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Positive
Plowing:
Loosens and aerates the top layer of soil or horizon A, which facilitates planting the crop.
Helps mix harvest residue, organic matter (humus), and nutrients evenly into the soil.
Mechanically destroys weeds.
Dries the soil before seeding (in wetter climates, tillage aids in keeping the soil drier).
When done in autumn, helps exposed soil crumble over winter through frosting and defrosting, which helps prepare a smooth surface for spring planting.
Can reduce infestations of slugs, cut worms, army worms, and harmful insects as they are attracted by leftover residues from former crops.
Reduces the risk of crop diseases which can be harbored in surface residues.
Negative
Dries the soil before seeding.
Soil loses nutrients, like nitrogen and fertilizer, and its ability to store water.
Decreases the water infiltration rate of soil. (Results in more runoff and erosion as the soil absorbs water more slowly than before)
Tilling the soil results in dislodging the cohesiveness of the soil particles, thereby inducing erosion.
Chemical runoff.
Reduces organic matter in the soil.
Reduces microbes, earthworms, ants, etc.
Destroys soil aggregates.
Compaction of the soil, also known as a tillage pan.
Eutrophication (nutrient runoff into a body of water).
Archaeology
Tilling can damage ancient structures such as long barrows. In the UK, half of the long barrows in Gloucestershire and almost all the burial mounds in Essex have been damaged. According to English Heritage in 2003, ploughing with modern powerful tractors had done as much damage in the last six decades as traditional farming did in the previous six centuries. | Tillage | Wikipedia | 349 | 46191 | https://en.wikipedia.org/wiki/Tillage | Technology | Horticultural techniques | null |
General comments
The type of implement makes the most difference, although other factors can have an effect.
Tilling in absolute darkness (night tillage) might reduce the number of weeds that sprout following the tilling operation by half. Light is necessary to break the dormancy of some weed species' seed, so if fewer seeds are exposed to light during the tilling process, fewer will sprout. This may help reduce the amount of herbicides needed for weed control.
Greater speeds, when using certain tillage implements (disks and chisel plows), lead to more intensive tillage (i.e., less residue is on the soil surface).
Increasing the angle of disks causes residues to be buried more deeply. Increasing their concavity makes them more aggressive.
Chisel plows can have spikes or sweeps. Spikes are more aggressive.
Percentage residue is used to compare tillage systems because the amount of crop residue affects the soil loss due to erosion.
Alternatives
Modern agricultural science has greatly reduced the use of tillage. Crops can be grown for several years without any tillage through the use of herbicides to control weeds, crop varieties that tolerate packed soil, and equipment that can plant seeds or fumigate the soil without really digging it up. This practice, called no-till farming, reduces costs and environmental change by reducing soil erosion and diesel fuel usage.
Site preparation of forest land
Site preparation is any of the various treatments applied to a site to ready it for seeding or planting. The purpose is to facilitate the regeneration of that site by the chosen method. Site preparation may be designed to achieve, singly or in any combination, improved access by reducing or rearranging slash and ameliorating adverse forest floor, soil, vegetation, or other biotic factors. Site preparation is undertaken to ameliorate one or more constraints that would otherwise be likely to thwart management objectives. A valuable bibliography on the effects of soil temperature and site preparation on subalpine and boreal tree species has been prepared by McKinnon et al. (2002).
Site preparation is the work that is done before a forest area is regenerated. Some types of site preparation are burning.
Burning
Broadcast burning is commonly used to prepare clearcut sites for planting, e.g., in central British Columbia, and in the temperate region of North America generally.
Prescribed burning is carried out primarily for slash hazard reduction and to improve site conditions for regeneration; all or some of the following benefits may accrue: | Tillage | Wikipedia | 510 | 46191 | https://en.wikipedia.org/wiki/Tillage | Technology | Horticultural techniques | null |
a) Reduction of logging slash, plant competition, and humus prior to direct seeding, planting, scarifying or in anticipation of natural seeding in partially cut stands or in connection with seed-tree systems.
b) Reduction or elimination of unwanted forest cover prior to planting or seeding, or prior to preliminary scarification thereto.
c) Reduction of humus on cold, moist sites to favour regeneration.
d) Reduction or elimination of slash, grass, or brush fuels from strategic areas around forested land to reduce the chances of damage by wildfire.
Prescribed burning for preparing sites for direct seeding was tried on a few occasions in Ontario, but none of the burns was hot enough to produce a seedbed that was adequate without supplementary mechanical site preparation.
Changes in soil chemical properties associated with burning include significantly increased pH, which Macadam (1987) in the Sub-boreal Spruce Zone of central British Columbia found persisting more than a year after the burn. Average fuel consumption was 20 to 24 t/ha and the forest floor depth was reduced by 28% to 36%. The increases correlated well with the amounts of slash (both total and ≥7 cm diameter) consumed. The change in pH depends on the severity of the burn and the amount consumed; the increase can be as much as 2 units, a 100-fold change. Deficiencies of copper and iron in the foliage of white spruce on burned clearcuts in central British Columbia might be attributable to elevated pH levels.
Even a broadcast slash fire in a clearcut does not give a uniform burn over the whole area. Tarrant (1954), for instance, found only 4% of a 140-ha slash burn had burned severely, 47% had burned lightly, and 49% was unburned. Burning after windrowing obviously accentuates the subsequent heterogeneity.
Marked increases in exchangeable calcium also correlated with the amount of slash at least 7 cm in diameter consumed. Phosphorus availability also increased, both in the forest floor and in the 0 cm to 15 cm mineral soil layer, and the increase was still evident, albeit somewhat diminished, 21 months after burning. However, in another study in the same Sub-boreal Spruce Zone found that although it increased immediately after the burn, phosphorus availability had dropped to below pre-burn levels within 9 months. | Tillage | Wikipedia | 475 | 46191 | https://en.wikipedia.org/wiki/Tillage | Technology | Horticultural techniques | null |
Nitrogen will be lost from the site by burning, though concentrations in remaining forest floor were found by Macadam (1987) to have increased in two out of six plots, the others showing decreases. Nutrient losses may be outweighed, at least in the short term, by improved soil microclimate through the reduced thickness of forest floor where low soil temperatures are a limiting factor.
The Picea/Abies forests of the Alberta foothills are often characterized by deep accumulations of organic matter on the soil surface and cold soil temperatures, both of which make reforestation difficult and result in a general deterioration in site productivity; Endean and Johnstone (1974) describe experiments to test prescribed burning as a means of seedbed preparation and site amelioration on representative clear-felled Picea/Abies areas. Results showed that, in general, prescribed burning did not reduce organic layers satisfactorily, nor did it increase soil temperature, on the sites tested. Increases in seedling establishment, survival, and growth on the burned sites were probably the result of slight reductions in the depth of the organic layer, minor increases in soil temperature, and marked improvements in the efficiency of the planting crews. Results also suggested that the process of site deterioration has not been reversed by the burning treatments applied.
Ameliorative intervention
Slash weight (the oven-dry weight of the entire crown and that portion of the stem less than four inches in diameter) and size distribution are major factors influencing the forest fire hazard on harvested sites. Forest managers interested in the application of prescribed burning for hazard reduction and silviculture, were shown a method for quantifying the slash load by Kiil (1968). In west-central Alberta, he felled, measured, and weighed 60 white spruce, graphed (a) slash weight per merchantable unit volume against diameter at breast height (dbh), and (b) weight of fine slash (<1.27 cm) also against dbh, and produced a table of slash weight and size distribution on one acre of a hypothetical stand of white spruce. When the diameter distribution of a stand is unknown, an estimate of slash weight and size distribution can be obtained from average stand diameter, number of trees per unit area, and merchantable cubic foot volume. The sample trees in Kiil's study had full symmetrical crowns. Densely growing trees with short and often irregular crowns would probably be overestimated; open-grown trees with long crowns would probably be underestimated. | Tillage | Wikipedia | 506 | 46191 | https://en.wikipedia.org/wiki/Tillage | Technology | Horticultural techniques | null |
The need to provide shade for young outplants of Engelmann spruce in the high Rocky Mountains is emphasized by the U.S. Forest Service. Acceptable planting spots are defined as microsites on the north and east sides of down logs, stumps, or slash, and lying in the shadow cast by such material. Where the objectives of management specify more uniform spacing, or higher densities, than obtainable from an existing distribution of shade-providing material, redistribution or importing of such material has been undertaken.
Access
Site preparation on some sites might be done simply to facilitate access by planters, or to improve access and increase the number or distribution of microsites suitable for planting or seeding.
Wang et al. (2000) determined field performance of white and black spruces 8 and 9 years after outplanting on boreal mixedwood sites following site preparation (Donaren disc trenching versus no trenching) in 2 plantation types (open versus sheltered) in southeastern Manitoba. Donaren trenching slightly reduced the mortality of black spruce but significantly increased the mortality of white spruce. Significant difference in height was found between open and sheltered plantations for black spruce but not for white spruce, and root collar diameter in sheltered plantations was significantly larger than in open plantations for black spruce but not for white spruce. Black spruce open plantation had significantly smaller volume (97 cm3) compared with black spruce sheltered (210 cm3), as well as white spruce open (175 cm3) and sheltered (229 cm3) plantations. White spruce open plantations also had smaller volume than white spruce sheltered plantations. For transplant stock, strip plantations had a significantly higher volume (329 cm3) than open plantations (204 cm3). Wang et al. (2000) recommended that sheltered plantation site preparation should be used.
Mechanical
Up to 1970, no "sophisticated" site preparation equipment had become operational in Ontario, but the need for more efficacious and versatile equipment was increasingly recognized. By this time, improvements were being made to equipment originally developed by field staff, and field testing of equipment from other sources was increasing. | Tillage | Wikipedia | 426 | 46191 | https://en.wikipedia.org/wiki/Tillage | Technology | Horticultural techniques | null |
According to J. Hall (1970), in Ontario at least, the most widely used site preparation technique was post-harvest mechanical scarification by equipment front-mounted on a bulldozer (blade, rake, V-plow, or teeth), or dragged behind a tractor (Imsett or S.F.I. scarifier, or rolling chopper). Drag type units designed and constructed by Ontario's Department of Lands and Forests used anchor chain or tractor pads separately or in combination, or were finned steel drums or barrels of various sizes and used in sets alone or combined with tractor pad or anchor chain units.
J. Hall's (1970) report on the state of site preparation in Ontario noted that blades and rakes were found to be well suited to post-cut scarification in tolerant hardwood stands for natural regeneration of yellow birch. Plows were most effective for treating dense brush prior to planting, often in conjunction with a planting machine. Scarifying teeth, e.g., Young's teeth, were sometimes used to prepare sites for planting, but their most effective use was found to be preparing sites for seeding, particularly in backlog areas carrying light brush and dense herbaceous growth. Rolling choppers found application in treating heavy brush but could be used only on stone-free soils. Finned drums were commonly used on jack pine–spruce cutovers on fresh brushy sites with a deep duff layer and heavy slash, and they needed to be teamed with a tractor pad unit to secure good distribution of the slash. The S.F.I. scarifier, after strengthening, had been "quite successful" for 2 years, promising trials were under way with the cone scarifier and barrel ring scarifier, and development had begun on a new flail scarifier for use on sites with shallow, rocky soils. Recognition of the need to become more effective and efficient in site preparation led the Ontario Department of Lands and Forests to adopt the policy of seeking and obtaining for field testing new equipment from Scandinavia and elsewhere that seemed to hold promise for Ontario conditions, primarily in the north. Thus, testing was begun of the Brackekultivator from Sweden and the Vako-Visko rotary furrower from Finland. | Tillage | Wikipedia | 453 | 46191 | https://en.wikipedia.org/wiki/Tillage | Technology | Horticultural techniques | null |
Mounding
Site preparation treatments that create raised planting spots have commonly improved outplant performance on sites subject to low soil temperature and excess soil moisture. Mounding can certainly have a big influence on soil temperature. Draper et al. (1985), for instance, documented this as well as the effect it had on root growth of outplants (Table 30).
The mounds warmed up quickest, and at soil depths of 0.5 cm and 10 cm averaged 10 and 7 °C higher, respectively, than in the control. On sunny days, daytime surface temperature maxima on the mound and organic mat reached 25 °C to 60 °C, depending on soil wetness and shading. Mounds reached mean soil temperatures of 10 °C at 10 cm depth 5 days after planting, but the control did not reach that temperature until 58 days after planting. During the first growing season, mounds had 3 times as many days with a mean soil temperature greater than 10 °C than did the control microsites.
Draper et al.'s (1985) mounds received 5 times the amount of photosynthetically active radiation (PAR) summed over all sampled microsites throughout the first growing season; the control treatment consistently received about 14% of daily background PAR, while mounds received over 70%. By November, fall frosts had reduced shading, eliminating the differential. Quite apart from its effect on temperature, incident radiation is also important photosynthetically. The average control microsite was exposed to levels of light above the compensation point for only 3 hours, i.e., one-quarter of the daily light period, whereas mounds received light above the compensation point for 11 hours, i.e., 86% of the same daily period. Assuming that incident light in the 100–600 μE/m2/s intensity range is the most important for photosynthesis, the mounds received over 4 times the total daily light energy that reached the control microsites. | Tillage | Wikipedia | 395 | 46191 | https://en.wikipedia.org/wiki/Tillage | Technology | Horticultural techniques | null |
Orientation of linear site preparation
With linear site preparation, orientation is sometimes dictated by topography or other considerations, but the orientation can often be chosen. It can make a difference. A disk-trenching experiment in the Sub-boreal Spruce Zone in interior British Columbia investigated the effect on growth of young outplants (lodgepole pine) in 13 microsite planting positions: berm, hinge, and trench in each of north, south, east, and west aspects, as well as in untreated locations between the furrows. Tenth-year stem volumes of trees on south-, east-, and west-facing microsites were significantly greater than those of trees on north-facing and untreated microsites. However, planting spot selection was seen to be more important overall than trench orientation.
In a Minnesota study, the N–S strips accumulated more snow but snow melted faster than on E–W strips in the first year after felling. Snow-melt was faster on strips near the centre of the strip-felled area than on border strips adjoining the intact stand. The strips, 50 feet (15.24 m) wide, alternating with uncut strips 16 feet (4.88 m) wide, were felled in a Pinus resinosa stand, aged 90 to 100 years. | Tillage | Wikipedia | 268 | 46191 | https://en.wikipedia.org/wiki/Tillage | Technology | Horticultural techniques | null |
A threshing machine or a thresher is a piece of farm equipment that separates grain seed from the stalks and husks. It does so by beating the plant to make the seeds fall out. Before such machines were developed, threshing was done by hand with flails: such hand threshing was very laborious and time-consuming, taking about one-quarter of agricultural labour by the 18th century. Mechanization of this process removed a substantial amount of drudgery from farm labour. The first threshing machine was invented circa 1786 by the Scottish engineer Andrew Meikle, and the subsequent adoption of such machines was one of the earlier examples of the mechanization of agriculture. During the 19th century, threshers and mechanical reapers and reaper-binders gradually became widespread and made grain production much less laborious.
Separate reaper-binders and threshers have largely been replaced by machines that combine all of their functions, that is combine harvesters or combines. However, the simpler machines remain important as appropriate technology in low-capital farming contexts, both in developing countries and in developed countries on small farms that strive for especially high levels of self-sufficiency. For example, pedal-powered threshers are a low-cost option, and some Amish sects use horse-drawn binders and old-style threshers.
As the verb thresh is cognate with the verb thrash (and synonymous in the grain-beating sense), the names thrashing machine and thrasher are (less common) alternate forms.
Early social impacts
The Swing Riots in the UK were partly a result of the threshing machine. Following years of war, high taxes and low wages, farm labourers finally revolted in 1830. They had faced unemployment for years, due to the widespread introduction of the threshing machine and the policy of enclosing fields. No longer were thousands of men needed to tend the crops; a few would suffice. With fewer jobs, lower wages and no prospects, the threshing machine was the final straw; it would place them on the brink of starvation. The Swing Rioters smashed threshing machines and threatened farmers who had them. The riots were dealt with very harshly. Nine of the rioters were hanged and a further 450 were transported to Australia.
Later adoption | Threshing machine | Wikipedia | 476 | 46193 | https://en.wikipedia.org/wiki/Threshing%20machine | Technology | Farm and garden machinery | null |
Early threshing machines were hand-fed and horse-powered. Some were housed in a specially constructed building, a gin gang, which would be attached to a threshing barn. They were small by today's standards and were about the size of an upright piano. Later machines were steam-powered, driven by a portable engine or traction engine. Isaiah Jennings, a skilled inventor, created a small thresher that does not harm the straw in the process. In 1834, John Avery and Hiram Abial Pitts devised significant improvements to a machine that automatically threshes and separates grain from the chaff, freeing farmers from a slow and laborious process. Avery and Pitts were granted United States patent #542 on December 29, 1837.
John Ridley, an Australian inventor, also developed a threshing machine in South Australia in 1843.
The 1881 Household Cyclopedia said of Meikle's machine:
"Since the invention of this machine, Mr. Meikle and others have progressively introduced a variety of improvements, all tending to simplify the labour, and to augment the quantity of the work performed. When first erected, though the grain was equally well separated from the straw, yet as the whole of the straw, chaff, and grain, was indiscriminately thrown into a confused heap, the work could only with propriety be considered as half executed. By the addition of rakes, or shakers, and two pairs of fanners, all driven by the same machinery, the different processes of thrashing, shaking, and winnowing are now all at once performed, and the grain immediately prepared for the public market. When it is added, that the quantity of grain gained from the superior powers of the machine is fully equal to a twentieth part of the crop, and that, in some cases, the expense of thrashing and cleaning the grain is considerably less than what was formerly paid for cleaning it alone, the immense saving arising from the invention will at once be seen." | Threshing machine | Wikipedia | 411 | 46193 | https://en.wikipedia.org/wiki/Threshing%20machine | Technology | Farm and garden machinery | null |
"The expense of horse labour, from the increased value of the animal and the charge of his keeping, being an object of great importance, it is recommended that, upon all sizable farms, that is to say, where two hundred acres [800,000 m²], or upwards, of grain are sown, the machine should be worked by wind, unless where local circumstances afford the conveniency of water. Where coals are plenty and cheap, steam may be advantageously used for working the machine."
Steam-powered machines used belts connected to a traction engine; often both engine and thresher belonged to a contractor who toured the farms of a district. Steam remained a viable commercial option until the early post-WWII years.
Modern developments
In Europe and Americas
Modern-day combines harvesters (or simply combines) operate on the same principles and use the same components as the original threshing machines built in the 19th century. Combines also perform the reaping operation at the same time. The name combine is derived from the fact that the two steps are combined in a single machine. Also, most modern combines are self-powered (usually by a diesel engine) and self-propelled, although tractor-powered, pull-type combines models were offered by John Deere and Case International into the 1990s.
Today, as in the 19th century, threshing begins with a cylinder and concave. The cylinder has sharp serrated bars, and rotates at high speed (about 500 RPM) so that the bars beat against the entire plant as it is mechanically fed from the reaping equipment at the front of the combine to the gap between the concave and the rotating beater/cylinder. The concave is curved to match the curve of the cylinder, and the grain, now separated from the plant stalks falls immediately through grated openings in the concave as it is beaten. The motion of the rotating cylinder thrusts the remaining straw and chaff toward the rear of the machine.
Whilst the majority of the grain falls through the concave, the straw is carried by a set of "walkers" to the rear of the machine, allowing any grain and chaff still in the straw to fall below. Below the straw walkers, a fan blows a stream of air across the grain, removing dust and small bits of crushed plant material out of the back of the combine. The residues fall to the ground and occasionally are collected for other purposes, such as fodder. | Threshing machine | Wikipedia | 499 | 46193 | https://en.wikipedia.org/wiki/Threshing%20machine | Technology | Farm and garden machinery | null |
The grain, either coming through the concave or the walkers, meets a set of sieves mounted on an assembly called a shoe, which is shaken mechanically. The top sieve has larger openings and serves to remove large pieces of chaff from the grain. The lower sieve separates clean grain, which falls through, from incompletely threshed pieces. The incompletely threshed grain is returned to the cylinder by means of a system of conveyors, where the process repeats.
Some threshing machines were equipped with a bagger, which invariably held two bags, one being filled, and the other being replaced with an empty. A worker called a sewer removed and replaced the bags, and sewed full bags shut with a needle and thread. Other threshing machines would discharge grain from a conveyor, for bagging by hand. Combines are equipped with a grain tank, which accumulates grain for deposit in a truck or wagon.
A large amount of chaff and straw would accumulate around a threshing machine, and several innovations, such as the air chaffer, were developed to deal with this. Combines generally chop and disperse straw as they move through the field, though the chopping is disabled when the straw is to be baled, and chaff collectors are sometimes used to prevent the dispersal of weed seed throughout a field.
The corn sheller was almost identical in design, with slight modifications to deal with the larger kernel size and presence of cobs. Modern-day combines can be adjusted to work with any grain crop and many unusual seed crops.
Both the older and modern machines require a good deal of effort to operate. The concave clearance, cylinder speed, fan velocity, sieve sizes, and feeding rate must be adjusted for crop conditions.
Another development in Asia
From the early 20th century, petrol or diesel-powered threshing machines, designed especially to thresh rice, the most important crop in Asia, have been developed along different lines to the modern combine.
Even after the combine was invented and became popular, a new compact-size thresher called a harvester, with wheels, still remains in use and at present it is available from a Japanese agricultural manufacturer. The compact-size machine is very convenient to handle in small terrace fields in mountain areas where a large machine, such as a combine, is not usable.
People there use this harvester with a modern compact binder. | Threshing machine | Wikipedia | 488 | 46193 | https://en.wikipedia.org/wiki/Threshing%20machine | Technology | Farm and garden machinery | null |
Preservation
A number of older threshing machines have survived into preservation. They are often to be seen in operation at live steam festivals and traction engine rallies such as the Great Dorset Steam Fair in England, and the Western Minnesota Steam Threshers Reunion in northwest Minnesota.
Musical references
Irish songwriter John Duggan immortalised the threshing machine in the song "The Old Thrashing Mill". The song has been recorded by Foster and Allen and Brendan Shine.
On the Alan Lomax collection Songs of Seduction (Rounder Select, 2000), there is a bawdy Irish folk song called "The Thrashing Machine" sung by tinker Annie O'Neil, as recorded in the early 20th century.
In his film score for Of Mice and Men (1939) and consequently in his collection Music for the Movies (1942), American composer Aaron Copland titled a section of the score "Threshing Machines," to suit a scene in the Lewis Milestone film where Curley is threatening Slim over giving May a puppy, when many of the itinerant worker men are standing around or working on threshers.
In the song "Thrasher" from the album Rust Never Sleeps, Neil Young compares the modern threshing machine's technique of separating wheat from wheat stalks to the natural forces of time that separate close friends from one another.
Threshing machines appear in Twenty One Pilots' music video for the song "House of Gold".
The song The Thrashing Machine By Chad Morgan Depicts Chadwick trying to impress a girl by showing her his threshing machine. | Threshing machine | Wikipedia | 317 | 46193 | https://en.wikipedia.org/wiki/Threshing%20machine | Technology | Farm and garden machinery | null |
A tuna (: tunas or tuna) is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max length: , weight: ) up to the Atlantic bluefin tuna (max length: , weight: ), which averages and is believed to live up to 50 years.
Tuna, opah, and mackerel sharks are the only species of fish that can maintain a body temperature higher than that of the surrounding water. An active and agile predator, the tuna has a sleek, streamlined body, and is among the fastest-swimming pelagic fish – the yellowfin tuna, for example, is capable of speeds of up to . Greatly inflated speeds can be found in early scientific reports and are still widely reported in the popular literature.
Found in warm seas, the tuna is commercially fished extensively as a food fish, and is popular as a bluewater game fish. As a result of overfishing, some tuna species, such as the southern bluefin tuna, are threatened with extinction.
Etymology
The term "tuna" comes from Spanish atún < Andalusian Arabic at-tūn, assimilated from al-tūn [Modern Arabic ] : 'tuna fish' < Middle Latin thunnus. is derived from used for the Atlantic bluefin tuna, that name in turn is ultimately derived from thýnō, meaning "to rush, dart along".
In English, tuna has been referred to as Chicken of the Sea. This name persists today in Japan, where tuna as a food can be called , literally "sea chicken".
Taxonomy
The Thunnini tribe is a monophyletic clade comprising 15 species in five genera:
family Scombridae
tribe Thunnini: tunas
genus Allothunnus: slender tunas
genus Auxis: frigate tunas
genus Euthynnus: little tunas
genus Katsuwonus: skipjack tunas
genus Thunnus: albacores and true tunas
subgenus Thunnus (Thunnus): bluefin group
subgenus Thunnus (Neothunnus): yellowfin group | Tuna | Wikipedia | 464 | 46211 | https://en.wikipedia.org/wiki/Tuna | Biology and health sciences | Acanthomorpha | null |
The cladogram is a tool for visualizing and comparing the evolutionary relationships between taxa, and is read left-to-right as if on a timeline. The following cladogram illustrates the relationship between the tunas and other tribes of the family Scombridae. For example, the cladogram illustrates that the skipjack tunas are more closely related to the true tunas than are the slender tunas (the most primitive of the tunas), and that the next nearest relatives of the tunas are the bonitos of the tribe Sardini.
True species
The "true" tunas are those that belong to the genus Thunnus. Until recently, it was thought that there were seven Thunnus species, and that Atlantic bluefin tuna and Pacific bluefin tuna were subspecies of a single species. In 1999, Collette established that based on both molecular and morphological considerations, they are in fact distinct species.
The genus Thunnus is further classified into two subgenera: Thunnus (Thunnus) (the bluefin group), and Thunnus (Neothunnus) (the yellowfin group).
|}
Other species
The Thunnini tribe also includes seven additional species of tuna across four genera. They are: | Tuna | Wikipedia | 259 | 46211 | https://en.wikipedia.org/wiki/Tuna | Biology and health sciences | Acanthomorpha | null |
{| class="wikitable"
|-
! colspan="9"| Other tuna species
|-
! style="width:10em" | Common name
! style="width:11em" | Scientific name
! Maximumlength
! Commonlength
! Maximumweight
! Maximumage
! Trophiclevel
! Source
! style="width:11em" |IUCN status
|-
| Slender tuna
| Allothunnus fallai(Serventy, 1948)
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:center;"| 3.74
| style="text-align:center;"|
| Least concern
|-
| Bullet tuna
| Auxis rochei(Risso, 1810)
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"| 5 years
| style="text-align:center;"| 4.13
| style="text-align:center;"|
| Least concern
|-
| Frigate tuna
| Auxis thazard (Lacépède, 1800)
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"| 5 years
| style="text-align:center;"| 4.34
| style="text-align:center;"|
| Least concern
|-
| Mackerel tuna,Kawakawa
| Euthynnus affinis(Cantor, 1849)
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"| 6 years
| style="text-align:center;"| 4.50
| style="text-align:center;"|
| Least concern
|-
| Little tunny
| Euthynnus alletteratus(Rafinesque, 1810)
| style="text-align:right;"| | Tuna | Wikipedia | 512 | 46211 | https://en.wikipedia.org/wiki/Tuna | Biology and health sciences | Acanthomorpha | null |
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"| 10 years
| style="text-align:center;"| 4.13
| style="text-align:center;"|
| Least concern
|-
| Black skipjack tuna
| Euthynnus lineatus(Kishinouye, 1920)
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:center;"| 3.83
| style="text-align:center;"|
| Least concern
|-
| Skipjack tuna
| Katsuwonus pelamis(Linnaeus, 1758)
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"|
| style="text-align:right;"| 6–12 yrs
| style="text-align:center;"| 3.75
| style="text-align:center;"|
| Least concern
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Biology
Description
The tuna is a sleek, elongated and streamlined fish, adapted for speed. It has two closely spaced but separated dorsal fins on its back; The first fin is "depressible" – it can be laid down, flush, in a groove that runs along its back; it is supported by spines. Seven to ten yellow finlets run from the dorsal fins to the tail, which is lunate – curved like a crescent moon – and tapered to pointy tips. A tuna's pelvic fins are located below the base of the pectoral fins. Both dorsal and pelvic fins retract when the fish is swimming fast.
The tuna's body is countershaded to camouflage itself in deeper water when seen from above, its dorsal side is generally a metallic dark blue while the ventral or under side is silvery, often with an iridescent shine. The caudal peduncle, to which the tail is attached, is quite thin, with three stabilizing horizontal keels on each side.
Physiology
Thunnus are widely but sparsely distributed throughout the oceans of the world, generally in tropical and temperate waters at latitudes ranging between about 45° north and south of the equator. All tunas are able to maintain the temperature of certain parts of their body above the temperature of ambient seawater. For example, bluefin can maintain a core body temperature of , in water as cold as . Unlike other endothermic creatures such as mammals and birds, tuna do not maintain temperature within a relatively narrow range.
Tunas achieve endothermy by conserving the heat generated through normal metabolism. In all tunas, the heart operates at ambient temperature, as it receives cooled blood, and coronary circulation is directly from the gills. The rete mirabile ("wonderful net"), the intertwining of veins and arteries in the body's periphery, allows nearly all of the metabolic heat from venous blood to be "re-claimed" and transferred to the arterial blood via a counter-current exchange system, thus mitigating the effects of surface cooling. This allows the tuna to elevate the temperatures of the highly-aerobic tissues of the skeletal muscles, eyes and brain, which supports faster swimming speeds and reduced energy expenditure, and which enables them to survive in cooler waters over a wider range of ocean environments than those of other fish. | Tuna | Wikipedia | 489 | 46211 | https://en.wikipedia.org/wiki/Tuna | Biology and health sciences | Acanthomorpha | null |
Also unlike most fish, which have white flesh, the muscle tissue of tuna ranges from pink to dark red. The red myotomal muscles derive their color from myoglobin, an oxygen-binding molecule, which tuna express in quantities far higher than most other fish. The oxygen-rich blood further enables energy delivery to their muscles.
For powerful swimming animals like dolphins and tuna, cavitation may be detrimental, because it limits their maximum swimming speed. Even if they have the power to swim faster, dolphins may have to restrict their speed, because collapsing cavitation bubbles on their tail are too painful. Cavitation also slows tuna, but for a different reason. Unlike dolphins, these fish do not feel the bubbles, because they have bony fins without nerve endings. Nevertheless, they cannot swim faster because the cavitation bubbles create a vapor film around their fins that limits their speed. Lesions have been found on tuna that are consistent with cavitation damage.
Fishing
Commerce
Tuna is an important commercial fish. The International Seafood Sustainability Foundation (ISSF) compiled a detailed scientific report on the state of global tuna stocks in 2009, which includes regular updates. According to the ISSF, the most important species for commercial and recreational tuna fisheries are yellowfin (Thunnus albacares), bigeye (T. obesus), bluefin (T. thynnus, T. orientalis, and T. macoyii), albacore (T. alalunga), and skipjack (Katsuwonus pelamis).
Based on catches from 2007, the report states:
The Australian government alleged in 2006 that Japan had illegally overfished southern bluefin by taking 12,000 to 20,000 tonnes per year instead of the agreed upon 6,000 tonnes; the value of such overfishing would be as much as US$2 billion. Such overfishing has severely damaged bluefin stocks. According to the WWF, "Japan's huge appetite for tuna will take the most sought-after stocks to the brink of commercial extinction unless fisheries agree on more rigid quotas". Japan's Fisheries Research Agency counters that Australian and New Zealand tuna fishing companies under-report their total catches of southern bluefin tuna and ignore internationally mandated total allowable catch totals. | Tuna | Wikipedia | 465 | 46211 | https://en.wikipedia.org/wiki/Tuna | Biology and health sciences | Acanthomorpha | null |
In recent years, opening day fish auctions at Tokyo's Tsukiji fish market and Toyosu Market have seen record-setting prices for bluefin tuna, reflecting market demand. In each of 2010, 2011, 2012, 2013 and 2019, new record prices have been set for a single fish – the current record is 333.6 million japanese yen (US$3.1 million) for a bluefin, or a unit price of JP¥ 1,200,000/kg (US$5,057/lb). The opening auction price for 2014 plummeted to less than 5% of the previous year's price, which had drawn complaints for climbing "way out of line". A summary of record-setting auctions are shown in the following table (highlighted values indicate new world records):
In November 2011, a different record was set when a fisherman in Massachusetts caught an tuna. It was captured inadvertently using a dragnet. Due to the laws and restrictions on tuna fishing in the United States, federal authorities impounded the fish because it was not caught with a rod and reel. Because of the tuna's deteriorated condition as a result of the trawl net, the fish sold for just under $5,000.
Methods
Besides for edible purposes, many tuna species are caught frequently as game, often for recreation or for contests in which money is awarded based on weight. Larger specimens are notorious for putting up a fight while hooked, and have been known to injure people who try to catch them, as well as damage their equipment.
Phoenician technique for trapping and catching Atlantic bluefin tuna called Almadraba, still used today in Portugal, Spain, Morocco and Italy which uses a maze of nets. In Sicily, the same method is called Tonnara.
Fish farming (cage system)
Tuna ranching
Longline fishing
Purse seines
Pole and line
Harpoon gun
Big game fishing
Fish aggregating device | Tuna | Wikipedia | 395 | 46211 | https://en.wikipedia.org/wiki/Tuna | Biology and health sciences | Acanthomorpha | null |
Association with whaling
In 2005, Nauru, defending its vote from Australian criticism at that year's meeting of the International Whaling Commission, argued that some whale species have the potential to devastate Nauru's tuna stocks, and that Nauru's food security and economy relies heavily on fishing. Despite this, Nauru does not permit whaling in its own waters and does not allow other fishing vessels to take or intentionally interact with marine mammals in its Exclusive Economic Zone. In 2010 and 2011, Nauru supported Australian proposals for a western Pacific-wide ban on tuna purse-seining in the vicinity of marine mammals – a measure which was agreed by the Western and Central Pacific Fisheries Commission at its eighth meeting in March 2012.
Association with dolphins
Dolphins swim beside several tuna species. These include yellowfin tuna in the eastern Pacific Ocean, but not albacore. Tuna schools are believed to associate themselves with dolphins for protection against sharks, which are tuna predators.
Commercial fishing vessels used to exploit this association by searching for dolphin pods. Vessels would encircle the pod with nets to catch the tuna beneath. The nets were prone to entangling dolphins, injuring or killing them. Public outcry and new government regulations, which are now monitored by NOAA have led to more dolphin-friendly methods, now generally involving lines rather than nets. There are neither universal independent inspection programs nor verification of dolphin safety, so these protections are not absolute. According to Consumers Union, the resulting lack of accountability means claims of tuna that is "dolphin safe" should be given little credence.
Fishery practices have changed to be dolphin friendly, which has caused greater bycatch including sharks, turtles and other oceanic fish. Fishermen no longer follow dolphins, but concentrate their fisheries around floating objects such as fish aggregation devices, also known as FADs, which attract large populations of other organisms. Measures taken thus far to satisfy the public demand to protect dolphins can be potentially damaging to other species as well.
Aquaculture
Increasing quantities of high-grade tuna caught at sea are reared in net pens and fed bait fish. In Australia, former fishermen raise southern bluefin tuna (Thunnus maccoyii) and another bluefin species. Farming its close relative, the Atlantic bluefin tuna, Thunnus thynnus, is beginning in the Mediterranean, North America and Japan. Hawaii approved permits for the first U.S. offshore farming of bigeye tuna in water deep in 2009. | Tuna | Wikipedia | 494 | 46211 | https://en.wikipedia.org/wiki/Tuna | Biology and health sciences | Acanthomorpha | null |
Japan is the biggest tuna consuming nation and is also the leader in tuna farming research. Japan first successfully farm-hatched and raised bluefin tuna in 1979. In 2002, it succeeded in completing the reproduction cycle and in 2007, completed a third generation. The farm breed is known as Kindai tuna. Kindai is the contraction of Kinki University in Japanese (Kinki daigaku). In 2009, Clean Seas, an Australian company which has been receiving assistance from Kinki University managed to breed southern bluefin tuna in captivity and was awarded the second place in World's Best Invention of 2009 by Time magazine.
Food
Fresh and frozen
The fresh or frozen flesh of tuna is widely regarded as a delicacy in most areas where it is shipped, being prepared in a variety of ways. When served as a steak, the meat of most species is known for its thickness and tough texture. In the U.K., supermarkets began flying in fresh tuna steaks in the late 1990s, which helped to increase the popularity of using fresh tuna in cooking; by 2009, celebrity chefs regularly featured fresh tuna in salads, wraps, and char-grilled dishes.
Served raw
Various species of tuna are often served raw in Japanese cuisine as sushi or sashimi.
Commercial sashimi tuna may have their coloration fixated by pumping carbon monoxide (CO) into bags containing the tuna, and holding it at 4 °C. For a 2-inch tuna steak, this requires 24 hours. The fish is then vacuum sealed and frozen. In Japan, color fixation using CO is prohibited.
Canned
Tuna is canned in edible oils, in brine, in water, and in various sauces. Tuna may be processed and labeled as "solid", "chunked" ("chunk") or "flaked". When tuna is canned and packaged for sale, the product is sometimes called tuna fish (U.S.), a calque (loan translation) from the German Thunfisch. Canned tuna is sometimes used as food for pets, especially cats.
Australia
Canned tuna was first produced in Australia in 1903 and quickly became popular.
In the early 1980s canned tuna in Australia was most likely southern bluefin, it was usually yellowfin, skipjack, or tongol (labelled "northern bluefin" or "longtail").
Australian standards once required cans of tuna to contain at least 51% tuna, but those regulations were dropped in 2003. The remaining weight is usually oil or water. | Tuna | Wikipedia | 506 | 46211 | https://en.wikipedia.org/wiki/Tuna | Biology and health sciences | Acanthomorpha | null |
United States
The product became more plentiful in the United States in the late 1940s. In 1950, 8,500,000 pounds of canned tuna were produced, and the U.S. Department of Agriculture classified it as a "plentiful food".
In the United States, 52% of canned tuna is used for sandwiches; 22% for tuna salads; and 15% for tuna casseroles and dried, prepackaged meal kits, such as General Mills's Tuna Helper line. Other canned tuna dishes include tuna melts (a type of sandwich where the tuna is mixed with mayonnaise and served on bread with cheese melted on top); salade niçoise (a salad made of tuna, olives, green beans, potatoes, hard-boiled eggs and anchovy dressing); and tuna burgers (served on buns).
In the United States, the Food and Drug Administration (FDA) regulates canned tuna (see part c).
Precooked
As tunas are often caught far from where they are processed, poor interim conservation can lead to spoilage. Tuna is typically gutted by hand, and later precooked for prescribed times of 45 minutes to three hours. The fish are then cleaned and filleted, canned (and sealed), with the dark lateral blood meat often separately canned for pet food (cat or dog). The sealed can is then heated under pressure (called "retort cooking") for 2–4 hours. This process kills any bacteria, but retains the histamine that may have been produced by those bacteria, and so may still taste spoiled. The international standard sets the maximum histamine level at 200 milligrams per kilogram. An Australian study of 53 varieties of unflavored canned tuna found none to exceed the safe histamine level, although some had "off" flavors.
Light and white
In some markets, depending upon the color of the flesh of the tuna species, the can is marked as "light" or "white" meat, with "light" meaning a greyish pink color and "white" meaning a light pink color. In the United States, only albacore can legally be sold in canned form as "white meat tuna"; in other countries, yellowfin is also acceptable.
Ventresca tuna
Ventresca tuna (from ventre, the Italian word for belly), is a luxury canned tuna, from the fatty bluefin tuna belly, also used in sushi as toro.
Nutrition | Tuna | Wikipedia | 510 | 46211 | https://en.wikipedia.org/wiki/Tuna | Biology and health sciences | Acanthomorpha | null |
Canned light tuna in oil is 29% protein, 8% fat, 60% water, and contains no carbohydrates, while providing 200 calories in a 100 gram reference amount (table). It is a rich source (20% or more of the Daily Value, DV) of phosphorus (44% DV) and vitamin D (45% DV), and a moderate source of iron (11% DV).
Mercury and health
Mercury content in tuna can vary widely. Among those calling for improved warnings about mercury in tuna is the American Medical Association, which adopted a policy that physicians should help make their patients more aware of the potential risks. A study published in 2008 found that mercury distribution in the meat of farmed tuna is inversely related to the lipid content, suggesting that higher lipid concentration within edible tissues of tuna raised in captivity might, other factors remaining equal, have a diluting effect on mercury content. Mackerel tuna is one species of tuna that is lower in mercury concentration than skipjack or yellowfin, but this species is known as "black meat" or "dark meat" tuna, which is a lower grade for canning because of the color, unfavorable flavor, and poor yield.
In March 2004, the United States FDA issued guidelines recommending that pregnant women, nursing mothers, and children limit their intake of tuna and other predatory fish. The Environmental Protection Agency provides guidelines on how much canned tuna is safe to eat. Roughly speaking, the guidelines recommend one can of light tuna per week for individuals weighing less than , and two cans per week for those who weigh more. In 2007, it was reported that some canned light tuna such as yellowfin tuna is significantly higher in mercury than skipjack, and caused Consumers Union and other activist groups to advise pregnant women to refrain from consuming canned tuna. In 2009, a California appeals court upheld a ruling that canned tuna does not need warning labels as the methylmercury is naturally occurring.
A January 2008 report revealed potentially dangerous levels of mercury in certain varieties of sushi tuna, reporting levels "so high that the Food and Drug Administration could take legal action to remove the fish from the market."
Management and conservation | Tuna | Wikipedia | 447 | 46211 | https://en.wikipedia.org/wiki/Tuna | Biology and health sciences | Acanthomorpha | null |
The main tuna fishery management bodies are the Western and Central Pacific Fisheries Commission, the Inter-American Tropical Tuna Commission, the Indian Ocean Tuna Commission, the International Commission for the Conservation of Atlantic Tunas, and the Commission for the Conservation of Southern Bluefin Tuna. The five gathered for the first time in Kobe, Japan in January 2007. Environmental organizations made submissions on risks to fisheries and species. The meeting concluded with an action plan drafted by some 60 countries or areas. Concrete steps include issuing certificates of origin to prevent illegal fishing and greater transparency in the setting of regional fishing quotas. The delegates were scheduled to meet at another joint meeting in January or February 2009 in Europe.
In 2010, Greenpeace International added the albacore, bigeye tuna, Pacific bluefin tuna, Atlantic bluefin tuna, southern bluefin tuna, and yellowfin tuna to its seafood red list, which are fish "commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."
Bluefin tuna have been widely accepted as being severely overfished, with some stocks at risk of collapse. According to the International Seafood Sustainability Foundation (a global, nonprofit partnership between the tuna industry, scientists, and the World Wide Fund for Nature), Indian Ocean yellowfin tuna, Pacific Ocean (eastern and western) bigeye tuna, and North Atlantic albacore tuna are all overfished. In April 2009, no stock of skipjack tuna (which makes up roughly 60% of all tuna fished worldwide) was considered to be overfished.
The BBC documentary South Pacific, which first aired in May 2009, stated that, should fishing in the Pacific continue at its current rate, populations of all tuna species could collapse within five years. It highlighted huge Japanese and European tuna fishing vessels, sent to the South Pacific international waters after overfishing their own fish stocks to the point of collapse.
A 2010 tuna fishery assessment report, released in January 2012 by the Secretariat of the Pacific Community, supported this finding, recommending that all tuna fishing should be reduced or limited to current levels and that limits on skipjack fishing be considered.
Research indicates that increasing ocean temperatures are taking a toll on the tuna in the Indian Ocean, where rapid warming of the ocean has resulted in a reduction of marine phytoplankton. The bigeye tuna catch rates have also declined abruptly during the past half century, mostly due to increased industrial fisheries, with the ocean warming adding further stress to the fish species. | Tuna | Wikipedia | 505 | 46211 | https://en.wikipedia.org/wiki/Tuna | Biology and health sciences | Acanthomorpha | null |
Sowing is the process of planting seeds. An area that has had seeds planted in it will be described as a sowed or sown area.
When sowing it is important to:
Use quality seeds
Maintain proper distance between seeds
Plant at correct depth
Ensure the soil is clean , healthy , and free of pathogens (disease causing microorganisms)
Plants which are usually sown
Among the major field crops, oats, wheat, and rye are sown, grasses and legumes are seeded and maize and soybeans are planted. In planting, wider rows (generally 75 cm (30 in) or more) are used, and the intent is to have precise; even spacing between individual seeds in the row, various mechanisms have been devised to count out individual seeds at exact intervals.
Depth of sowing
In sowing, little if any soil is placed over the seeds, as seeds can be generally sown into the soil by maintaining a planting depth of about 2-3 times the size of the seed.
Sowing types and patterns
For hand sowing, several sowing types exist; these include:
Flat sowing
Ridge sowing
Wide bed sowing
Several patterns for sowing may be used together with these types; these include:
Rows that are indented at the even rows (so that the seeds are
Symmetrical grid pattern – using the pattern described in The Garden of Cyrus placed in a crossed pattern). This method is much better, as more light may fall on the seedlings as they come out.
Types of sowing
Hand sowing
Hand sowing or (planting) is the process of casting handfuls of seed over prepared ground: broadcasting, that is, broadcast seeding (from which the technological term is derived). Usually, a drag or harrow is employed to incorporate the seed into the soil. Though labor-intensive for any but small areas, this method is still used in some situations. Practice is required to sow evenly and at the desired rate. A hand seeder can be used for sowing, though it is less of a help than it is for the smaller seeds of grasses and legumes.
Hand sowing may be combined with pre-sowing in seed trays. This allows the plants to come to strength indoors during cold periods (e.g. spring in temperate countries). | Sowing | Wikipedia | 470 | 46223 | https://en.wikipedia.org/wiki/Sowing | Technology | Agronomical techniques | null |
Seed drill
In agriculture, most seed is now sown using a seed drill, which offers greater precision; seed is sown evenly and at the desired rate. The drill also places the seed at a measured distance below the soil, so that less seed is required. The standard design uses a fluted feed metering system, which is volumetric in nature; individual seeds are not counted. Rows are typically about 10–30 cm apart, depending on the crop species and growing conditions. Several row opener types are used depending on soil type and local tradition. Grain drills are most often drawn by tractors, but can also be pulled by horses. Pickup trucks are sometimes used, since little draft is required.
A seed rate of about 100 kg of seed per hectare (2 bushels per acre) is typical, though rates vary considerably depending on crop species, soil conditions, and farmer's preference. Excessive rates can cause the crop to lodge, while too thin a rate will result in poor utilisation of the land, competition with weeds and a reduction in the yield.
Open field
Open-field planting refers to the form of sowing used historically in the agricultural context whereby fields are prepared generically and left open, as the name suggests, before being sown directly with seed. The seed is frequently left uncovered at the surface of the soil before germinating and therefore exposed to the prevailing climate and conditions like storms etc. This is in contrast to the seedbed method used more commonly in domestic gardening or more specific (modern) agricultural scenarios where the seed is applied beneath the soil surface and monitored and manually tended frequently to ensure more successful growth rates and better yields.
Pre-treatment of seed and soil before sowing
Before sowing, certain seeds first require a treatment prior to the sowing process.
This treatment may be seed scarification, stratification, seed soaking or seed cleaning with cold (or medium hot) water.
Seed soaking is generally done by placing seeds in medium hot water for at least 24 to up to 48 hours
Seed cleaning is done especially with fruit, as the flesh of the fruit around the seed can quickly become prone to attack from insects or plagues. Seed washing is generally done by submerging cleansed seeds 20 minutes in 50 degree Celsius water. This (rather hot than moderately hot) water kills any organisms that may have survived on the skin of a seed. Especially with easily infected tropical fruit such as lychees and rambutans, seed washing with high-temperature water is vital. | Sowing | Wikipedia | 508 | 46223 | https://en.wikipedia.org/wiki/Sowing | Technology | Agronomical techniques | null |
In addition to the mentioned seed pretreatments, seed germination is also assisted when a disease-free soil is used. Especially when trying to germinate difficult seed (e.g. certain tropical fruit), prior treatment of the soil (along with the usage of the most suitable soil; e.g. potting soil, prepared soil or other substrates) is vital. The two most used soil treatments are pasteurisation and sterilisation. Depending on the necessity, pasteurisation is to be preferred as this does not kill all organisms. Sterilisation can be done when trying to grow truly difficult crops. To pasteurise the soil, the soil is heated for 15 minutes in an oven of 120 °C. | Sowing | Wikipedia | 149 | 46223 | https://en.wikipedia.org/wiki/Sowing | Technology | Agronomical techniques | null |
Refrigeration is any of various types of cooling of a space, substance, or system to lower and/or maintain its temperature below the ambient one (while the removed heat is ejected to a place of higher temperature). Refrigeration is an artificial, or human-made, cooling method.
Refrigeration refers to the process by which energy, in the form of heat, is removed from a low-temperature medium and transferred to a high-temperature medium. This work of energy transfer is traditionally driven by mechanical means (whether ice or electromechanical machines), but it can also be driven by heat, magnetism, electricity, laser, or other means. Refrigeration has many applications, including household refrigerators, industrial freezers, cryogenics, and air conditioning. Heat pumps may use the heat output of the refrigeration process, and also may be designed to be reversible, but are otherwise similar to air conditioning units.
Refrigeration has had a large impact on industry, lifestyle, agriculture, and settlement patterns. The idea of preserving food dates back to human prehistory, but for thousands of years humans were limited regarding the means of doing so. They used curing via salting and drying, and they made use of natural coolness in caves, root cellars, and winter weather, but other means of cooling were unavailable. In the 19th century, they began to make use of the ice trade to develop cold chains. In the late 19th through mid-20th centuries, mechanical refrigeration was developed, improved, and greatly expanded in its reach. Refrigeration has thus rapidly evolved in the past century, from ice harvesting to temperature-controlled rail cars, refrigerator trucks, and ubiquitous refrigerators and freezers in both stores and homes in many countries. The introduction of refrigerated rail cars contributed to the settlement of areas that were not on earlier main transport channels such as rivers, harbors, or valley trails. | Refrigeration | Wikipedia | 406 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
These new settlement patterns sparked the building of large cities which are able to thrive in areas that were otherwise thought to be inhospitable, such as Houston, Texas, and Las Vegas, Nevada. In most developed countries, cities are heavily dependent upon refrigeration in supermarkets in order to obtain their food for daily consumption. The increase in food sources has led to a larger concentration of agricultural sales coming from a smaller percentage of farms. Farms today have a much larger output per person in comparison to the late 1800s. This has resulted in new food sources available to entire populations, which has had a large impact on the nutrition of society.
History
Earliest forms of cooling
The seasonal harvesting of snow and ice is an ancient practice estimated to have begun earlier than 1000 BC. A Chinese collection of lyrics from this time period known as the Sleaping, describes religious ceremonies for filling and emptying ice cellars. However, little is known about the construction of these ice cellars or the purpose of the ice. The next ancient society to record the harvesting of ice may have been the Jews in the book of Proverbs, which reads, "As the cold of snow in the time of harvest, so is a faithful messenger to them who sent him." Historians have interpreted this to mean that the Jews used ice to cool beverages rather than to preserve food. Other ancient cultures such as the Greeks and the Romans dug large snow pits insulated with grass, chaff, or branches of trees as cold storage. Like the Jews, the Greeks and Romans did not use ice and snow to preserve food, but primarily as a means to cool beverages. Egyptians cooled water by evaporation in shallow earthen jars on the roofs of their houses at night. The ancient people of India used this same concept to produce ice. The Persians stored ice in a pit called a Yakhchal and may have been the first group of people to use cold storage to preserve food. In the Australian outback before a reliable electricity supply was available many farmers used a Coolgardie safe, consisting of a box frame with hessian (burlap) sides soaked in water. The water would evaporate and thereby cool the interior air, allowing many perishables such as fruit, butter, and cured meats to be kept.
Ice harvesting | Refrigeration | Wikipedia | 464 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
Before 1830, few Americans used ice to refrigerate foods due to a lack of ice-storehouses and iceboxes. As these two things became more widely available, individuals used axes and saws to harvest ice for their storehouses. This method proved to be difficult, dangerous, and certainly did not resemble anything that could be duplicated on a commercial scale.
Despite the difficulties of harvesting ice, Frederic Tudor thought that he could capitalize on this new commodity by harvesting ice in New England and shipping it to the Caribbean islands as well as the southern states. In the beginning, Tudor lost thousands of dollars, but eventually turned a profit as he constructed icehouses in Charleston, Virginia and in the Cuban port town of Havana. These icehouses as well as better insulated ships helped reduce ice wastage from 66% to 8%. This efficiency gain influenced Tudor to expand his ice market to other towns with icehouses such as New Orleans and Savannah. This ice market further expanded as harvesting ice became faster and cheaper after one of Tudor's suppliers, Nathaniel Wyeth, invented a horse-drawn ice cutter in 1825. This invention as well as Tudor's success inspired others to get involved in the ice trade and the ice industry grew.
Ice became a mass-market commodity by the early 1830s with the price of ice dropping from six cents per pound to a half of a cent per pound. In New York City, ice consumption increased from 12,000 tons in 1843 to 100,000 tons in 1856. Boston's consumption leapt from 6,000 tons to 85,000 tons during that same period. Ice harvesting created a "cooling culture" as majority of people used ice and iceboxes to store their dairy products, fish, meat, and even fruits and vegetables. These early cold storage practices paved the way for many Americans to accept the refrigeration technology that would soon take over the country.
Refrigeration research
The history of artificial refrigeration began when Scottish professor William Cullen designed a small refrigerating machine in 1755. Cullen used a pump to create a partial vacuum over a container of diethyl ether, which then boiled, absorbing heat from the surrounding air. The experiment even created a small amount of ice, but had no practical application at that time. | Refrigeration | Wikipedia | 463 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
In 1758, Benjamin Franklin and John Hadley, professor of chemistry, collaborated on a project investigating the principle of evaporation as a means to rapidly cool an object at Cambridge University, England. They confirmed that the evaporation of highly volatile liquids, such as alcohol and ether, could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with the bulb of a mercury thermometer as their object and with a bellows used to quicken the evaporation; they lowered the temperature of the thermometer bulb down to , while the ambient temperature was . They noted that soon after they passed the freezing point of water , a thin film of ice formed on the surface of the thermometer's bulb and that the ice mass was about a thick when they stopped the experiment upon reaching . Franklin wrote, "From this experiment, one may see the possibility of freezing a man to death on a warm summer's day". In 1805, American inventor Oliver Evans described a closed vapor-compression refrigeration cycle for the production of ice by ether under vacuum.
In 1820, the English scientist Michael Faraday liquefied ammonia and other gases by using high pressures and low temperatures, and in 1834, an American expatriate to Great Britain, Jacob Perkins, built the first working vapor-compression refrigeration system in the world. It was a closed-cycle that could operate continuously, as he described in his patent:
I am enabled to use volatile fluids for the purpose of producing the cooling or freezing of fluids, and yet at the same time constantly condensing such volatile fluids, and bringing them again into operation without waste.
His prototype system worked although it did not succeed commercially.
In 1842, a similar attempt was made by American physician, John Gorrie, who built a working prototype, but it was a commercial failure. Like many of the medical experts during this time, Gorrie thought too much exposure to tropical heat led to mental and physical degeneration, as well as the spread of diseases such as malaria. He conceived the idea of using his refrigeration system to cool the air for comfort in homes and hospitals to prevent disease. American engineer Alexander Twining took out a British patent in 1850 for a vapour compression system that used ether. | Refrigeration | Wikipedia | 470 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
The first practical vapour-compression refrigeration system was built by James Harrison, a British journalist who had emigrated to Australia. His 1856 patent was for a vapour-compression system using ether, alcohol, or ammonia. He built a mechanical ice-making machine in 1851 on the banks of the Barwon River at Rocky Point in Geelong, Victoria, and his first commercial ice-making machine followed in 1854. Harrison also introduced commercial vapour-compression refrigeration to breweries and meat-packing houses, and by 1861, a dozen of his systems were in operation. He later entered the debate of how to compete against the American advantage of unrefrigerated beef sales to the United Kingdom. In 1873 he prepared the sailing ship Norfolk for an experimental beef shipment to the United Kingdom, which used a cold room system instead of a refrigeration system. The venture was a failure as the ice was consumed faster than expected.
The first gas absorption refrigeration system using gaseous ammonia dissolved in water (referred to as "aqua ammonia") was developed by Ferdinand Carré of France in 1859 and patented in 1860. Carl von Linde, an engineer specializing in steam locomotives and professor of engineering at the Technological University of Munich in Germany, began researching refrigeration in the 1860s and 1870s in response to demand from brewers for a technology that would allow year-round, large-scale production of lager; he patented an improved method of liquefying gases in 1876. His new process made possible using gases such as ammonia, sulfur dioxide (SO2) and methyl chloride (CH3Cl) as refrigerants and they were widely used for that purpose until the late 1920s.
Thaddeus Lowe, an American balloonist, held several patents on ice-making machines. His "Compression Ice Machine" would revolutionize the cold-storage industry. In 1869, he and other investors purchased an old steamship onto which they loaded one of Lowe's refrigeration units and began shipping fresh fruit from New York to the Gulf Coast area, and fresh meat from Galveston, Texas back to New York, but because of Lowe's lack of knowledge about shipping, the business was a costly failure.
Commercial use | Refrigeration | Wikipedia | 452 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
In 1842, John Gorrie created a system capable of refrigerating water to produce ice. Although it was a commercial failure, it inspired scientists and inventors around the world. France's Ferdinand Carre was one of the inspired and he created an ice producing system that was simpler and smaller than that of Gorrie. During the Civil War, cities such as New Orleans could no longer get ice from New England via the coastal ice trade. Carre's refrigeration system became the solution to New Orleans' ice problems and, by 1865, the city had three of Carre's machines. In 1867, in San Antonio, Texas, a French immigrant named Andrew Muhl built an ice-making machine to help service the expanding beef industry before moving it to Waco in 1871. In 1873, the patent for this machine was contracted by the Columbus Iron Works, a company acquired by the W.C. Bradley Co., which went on to produce the first commercial ice-makers in the US.
By the 1870s, breweries had become the largest users of harvested ice. Though the ice-harvesting industry had grown immensely by the turn of the 20th century, pollution and sewage had begun to creep into natural ice, making it a problem in the metropolitan suburbs. Eventually, breweries began to complain of tainted ice. Public concern for the purity of water, from which ice was formed, began to increase in the early 1900s with the rise of germ theory. Numerous media outlets published articles connecting diseases such as typhoid fever with natural ice consumption. This caused ice harvesting to become illegal in certain areas of the country. All of these scenarios increased the demands for modern refrigeration and manufactured ice. Ice producing machines like that of Carre's and Muhl's were looked to as means of producing ice to meet the needs of grocers, farmers, and food shippers.
Refrigerated railroad cars were introduced in the US in the 1840s for short-run transport of dairy products, but these used harvested ice to maintain a cool temperature. | Refrigeration | Wikipedia | 420 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
The new refrigerating technology first met with widespread industrial use as a means to freeze meat supplies for transport by sea in reefer ships from the British Dominions and other countries to the British Isles. Although not actually the first to achieve successful transportation of frozen goods overseas (the Strathleven had arrived at the London docks on 2 February 1880 with a cargo of frozen beef, mutton and butter from Sydney and Melbourne ), the breakthrough is often attributed to William Soltau Davidson, an entrepreneur who had emigrated to New Zealand. Davidson thought that Britain's rising population and meat demand could mitigate the slump in world wool markets that was heavily affecting New Zealand. After extensive research, he commissioned the Dunedin to be refitted with a compression refrigeration unit for meat shipment in 1881. On February 15, 1882, the Dunedin sailed for London with what was to be the first commercially successful refrigerated shipping voyage, and the foundation of the refrigerated meat industry.
The Times commented "Today we have to record such a triumph over physical difficulties, as would have been incredible, even unimaginable, a very few days ago...". The Marlborough—sister ship to the Dunedin – was immediately converted and joined the trade the following year, along with the rival New Zealand Shipping Company vessel Mataurua, while the German Steamer Marsala began carrying frozen New Zealand lamb in December 1882. Within five years, 172 shipments of frozen meat were sent from New Zealand to the United Kingdom, of which only 9 had significant amounts of meat condemned. Refrigerated shipping also led to a broader meat and dairy boom in Australasia and South America. J & E Hall of Dartford, England outfitted the SS Selembria with a vapor compression system to bring 30,000 carcasses of mutton from the Falkland Islands in 1886. In the years ahead, the industry rapidly expanded to Australia, Argentina and the United States.
By the 1890s, refrigeration played a vital role in the distribution of food. The meat-packing industry relied heavily on natural ice in the 1880s and continued to rely on manufactured ice as those technologies became available. By 1900, the meat-packing houses of Chicago had adopted ammonia-cycle commercial refrigeration. By 1914, almost every location used artificial refrigeration. The major meat packers, Armour, Swift, and Wilson, had purchased the most expensive units which they installed on train cars and in branch houses and storage facilities in the more remote distribution areas. | Refrigeration | Wikipedia | 512 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
By the middle of the 20th century, refrigeration units were designed for installation on trucks or lorries. Refrigerated vehicles are used to transport perishable goods, such as frozen foods, fruit and vegetables, and temperature-sensitive chemicals. Most modern refrigerators keep the temperature between –40 and –20 °C, and have a maximum payload of around 24,000 kg gross weight (in Europe).
Although commercial refrigeration quickly progressed, it had limitations that prevented it from moving into the household. First, most refrigerators were far too large. Some of the commercial units being used in 1910 weighed between five and two hundred tons. Second, commercial refrigerators were expensive to produce, purchase, and maintain. Lastly, these refrigerators were unsafe. It was not uncommon for commercial refrigerators to catch fire, explode, or leak toxic gases. Refrigeration did not become a household technology until these three challenges were overcome.
Home and consumer use
During the early 1800s, consumers preserved their food by storing food and ice purchased from ice harvesters in iceboxes. In 1803, Thomas Moore patented a metal-lined butter-storage tub which became the prototype for most iceboxes. These iceboxes were used until nearly 1910 and the technology did not progress. In fact, consumers that used the icebox in 1910 faced the same challenge of a moldy and stinky icebox that consumers had in the early 1800s.
General Electric (GE) was one of the first companies to overcome these challenges. In 1911, GE released a household refrigeration unit that was powered by gas. The use of gas eliminated the need for an electric compressor motor and decreased the size of the refrigerator. However, electric companies that were customers of GE did not benefit from a gas-powered unit. Thus, GE invested in developing an electric model. In 1927, GE released the Monitor Top, the first refrigerator to run on electricity. | Refrigeration | Wikipedia | 392 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
In 1930, Frigidaire, one of GE's main competitors, synthesized Freon. With the invention of synthetic refrigerants based mostly on a chlorofluorocarbon (CFC) chemical, safer refrigerators were possible for home and consumer use. Freon led to the development of smaller, lighter, and cheaper refrigerators. The average price of a refrigerator dropped from $275 to $154 with the synthesis of Freon. This lower price allowed ownership of refrigerators in American households to exceed 50% by 1940. Freon is a trademark of the DuPont Corporation and refers to these CFCs, and later hydro chlorofluorocarbon (HCFC) and hydro fluorocarbon (HFC), refrigerants developed in the late 1920s. These refrigerants were considered — at the time — to be less harmful than the commonly-used refrigerants of the time, including methyl formate, ammonia, methyl chloride, and sulfur dioxide. The intent was to provide refrigeration equipment for home use without danger. These CFC refrigerants answered that need. In the 1970s, though, the compounds were found to be reacting with atmospheric ozone, an important protection against solar ultraviolet radiation, and their use as a refrigerant worldwide was curtailed in the Montreal Protocol of 1987.
Impact on settlement patterns in the United States of America
In the last century, refrigeration allowed new settlement patterns to emerge. This new technology has allowed for new areas to be settled that are not on a natural channel of transport such as a river, valley trail or harbor that may have otherwise not been settled. Refrigeration has given opportunities to early settlers to expand westward and into rural areas that were unpopulated. These new settlers with rich and untapped soil saw opportunity to profit by sending raw goods to the eastern cities and states. In the 20th century, refrigeration has made "Galactic Cities" such as Dallas, Phoenix, and Los Angeles possible. | Refrigeration | Wikipedia | 411 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
The refrigerated rail car (refrigerated van or refrigerator car), along with the dense railroad network, became an exceedingly important link between the marketplace and the farm allowing for a national opportunity rather than a just a regional one. Before the invention of the refrigerated rail car, it was impossible to ship perishable food products long distances. The beef packing industry made the first demand push for refrigeration cars. The railroad companies were slow to adopt this new invention because of their heavy investments in cattle cars, stockyards, and feedlots. Refrigeration cars were also complex and costly compared to other rail cars, which also slowed the adoption of the refrigerated rail car. After the slow adoption of the refrigerated car, the beef packing industry dominated the refrigerated rail car business with their ability to control ice plants and the setting of icing fees. The United States Department of Agriculture estimated that, in 1916, over sixty-nine percent of the cattle killed in the country was done in plants involved in interstate trade. The same companies that were also involved in the meat trade later implemented refrigerated transport to include vegetables and fruit. The meat packing companies had much of the expensive machinery, such as refrigerated cars, and cold storage facilities that allowed for them to effectively distribute all types of perishable goods. During World War I, a national refrigerator car pool was established by the United States Administration to deal with problem of idle cars and was later continued after the war. The idle car problem was the problem of refrigeration cars sitting pointlessly in between seasonal harvests. This meant that very expensive cars sat in rail yards for a good portion of the year while making no revenue for the car's owner. The car pool was a system where cars were distributed to areas as crops matured ensuring maximum use of the cars. Refrigerated rail cars moved eastward from vineyards, orchards, fields, and gardens in western states to satisfy Americas consuming market in the east. The refrigerated car made it possible to transport perishable crops hundreds and even thousands of kilometres or miles. The most noticeable effect the car gave was a regional specialization of vegetables and fruits. The refrigeration rail car was widely used for the transportation of perishable goods up until the 1950s | Refrigeration | Wikipedia | 480 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
By the 1960s, the nation's interstate highway system was adequately complete allowing for trucks to carry the majority of the perishable food loads and to push out the old system of the refrigerated rail cars | Refrigeration | Wikipedia | 43 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
Expansion west and into rural areas
The widespread use of refrigeration allowed for a vast amount of new agricultural opportunities to open up in the United States. New markets emerged throughout the United States in areas that were previously uninhabited and far-removed from heavily populated areas. New agricultural opportunity presented itself in areas that were considered rural, such as states in the south and in the west. Shipments on a large scale from the south and California were both made around the same time, although natural ice was used from the Sierras in California rather than manufactured ice in the south. Refrigeration allowed for many areas to specialize in the growing of specific fruits. California specialized in several fruits, grapes, peaches, pears, plums, and apples, while Georgia became famous for specifically its peaches. In California, the acceptance of the refrigerated rail cars led to an increase of car loads from 4,500 carloads in 1895 to between 8,000 and 10,000 carloads in 1905. The Gulf States, Arkansas, Missouri and Tennessee entered into strawberry production on a large-scale while Mississippi became the center of the tomato industry. New Mexico, Colorado, Arizona, and Nevada grew cantaloupes. Without refrigeration, this would have not been possible. By 1917, well-established fruit and vegetable areas that were close to eastern markets felt the pressure of competition from these distant specialized centers. Refrigeration was not limited to meat, fruit and vegetables but it also encompassed dairy product and dairy farms. In the early twentieth century, large cities got their dairy supply from farms as far as . Dairy products were not as easily transported over great distances like fruits and vegetables due to greater perishability. Refrigeration made production possible in the west far from eastern markets, so much in fact that dairy farmers could pay transportation cost and still undersell their eastern competitors. Refrigeration and the refrigerated rail gave opportunity to areas with rich soil far from natural channel of transport such as a river, valley trail or harbors. | Refrigeration | Wikipedia | 417 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
Rise of the galactic city
"Edge city" was a term coined by Joel Garreau, whereas the term "galactic city" was coined by Lewis Mumford. These terms refer to a concentration of business, shopping, and entertainment outside a traditional downtown or central business district in what had previously been a residential or rural area. There were several factors contributing to the growth of these cities such as Los Angeles, Las Vegas, Houston, and Phoenix. The factors that contributed to these large cities include reliable automobiles, highway systems, refrigeration, and agricultural production increases. Large cities such as the ones mentioned above have not been uncommon in history, but what separates these cities from the rest are that these cities are not along some natural channel of transport, or at some crossroad of two or more channels such as a trail, harbor, mountain, river, or valley. These large cities have been developed in areas that only a few hundred years ago would have been uninhabitable. Without a cost efficient way of cooling air and transporting water and food from great distances, these large cities would have never developed. The rapid growth of these cities was influenced by refrigeration and an agricultural productivity increase, allowing more distant farms to effectively feed the population.
Impact on agriculture and food production
Agriculture's role in developed countries has drastically changed in the last century due to many factors, including refrigeration. Statistics from the 2007 census gives information on the large concentration of agricultural sales coming from a small portion of the existing farms in the United States today. This is a partial result of the market created for the frozen meat trade by the first successful shipment of frozen sheep carcasses coming from New Zealand in the 1880s. As the market continued to grow, regulations on food processing and quality began to be enforced. Eventually, electricity was introduced into rural homes in the United States, which allowed refrigeration technology to continue to expand on the farm, increasing output per person. Today, refrigeration's use on the farm reduces humidity levels, avoids spoiling due to bacterial growth, and assists in preservation. | Refrigeration | Wikipedia | 426 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
Demographics
The introduction of refrigeration and evolution of additional technologies drastically changed agriculture in the United States. During the beginning of the 20th century, farming was a common occupation and lifestyle for United States citizens, as most farmers actually lived on their farm. In 1935, there were 6.8 million farms in the United States and a population of 127 million. Yet, while the United States population has continued to climb, citizens pursuing agriculture continue to decline. Based on the 2007 US Census, less than one percent of a population of 310 million people claim farming as an occupation today. However, the increasing population has led to an increasing demand for agricultural products, which is met through a greater variety of crops, fertilizers, pesticides, and improved technology. Improved technology has decreased the risk and time involved for agricultural management and allows larger farms to increase their output per person to meet society's demand.
Meat packing and trade
Prior to 1882, the South Island of New Zealand had been experimenting with sowing grass and crossbreeding sheep, which immediately gave their farmers economic potential in the exportation of meat. In 1882, the first successful shipment of sheep carcasses was sent from Port Chalmers in Dunedin, New Zealand, to London. By the 1890s, the frozen meat trade became increasingly more profitable in New Zealand, especially in Canterbury, where 50% of exported sheep carcasses came from in 1900. It was not long before Canterbury meat was known for the highest quality, creating a demand for New Zealand meat around the world. In order to meet this new demand, the farmers improved their feed so sheep could be ready for the slaughter in only seven months. This new method of shipping led to an economic boom in New Zealand by the mid 1890s.
In the United States, the Meat Inspection Act of 1891 was put in place in the United States because local butchers felt the refrigerated railcar system was unwholesome. When meat packing began to take off, consumers became nervous about the quality of the meat for consumption. Upton Sinclair's 1906 novel The Jungle brought negative attention to the meat packing industry, by drawing to light unsanitary working conditions and processing of diseased animals. The book caught the attention of President Theodore Roosevelt, and the 1906 Meat Inspection Act was put into place as an amendment to the Meat Inspection Act of 1891. This new act focused on the quality of the meat and environment it is processed in. | Refrigeration | Wikipedia | 491 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
Electricity in rural areas
In the early 1930s, 90 percent of the urban population of the United States had electric power, in comparison to only 10 percent of rural homes. At the time, power companies did not feel that extending power to rural areas (rural electrification) would produce enough profit to make it worth their while. However, in the midst of the Great Depression, President Franklin D. Roosevelt realized that rural areas would continue to lag behind urban areas in both poverty and production if they were not electrically wired. On May 11, 1935, the president signed an executive order called the Rural Electrification Administration, also known as REA. The agency provided loans to fund electric infrastructure in the rural areas. In just a few years, 300,000 people in rural areas of the United States had received power in their homes.
While electricity dramatically improved working conditions on farms, it also had a large impact on the safety of food production. Refrigeration systems were introduced to the farming and food distribution processes, which helped in food preservation and kept food supplies safe. Refrigeration also allowed for shipment of perishable commodities throughout the United States. As a result, United States farmers quickly became the most productive in the world, and entire new food systems arose.
Farm use
In order to reduce humidity levels and spoiling due to bacterial growth, refrigeration is used for meat, produce, and dairy processing in farming today. Refrigeration systems are used the heaviest in the warmer months for farming produce, which must be cooled as soon as possible in order to meet quality standards and increase the shelf life. Meanwhile, dairy farms refrigerate milk year round to avoid spoiling. | Refrigeration | Wikipedia | 339 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
Effects on lifestyle and diet
In the late 19th Century and into the very early 20th Century, except for staple foods (sugar, rice, and beans) that needed no refrigeration, the available foods were affected heavily by the seasons and what could be grown locally. Refrigeration has removed these limitations. Refrigeration played a large part in the feasibility and then popularity of the modern supermarket. Fruits and vegetables out of season, or grown in distant locations, are now available at relatively low prices. Refrigerators have led to a huge increase in meat and dairy products as a portion of overall supermarket sales. As well as changing the goods purchased at the market, the ability to store these foods for extended periods of time has led to an increase in leisure time. Prior to the advent of the household refrigerator, people would have to shop on a daily basis for the supplies needed for their meals.
Impact on nutrition
The introduction of refrigeration allowed for the hygienic handling and storage of perishables, and as such, promoted output growth, consumption, and the availability of nutrition. The change in our method of food preservation moved us away from salts to a more manageable sodium level. The ability to move and store perishables such as meat and dairy led to a 1.7% increase in dairy consumption and overall protein intake by 1.25% annually in the US after the 1890s.
People were not only consuming these perishables because it became easier for they themselves to store them, but because the innovations in refrigerated transportation and storage led to less spoilage and waste, thereby driving the prices of these products down. Refrigeration accounts for at least 5.1% of the increase in adult stature (in the US) through improved nutrition, and when the indirect effects associated with improvements in the quality of nutrients and the reduction in illness is additionally factored in, the overall impact becomes considerably larger. Recent studies have also shown a negative relationship between the number of refrigerators in a household and the rate of gastric cancer mortality. | Refrigeration | Wikipedia | 418 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
Current applications of refrigeration
Probably the most widely used current applications of refrigeration are for air conditioning of private homes and public buildings, and refrigerating foodstuffs in homes, restaurants and large storage warehouses. The use of refrigerators and walk-in coolers and freezers in kitchens, factories and warehouses for storing and processing fruits and vegetables has allowed adding fresh salads to the modern diet year round, and storing fish and meats safely for long periods.
The optimum temperature range for perishable food storage is .
In commerce and manufacturing, there are many uses for refrigeration. Refrigeration is used to liquefy gases – oxygen, nitrogen, propane, and methane, for example. In compressed air purification, it is used to condense water vapor from compressed air to reduce its moisture content. In oil refineries, chemical plants, and petrochemical plants, refrigeration is used to maintain certain processes at their needed low temperatures (for example, in alkylation of butenes and butane to produce a high-octane gasoline component). Metal workers use refrigeration to temper steel and cutlery. When transporting temperature-sensitive foodstuffs and other materials by trucks, trains, airplanes and seagoing vessels, refrigeration is a necessity.
Dairy products are constantly in need of refrigeration, and it was only discovered in the past few decades that eggs needed to be refrigerated during shipment rather than waiting to be refrigerated after arrival at the grocery store. Meats, poultry and fish all must be kept in climate-controlled environments before being sold. Refrigeration also helps keep fruits and vegetables edible longer.
One of the most influential uses of refrigeration was in the development of the sushi/sashimi industry in Japan. Before the discovery of refrigeration, many sushi connoisseurs were at risk of contracting diseases. The dangers of unrefrigerated sashimi were not brought to light for decades due to the lack of research and healthcare distribution across rural Japan. Around mid-century, the Zojirushi corporation, based in Kyoto, made breakthroughs in refrigerator designs, making refrigerators cheaper and more accessible for restaurant proprietors and the general public.
Methods of refrigeration
Methods of refrigeration can be classified as non-cyclic, cyclic, thermoelectric and magnetic.
Non-cyclic refrigeration | Refrigeration | Wikipedia | 508 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
This refrigeration method cools a contained area by melting ice, or by sublimating dry ice. Perhaps the simplest example of this is a portable cooler, where items are put in it, then ice is poured over the top. Regular ice can maintain temperatures near, but not below the freezing point, unless salt is used to cool the ice down further (as in a traditional ice-cream maker). Dry ice can reliably bring the temperature well below water freezing point.
Cyclic refrigeration
This consists of a refrigeration cycle, where heat is removed from a low-temperature space or source and rejected to a high-temperature sink with the help of external work, and its inverse, the thermodynamic power cycle. In the power cycle, heat is supplied from a high-temperature source to the engine, part of the heat being used to produce work and the rest being rejected to a low-temperature sink. This satisfies the second law of thermodynamics.
A refrigeration cycle describes the changes that take place in the refrigerant as it alternately absorbs and rejects heat as it circulates through a refrigerator. It is also applied to heating, ventilation, and air conditioning HVACR work, when describing the "process" of refrigerant flow through an HVACR unit, whether it is a packaged or split system.
Heat naturally flows from hot to cold. Work is applied to cool a living space or storage volume by pumping heat from a lower temperature heat source into a higher temperature heat sink. Insulation is used to reduce the work and energy needed to achieve and maintain a lower temperature in the cooled space. The operating principle of the refrigeration cycle was described mathematically by Sadi Carnot in 1824 as a heat engine.
The most common types of refrigeration systems use the reverse-Rankine vapor-compression refrigeration cycle, although absorption heat pumps are used in a minority of applications.
Cyclic refrigeration can be classified as:
Vapor cycle, and
Gas cycle
Vapor cycle refrigeration can further be classified as:
Vapor-compression refrigeration
Sorption Refrigeration
Vapor-absorption refrigeration
Adsorption refrigeration
Vapor-compression cycle | Refrigeration | Wikipedia | 467 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
The vapor-compression cycle is used in most household refrigerators as well as in many large commercial and industrial refrigeration systems. Figure 1 provides a schematic diagram of the components of a typical vapor-compression refrigeration system.
The thermodynamics of the cycle can be analyzed on a diagram as shown in Figure 2. In this cycle, a circulating refrigerant such as a low boiling hydrocarbon or hydrofluorocarbons enters the compressor as a vapour. From point 1 to point 2, the vapor is compressed at constant entropy and exits the compressor as a vapor at a higher temperature, but still below the vapor pressure at that temperature. From point 2 to point 3 and on to point 4, the vapor travels through the condenser which cools the vapour until it starts condensing, and then condenses the vapor into a liquid by removing additional heat at constant pressure and temperature. Between points 4 and 5, the liquid refrigerant goes through the expansion valve (also called a throttle valve) where its pressure abruptly decreases, causing flash evaporation and auto-refrigeration of, typically, less than half of the liquid.
That results in a mixture of liquid and vapour at a lower temperature and pressure as shown at point 5. The cold liquid-vapor mixture then travels through the evaporator coil or tubes and is completely vaporized by cooling the warm air (from the space being refrigerated) being blown by a fan across the evaporator coil or tubes. The resulting refrigerant vapour returns to the compressor inlet at point 1 to complete the thermodynamic cycle.
The above discussion is based on the ideal vapour-compression refrigeration cycle, and does not take into account real-world effects like frictional pressure drop in the system, slight thermodynamic irreversibility during the compression of the refrigerant vapor, or non-ideal gas behavior, if any. Vapor compression refrigerators can be arranged in two stages in cascade refrigeration systems, with the second stage cooling the condenser of the first stage. This can be used for achieving very low temperatures.
More information about the design and performance of vapor-compression refrigeration systems is available in the classic Perry's Chemical Engineers' Handbook.
Sorption cycle
Absorption cycle | Refrigeration | Wikipedia | 488 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
In the early years of the twentieth century, the vapor absorption cycle using water-ammonia systems or LiBr-water was popular and widely used. After the development of the vapor compression cycle, the vapor absorption cycle lost much of its importance because of its low coefficient of performance (about one fifth of that of the vapor compression cycle). Today, the vapor absorption cycle is used mainly where fuel for heating is available but electricity is not, such as in recreational vehicles that carry LP gas. It is also used in industrial environments where plentiful waste heat overcomes its inefficiency.
The absorption cycle is similar to the compression cycle, except for the method of raising the pressure of the refrigerant vapor. In the absorption system, the compressor is replaced by an absorber which dissolves the refrigerant in a suitable liquid, a liquid pump which raises the pressure and a generator which, on heat addition, drives off the refrigerant vapor from the high-pressure liquid. Some work is needed by the liquid pump but, for a given quantity of refrigerant, it is much smaller than needed by the compressor in the vapor compression cycle. In an absorption refrigerator, a suitable combination of refrigerant and absorbent is used. The most common combinations are ammonia (refrigerant) with water (absorbent), and water (refrigerant) with lithium bromide (absorbent).
Adsorption cycle
The main difference with absorption cycle, is that in adsorption cycle, the refrigerant (adsorbate) could be ammonia, water, methanol, etc., while the adsorbent is a solid, such as silica gel, activated carbon, or zeolite, unlike in the absorption cycle where absorbent is liquid.
The reason adsorption refrigeration technology has been extensively researched in recent 30 years lies in that the operation of an adsorption refrigeration system is often noiseless, non-corrosive and environment friendly.
Gas cycle
When the working fluid is a gas that is compressed and expanded but does not change phase, the refrigeration cycle is called a gas cycle. Air is most often this working fluid. As there is no condensation and evaporation intended in a gas cycle, components corresponding to the condenser and evaporator in a vapor compression cycle are the hot and cold gas-to-gas heat exchangers in gas cycles. | Refrigeration | Wikipedia | 505 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
The gas cycle is less efficient than the vapor compression cycle because the gas cycle works on the reverse Brayton cycle instead of the reverse Rankine cycle. As such, the working fluid does not receive and reject heat at constant temperature. In the gas cycle, the refrigeration effect is equal to the product of the specific heat of the gas and the rise in temperature of the gas in the low temperature side. Therefore, for the same cooling load, a gas refrigeration cycle needs a large mass flow rate and is bulky.
Because of their lower efficiency and larger bulk, air cycle coolers are not often used nowadays in terrestrial cooling devices. However, the air cycle machine is very common on gas turbine-powered jet aircraft as cooling and ventilation units, because compressed air is readily available from the engines' compressor sections. Such units also serve the purpose of pressurizing the aircraft.
Thermoelectric refrigeration
Thermoelectric cooling uses the Peltier effect to create a heat flux between the junction of two types of material. This effect is commonly used in camping and portable coolers and for cooling electronic components and small instruments. Peltier coolers are often used where a traditional vapor-compression cycle refrigerator would be impractical or take up too much space, and in cooled image sensors as an easy, compact and lightweight, if inefficient, way to achieve very low temperatures, using two or more stage peltier coolers arranged in a cascade refrigeration configuration, meaning that two or more Peltier elements are stacked on top of each other, with each stage being larger than the one before it, in order to extract more heat and waste heat generated by the previous stages. Peltier cooling has a low COP (efficiency) when compared with that of the vapor-compression cycle, so it emits more waste heat (heat generated by the Peltier element or cooling mechanism) and consumes more power for a given cooling capacity.
Magnetic refrigeration
Magnetic refrigeration, or adiabatic demagnetization, is a cooling technology based on the magnetocaloric effect, an intrinsic property of magnetic solids. The refrigerant is often a paramagnetic salt, such as cerium magnesium nitrate. The active magnetic dipoles in this case are those of the electron shells of the paramagnetic atoms. | Refrigeration | Wikipedia | 488 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
A strong magnetic field is applied to the refrigerant, forcing its various magnetic dipoles to align and putting these degrees of freedom of the refrigerant into a state of lowered entropy. A heat sink then absorbs the heat released by the refrigerant due to its loss of entropy. Thermal contact with the heat sink is then broken so that the system is insulated, and the magnetic field is switched off. This increases the heat capacity of the refrigerant, thus decreasing its temperature below the temperature of the heat sink.
Because few materials exhibit the needed properties at room temperature, applications have so far been limited to cryogenics and research.
Other methods
Other methods of refrigeration include the air cycle machine used in aircraft; the vortex tube used for spot cooling, when compressed air is available; and thermoacoustic refrigeration using sound waves in a pressurized gas to drive heat transfer and heat exchange; steam jet cooling popular in the early 1930s for air conditioning large buildings; thermoelastic cooling using a smart metal alloy stretching and relaxing. Many Stirling cycle heat engines can be run backwards to act as a refrigerator, and therefore these engines have a niche use in cryogenics. In addition, there are other types of cryocoolers such as Gifford-McMahon coolers, Joule-Thomson coolers, pulse-tube refrigerators and, for temperatures between 2 mK and 500 mK, dilution refrigerators.
Elastocaloric refrigeration
Another potential solid-state refrigeration technique and a relatively new area of study comes from a special property of super elastic materials. These materials undergo a temperature change when experiencing an applied mechanical stress (called the elastocaloric effect). Since super elastic materials deform reversibly at high strains, the material experiences a flattened elastic region in its stress-strain curve caused by a resulting phase transformation from an austenitic to a martensitic crystal phase.
When a super elastic material experiences a stress in the austenitic phase, it undergoes an exothermic phase transformation to the martensitic phase, which causes the material to heat up. Removing the stress reverses the process, restores the material to its austenitic phase, and absorbs heat from the surroundings cooling down the material. | Refrigeration | Wikipedia | 469 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
The most appealing part of this research is how potentially energy efficient and environmentally friendly this cooling technology is. The different materials used, commonly shape-memory alloys, provide a non-toxic source of emission free refrigeration. The most commonly studied materials studied are shape-memory alloys, like nitinol and Cu-Zn-Al. Nitinol is of the more promising alloys with output heat at about 66 J/cm3 and a temperature change of about 16–20 K. Due to the difficulty in manufacturing some of the shape memory alloys, alternative materials like natural rubber have been studied. Even though rubber may not give off as much heat per volume (12 J/cm3 ) as the shape memory alloys, it still generates a comparable temperature change of about 12 K and operates at a suitable temperature range, low stresses, and low cost.
The main challenge however comes from potential energy losses in the form of hysteresis, often associated with this process. Since most of these losses comes from incompatibilities between the two phases, proper alloy tuning is necessary to reduce losses and increase reversibility and efficiency. Balancing the transformation strain of the material with the energy losses enables a large elastocaloric effect to occur and potentially a new alternative for refrigeration. | Refrigeration | Wikipedia | 261 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
Fridge Gate
The Fridge Gate method is a theoretical application of using a single logic gate to drive a refrigerator in the most energy efficient way possible without violating the laws of thermodynamics. It operates on the fact that there are two energy states in which a particle can exist: the ground state and the excited state. The excited state carries a little more energy than the ground state, small enough so that the transition occurs with high probability. There are three components or particle types associated with the fridge gate. The first is on the interior of the refrigerator, the second on the outside and the third is connected to a power supply which heats up every so often that it can reach the E state and replenish the source. In the cooling step on the inside of the refrigerator, the g state particle absorbs energy from ambient particles, cooling them, and itself jumping to the e state. In the second step, on the outside of the refrigerator where the particles are also at an e state, the particle falls to the g state, releasing energy and heating the outside particles. In the third and final step, the power supply moves a particle at the e state, and when it falls to the g state it induces an energy-neutral swap where the interior e particle is replaced by a new g particle, restarting the cycle.
Passive systems
When combining a passive daytime radiative cooling system with thermal insulation and evaporative cooling, one study found a 300% increase in ambient cooling power when compared to a stand-alone radiative cooling surface, which could extend the shelf life of food by 40% in humid climates and 200% in desert climates without refrigeration. The system's evaporative cooling layer would require water "re-charges" every 10 days to a month in humid areas and every 4 days in hot and dry areas.
Capacity ratings
The refrigeration capacity of a refrigeration system is the product of the evaporators' enthalpy rise and the evaporators' mass flow rate. The measured capacity of refrigeration is often dimensioned in the unit of kW or BTU/h. Domestic and commercial refrigerators may be rated in kJ/s, or Btu/h of cooling. For commercial and industrial refrigeration systems, the kilowatt (kW) is the basic unit of refrigeration, except in North America, where both ton of refrigeration and BTU/h are used. | Refrigeration | Wikipedia | 505 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
A refrigeration system's coefficient of performance (CoP) is very important in determining a system's overall efficiency. It is defined as refrigeration capacity in kW divided by the energy input in kW. While CoP is a very simple measure of performance, it is typically not used for industrial refrigeration in North America. Owners and manufacturers of these systems typically use performance factor (PF). A system's PF is defined as a system's energy input in horsepower divided by its refrigeration capacity in TR. Both CoP and PF can be applied to either the entire system or to system components. For example, an individual compressor can be rated by comparing the energy needed to run the compressor versus the expected refrigeration capacity based on inlet volume flow rate. It is important to note that both CoP and PF for a refrigeration system are only defined at specific operating conditions, including temperatures and thermal loads. Moving away from the specified operating conditions can dramatically change a system's performance.
Air conditioning systems used in residential application typically use SEER (Seasonal Energy Efficiency Ratio)for the energy performance rating. Air conditioning systems for commercial application often use EER (Energy Efficiency Ratio) and IEER (Integrated Energy Efficiency Ratio) for the energy efficiency performance rating. | Refrigeration | Wikipedia | 266 | 46238 | https://en.wikipedia.org/wiki/Refrigeration | Technology | Food and health | null |
Fever or pyrexia in humans is a symptom of an anti-infection defense mechanism that appears with body temperature exceeding the normal range due to an increase in the body's temperature set point in the hypothalamus. There is no single agreed-upon upper limit for normal temperature: sources use values ranging between in humans.
The increase in set point triggers increased muscle contractions and causes a feeling of cold or chills. This results in greater heat production and efforts to conserve heat. When the set point temperature returns to normal, a person feels hot, becomes flushed, and may begin to sweat. Rarely a fever may trigger a febrile seizure, with this being more common in young children. Fevers do not typically go higher than .
A fever can be caused by many medical conditions ranging from non-serious to life-threatening. This includes viral, bacterial, and parasitic infections—such as influenza, the common cold, meningitis, urinary tract infections, appendicitis, Lassa fever, COVID-19, and malaria. Non-infectious causes include vasculitis, deep vein thrombosis, connective tissue disease, side effects of medication or vaccination, and cancer. It differs from hyperthermia, in that hyperthermia is an increase in body temperature over the temperature set point, due to either too much heat production or not enough heat loss.
Treatment to reduce fever is generally not required. Treatment of associated pain and inflammation, however, may be useful and help a person rest. Medications such as ibuprofen or paracetamol (acetaminophen) may help with this as well as lower temperature. Children younger than three months require medical attention, as might people with serious medical problems such as a compromised immune system or people with other symptoms. Hyperthermia requires treatment.
Fever is one of the most common medical signs. It is part of about 30% of healthcare visits by children and occurs in up to 75% of adults who are seriously sick. While fever evolved as a defense mechanism, treating a fever does not appear to improve or worsen outcomes. Fever is often viewed with greater concern by parents and healthcare professionals than is usually deserved, a phenomenon known as "fever phobia." | Fever | Wikipedia | 463 | 46253 | https://en.wikipedia.org/wiki/Fever | Biology and health sciences | Symptoms and signs | Health |
Associated symptoms
A fever is usually accompanied by sickness behavior, which consists of lethargy, depression, loss of appetite, sleepiness, hyperalgesia, dehydration, and the inability to concentrate. Sleeping with a fever can often cause intense or confusing nightmares, commonly called "fever dreams". Mild to severe delirium (which can also cause hallucinations) may also present itself during high fevers.
Diagnosis
A range for normal temperatures has been found. Central temperatures, such as rectal temperatures, are more accurate than peripheral temperatures.
Fever is generally agreed to be present if the elevated temperature is caused by a raised set point and:
Temperature in the anus (rectum/rectal) is at or over . An ear (tympanic) or forehead (temporal) temperature may also be used.
Temperature in the mouth (oral) is at or over in the morning or over in the afternoon
Temperature under the arm (axillary) is usually about below core body temperature.
In adults, the normal range of oral temperatures in healthy individuals is among men and among women, while when taken rectally it is among men and among women, and for ear measurement it is among men and among women.
Normal body temperatures vary depending on many factors, including age, sex, time of day, ambient temperature, activity level, and more. Normal daily temperature variation has been described as 0.5 °C (0.9 °F). A raised temperature is not always a fever. For example, the temperature rises in healthy people when they exercise, but this is not considered a fever, as the set point is normal. On the other hand, a "normal" temperature may be a fever, if it is unusually high for that person; for example, medically frail elderly people have a decreased ability to generate body heat, so a "normal" temperature of may represent a clinically significant fever.
Hyperthermia
Hyperthermia is an elevation of body temperature over the temperature set point, due to either too much heat production or not enough heat loss. Hyperthermia is thus not considered fever. Hyperthermia should not be confused with hyperpyrexia (which is a very high fever).
Clinically, it is important to distinguish between fever and hyperthermia as hyperthermia may quickly lead to death and does not respond to antipyretic medications. The distinction may however be difficult to make in an emergency setting, and is often established by identifying possible causes. | Fever | Wikipedia | 505 | 46253 | https://en.wikipedia.org/wiki/Fever | Biology and health sciences | Symptoms and signs | Health |
Types
Various patterns of measured patient temperatures have been observed, some of which may be indicative of a particular medical diagnosis:
Continuous fever, where temperature remains above normal and does not fluctuate more than in 24 hours (e.g. in bacterial pneumonia, typhoid fever, infective endocarditis, tuberculosis, or typhus).
Intermittent fever is present only for a certain period, later cycling back to normal (e.g., in malaria, leishmaniasis, pyemia, sepsis, or African trypanosomiasis).
Remittent fever, where the temperature remains above normal throughout the day and fluctuates more than in 24 hours (e.g., in infective endocarditis or brucellosis).
Pel–Ebstein fever is a cyclic fever that is rarely seen in patients with Hodgkin's lymphoma.
Undulant fever, seen in brucellosis.
Typhoid fever is a continuous fever showing a characteristic step-ladder pattern, a step-wise increase in temperature with a high plateau.
Among the types of intermittent fever are ones specific to cases of malaria caused by different pathogens. These are:
Quotidian fever, with a 24-hour periodicity, typical of malaria caused by Plasmodium knowlesi (P. knowlesi);
Tertian fever, with a 48-hour periodicity, typical of later course malaria caused by P. falciparum, P. vivax, or P. ovale;
Quartan fever, with a 72-hour periodicity, typical of later course malaria caused by P. malariae.
In addition, there is disagreement regarding whether a specific fever pattern is associated with Hodgkin's lymphoma—the Pel–Ebstein fever, with patients argued to present high temperature for one week, followed by low for the next week, and so on, where the generality of this pattern is debated. | Fever | Wikipedia | 413 | 46253 | https://en.wikipedia.org/wiki/Fever | Biology and health sciences | Symptoms and signs | Health |
Persistent fever that cannot be explained after repeated routine clinical inquiries is called fever of unknown origin. A neutropenic fever, also called febrile neutropenia, is a fever in the absence of normal immune system function. Because of the lack of infection-fighting neutrophils, a bacterial infection can spread rapidly; this fever is, therefore, usually considered to require urgent medical attention. This kind of fever is more commonly seen in people receiving immune-suppressing chemotherapy than in apparently healthy people.
Hyperpyrexia
Hyperpyrexia is an extreme elevation of body temperature which, depending upon the source, is classified as a core body temperature greater than or equal to ; the range of hyperpyrexia includes cases considered severe (≥ 40 °C) and extreme (≥ 42 °C). It differs from hyperthermia in that one's thermoregulatory system's set point for body temperature is set above normal, then heat is generated to achieve it. In contrast, hyperthermia involves body temperature rising above its set point due to outside factors. The high temperatures of hyperpyrexia are considered medical emergencies, as they may indicate a serious underlying condition or lead to severe morbidity (including permanent brain damage), or to death. A common cause of hyperpyrexia is an intracranial hemorrhage. Other causes in emergency room settings include sepsis, Kawasaki syndrome, neuroleptic malignant syndrome, drug overdose, serotonin syndrome, and thyroid storm.
Differential diagnosis
Fever is a common symptom of many medical conditions: | Fever | Wikipedia | 324 | 46253 | https://en.wikipedia.org/wiki/Fever | Biology and health sciences | Symptoms and signs | Health |
Infectious disease, e.g., COVID-19, dengue, Ebola, gastroenteritis, HIV, influenza, Lyme disease, rocky mountain spotted fever, secondary syphilis, malaria, mononucleosis, as well as infections of the skin, e.g., abscesses and boils.
Immunological diseases, e.g., relapsing polychondritis, autoimmune hepatitis, granulomatosis with polyangiitis, Horton disease, inflammatory bowel diseases, Kawasaki disease, lupus erythematosus, sarcoidosis, Still's disease, rheumatoid arthritis, lymphoproliferative disorders and psoriasis;
Tissue destruction, as a result of cerebral bleeding, crush syndrome, hemolysis, infarction, rhabdomyolysis, surgery, etc.;
Cancers, particularly blood cancers such as leukemia and lymphomas;
Metabolic disorders, e.g., gout, and porphyria; and
Inherited metabolic disorder, e.g., Fabry disease.
Adult and pediatric manifestations for the same disease may differ; for instance, in COVID-19, one metastudy describes 92.8% of adults versus 43.9% of children presenting with fever.
In addition, fever can result from a reaction to an incompatible blood product.
Function
Immune function
Fever is thought to contribute to host defense, as the reproduction of pathogens with strict temperature requirements can be hindered, and the rates of some important immunological reactions are increased by temperature. Fever has been described in teaching texts as assisting the healing process in various ways, including:
increased mobility of leukocytes;
enhanced leukocyte phagocytosis;
decreased endotoxin effects; and
increased proliferation of T cells.
Advantages and disadvantages
A fever response to an infectious disease is generally regarded as protective, whereas fever in non-infections may be maladaptive. Studies have not been consistent on whether treating fever generally worsens or improves mortality risk. Benefits or harms may depend on the type of infection, health status of the patient and other factors. Studies using warm-blooded vertebrates suggest that they recover more rapidly from infections or critical illness due to fever. In sepsis, fever is associated with reduced mortality.
Pathophysiology of fever induction | Fever | Wikipedia | 487 | 46253 | https://en.wikipedia.org/wiki/Fever | Biology and health sciences | Symptoms and signs | Health |
Hypothalamus
Temperature is regulated in the hypothalamus. The trigger of a fever, called a pyrogen, results in the release of prostaglandin E2 (PGE2). PGE2 in turn acts on the hypothalamus, which creates a systemic response in the body, causing heat-generating effects to match a new higher temperature set point. There are four receptors in which PGE2 can bind (EP1-4), with a previous study showing the EP3 subtype is what mediates the fever response. Hence, the hypothalamus can be seen as working like a thermostat. When the set point is raised, the body increases its temperature through both active generation of heat and retention of heat. Peripheral vasoconstriction both reduces heat loss through the skin and causes the person to feel cold. Norepinephrine increases thermogenesis in brown adipose tissue, and muscle contraction through shivering raises the metabolic rate.
If these measures are insufficient to make the blood temperature in the brain match the new set point in the hypothalamus, the brain orchestrates heat effector mechanisms via the autonomic nervous system or primary motor center for shivering. These may be:
Increased heat production by increased muscle tone, shivering (muscle movements to produce heat) and release of hormones like epinephrine; and
Prevention of heat loss, e.g., through vasoconstriction.
When the hypothalamic set point moves back to baseline—either spontaneously or via medication—normal functions such as sweating, and the reverse of the foregoing processes (e.g., vasodilation, end of shivering, and nonshivering heat production) are used to cool the body to the new, lower setting.
This contrasts with hyperthermia, in which the normal setting remains, and the body overheats through undesirable retention of excess heat or over-production of heat. Hyperthermia is usually the result of an excessively hot environment (heat stroke) or an adverse reaction to drugs. Fever can be differentiated from hyperthermia by the circumstances surrounding it and its response to anti-pyretic medications.
In infants, the autonomic nervous system may also activate brown adipose tissue to produce heat (non-shivering thermogenesis).
Increased heart rate and vasoconstriction contribute to increased blood pressure in fever.
Pyrogens | Fever | Wikipedia | 512 | 46253 | https://en.wikipedia.org/wiki/Fever | Biology and health sciences | Symptoms and signs | Health |
A pyrogen is a substance that induces fever. In the presence of an infectious agent, such as bacteria, viruses, viroids, etc., the immune response of the body is to inhibit their growth and eliminate them. The most common pyrogens are endotoxins, which are lipopolysaccharides (LPS) produced by Gram-negative bacteria such as E. coli. But pyrogens include non-endotoxic substances (derived from microorganisms other than gram-negative-bacteria or from chemical substances) as well. The types of pyrogens include internal (endogenous) and external (exogenous) to the body.
The "pyrogenicity" of given pyrogens varies: in extreme cases, bacterial pyrogens can act as superantigens and cause rapid and dangerous fevers.
Endogenous
Endogenous pyrogens are cytokines released from monocytes (which are part of the immune system). In general, they stimulate chemical responses, often in the presence of an antigen, leading to a fever. Whilst they can be a product of external factors like exogenous pyrogens, they can also be induced by internal factors like damage associated molecular patterns such as cases like rheumatoid arthritis or lupus.
Major endogenous pyrogens are interleukin 1 (α and β) and interleukin 6 (IL-6). Minor endogenous pyrogens include interleukin-8, tumor necrosis factor-β, macrophage inflammatory protein-α and macrophage inflammatory protein-β as well as interferon-α, interferon-β, and interferon-γ. Tumor necrosis factor-α (TNF) also acts as a pyrogen, mediated by interleukin 1 (IL-1) release. These cytokine factors are released into general circulation, where they migrate to the brain's circumventricular organs where they are more easily absorbed than in areas protected by the blood–brain barrier. The cytokines then bind to endothelial receptors on vessel walls to receptors on microglial cells, resulting in activation of the arachidonic acid pathway. | Fever | Wikipedia | 479 | 46253 | https://en.wikipedia.org/wiki/Fever | Biology and health sciences | Symptoms and signs | Health |
Of these, IL-1β, TNF, and IL-6 are able to raise the temperature setpoint of an organism and cause fever. These proteins produce a cyclooxygenase which induces the hypothalamic production of PGE2 which then stimulates the release of neurotransmitters such as cyclic adenosine monophosphate and increases body temperature.
Exogenous
Exogenous pyrogens are external to the body and are of microbial origin. In general, these pyrogens, including bacterial cell wall products, may act on Toll-like receptors in the hypothalamus and elevate the thermoregulatory setpoint.
An example of a class of exogenous pyrogens are bacterial lipopolysaccharides (LPS) present in the cell wall of gram-negative bacteria. According to one mechanism of pyrogen action, an immune system protein, lipopolysaccharide-binding protein (LBP), binds to LPS, and the LBP–LPS complex then binds to a CD14 receptor on a macrophage. The LBP-LPS binding to CD14 results in cellular synthesis and release of various endogenous cytokines, e.g., interleukin 1 (IL-1), interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNFα). A further downstream event is activation of the arachidonic acid pathway.
PGE2 release
PGE2 release comes from the arachidonic acid pathway. This pathway (as it relates to fever), is mediated by the enzymes phospholipase A2 (PLA2), cyclooxygenase-2 (COX-2), and prostaglandin E2 synthase. These enzymes ultimately mediate the synthesis and release of PGE2. | Fever | Wikipedia | 403 | 46253 | https://en.wikipedia.org/wiki/Fever | Biology and health sciences | Symptoms and signs | Health |
PGE2 is the ultimate mediator of the febrile response. The setpoint temperature of the body will remain elevated until PGE2 is no longer present. PGE2 acts on neurons in the preoptic area (POA) through the prostaglandin E receptor 3 (EP3). EP3-expressing neurons in the POA innervate the dorsomedial hypothalamus (DMH), the rostral raphe pallidus nucleus in the medulla oblongata (rRPa), and the paraventricular nucleus (PVN) of the hypothalamus. Fever signals sent to the DMH and rRPa lead to stimulation of the sympathetic output system, which evokes non-shivering thermogenesis to produce body heat and skin vasoconstriction to decrease heat loss from the body surface. It is presumed that the innervation from the POA to the PVN mediates the neuroendocrine effects of fever through the pathway involving pituitary gland and various endocrine organs.
Management
Fever does not necessarily need to be treated, and most people with a fever recover without specific medical attention. Although it is unpleasant, fever rarely rises to a dangerous level even if untreated. Damage to the brain generally does not occur until temperatures reach , and it is rare for an untreated fever to exceed . Treating fever in people with sepsis does not affect outcomes. Small trials have shown no benefit of treating fevers of or higher of critically ill patients in ICUs, and one trial was terminated early because patients receiving aggressive fever treatment were dying more often.
According to the NIH, the two assumptions which are generally used to argue in favor of treating fevers have not been experimentally validated. These are that (1) a fever is noxious, and (2) suppression of a fever will reduce its noxious effect. Most of the other studies supporting the association of fever with poorer outcomes have been observational in nature. In theory, these critically ill patients and those faced with additional physiologic stress may benefit from fever reduction, but the evidence on both sides of the argument appears to be mostly equivocal. | Fever | Wikipedia | 459 | 46253 | https://en.wikipedia.org/wiki/Fever | Biology and health sciences | Symptoms and signs | Health |
Conservative measures
Limited evidence supports sponging or bathing feverish children with tepid water. The use of a fan or air conditioning may somewhat reduce the temperature and increase comfort. If the temperature reaches the extremely high level of hyperpyrexia, aggressive cooling is required (generally produced mechanically via conduction by applying numerous ice packs across most of the body or direct submersion in ice water). In general, people are advised to keep adequately hydrated. Whether increased fluid intake improves symptoms or shortens respiratory illnesses such as the common cold is not known.
Medications
Medications that lower fevers are called antipyretics. The antipyretic ibuprofen is effective in reducing fevers in children. It is more effective than acetaminophen (paracetamol) in children. Ibuprofen and acetaminophen may be safely used together in children with fevers. The efficacy of acetaminophen by itself in children with fevers has been questioned. Ibuprofen is also superior to aspirin in children with fevers. Additionally, aspirin is not recommended in children and young adults (those under the age of 16 or 19 depending on the country) due to the risk of Reye's syndrome.
Using both paracetamol and ibuprofen at the same time or alternating between the two is more effective at decreasing fever than using only paracetamol or ibuprofen. It is not clear if it increases child comfort. Response or nonresponse to medications does not predict whether or not a child has a serious illness.
With respect to the effect of antipyretics on the risk of death in those with infection, studies have found mixed results, as of 2019.
Epidemiology
Fever is one of the most common medical signs. It is part of about 30% of healthcare visits by children, and occurs in up to 75% of adults who are seriously sick. About 5% of people who go to an emergency room have a fever.
History
A number of types of fever were known as early as 460 BC to 370 BC when Hippocrates was practicing medicine including that due to malaria (tertian or every 2 days and quartan or every 3 days). It also became clear around this time that fever was a symptom of disease rather than a disease in and of itself. | Fever | Wikipedia | 485 | 46253 | https://en.wikipedia.org/wiki/Fever | Biology and health sciences | Symptoms and signs | Health |
Infections presenting with fever were a major source of mortality in humans for about 200,000 years. Until the late nineteenth century, approximately half of all humans died from infections before the age of fifteen.
An older term, febricula (a diminutive form of the Latin word for fever), was once used to refer to a low-grade fever lasting only a few days. This term fell out of use in the early 20th century, and the symptoms it referred to are now thought to have been caused mainly by various minor viral respiratory infections.
Society and culture
Mythology
Febris (fever in Latin) is the goddess of fever in Roman mythology. People with fevers would visit her temples.
Tertiana and Quartana are the goddesses of tertian and quartan fevers of malaria in Roman mythology.
Jvarasura (fever-demon in Hindi) is the personification of fever and disease in Hindu and Buddhist mythology.
Pediatrics
Fever is often viewed with greater concern by parents and healthcare professionals than might be deserved, a phenomenon known as fever phobia, which is based in both caregiver's and parents' misconceptions about fever in children. Among them, many parents incorrectly believe that fever is a disease rather than a medical sign, that even low fevers are harmful, and that any temperature even briefly or slightly above the oversimplified "normal" number marked on a thermometer is a clinically significant fever. They are also afraid of harmless side effects like febrile seizures and dramatically overestimate the likelihood of permanent damage from typical fevers. The underlying problem, according to professor of pediatrics Barton D. Schmitt, is that "as parents we tend to suspect that our children's brains may melt." As a result of these misconceptions parents are anxious, give the child fever-reducing medicine when the temperature is technically normal or only slightly elevated, and interfere with the child's sleep to give the child more medicine.
Other species | Fever | Wikipedia | 409 | 46253 | https://en.wikipedia.org/wiki/Fever | Biology and health sciences | Symptoms and signs | Health |
Fever is an important metric for the diagnosis of disease in domestic animals. The body temperature of animals, which is taken rectally, is different from one species to another. For example, a horse is said to have a fever above (). In species that allow the body to have a wide range of "normal" temperatures, such as camels, whose body temperature varies as the environmental temperature varies, the body temperature which constitutes a febrile state differs depending on the environmental temperature. Fever can also be behaviorally induced by invertebrates that do not have immune-system based fever. For instance, some species of grasshopper will thermoregulate to achieve body temperatures that are 2–5 °C higher than normal in order to inhibit the growth of fungal pathogens such as Beauveria bassiana and Metarhizium acridum. Honeybee colonies are also able to induce a fever in response to a fungal parasite Ascosphaera apis. | Fever | Wikipedia | 194 | 46253 | https://en.wikipedia.org/wiki/Fever | Biology and health sciences | Symptoms and signs | Health |
Telemetry is the in situ collection of measurements or other data at remote points and their automatic transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Greek roots tele, 'far off', and metron, 'measure'. Systems that need external instructions and data to operate require the counterpart of telemetry: telecommand.
Although the term commonly refers to wireless data transfer mechanisms (e.g., using radio, ultrasonic, or infrared systems), it also encompasses data transferred over other media such as a telephone or computer network, optical link or other wired communications like power line carriers. Many modern telemetry systems take advantage of the low cost and ubiquity of GSM networks by using SMS to receive and transmit telemetry data.
A telemeter is a physical device used in telemetry. It consists of a sensor, a transmission path, and a display, recording, or control device. Electronic devices are widely used in telemetry and can be wireless or hard-wired, analog or digital. Other technologies are also possible, such as mechanical, hydraulic and optical.
Telemetry may be commutated to allow the transmission of multiple data streams in a fixed frame.
History
The beginning of industrial telemetry lies in the steam age, although the sensor was not called telemeter at that time. Examples are James Watt's (1736-1819) additions to his steam engines for monitoring from a (near) distance such as the mercury pressure gauge and the fly-ball governor.
Although the original telemeter referred to a ranging device (the rangefinding telemeter), by the late 19th century the same term had been in wide use by electrical engineers applying it refer to electrically operated devices measuring many other quantities besides distance (for instance, in the patent of an "Electric Telemeter Transmitter"). General telemeters included such sensors as the thermocouple (from the work of Thomas Johann Seebeck), the resistance thermometer (by William Siemens based on the work of Humphry Davy), and the electrical strain gauge (based on Lord Kelvin's discovery that conductors under mechanical strain change their resistance) and output devices such as Samuel Morse's telegraph sounder and the relay. In 1889 this led an author in the Institution of Civil Engineers proceedings to suggest that the term for the rangefinder telemeter might be replaced with tacheometer. | Telemetry | Wikipedia | 500 | 46256 | https://en.wikipedia.org/wiki/Telemetry | Physical sciences | Basics | Basics and measurement |
In the 1930s use of electrical telemeters grew rapidly. The electrical strain gauge was widely used in rocket and aviation research and the radiosonde was invented for meteorological measurements. The advent of World War II gave an impetus to industrial development and henceforth many of these telemeters became commercially viable.
Carrying on from rocket research, radio telemetry was used routinely as space exploration got underway. Spacecraft are in a place where a physical connection is not possible, leaving radio or other electromagnetic waves (such as infrared lasers) as the only viable option for telemetry. During crewed space missions it is used to monitor not only parameters of the vehicle, but also the health and life support of the astronauts. During the Cold War telemetry found uses in espionage. US intelligence found that they could monitor the telemetry from Soviet missile tests by building a telemeter of their own to intercept the radio signals and hence learn a great deal about Soviet capabilities.
Types of telemeter
Telemeters are the physical devices used in telemetry. It consists of a sensor, a transmission path, and a display, recording, or control device. Electronic devices are widely used in telemetry and can be wireless or hard-wired, analog or digital. Other technologies are also possible, such as mechanical, hydraulic and optical.
Telemetering information over wire had its origins in the 19th century. One of the first data-transmission circuits was developed in 1845 between the Russian Tsar's Winter Palace and army headquarters. In 1874, French engineers built a system of weather and snow-depth sensors on Mont Blanc that transmitted real-time information to Paris. In 1901 the American inventor C. Michalke patented the selsyn, a circuit for sending synchronized rotation information over a distance. In 1906 a set of seismic stations were built with telemetering to the Pulkovo Observatory in Russia. In 1912, Commonwealth Edison developed a system of telemetry to monitor electrical loads on its power grid. The Panama Canal (completed 1913–1914) used extensive telemetry systems to monitor locks and water levels. | Telemetry | Wikipedia | 424 | 46256 | https://en.wikipedia.org/wiki/Telemetry | Physical sciences | Basics | Basics and measurement |
Wireless telemetry made early appearances in the radiosonde, developed concurrently in 1930 by Robert Bureau in France and Pavel Molchanov in Russia. Molchanov's system modulated temperature and pressure measurements by converting them to wireless Morse code. The German V-2 rocket used a system of primitive multiplexed radio signals called "Messina" to report four rocket parameters, but it was so unreliable that Wernher von Braun once claimed it was more useful to watch the rocket through binoculars.
In the US and the USSR, the Messina system was quickly replaced with better systems; in both cases, based on pulse-position modulation (PPM).
Early Soviet missile and space telemetry systems which were developed in the late 1940s used either PPM (e.g., the Tral telemetry system developed by OKB-MEI) or pulse-duration modulation (e.g., the RTS-5 system developed by NII-885). In the United States, early work employed similar systems, but were later replaced by pulse-code modulation (PCM) (for example, in the Mars probe Mariner 4). Later Soviet interplanetary probes used redundant radio systems, transmitting telemetry by PCM on a decimeter band and PPM on a centimeter band.
Applications
Meteorology
Weather balloons use telemetry to transmit meteorological data since 1920.
Oil and gas industry
Telemetry is used to transmit drilling mechanics and formation evaluation information uphole, in real time, as a well is drilled. These services are known as Measurement while drilling and Logging while drilling. Information acquired thousands of feet below ground, while drilling, is sent through the drilling hole to the surface sensors and the demodulation software. The pressure wave (sana) is translated into useful information after DSP and noise filters. This information is used for Formation evaluation, Drilling Optimization, and Geosteering. | Telemetry | Wikipedia | 389 | 46256 | https://en.wikipedia.org/wiki/Telemetry | Physical sciences | Basics | Basics and measurement |
Motor racing
Telemetry is a key factor in modern motor racing, allowing race engineers to interpret data collected during a test or race and use it to properly tune the car for optimum performance. Systems used in series such as Formula One have become advanced to the point where the potential lap time of the car can be calculated, and this time is what the driver is expected to meet. Examples of measurements on a race car include accelerations (G forces) in three axes, temperature readings, wheel speed, and suspension displacement. In Formula One, driver input is also recorded so the team can assess driver performance and (in case of an accident) the FIA can determine or rule out driver error as a possible cause.
Later developments include two-way telemetry which allows engineers to update calibrations on the car in real time (even while it is out on the track). In Formula One, two-way telemetry surfaced in the early 1990s and consisted of a message display on the dashboard which the team could update. Its development continued until May 2001, when it was first allowed on the cars. By 2002, teams were able to change engine mapping and deactivate engine sensors from the pit while the car was on the track. For the 2003 season, the FIA banned two-way telemetry from Formula One; however, the technology may be used in other types of racing or on road cars.
One way telemetry system has also been applied in R/C racing car to get information by car's sensors like: engine RPM, voltage, temperatures, throttle.
Transportation
In the transportation industry, telemetry provides meaningful information about a vehicle or driver's performance by collecting data from sensors within the vehicle. This is undertaken for various reasons ranging from staff compliance monitoring, insurance rating to predictive maintenance.
Telemetry is used to link traffic counter devices to data recorders to measure traffic flows and vehicle lengths and weights. | Telemetry | Wikipedia | 392 | 46256 | https://en.wikipedia.org/wiki/Telemetry | Physical sciences | Basics | Basics and measurement |
Telemetry is used by the railway industry for measuring the health of trackage. This permits optimized and focused predictive and preventative maintenance. Typically this is done with specialized trains, such as the New Measurement Train used in the United Kingdom by Network Rail, which can check for track defects, such as problems with gauge, and deformations in the rail. Japan uses similar, but quicker trains, nicknamed Doctor Yellow. Such trains, besides checking the tracks, can also verify whether or not there are any problems with the overhead power supply (catenary), where it is installed. Dedicated rail inspection companies, such as Sperry Rail, have their own customized rail cars and rail-wheel equipped trucks, that use a variety of methods, including lasers, ultrasound, and induction (measuring resulting magnetic fields from running electricity into rails) to find any defects.
Agriculture
Most activities related to healthy crops and good yields depend on timely availability of weather and soil data. Therefore, wireless weather stations play a major role in disease prevention and precision irrigation. These stations transmit parameters necessary for decision-making to a base station: air temperature and relative humidity, precipitation and leaf wetness (for disease prediction models), solar radiation and wind speed (to calculate evapotranspiration), water deficit stress (WDS) leaf sensors and soil moisture (crucial to irrigation decisions).
Because local micro-climates can vary significantly, such data needs to come from within the crop. Monitoring stations usually transmit data back by terrestrial radio, although occasionally satellite systems are used. Solar power is often employed to make the station independent of the power grid.
Water management
Telemetry is important in water management, including water quality and stream gauging functions. Major applications include AMR (automatic meter reading), groundwater monitoring, leak detection in distribution pipelines and equipment surveillance. Having data available in almost real time allows quick reactions to events in the field. Telemetry control allows engineers to intervene with assets such as pumps and by remotely switching pumps on or off depending on the circumstances. Watershed telemetry is an excellent strategy of how to implement a water management system. | Telemetry | Wikipedia | 431 | 46256 | https://en.wikipedia.org/wiki/Telemetry | Physical sciences | Basics | Basics and measurement |
Defense, space and resource exploration
Telemetry is used in complex systems such as missiles, RPVs, spacecraft, oil rigs, and chemical plants since it allows the automatic monitoring, alerting, and record-keeping necessary for efficient and safe operation. Space agencies such as NASA, ISRO, the European Space Agency (ESA), and other agencies use telemetry and/or telecommand systems to collect data from spacecraft and satellites.
Telemetry is vital in the development of missiles, satellites and aircraft because the system might be destroyed during or after the test. Engineers need critical system parameters to analyze (and improve) the performance of the system. In the absence of telemetry, this data would often be unavailable.
Space science
Telemetry is used by crewed or uncrewed spacecraft for data transmission. Distances of more than 10 billion kilometres have been covered, e.g., by Voyager 1.
Rocketry
In rocketry, telemetry equipment forms an integral part of the rocket range assets used to monitor the position and health of a launch vehicle to determine range safety flight termination criteria (Range purpose is for public safety). Problems include the extreme environment (temperature, acceleration and vibration), the energy supply, antenna alignment and (at long distances, e.g., in spaceflight) signal travel time.
Flight testing
Today nearly every type of aircraft, missiles, or spacecraft carries a wireless telemetry system as it is tested. Aeronautical mobile telemetry is used for the safety of the pilots and persons on the ground during flight tests. Telemetry from an on-board flight test instrumentation system is the primary source of real-time measurement and status information transmitted during the testing of crewed and uncrewed aircraft.
Military intelligence
Intercepted telemetry was an important source of intelligence for the United States and UK when Soviet missiles were tested; for this purpose, the United States operated a listening post in Iran. Eventually, the Russians discovered the United States intelligence-gathering network and encrypted their missile-test telemetry signals. Telemetry was also a source for the Soviets, who operated listening ships in Cardigan Bay to eavesdrop on UK missile tests performed in the area. | Telemetry | Wikipedia | 452 | 46256 | https://en.wikipedia.org/wiki/Telemetry | Physical sciences | Basics | Basics and measurement |
Energy monitoring
In factories, buildings and houses, energy consumption of systems such as HVAC are monitored at multiple locations; related parameters (e.g., temperature) are sent via wireless telemetry to a central location. The information is collected and processed, enabling the most efficient use of energy. Such systems also facilitate predictive maintenance.
Resource distribution
Many resources need to be distributed over wide areas. Telemetry is useful in these cases, since it allows the logistics system to channel resources where they are needed, as well as provide security for those assets; principal examples of this are dry goods, fluids, and granular bulk solids.
Dry goods
Dry goods, such as packaged merchandise, may be tracked and remotely monitored, tracked and inventoried by RFID sensing systems, barcode reader, optical character recognition (OCR) reader, or other sensing devices—coupled to telemetry devices, to detect RFID tags, barcode labels or other identifying markers affixed to the item, its package, or (for large items and bulk shipments) affixed to its shipping container or vehicle. This facilitates knowledge of their location, and can record their status and disposition, as when merchandise with barcode labels is scanned through a checkout reader at point-of-sale systems in a retail store. Stationary or hand-held barcode RFID scanners or Optical reader with remote communications, can be used to expedite inventory tracking and counting in stores, warehouses, shipping terminals, transportation carriers and factories.
Fluids
Fluids stored in tanks are a principal object of constant commercial telemetry. This typically includes monitoring of tank farms in gasoline refineries and chemical plants—and distributed or remote tanks, which must be replenished when empty (as with gas station storage tanks, home heating oil tanks, or ag-chemical tanks at farms), or emptied when full (as with production from oil wells, accumulated waste products, and newly produced fluids). Telemetry is used to communicate the variable measurements of flow and tank level sensors detecting fluid movements and/or volumes by pneumatic, hydrostatic, or differential pressure; tank-confined ultrasonic, radar or Doppler effect echoes; or mechanical or magnetic sensors. | Telemetry | Wikipedia | 448 | 46256 | https://en.wikipedia.org/wiki/Telemetry | Physical sciences | Basics | Basics and measurement |
Bulk solids
Telemetry of bulk solids is common for tracking and reporting the volume status and condition of grain and livestock feed bins, powdered or granular food, powders and pellets for manufacturing, sand and gravel, and other granular bulk solids. While technology associated with fluid tank monitoring also applies, in part, to granular bulk solids, reporting of overall container weight, or other gross characteristics and conditions, are sometimes required, owing to bulk solids' more complex and variable physical characteristics.
Medicine/healthcare
Telemetry is used for patients (biotelemetry) who are at risk of abnormal heart activity, generally in a coronary care unit. Telemetry specialists are sometimes used to monitor many patients within a hospital. Such patients are outfitted with measuring, recording and transmitting devices. A data log can be useful in diagnosis of the patient's condition by doctors. An alerting function can alert nurses if the patient is suffering from an acute (or dangerous) condition.
Systems are available in medical-surgical nursing for monitoring to rule out a heart condition, or to monitor a response to antiarrhythmic medications such as amiodarone.
A new and emerging application for telemetry is in the field of neurophysiology, or neurotelemetry. Neurophysiology is the study of the central and peripheral nervous systems through the recording of bioelectrical activity, whether spontaneous or stimulated. In neurotelemetry (NT) the electroencephalogram (EEG) of a patient is monitored remotely by a registered EEG technologist using advanced communication software. The goal of neurotelemetry is to recognize a decline in a patient's condition before physical signs and symptoms are present.
Neurotelemetry is synonymous with real-time continuous video EEG monitoring and has application in the epilepsy monitoring unit, neuro ICU, pediatric ICU and newborn ICU. Due to the labor-intensive nature of continuous EEG monitoring NT is typically done in the larger academic teaching hospitals using in-house programs that include R.EEG Technologists, IT support staff, neurologist and neurophysiologist and monitoring support personnel.
Modern microprocessor speeds, software algorithms and video data compression allow hospitals to centrally record and monitor continuous digital EEGs of multiple critically ill patients simultaneously. | Telemetry | Wikipedia | 482 | 46256 | https://en.wikipedia.org/wiki/Telemetry | Physical sciences | Basics | Basics and measurement |
Neurotelemetry and continuous EEG monitoring provides dynamic information about brain function that permits early detection of changes in neurologic status, which is especially useful when the clinical examination is limited.
Fishery and wildlife research and management
Telemetry is used to study wildlife, and has been useful for monitoring threatened species at the individual level. Animals under study can be outfitted with instrumentation tags, which include sensors that measure temperature, diving depth and duration (for marine animals), speed and location (using GPS or Argos packages). Telemetry tags can give researchers information about animal behavior, functions, and their environment. This information is then either stored (with archival tags) or the tags can send (or transmit) their information to a satellite or handheld receiving device. Capturing and marking wild animals can put them at some risk, so it is important to minimize these impacts.
Retail
At a 2005 workshop in Las Vegas, a seminar noted the introduction of telemetry equipment which would allow vending machines to communicate sales and inventory data to a route truck or to a headquarters. This data could be used for a variety of purposes, such as eliminating the need for drivers to make a first trip to see which items needed to be restocked before delivering the inventory.
Retailers also use RFID tags to track inventory and prevent shoplifting. Most of these tags passively respond to RFID readers (e.g., at the cashier), but active RFID tags are available which periodically transmit location information to a base station.
Law enforcement
Telemetry hardware is useful for tracking persons and property in law enforcement. An ankle collar worn by convicts on probation can warn authorities if a person violates the terms of his or her parole, such as by straying from authorized boundaries or visiting an unauthorized location. Telemetry has also enabled bait cars, where law enforcement can rig a car with cameras and tracking equipment and leave it somewhere they expect it to be stolen. When stolen the telemetry equipment reports the location of the vehicle, enabling law enforcement to deactivate the engine and lock the doors when it is stopped by responding officers. | Telemetry | Wikipedia | 430 | 46256 | https://en.wikipedia.org/wiki/Telemetry | Physical sciences | Basics | Basics and measurement |
Energy providers
In some countries, telemetry is used to measure the amount of electrical energy consumed. The electricity meter communicates with a concentrator, and the latter sends the information through GPRS or GSM to the energy provider's server. Telemetry is also used for the remote monitoring of substations and their equipment. For data transmission, phase line carrier systems operating on frequencies between 30 and 400 kHz are sometimes used.
Falconry
In falconry, "telemetry" means a small radio transmitter carried by a bird of prey that will allow the bird's owner to track it when it is out of sight.
Testing
Telemetry is used in testing hostile environments which are dangerous to humans. Examples include munitions storage facilities, radioactive sites, volcanoes, deep sea, and outer space.
Communications
Telemetry is used in many battery operated wireless systems to inform monitoring personnel when the battery power is reaching a low point and the end item needs fresh batteries.
Mining
In the mining industry, telemetry serves two main purposes: the measurement of key parameters from mining equipment and the monitoring of safety practices. The information provided by the collection and analysis of key parameters allows for root-cause identification of inefficient operations, unsafe practices and incorrect equipment usage for maximizing productivity and safety. Further applications of the technology allow for sharing knowledge and best practices across the organization.
Software
In software, telemetry is used to gather data on the use and performance of applications and application components, e.g. how often certain features are used, measurements of start-up time and processing time, hardware, application crashes, and general usage statistics and/or user behavior. In some cases, very detailed data is reported like individual window metrics, counts of used features, and individual function timings.
This kind of telemetry can be essential to software developers to receive data from a wide variety of endpoints that can't possibly all be tested in-house, as well as getting data on the popularity of certain features and whether they should be given priority or be considered for removal. Due to concerns about privacy since software telemetry can easily be used to profile users, telemetry in user software is often user choice, commonly presented as an opt-out feature (requiring explicit user action to disable it) or user choice during the software installation process. | Telemetry | Wikipedia | 478 | 46256 | https://en.wikipedia.org/wiki/Telemetry | Physical sciences | Basics | Basics and measurement |
International standards
As in other telecommunications fields, international standards exist for telemetry equipment and software. International standards producing bodies include Consultative Committee for Space Data Systems (CCSDS) for space agencies, Inter-Range Instrumentation Group (IRIG) for missile ranges, and Telemetering Standards Coordination Committee (TSCC), an organisation of the International Foundation for Telemetering. | Telemetry | Wikipedia | 75 | 46256 | https://en.wikipedia.org/wiki/Telemetry | Physical sciences | Basics | Basics and measurement |
Lobsters are malacostracans of the family Nephropidae or its synonym Homaridae. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs have claws, including the first pair, which are usually much larger than the others. Highly prized as seafood, lobsters are economically important and are often one of the most profitable commodities in the coastal areas they populate.
Commercially important species include two species of Homarus from the northern Atlantic Ocean and scampi (which look more like a shrimp, or a "mini lobster")—the Northern Hemisphere genus Nephrops and the Southern Hemisphere genus Metanephrops.
Distinction
Although several other groups of crustaceans have the word "lobster" in their names, the unqualified term "lobster" generally refers to the clawed lobsters of the family Nephropidae. Clawed lobsters are not closely related to spiny lobsters or slipper lobsters, which have no claws (chelae), or to squat lobsters. The most similar living relatives of clawed lobsters are the reef lobsters and the three families of freshwater crayfish.
Description
Body
Lobsters are invertebrates with a hard protective exoskeleton. Like most arthropods, lobsters must shed to grow, which leaves them vulnerable. During the shedding process, several species change color. Lobsters have eight walking legs; the front three pairs bear claws, the first of which are larger than the others. The front pincers are also biologically considered legs, so they belong in the order Decapods ("ten-footed"). Although lobsters are largely bilaterally symmetrical like most other arthropods, some genera possess unequal, specialized claws. | Lobster | Wikipedia | 370 | 46310 | https://en.wikipedia.org/wiki/Lobster | Biology and health sciences | Crustaceans | null |
Lobster anatomy includes two main body parts: the cephalothorax and the abdomen. The cephalothorax fuses the head and the thorax, both of which are covered by a chitinous carapace. The lobster's head bears antennae, antennules, mandibles, the first and second maxillae. The head also bears the (usually stalked) compound eyes. Because lobsters live in murky environments at the bottom of the ocean, they mostly use their antennae as sensors. The lobster eye has a reflective structure above a convex retina. In contrast, most complex eyes use refractive ray concentrators (lenses) and a concave retina. The lobster's thorax is composed of maxillipeds, appendages that function primarily as mouthparts, and pereiopods, appendages that serve for walking and for gathering food. The abdomen includes pleopods (also known as swimmerets), used for swimming, as well as the tail fan, composed of uropods and the telson.
Lobsters, like snails and spiders, have blue blood due to the presence of hemocyanin, which contains copper. In contrast, vertebrates, and many other animals have red blood from iron-rich hemoglobin. Lobsters possess a green hepatopancreas, called the tomalley by chefs, which functions as the animal's liver and pancreas.
Lobsters of the family Nephropidae are similar in overall form to several other related groups. They differ from freshwater crayfish in lacking the joint between the last two segments of the thorax, and they differ from the reef lobsters of the family Enoplometopidae in having full claws on the first three pairs of legs, rather than just one. The distinctions from fossil families such as the Chilenophoberidae are based on the pattern of grooves on the carapace.
Analysis of the neural gene complement revealed extraordinary development of the chemosensory machinery, including a profound diversification of ligand-gated ion channels and secretory molecules. | Lobster | Wikipedia | 435 | 46310 | https://en.wikipedia.org/wiki/Lobster | Biology and health sciences | Crustaceans | null |
Coloring
Typically, lobsters are dark colored, either bluish-green or greenish-brown, to blend in with the ocean floor, but they can be found in many colors. Lobsters with atypical coloring are extremely rare, accounting for only a few of the millions caught every year, and due to their rarity, they usually are not eaten, instead being released back into the wild or donated to aquariums. Often, in cases of atypical coloring, there is a genetic factor, such as albinism or hermaphroditism. Special coloring does not appear to affect the lobster's taste once cooked; except for albinos, all lobsters possess astaxanthin, which is responsible for the bright red color lobsters turn after being cooked.
Longevity
Lobsters live up to an estimated 45 to 50 years in the wild, although determining age is difficult: it is typically estimated from size and other variables. Newer techniques may lead to more accurate age estimates.
Research suggests that lobsters may not slow down, weaken, or lose fertility with age and that older lobsters may be more fertile than younger lobsters. This longevity may be due to telomerase, an enzyme that repairs long repetitive sections of DNA sequences at the ends of chromosomes, referred to as telomeres. Telomerase is expressed by most vertebrates during embryonic stages but is generally absent from adult stages of life. However, unlike most vertebrates, lobsters express telomerase as adults through most tissue, which has been suggested to be related to their longevity. Telomerase is especially present in green spotted lobsters, whose markings are thought to be produced by the enzyme interacting with their shell pigmentation. Lobster longevity is limited by their size. Moulting requires metabolic energy, and the larger the lobster, the more energy is needed; 10 to 15% of lobsters die of exhaustion during moulting, while in older lobsters, moulting ceases and the exoskeleton degrades or collapses entirely, leading to death.
Like many decapod crustaceans, lobsters grow throughout life and can add new muscle cells at each moult. Lobster longevity allows them to reach impressive sizes. According to Guinness World Records, the largest lobster ever caught was in Nova Scotia, Canada, weighing . | Lobster | Wikipedia | 475 | 46310 | https://en.wikipedia.org/wiki/Lobster | Biology and health sciences | Crustaceans | null |
Ecology
Lobsters live in all oceans, on rocky, sandy, or muddy bottoms from the shoreline to beyond the edge of the continental shelf, contingent largely on size and age. Smaller, younger lobsters are typically found in crevices or in burrows under rocks and do not typically migrate. Larger, older lobsters are more likely to be found in deeper seas, migrating back to shallow waters seasonally.
Lobsters are omnivores and typically eat live prey such as fish, mollusks, other crustaceans, worms, and some plant life. They scavenge if necessary and are known to resort to cannibalism in captivity. However, when lobster skin is found in lobster stomachs, this is not necessarily evidence of cannibalism because lobsters eat their shed skin after moulting. While cannibalism was thought to be nonexistent among wild lobster populations, it was observed in 2012 by researchers studying wild lobsters in Maine. These first known instances of lobster cannibalism in the wild are theorized to be attributed to a local population explosion among lobsters caused by the disappearance of many of the Maine lobsters' natural predators.
In general, lobsters are long and move by slowly walking on the sea floor. However, they swim backward quickly when they flee by curling and uncurling their abdomens. A speed of has been recorded. This is known as the caridoid escape reaction.
Symbiotic animals of the genus Symbion, the only known member of the phylum Cycliophora, live exclusively on lobster gills and mouthparts. Different species of Symbion have been found on the three commercially important lobsters of the North Atlantic Ocean: Nephrops norvegicus, Homarus gammarus, and Homarus americanus.
As food
Lobster is commonly served boiled or steamed in the shell. Diners crack the shell with lobster crackers and fish out the meat with lobster picks. The meat is often eaten with melted butter and lemon juice. Lobster is also used in soup, bisque, lobster rolls, cappon magro, and dishes such as lobster Newberg and lobster Thermidor.
Cooks boil or steam live lobsters. When a lobster is cooked, its shell's color changes from brown to orange because the heat from cooking breaks down a protein called crustacyanin, which suppresses the orange hue of the chemical astaxanthin, which is also found in the shell. | Lobster | Wikipedia | 509 | 46310 | https://en.wikipedia.org/wiki/Lobster | Biology and health sciences | Crustaceans | null |
According to the United States Food and Drug Administration (FDA), the mean level of mercury in American lobster between 2005 and 2007 was 0.107ppm.
History
Humans are claimed to have eaten lobster since early history. Large piles of lobster shells near areas populated by fishing communities attest to the crustacean's extreme popularity during this period. Evidence indicates that lobster was being consumed as a regular food product in fishing communities along the shores of Britain, South Africa, Australia, and Papua New Guinea years ago. Lobster became a significant source of nutrients among European coastal dwellers. Historians suggest lobster was an important secondary food source for most European coastal dwellers, and it was a primary food source for coastal communities in Britain during this time.
Lobster became a popular mid-range delicacy during the mid to late Roman period. The price of lobster could vary widely due to various factors, but evidence indicates that lobster was regularly transported inland over long distances to meet popular demand. A mosaic found in the ruins of Pompeii suggests that the spiny lobster was of considerable interest to the Roman population during the early imperial period.
Lobster was a popular food among the Moche people of Peru between 50 CE and 800 CE. Besides its use as food, lobster shells were also used to create a light pink dye, ornaments, and tools. A mass-produced lobster-shaped effigy vessel dated to this period attests to lobster's popularity at this time, though the purpose of this vessel has not been identified.
The Viking period saw an increase in lobster and other shellfish consumption among northern Europeans. This can be attributed to the overall increase in marine activity due to the development of better boats and the increasing cultural investment in building ships and training sailors. The consumption of marine life went up overall in this period, and the consumption of lobster went up in accordance with this general trend.
Unlike fish, however, lobster had to be cooked within two days of leaving salt water, limiting the availability of lobster for inland dwellers. Thus lobster, more than fish, became a food primarily available to the relatively well-off, at least among non-coastal dwellers. | Lobster | Wikipedia | 431 | 46310 | https://en.wikipedia.org/wiki/Lobster | Biology and health sciences | Crustaceans | null |
Lobster is first mentioned in cookbooks during the medieval period. Le Viandier de Taillevent, a French recipe collection written around 1300, suggests that lobster (also called saltwater crayfish) be "Cooked in wine and water, or in the oven; eaten in vinegar." Le Viandier de Taillevent is considered to be one of the first "haute cuisine" cookbooks, advising on how to cook meals that would have been quite elaborate for the period and making usage of expensive and hard to obtain ingredients. Though the original edition, which includes the recipe for lobster, was published before the birth of French court cook Guillaume Tirel, Tirel later expanded and republished this recipe collection, suggesting that the recipes included in both editions were popular among the highest circles of French nobility, including King Philip VI. The inclusion of a lobster recipe in this cookbook, especially one which does not make use of other more expensive ingredients, attests to the popularity of lobster among the wealthy.
The French household guidebook Le Ménagier de Paris, published in 1393, includes no less than five recipes including lobster, which vary in elaboration. A guidebook intended to provide advice for women running upper-class households, Le Ménagier de Paris is similar to its predecessor in that it indicates the popularity of lobster as a food among the upper classes.
That lobster was first mentioned in cookbooks during the 1300s and only mentioned in two during this century should not be taken as an implication that lobster was not widely consumed before or during this time. Recipe collections were virtually non-existent before the 1300s, and only a handful exist from the medieval period. | Lobster | Wikipedia | 338 | 46310 | https://en.wikipedia.org/wiki/Lobster | Biology and health sciences | Crustaceans | null |
During the early 1400s, lobster was still a popular dish among the upper classes. During this time, influential households used the variety and variation of species served at feasts to display wealth and prestige. Lobster was commonly found among these spreads, indicating that it continued to be held in high esteem among the wealthy. In one notable instance, the Bishop of Salisbury offered at least 42 kinds of crustaceans and fish at his feasts over nine months, including several varieties of lobster. However, lobster was not a food exclusively accessed by the wealthy. The general population living on the coasts made use of the various food sources provided by the ocean, and shellfish especially became a more popular source of nutrition. Among the general population, lobster was generally eaten boiled during the mid-15th century, but the influence of the cuisine of higher society can be seen in that it was now also regularly eaten cold with vinegar. The inland peasantry would still have generally been unfamiliar with lobster during this time.
Lobster continued to be eaten as a delicacy and a general staple food among coastal communities until the late 17th century. During this time, the influence of the Church and the government regulating and sometimes banning meat consumption during certain periods continued to encourage the popularity of seafood, especially shellfish, as a meat alternative among all classes. Throughout this period, lobster was eaten fresh, pickled, and salted. From the late 17th century onward, developments in fishing, transportation, and cooking technology allowed lobster to more easily make its way inland, and the variety of dishes involving lobster and cooking techniques used with the ingredient expanded. However, these developments coincided with a decrease in the lobster population, and lobster increasingly became a delicacy food, valued among the rich as a status symbol and less likely to be found in the diet of the general population. | Lobster | Wikipedia | 365 | 46310 | https://en.wikipedia.org/wiki/Lobster | Biology and health sciences | Crustaceans | null |
The American lobster was not originally popular among European colonists in North America. This was partially due to the European inlander's association of lobster with barely edible salted seafood and partially due to a cultural opinion that seafood was a lesser alternative to meat that did not provide the taste or nutrients desired. It was also due to the extreme abundance of lobster at the time of the colonists' arrival, which contributed to a general perception of lobster as an undesirable peasant food. The American lobster did not achieve popularity until the mid-19th century when New Yorkers and Bostonians developed a taste for it, and commercial lobster fisheries only flourished after the development of the lobster smack, a custom-made boat with open holding wells on the deck to keep the lobsters alive during transport.
Before this time, lobster was considered a poverty food or as a food for indentured servants or lower members of society in Maine, Massachusetts, and the Canadian Maritimes. Some servants specified in employment agreements that they would not eat lobster more than twice per week, however there is limited evidence for this. Lobster was also commonly served in prisons, much to the displeasure of inmates. American lobster was initially deemed worthy only of being used as fertilizer or fish bait, and until well into the 20th century, it was not viewed as more than a low-priced canned staple food.
As a crustacean, lobster remains a taboo food in the dietary laws of Judaism and certain streams of Islam.
Grading
Caught lobsters are graded as new-shell, hard-shell, or old-shell. Because lobsters that have recently shed their shells are the most delicate, an inverse relationship exists between the price of American lobster and its flavor. New-shell lobsters have paper-thin shells and a worse meat-to-shell ratio, but the meat is very sweet. However, the lobsters are so delicate that even transport to Boston almost kills them, making the market for new-shell lobsters strictly local to the fishing towns where they are offloaded. Hard-shell lobsters with firm shells but less sweet meat can survive shipping to Boston, New York, and even Los Angeles, so they command a higher price than new-shell lobsters. Meanwhile, old-shell lobsters, which have not shed since the previous season and have a coarser flavor, can be air-shipped anywhere in the world and arrive alive, making them the most expensive.
Killing methods and animal welfare | Lobster | Wikipedia | 495 | 46310 | https://en.wikipedia.org/wiki/Lobster | Biology and health sciences | Crustaceans | null |
Several methods are used for killing lobsters. The most common way of killing lobsters is by placing them live in boiling water, sometimes after being placed in a freezer for a period. Another method is to split the lobster or sever the body in half lengthwise. Lobsters may also be killed or immobilized immediately before boiling by a stab into the brain (pithing), in the belief that this will stop suffering. However, a lobster's brain operates from not one but several ganglia, and disabling only the frontal ganglion does not usually result in death. The boiling method is illegal in some places, such as in Italy, where offenders face fines up to €495. Lobsters can be killed by electrocution prior to cooking with a device called the CrustaStun. Since March 2018, lobsters in Switzerland need to be knocked out, or killed instantly, before they are boiled. They also receive other forms of protection while in transit.
Fishery and aquaculture
Lobsters are caught using baited one-way traps with a color-coded marker buoy to mark cages. Lobster is fished in water between , although some lobsters live at . Cages are of plastic-coated galvanized steel or wood. A lobster fisher may tend to as many as 2,000 traps.
Around the year 2000, owing to overfishing and high demand, lobster aquaculture expanded.
Species
The fossil record of clawed lobsters extends back at least to the Valanginian age of the Cretaceous (140 million years ago). This list contains all 54 extant species in the family Nephropidae: | Lobster | Wikipedia | 330 | 46310 | https://en.wikipedia.org/wiki/Lobster | Biology and health sciences | Crustaceans | null |
Acanthacaris
Acanthacaris caeca A. Milne-Edwards, 1881
Acanthacaris tenuimana Bate, 1888
Dinochelus Ahyong, Chan & Bouchet, 2010
Dinochelus ausubeli Ahyong, Chan & Bouchet, 2010
Eunephrops Smith, 1885
Eunephrops bairdii Smith, 1885
Eunephrops cadenasi Chace, 1939
Eunephrops luckhursti Manning, 1997
Eunephrops manningi Holthuis, 1974
Homarinus Kornfield, Williams & Steneck, 1995
Homarinus capensis (Herbst, 1792) – Cape lobster
Homarus Weber, 1795
Homarus americanus H. Milne-Edwards, 1837 – American lobster
Homarus gammarus (Linnaeus, 1758) – European lobster
Metanephrops Jenkins, 1972
Metanephrops andamanicus (Wood-Mason, 1892) – Andaman lobster
Metanephrops arafurensis (De Man, 1905)
Metanephrops armatus Chan & Yu, 1991
Metanephrops australiensis (Bruce, 1966) – Australian scampi
Metanephrops binghami (Boone, 1927) – Caribbean lobster
Metanephrops boschmai (Holthuis, 1964) – Bight lobster
Metanephrops challengeri (Balss, 1914) – New Zealand scampi
Metanephrops formosanus Chan & Yu, 1987
Metanephrops japonicus (Tapparone-Canefri, 1873) – Japanese lobster
Metanephrops mozambicus Macpherson, 1990
Metanephrops neptunus (Bruce, 1965)
Metanephrops rubellus (Moreira, 1903)
Metanephrops sagamiensis (Parisi, 1917)
Metanephrops sibogae (De Man, 1916)
Metanephrops sinensis (Bruce, 1966) – China lobster
Metanephrops taiwanicus (Hu, 1983)
Metanephrops thomsoni (Bate, 1888)
Metanephrops velutinus Chan & Yu, 1991
Nephropides Manning, 1969
Nephropides caribaeus Manning, 1969
Nephrops Leach, 1814
Nephrops norvegicus (Linnaeus, 1758) – Norway lobster, Dublin Bay prawn, langoustine | Lobster | Wikipedia | 504 | 46310 | https://en.wikipedia.org/wiki/Lobster | Biology and health sciences | Crustaceans | null |
Nephropsis Wood-Mason, 1872
Nephropsis acanthura Macpherson, 1990
Nephropsis aculeata Smith, 1881 – Florida lobsterette
Nephropsis agassizii A. Milne-Edwards, 1880
Nephropsis atlantica Norman, 1882
Nephropsis carpenteri Wood-Mason, 1885
Nephropsis ensirostris Alcock, 1901
Nephropsis holthuisii Macpherson, 1993
Nephropsis malhaensis Borradaile, 1910
Nephropsis neglecta Holthuis, 1974
Nephropsis occidentalis Faxon, 1893
Nephropsis rosea Bate, 1888
Nephropsis serrata Macpherson, 1993
Nephropsis stewarti Wood-Mason, 1872
Nephropsis suhmi Bate, 1888
Nephropsis sulcata Macpherson, 1990
Thaumastocheles Wood-Mason, 1874
Thaumastocheles dochmiodon Chan & Saint Laurent, 1999
Thaumastocheles japonicus Calman, 1913
Thaumastocheles zaleucus (Thomson, 1873)
Thaumastochelopsis Bruce, 1988
Thaumastochelopsis brucei Ahyong, Chu & Chan, 2007
Thaumastochelopsis wardi Bruce, 1988
Thymopides Burukovsky & Averin, 1977
Thymopides grobovi (Burukovsky & Averin, 1976)
Thymopides laurentae Segonzac & Macpherson, 2003
Thymops Holthuis, 1974
Thymops birsteini (Zarenkov & Semenov, 1972)
Thymopsis Holthuis, 1974
Thymopsis nilenta Holthuis, 1974 | Lobster | Wikipedia | 360 | 46310 | https://en.wikipedia.org/wiki/Lobster | Biology and health sciences | Crustaceans | null |
Flounders are a group of flatfish species. They are demersal fish, found at the bottom of oceans around the world; some species will also enter estuaries.
Taxonomy
The name "flounder" is used for several only distantly related species, though all are in the suborder Pleuronectoidei (families Achiropsettidae, Bothidae, Pleuronectidae, Paralichthyidae, and Samaridae). Some of the better known species that are important in fisheries are:
Western Atlantic
Gulf flounder – Paralichthys albigutta
Southern flounder – Paralichthys lethostigma
Summer flounder (also known as fluke) – Paralichthys dentatus
Winter flounder – Pseudopleuronectes americanus
European waters
European flounder – Platichthys flesus
Witch flounder – Glyptocephalus cynoglossus
North Pacific
Halibut – Hippoglossus stenolepis
Olive flounder – Paralichthys olivaceus
Eye migration
Larval flounder are born with one eye on each side of their head, but as they grow from the larval to juvenile stage through metamorphosis, one eye migrates to the other side of the body. As a result, both eyes are then on the side which faces up. The side to which the eyes migrate is dependent on the species type. As an adult, a flounder changes its habits and camouflages itself by lying on the bottom of the ocean floor as protection against predators.
Habitat
Flounders ambush their prey, feeding at soft muddy areas of the sea bottom, near bridge piles, docks, and coral reefs.
A flounder's diet consists mainly of fish spawn, crustaceans, polychaetes and small fish. Flounder typically grow to a length of , and as large as . Their width is about half their length. Male Platichthys have been found up to off the coast of northern Sardinia, sometimes with heavy encrustations of various species of barnacle.
Fluke, a type of flounder, are being farm raised in open water by Mariculture Technologies in Greenport, New York.
Threats | Flounder | Wikipedia | 471 | 46311 | https://en.wikipedia.org/wiki/Flounder | Biology and health sciences | Acanthomorpha | null |
World stocks of large predatory fish and large ground fish, including sole and flounder, were estimated in 2003 to be only about 10% of pre-industrial levels, largely due to overfishing. Most overfishing is due to the extensive activities of the fishing industry. Current estimates suggest that approximately 30 million flounder (excluding sole) are alive in the world today. In the Gulf of Mexico, along the coast of Texas, research indicates the flounder population could be as low as 15 million due to heavy overfishing and industrial pollution. | Flounder | Wikipedia | 113 | 46311 | https://en.wikipedia.org/wiki/Flounder | Biology and health sciences | Acanthomorpha | null |
Asparagus (Asparagus officinalis) is a perennial flowering plant species in the genus Asparagus native to Eurasia. Widely cultivated as a vegetable crop, its young shoots are used as a spring vegetable.
Description
Asparagus is an herbaceous, perennial plant growing to tall, with stout stems with much-branched, feathery foliage. The 'leaves' are needle-like cladodes (modified stems) in the axils of scale leaves; they are long and broad, and clustered in fours, up to 15, together, in a rose-like shape. The root system, often referred to as a 'crown', is adventitious; the root type is fasciculated. The flowers are bell-shaped, greenish-white to yellowish, long, with six tepals partially fused together at the base; they are produced singly or in clusters of two or three in the junctions of the branchlets. It is usually dioecious, with male and female flowers on separate plants, but sometimes hermaphrodite flowers are found. The fruit is a small red berry in diameter, which is toxic to humans.
Plants native to the western coasts of Europe (from northern Spain to northwest Germany, north Ireland, and Great Britain) are treated as A. officinalis subsp. prostratus , distinguished by its low-growing, often prostrate stems growing to only high, and shorter cladodes long. Some authors treat it as a distinct species, A. prostratus .
Taxonomy
Asparagus was once classified in the lily family, as were the related Allium species onions and garlic. Genetic research currently places lilies, Allium, and asparagus in three separate families: the Liliaceae, Amaryllidaceae, and Asparagaceae, respectively. The latter two are part of the order Asparagales.
Etymology
The English word asparagus derives from classical Latin but the plant was once known in English as sperage, from the Medieval Latin sparagus. This term itself derives from the - aspáragos, a variant of - aspháragos. The Greek terms are of uncertain provenance; the former form admits the possibility of a Proto-Indo-European root meaning "to jerk, scatter," directly or via a Persian descendant meaning "twig, branch"; but the Ancient Greek word itself, meaning "gully, chasm," seems to be of Pre-Greek origin instead. | Asparagus | Wikipedia | 508 | 46319 | https://en.wikipedia.org/wiki/Asparagus | Biology and health sciences | Monocots | null |
In English, A. officinalis is widely known simply as "asparagus", or sometimes "garden asparagus".
Asparagus was corrupted by folk etymology in some places to "sparrow grass"; indeed, John Walker wrote in 1791 that "Sparrowgrass is so general that asparagus has an air of stiffness and pedantry".
The name 'sparrow grass' was still in common use in rural East Anglia, England well into the twentieth century.
Distribution and habitat
Sources differ as to the plant's native range, but generally include most of Europe and western temperate Asia.
Cultivation
Since asparagus often originates in maritime habitats, it thrives in soils that are too saline for normal weeds to grow. Thus, a little salt was traditionally used to suppress weeds in beds intended for asparagus; this has the disadvantage that the soil cannot be used for anything else. Some regions and gardening zones are better-suited for growing asparagus than others, such as the west coast of North America and other more maritime, “Mediterranean” environments. The fertility of the soil is a large factor. "Crowns" are planted in winter, and the first shoots appear in spring; the first pickings or "thinnings" are known as sprue asparagus. Sprue has thin stems.
A breed of "early-season asparagus" that can be harvested two months earlier than usual was announced by a UK grower in early 2011. This variety does not need to lie dormant and blooms at , rather than the usual .
Purple asparagus differs from its green and white counterparts in having high sugar and low fibre levels. Purple asparagus was originally developed in Italy, near the city of Albenga and commercialized under the variety name 'Violetto d' Albenga'. Purple asparagus can also turn green while being cooked due to its sensitivity to heat.
Companion planting
Asparagus is said to be a useful companion plant for tomatoes, as the tomato plant repels the asparagus beetle. Asparagus may repel some harmful root nematodes that affect tomato plants.
Uses
The genome of the species has been sequenced as a model to study the evolution of sex chromosomes in plants and dioecy. | Asparagus | Wikipedia | 463 | 46319 | https://en.wikipedia.org/wiki/Asparagus | Biology and health sciences | Monocots | null |
Nutrition
Water makes up 93% of asparagus's composition. Asparagus is low in food energy and very low in sodium. It is a good source of vitamin B6, calcium, magnesium, and zinc, and a very good source of dietary fibre, protein, beta-carotene, vitamin C, vitamin E, vitamin K, thiamin, riboflavin, rutin, niacin, folic acid, iron, phosphorus, potassium, copper, manganese, and selenium, as well as chromium, a trace mineral that regulates the ability of insulin to transport glucose from the bloodstream into cells. The amino acid asparagine gets its name from asparagus, from which it was first isolated, as the asparagus plant is relatively rich in this compound.
Culinary
Only young asparagus shoots are commonly eaten: once the buds start to open ("ferning out"), the shoots quickly turn woody. The roots contain starch.
The shoots are prepared and served in a number of ways around the world, typically as an appetizer or vegetable side dish. In Asian-style cooking, asparagus is often stir-fried. Cantonese restaurants in the United States often serve asparagus stir-fried with chicken, shrimp, or beef. It may also be quickly grilled over charcoal or hardwood embers, and is also used as an ingredient in some stews and soups.
Asparagus can also be pickled and stored for several years. Some brands label shoots prepared in this way as "marinated".
Stem thickness indicates the age of the plant (and not the age of the stalk), with the thicker stems coming from older plants. Older, thicker stalks can be woody, although peeling the skin at the base removes the tough layer. Peeled asparagus will poach much faster. The bottom portion of asparagus often contains sand and soil, so thorough cleaning is generally advised before cooking.
Male plants tend to produce spears that are smaller and thinner, while female plants tend produce larger and thicker spears. Thickness and thinness are not an indication of tenderness or toughness. The stalks are thick or thin from the moment they sprout from the ground. | Asparagus | Wikipedia | 457 | 46319 | https://en.wikipedia.org/wiki/Asparagus | Biology and health sciences | Monocots | null |
Green asparagus is eaten worldwide, and the availability of imports throughout the year has made it less of a delicacy than it once was. In Europe, according to one source, the "asparagus season is a highlight of the foodie calendar"; in the UK this traditionally begins on 23 April and ends on Midsummer Day. As in continental Europe, due to the short growing season and demand for local produce, asparagus commands a premium price.
Commercial production
The top asparagus importers (2016) were the United States (214,735 tonnes), followed by Germany (24,484 tonnes), and Canada (19,224 tonnes).
China is by far the world's largest producer: in 2017 it produced 7,845,162 tonnes, followed by Peru with 383,098 tonnes and Mexico with 245,681 tonnes. U.S. production was concentrated in California, Michigan, and Washington.
The annual production for white asparagus in Germany is 57,000 tonnes (61% of consumer demand).
When grown under tunnels, growers can extend the harvest season. In the UK, it is estimated that the asparagus harvest season can begin as early as mid-February and continue into late autumn by growing cold-resistant cultivars under heated polytunnels. Furthermore, late season harvests can be achieved using 'reverse season growth' where spears are left to fern between March–August and harvested in September–October.
In Asia, an alternative approach to cultivating asparagus has been employed and is referred to as 'Mother Stalk Method' where three to five stalks per plant are allowed to develop into fern, while harvesting adjacent spears.
White asparagus
White asparagus is very popular in Europe and western Asia. White asparagus is the result of applying a blanching technique while the asparagus shoots are growing. To cultivate white asparagus, the shoots are covered with soil as they grow, i.e. earthed up; without exposure to sunlight, no photosynthesis starts, and the shoots remain white. Compared to green asparagus, the locally cultivated so-called "white gold" or "edible ivory" asparagus, also referred to as "the royal vegetable", is believed to be less bitter and much more tender. Freshness is very important, and the lower ends of white asparagus must be peeled before cooking or raw consumption. | Asparagus | Wikipedia | 502 | 46319 | https://en.wikipedia.org/wiki/Asparagus | Biology and health sciences | Monocots | null |
Only seasonally on the menu, asparagus dishes are advertised outside many restaurants, usually from late April to June. For the French style, asparagus is often boiled or steamed and served with Hollandaise sauce, white sauce, melted butter or most recently with olive oil and Parmesan cheese. Tall, narrow asparagus cooking pots allow the shoots to be steamed gently, their tips staying out of the water.
During the German Spargelsaison or Spargelzeit ("asparagus season" or "asparagus time"), the asparagus season that traditionally finishes on 24 June, roadside stands and open-air markets sell about half of the country's white asparagus consumption.
In western Himalayan regions, such as Nepal and north-western India, wild asparagus is harvested as a seasonal vegetable delicacy known as kurilo or jhijhirkani.
In culture
Asparagus has been used as a vegetable owing to its distinct flavor, and in medicine due to its diuretic properties and its purported function as an aphrodisiac. It is pictured as an offering on an Egyptian frieze dating to 3000 BC. In ancient times, it was also known in Syria and in the Iberian Peninsula. Greeks and Romans ate it fresh when in season, and dried the vegetable for use in winter. Emperor Augustus coined the expression "faster than cooking asparagus" for quick action.
A recipe for cooking asparagus is given in one of the oldest surviving collections of recipes (Apicius's 1st century AD De re coquinaria, Book III). In the second century AD, the Greek physician Galen, highly respected within Roman society, mentioned asparagus as a beneficial herb, but as dominance of the Roman empire waned, asparagus' medicinal value drew little attention
until al-Nafzawi's The Perfumed Garden. That piece of writing celebrates its purported aphrodisiacal power that the Indian Ananga Ranga attributes to "special phosphorus elements" that also counteract fatigue.
By 1469, asparagus was cultivated in French monasteries. Asparagus appears to have been little noticed in England until 1538, and in Germany until 1542. | Asparagus | Wikipedia | 460 | 46319 | https://en.wikipedia.org/wiki/Asparagus | Biology and health sciences | Monocots | null |
Asparagus was brought to North America by European settlers at least as early as 1655. Adriaen van der Donck, a Dutch immigrant to New Netherland, mentions asparagus in his description of Dutch farming practices in the New World. Asparagus was grown by British immigrants as well; in 1685, one of William Penn's advertisements for Pennsylvania included asparagus in a long list of crops that grew well in the American climate.
The points d'amour ("love tips") were served as a delicacy to Madame de Pompadour (1721–1764).
Effects on urine
The effect of eating asparagus on urine excreted afterwards has long been observed:
[Asparagus] cause a powerful and disagreeable smell in the urine, as everybody knows.
— Treatise of All Sorts of Foods, Louis Lémery, 1702
asparagus... affects the urine with a foetid smell (especially if cut when they are white) and therefore have been suspected by some physicians as not friendly to the kidneys; when they are older, and begin to ramify, they lose this quality; but then they are not so agreeable.
— "An Essay Concerning the Nature of Aliments", John Arbuthnot, 1735
A few Stems of Asparagus eaten, shall give our Urine a disagreeable Odour...
— "Letter to the Royal Academy of Brussels", Benjamin Franklin, c. 1781
Asparagus "...transforms my chamber-pot into a flask of perfume."
— Marcel Proust (1871–1922)
Asparagus contains asparagusic acid. When the vegetable is digested, a group of volatile sulfur-containing compounds is produced.
Certain compounds in asparagus are metabolized to yield ammonia and various sulfur-containing degradation products, including various thiols and thioesters, which following consumption give urine a characteristic smell. Some of the volatile organic compounds responsible for the smell are:
methanethiol
dimethyl sulfide
dimethyl disulfide
bis(methylthio)methane
dimethyl sulfoxide
dimethyl sulfone | Asparagus | Wikipedia | 444 | 46319 | https://en.wikipedia.org/wiki/Asparagus | Biology and health sciences | Monocots | null |
Subjectively, the first two are the most pungent, while the last two (sulfur-oxidized) give a sweet aroma. A mixture of these compounds form a "reconstituted asparagus urine" odor. This was first investigated in 1891 by Marceli Nencki, who attributed the smell to methanethiol. These compounds originate in the asparagus as asparagusic acid and its derivatives, as these are the only sulfur-containing compounds unique to asparagus. As these are more present in young asparagus, this accords with the observation that the smell is more pronounced after eating young asparagus. The biological mechanism for the production of these compounds is less clear.
The onset of the asparagus urine smell is remarkably rapid while the decline is slower. The smell has been reported to be detectable 15 to 30 minutes after ingestion and subsides with a half-life of approximately four hours.
Asparagus has been eaten and cultivated for at least two millennia but the association between odorous urine and asparagus consumption was not observed until the late 17th century when sulfur-rich fertilisers became common in agriculture. Small-scale studies noted that the "asparagus urine" odour was not produced by all individuals and estimates as to the proportion of the population who are excretors (reporting a noticeable asparagus urine odour after eating asparagus) has ranged from about 40% to as high as 79%. When excretors are exposed to non-excretor urine after asparagus consumption, however, the characteristic asparagus urine odour is usually reported. More recent work has confirmed that a small proportion of individuals do not produce asparagus urine, and amongst those that do, some cannot detect the odour due to a single-nucleotide polymorphism within a cluster of olfactory receptors. | Asparagus | Wikipedia | 389 | 46319 | https://en.wikipedia.org/wiki/Asparagus | Biology and health sciences | Monocots | null |
Debate exists about the universality of producing the sulfurous smell, as well as the ability to detect it. Originally, this was thought to be because some people digested asparagus differently from others, so some excreted odorous urine after eating asparagus, and others did not. In the 1980s, three studies from France, China, and Israel published results showing that producing odorous urine from asparagus was a common human characteristic. The Israeli study found that from their 307 subjects, all of those who could smell "asparagus urine" could detect it in the urine of anyone who had eaten asparagus, even if the person who produced it could not detect it. A 2010 study found variations in both production of odorous urine and the ability to detect the odor, but that these were not tightly related. Most people are thought to produce the odorous compounds after eating asparagus, but the differing abilities of various individuals to detect the odor at increasing dilutions suggests a genetically determined specific sensitivity.
In 2010, the company 23andMe published a genome-wide association study on whether participants have "ever noticed a peculiar odor when [they] pee after eating asparagus". This study pinpointed a single-nucleotide polymorphism (SNP) in a cluster of olfactory genes associated with the ability to detect the odor. While this SNP did not explain all of the difference in detection between people, it provides support for the theory that genetic differences occur in olfactory receptors that lead people to be unable to smell these odorous compounds.
Celebrations
The green crop is significant enough in California's Sacramento–San Joaquin River Delta region that the city of Stockton holds a festival every year to celebrate it. Oceana County, Michigan, the self-proclaimed "asparagus capital of the world" hosts an annual festival complete with a parade and asparagus queen; The Vale of Evesham in Worcestershire is the largest producer within Northern Europe, celebrating with the annual British Asparagus Festival involving auctions of the best crop, an "Asparagus Run" modelled on the Beaujolais Run and a weekend "Asparafest" music festival. | Asparagus | Wikipedia | 442 | 46319 | https://en.wikipedia.org/wiki/Asparagus | Biology and health sciences | Monocots | null |
Many German cities hold an annual Spargelfest (asparagus festival) celebrating the harvest of white asparagus. Schwetzingen claims to be the "Asparagus Capital of the World", and during its festival, an Asparagus Queen is crowned. The Bavarian city of Nuremberg feasts a week long in April, with a competition to find the fastest asparagus peeler in the region; this usually involves generous amounts of the local wines and beers being consumed to aid the spectators' appreciative support.
Helmut Zipner, who peeled a ton of asparagus in 16 hours, holds the world record in asparagus peeling.
Gallery | Asparagus | Wikipedia | 137 | 46319 | https://en.wikipedia.org/wiki/Asparagus | Biology and health sciences | Monocots | null |
A flatfish is a member of the ray-finned demersal fish superorder Pleuronectoidei, also called the Heterosomata. In many species, both eyes lie on one side of the head, one or the other migrating through or around the head during development. Some species face their left sides upward, some face their right sides upward, and others face either side upward. The most primitive members of the group, the threadfins, do not resemble the flatfish but are their closest relatives.
Many important food fish are in this order, including the flounders, soles, turbot, plaice, and halibut. Some flatfish can camouflage themselves on the ocean floor.
Taxonomy
Due to their highly distinctive morphology, flatfishes were previously treated as belonging to their own order, Pleuronectiformes. However, more recent taxonomic studies have found them to group within a diverse group of nektonic marine fishes known as the Carangiformes, which also includes jacks and billfish. Specifically, flatfish are most closely related to the threadfins, which are now also placed in the suborder Pleuronectoidei. Together, the group is most closely related to the archerfish and beachsalmons within Toxotoidei. Due to this, they are now treated as a suborder of the Carangiformes. | Flatfish | Wikipedia | 289 | 46331 | https://en.wikipedia.org/wiki/Flatfish | Biology and health sciences | Acanthomorpha | null |
Over 800 described species are placed into 16 families. When they were treated as an order, the flatfishes are divided into two suborders, Psettodoidei and Pleuronectoidei, with > 99% of the species diversity found within the Pleuronectoidei. The largest families are Soleidae, Bothidae and Cynoglossidae with more than 150 species each. There also exist two monotypic families (Paralichthodidae and Oncopteridae). Some families are the results of relatively recent splits. For example, the Achiridae were classified as a subfamily of Soleidae in the past, and the Samaridae were considered a subfamily of the Pleuronectidae. The families Paralichthodidae, Poecilopsettidae, and Rhombosoleidae were also traditionally treated as subfamilies of Pleuronectidae, but are now recognised as families in their own right. The Paralichthyidae has long been indicated to be paraphyletic, with the formal description of Cyclopsettidae in 2019 resulting in the split of this family as well.
The taxonomy of some groups is in need of a review. The last monograph covering the entire order was John Roxborough Norman's Monograph of the Flatfishes published in 1934. In particular, Tephrinectes sinensis may represent a family-level lineage and requires further evaluation e.g. New species are described with some regularity and undescribed species likely remain.
Hybrids
Hybrids are well known in flatfishes. The Pleuronectidae have the largest number of reported hybrids of marine fishes. Two of the most famous intergeneric hybrids are between the European plaice (Pleuronectes platessa) and European flounder (Platichthys flesus) in the Baltic Sea, and between the English sole (Parophrys vetulus) and starry flounder (Platichthys stellatus) in Puget Sound. The offspring of the latter species pair is popularly known as the hybrid sole and was initially believed to be a valid species in its own right. | Flatfish | Wikipedia | 447 | 46331 | https://en.wikipedia.org/wiki/Flatfish | Biology and health sciences | Acanthomorpha | null |
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