latin Catholic or Western Rite Orthodox churches. The proper garments of the subdeacon are the alb and tunicle.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Subdeacon


text:
Ningxia

Ningxia, officially the Ningxia Hui Autonomous Region, is an autonomous region in Northwestern China.

Formerly a province, Ningxia was incorporated into Gansu in 1954 but was later separated from Gansu in 1958 and reconstituted as an autonomous region for the Hui people, one of the 56 officially recognised nationalities of China. Twenty percent of China's Hui population lives in Ningxia.

Ningxia is bounded by Shaanxi to the east, Gansu to the south and west and Inner Mongolia Autonomous Region to the north and has an area of around 66400 km2. This sparsely settled, mostly desert region lies partially on the Loess Plateau and in the vast plain of the Yellow River and features the Great Wall of China along its northeastern boundary. Over about 2000 years, an extensive system of canals (with a total length of approximately 1397 kilometers) has been built from Qin dynasty. Extensive land reclamation and irrigation projects have made increased cultivation possible. The arid region of Xihaigu, which covers large parts of the province, suffers from severe water shortage, which the canals were intended to alleviate.

Ningxia was the core area of the Western Xia in the 11th–13th centuries, established by the Tangut people; its name, "Peaceful Xia", derived from the Mongol conquest of the state. The Tanguts made significant achievements in literature, art, music, and architecture, particularly invented Tangut script. Long one of the country's poorest areas, a small winemaking industry has become economically important since the 1980s. Before the arrival of viticulture, Ningxia's 6.8 million people, 36 per cent of whom are Muslims from the Hui ethnic group, relied largely on animal grazing, subsistence agriculture and the cultivation of wolfberries used in traditional Chinese medicine. Since then, winemaking has become the premier specialty of Ningxia, and the province devotes almost 40,000 hectares to vineyards and producing 120 million bottles of wine in 2017 – a quarter of the entire nation's production.

History
As a frontier zone between nomadic pastoralists and sedentary farmers, Ningxia was a frequent seat of war and incursions by non-Chinese tribes. Ningxia and its surrounding areas were incorporated into the Qin as the Beidi Commandery as early as the 3rd century BC. To pacify the region, the imperial government established military colonies to reclaim land. In addition, horse pasturages were founded under the Imperial Stud to safeguard the supply of army horses, as early as the Western Han dynasty (206 BC – AD 9). Throughout the Han dynasty and the Tang dynasty there were several large cities established in the region. The Liang Province rebellion at the end of the Han Dynasty affected Ningxia.

By the 11th century the Tangut people had established the Western Xia dynasty on the outskirts of the then-Song dynasty. Jews also lived in Ningxia, as evidenced by the fact that in 1489, after a major flood destroyed Torah scrolls in Kaifeng, a replacement set was sent to the Kaifeng Jews by the Ningbo and Ningxia Jewish communities.

It then came under Mongol domination after Genghis Khan conquered Yinchuan in the early 13th century. Muslims from Central Asia also began moving into Ningxia from the west. By the late 17th century, Ningxia had become a weaving centre, producing many early Chinese carpets. The Muslim Dungan Revolt of the 19th century affected Ningxia.

In 1914, Ningxia was merged with the province of Gansu. In 1928, it became a separate province. Between 1914 and 1928, the Ma clique ruled the provinces of Qinghai, Ningxia and Gansu; General Ma Hongkui was the military governor of Ningxia and had absolute authority in the province. The Muslim conflict in Gansu, which lasted from 1927 to 1930, spilt over into Ningxia. In 1934, warlord and National Revolutionary Army general Sun Dianying attempted to conquer the province, but was defeated by an alliance led by the Ma clique.

From 1950 to 1958, a Kuomintang Islamic insurgency resulted in fighting throughout Northwest China, including Ningxia. In 1954, the Chinese government merged Ningxia with Gansu, but in 1958 Ningxia formally became an autonomous region of China. In 1969, Ningxia received a part of the Inner Mongolian Autonomous Region, but this area was returned in 1979.

A number of Chinese artifacts dating from the Tang dynasty and Song dynasty, some of which had been owned by Emperor Zhenzong, were excavated and then came into the hands of Ma Hongkui, who refused to publicize the findings. Among the artifacts were a white marble tablet from the Tang dynasty, gold nails, and bands made out of metal. It was not until after Ma died that his wife went to Taiwan in 1971 from America to bring the artifacts to Chiang Kai-shek, who turned them over to the Taipei National Palace Museum.

Geography
Present-day Ningxia is one of the nation's smallest provincial-level units and borders the provinces of Shaanxi and Gansu and the Inner Mongolia Autonomous Region. At 3556 meters above sea level, Aobaogeda (敖包疙瘩) in the Helan Mountains is the highest point in Ningxia.

Ningxia is a relatively dry, desert-like region and features a diverse geography of forested mountains and hills, table lands, deserts, flood plains and basins cut through by the Yellow River. The Ningxia ecosystem is one of the least studied regions in the world. Significant irrigation supports the growing of wolfberries, a commonly consumed fruit throughout the region. Ningxia's deserts include the Tengger desert in Shapotou.

The northern section, through which the Yellow River flows, supports the best agricultural land. A railroad, linking Lanzhou with Baotou, crosses the region. A highway has been built across the Yellow River at Yinchuan.

On 16 December 1920, the Haiyuan earthquake, 8.6 magnitude, at 36.6°N, 105.32°W, initiated a series of landslides that killed an estimated 200,000 people. Over 600 large loess landslides created more than 40 new lakes.

In 2006, satellite images indicated that a 700 by 200-meter fenced area within Ningxia—5 km southwest of Yinchuan, near the remote village of Huangyangtan—is a near-exact 1:500 scale terrain model reproduction of a 450 by 350-kilometer area of Aksai Chin bordering India, complete with mountains, valleys, lakes and hills. Its purpose is as yet unknown.

Grasslands
It was reported that approximately 34 percent (33.85 million mu; $km2$) of the region's total surface consisted of grassland. This figure is down from approximately 40 percent in the 1990s. The grasslands are spread over the dry desert-steppe area in the northeast (which forms a part of the Inner Mongolian steppe region), and the hilly pastures located on the semi-arid Loess Plateau in the south. It is ascertained that the grasslands of Ningxia have been degraded to various degrees. Scientists debate the extent to which this degradation occurs over space and time. Historical research has also found limited evidence of expanding grassland degradation and desertification in Ningxia. A major component of land management in Ningxia is a ban on open grazing, which has been in place since 2003. The ecological and socio-economic effects of this Grazing Ban in relation to the grasslands and pastoralists' livelihood are contested. The ban stipulates that animal husbandry be limited to enclosed pens and no open grazing be permitted in certain time periods set by the Autonomous Region's People's Government.

Climate
The region is 1,200 km from the sea and has an arid continental climate on the north to humid continental climate to the south, with average summer temperatures rising to 17 to 24 °C in July and average winter temperatures dropping to between −7 and −15 °C in January. Seasonal extreme temperatures can reach 39 °C in summer and -30 °C in winter. The diurnal temperature variation can reach above 17 °C-change, especially in spring. Annual rainfall averages from 190 to 700 mm, with more rain falling in the south of the region.

Mineral resources
Ningxia is rich in mineral resources with proven deposits of 34 kinds of minerals, much of which located in grassland areas. In 2011 it was estimated that the potential value per capita of these resources accounted for 163.5 percent of the nation's average. Ningxia boasts verified coal reserves of over 30 billion tons, with an estimated reserve of more than 202 billion tons, ranking sixth nationwide. Coal deposits are spread over one-third of the total surface of Ningxia, and mined in four major fields in the Helan and Xiangshan mountains, Ningdong and Yuanzhou (or Guyuan). The region's reserves of oil and natural gas can be found in Yanchi and Lingwu County, and are ideal for large-scale development of oil, natural gas and chemical industries. Ningxia leads China in gypsum deposits, with a proven reserve of more than 4.5 billion tons, of which the rarely found, top-grade gypsum accounts for half of the total deposits. The Hejiakouzi deposit in Tongxin County features a reserve of 20 million tons of gypsum with a total thickness of 100 meters. There is a considerable deposit of quartz sandstone, of which 17 million tons have been ascertained. In addition, there are phosphorus, flint, copper, iron, barite, other minerals and Helan stone – a special clay stone.

Governance
The politics of Ningxia is structured in a dual party-government system like all other governing institutions in mainland China.

The Chairman of the Autonomous Region is the highest-ranking official in the People's Government of Ningxia. In its dual-party government system, the chairman has less power than the Chinese Communist Party (CCP) Ningxia Committee Secretary, colloquially termed the "Ningxia CCP Party Chief".

Ningxia has a friendship agreement with Sogn og Fjordane county of Norway.

Administrative divisions
Ningxia is divided into five prefecture-level divisions: all prefecture-level cities:

The five prefecture-level cities of Ningxia are subdivided into 22 county-level divisions (9 districts, 2 county-level cities, and 11 counties).

Economy
Rural Ningxia was for long an officially designated poverty area, and remains on the lower rungs of the developmental ladder. It is the province with the third smallest GDP (Tibet being the last) in China, even though its neighbors, Inner Mongolia and Shaanxi, are among the strongest emerging provincial economies in the country. Its nominal GDP in 2011 was just 200.0 billion yuan (US$32.7 billion) and a per capita GDP of 21,470 yuan (US$3,143). It comprises 0.44% of the national economy.

Agriculture
Similar to other areas, Ningxia has seen a gradual decline of its peasant population due to rural–urban migration. Despite this, the great majority (62.8 percent) was still agricultural at the time of the survey. Animal husbandry is important for the regional economy. In the main pastoral county, Yanchi, it is even the leading industry when specified for the primary sector. The dominant grazing animals are sheep and goat. In the (semi-)pastoral regions, herders engage in a mixed sedentary farming operation of dryland agriculture and extensive animal husbandry, while full nomadic pastoralism is no longer practiced.

Ningxia is the principal region of China where wolfberries are grown. Other specialties of Ningxia are licorice, products made from Helan stone, fiddlehead and products made from sheepskin.

Ningxia wines are a promising area of development. The Chinese authorities have given approval to the development of the eastern base of the Helan Mountains as an area suitable for wine production. Several large Chinese wine companies including Changyu and Dynasty Wine have begun development in the western region of the province. Together they now own 20,000 acres of land for wine plantations and Dynasty has ploughed 100 million yuan into Ningxia. In addition, the major oil company China Petroleum and Chemical Corporation has founded a grape plantation near the Helan Mountains. The household appliance company Midea has also begun participating in Ningxia's wine industry. Vineyards have been set up in the region.

Industries and economic zones
Yinchuan Economic and Technological Development Zone was established in 1992. Spanning 32 km2, it has an annual economic output Rmb23.7 billion (25.1% up) (US$3.5 billion). Major investors are mainly local enterprises such as Kocel Steel Foundry, FAG Railway Bearing (Ningxia), Ningxia Little Giant Machine Tools, etc. Major industries include machinery and equipment manufacturing, new materials, fine chemicals and the animation industry.

Desheng Industrial Park (in Helan County) is a base for about 400 enterprises. The industrial park has industrial chains from Muslim food and commodities to trade and logistics, new materials and bio-pharmaceuticals that has 80 billion yuan in fixed assets. Desheng is looking to be the most promising industrial park in the city. It achieved a total output value of 4.85 billion in 2008, up 40 percent year-on-year. The local government plans to cut taxes and other fees to reduce the burden on local enterprises. The industrial output value reached 2.68 billion yuan in 2008, an increase of 48 percent from a year earlier.

Airports

 * Yinchuan Hedong International Airport
 * Zhongwei Shapotou Airport
 * Guyuan Liupanshan Airport
 * Wuhai Airport (serves the northern area)

Highways

 * China National Highway 109
 * China National Highway 110
 * China National Highway 211
 * China National Highway 307
 * China National Highway 309
 * China National Highway 312

Bridge

 * Taole Yellow River Expressway Bridge (陶乐黄河大桥)

Rail

 * Baotou–Lanzhou railway
 * Baoji–Zhongwei railway (宝中铁路)

Religion
Islam is the single biggest religious tradition in Ningxia, adhered to by 34% of the population according to a 2010 survey. Many of the Han Chinese practise Chinese folk religions, Taoism, Confucianism and Chinese Buddhism. Christianity was the religion of 1.17% of the province's population according to the Chinese General Social Survey of 2004.

In 2008, there were 3,760 mosques in Ningxia, which is about one per 1730 residents.

Hospitals

 * People's Hospital of Ningxia
 * Hospital of Traditional Chinese Medicine of Ningxia
 * Ningxia Medical College Affiliated Hospital
 * Yinchuan Hospital of Traditional Chinese Medicine
 * Yinchuan People's Hospital
 * Yinchuan Stomatological Hospital
 * Yinchuan Women and Children's Healthcare Center
 * Women and Children's Healthcare Center of Ningixa
 * Yinchuan No.1 People's Hospital
 * Yinchuan No.2 People's Hospital
 * Yinchuan No.3 People's Hospital
 * Shizuishan No.2 People's Hospital
 * Guyuan Hospital of Ningxia

Tourism
One of Ningxia's main tourist spots is the internationally renowned Xixia Tombs site located 30 km west of Yinchuan. The remnants of nine Western Xia emperors' tombs and two hundred other tombs lie within a 50 km² area. Other famous sites in Ningxia include the Helan Mountains, the mysterious 108 stupas, the twin pagodas of Baisikou and the desert research outpost at Shapatou. A less visited tourist spot in Ningxia is the Mount Sumeru Grottoes (须弥山), which is among the ten most famous grottoes in China.

Museums

 * Ningxia Museum, opened in 1988
 * Ningxia Transportation Museum, opened in August 2008
 * Museum of Contemporary Art Yinchuan (MOCA Yinchuan), opened on 8 August 2015.

Notable people

 * Emma Gao, winemaker
 * Zhang Jin, physical chemist and nanotechnologist

title: Ningxia


text:
Talk:Gravity Research Foundation

Chairs

 * Sometimes, attendees sat in chairs with their heads higher than their feet

Really?! That's an awfully strange way to sit. But I guess sitting that would prevent the blood from rushing to your head. Hmmm... maybe the idea has merit.

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Embarrassingly, that's the second time I've made that stupid mistake. I lifted this material from an article I wrote about the Foundation years ago, in which I did the same bone-footed - er, bone-headed thing.

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Seems to me this should be the anti-water foundation, considering that's what actually killed his sister. Or perhaps it could be more positive, the pro-air foundation.
 * Gravity did all the dirty work. Water just took the credit. 209.214.230.142 16:20, 23 June 2006 (UTC)
 * It's curious that Babson placed blame squarely on Gravity. Gravity plays an integral role in generating buoyant forces, which induce a boat to rest on the surface of a body of water. A more productive entity would be the Flotation Device Research Foundation. Or, perhaps he might have just made a donation to the YMCA, because they teach kids how to swim.   — Preceding unsigned comment added by 24.223.130.32 (talk) 21:39, 13 March 2018 (UTC)

Remnants
In my physics textbook (University Physics by Ronald Lane Reese), there is a photo on page 183 of a stone slab with the text: "This monument has been erected by the Gravity Research Foundation. Roger W. Babson, Founder.  It is to remind students of the blessings forthcoming when a semi-insulator is discovered in order to harness gravity as a free power and reduce airplane accidents." And then the year, 1960. The caption says: "A monument on the campus of Middlebury College, Middlebury, Vermont. A similar monument exists at Colby College, Waterville, Maine." This information should be incorporated into the article, but I don't know what other remnants of the foundation exist. --LostLeviathan 14:41, 19 Oct 2004 (UTC)

 * Good point - I had forgotten about those other monuments. I'll add a mention; if more are found, they can be added. - DavidWBrooks 14:49, 19 Oct 2004 (UTC)

Band
In the late 90's in Keene, there was a band named the Gravity Research Foundation, probably named after the stone slab on the corner of Wilson and Winchester Street. Only hearsay on the band though, so not worthy of adding to the article itself. I must have walked past that slab a thousand times...Karmafist 20:51, 2 August 2005 (UTC)

 * There's a GRF stone in Keene? Really? I'll have to remember to check that out. - DavidWBrooks 22:15, 2 August 2005 (UTC)

Hobart
According to the Hobart College "H Book", http://www.hws.edu/pdf/HBook.pdf (page 18), they also have a gravity monument. There's a photograph, too.

Babson College itself
This article on the Babson Globe in Roadside America says:

While you're visiting, look for several odd monuments in the vicinity. A sample:

"This monument has been erected by the Gravity Research Foundation. It is to remind students of the blessings forthcoming when a semi-insulator is discovered in order to harness gravity as a free power and reduce airplane accidents."

Several odd monuments? Dpbsmith (talk) 19:44, 11 December 2005 (UTC)

Gravity monuments
I emailed George Rideout, Jr. President GRF, who responded with the following list of monuments:

Gravity Research Foundation 1960’s Monuments

Bethune-Cookman College – Daytona Beach, FL

Colby College -Waterville, ME

Eastern Baptist College – St. Davids, PA

Eastern Nazarene College – Wallaston, MA

Emory University – Atlanta, GA

Gordon College – Wenham, MA

Hobart & William Mary College – NY

Keane State College – Keane, NH

Middlebury College – Middlebury, VT

Tufts University – Medford, MA

Tuskegee Institute – Tuskegee, AL

University of Tampa – Tampa, FL

Wheaton College – Wheaton, IL

Dpbsmith (talk) 16:49, 12 December 2005 (UTC)

 * Excellent research! - DavidWBrooks 17:00, 12 December 2005 (UTC)

 * My, you do set the bar low! But thanks. P. S. I'm taking the liberty of correcting what looks like obvious misprints/typos in his list. The list above is as he sent it to me. Dpbsmith (talk) 17:37, 12 December 2005 (UTC)

 * In the "citizen journalism / information" world, ANY research beyond checking the second page of the Google search is excellent research. - DavidWBrooks 18:06, 12 December 2005 (UTC)

History
What is a Rauscher and why did it indicate? BillyPreset (talk) 20:24, 21 February 2012 (UTC)

List of award winners
I feel that this list contravenes our rules and guidelines on the use of external links, as it basically is a huge linkfarm. Do we really need to list all 5 awards each year? Do we really need this list at all? Note that not even this foundation themselves have such a list on their website, but split it up according to year or alphabetical order. I think a simple link to their awards page would be sufficient. Note also that the vast majority of the awardees are not notable (nor is this award enough to meet WP:ACADEMIC, I think). The article in general needs some work. The lead, for example, speaks of the foundation in the past, yet these awards are still handed out annually and there is an active website. --Randykitty (talk) 10:39, 27 December 2014 (UTC)
 * OK, I'd generally agree; like many lists that get added to articles by a sort of completionism urge, it is largely unnecessary. I missed the past tense in the lede. - DavidWBrooks (talk) 13:48, 27 December 2014 (UTC)

Prize Amount
This page claims that the prize amount is $4000.00 but the anti-gravity article claims the prize is $5000.00. Can anyone confirm which is right?Teknozilla (talk) 09:13, 18 July 2017 (UTC)Teknozilla
 * The official page says $4,000 - what "anti-gravity article" do you mean? - DavidWBrooks (talk) 10:38, 18 July 2017 (UTC)
 * Ah, I found the other article and fixed the amount. - DavidWBrooks (talk) 10:41, 18 July 2017 (UTC)

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title: Talk:Gravity Research Foundation


text:
Paul Gerhardt

Paul Gerhardt (12 March 1607 – 27 May 1676) was a German theologian, Lutheran minister and hymnodist.

Biography
Gerhardt was born into a middle-class family at Gräfenhainichen, a small town between Halle and Wittenberg. His father died in 1619, his mother in 1621. At the age of fifteen, he entered the Fürstenschule in Grimma. The school was known for its pious atmosphere and stern discipline. The school almost closed in 1626 when the plague came to Grimma, but Paul remained and graduated from there in 1627. In January 1628 he enrolled in the University of Wittenberg. There, two teachers in particular had an influence on him: Paul Röber and Jacob Martini. Both of these men were staunch Lutherans, promoting its teachings not only in the classroom but in sermons and hymns. Röber in particular often took his sermon texts from hymns. In this way Gerhardt was taught the use of hymnody as a tool of pastoral care and instruction. Gerhardt graduated from the University of Wittenberg around 1642. Due to the troubles of the Thirty Years War it seems he was not immediately placed as a pastor, and thus moved to Berlin where he worked as tutor in the family of an advocate named Andreas Barthold. During his time in Berlin his hymns and poems brought him to the attention of Johann Crüger, the cantor and organist at the Nicolaikirche in Berlin. Crüger was impressed by Gerhardt's hymns and included many of them in his Praxis pietatis melica. The hymns proved popular, and Gerhardt and Crüger began a collaboration and friendship that continued for many years.

In September 1651, Gerhardt received his first ecclesiastical appointment as the new Probst at Mittenwalde (a small town near Berlin). It was during his time in Mittenwalde when he composed most of his hymns. Also while there he married Anna Maria Barthold, one of the daughters of Andreas Barthold. Their first child was born there in 1656, but died in infancy; a memorial tablet in the church shows their grief.

While Gerhardt was a devoted pastor in Mittenwalde it appears he missed Berlin. In 1657 he was called to be a Deacon (Associate Pastor) to the Nikolaikirche of Berlin. He seems to have had some hesitancy about leaving Mittenwalde since it was only after long deliberation that he accepted the appointment.

When Gerhardt came to Berlin he found a city full of strife between the Lutheran and Reformed clergy. The Elector at the time was Friedrich Wilhelm I of Brandenburg, who was Reformed. He wanted to make peace between the clerical factions, but being Reformed himself, he concentrated most of his efforts on making his lands more Calvinist. He placed only Reformed pastors into parishes, removed the Lutheran professors from the University of Frankfurt and forbade students from his lands to study at the University of Wittenberg.

He also sponsored a series of conferences between the Lutheran and Reformed clergy in the hopes of having them arrive at some consensus, but the result was the opposite: the more the two sides argued, the further apart they found themselves. Gerhardt was a leading voice among the Lutheran clergy, and drew up many of the statements in defense of the Lutheran faith. At the same time he was renowned for acting fraternally not only with the Lutherans but also with the Reformed clergy; he was respected and very well liked by all. His sermons and devotional writings were so free from controversy that many among the Reformed attended his services, and the wife of the Elector, Louisa Henrietta, was a great admirer of him and his hymns.

The Elector, however, was growing impatient with a lack of success at his conferences. He put an end to them in 1664 and published his "syncretistic" edict. Since the edict disallowed the Formula of Concord, one of the Lutheran Confessions as contained in the Book of Concord, many Lutheran clergy could not bring themselves to comply with the edict. Gerhardt was thus removed from his position in 1666.

The citizens of Berlin petitioned to have him restored, and owing to their repeated requests an exception to the edict was made for Gerhardt, although his conscience did not allow him to retain a post which, appeared to him, could only be held on condition of a tacit repudiation of the Formula of Concord. For over a year he lived in Berlin without fixed employment. During this time his wife also died, leaving him with only one surviving child. Ironically the edict was withdrawn a few months later, although by this time his patroness, Electress Louisa Henrietta had died as well and so he was still without a position. In October 1668 he was called as archdeacon of Lübben in the duchy of Saxe-Merseburg, where, after a ministry of eight years, he died on 27 May 1676.

Gerhardt is considered Germany's greatest hymn writer. Many of his best-known hymns were originally published in various church hymn-books, as for example in that for Brandenburg, which appeared in 1658; others first saw the light in Johann Crüger's Geistliche Kirchenmelodien (1647) and Praxis pietatis melica. The first complete collection is the Geistliche Andachten, published in 1666–1667 by Ebeling, music director in Berlin. No hymn by Gerhardt of a later date than 1667 is known to exist.

The life of Gerhardt has been written by Roth (1829), by Langbecker (1841), by Schultz (1842), by Wildenhahn (1845) and by Bachmann (1863); also by Kraft in Ersch's und Gruber's ''Allg. Encyc'' (1855). A short biography was also done by William Dallmann, reprinted in 2003. The best modern edition of the hymns, published by Wackernagel in 1843, has often been reprinted. There is an English translation by Kelly (Paul Gerhardt's Spiritual Songs, 1867).

Commemoration
Paul Gerhardt is commemorated on 26 October in the Calendar of Saints used by some Lutheran churches in the United States, on which day the achievements of Philipp Nicolai and Johann Heermann are also commemorated.

A plaque in Wittenberg marks his lodgings, close to the university.

Hymns
Johann Sebastian Bach used several single stanzas of Gerhardt's hymns in his church cantatas, motets, Passions and Christmas Oratorio. The hymn "Ich hab in Gottes Herz und Sinn" is the base for Bach's chorale cantata BWV 92.

Hymn texts by Gerhardt, listed with a translation of the first line, associated hymn tune, base, liturgical occasion, the number in the current German Protestant hymnal Evangelisches Gesangbuch (EG) and the Catholic Gotteslob (GL), use in Bachs works (BWV numbers between 1 and 200 are cantatas, BWV 245 is the St John Passion, BWV 244 is the St Matthew Passion, BWV 248 the Christmas Oratorio, BWV 439–507 appear in Schemellis Gesangbuch), and/or notes:

title: Paul Gerhardt


text:
Hamam (film)

Hamam (Il bagno turco, also known as Steam: The Turkish Bath) is a 1997 Italian-Turkish-Spanish film directed by Ferzan Özpetek about the powerful transformations certain places can cause in people.

Synopsis
Francesco (Alessandro Gassman) and Marta (Francesca d'Aloja) are an uptight Italian couple running a small design firm. Their marriage, once the most important thing to both, has lost all meaning. Francesco loses interest in Marta, prompting her to start an affair with Paolo, their business partner.

Francesco's aunt Anita, the black sheep of the family, dies in Istanbul, where Francesco goes to try to sell the property he has inherited as quickly as possible.

The family who had managed the property under Anita's supervision and direction welcomes him with hospitality, but they are concerned about what the future holds for them. Their young son Mehmet (Mehmet Günsür) is particularly eager to show their handsome guest around.

When Francesco discovers the property includes a derelict hamam, a Turkish bath, he instead decides to restore the hamam and reopen it to the public. During the restoration, he starts a relationship with Mehmet.

Meanwhile, Marta arrives in Istanbul to get a speedy divorce from Francesco, but she is taken aback when she realizes how much Francesco has changed from his old self: both the hamam and Mehmet's unconditional affection were just what he needed, giving him back a purpose in life. Marta falls in love with him again, causing Rome and the divorce to lose importance for her.

Francesco's unwillingness to sell the property makes him enemies, some of whom ultimately murder him.

Marta decides to stay in Istanbul and run the hamam, the final scene suggesting she has turned into a second Anita.

Cast

 * Alessandro Gassman as Francesco
 * Francesca d'Aloja as Marta
 * Carlo Cecchi as Oscar
 * Halil Ergün as Osman
 * Serif Sezer as Perran
 * Mehmet Günsür as Mehmet
 * Basak Köklükaya as Fusun
 * Alberto Molinari as Paolo
 * Zozo Toledo as Zozo
 * Ludovica Modugno as Voice of Aunt Anita (voice)

Other cast members; Zerrin Arbas, Necdet Mahfi Ayral, Murat Ilker and Alper Kul

title: Hamam (film)


text:
Proopiomelanocortin

Pro-opiomelanocortin (POMC) is a precursor polypeptide with 241 amino acid residues. POMC is synthesized in corticotrophs of the anterior pituitary from the 267-amino-acid-long polypeptide precursor pre-pro-opiomelanocortin (pre-POMC), by the removal of a 26-amino-acid-long signal peptide sequence during translation. POMC is part of the central melanocortin system.

Function
POMC is cut (cleaved) to give rise to multiple peptide hormones. Each of these peptides is packaged in large dense-core vesicles that are released from the cells by exocytosis in response to appropriate stimulation:
 * α-MSH produced by neurons in the ventromedial nucleus has important roles in the regulation of appetite (POMC neuron stimulation results in satiety. ) and sexual behavior, while α-MSH secreted from the intermediate lobe of the pituitary regulates the movement of melanin produced from melanocytes in skin.
 * ACTH is a peptide hormone that regulates the secretion of mainly glucocorticoids from the cells of the zona fasciculata of the adrenal cortex. ACTH can also regulate secretion of gonadocorticoids from the cells of the zona reticularis since they also express ACTH receptors.
 * β-Endorphin and [Met]enkephalin are endogenous opioid peptides with widespread actions in the brain.

Synthesis
The POMC gene is located on chromosome 2p23.3. The POMC gene is expressed in both the anterior and intermediate lobes of the pituitary gland. This gene encodes a 285-amino acid polypeptide hormone precursor that undergoes extensive, tissue-specific, post-translational processing via cleavage by subtilisin-like enzymes known as prohormone convertases. The encoded protein is synthesized mainly in corticotroph cells of the anterior pituitary, where four cleavage sites are used; adrenocorticotrophin (ACTH), essential for normal steroidogenesis and the maintenance of normal adrenal weight, and β-lipotropin are the major end-products. However, there are at least eight potential cleavage sites within the polypeptide precursor and, depending on tissue type and the available convertases, processing may yield as many as ten biologically active peptides involved in diverse cellular functions. Cleavage sites consist of the sequences Arg-Lys, Lys-Arg, or Lys-Lys. Enzymes responsible for processing of POMC peptides include prohormone convertase 1 (PC1), prohormone convertase 2 (PC2), carboxypeptidase E (CPE), peptidyl α-amidating monooxygenase (PAM), N-acetyltransferase (N-AT), and prolylcarboxypeptidase (PRCP).

The processing of POMC involves glycosylations, acetylations, and extensive proteolytic cleavage at sites shown to contain regions of basic protein sequences. However, the proteases that recognize these cleavage sites are tissue-specific. In some tissues, including the hypothalamus, placenta, and epithelium, all cleavage sites may be used, giving rise to peptides with roles in pain and energy homeostasis, melanocyte stimulation, and immune modulation. These include several distinct melanotropins, lipotropins, and endorphins that are contained within the adrenocorticotrophin and β-lipotropin peptides.

It is synthesized by:
 * Corticotrope cells of the anterior pituitary gland
 * Melanotrope cells of the intermediate lobe of the pituitary gland
 * Neurons in the arcuate nucleus of the hypothalamus
 * Smaller populations of neurons in the dorsomedial hypothalamus and brainstem
 * Melanocytes in the skin

Regulation by the photoperiod
The levels of proopiomelanocortin (pomc) are regulated indirectly in some animals by the photoperiod. It is referred to the hours of light during a day and it changes across the seasons. Its regulation depends on the pathway of thyroid hormones that is regulated directly by the photoperiod. An example are the siberian hamsters who experience physiological seasonal changes dependent on the photoperiod. During spring in this species, when there is more than 13 hours of light per day, iodothyronine deiodinase 2 (DIO2) promotes the conversion of the prohormone thyroxine (T4) to the active hormone triiodothyronine (T3) through the removal of an iodine atom on the outer ring. It allows T3 to bind to the thyroid hormone receptor (TR), which then binds to thyroid hormone response elements (TREs) in the DNA sequence. The pomc proximal promoter sequence contains two thyroid-receptor 1b (Thrb) half-sites: TCC-TGG-TGA and TCA-CCT-GGA indicating that T3 may be capable of directly regulating pomc transcription. For this reason during spring and early summer, the level of pomc increases due to the increased level of T3.

However, during autumn and winter, when there is less than 13 hours of light per day, iodothyronine desiodinase 3 removes an iodine atom which converts thyroxine to the inactive reverse triiodothyronine (rT3), or which converts the active triiodothyronine to diiodothyronine (T2). Consequently, there is less T3 and it blocks the transcription of pomc, which reduces its levels during these seasons.

Influences of photoperiods on relevant similar biological endocrine changes that demonstrate modifications of thyroid hormone regulation in humans have yet to be adequately documented.

Derivatives
The large molecule of POMC is the source of several important biologically active substances. POMC can be cleaved enzymatically into the following peptides:
 * N-Terminal Peptide of Proopiomelanocortin (NPP, or pro-γ-MSH)
 * α-Melanotropin (α-Melanocyte-Stimulating Hormone, or α-MSH)
 * β-Melanotropin (β-MSH)
 * γ-Melanotropin (γ-MSH)
 * 𝛿-Melanocyte-Stimulating Hormone (𝛿-MSH, present in sharks )
 * ε-Melanocyte-Stimulating Hormone (ε-MSH, present in some teleosts )
 * Corticotropin (Adrenocorticotropic Hormone, or ACTH)
 * Corticotropin-like Intermediate Peptide (CLIP)
 * β-Lipotropin (β-LPH)
 * Gamma Lipotropin (γ-LPH)
 * β-Endorphin
 * [Met]Enkephalin

Although the N-terminal 5 amino acids of β-endorphin are identical to the sequence of [Met]enkephalin, it is not generally thought that β-endorphin is converted into [Met]enkephalin. Instead, [Met]enkephalin is produced from its own precursor, proenkephalin A.

The production of β-MSH occurs in humans but not in mice or rats due to the absence of the enzymatic processing site in the rodent POMC.

Clinical significance
Mutations in this gene have been associated with early onset obesity, adrenal insufficiency, and red hair pigmentation.

A study concluded that a polymorphism was associated with higher fasting insulin levels in the obese patients only. These findings support the hypothesis that the melanocortin pathway may modulate glucose metabolism in obese subjects indicating a possible gene-environment interaction. POMC variant may be involved in the natural history of polygenic obesity, contributing to the link between type 2 diabetes and obesity.

Septic patients have increased circulating plasma concentrations of POMC. The clinical significance is currently under investigation. Further augmenting systemic glucocorticoid availability via infusion of hydrocortisone in septic mice resulted in a suppression of ACTH, an endproduct of POMC, but not in a suppression of POMC.

Dogs
A deletion mutation common in Labrador Retriever and Flat-Coated Retriever dogs is associated with increased interest in food and subsequent obesity.

Drug target
POMC is used as a target for a medication used to treat obesity in humans. The combination of bupropion and naltrexone acts via hypothalamic POMC neurons to decrease appetite.

Two humans with POMC deficiency have been treated with setmelanotide, a melanocortin-4 receptor agonist.

Interactions
Proopiomelanocortin has been shown to interact with melanocortin 4 receptor. The endogenous agonists of melanocortin 4 receptor include α-MSH, β-MSH, γ-MSH, and ACTH. The fact that these are all cleavage products of POMC should suggest likely mechanisms of this interaction.

title: Proopiomelanocortin