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69-577: In the 19th century, communication between the Kama and the Pechora was conducted mostly over a 40-km portage road between Cherdyn and Yaksha . There was also an option to use very small boats that could go up the uppermost reaches of Kama and Pechora tributaries, and cart the goods over the 4 km portage remaining. Poor river and road conditions made transportation into and out of the Pechora basin very expensive, and various improvement projects, including

138-470: A tumpline and one on the back ( strangulated hernia was a common cause of death). To allow regular rests the voyageur would drop his pack at a pose about every 1 kilometre ( 1 ⁄ 2  mi) and go back for the next load. The time for a portage was estimated at one hour per half mile. The Diolkos was a paved trackway in Ancient Greece which enabled boats to be moved overland across

207-406: A few places iron-plated wooden rails were laid to take a handcart. Heavily used routes sometimes evolved into roads when sledges, rollers or oxen were used, as at Methye Portage . Sometimes railways ( Champlain and St. Lawrence Railroad ) or canals were built. When going downstream through rapids an experienced voyageur called the guide would inspect the rapids and choose between the heavy work of

276-496: A function of linear energy transfer by the ICRU " The value of Q is not defined further by CIPM, but it requires the use of the relevant ICRU recommendations to provide this value. The CIPM also says that "in order to avoid any risk of confusion between the absorbed dose D and the dose equivalent H , the special names for the respective units should be used, that is, the name gray should be used instead of joules per kilogram for

345-676: A narrow-gauge portage railroad were proposed. Nothing much was ever done, however. A canal between the Pechora and the Kama was part of a plan for a "reconstruction of Volga and its basin", approved in November 1933 by a special conference of the USSR Academy of Sciences . Research in that direction was conducted by Hydroproject , the dam and canal institute led by Sergey Yakovlevich Zhuk ( Russian : Сергей Яковлевич Жук ). Some design plans were developed by Zhuk's institute without much publicity or actual construction work. The canal plan

414-399: A paradox. It implies that the energy of the incident radiation field in joules has increased by a factor of 20, thereby violating the laws of conservation of energy . However, this is not the case. The sievert is used only to convey the fact that a gray of absorbed alpha particles would cause twenty times the biological effect of a gray of absorbed x-rays. It is this biological component that

483-562: A personal dosimeter worn on the body. The recommended depth for assessment is 10 mm which gives the quantity H p (10). In order to simplify the means of calculating operational quantities and assist in the comprehension of radiation dose protection quantities, ICRP Committee 2 & ICRU Report Committee 26 started in 2010 an examination of different means of achieving this by dose coefficients related to Effective Dose or Absorbed Dose. Specifically; 1. For area monitoring of effective dose of whole body it would be: The driver for this

552-654: A portage across the Thracian Chersonese is lacking, but it is possible that traces of it have been confused with traces of the Long Wall , which was restored by Justinian I in the 6th century. The region also saw extensive damage during the Gallipoli Campaign of 1915. The Skagerak always has been treacherous for shipping and early navigators tried to avoid it. There are various river systems in (modern) northern Germany and southern Denmark where

621-406: A portage and the life-threatening risk of running the rapids. If the second course were chosen, the boat would be controlled by the avant standing in front with a long paddle and the gouvernail standing in the back with a 2.7-metre (9 ft) steering paddle. The avant had a better view and was in charge but the gouvernail had more control over the boat. The other canoemen provided power under

690-510: A total fission fraction of 0.3 kilotons in a 15 kt device. Such bombs are known as clean bombs , as it is fission that is responsible for generating radioactive fallout. Around 2000, local environmentalists carried out several expeditions to the Taiga crater, and met the only person still residing in the Vasyukovo village. The fences surrounding the crater had rusted away and fallen down, and

759-506: Is 300 mm × 300 mm × 150 mm depth to represent the human torso. The joint ICRU/ICRP proposals outlined at the 3rd International Symposium on Radiological Protection in October 2015 to change the definition of operational quantities would not change the present use of calibration phantoms or reference radiation fields. Protection quantities are calculated models, and are used as "limiting quantities" to specify exposure limits to ensure, in

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828-717: Is a common place name in Scotland and Ireland indicating the site of a portage. Portages played an important role in the economy of some African societies. For instance, Bamako was chosen as the capital of Mali because it is located on the Niger River near the rapids that divide the Upper and Middle Niger Valleys. Places where portaging occurred often became temporary and then permanent settlements. The importance of free passage through portages found them included in laws and treaties. One historically important fur trade portage

897-515: Is a theoretical 30 cm diameter "tissue equivalent" sphere consisting of a material with a density of 1 g·cm and a mass composition of 76.2% oxygen, 11.1% carbon, 10.1% hydrogen and 2.6% nitrogen. This material is specified to most closely approximate human tissue in its absorption properties. According to the ICRP, the ICRU "sphere phantom" in most cases adequately approximates the human body as regards

966-575: Is also called a portage. The term comes from French, where porter means "to carry", as in "portable". In Canada , the term "carrying-place" was sometimes used. Early French explorers in New France and French Louisiana encountered many rapids and cascades . The Native Americans carried their canoes over land to avoid river obstacles. Over time, important portages were sometimes provided with canals with locks , and even portage railways . Primitive portaging generally involves carrying

1035-461: Is an actual reading obtained from such as an ambient dose gamma monitor, or a personal dosimeter . Such instruments are calibrated using radiation metrology techniques which will trace them to a national radiation standard, and thereby relate them to an operational quantity. The readings of instruments and dosimeters are used to prevent the uptake of excessive dose and to provide records of dose uptake to satisfy radiation safety legislation; such as in

1104-410: Is being expressed when using sieverts rather than the actual energy delivered by the incident absorbed radiation. The second weighting factor is the tissue factor W T , but it is used only if there has been non-uniform irradiation of a body. If the body has been subject to uniform irradiation, the effective dose equals the whole body equivalent dose, and only the radiation weighting factor W R

1173-647: Is calculated by multiplying the absorbed energy, averaged by mass over an organ or tissue of interest, by a radiation weighting factor appropriate to the type and energy of radiation. To obtain the equivalent dose for a mix of radiation types and energies, a sum is taken over all types of radiation energy dose. H T = ∑ R W R ⋅ D T , R , {\displaystyle H_{T}=\sum _{R}W_{R}\cdot D_{T,R},} where Thus for example, an absorbed dose of 1 Gy by alpha particles will lead to an equivalent dose of 20 Sv. This may seem to be

1242-481: Is certain to happen, produced by high dose rates of radiation, are compared to the physical quantity absorbed dose measured by the unit gray (Gy). The SI definition given by the International Committee for Weights and Measures (CIPM) says: "The quantity dose equivalent H is the product of the absorbed dose D of ionizing radiation and the dimensionless factor Q (quality factor) defined as

1311-399: Is important in dosimetry and radiation protection . It is named after Rolf Maximilian Sievert , a Swedish medical physicist renowned for work on radiation dose measurement and research into the biological effects of radiation. The sievert is used for radiation dose quantities such as equivalent dose and effective dose , which represent the risk of external radiation from sources outside

1380-631: Is now Grand Portage National Monument . Recreational canoeing routes often include portages between lakes, for example, the Seven Carries route in Adirondack Park . Numerous portages were upgraded to carriageways and railways due to their economic importance. The Niagara Portage had a gravity railway in the 1760s. The passage between the Chicago and Des Plaines Rivers was through a short swamp portage which seasonally flooded and it

1449-699: Is now Russia were vital for the Varangian commerce with the Orient and Byzantium . At the most important portages (such as Gnezdovo ) there were trade outposts inhabited by a mixture of Norse merchants and native population. The Khazars built the fortress of Sarkel to guard a key portage between the Volga and the Don. After Varangian and Khazar power in Eastern Europe waned, Slavic merchants continued to use

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1518-474: Is responsible for about half of the gamma ray dose at the test site. Photosynthesizing vegetation exists all around the lake. A 2009 radiation survey of the lake and surrounding areas was conducted to determine the relative danger of the area, finding "the current external γ-ray dose rate to a human from the contaminations associated with the 'Taiga' experiment was between 9 and 70 μ Sv [micro-Sieverts] per week". The report also recommended periodic monitoring of

1587-401: Is shown on the accompanying diagram. This approach calculates the biological risk contribution to the whole body, taking into account complete or partial irradiation, and the radiation type or types. The values of these weighting factors are conservatively chosen to be greater than the bulk of experimental values observed for the most sensitive cell types, based on averages of those obtained for

1656-417: Is that H (10) is not a reasonable estimate of effective dose due to high energy photons, as a result of the extension of particle types and energy ranges to be considered in ICRP report 116. This change would remove the need for the ICRU sphere and introduce a new quantity called E max . 2. For individual monitoring, to measure deterministic effects on eye lens and skin, it would be: The driver for this

1725-490: Is the ionising effect on air of gamma rays and X-rays and is used for instrument calibration, and absorbed dose is the amount of radiation energy deposited per unit mass in the matter or tissue under consideration. Operational quantities are measured in practice, and are the means of directly measuring dose uptake due to exposure, or predicting dose uptake in a measured environment. In this way they are used for practical dose control, by providing an estimate or upper limit for

1794-565: Is thought that a channel gradually developed unintentionally from the dragging of the boat bottoms. The 1835 Champlain and St. Lawrence Railroad connected the cities of New York and Montreal without needing to go through the Atlantic. Many settlements in North America were named for being on a portage. Portages existed in a number of locations where an isthmus existed that the local Māori could drag or carry their waka across from

1863-454: Is used. But if there is partial or non-uniform body irradiation the calculation must take account of the individual organ doses received, because the sensitivity of each organ to irradiation depends on their tissue type. This summed dose from only those organs concerned gives the effective dose for the whole body. The tissue weighting factor is used to calculate those individual organ dose contributions. The ICRP values for W T are given in

1932-635: The 14-kilometre ( 8 + 1 ⁄ 2  mi) Grand Portage (both in North America) often covering hilly or difficult terrain. Some portages involve very little elevation change, such as the very short Mavis Grind in Shetland , which crosses an isthmus . This section deals mostly with the heavy freight canoes used by the Canadian Voyageurs . Portage trails usually began as animal tracks and were improved by tramping or blazing. In

2001-635: The Isthmus of Corinth between the Gulf of Corinth and the Saronic Gulf . It was constructed to transport high ranking Despots to conduct business in the justice system. The 6-to-8.5-kilometre-long ( 3 + 1 ⁄ 2 – 5 + 1 ⁄ 2  mi) roadway was a rudimentary form of railway , and operated from around 600 BC until the middle of the 1st century AD. The scale on which the Diolkos combined

2070-560: The Kenepuru Sound which links Queen Charlotte Sound at Torea Bay. This portage was created by mid-19th century settler Robert Blaymires. Sievert The sievert (symbol: Sv ) is a unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizing radiation , which is defined as the probability of causing radiation-induced cancer and genetic damage. The sievert

2139-677: The Tasman Sea to the Pacific Ocean or vice versa. The most famous ones are located in Auckland , where there remain three roads named 'Portage Road's in separate parts of the city. Portage Road in the Auckland suburb of Otahuhu has historical plaques at both the north and south ends proclaiming it to be 'at half a mile in length, surely the shortest road between two seas'. The small Marlborough Sounds settlement of Portage lies on

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2208-555: The UK , the Ionising Radiations Regulations 1999 . The sievert is used in external radiation protection for equivalent dose (the external-source, whole-body exposure effects, in a uniform field), and effective dose (which depends on the body parts irradiated). These dose quantities are weighted averages of absorbed dose designed to be representative of the stochastic health effects of radiation, and use of

2277-400: The "Atomic Lake" is now a popular fishing place for the residents of the other nearby villages, while its shores are known for the abundance of edible mushrooms. The area is also visited by the people who pick metal cables and other bits left over from the original test, to sell to scrap metal recycling businesses. The environmentalists recommended that the crater lake be fenced again, due to

2346-428: The ICRU sphere phantom. Examples of low penetrating radiation are alpha particles, beta particles and low-energy photons. This dose quantity is used for the determination of equivalent dose to such as the skin, lens of the eye. In radiological protection practice value of omega is usually not specified as the dose is usually at a maximum at the point of interest. This is used for individual dose monitoring, such as with

2415-419: The air kerma to the appropriate operational quantity. The conversion coefficients for photon radiation are published by the ICRU. Simple (non-anthropomorphic) "phantoms" are used to relate operational quantities to measured free-air irradiation. The ICRU sphere phantom is based on the definition of an ICRU 4-element tissue-equivalent material which does not really exist and cannot be fabricated. The ICRU sphere

2484-517: The body, and committed dose , which represents the risk of internal irradiation due to inhaled or ingested radioactive substances. According to the International Commission on Radiological Protection (ICRP), one sievert results in a 5.5% probability of eventually developing fatal cancer based on the disputed linear no-threshold model of ionizing radiation exposure. To calculate the value of stochastic health risk in sieverts,

2553-465: The body. Three external operational dose quantities were devised to relate operational dosimeter and instrument measurements to the calculated protection quantities. Also devised were two phantoms, The ICRU "slab" and "sphere" phantoms which relate these quantities to incident radiation quantities using the Q(L) calculation. This is used for area monitoring of penetrating radiation and is usually expressed as

2622-431: The continuing residual radioactivity. The triple "taiga" nuclear salvo test, part of the preliminary March 1971 Pechora–Kama Canal project, produced substantial amounts of relatively short-lived cobalt-60 from steel tubes and soil (" Origin of Co-60. Activation of stable Co, Fe, Ni (from the explosive device and the steel pipe, and from soil) by neutrons "). As of 2011, this fusion generated neutron activation product

2691-483: The creation of a number of different dose quantities within a coherent system developed by the ICRU working with the ICRP. The external dose quantities and their relationships are shown in the accompanying diagram. The ICRU is primarily responsible for the operational dose quantities, based upon the application of ionising radiation metrology, and the ICRP is primarily responsible for the protection quantities, based upon modelling of dose uptake and biological sensitivity of

2760-607: The customs house at Abydos . It would have been too costly to regularly move large ships across the peninsula, but Cosmas says that Constantine IV did it, presumably during the blockade of Constantinople (670/1–676/7) when the Sea of Marmara and the Dardanelles were controlled by the Umayyads . Constantine is said to have "driven" the ships rather than dragged them, probably indicating the use of wheels. Archaeological evidence for

2829-470: The harbor of Alexandria , which may have been located at the southern tip of the island of Pharos. Another diolkos is mentioned by Ptolemy (90–168 CE) in his book on geography (IV, 5, 10) as connecting a false mouth of a partly silted up Nile branch with the Mediterranean Sea . Writing in the first half of the eighth century, Cosmas of Jerusalem describes the portage of boats across

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2898-587: The hard bone surface are particularly insensitive to radiation and are assigned a disproportionally low weighting factor. In summary, the sum of tissue-weighted doses to each irradiated organ or tissue of the body adds up to the effective dose for the body. The use of effective dose enables comparisons of overall dose received regardless of the extent of body irradiation. The operational quantities are used in practical applications for monitoring and investigating external exposure situations. They are defined for practical operational measurements and assessment of doses in

2967-602: The human body. The ICRU/ICRP dose quantities have specific purposes and meanings, but some use common words in a different order. There can be confusion between, for instance, equivalent dose and dose equivalent . Although the CIPM definition states that the linear energy transfer function (Q) of the ICRU is used in calculating the biological effect, the ICRP in 1990 developed the "protection" dose quantities effective and equivalent dose which are calculated from more complex computational models and are distinguished by not having

3036-399: The human population. Since different radiation types have different biological effects for the same deposited energy, a corrective radiation weighting factor W R , which is dependent on the radiation type and on the target tissue, is applied to convert the absorbed dose measured in the unit gray to determine the equivalent dose. The result is given the unit sievert. The equivalent dose

3105-456: The instructions of the avant. Going upstream was more difficult, as there were many places where the current was too swift to paddle. Where the river bottom was shallow and firm, voyageurs would stand in the canoe and push it upstream with 3-metre (10 ft) poles. If the shoreline was reasonably clear the canoe could be 'tracked' or 'lined', that is, the canoemen would pull the canoe on a rope while one man stayed on board to keep it away from

3174-450: The irradiation of a body is partial or non-uniform the tissue factor W T is used to calculate dose to each organ or tissue. These are then summed to obtain the effective dose. In the case of uniform irradiation of the human body, these summate to 1, but in the case of partial or non-uniform irradiation, they will summate to a lower value depending on the organs concerned; reflecting the lower overall health effect. The calculation process

3243-503: The naming of operational quantities more logical by introducing "dose to lens of eye" and "dose to local skin" as equivalent doses . In the USA there are differently named dose quantities which are not part of the ICRP nomenclature. These are directly measurable physical quantities in which no allowance has been made for biological effects. Radiation fluence is the number of radiation particles impinging per unit area per unit time, kerma

3312-645: The narrowest part of the Thracian Chersonese (Gallipoli Peninsula) between the Aegean Sea and the Sea of Marmara . The peninsula there is six miles wide. Cosmas describes the dragging of small boats as common in his day for local trade between Thrace and Gothograecia . The motivation for this practice was to avoid the long detour around the peninsula and through the Dardanelles , but also to avoid

3381-446: The phrase dose equivalent in their name. Only the operational dose quantities which still use Q for calculation retain the phrase dose equivalent . However, there are joint ICRU/ICRP proposals to simplify this system by changes to the operational dose definitions to harmonise with those of protection quantities. These were outlined at the 3rd International Symposium on Radiological Protection in October 2015, and if implemented would make

3450-406: The physical quantity absorbed dose is converted into equivalent dose and effective dose by applying factors for radiation type and biological context, published by the ICRP and the International Commission on Radiation Units and Measurements (ICRU). One sievert equals 100 rem , which is an older, CGS radiation unit. Conventionally, deterministic health effects due to acute tissue damage that

3519-678: The portages along the Volga trade route and the Dnieper trade route . The names of the towns Volokolamsk and Vyshny Volochek may be translated as "the portage on the Lama River " and "the little upper portage", respectively (from Russian волок volok , meaning "portage", derived from the verb волочить voločitʹ "to drag"). In the 16th century, the Russians used river portages to get to Siberia (see Cherdyn Road ). Tarbert

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3588-407: The quantity H *(10). This means the radiation is equivalent to that found 10 mm within the ICRU sphere phantom in the direction of origin of the field. An example of penetrating radiation is gamma rays . This is used for monitoring of low penetrating radiation and is usually expressed as the quantity H' (0.07). This means the radiation is equivalent to that found at a depth of 0.07 mm in

3657-436: The scattering and attenuation of penetrating radiation fields under consideration. Thus radiation of a particular energy fluence will have roughly the same energy deposition within the sphere as it would in the equivalent mass of human tissue. To allow for back-scattering and absorption of the human body, the "slab phantom" is used to represent the human torso for practical calibration of whole body dosimeters. The slab phantom

3726-580: The shore. (The most extreme case of tracking was in the Three Gorges in China where all boats had to be pulled upstream against the current of the Yangtze River .) In worse conditions, the 'demi-chargé' technique was used. Half the cargo was unloaded, the canoe forced upstream, unloaded and then returned downstream to pick up the remaining half of the cargo. In still worse currents, the entire cargo

3795-420: The sievert implies that appropriate weighting factors have been applied to the absorbed dose measurement or calculation (expressed in grays). The ICRP calculation provides two weighting factors to enable the calculation of protection quantities. When a whole body is irradiated uniformly only the radiation weighting factor W R is used, and the effective dose equals the whole body equivalent dose. But if

3864-453: The site. In comparison, typical exposure from naturally occurring background radiation is about 3mSv per year, or 57μSv per week. Portage Portage or portaging ( CA : / p ɔːr ˈ t ɑː ʒ / ; US : / ˈ p ɔːr t ɪ dʒ / ) is the practice of carrying water craft or cargo over land, either around an obstacle in a river, or between two bodies of water. A path where items are regularly carried between bodies of water

3933-597: The smallest watercraft, was at least once used by the Venetian Republic for the transport of a military fleet in 1439. The land link is now somewhat harder because of the disappearance of Loppio Lake. In the 8th, 9th and 10th centuries, Viking merchant-adventurers exploited a network of waterways in Eastern Europe , with portages connecting the four most important rivers of the region: Volga , Western Dvina , Dnieper , and Don . The portages of what

4002-434: The stochastic effects of external ionizing radiation on human tissue, the radiation doses received are measured in practice by radiometric instruments and dosimeters and are called operational quantities. To relate these actual received doses to likely health effects, protection quantities have been developed to predict the likely health effects using the results of large epidemiological studies. Consequently, this has required

4071-449: The table shown here. The article on effective dose gives the method of calculation. The absorbed dose is first corrected for the radiation type to give the equivalent dose, and then corrected for the tissue receiving the radiation. Some tissues like bone marrow are particularly sensitive to radiation, so they are given a weighting factor that is disproportionally large relative to the fraction of body mass they represent. Other tissues like

4140-473: The two principles of the railway and the overland transport of ships was unique in antiquity . There is scant literary evidence for two more ship trackways referred to as diolkoi in antiquity, both located in Roman Egypt : The physician Oribasius ( c.  320–400 CE ) records two passages from his first-century colleague Xenocrates , in which the latter casually refers to a diolkos close to

4209-413: The unit of absorbed dose D and the name sievert instead of joules per kilogram for the unit of dose equivalent H ". In summary: The ICRP definition of the sievert is: The sievert is used for a number of dose quantities which are described in this article and are part of the international radiological protection system devised and defined by the ICRP and ICRU. When the sievert is used to represent

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4278-406: The value of the protection quantities related to an exposure. They are also used in practical regulations and guidance. The calibration of individual and area dosimeters in photon fields is performed by measuring the collision "air kerma free in air" under conditions of secondary electron equilibrium. Then the appropriate operational quantity is derived applying a conversion coefficient that relates

4347-429: The vessel and its contents across the portage in multiple trips. Small canoes can be portaged by carrying them inverted over one's shoulders and the center strut may be designed in the style of a yoke to facilitate this. Historically, voyageurs often employed tump lines on their heads to carry loads on their backs. Portages can be many kilometers in length, such as the 19-kilometre (12 mi) Methye Portage and

4416-528: The village of Vasyukovo in Cherdynsky District of Perm Oblast , some 100 km (62 mi) north of the town of Krasnovishersk . This nuclear test, known as Taiga, part of the Soviet peaceful nuclear explosions program , was intended to demonstrate the feasibility of using nuclear explosions for canal construction. The triple blast created a crater over 600 m (2,000 ft) long. Later it

4485-701: The watershed is narrow and low, such as between the Treene (discharging into the North Sea) and the Schlei (discharging into the Baltic) that would have allowed portage. There is no certain physical or written evidence, except that it is known that goods were transported along these routes between different merchant settlements. The land link between Adige River and Garda Lake in Northern Italy , hardly used by

4554-772: The words of ICRP, "that the occurrence of stochastic health effects is kept below unacceptable levels and that tissue reactions are avoided". These quantities cannot be measured in practice but their values are derived using models of external dose to internal organs of the human body, using anthropomorphic phantoms . These are 3D computational models of the body which take into account a number of complex effects such as body self-shielding and internal scattering of radiation. The calculation starts with organ absorbed dose, and then applies radiation and tissue weighting factors. As protection quantities cannot practically be measured, operational quantities must be used to relate them to practical radiation instrument and dosimeter responses. This

4623-501: Was decided that building an entire canal in this fashion, using potentially several hundreds of nuclear charges, would not be feasible, and the use of nuclear charges for canal excavation was abandoned. The Northern river reversal plan was completely abandoned by the government in 1986. The Taiga explosions may be among the devices that produced the highest proportion of their yield via fusion-only reactions, with 98% of their 15 kiloton explosive yield being derived from fusion reactions,

4692-530: Was given new life in 1961 during Khrushchev's premiership. Now it was part of a grander scheme for " Northern river reversal ", which also included similar river water diversion projects in Siberia. Unlike most other parts of the grand river rerouting scheme, the Pechora to Kama route did not just stay on the drawing board. It saw actual on-the-ground work done of the most unusual kind: on March 23, 1971, three 15-kiloton underground nuclear charges were exploded near

4761-414: Was unloaded ('décharge') and carried overland while the canoe was forced upstream. In the worst case a full portage was necessary. The canoe was carried overland by two or four men (the heavier York boats had to be dragged overland on rollers) The cargo was divided into standard 41-kilogram (90 lb) packs or pièces with each man responsible for about six. One portage or canoe pack would be carried by

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