Image ThermohalineCirculation 2.png A summary of the path of the thermohalinecirculation Great Ocean ... 400px right The term thermohalinecirculation THC refers to the part of the large scale ocean circulation ... and gases around the globe. As such, the state of the circulation has a large impact on the climate of the Earth . The thermohalinecirculation is sometimes called the ocean conveyor belt , the great ... is the thermohalinecirculation? journal Science volume 298 issue 5596 pages 1179 1181 doi 10.1126 ... densities must flow, providing a driving force for deep currents. The thermohalinecirculation is mainly ... 1.8 C. fact date December 2010 Movement of thermohalinecirculation Formation and movement ... evaporative cooling and sinks to the ocean floor, providing a continuous thermohalinecirculation ... current that continues the Gulf Stream northeast, is largely driven by the global thermohalinecirculation ... climate The thermohalinecirculation plays an important role in supplying heat to the polar regions ... as the thermohalinecirculation governs the rate at which deep waters are exposed to the surface, it may .... While it is often stated that the thermohalinecirculation is the primary reason that Western Europe ... circulation under global warming, see shutdown of thermohalinecirculation . See also Atlantic ... Halothermal circulation Hydrothermal circulation Upwelling Shutdown of thermohalinecirculation ... year 2005 cite book author Rahmstorf, S. chapter Thermohaline Ocean Circulation chapterurl http www.pik ... author Rahmstorf, S. title The concept of the thermohalinecirculation journal Nature volume 421 pages ..., Oceanographic and Climate Models Ocean Physical oceanography DEFAULTSORT ThermohalineCirculation ... tsirkulatsioon es Circulaci n termohalina fa fr Circulationthermohaline gl Circulaci n .... The adjective thermohaline derives from thermo referring to temperature and salinity haline referring ... and meridional meridional overturning circulation often abbreviated as MOC . The term MOC, however ... more details
Image ThermohalineCirculation 2.png A summary of the path of the thermohalinecirculation. Blue paths ... or slowdown of the thermohalinecirculation is a postulated Effects of global warming effect of global warming . There is some speculation that global warming could, via a shutdown or slowdown of the thermohalinecirculation, trigger localised cooling in the North Atlantic and lead to cooling, or lesser ... November pmid 17136090 doi 10.1038 nature05277 ref Thermohalinecirculation and fresh water Heat ... clear that sufficient freshwater could be provided to interrupt thermohalinecirculation ... Global climatic impacts of a collapse of the Atlantic thermohalinecirculation . Climatic Change 54 ... gyre on the thermohalinecirculation journal Science volume 309 issue 5742 pages 1841 4 year 2005 month ... large enough to shut down the thermohalinecirculation would be an order of magnitude greater than currently ..., a thermohalinecirculation shutdown could have other major consequences apart from cooling ... ThermohalineCirculation, Michael E. Schlesinger et al. Global warming physical oceanography use ... of this circulation is the Gulf Stream, a wind driven gyre , which transports warm water from the Caribbean northwards. A northwards branch of the Gulf Stream, the North Atlantic Drift, is part of the thermohalinecirculation THC , transporting warmth further north to the North Atlantic, where its ... of sea ice further increases the salinity. This dense water then sinks and the circulation stream ... global climate model Atmosphere Ocean General Circulation Models the THC tends to weaken somewhat ..., there is still a warming over Europe . ref http www.grida.no climate ipcc tar wg1 357.htm Thermohalinecirculation changes . From IPCC Working Group 1, chapter 9. ref Model runs in which the THC is forced ... Bjerknes Centre for Climate Research ref This suggests that either the circulation is not weakening ... www.realclimate.org index.php?p 225 Decrease in Atlantic circulation? RealClimate.org, 30 Nov 2005 ... more details
wiktionarypar circulationCirculation may refer to Circulatory system , a biological organ system whose primary function is to move substances to and from cells Circulation fluid dynamics , the path integral of the fluid velocity around a closed curve Circulation journal , one of the journals published by American Heart Association Circulation architecture , the flow of people through a building Exhaust gas recirculation , a nitrogen oxide reduction technique used in most gasoline and diesel engines Atmospheric circulation , the large scale movement of air Newspaper circulation , the average number of copies of a newspaper distributed on a day Magazine circulation , the average number of copies of a periodical distributed per edition volume Circulation UK duo , a UK house music duo Circulation problem , a generalization of network flow problems Library circulation , the activities around the lending of library books and other material to users of a lending library Circulation currency , all currency held by consumers and businesses, but not by financial institutions and governments Circulation Festival, an annual circus and Fire dancing fire performance festival held in Dunedin , New Zealand See also List of circulating currencies disambig ca Circulaci es Circulaci n fr Circulation it Circolazione nl Circulatie pt Circula o ru simple Circulation ... more details
The term halothermal circulation refers to the part of the large scale ocean circulation that is driven by global Density gradient density gradients created by surface heat and evaporation. The adjective halothermal derives from salinity halo referring to salt content and thermo thermal referring to temperature, factors which together determine the Water molecule Density of saltwater and ice density of sea water . Halothermal circulation is driven primarily by salinity changes and secondarily by temperature changes as opposed to the Thermohalinecirculationthermohaline mode in modern oceans . The generation of high salinity surface waters at low latitudes, which were therefore of higher density and thus sank, is thought to have been the dominant ocean circulation driver during Greenhouse and icehouse Earth greenhouse climate s such as the Cretaceous . Similar dynamics operate today in the Mediterranean . The formation of bottom waters by halothermal dynamics is considered to be one to two orders of magnitude weaker than in thermohaline systems. References Kennett, J.P. & Stott, L.D., 1990, Proteus and Proto Oceanus, Paleogene oceans as revealed from Antarctic stable isotope results, ODP Leg 113. Proceedings Ocean Drilling Program, Science Results 113 , 865 880. physical oceanography Category Physical oceanography Category Geological processes ... more details
Sustainable development convection ocean current thermohalinecirculation metamorphic rocks volcanogenic ...Hydrothermal circulation in its most general sense is the circulation of hot water hydros in the Greek meaning water and thermos meaning heat. Hydrothermal circulation occurs most often in the vicinity of sources of heat within the Earth s Crust geology crust . This generally occurs near volcanic activity, but can occur in the deep crust related to the intrusion of granite , or as the result of orogeny or metamorphism . Seafloor hydrothermal circulation Hydrothermal circulation in the ocean s is the passage of the water through mid oceanic ridge systems. The term includes both the circulation of the well known, high temperature vent waters near the ridge crests, and the much lower temperature, diffusion diffuse flow of water through sediments and buried basalt s further from the ridge crests. The former circulation type is sometimes termed active , and the latter passive . In both cases the principle is the same cold dense seawater sinks into the basalt of the seafloor and is heated at depth whereupon it rises back to the rock ocean water interface due to its lesser density. The heat source for the active vents is the newly formed basalt, and, for the highest temperature vents, the underlying magma chamber. The heat source for the passive vents is the still cooling older basalts. Heat flow studies of the seafloor suggest that basalts within the oceanic crust take millions of years to completely cool as they continue to support passive hydrothermal circulation systems. Hydrothermal vent s are locations on the seafloor where hydrothermal fluids mix into the overlying ocean. Perhaps ... related hydrothermal circulation Hydrothermal circulation is not limited to ocean ridge environments ... with the groundwater system. Deep crust Hydrothermal also refers to the transport and circulation of water ... Hydrothermal circulation, particularly in the deep crust, is a primary cause of mineral deposit ... more details
Unreferenced date December 2009 A secondary circulation is a circulation induced in a rotating system. For example, the primary circulation of Earth s atmosphere is zonal . If however a parcel of air, that moves in a purely zonal direction, is accelerated or decelerated zonally, the Coriolis force will add a meridional component to its velocity. This meridional circulation is then the secondary circulation. See also Hough function Primitive equations Secondary flow DEFAULTSORT Secondary Circulation Category Geophysics Category Physical oceanography Category Atmospheric dynamics Category Fluid mechanics Fluiddynamics stub nn Sekund r sirkulasjon ... more details
Unreferenced stub auto yes date December 2009 Library circulation or library lending comprises the activities around the lending of library books and other material to users of a lending library . A circulation or lending department is one of the key departments of a library. The main public service point is the circulation desk or loans desk, usually found near the main entrance of a library. It provides lending services and facilities for return of loaned items. Renewal of materials and payment of fines are also handled at the circulation desk. Circulation staff may provide basic search and reference services, though more in depth questions are usually referred to reference librarians at the library reference desk . The circulation desk is in most cases staffed by library aides instead of professional librarians. Functions of the circulation desk staff may include Lending materials to library users Checking in materials returned Monitoring materials for damage and routing them to the appropriate staff for repair or replacement Troubleshooting circulation technology, i.e. library circulation software, scanners, printers, etc. Collecting statistics on library use, i.e. patron transactions, material checkouts, etc. Reserve The circulation desk can also look after the reserve section such as past exam papers and unit materials. Infringement processing The payment of infringements for late, lost book charges and overdue items are processed by the circulation desk. They can also lift restrictions for library patrons once the fines have been paid. Shelving The circulation desk also handles the shelving of items used from the Reserve section and also the reference section. Lost and found Some circulation desks also provide a lost and found service. This includes commonly found items such as library cards matric card, laptops, wallets, computer media and portable devices. See also Interlibrary loan Library reference desk DEFAULTSORT Library Circulation Category Library science ... more details
In the field of architecture , circulation refers to the way people move through and interact with a building. ref http www.britannica.com EBchecked topic 118392 circulationcirculation architecture in Britannica Online Encyclopedia ref In public buildings, circulation is of high importance for example, in buildings such as museums , it is key to have a floor plan that allows continuous movement while minimizing the necessity to retrace one s steps, allowing a visitor to see each work in a sequential, natural fashion. Structures such as elevator s, escalators , and staircases are often referred to as circulation elements, as they are positioned and designed to optimize the flow of people through a building. References references Category Architectural design Architecture stub ... more details
Enteroenteric circulation is the secretion back into the intestines of substances previously taken up from it. It occurs when there is a negative relative concentration of substance in the intestines, making it passively diffuse from the mesenteric circulation into the intestinal lumen and is trapped. ref name CNYPCC http www.upstate.edu poison pdf tox newsletter 04 01toxnews.pdf The CNYPCC Toxicology Letter Vol. VI No. 2. Central New York Regional Poison Control Center. April, 2001 ref Examples of toxins that exhibit enteroenteric circulation include theophylline , phenobarbital , and phenytoin . ref name CNYPCC Administration of activated charcoal inhibits the enteroenteric circulation of such substances, and is therefore useful in overdose or intoxication. ref http www.medscape.com viewarticle 471331 medscape.com Use of Activated Charcoal in Drug Overdose. By Desiree Lie, MD, MSEd. Posted 25 March 2004 ref See also Enterohepatic circulation References Reflist Category Gastroenterology Medicine stub ... more details
Infobox journal title Circulation cover File Circulation journal cover.gif editor Joseph Loscalzo discipline ... 7322 eISSN 1524 4539 boxwidth Circulation is a scientific journal published by Lippincott Williams ... ref 2008 saw the appearance of six subspecialty journals. The first edition of Circulation Arrhythmia ... pmid 19808386 ref followed by an edition dedicated to heart failure in May titled Circulation Heart Failure Circ Heart Fail . ref cite journal author Udelson JE title The inaugural issue of Circulation ... per month from July through October 2008. In order of release they were, Circulation Cardiovascular ... 1 pages 1 doi 10.1161 CIRCIMAGING.108.793083 ref , Circulation Cardiovascular Interventions Circ Cardiovasc Intervent ref cite journal author Faxon D title Circulation Cardiovascular Interventions ... 1 pages 1 doi 10.1161 CIRCINTERVENTIONS.108.799270 pmid 20031647 ref , Circulation Cardiovascular Quality and Outcomes Circ Cardiovasc Qual Outcomes ref cite journal author Krumholz H title Circulation ... 1 doi 10.1161 CIRCOUTCOMES.108.814509 pmid 20031779 ref , and Circulation Cardiovascular Genetics Circ ... The Inauguration of Circulation Cardiovascular Genetics journal Circ Cardiovasc Genet year 2008 ... access policy All Circulation papers are available for free full text Open access publishing open access ... http circ.ahajournals.org Circulation home page http circep.ahajournals.org Circulation Arrhythmia and Electrophysiology home page http circheartfailure.ahajournals.org Circulation Heart Failure home page http circimaging.ahajournals.org Circulation Cardiovascular Imaging home page http circinterventions.ahajournals.org Circulation Cardiovascular Interventions home page http circoutcomes.ahajournals.org Circulation Cardiovascular Quality and Outcomes home page http circgenetics.ahajournals.org Circulation ... page DEFAULTSORT Circulation Journal med journal stub Category Cardiology journals Category Publications ... journals fr Circulation journal nl Circulation ja ... more details
Unreferenced stub auto yes date December 2009 Collateral circulation is when an area of tissue or an organ has a number of different pathways for blood to reach it. This is often as a result of Circulatory anastomosis anastamoses branches formed between adjacent blood vessels. An example of the usefulness of collateral circulation is a systemic thrombo embolism in cats. This is when a thrombus lodges above the external iliac artery Common Iliac Artery , blocking the external and internal iliac arteries and effectively shutting off all blood supply to the hind leg. Even though the main vessels to the leg are blocked, enough blood can get to the tissues in the leg via the collateral circulation in order to keep them alive. DEFAULTSORT Collateral Circulation Category Cardiovascular system Circulatory stub ... more details
A newspaper s circulation is the number of copies it distributes on an average day. Newspaper circulation rates are currently experiencing a downward trend. Circulation is one of the principal factors used to set advertising rates. Circulation is not always the same as copies sold, often called paid circulation , since some newspapers are distributed without cost to the reader. Readership figures are usually higher than circulation figures because of the assumption that a typical copy of the newspaper .... World newspapers with the largest circulation The World Association of Newspapers WAN publishes a list of newspapers with the largest circulation. In 2005, China topped the list in term of total newspaper circulation with 93.5 million a day, India came second with 78.8 million, followed by Japan, with 70.4 ... are still the List of newspapers in the world by circulation largest circulated newspapers in the world ... is the List of newspapers in the world by circulation largest circulated English language daily ... is the most popular paper in China. The List of newspapers in the United States by circulation ... having eclipsed the former for a period of years but according to its own press kit, the circulation ... Book of Records , the daily circulation of the Soviet newspaper Komsomolskaya Pravda Russian ... i Fakty boasted a circulation of 33,500,000 in 1991. Individual countries Belgium The Belgian institution CIM Centre for Information about Media publishes national circulation figures for all written ... , 73,784. Canada see List of Canadian newspapers by circulation The most widely read paper in the country ... papers don t. India see List of newspapers in India by circulation The 2010 Indian Readership Survey ... in Malayalam from Kerala, currently has a readership of over 9.9 million with a circulation base of over 1.8 million copies has the most circulation in regional languages. Japan main List of newspapers in Japan The 2004 circulation figures for the morning and evening editions of Japan s largest ... more details
File Langmuir Circulation.jpg right thumb Langmuir circulation File Rodeo Lagoon From Trail.JPG thumb right White streaks in this lagoon are due to the Langmuir circulation. File Lines of sargassum Sargasso Sea.jpg thumb right These lines of sargassum can stretch for miles along the surface. The clumps of floating algae are often concentrated by the strong winds and wave action associated with the Gulf Stream . Langmuir circulation is a wind driven helix circulation in the ocean with the axis almost parallel to the wind. Irving Langmuir discovered this phenomenon after noticing windrow s of seaweed in the Sargasso Sea in 1938. ref The open university, Ocean circulation Butterworth Heinemann second edition 2001 ref The circulation was found to be 15 to the right of the wind in the northern hemisphere ref Stewart, Robert H., Introduction To Physical Oceanography , Copyright 2002 Fall 2002 Edition ref and the helix forming bands of divergence and Convergence zone convergence at the surface. At the convergence zones floating seaweed, foam and debris will concentrate and form the bands Langmuir noticed in 1938. At the surface the circulation will set a current from the divergence zone to the convergence zone and the spacing between these zones are of the order 15 300 m. Below convergence zones narrow jets of downward flow form and the magnitude of the current will be comparable to the horizontal flow. The downward propagation will typically be in the order of meters or tenths of meters and will not penetrate the pycnocline . The upwelling will generally be less intense and take place over a wider band under the divergence zone. In an observation done at windspeeds of 14 m s sup 1 sup the horizontal spacing of the cells were 20 m and maximum vertical velocity was 18 cm s sup 1 sup . Citation needed date June 2010 References Reflist External links Commons category Langmuir circulation physical oceanography Category Oceanography Category Physical ... more details
With regards to a particular currency , circulation refers to the total wealth of that currency whether banknotes , coins , or demand deposits that is engaged in that currency s economy at a given time. ref http financial dictionary.thefreedictionary.com Currency in circulation Currency in circulation at the Free Online Dictionary ref Circulation can also refer to the metaphorical or literal movement of wealth due to transactions between the holders of a currency. The euro , the official currency of the European Union , is currently the currency with the highest combined value of cash circulation in the world. ref cite web last Atkins first Ralph title Euro notes cash in to overtake dollar publisher Financial Times date 2006 12 27 url http www.ft.com cms s 18338034 95ec 11db 9976 0000779e2340.html accessdate 2007 05 04 ref Total currency in circulation In 1990 , total Money supply currency in circulation passed 1 Orders of magnitude numbers 1012 trillion USD . After 12 years, in 2002 this total money supply in the world was 2 trillion USD. And just after 6 years, in 2008 , this money supply increased to 4 trillion USD. European Union 1035.2 1000000000 number billion USD , 24.30 USA 850.7 billion USD, 19.97 Japan 762.4 billion USD, 17.90 China 492.3 billion USD, 11.56 India 140.3 billion USD, 3.29 Russia 110.8 billion USD, 2.60 UK 87.5 billion USD, 2.05 Canada 43.8 billion USD, 1.03 Switzerland 40.3 billion USD, 0.95 Poland 37.7 billion USD, 0.89 Brazil 37.3 billion USD, 0.88 Mexico 34.3 billion USD, 0.81 Australia 32.4 billion USD, 0.76 Other countries 554.9 billion USD, 13.03 ref http www.marketoracle.co.uk Article11576.html ref See also List of circulating currencies References references DEFAULTSORT Circulation Currency Category Currency Economics stub ... more details
Image Enterohepatic.JPG thumb right Enterohepatic Circulation. confused2 the hepatic portal system which directs nutrient rich blood from the intestines to the liver Enterohepatic circulation refers to the circulation of biliary acid s from the liver , where they are produced and secreted in the bile , to the small intestine , where it aids in digestion of fats and other substances, back to the liver. ref name urlSect. 6, Ch. 5 Enterohepatic Circulation of Bile Acids cite web url http www.lib.mcg.edu edu eshuphysio program section6 6ch5 s6ch5 17.htm title Sect. 6, Ch. 5 Enterohepatic Circulation of Bile Acids format work accessdate ref Endogenous bacteria play an important role in enterohepatic circulation. ref name urlMetabolic Activities of the Microflora cite web url http www.ncbi.nlm.nih.gov books bv.fcgi?indexed google&rid mmed.section.5106 title Metabolic Activities of the Microflora format work accessdate ref Hepatocytes metabolize cholesterol to cholic acid and chenodeoxycholic acid . These lipid soluble bile acid s are conjugated mainly to glycine or taurine molecules to form water soluble primary conjugated bile acids, sometimes called bile salts . These bile acids travel to the gall bladder during the interdigestive phase for storage and to the descending part of the duodenum ... acids which are delivered to the duodenum will be recycled by the enterohepatic circulation. Due to the pH ... bile salts are reabsorbed actively into hepatic portal circulation. Bacteria deconjugate some of the primary ... absorbed into hepatic portal circulation. Finally, the conjugated bile acids which remained un ionized ..., and little escapes the healthy liver into systemic circulation. If bile does escape, jaundice ... about 20 times, often multiple times during a single digestive phase. Drugs Enterohepatic circulation ... remain in the enterohepatic circulation for a prolonged period of time as a result of this recycling process. See also Enteroenteric circulation References reflist External links GPnotebook 1040580666 ... more details
Natural circulation refers to the ability of a fluid in a system to circulate continuously, with gravity and changes in heat energy temperature being the only driving force. This force is known as thermal head or thermal driving head. A fluid system designed for natural circulation will have a heat source and a heat sink . Each of these is in contact with some of the fluid in the system, but not all of it. The heat source is positioned lower than the heat sink. Most materials that are fluid at common temperatures expand when they are heated, becoming less density dense . Correspondingly, they become denser when they are cooled. At the heat source of a system of natural circulation, the heated fluid becomes lighter than the fluid surrounding it, and thus rises. At the heat sink, the nearby fluid becomes denser as it cools, and is drawn downward by gravity. Together, these effects create a flow of fluid from the heat source to the heat sink and back again. Systems of natural circulation include tornado es and other weather weather systems , ocean current s, and household Ventilation architecture ventilation . Some solar water heaters use natural circulation. In a nuclear reactor , natural circulation can be a design criterion. It is achieved by reducing turbulence and friction in the fluid flow that is, minimizing head loss , and by providing a way to remove any inoperative pumps ... or turbines the heat sink . In this way, natural circulation will ensure that the fluid will continue ... at a significant fraction of full power under natural circulation, quieting those propulsion plants. The S6G reactor cannot operate at power under natural circulation, but can use it to maintain emergency cooling while shut down. By the nature of natural circulation, fluids do not typically move very ... reactors, even ones designed to primarily use natural circulation as the main method of fluid circulation, have pumps that can circulate the fluid in the case that natural circulation is not sufficient ... more details
Image Illu systemic circuit.svg thumb 300px Systemic circulation is the part of the cardiovascular system which carries oxygen ated blood away from the heart to the body , and returns deoxygenated blood back to the heart. This physiologic theory of circulation was first described by William Harvey . This term is opposed and contrasted to the term pulmonary circulation first proposed by Ibn al Nafis . ref cite book last Maton first Anthea authorlink coauthors Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright title Human Biology and Health publisher Prentice Hall date 1993 location Englewood Cliffs, New Jersey pages url doi id isbn 0 13 981176 1 ref Course Systemic circulation refers to the part of the circulatory system in which the blood leaves the heart, services the body s cells, and then re enters the heart. Blood leaves through the left ventricle to the aorta, the body s largest artery. The aorta leads to smaller arteries, arterioles, and finally capillaries. Waste and carbon dioxide diffuse out of the cell into the blood and oxygen in the blood diffuses out of the blood and into the cell, blood then moves to venious capularies ... blood enters the systemic circulation when leaving the left ventricle , through the aortic semilunar valve . The first part of the systemic circulation is the aorta , a massive and thick walled ... . Coronary vessels Mainarticle Coronary circulation The heart itself is supplied with oxygen and nutrients through a small loop of the systemic circulation. Portal veins The general rule is that arteries ... vein branches into a second capillary system in the liver . Advantage Because the systemic circulation is powered by the left ventricle which is very muscular , one advantage of this form of circulation as opposed to open circulation , or the gill system that fish use to breathe is that there is simultaneous ... Dr. Matayoshi References references Smart Science Textbooks ,Philippines See also Pulmonary circulation ... more details
Orphan date February 2009 Brain circulation is a concept that is posited By whom date December 2009 as a counter factual to the idea of brain drain . The concept of brain drain gained popularity as skilled labour from certain countries emigrated to other countries in search of better opportunities. In India for example, one witnessed large scale emigration of engineers from its premier engineering institutes called IIT Indian Institute of Technology in the sixties, seventies and eighties. Some commentators Who date March 2009 felt that this led to a loss of intellectual capital from the country and coined the term brain drain to signify this process. The late nineties and the early years of the 21st century however saw large numbers of these emigrants returning back to India as prospects in India improved markedly, brought on by important economic reforms initiated in the early nineties. Some ... knowledge that proves invaluable for the country s development. Brain circulation can thus be defined as the circular movement of skilled labour across nations. Brain circulation vs brain drain When ... to tap into them, and such a process is called Brain Circulation. The story has been mixed so far. In some cases like Taiwan , Greater China and India, countries have profited enormously from brain circulation, while in others, brain circulation does not seem to happen in a significant way. Why brain circulation can be witnessed in certain contexts and not in others is a question that is at the forefront ... Mobility of Scientists and Engineers to the United States Brain Drain or Brain Circulation ..., Yevgeny, 2005, From Brain Drain to Brain Circulation Emerging Policy Agenda, Presentation to the Office ..., AnnaLee, 2002, Brain Circulation How High Skilled Immigration Makes Everyone Better off, The Brookings Review, Vol 20, No.1 Saxenian, AnnaLee, 2005, From Brain Drain to Brain Circulation Transnational ... Circulation Category Human migration ... more details
unreferenced date September 2008 Lost circulation can be one of the more serious problems that can arise during the drilling of an oil well or gas well . Circulation is said to be lost when the drilling fluid , known commonly as mud , flows into one or more geological formations instead of returning up the annulus oil well annulus . Consequences The consequences of lost circulation can be as little as the loss of a few dollars of drilling fluid , or as disastrous as a blowout well drilling blowout and loss of life, so close monitoring of tanks, pits, and flow from the well, to quickly assess and control lost circulation, is taught and practiced. If the fluid in the wellbore drops due to lost circulation or any other reason , hydrostatic pressure is reduced, thus allowing a gas or fluid, which is under a higher pressure than the reduced hydrostatic pressure , to influx into the wellbore . Another consequence of lost circulation is called dry drilling . Dry drilling occurs when fluid is completely lost from the well bore without actual drilling coming to a stop. The effects of dry drilling can be as minor as destroying a bit to as serious as major damage to the wellbore requiring a new ... the pipe, and the drilling rig itself. Categories Lost circulation falls into two main categories ... than 470 barrels 75 m sup 3 sup , or it takes greater than 48 hours to control or cease the lost circulation ... and the time involved in regaining circulation. Control Although preferred, ceasing lost circulation ... , which can lead to a blowout well drilling blowout . A number of options are available when lost circulation ... items in conjunction with, or followed by, a high viscosity fluid. If total losses occur and circulation ... if severe losses occur, as lost circulation can sometimes not be controlled with conventional or unconventional methods. Additives The most common additive used to control or cease lost circulation is bentonite ... of circulation, but can jeopardize the integrity of the wellbore itself. Additive Considerations Several ... more details
Image Gray22.png thumb Human embryo of 2.6 mm. Image Gray458.png thumb Diagram of the vascular channels in a human embryo of the second week. After Eternod. The red lines are the dorsal aort continued into the umbilical arteries . The red dotted lines are the ventral aort , and the blue dotted lines the vitelline veins . Vitelline circulation refers to the system of blood flowing from the embryo to the yolk sac and back again. The yolk sac is situated on the ventral aspect of the embryo it is lined by endoderm , outside of which is a layer of mesoderm . It is filled with fluid, the vitelline fluid , which possibly may be utilized for the nourishment of the embryo during the earlier stages of its existence. Blood is conveyed to the wall of the sac by the primitive aort , and after circulating through a wide meshed capillary plexus , is returned by the vitelline veins to the tubular heart of the embryo. This constitutes the vitelline circulation, and by means of it nutritive material is absorbed from the yolk sac and conveyed to the embryo. External links GrayPage 54 http www.med.umich.edu lrc coursepages M1 embryology embryo 13cardiovascular system.htm Overview of three circulation systems Gray s Category Cardiovascular system Category Embryology ... more details
Hyperdynamic circulation is abnormally increased circulatory volume. Systemic vasodilation and the associated decrease in peripheral vascular resistance results in decreased pulmonary capillary wedge pressure and decreased blood pressure , often presenting with a collapsing pulse . In effort to compensate the heart will increase cardiac output and heart rate , which accounts for the decreased pulse pressure and sinus tachycardia . ref Mosby s Medical Dictionary, 8th edition. S.v. hyperdynamic circulation. Retrieved July 28, 2010 from http medical dictionary.thefreedictionary.com hyperdynamic circulation ref The condition sometimes accompanies septic shock , preeclampsia , and other physiological and psychiatric conditions. Possible causes Renal disease Volume expansion Anemia Anxiety Arteriovenous fistula AV fistulae Beriberi Erythroderma Exercise Liver failure Hepatic failure Hydrocephalus ref Greitz, Dan. Radiological Assessment of hydrocephalus new theories and implications for therapy. Neurosurg Rev 2004 27 145 165. ref Hypercapnia Paget s disease Portal hypertension Pregnancy Pyrexia Thyrotoxicosis Vasodilator drugs References Reflist Category Cardiovascular diseases med stub ... more details
Multiple issues confusing August 2009 context August 2009 refimprove August 2009 Banknote s have a limited lifetime, after which they are collected for destruction, usually recycling or shredding . A banknote is removed from the money supply by bank s or other financial institution s due to everyday wear and tear from its handling. Banknote bundles are passed through a sorting machine that determines whether a particular note needs to be shredded, or are removed from the supply chain by a human inspector if they are deemed unfit for continued use for example, if they are mutilated or torn. Counterfeit banknotes are destroyed unless they are needed for evidentiary or forensic purposes. Contaminated banknotes are also decommissioned. A Canadian government report indicates Types of contaminant s include notes found on a corpse , stagnant water , contaminated by human or animal body fluid s such as urine, feces, vomit, infectious blood, fine hazardous powders from detonated explosives, dye pack and or drugs... These are removed from circulation primarily to prevent the spread of disease s. When taken out of circulation, Australia n bank notes are melted down and mixed together to form plastic garbage bin s. ref Singh, S.K. 2009 . Bank Regulations , Discovery Publishing House. ref Notes Reflist DEFAULTSORT Money Circulation Category Banknotes ... more details
, long considered to be an important anatomic vascular formation, provides backup circulation ... perfusion pressure External links http www.hemodynamic.com Computer Model of the Cerebral Circulation for Training and Education . http sky.bsd.uchicago.edu lcy ref synap brainblood.html Cerebral circulation ... more details
Image Illu pulmonary circuit.jpg thumb 400px Pulmonary circulation is the portion of the cardiovascular system which carries oxygen depleted blood away from the heart, to the lungs , and returns oxygenated blood back to the heart. The term is contrasted with systemic circulation . A separate system known as the bronchial circulation supplies blood to the tissue of the larger airways of the lung. Course Pulmonary circulation is the movement of blood from the heart, to the lungs, and back to the heart again. De oxygenated blood leaves the heart, goes to the lungs, and then re enters the heart oxygen poor blood leaves through the right ventricle through the pulmonary artery, the only artery in the body that carries oxygen poor blood, to the capillaries where carbon dioxide diffuses out of the blood cell into the alveoli, and oxygen diffuses out of the alveoli into the blood. Blood leaves the capillaries to the pulmonary vein, the only vein in the body that carries oxygen rich blood in the body, to the heart, where it re enters at the left ventricle. Right heart Oxygen depleted blood from the body leaves the systemic circulation when it enters the right heart , more specifically the right atrium through the superior vena cava superior upper vena cava and inferior vena cava inferior lower vena cava . The blood is then pumped through the tricuspid valve or right atrioventricular valve , into the right ventricle . Blood is then pumped through the semilunar valve and into the pulmonary artery . Arteries From the right ventricle , blood is pumped through the pulmonary semilunar valve into the left and right pulmonary arteries one for each lung and travels through the lungs . Lungs ... the systemic circulation before returning again to the pulmonary circulation. History Pulmonary circulation was first discovered and published by Ibn Nafis in his Commentary on Anatomy in Avicenna ... Harvey in 1616. Embryonic The pulmonary circulation loop is virtually bypassed in fetal circulation ... more details
The circulation problem and its variants is a generalisation of network flow problems, with the added constraint of a lower bound on edge flows, and with flow conservation also being required for the source and sink i.e. there are no special nodes . In variants of the problem, you have multiple commodities flowing through the network, and a cost on the flow. Definition Given is a flow network math G V,E math with math l v,w math , lower bound on flow from node math v math to node math w math , math u v,w math , upper bound on flow from node math v math to node math w math , math c v,w math , cost of a unit of flow on math v,w math and the constraints math l v,w leq f v,w leq u v,w math , math sum w in V f u,w 0 math flow cannot appear or disappear in nodes . Finding a flow assignment satisfying the constraints gives a solution to the given circulation problem. In the minimum cost variant of the problem, minimise math sum v,w in E c v,w cdot f v,w . math Multi commodity circulation In a multi commodity circulation problem, you also need to keep track of the flow of the individual commodities math ,f i v,w math The flow of commodity math i math from math v math to math w math . math ,f v,w sum i f i v,w math The total flow. The conservation constraint must be upheld for individually for the commodities math sum w in V f i u,w 0. math Solution For the circulation problem, many polynomial algorithms have been developed e.g., Edmonds Karp algorithm Edmonds and Karp , 1972 Tarjan 1987 1988 . which articles? For the case of multiple commodities, the problem is NP complete for integer flows ref name EIS76 cite journal author S. Even and A. Itai and A. Shamir title On the Complexity ... them with the general circulation setup given above. Minimum cost multi commodity circulation problem Using all constraints given above. Minimum cost circulation problem Use a single commodity Multi commodity circulation Solve without optimising cost. Simple circulation Just use one commodity, and no cost ... more details
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