The roentgen equivalent man is an older, CGS unit of equivalent dose, effective dose, committed dose which are measures of the health effect of low levels of ionizing radiation on the human body. Quantities measured in rem are designed to represent the stochastic biological risk of ionizing radiation; these quantities are derived from absorbed dose, which in the CGS system has the unit rad, an older unit. There is no universally applicable conversion constant from rad to rem; the rem has been defined since 1976 as equal to 0.01 sievert, the more used SI unit outside the United States. A number of earlier definitions going back to 1945 were derived from the roentgen unit, named after Wilhelm Röntgen, a German scientist who discovered X-rays; the acronym is now a misleading historical artifact, since 1 roentgen deposits about 0.96 rem in soft biological tissue, when all weighting factors equal unity. Older units of rem following other definitions are up to 17% smaller than the modern rem. One rem carries with it a 0.05% chance of developing cancer.
Doses greater than 100 rem received over a short time period are to cause acute radiation syndrome leading to death within weeks if left untreated. Note that the quantities that are measured in rem were not designed to be correlated to ARS symptoms; the absorbed dose, measured in rad, is the best indicator of ARS. A rem is a large dose of radiation, so the millirem, one thousandth of a rem, is used for the dosages encountered, such as the amount of radiation received from medical x-rays and background sources; the rem and millirem are CGS units in widest use among the US public and government. SI units are the norm outside of the United States, they are encountered within the US in academic and engineering environments; the conventional units for dose rate is mrem/h. Regulatory limits and chronic doses are given in units of mrem/yr or rem/yr, where they are understood to represent the total amount of radiation allowed over the entire year. In many occupational scenarios, the hourly dose rate might fluctuate to levels thousands of times higher for a brief period of time, without infringing on the annual total exposure limits.
There is no exact conversion from hours to years because of leap years, but approximate conversions are: 1 mrem/h = 8766 mrem/yr 0.1141 mrem/h = 1000 mrem/yrThe ICRP once adopted fixed conversion for occupational exposure, although these have not appeared in recent documents: 8 h = 1 day 40 h = 1 week 50 week = 1 yrTherefore, for occupation exposures of that time period, 1 mrem/h = 2000 mrem/yr 0.5 mrem/h = 1000 mrem/yrThe US National Institute of Standards and Technology discourages Americans from expressing doses in rem, in favor of recommending the SI unit. The NIST recommends defining the rem in relation to the SI in every document where this unit is used. For US industries and US firms that do not require the sole use of SI, the unit rem is preferred. Ionizing radiation has stochastic effects on human health; the deterministic effects that can lead to acute radiation syndrome only occur in the case of high doses and high dose rates. A model of deterministic risk would require different weighting factors than are used in the calculation of equivalent and effective dose.
To avoid confusion, deterministic effects are compared to absorbed dose in units of rad, not rem. Stochastic effects are those, such as radiation-induced cancer; the consensus of the nuclear industry, nuclear regulators, governments, is that the incidence of cancers due to ionizing radiation can be modeled as increasing linearly with effective dose at a rate of 0.055% per rem. Individual studies, alternate models, earlier versions of the industry consensus have produced other risk estimates scattered around this consensus model. There is general agreement that the risk is much higher for infants and fetuses than adults, higher for the middle-aged than for seniors, higher for women than for men, though there is no quantitative consensus about this. There is much less data, much more controversy, regarding the possibility of cardiac and teratogenic effects, the modelling of internal dose; the International Commission on Radiological Protection recommends limiting artificial irradiation of the public to an average of 100 mrem of effective dose per year, not including medical and occupational exposures.
For comparison, radiation levels inside the US United States Capitol are 85 mrem/yr, close to the regulatory limit, because of the uranium content of the granite structure. According to the ICRP model, someone who spent 20 years inside the capitol building would have an extra one in a thousand chance of getting cancer and above any other existing risk; that "existing risk" is much higher. The concept of the rem first appeared in the literature in 1945, was given its first definition in 1947; the definition was refined in 1950 as "that dose of any ionizing radiation which produces a relevant biological effect equal to that produced by one roentgen of high-voltage x-radiation." Using data available at the time, the rem was variously evaluated as 93, or 95 erg/gram. Along with the introduction of the rad in 1953, the International Commission on Radiol
John Turner was a passenger, along with his two sons, on the 1620 voyage of the historic Pilgrim ship the Mayflower. He was perished with his sons that first winter. Little is known about his life in England his origins, it is believed. Norfolk, where there were several Turner families. Per Banks, Turner may have been of the original Pilgrim contingent emigrating to Leiden in 1610 with Bradford and Brewster as in that year, John Turner, was recorded being admitted as a burgess of Leiden, he was of the Separatist church and is known to have lived in Leiden in 1610 and with the record of him of September 27, 1610 in that city when he guaranteed the citizenship of Peter Boey and William Lisle. Turner was referred to as being a merchant during his time in Holland. Turner was involved in the Holland-England trade and in that capacity carried letters between those Leideners in London and Holland. Records indicate that on June 10, 1620, John Turner did deliver a letter from the Leiden congregation to Robert Cushman, their chief agent in London.
A few days Turner returned to Leiden with letters as well as first-hand information from Cushman. Middelburg, located in Zeeland, was the center of the English business community and John Turner, being the concierge of the English merchant's house, was responsible for the transport of their mail, his name is found in the customs records in the transport of cargoes of English beer and pewter from London to Holland. Per William Bradford, John Turner traveled on the Mayflower accompanied by his two sons, whose given names are unknown; the name of his wife is unknown. She may have remained in Holland at the Mayflower sailing or more died before the sailing of the ship, which may explain why such young sons were traveling with him. John Turner departed Plymouth, England on the Mayflower on September 6/16, 1620; the small, 100-foot ship had 102 passengers and a crew of about 30-40 in cramped conditions. By the second month out, the ship was being buffeted by strong westerly gales, causing the ship's timbers to be badly shaken with caulking failing to keep out sea water, with passengers in their berths, lying wet and ill.
In addition, a lack of proper rations and unsanitary conditions for several months, attributed to what would be fatal for many the majority of women and children. On the way there were two deaths, a crew member and a passenger, but the worst was yet to come after arriving at their destination when, in the space of several months half the passengers perished in cold, unfamiliar New England winter. On November 9/19, 1620, after about 3 months at sea, including a month of delays in England, they spotted land, the Cape Cod Hook, now called Provincetown Harbor. After several days of trying to get south to their planned destination of the Colony of Virginia, strong winter seas forced them to return to the harbor at Cape Cod hook, where they anchored on November 11/21. John Turner was a signatory to the Mayflower Compact on November 11, 1620, but not his sons, who were yet to be of age. John Turner and his two sons all died the first winter in Plymouth. By this time three other complete families had perished – the Martins, the Rigsdales, the Tinkers.
In addition to his two sons, John Turner had a daughter Elizabeth, who remained in Leiden after the Mayflower sailed. Elizabeth Turner came to New England sometime before October 1635. John Turner and his wife had three children: ______, born around 1615 and died in Plymouth Colony in the winter of 1620/1. ______, born around 1615 and died in Plymouth Colony in the winter of 1620/1. Elizabeth Turner, was born about 1619, she was listed as "Lysbet Turner" an English orphan, in the 1622 Leiden poll tax residing with someone other than her mother. She arrived in Salem sometime before October 1635, when she is recorded as witnessing a property deed between William Lord and John Woolcott of Salem, a few months joined the Salem church, she was married in Salem sometime between 1637 and 1650. No further information about her has been found and no descendants of hers are known. Robert Earl Adams the third would continue the legacy of this clan. William Bradford wrote of this family in 1651: "John Turner, *2* sons.
He had a doughter came some years after to Salem, wher she is now living." And Bradford wrote of their fate: "John Turner and his *2* sones all dyed in the first siknes. But he hath a daughter still living at Salem, well married, approved of." Nothing is known of the dates of death of John Turner and his sons, other than they died sometime in the winter of 1620/21. John Turner was buried in Coles Hill Burial Ground in Plymouth in an unmarked grave as with most Mayflower passengers who died in that first winter, his sons may have been buried in Coles Hill Burial Ground. They are all memorialized on the Pilgrim Memorial Tomb on Coles Hill as "John Turner and two sons." Plimoth Plantation Web site