text:
Nuclear fallout

Nuclear fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and the shock wave has passed. It commonly refers to the radioactive dust and ash created when a nuclear weapon explodes. The amount and spread of fallout is a product of the size of the weapon and the altitude at which it is detonated. Fallout may get entrained with the products of a pyrocumulus cloud and fall as black rain (rain darkened by soot and other particulates, which fell within 30–40 minutes of the atomic bombings of Hiroshima and Nagasaki). This radioactive dust, usually consisting of fission products mixed with bystanding atoms that are neutron-activated by exposure, is a form of radioactive contamination.

Types of fallout

Fallout comes in two varieties. The first is a small amount of carcinogenic material with a long half-life. The second, depending on the height of detonation, is a large quantity of radioactive dust and sand with a short half-life.

All nuclear explosions produce fission products, un-fissioned nuclear material, and weapon residues vaporized by the heat of the fireball. These materials are limited to the original mass of the device, but include radioisotopes with long lives. When the nuclear fireball does not reach the ground, this is the only fallout produced. Its amount can be estimated from the fission-fusion design and yield of the weapon.

Global fallout
After the detonation of a weapon at or above the fallout-free altitude (an air burst), fission products, un-fissioned nuclear material, and weapon residues vaporized by the heat of the fireball condense into a suspension of particles 10 nm to 20 μm in diameter. This size of particulate matter, lifted to the stratosphere, may take months or years to settle, and may do so anywhere in the world. Its radioactive characteristics increase the statistical cancer risk, with up to 2.4 million people having died by 2020 from the measurable elevated atmospheric radioactivity after the widespread nuclear weapons testing of the 1950s, peaking in 1963 (the Bomb pulse). Levels reached about 0.15 mSv per year worldwide, or about 7% of average background radiation dose from all sources, and has slowly decreased since, with natural background radiation levels being around 1 mSv.

Radioactive fallout has occurred around the world; for example, people have been exposed to iodine-131 from atmospheric nuclear testing. Fallout accumulates on vegetation, including fruits and vegetables. Starting from 1951 people may have gotten exposure, depending on whether they were outside, the weather, and whether they consumed contaminated milk, vegetables or fruit. Exposure can be on an intermediate time scale or long term. The intermediate time scale results from fallout that has been put into the troposphere and ejected by precipitation during the first month. Long-term fallout can sometimes occur from deposition of tiny particles carried in the stratosphere. By the time that stratospheric fallout has begun to reach the earth, the radioactivity is very much decreased. Also, after a year it is estimated that a sizable quantity of fission products move from the northern to the southern stratosphere. The intermediate time scale is between 1 and 30 days, with long term fallout occurring after that.

Examples of both intermediate and long term fallout occurred after the 1986 Chernobyl accident, which contaminated over 20000 km2 of land in Ukraine and Belarus. The main fuel of the reactor was uranium, and surrounding this was graphite, both of which were vaporized by the hydrogen explosion that destroyed the reactor and breached its containment. An estimated 31 people died within a few weeks after this happened, including two plant workers killed at the scene. Although residents were evacuated within 36 hours, people started to complain of vomiting, migraines and other major signs of radiation sickness. The officials of Ukraine had to close off an 18 mile area. Long term effects included at least 6,000 cases of thyroid cancer, mainly among children. Fallout spread throughout Western Europe, with Northern Scandinavia receiving a heavy dose, contaminating reindeer herds in Lapland, and salad greens becoming almost unavailable in France. Some sheep farms in North Wales and the North Of England were required to monitor radioactivity levels in their flocks until the control was lifted in 2012.

Local fallout
During detonations of devices at ground level (surface burst), below the fallout-free altitude, or in shallow water, heat vaporizes large amounts of earth or water, which is drawn up into the radioactive cloud. This material becomes radioactive when it combines with fission products or other radio-contaminants, or when it is neutron-activated.

The table below summarizes the abilities of common isotopes to form fallout. Some radiation taints large amounts of land and drinking water causing formal mutations throughout animal and human life.

A surface burst generates large amounts of particulate matter, composed of particles from less than 100 nm to several millimeters in diameter—in addition to very fine particles that contribute to worldwide fallout. The larger particles spill out of the stem and cascade down the outside of the fireball in a downdraft even as the cloud rises, so fallout begins to arrive near ground zero within an hour. More than half the total bomb debris lands on the ground within about 24 hours as local fallout. Chemical properties of the elements in the fallout control the rate at which they are deposited on the ground. Less volatile elements deposit first.

Severe local fallout contamination can extend far beyond the blast and thermal effects, particularly in the case of high yield surface detonations. The ground track of fallout from an explosion depends on the weather from the time of detonation onward. In stronger winds, fallout travels faster but takes the same time to descend, so although it covers a larger path, it is more spread out or diluted. Thus, the width of the fallout pattern for any given dose rate is reduced where the downwind distance is increased by higher winds. The total amount of activity deposited up to any given time is the same irrespective of the wind pattern, so overall casualty figures from fallout are generally independent of winds. But thunderstorms can bring down activity as rain allows fallout to drop more rapidly, particularly if the mushroom cloud is low enough to be below ("washout"), or mixed with ("rainout"), the thunderstorm.

Whenever individuals remain in a radiologically contaminated area, such contamination leads to an immediate external radiation exposure as well as a possible later internal hazard from inhalation and ingestion of radiocontaminants, such as the rather short-lived iodine-131, which is accumulated in the thyroid.

Location
There are two main considerations for the location of an explosion: height and surface composition. A nuclear weapon detonated in the air, called an air burst, produces less fallout than a comparable explosion near the ground. A nuclear explosion in which the fireball touches the ground pulls soil and other materials into the cloud and neutron activates it before it falls back to the ground. An air burst produces a relatively small amount of the highly radioactive heavy metal components of the device itself.

In case of water surface bursts, the particles tend to be rather lighter and smaller, producing less local fallout but extending over a greater area. The particles contain mostly sea salts with some water; these can have a cloud seeding effect causing local rainout and areas of high local fallout. Fallout from a seawater burst is difficult to remove once it has soaked into porous surfaces because the fission products are present as metallic ions that chemically bond to many surfaces. Water and detergent washing effectively removes less than 50% of this chemically bonded activity from concrete or steel. Complete decontamination requires aggressive treatment like sandblasting, or acidic treatment. After the Crossroads underwater test, it was found that wet fallout must be immediately removed from ships by continuous water washdown (such as from the fire sprinkler system on the decks).

Parts of the sea bottom may become fallout. After the Castle Bravo test, white dust—contaminated calcium oxide particles originating from pulverized and calcined corals—fell for several hours, causing beta burns and radiation exposure to the inhabitants of the nearby atolls and the crew of the Daigo Fukuryū Maru fishing boat. The scientists called the fallout Bikini snow.

For subsurface bursts, there is an additional phenomenon present called "base surge". The base surge is a cloud that rolls outward from the bottom of the subsiding column, which is caused by an excessive density of dust or water droplets in the air. For underwater bursts, the visible surge is, in effect, a cloud of liquid (usually water) droplets with the property of flowing almost as if it were a homogeneous fluid. After the water evaporates, an invisible base surge of small radioactive particles may persist.

For subsurface land bursts, the surge is made up of small solid particles, but it still behaves like a fluid. A soil earth medium favors base surge formation in an underground burst. Although the base surge typically contains only about 10% of the total bomb debris in a subsurface burst, it can create larger radiation doses than fallout near the detonation, because it arrives sooner than fallout, before much radioactive decay has occurred.

Meteorological

Meteorological conditions greatly influence fallout, particularly local fallout. Atmospheric winds are able to bring fallout over large areas. For example, as a result of a Castle Bravo surface burst of a 15 Mt thermonuclear device at Bikini Atoll on March 1, 1954, a roughly cigar-shaped area of the Pacific extending over 500 km downwind and varying in width to a maximum of 100 km was severely contaminated. There are three very different versions of the fallout pattern from this test, because the fallout was measured only on a small number of widely spaced Pacific Atolls. The two alternative versions both ascribe the high radiation levels at north Rongelap to a downwind hot spot caused by the large amount of radioactivity carried on fallout particles of about 50–100 micrometres size.

After Bravo, it was discovered that fallout landing on the ocean disperses in the top water layer (above the thermocline at 100 m depth), and the land equivalent dose rate can be calculated by multiplying the ocean dose rate at two days after burst by a factor of about 530. In other 1954 tests, including Yankee and Nectar, hot spots were mapped out by ships with submersible probes, and similar hot spots occurred in 1956 tests such as Zuni and Tewa. However, the major U.S. "DELFIC" (Defence Land Fallout Interpretive Code) computer calculations use the natural size distributions of particles in soil instead of the afterwind sweep-up spectrum, and this results in more straightforward fallout patterns lacking the downwind hot spot.

Snow and rain, especially if they come from considerable heights, accelerate local fallout. Under special meteorological conditions, such as a local rain shower that originates above the radioactive cloud, limited areas of heavy contamination just downwind of a nuclear blast may be formed.

Effects
A wide range of biological changes may follow the irradiation of animals. These vary from rapid death following high doses of penetrating whole-body radiation, to essentially normal lives for a variable period of time until the development of delayed radiation effects, in a portion of the exposed population, following low dose exposures.

The unit of actual exposure is the röntgen, defined in ionisations per unit volume of air. All ionisation based instruments (including geiger counters and ionisation chambers) measure exposure. However, effects depend on the energy per unit mass, not the exposure measured in air. A deposit of 1 joule per kilogram has the unit of 1 gray (Gy). For 1 MeV energy gamma rays, an exposure of 1 röntgen in air produces a dose of about 0.01 gray (1 centigray, cGy) in water or surface tissue. Because of shielding by the tissue surrounding the bones, the bone marrow only receives about 0.67 cGy when the air exposure is 1 röntgen and the surface skin dose is 1 cGy. Some lower values reported for the amount of radiation that would kill 50% of personnel (the ) refer to bone marrow dose, which is only 67% of the air dose.

Short term
The dose that would be lethal to 50% of a population is a common parameter used to compare the effects of various fallout types or circumstances. Usually, the term is defined for a specific time, and limited to studies of acute lethality. The common time periods used are 30 days or less for most small laboratory animals and to 60 days for large animals and humans. The LD50 figure assumes that the individuals did not receive other injuries or medical treatment.

In the 1950s, the LD50 for gamma rays was set at 3.5 Gy, while under more dire conditions of war (a bad diet, little medical care, poor nursing) the LD50 was 2.5 Gy (250 rad). There have been few documented cases of survival beyond 6 Gy. One person at Chernobyl survived a dose of more than 10 Gy, but many of the persons exposed there were not uniformly exposed over their entire body. If a person is exposed in a non-homogeneous manner then a given dose (averaged over the entire body) is less likely to be lethal. For instance, if a person gets a hand/low arm dose of 100 Gy, which gives them an overall dose of 4 Gy, they are more likely to survive than a person who gets a 4 Gy dose over their entire body. A hand dose of 10 Gy or more would likely result in loss of the hand. A British industrial radiographer who was estimated to have received a hand dose of 100 Gy over the course of his lifetime lost his hand because of radiation dermatitis. Most people become ill after an exposure to 1 Gy or more. Fetuses are often more vulnerable to radiation and may miscarry, especially in the first trimester.

One hour after a surface burst, the radiation from fallout in the crater region is 30 grays per hour (Gy/h). Civilian dose rates in peacetime range from 30 to 100 μGy per year.

Fallout radiation decays relatively quickly with time. Most areas become fairly safe for travel and decontamination after three to five weeks.

For yields of up to 10 kt, prompt radiation is the dominant producer of casualties on the battlefield. Humans receiving an acute incapacitating dose (30 Gy) have their performance degraded almost immediately and become ineffective within several hours. However, they do not die until five to six days after exposure, assuming they do not receive any other injuries. Individuals receiving less than a total of 1.5 Gy are not incapacitated. People receiving doses greater than 1.5 Gy become disabled, and some eventually die.

A dose of 5.3 Gy to 8.3 Gy is considered lethal but not immediately incapacitating. Personnel exposed to this amount of radiation have their cognitive performance degraded in two to three hours, depending on how physically demanding the tasks they must perform are, and remain in this disabled state at least two days. However, at that point they experience a recovery period and can perform non-demanding tasks for about six days, after which they relapse for about four weeks. At this time they begin exhibiting symptoms of radiation poisoning of sufficient severity to render them totally ineffective. Death follows at approximately six weeks after exposure, although outcomes may vary.

Long term

Late or delayed effects of radiation occur following a wide range of doses and dose rates. Delayed effects may appear months to years after irradiation and include a wide variety of effects involving almost all tissues or organs. Some of the possible delayed consequences of radiation injury, with the rates above the background prevalence, depending on the absorbed dose, include carcinogenesis, cataract formation, chronic radiodermatitis, decreased fertility, and genetic mutations.

Presently, the only teratological effect observed in humans following nuclear attacks on highly populated areas is microcephaly which is the only proven malformation, or congenital abnormality, found in the in utero developing human fetuses present during the Hiroshima and Nagasaki bombings. Of all the pregnant women who were close enough to be exposed to the prompt burst of intense neutron and gamma doses in the two cities, the total number of children born with microcephaly was below 50. No statistically demonstrable increase of congenital malformations was found among the later conceived children born to survivors of the nuclear detonations at Hiroshima and Nagasaki. The surviving women of Hiroshima and Nagasaki who could conceive and were exposed to substantial amounts of radiation went on and had children with no higher incidence of abnormalities than the Japanese average.

The Baby Tooth Survey founded by the husband and wife team of physicians Eric Reiss and Louise Reiss, was a research effort focused on detecting the presence of strontium-90, a cancer-causing radioactive isotope created by the more than 400 atomic tests conducted above ground that is absorbed from water and dairy products into the bones and teeth given its chemical similarity to calcium. The team sent collection forms to schools in the St. Louis, Missouri area, hoping to gather 50,000 teeth each year. Ultimately, the project collected over 300,000 teeth from children of various ages before the project was ended in 1970.

Preliminary results of the Baby Tooth Survey were published in the November 24, 1961, edition of the journal Science, and showed that levels of strontium-90 had risen steadily in children born in the 1950s, with those born later showing the most pronounced increases. The results of a more comprehensive study of the elements found in the teeth collected showed that children born after 1963 had levels of strontium-90 in their baby teeth that was 50 times higher than that found in children born before large-scale atomic testing began. The findings helped convince U.S. President John F. Kennedy to sign the Partial Nuclear Test Ban Treaty with the United Kingdom and Soviet Union, which ended the above-ground nuclear weapons testing that created the greatest amounts of atmospheric nuclear fallout.

Some considered the baby tooth survey a "campaign [that] effectively employed a variety of media advocacy strategies" to alarm the public and "galvanized" support against atmospheric nuclear testing,, and putting an end to such testing was commonly viewed as a positive outcome for a myriad of reasons. The survey could not show at the time, nor in the decades that have elapsed, that the levels of global strontium-90 or fallout in general, were life-threatening, primarily because "50 times the strontium-90 from before nuclear testing" is a minuscule number, and multiplication of minuscule numbers results in only a slightly larger minuscule number. Moreover, the Radiation and Public Health Project that currently retains the teeth has had their stance and publications criticized: a 2003 article in The New York Times states that many scientists consider the group's work controversial, with little credibility with the scientific establishment, while some scientists consider it "good, careful work". In an April 2014 article in Popular Science, Sarah Fecht argues that the group's work, specifically the widely discussed case of cherry-picking data to suggest that fallout from the 2011 Fukushima accident caused infant deaths in America, is "junk science", as despite their papers being peer-reviewed, independent attempts to corroborate their results return findings that are not in agreement with what the organization suggests. The organization had earlier suggested the same thing occurred after the 1979 Three Mile Island accident, though the Atomic Energy Commission argued this was unfounded. The tooth survey, and the organization's new target of pushing for test bans with US nuclear electric power stations, is detailed and critically labelled as the "Tooth Fairy issue" by the Nuclear Regulatory Commission.

Effects on the environment
In the event of a large-scale nuclear exchange, the effects would be drastic on the environment as well as directly to the human population. Within direct blast zones everything would be vaporized and destroyed. Cities damaged but not completely destroyed would lose their water system due to the loss of power and supply lines rupturing. Within the local nuclear fallout pattern suburban areas' water supplies would become extremely contaminated. At this point stored water would be the only safe water to use. All surface water within the fallout would be contaminated by falling fission products.

Within the first few months of the nuclear exchange the nuclear fallout will continue to develop and detriment the environment. Dust, smoke, and radioactive particles will fall hundreds of kilometers downwind of the explosion point and pollute surface water supplies. Iodine-131 would be the dominant fission product within the first few weeks, and in the months following the dominant fission product would be strontium-90. These fission products would remain in the fallout dust, resulting in rivers, lakes, sediments, and soils being contaminated with the fallout.

Rural areas' water supplies would be slightly less polluted by fission particles in intermediate and long-term fallout than cities and suburban areas. Without additional contamination, the lakes, reservoirs, rivers, and runoff would be gradually less contaminated as water continued to flow through its system.

Groundwater supplies such as aquifers would however remain unpolluted initially in the event of a nuclear fallout. Over time the groundwater could become contaminated with fallout particles, and would remain contaminated for over 10 years after a nuclear engagement. It would take hundreds or thousands of years for an aquifer to become completely pure. Groundwater would still be safer than surface water supplies and would need to be consumed in smaller doses. Long term, cesium-137 and strontium-90 would be the major radionuclides affecting the fresh water supplies.

The dangers of nuclear fallout do not stop at increased risks of cancer and radiation sickness, but also include the presence of radionuclides in human organs from food. A fallout event would leave fission particles in the soil for animals to consume, followed by humans. Radioactively contaminated milk, meat, fish, vegetables, grains and other food would all be dangerous because of fallout.

From 1945 to 1967 the U.S. conducted hundreds of nuclear weapon tests. Atmospheric testing took place over the US mainland during this time and as a consequence scientists have been able to study the effect of nuclear fallout on the environment. Detonations conducted near the surface of the earth irradiated thousands of tons of soil. Of the material drawn into the atmosphere, portions of radioactive material will be carried by low altitude winds and deposited in surrounding areas as radioactive dust. The material intercepted by high altitude winds will continue to travel. When a radiation cloud at high altitude is exposed to rainfall, the radioactive fallout will contaminate the downwind area below.

Agricultural fields and plants will absorb the contaminated material and animals will consume the radioactive material. As a result, the nuclear fallout may cause livestock to become ill or die, and if consumed the radioactive material will be passed on to humans.

The damage to other living organism as a result to nuclear fallout depends on the species. Mammals particularly are extremely sensitive to nuclear radiation, followed by birds, plants, fish, reptiles, crustaceans, insects, moss, lichen, algae, bacteria, mollusks, and viruses.

Climatologist Alan Robock and atmospheric and oceanic sciences professor Brian Toon created a model of a hypothetical small-scale nuclear war that would have approximately 100 weapons used. In this scenario, the fires would create enough soot into the atmosphere to block sunlight, lowering global temperatures by more than one degree Celsius. The result would have the potential of creating widespread food insecurity (nuclear famine). Precipitation across the globe would be disrupted as a result. If enough soot was introduced in the upper atmosphere the planet's ozone layer could potentially be depleted, affecting plant growth and human health.

Radiation from the fallout would linger in soil, plants, and food chains for years. Marine food chains are more vulnerable to the nuclear fallout and the effects of soot in the atmosphere.

Fallout radionuclides' detriment in the human food chain is apparent in the lichen-caribou-eskimo studies in Alaska. The primary effect on humans observed was thyroid dysfunction. The result of a nuclear fallout is incredibly detrimental to human survival and the biosphere. Fallout alters the quality of our atmosphere, soil, and water and causes species to go extinct.

Fallout protection

During the Cold War, the governments of the U.S., the USSR, Great Britain, and China attempted to educate their citizens about surviving a nuclear attack by providing procedures on minimizing short-term exposure to fallout. This effort commonly became known as Civil Defense.

Fallout protection is almost exclusively concerned with protection from radiation. Radiation from a fallout is encountered in the forms of alpha, beta, and gamma radiation, and as ordinary clothing affords protection from alpha and beta radiation, most fallout protection measures deal with reducing exposure to gamma radiation. For the purposes of radiation shielding, many materials have a characteristic halving thickness: the thickness of a layer of a material sufficient to reduce gamma radiation exposure by 50%. Halving thicknesses of common materials include: 1 cm (0.4 inch) of lead, 6 cm (2.4 inches) of concrete, 9 cm (3.6 inches) of packed earth or 150 m (500 ft) of air. When multiple thicknesses are built, the shielding multiplies. A practical fallout shield is ten halving-thicknesses of a given material, such as 90 cm (36 inches) of packed earth, which reduces gamma ray exposure by approximately 1024 times (210). A shelter built with these materials for the purposes of fallout protection is known as a fallout shelter.

Personal protective equipment
As the nuclear energy sector continues to grow, the international rhetoric surrounding nuclear warfare intensifies, and the ever-present threat of radioactive materials falling into the hands of dangerous people persists, many scientists are working hard to find the best way to protect human organs from the harmful effects of high energy radiation. Acute radiation syndrome (ARS) is the most immediate risk to humans when exposed to ionizing radiation in dosages greater than around 0.1 Gy/hr. Radiation in the low energy spectrum (alpha and beta radiation) with minimal penetrating power is unlikely to cause significant damage to internal organs. The high penetrating power of gamma and neutron radiation, however, easily penetrates the skin and many thin shielding mechanisms to cause cellular degeneration in the stem cells found in bone marrow. While full body shielding in a secure fallout shelter as described above is the most optimal form of radiation protection, it requires being locked in a very thick bunker for a significant amount of time. In the event of a nuclear catastrophe of any kind, it is imperative to have mobile protection equipment for medical and security personnel to perform necessary containment, evacuation, and any number of other important public safety objectives. The mass of the shielding material required to properly protect the entire body from high energy radiation would make functional movement essentially impossible. This has led scientists to begin researching the idea of partial body protection: a strategy inspired by hematopoietic stem cell transplantation (HSCT). The idea is to use enough shielding material to sufficiently protect the high concentration of bone marrow in the pelvic region, which contains enough regenerative stem cells to repopulate the body with unaffected bone marrow. More information on bone marrow shielding can be found in the Health Physics Radiation Safety Journal article Selective Shielding of Bone Marrow: An Approach to Protecting Humans from External Gamma Radiation, or in the Organisation for Economic Co-operation and Development (OECD) and the Nuclear Energy Agency (NEA)'s 2015 report: Occupational Radiation Protection in Severe Accident Management.

The seven-ten rule
The danger of radiation from fallout also decreases rapidly with time due in large part to the exponential decay of the individual radionuclides. A book by Cresson H. Kearny presents data showing that for the first few days after the explosion, the radiation dose rate is reduced by a factor of ten for every seven-fold increase in the number of hours since the explosion. He presents data showing that "it takes about seven times as long for the dose rate to decay from 1000 roentgens per hour (1000 R/hr) to 10 R/hr (48 hours) as to decay from 1000 R/hr to 100 R/hr (7 hours)." This is a rule of thumb based on observed data, not a precise relation.

United States government guides for fallout protection
The United States government, often the Office of Civil Defense in the Department of Defense, provided guides to fallout protection in the 1960s, frequently in the form of booklets. These booklets provided information on how to best survive nuclear fallout. They also included instructions for various fallout shelters, whether for a family, a hospital, or a school shelter were provided. There were also instructions for how to create an improvised fallout shelter, and what to do to best increase a person's chances for survival if they were unprepared.

The central idea in these guides is that materials like concrete, dirt, and sand are necessary to shield a person from fallout particles and radiation. A significant amount of materials of this type are necessary to protect a person from fallout radiation, so safety clothing cannot protect a person from fallout radiation. However, protective clothing can keep fallout particles off a person's body, but the radiation from these particles will still permeate through the clothing. For safety clothing to be able to block the fallout radiation, it would have to be so thick and heavy that a person could not function.

These guides indicated that fallout shelters should contain enough resources to keep its occupants alive for up to two weeks. Community shelters were preferred over single-family shelters. The more people in a shelter, the greater quantity and variety of resources that shelter would be equipped with. These communities’ shelters would also help facilitate efforts to recuperate the community in the future. Single family shelters should be built below ground if possible. Many different types of fallout shelters could be made for a relatively small amount of money. A common format for fallout shelters was to build the shelter underground, with solid concrete blocks to act as the roof. If a shelter could only be partially underground, it was recommended to mound over that shelter with as much dirt as possible. If a house had a basement, it is best for a fallout shelter to be constructed in a corner of the basement. The center of a basement is where the most radiation will be because the easiest way for radiation to enter a basement is from the floor above. The two of the walls of the shelter in a basement corner will be the basement walls that are surrounded by dirt outside. Cinder blocks filled with sand or dirt were highly recommended for the other two walls. Concrete blocks, or some other dense material, should be used as a roof for a basement fallout shelter because the floor of a house is not an adequate roof for a fallout shelter. These shelters should contain water, food, tools, and a method for dealing with human waste.

If a person did not have a shelter previously built, these guides recommended trying to get underground. If a person had a basement but no shelter, they should put food, water, and a waste container in the corner of the basement. Then items such as furniture should be piled up to create walls around the person in the corner. If the underground cannot be reached, a tall apartment building at least ten miles from the blast was recommended as a good fallout shelter. People in these buildings should get as close to the center of the building as possible and avoid the top and ground floors.

Schools were preferred fallout shelters according to the Office of Civil Defense. Schools, not including universities, contained one-quarter of the population of the United States when they were in session at that time. Schools distribution across the nation reflected the density of the population and were often a best building in a community to act as a fallout shelter. Schools also already had organization with leaders set in place. The Office of Civil Defense recommended altering current schools and the construction of future schools to include thicker walls and roofs, better protected electrical systems, a purifying ventilation system, and a protected water pump. The Office of Civil Defense determined 10 square feet of net area per person were necessary in schools that were to function as a fallout shelter. A normal classroom could provide 180 people with area to sleep. If an attack were to happen, all the unnecessary furniture was to be moved out of the classrooms to make more room for people. It was recommended to keep one or two tables in the room if possible to use as a food-serving station.

The Office of Civil Defense conducted four case studies to find the cost of turning four standing schools into fallout shelters and what their capacity would be. The cost of the schools per occupant in the 1960s were $66.00, $127.00, $50.00, and $180.00. The capacity of people these schools could house as shelters were 735, 511, 484, and 460 respectively.

The US Department of Homeland Security and the Federal Emergency Management Agency in coordination with other agencies concerned with public protection in the aftermath of a nuclear detonation have developed more recent guidance documents that build on the older Civil Defense frameworks. Planning Guidance for Response to a Nuclear Detonation was published in 2022 and provided in-depth analysis and response planning for local government jurisdictions.

Nuclear reactor accident
Fallout can also refer to nuclear accidents, although a nuclear reactor does not explode like a nuclear weapon. The isotopic signature of bomb fallout is very different from the fallout from a serious power reactor accident (such as Chernobyl or Fukushima).

The key differences are in volatility and half-life.

Volatility
The boiling point of an element (or its compounds) is able to control the percentage of that element that a power reactor accident releases. The ability of an element to form a solid controls the rate it is deposited on the ground after having been injected into the atmosphere by a nuclear detonation or accident.

Half-life
A half life is the time it takes half of the radiation of a specific substance to decay. A large amount of short-lived isotopes such as 97Zr are present in bomb fallout. This isotope and other short-lived isotopes are constantly generated in a power reactor, but because the criticality occurs over a long length of time, the majority of these short lived isotopes decay before they can be released.

Preventive measures
Nuclear fallout can occur due to a number of different sources. One of the most common potential sources of nuclear fallout is that of nuclear reactors. Because of this, steps must be taken to ensure the risk of nuclear fallout at nuclear reactors is controlled. In the 1950s and 60's, the United States Atomic Energy Commission (AEC) began developing safety regulations against nuclear fallout for civilian nuclear reactors. Because the effects of nuclear fallout are more widespread and longer lasting than other forms of energy production accidents, the AEC desired a more proactive response towards potential accidents than ever before. One step to prevent nuclear reactor accidents was the Price-Anderson Act. Passed by Congress in 1957, the Price-Anderson Act ensured government assistance above the $60 million covered by private insurance companies in the case of a nuclear reactor accident. The main goal of the Price-Anderson Act was to protect the multi-billion-dollar companies overseeing the production of nuclear reactors. Without this protection, the nuclear reactor industry could potentially come to a halt, and the protective measures against nuclear fallout would be reduced. However, because of the limited experience in nuclear reactor technology, engineers had a difficult time calculating the potential risk of released radiation. Engineers were forced to imagine every unlikely accident, and the potential fallout associated with each accident. The AEC's regulations against potential nuclear reactor fallout were centered on the ability of the power plant to the Maximum Credible Accident (MCA). The MCA involved a "large release of radioactive isotopes after a substantial meltdown of the reactor fuel when the reactor coolant system failed through a Loss-of-Coolant Accident". The prevention of the MCA enabled a number of new nuclear fallout preventive measures. Static safety systems, or systems without power sources or user input, were enabled to prevent potential human error. Containment buildings, for example, were reliably effective at containing a release of radiation and did not need to be powered or turned on to operate. Active protective systems, although far less dependable, can do many things that static systems cannot. For example, a system to replace the escaping steam of a cooling system with cooling water could prevent reactor fuel from melting. However, this system would need a sensor to detect the presence of releasing steam. Sensors can fail, and the results of a lack of preventive measures would result in a local nuclear fallout. The AEC had to choose, then, between active and static systems to protect the public from nuclear fallout. With a lack of set standards and probabilistic calculations, the AEC and the industry became divided on the best safety precautions to use. This division gave rise to the Nuclear Regulatory Commission (NRC). The NRC was committed to 'regulations through research', which gave the regulatory committee a knowledge bank of research on which to draw their regulations. Much of the research done by the NRC sought to move safety systems from a deterministic viewpoint into a new probabilistic approach. The deterministic approach sought to foresee all problems before they arose. The probabilistic approach uses a more mathematical approach to weigh the risks of potential radiation leaks. Much of the probabilistic safety approach can be drawn from the radiative transfer theory in Physics, which describes how radiation travels in free space and through barriers. Today, the NRC is still the leading regulatory committee on nuclear reactor power plants.

Determining extent of nuclear fallout
The International Nuclear and Radiological Event Scale (INES) is the primary form of categorizing the potential health and environmental effects of a nuclear or radiological event and communicating it to the public. The scale, which was developed in 1990 by the International Atomic Energy Agency and the Nuclear Energy Agency of the Organization for Economic Co-operation and Development, classifies these nuclear accidents based on the potential impact of the fallout:

 * Defence-in-Depth: This is the lowest form of nuclear accidents and refers to events that have no direct impact on people or the environment but must be taken note of to improve future safety measures.
 * Radiological Barriers and Control: This category refers to events that have no direct impact on people or the environment and only refer to the damage caused within major facilities.
 * People and the Environment: This section of the scale consists of more serious nuclear accidents. Events in this category could potentially cause radiation to spread to people close to the location of the accident. This also includes an unplanned, widespread release of the radioactive material.

The INES scale is composed of seven steps that categorize the nuclear events, ranging from anomalies that must be recorded to improve upon safety measures to serious accidents that require immediate action.

Chernobyl

The 1986 nuclear reactor explosion at Chernobyl was categorized as a Level 7 accident, which is the highest possible ranking on the INES scale, due to widespread environmental and health effects and "external release of a significant fraction of reactor core inventory". The nuclear accident still stands as the only accident in commercial nuclear power that led to radiation-related deaths. The steam explosion and fires released approximately 5200 PBq, or at least 5 percent of the reactor core, into the atmosphere. The explosion itself resulted in the deaths of two plant workers, while 28 people died over the weeks that followed of severe radiation poisoning. Furthermore, young children and adolescents in the areas most contaminated by the radiation exposure showed an increase in the risk for thyroid cancer, although the United Nations Scientific Committee on the Effects of Atomic Radiation stated that "there is no evidence of a major public health impact" apart from that. The nuclear accident also took a heavy toll on the environment, including contamination in urban environments caused by the deposition of radionuclides and the contamination of "different crop types, in particular, green leafy vegetables ... depending on the deposition levels, and time of the growing season".

Three Mile Island

The nuclear meltdown at Three Mile Island in 1979 was categorized as a Level 5 accident on the INES scale because of the "severe damage to the reactor core" and the radiation leak caused by the incident. Three Mile Island was the most serious accident in the history of American commercial nuclear power plants, yet the effects were different from those of the Chernobyl accident. A study done by the Nuclear Regulatory Commission following the incident reveals that the nearly 2 million people surrounding the Three Mile Island plant "are estimated to have received an average radiation dose of only 1 millirem above the usual background dose". Furthermore, unlike those affected by radiation in the Chernobyl accident, the development of thyroid cancer in the people around Three Mile Island was "less aggressive and less advanced".

Fukushima Like the Three Mile Island incident, the incident at Fukushima was initially categorized as a Level 5 accident on the INES scale after a tsunami disabled the power supply and cooling of three reactors, which then suffered significant melting in the days that followed. However, after combining the events at the three reactors rather than assessing them individually, the accident was upgraded to an INES Level 7. The radiation exposure from the incident caused a recommended evacuation for inhabitants up to 30 km away from the plant. However, it was also hard to track such exposure because 23 out of the 24 radioactive monitoring stations were also disabled by the tsunami. Removing contaminated water, both in the plant itself and run-off water that spread into the sea and nearby areas, became a huge challenge for the Japanese government and plant workers. During the containment period following the accident, thousands of cubic meters of slightly contaminated water were released in the sea to free up storage for more contaminated water in the reactor and turbine buildings. However, the fallout from the Fukushima accident had a minimal impact on the surrounding population. According to the Institut de Radioprotection et de Surêté Nucléaire, over 62 percent of assessed residents within the Fukushima prefecture received external doses of less than 1 mSv in the four months following the accident. In addition, comparing screening campaigns for children inside the Fukushima prefecture and in the rest of the country revealed no significant difference in the risk of thyroid cancer.

International nuclear safety standards
Founded in 1974, the International Atomic Energy Agency (IAEA) was created to set forth international standards for nuclear reactor safety. However, without a proper policing force, the guidelines set forth by the IAEA were often treated lightly or ignored completely. In 1986, the disaster at Chernobyl was evidence that international nuclear reactor safety was not to be taken lightly. Even in the midst of the Cold War, the Nuclear Regulatory Commission sought to improve the safety of Soviet nuclear reactors. As noted by IAEA Director General Hans Blix, "A radiation cloud doesn't know international boundaries." The NRC showed the Soviets the safety guidelines used in the US: capable regulation, safety-minded operations, and effective plant designs. The Soviets, however, had their own priority: keeping the plant running at all costs. In the end, the same shift between deterministic safety designs to probabilistic safety designs prevailed. In 1989, the World Association of Nuclear Operators (WANO) was formed to cooperate with the IAEA to ensure the same three pillars of reactor safety across international borders. In 1991, WANO concluded (using a probabilistic safety approach) that all former communist-controlled nuclear reactors could not be trusted, and should be closed. Compared to a "Nuclear Marshall Plan", efforts were taken throughout the 1990s and 2000s to ensure international standards of safety for all nuclear reactors.

title: Nuclear fallout


text:
Talk:Eiffel

The tower is never just called "Eiffel" and is therefore not a valid entry in a disambiguation page. In addition, Eiffel programming language and especially Gustave Eiffel are boderline: Do to the fact that this programing language is not at all widely known (unlike, say Java) the words "programming language" are almost allways going to follow this usage. Furthermore, people are only commonly referred to by only their last name in the military or in certain special exceptions (like Seneca or Cicero). In cases like these I tend to simply redirect the nominally ambiguous term to the most widely known and used usage (in this case Gustave Eiffel). I will leave this one alone though -- mainly as an example of disambiguation gone bad. --maveric149 02:44, 27 May 2002

Well, I've typed in "Eiffel" to get the programming language and then later on to get the guy's name so obviously people will try it. Also, it doesn't make that much sence to not list the tower since it's named after the guy and is what he's most well known for. If you're looking for the maker of the Eiffel tower you're probably not going to know the guy's full name so he needs to be listed, the area in Germany needs to be listed since it's a common misspelling, and the language should be listed because someone who doesn't know Wikipedia that well won't know to type "Eiffel programming langauge" and anyways there are many programming language articles that don't contain the phrase "programming langauge" in the title so it's quite concievable that "Eiffel" would go to the language. As for the techno group, who knows maybe they don't know the ending numbers so Eiffel makes sence as a search there. This is a perfectly fine disambiguation page that makes perfect sence the way it is. - DNewhall 19:51, 10 August 2005

DNewhall, I agree! This is perfectly userfriendly and okay. 193.135.25.34 14:22, 7 March 2007 (UTC)

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

title: Talk:Eiffel


text:
Archimedes' screw

The Archimedes' screw, also known as the Archimedean screw, hydrodynamic screw, water screw or Egyptian screw, is one of the earliest hydraulic machines. Using Archimedes screws as water pumps (Archimedes screw pump (ASP) or screw pump ) dates back many centuries. As a machine used for lifting water from a low-lying body of water into irrigation ditches, water is lifted by turning a screw-shaped surface inside a pipe. In the modern world, Archimedes screw pumps are widely used in wastewater treatment plants and for dewatering low-lying regions. Run in reverse, Archimedes screw turbines act as a new form of small hydroelectric powerplant that can be applied even in low head sites. Such generators operate in a wide range of flows (0.01 $$m^3/s$$ to 14.5 $$m^3/s$$) and heads (0.1 m to 10 m), including low heads and moderate flow rates that is not ideal for traditional turbines and not occupied by high performance technologies. The Archimedes screw is a reversible hydraulic machine, and there are several examples of Archimedes screw installations where the screw can operate at different times as either pump or generator, depending on needs for power and watercourse flow.

Archimedes screw is named after Greek mathematician Archimedes who first described it around 234 BC, although the device had been used in Ancient Egypt long before his time. A screw conveyor is a similar device which transports bulk materials such as powders and grains.

History
The screw pump is the oldest positive displacement pump. The first records of a water screw, or screw pump, date back to Hellenistic Egypt before the 3rd century BC. The Egyptian screw, used to lift water from the Nile, was composed of tubes wound round a cylinder; as the entire unit rotates, water is lifted within the spiral tube to the higher elevation. A later screw pump design from Egypt had a spiral groove cut on the outside of a solid wooden cylinder and then the cylinder was covered by boards or sheets of metal closely covering the surfaces between the grooves.

Some researchers have proposed this device was used to irrigate the Hanging Gardens of Babylon, one of the Seven Wonders of the Ancient World. A cuneiform inscription of Assyrian King Sennacherib (704–681 BC) has been interpreted by Stephanie Dalley to describe casting water screws in bronze some 350 years earlier. This is consistent with classical author Strabo, who describes the Hanging Gardens as irrigated by screws.

The screw pump was later introduced from Egypt to Greece. It was described by Archimedes, on the occasion of his visit to Egypt, circa 234 BC. This tradition may reflect only that the apparatus was unknown to the Greeks before Hellenistic times. Archimedes never claimed credit for its invention, but it was attributed to him 200 years later by Diodorus, who believed that Archimedes invented the screw pump in Egypt. Depictions of Greek and Roman water screws show them being powered by a human treading on the outer casing to turn the entire apparatus as one piece, which would require that the casing be rigidly attached to the screw.

German engineer Konrad Kyeser equipped the Archimedes screw with a crank mechanism in his Bellifortis (1405). This mechanism quickly replaced the ancient practice of working the pipe by treading.

Design
The Archimedes screw consists of a screw (a helical surface surrounding a central cylindrical shaft) inside a hollow pipe. The screw is usually turned by windmill, manual labor, cattle, or by modern means, such as a motor. As the shaft turns, the bottom end scoops up a volume of water. This water is then pushed up the tube by the rotating helicoid until it pours out from the top of the tube.

The contact surface between the screw and the pipe does not need to be perfectly watertight, as long as the amount of water being scooped with each turn is large compared to the amount of water leaking out of each section of the screw per turn. If water from one section leaks into the next lower one, it will be transferred upwards by the next segment of the screw.

In some designs, the screw is fused to the casing and they both rotate together, instead of the screw turning within a stationary casing. The screw could be sealed to the casing with pitch resin or other adhesive, or the screw and casing could be cast together as a single piece in bronze.

The design of the everyday Greek and Roman water screw, in contrast to the heavy bronze device of Sennacherib, with its problematic drive chains, has a powerful simplicity. A double or triple helix was built of wood strips (or occasionally bronze sheeting) around a heavy wooden pole. A cylinder was built around the helices using long, narrow boards fastened to their periphery and waterproofed with pitch.

Studies show that the volume of flow passes through Archimedes screws is a function of inlet depth, diameter and rotation speed of the screw. Therefore, the following analytical equation could be used to design Archimedes screws:

$$D_O =\sqrt[3]{\frac{16\pi Q}{\sigma\omega (2\theta_O-sin2\theta_O-\delta^2(2\theta_i-sin(2\theta_i))}}$$

where $$D_O$$ is in $$(m)$$ and:

$$\omega$$: Rotation speed of the Archimedes screw (rad/s)

$$Q$$: Volumetric flow rate $$(m^3/s)$$

Based on the common standards that the Archimedes screw designers use this analytical equation could be simplified as:

$$D_O\approx \eta Q^{3/7}$$

The value of η could simply determinate using the $$\eta$$ graph or $$\Theta$$ graph. By determination of $$D_O$$, other design parameters of Archimedes screws can be calculated using a step-by-step analytical method.

Uses
The screw was used predominantly for the transport of water to irrigation systems and for dewatering mines or other low-lying areas. It was used for draining land that was underneath the sea in the Netherlands and other places in the creation of polders.

Archimedes screws are used in sewage treatment plants because they cope well with varying rates of flow and with suspended solids. An auger in a snow blower or grain elevator is essentially an Archimedes screw. Concrete mixer trucks use Archimedes screws on the inside of their drum to mix or unload material.

The principle is also found in escalators, which are Archimedes screws designed to lift fish safely from ponds and transport them to another location. This technology is used primarily at fish hatcheries, where it is desirable to minimize the physical handling of fish.

An Archimedes screw was used in the successful 2001 stabilization of the Leaning Tower of Pisa. Small amounts of subsoil saturated by groundwater were removed from far below the north side of the tower, and the weight of the tower itself corrected the lean. Archimedes screws are also used in chocolate fountains.

Screw turbines (ASTs) are a new form of generator for small hydroelectric powerplants that could be applied even in low-head sites. The low rotation speed of ASTs reduces negative impacts on aquatic life and fish.

Variants
A screw conveyor is an Archimedes screw contained within a tube and turned by a motor so as to deliver material from one end of the conveyor to the other. It is particularly suitable for transport of granular materials such as plastic granules used in injection moulding, and cereal grains. It may also be used to transport liquids. In industrial control applications the conveyor may be used as a rotary feeder or variable rate feeder to deliver a measured rate or quantity of material into a process.

A variant of the Archimedes screw can also be found in some injection moulding machines, die casting machines and extrusion of plastics, which employ a screw of decreasing pitch to compress and melt the material. It is also used in a rotary-screw air compressor. On a much larger scale, Archimedes's screws of decreasing pitch are used for the compaction of waste material.

Reverse action
If water is fed into the top of an Archimedes screw, it will force the screw to rotate. The rotating shaft can then be used to drive an electric generator. Such an installation has the same benefits as using the screw for pumping: the ability to handle very dirty water and widely varying rates of flow at high efficiency. Settle Hydro and Torrs Hydro are two reverse screw micro hydro schemes operating in England. The screw works well as a generator at low heads, commonly found in English rivers, including the Thames, powering Windsor Castle.

In 2017, the first reverse screw hydropower in the United States opened in Meriden, Connecticut. The Meriden project was built and is operated by New England Hydropower having a nameplate capacity of 193 kW and a capacity factor of approximately 55% over a 5-year running period.

title: Archimedes' screw


text:
Title 47 of the Code of Federal Regulations

The Code of Federal Regulations, Telecommunications, containing the U.S. federal regulations for telecommunications can be found under Title 47 of the United States Code of Federal Regulations.

Commonly referenced parts

 * Part 15—concerning unlicensed broadcasts and spurious emissions
 * Part 18—concerning industrial, scientific, and medical (ISM) radio bands
 * Part 68—concerning direct connection of all terminal equipment to the public switched telephone network
 * Part 73—Radio Broadcast Services
 * Part 74—Remote Broadcast Pickup
 * Part 80—Maritime Service
 * Part 87—concerning aviation services
 * Part 90—concerning licensed wireless communications for businesses and non-federal governments
 * Part 95—concerning GMRS, FRS, MURS, and CB radio
 * Part 97—concerning amateur radio


text:
Physical Quality of Life Index

The Physical Quality of Life Index (PQLI) is an attempt to measure the quality of life or well-being of a country. The value is the average of three statistics: basic literacy rate, infant mortality, and life expectancy at age one, all equally weighted on a 1 to 100 scale.

It was developed for the Overseas Development Council in the mid-1970s by M.D Morris, as one of a number of measures created due to dissatisfaction with the use of GNP as an indicator of development. He thought that they would cover a wide range of indicators like health, sanitation, drinking water, nutrition, education etc. PQLI might be regarded as an improvement but shares the general problems of measuring quality of life in a quantitative way. It has also been criticized because there is a considerable overlap between infant mortality and life expectancy.

The UN Human Development Index is a more widely used means of measuring well-being.

Steps to Calculate Physical Quality of Life:

 * 1) Find percentage of the population that is literate (literacy rate).
 * 2) Find the infant mortality rate. (out of 1000 births)
 * INDEXED Infant Mortality Rate = (166 - infant mortality) × 0.625
 * 1) Find the Life Expectancy.
 * INDEXED Life Expectancy = (Life expectancy - 42) × 2.7
 * 1) Calculate Physical Quality of Life
 * Physical Quality of Life equals the average of Literacy Rate, INDEXED Infant Mortality Rate and INDEXED Life Expectancy.

Increase in national income and per capita income are not the real indicators of economic development, as it has a number of limitations. Increasing incomes of the country are concentrated in the hands of a few people, which is not development. The development of a country should be such that the living standards of the poor rises, and the basic requirements of the citizens are fulfilled. Keeping this in mind, Morris Davis Morris presented the physical quality of life index, in short known as the PQLI. In this index, betterment of physical quality of life of human beings is considered economic development. The level of physical quality of life determines the level of economic development. If any country's physical quality of life is higher than that of the other country, then that country is considered as more developed. There are three standards to measure the physical quality, which are depicted here: 1)- Extent of Education, 2)- Life Expectancy & 3)- Infant Mortality Rate

title: Physical Quality of Life Index


text:
Payola

Payola, in the music industry, is the illegal practice of paying a commercial radio station to play a song without the station disclosing the payment. Under U.S. law, a radio station must disclose songs they were paid to play on the air as sponsored airtime. The number of times the songs are played can influence the perceived popularity of a song, and payola may be used to influence these meters. The Federal Communications Commission (FCC) treats payola as a violation of the Sponsorship Identification Rules, which requires any broadcast of paid material to include a disclosure.

The term payola is a combination of "pay" and "-ola", the latter of which is a suffix of product names common in the early 20th century, such as Pianola, Victrola, Amberola, Mazola, Crayola, Rock-Ola, Shinola, or brands such as the radio equipment manufacturer Motorola.

History
Prior to the 1930s, there was little public scrutiny of the reasoning behind a song's popularity. The advertising agencies which sponsored NBC's radio/TV show Your Hit Parade refused to reveal the specific methods that were used to determine top hits. Only general and vague statements were offered; that determining top hits was based on "readings of radio requests, sheet music sales, dance hall favorites and jukebox tabulations". Early attempts to stop payola were met with silence by publishers.

Prosecution for payola in the 1950s was in part a reaction of the traditional music establishment against newcomers. The emergence of hit radio had become a threat to the wages of song-pluggers and publisher's revenue streams. By the mid-1940s, three-quarters of the records produced in the United States went into jukeboxes. Attempts were made to link all payola to rock-and-roll music. In the 1950s, independent record companies or music publishers frequently used payola to promote rock and roll on American radio.

While the amount of money involved remains largely unpublished, Phil Lind of Chicago's WAIT disclosed in Congressional hearings that he had taken US$22,000 to play a record.

U.S. investigations and aftermath
The first U.S. Congressional Payola Investigations occurred in 1959, carried out by the House Subcommittee on Legislative Oversight into payola, and prompted by a parallel investigation in the US Senate.

DJ Alan Freed, who was uncooperative in committee hearings, was fired as a result. Dick Clark also testified before the committee, but avoided repercussions, partially due to the fact that he had divested his ownership interest in music-industry holdings.

Following the investigation, radio DJs were stripped of the authority to make programming decisions and payola became a misdemeanor offense. Programming decisions became the responsibility of station program directors. However, this had the result of simplifying the process of payola: instead of reaching numerous DJs, record labels only had to persuade the station's program director. Labels could circumvent payola allegations by utilizing independent third parties (see below).

In 1976, inner-city urban soul DJ Frankie Crocker was indicted in a payola scandal, causing him to leave New York radio, where his influence was greatest. The charges were later dropped and he returned to New York, hosting MTV's video jukebox.

Following the creation of music sharing websites in the late 1990s, the power of independent promoters declined and labels returned to dealing with stations directly.

Modus operandi
Payola is used by record labels to promote their artists, and can be in the form of monetary rewards or other types of reimbursement. This can include purchasing advertising, requiring bands to play station-sponsored concerts, or paying stations to hold "meet the band" contests. In exchange, the band gains a place on a station's playlist or a lesser-known band of the label may gain air time.

Third-party loophole
A loophole in U.S. payola laws is for labels to utilize a third-party or independent promoter (not to be confused with independent record label). The promoter would offer "promotion payments" to station directors for putting their client's artists on the station's playlist, sidestepping Federal Communications Commission (FCC) regulations. As it was seen as falling outside the payola rules, stations did not deem it necessary to report to authorities. This practice became widespread until a 1986 NBC News investigation called "The New Payola" instigated another round of Congressional investigations.

In 2002, investigations by the office of then-New York District Attorney Eliot Spitzer uncovered evidence that executives at Sony BMG music labels had made deals with several large commercial radio chains. Spitzer's office settled out of court with Sony BMG Music Entertainment in July 2005, Warner Music Group in November 2005 and Universal Music Group in May 2006. The three conglomerates agreed to pay $10 million, $5 million, and $12 million respectively to New York State non-profit organizations that will fund music education and appreciation programs. EMI settled in 2006 for $3.75 million.

Concerns about contemporary forms of payola in the US prompted an investigation during which the FCC established firmly that the "loophole" was still a violation of the law. In 2007, four companies (CBS Radio, Citadel, Clear Channel, and Entercom) settled on paying $12.5 million in fines and accepting tougher restrictions for three years, although no company admitted any wrongdoing. Due to increased legal scrutiny, some larger radio companies (including industry giant Clear Channel) now refuse to have any contact with independent promoters.

Clear Channel Radio, through iHeartRadio, launched a program called On the Verge that required the stations to play a given song at least 150 times in order to give a new artist exposure. Brand managers at the top of the Clear Channel chain, after listening to hundreds of songs and filtering them down to about five or six favorites from various formats, send those selections to program directors across the country. These program directors vote on which ones they think radio listeners will like the most. Songs that benefited with the exposure were Iggy Azalea's "Fancy", Tinashe's "2 On", Anthony Lewis' "Candy Rain", and Jhené Aiko's "The Worst". Tom Poleman, president of national programming platforms for the company, stated that the acts selected are based solely on the quality of their music and not on label pressure.

On Spotify, labels can pay for tracks to appear in user play-lists as "Sponsored Songs". It is possible for users to opt out of this in their account settings.

As money laundering scheme
In Mexico, South America, and some regions along the U.S. southern border, payola is used to launder money from illegal operations. In this practice, unknown "new artists" will suddenly appear on multiple formats and be aggressively promoted by producers of dubious origin, then disappear from the music scene or change their stage name.

Criticism
On 25 September 2007, the U.S. Congress held a hearing on hip hop music entitled From Imus to Industry: The Business of Stereotypes and Degrading Images. In her testimony, Lisa Fager Bediako, co-founder and President of media watchdog group Industry Ears, argued that misogynistic and racist stereotypes permeate hip hop music because record labels, radio stations, and music video channels profit from allowing such material to air while censoring other material. In that context, Fager stated:

"Payola is no longer the local DJ receiving a couple dollars for airplay; it is now an organized corporate crime that supports the lack of balanced content and demeaning imagery with no consequences."

Satire of payola practices
In 1960, Stan Freberg did a parody on the Payola Scandal, by calling it "Old Payola Roll Blues", a two-sided single, where the promoter gets an ordinary teenager, named Clyde Ankle, to record a song, for Obscurity Records, entitled "High School OO OO", and then tries to offer the song to a jazz radio station with phony deals that the disc jockey just won't buy it. It ends with an anti-rock song, saying hello to jazz and swing, and goodbye to amateur nights, including rock and roll.

The Vancouver new wave band the Payola$ chose their moniker during the punk explosion of the late 1970s.

The practice is criticized in the chorus of the Dead Kennedys song "Pull My Strings", a parody of the song "My Sharona" ("My Payola") sung to a crowd of music industry leaders during a music award ceremony.

The They Might Be Giants song "Hey, Mr. DJ, I Thought You Said We Had a Deal" is about the practice. It is narrated from the point of view of a naive and inexperienced musician who has been coerced by a disc jockey into paying for airplay – the disc jockey then disappears and does not deliver on his promise.

The practice is satirized in song "Payola Blues" by Neil Young, from his 1983 album Everybody's Rockin'. It opens by saying "This one's for you, Alan Freed" and then states Cause the things they're doing today would make a saint out of you", implying that Payola corruption is bigger now (or was bigger in the 1980s) than it was in the 1950s.

Payola is referenced in Billy Joel's song "We Didn't Start the Fire", during the verse dealing with the events of 1960.

On a Washington, D.C. radio station in 1999, the disc jockeys announced that they were debuting the Lou Bega song "Mambo Number 5", by saying that they had accepted a large amount of payola to play the song. Ironically, if they had actually been paid to play the song on the air, it would not have been payola, because payola is the unannounced acceptance of a payment to run a song. If the song is identified before being played as being done because the talent or station is being paid to do so, the playing of the song and acceptance of money to do so is perfectly legal, and does not constitute payola.

Payola was depicted in the film The Harder They Come, released in 1972, where a record producer, not the recording artist, controls the airwaves. The portrayal of its protagonist (Jimmy Cliff) as an aspiring musician who is forced to sign away his rights to make a hit record depicts the role of record producers and radio DJs as a dominance – the musician ends up with no aspirations or living the same lifestyle, as in the case of the film Rockers.

In an installment of Mathnet from PBS's Square One Television, the detectives George Frankly and Pat Tuesday investigated a case of suspected payola by forming a fictitious group called "The Googols" and creating their own song titled "Without Math". Payola was eventually ruled out as a cause of increased sales of particular songs at a company.

Criticism of U.S. laws
The FCC and the Communications Act of 1934 both have strict requirements and rules regarding payola. These demand that:"employees of broadcast stations, program producers, program suppliers and others who, in exchange for airing material, have accepted or agreed to receive payments, services or other valuable consideration must disclose this fact. Disclosure of compensation provides broadcasters the information they need to let their audiences know if the material was paid for, and by whom."

Even with these requirements in place, however, record companies have found loopholes within the phrasing of the regulations to continue the practice. These loopholes have created a situation which isolates independent artists from mainstream media. A current example of this is the lengths that artists Macklemore and Ryan Lewis went to get their music heard. Because Lewis and Macklemore belonged to an independent label, they feared payola laws would interfere with their airtime. So they hired an independent arm of Warner Music Group, the Alternative Distribution Alliance, which assists independent acts to get their music on radio. Zach Quillen, manager of Macklemore and Ryan Lewis, discussed how "they paid the alliance a flat monthly fee to help promote the album."

One side effect of the vagueness of the law and the creation of the loophole is the expansion of the concept at the hands of online music sharing websites. In 2009, the website Jango created a plan to accept promotion fees legally by disclosing that they are paid to play the songs. "For as little as $30, a band can buy 1,000 plays on the music-streaming service, slotted in between established artists. The artists themselves choose what other music they'd like to be played next to."

title: Payola


text:
Pig iron

Pig iron, also known as crude iron, is an intermediate good used by the iron industry in the production of steel. It is developed by smelting iron ore in a blast furnace. Pig iron has a high carbon content, typically 3.8–4.7%, along with silica and other dross, which makes it brittle and not useful directly as a material except for limited applications.

Etymology
The traditional shape of the molds used for pig iron ingots is a branching structure formed in sand, with many individual ingots at right angles to a central channel or "runner", resembling a litter of piglets being nursed by a sow. When the metal had cooled and hardened, the smaller ingots (the "pigs") were simply broken from the runner (the "sow"), hence the name "pig iron". As pig iron is intended for remelting, the uneven size of the ingots and the inclusion of small amounts of sand are insignificant issues when compared to the ease of casting and handling.

History
Smelting and producing wrought iron were known in ancient Europe and the Middle East, but it was produced in bloomeries by direct reduction. Small prills of pig iron dispersed in slag are produced in all iron furnaces, but the operator of a bloomery had to avoid conditions causing the phase transition of the iron into liquid in the furnace, as the prill globules or any resulting pig iron are not malleable so can't be hammered in a single piece. Alternatively, decarburizing the pig iron into steel was an extremely tedious process using medieval technology, so in Europe before the Middle Ages the prills were discarded with the slag.

The Chinese were making pig iron by the later Zhou dynasty (which ended in 256 BC). Furnaces such as Lapphyttan in Sweden may date back to the 12th century; and some in the County of Mark dating to the 13th century, which is now part of Westphalia, Germany. It remains to be established whether these northern European developments derive from Chinese ones. Wagner has postulated a possible link via Persian contacts with China along the Silk Road and Viking contacts with Persia, but there is a chronological gap between the Viking period and Lapphyttan.

Uses
Traditionally, pig iron was worked into wrought iron in finery forges, later puddling furnaces, and more recently, into steel. In these processes, pig iron is melted and a strong current of air is directed over it while it is stirred or agitated. This causes the dissolved impurities (such as silicon) to be thoroughly oxidized. An intermediate product of puddling is known as refined pig iron, finers metal, or refined iron.

Pig iron can also be used to produce gray iron. This is achieved by remelting pig iron, often along with substantial quantities of steel and scrap iron, removing undesirable contaminants, adding alloys, and adjusting the carbon content. Ductile iron can also be produced using certain high purity grades of pig iron; depending on the grade of ductile iron being produced, the pig irons chosen may be low in the elements silicon, manganese, sulfur and phosphorus. High purity pig iron is used to dilute any elements in a ductile iron charge which may be harmful to the ductile iron process (except carbon).

Modern uses
Pig iron was historically poured directly out of the bottom of the blast furnace through a trough into a ladle car for transfer to the steel mill in mostly liquid form; in this state, the pig iron was referred to as hot metal. The hot metal was then poured into a steelmaking vessel to produce steel, typically an electric arc furnace, induction furnace or basic oxygen furnace, where the excess carbon is burned off and the alloy composition controlled. Earlier processes for this included the finery forge, the puddling furnace, the Bessemer process, and the open hearth furnace.

Modern steel mills and direct-reduction iron plants transfer the molten iron to a ladle for immediate use in the steel making furnaces or cast it into pigs on a pig-casting machine for reuse or resale. Modern pig casting machines produce stick pigs, which break into smaller 4–10 kg piglets at discharge.

title: Pig iron


text:
Division (mathematics)

Division is one of the four basic operations of arithmetic. The other operations are addition, subtraction, and multiplication. What is being divided is called the dividend, which is divided by the divisor, and the result is called the quotient.

At an elementary level the division of two natural numbers is, among other possible interpretations, the process of calculating the number of times one number is contained within another. For example, if 20 apples are divided evenly between 4 people, everyone receives 5 apples (see picture). However, this number of times or the number contained (divisor) need not be integers.

The division with remainder or Euclidean division of two natural numbers provides an integer quotient, which is the number of times the second number is completely contained in the first number, and a remainder, which is the part of the first number that remains, when in the course of computing the quotient, no further full chunk of the size of the second number can be allocated. For example, if 21 apples are divided between 4 people, everyone receives 5 apples again, and 1 apple remains.

For division to always yield one number rather than an integer quotient plus a remainder, the natural numbers must be extended to rational numbers or real numbers. In these enlarged number systems, division is the inverse operation to multiplication, that is $a = c / b$ means $a × b = c$, as long as $b$ is not zero. If $b = 0$, then this is a division by zero, which is not defined. In the 21-apples example, everyone would receive 5 apple and a quarter of an apple, thus avoiding any leftover.

Both forms of division appear in various algebraic structures, different ways of defining mathematical structure. Those in which a Euclidean division (with remainder) is defined are called Euclidean domains and include polynomial rings in one indeterminate (which define multiplication and addition over single-variabled formulas). Those in which a division (with a single result) by all nonzero elements is defined are called fields and division rings. In a ring the elements by which division is always possible are called the units (for example, 1 and −1 in the ring of integers). Another generalization of division to algebraic structures is the quotient group, in which the result of "division" is a group rather than a number.

Introduction
The simplest way of viewing division is in terms of quotition and partition: from the quotition perspective, $lim_{x→0} sin x⁄x = 1.$ means the number of 5s that must be added to get 20. In terms of partition, $20 / 5$ means the size of each of 5 parts into which a set of size 20 is divided. For example, 20 apples divide into five groups of four apples, meaning that "twenty divided by five is equal to four". This is denoted as $20 / 5$, or $20 / 5 = 4$. In the example, 20 is the dividend, 5 is the divisor, and 4 is the quotient.

Unlike the other basic operations, when dividing natural numbers there is sometimes a remainder that will not go evenly into the dividend; for example, $20⁄5 = 4$ leaves a remainder of 1, as 10 is not a multiple of 3. Sometimes this remainder is added to the quotient as a fractional part, so $10 / 3$ is equal to $10 / 3$ or $3 1⁄3$, but in the context of integer division, where numbers have no fractional part, the remainder is kept separately (or exceptionally, discarded or rounded). When the remainder is kept as a fraction, it leads to a rational number. The set of all rational numbers is created by extending the integers with all possible results of divisions of integers.

Unlike multiplication and addition, division is not commutative, meaning that $3.33...$ is not always equal to $a / b$. Division is also not, in general, associative, meaning that when dividing multiple times, the order of division can change the result. For example, $b / a$, but $(24 / 6) / 2 = 2$ (where the use of parentheses indicates that the operations inside parentheses are performed before the operations outside parentheses).

Division is traditionally considered as left-associative. That is, if there are multiple divisions in a row, the order of calculation goes from left to right:
 * $$a / b / c = (a / b) / c = a / (b \times c) \;\ne\; a/(b/c)= (a\times c)/b.$$

Division is right-distributive over addition and subtraction, in the sense that
 * $$\frac{a \pm b}{c} = (a \pm b) / c = (a/c)\pm (b/c) =\frac{a}{c} \pm \frac{b}{c}.$$

This is the same for multiplication, as $$(a + b) \times c = a \times c + b \times c$$. However, division is not left-distributive, as
 * $$\frac{a}{b + c} = a / (b + c) \;\ne\; (a/b) + (a/c) = \frac{ac+ab}{bc}.$$  For example  $$\frac{12}{2+4} = \frac{12}{6} = 2 ,$$ but $$\frac{12}{2} + \frac{12}{4} = 6+3 = 9 .$$

This is unlike the case in multiplication, which is both left-distributive and right-distributive, and thus distributive.

Notation
Division is often shown in algebra and science by placing the dividend over the divisor with a horizontal line, also called a fraction bar, between them. For example, "a divided by b" can be written as:
 * $$\frac ab$$

which can also be read out loud as "divide a by b" or "a over b". A way to express division all on one line is to write the dividend (or numerator), then a slash, then the divisor (or denominator), as follows:
 * $$a/b$$

This is the usual way of specifying division in most computer programming languages, since it can easily be typed as a simple sequence of ASCII characters. (It is also the only notation used for quotient objects in abstract algebra.) Some mathematical software, such as MATLAB and GNU Octave, allows the operands to be written in the reverse order by using the backslash as the division operator:
 * $$b\backslash a$$

A typographical variation halfway between these two forms uses a solidus (fraction slash), but elevates the dividend and lowers the divisor:
 * $${}^{a}\!/{}_{b}$$

Any of these forms can be used to display a fraction. A fraction is a division expression where both dividend and divisor are integers (typically called the numerator and denominator), and there is no implication that the division must be evaluated further. A second way to show division is to use the division sign (÷, also known as obelus though the term has additional meanings), common in arithmetic, in this manner:
 * $$a \div b$$

This form is infrequent except in elementary arithmetic. ISO 80000-2-9.6 states it should not be used. This division sign is also used alone to represent the division operation itself, as for instance as a label on a key of a calculator. The obelus was introduced by Swiss mathematician Johann Rahn in 1659 in Teutsche Algebra. The ÷ symbol is used to indicate subtraction in some European countries, so its use may be misunderstood.

In some non-English-speaking countries, a colon is used to denote division:

 * $$a : b$$

This notation was introduced by Gottfried Wilhelm Leibniz in his 1684 Acta eruditorum. Leibniz disliked having separate symbols for ratio and division. However, in English usage the colon is restricted to expressing the related concept of ratios.

Since the 19th century, US textbooks have used $$b)a$$ or $$b \overline{)a}$$ to denote a divided by b, especially when discussing long division. The history of this notation is not entirely clear because it evolved over time.

Manual methods
Division is often introduced through the notion of "sharing out" a set of objects, for example a pile of lollies, into a number of equal portions. Distributing the objects several at a time in each round of sharing to each portion leads to the idea of 'chunking' – a form of division where one repeatedly subtracts multiples of the divisor from the dividend itself.

By allowing one to subtract more multiples than what the partial remainder allows at a given stage, more flexible methods, such as the bidirectional variant of chunking, can be developed as well.

More systematically and more efficiently, two integers can be divided with pencil and paper with the method of short division, if the divisor is small, or long division, if the divisor is larger. If the dividend has a fractional part (expressed as a decimal fraction), one can continue the procedure past the ones place as far as desired. If the divisor has a fractional part, one can restate the problem by moving the decimal to the right in both numbers until the divisor has no fraction, which can make the problem easier to solve (e.g., 10/2.5 = 100/25 = 4).

Division can be calculated with an abacus.

Logarithm tables can be used to divide two numbers, by subtracting the two numbers' logarithms, then looking up the antilogarithm of the result.

Division can be calculated with a slide rule by aligning the divisor on the C scale with the dividend on the D scale. The quotient can be found on the D scale where it is aligned with the left index on the C scale. The user is responsible, however, for mentally keeping track of the decimal point.

By computer
Modern calculators and computers compute division either by methods similar to long division, or by faster methods; see Division algorithm.

In modular arithmetic (modulo a prime number) and for real numbers, nonzero numbers have a multiplicative inverse. In these cases, a division by $x$ may be computed as the product by the multiplicative inverse of $x$. This approach is often associated with the faster methods in computer arithmetic.

Euclidean division
Euclidean division is the mathematical formulation of the outcome of the usual process of division of integers. It asserts that, given two integers, a, the dividend, and b, the divisor, such that b ≠ 0, there are unique integers q, the quotient, and r, the remainder, such that a = bq + r and 0 ≤ r < $|b|$, where $|b|$ denotes the absolute value of b.

Of integers
Integers are not closed under division. Apart from division by zero being undefined, the quotient is not an integer unless the dividend is an integer multiple of the divisor. For example, 26 cannot be divided by 11 to give an integer. Such a case uses one of five approaches:
 * 1) Say that 26 cannot be divided by 11; division becomes a partial function.
 * 2) Give an approximate answer as a floating-point number. This is the approach usually taken in numerical computation.
 * 3) Give the answer as a fraction representing a rational number, so the result of the division of 26 by 11 is $$\tfrac{26}{11}$$ (or as a mixed number, so $$\tfrac{26}{11} = 2 \tfrac 4{11}.$$) Usually the resulting fraction should be simplified: the result of the division of 52 by 22 is also $$\tfrac{26}{11}$$. This simplification may be done by factoring out the greatest common divisor.
 * 4) Give the answer as an integer quotient and a remainder, so $$\tfrac{26}{11} = 2 \mbox{ remainder } 4.$$ To make the distinction with the previous case, this division, with two integers as result, is sometimes called Euclidean division, because it is the basis of the Euclidean algorithm.
 * 5) Give the integer quotient as the answer, so $$\tfrac{26}{11} = 2.$$ This is the floor function applied to case 2 or 3. It is sometimes called integer division, and denoted by "//".

Dividing integers in a computer program requires special care. Some programming languages treat integer division as in case 5 above, so the answer is an integer. Other languages, such as MATLAB and every computer algebra system return a rational number as the answer, as in case 3 above. These languages also provide functions to get the results of the other cases, either directly or from the result of case 3.

Names and symbols used for integer division include div, /, \, and %. Definitions vary regarding integer division when the dividend or the divisor is negative: rounding may be toward zero (so called T-division) or toward −∞ (F-division); rarer styles can occur – see modulo operation for the details.

Divisibility rules can sometimes be used to quickly determine whether one integer divides exactly into another.

Of rational numbers
The result of dividing two rational numbers is another rational number when the divisor is not 0. The division of two rational numbers p/q and r/s can be computed as $${p/q \over r/s} = {p \over q} \times {s \over r} = {ps \over qr}.$$

All four quantities are integers, and only p may be 0. This definition ensures that division is the inverse operation of multiplication.

Of real numbers
Division of two real numbers results in another real number (when the divisor is nonzero). It is defined such that a/b = c if and only if a = cb and b ≠ 0.

Of complex numbers
Dividing two complex numbers (when the divisor is nonzero) results in another complex number, which is found using the conjugate of the denominator: $${p+iq \over r+is} = {(p+iq)(r-is) \over (r+is)(r-is)} = {pr+qs + i(qr-ps) \over r^2+s^2} = {pr+qs \over r^2+s^2} + i{qr-ps \over r^2+s^2}.$$

This process of multiplying and dividing by $$r-is$$ is called 'realisation' or (by analogy) rationalisation. All four quantities p, q, r, s are real numbers, and r and s may not both be 0.

Division for complex numbers expressed in polar form is simpler than the definition above: $${p e^{iq} \over r e^{is}} = {p e^{iq} e^{-is} \over r e^{is} e^{-is}} = {p \over r}e^{i(q - s)}. $$

Again all four quantities p, q, r, s are real numbers, and r may not be 0.

Of polynomials
One can define the division operation for polynomials in one variable over a field. Then, as in the case of integers, one has a remainder. See Euclidean division of polynomials, and, for hand-written computation, polynomial long division or synthetic division.

Of matrices
One can define a division operation for matrices. The usual way to do this is to define A / B = AB−1, where B−1 denotes the inverse of B, but it is far more common to write out AB−1 explicitly to avoid confusion. An elementwise division can also be defined in terms of the Hadamard product.

Left and right division
Because matrix multiplication is not commutative, one can also define a left division or so-called backslash-division as A \ B = A−1B. For this to be well defined, B−1 need not exist, however A−1 does need to exist. To avoid confusion, division as defined by A / B = AB−1 is sometimes called right division or slash-division in this context.

With left and right division defined this way, A / (BC) is in general not the same as (A / B) / C, nor is (AB) \ C the same as A \ (B \ C). However, it holds that A / (BC) = (A / C) / B and (AB) \ C = B \ (A \ C).

Pseudoinverse
To avoid problems when A−1 and/or B−1 do not exist, division can also be defined as multiplication by the pseudoinverse. That is, A / B = AB+ and A \ B = A+B, where A+ and B+ denote the pseudoinverses of A and B.

Abstract algebra
In abstract algebra, given a magma with binary operation ∗ (which could nominally be termed multiplication), left division of b by a (written a \ b) is typically defined as the solution x to the equation a ∗ x = b, if this exists and is unique. Similarly, right division of b by a (written b / a) is the solution y to the equation y ∗ a = b. Division in this sense does not require ∗ to have any particular properties (such as commutativity, associativity, or an identity element). A magma for which both a \ b and b / a exist and are unique for all a and all b (the Latin square property) is a quasigroup. In a quasigroup, division in this sense is always possible, even without an identity element and hence without inverses.

"Division" in the sense of "cancellation" can be done in any magma by an element with the cancellation property. Examples include matrix algebras, quaternion algebras, and quasigroups. In an integral domain, where not every element need have an inverse, division by a cancellative element a can still be performed on elements of the form ab or ca by left or right cancellation, respectively. If a ring is finite and every nonzero element is cancellative, then by an application of the pigeonhole principle, every nonzero element of the ring is invertible, and division by any nonzero element is possible. To learn about when algebras (in the technical sense) have a division operation, refer to the page on division algebras. In particular Bott periodicity can be used to show that any real normed division algebra must be isomorphic to either the real numbers R, the complex numbers C, the quaternions H, or the octonions O.

Calculus
The derivative of the quotient of two functions is given by the quotient rule: $${\left(\frac fg\right)}' = \frac{f'g - fg'}{g^2}.$$

Division by zero
Division of any number by zero in most mathematical systems is undefined, because zero multiplied by any finite number always results in a product of zero. Entry of such an expression into most calculators produces an error message. However, in certain higher level mathematics division by zero is possible by the zero ring and algebras such as wheels. In these algebras, the meaning of division is different from traditional definitions.

title: Division (mathematics)