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Khoja, Leila, Christy Mitchinson, Damien Brown, Cong Zhou, Karen Morris, Derek O'Reilly, Rahul Deshpande et al. "Pancreatic circulating tumor cells: Where are they?" Journal of Clinical Oncology 30, n. 15_suppl (20 maggio 2012): e21037-e21037. http://dx.doi.org/10.1200/jco.2012.30.15_suppl.e21037.
Testo completoAbstract (sommario):
e21037 Background: We previously demonstrated that circulating tumor cell (CTC) numbers in advanced pancreatic carcinoma were low in contrast to other epithelial carcinomas. We hypothesized that pancreatic CTCs may sequest in the liver and conceived a study to explore CTC number in the peripheral and portal circulations of patients undergoing Whipple’s surgery. Methods: Seventeen patients undergoing Whipple’s surgery were recruited prospectively after informed written consent. Blood was collected intra-operatively from the portal vein prior to tumor mobilization and from the peripheral circulation. Paired samples were analysed for CTC number (CellSearch system, Veridex, USA), and M30/M65 biomarkers of cell death. Results: Of 17 patients 6 had cholangiocarcinomas and 11 had pancreatic adenocarcinomas (5 inoperable). CTC number in the portal circulation was consistently higher than in the peripheral circulation. All patients with cholangiocarcinoma had no CTCs in the peripheral circulation but two patients had 139 and 21 CTCs in the portal circulation. Five patients with pancreatic carcinoma had no CTCs in the peripheral circulation but 1 CTC in 2 patients, 4 CTCs in 2 patients and 32 and 731 CTCs were seen in 2 other patients in the portal circulation. Five patients had no CTCs in both circulations and the remaining patient had 1 CTC in the peripheral circulation and 4 CTCs in the portal circulation. Where present, circulating tumour microemboli were detected in the portal circulation only. M65 levels were higher in the portal circulation indicating higher levels of cell death. M30 levels did not differ significantly between circulations but appeared to correlate with portal CTC number. Conclusions: This is the first study to enumerate CTCs in peripheral and portal circulations in pancreato-biliary carcinomas. Higher CTC numbers are present in the portal circulation suggesting CTC sequestration in the liver. Five patients with pancreatic cancer (2 of whom were inoperable) had no CTCs in either circulation, a finding consistent with the poor vascularity and dense stromal characteristics of this carcinoma. Nonetheless the portal circulation may be a potential source for CTC characterisation including genomic analysis to further define tumor biology.
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Miao, Yucong, Shuhua Liu, Yijia Zheng, Shu Wang e Bicheng Chen. "Numerical Study of the Effects of Topography and Urbanization on the Local Atmospheric Circulations over the Beijing-Tianjin-Hebei, China". Advances in Meteorology 2015 (2015): 1–16. http://dx.doi.org/10.1155/2015/397070.
Testo completoAbstract (sommario):
The effects of the topography and urbanization on the local atmospheric circulations over the Beijing-Tianjin-Hebei (BTH) region were studied by the weather research and forecasting (WRF) model, as well as the interactions among these local atmospheric circulations. It was found that, in the summer day time, the multiscale thermally induced local atmospheric circulations may exist and interact in the same time over the BTH region; the topography played a role in the strengthening of the sea breeze circulations; after sunset, the inland progress of sea breeze was slowed down by the opposite mountain breeze; when the land breeze circulation dominated the Bohai bay, the mountain breeze circulation can couple with the land breeze circulation to form a large circulation ranging from the coastline to the mountains. And the presence of cities cannot change the general state of the sea-land breeze (SLB) circulation and mountain-valley breeze (MVB) circulation but acted to modify these local circulations slightly. Meanwhile, the development of the urban heat island (UHI) circulation was also strongly influenced by the nearby SLB circulation and MVB circulation.
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Leete, Art, Elo-Hanna Seljamaa e Laur Vallikivi. "A Few Impressions and Reflections American Anthropological Association: 109th Annual Meeting. November 17–21, 2010. New Orleans". Folklore: Electronic Journal of Folklore 47 (2011): 185–90. http://dx.doi.org/10.7592/fejf2011.47.circulation.
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Plesca, Elina, Verena Grützun e Stefan A. Buehler. "How Robust Is the Weakening of the Pacific Walker Circulation in CMIP5 Idealized Transient Climate Simulations?" Journal of Climate 31, n. 1 (8 dicembre 2017): 81–97. http://dx.doi.org/10.1175/jcli-d-17-0151.1.
Testo completoAbstract (sommario):
Abstract The tropical overturning circulations are likely weakening under increased CO2 forcing. However, insufficient understanding of the circulations’ dynamics diminishes the full confidence in such a response. Based on a CMIP5 idealized climate experiment, this study investigates the changes in the Pacific Walker circulation under anthropogenic forcing and the sensitivity of its weakening response to internal variability, general circulation model (GCM) configuration, and indexing method. The sensitivity to internal variability is analyzed by using a 68-member ensemble of the MPI-ESM-LR model, and the influence of model physics is analyzed by using the 28-member CMIP5 ensemble. Three simple circulation indices—based on mean sea level pressure, 500-hPa vertical velocity, and 200-hPa velocity potential—are computed for each member of the two ensembles. The study uses the output of the CMIP5 idealized transient climate simulations with 1% yr−1 CO2 increase from preindustrial level, and investigates the detected circulation response until the moment of CO2 doubling (70 yr). Depending on the indexing method, it is found that 50%–93% of the MPI-ESM-LR and 54%–75% of the CMIP5 ensemble members project significant negative trends in the circulation’s intensity. This large spread in the ensembles reduces the confidence that a weakening circulation is a robust feature of climate change. Furthermore, the similar magnitude of the spread in both ensembles shows that the Walker circulation response is strongly influenced by natural variability, even over a 70-yr period.
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Jin, Xin, Shiru Huang e Xue Lei. "Research on the Impact Mechanism of Green Innovation in Marine Science and Technology Enabling Dual Economic Circulations". Sustainability 16, n. 19 (27 settembre 2024): 8421. http://dx.doi.org/10.3390/su16198421.
Testo completoAbstract (sommario):
Currently, accelerating the construction of a new development pattern with dual economic circulations is strategically significant for enhancing the autonomy and sustainability of China’s economic development. First of all, this paper, from the perspective of green innovation in marine science and technology, measures its efficiency using the SBM super-efficiency model. Then, a coupling coordination model calculates the coordination degree of dual economic circulations after measuring the domestic and international economic circulations based on the TOPSIS method. Secondly, a two-way fixed effects model is employed to examine the impact of green innovation in marine science and technology on domestic economic circulation, international economic circulation, and dual economic circulations. The study finds that green innovation in marine science and technology effectively promotes domestic economic circulation, international economic circulation, and the dual economic circulations. Additionally, green innovation in marine science and technology mitigates the impact of inter-regional resource misalignment on domestic economic circulation and influences international economic circulation by promoting the high-quality development of the marine economy. Finally, it is discovered that green innovation in marine science and technology exhibits a single-threshold heterogeneous effect on domestic economic circulation and international economic circulation.
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Waalewijn, R. A. "Problemen met de circulatie (C: Circulation)". Bijblijven 19, n. 7 (luglio 2003): 287–95. http://dx.doi.org/10.1007/bf03059727.
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Cunningham, Stuart A. "Southern Ocean circulation". Archives of Natural History 32, n. 2 (ottobre 2005): 265–80. http://dx.doi.org/10.3366/anh.2005.32.2.265.
Testo completoAbstract (sommario):
The Discovery Investigations of the 1930s provided a compelling description of the main elements of the Southern Ocean circulation. Over the intervening years, this has been extended to include ideas on ocean dynamics based on physical principles. In the modern description, the Southern Ocean has two main circulations that are intimately linked: a zonal (west-east) circumpolar circulation and a meridional (north-south) overturning circulation. The Antarctic Circumpolar Current transports around 140 million cubic metres per second west to east around Antarctica. This zonal circulation connects the Atlantic, Indian and Pacific Oceans, transferring and blending water masses and properties from one ocean basin to another. For the meridional circulation, a key feature is the ascent of waters from depths of around 2,000 metres north of the Antarctic Circumpolar Current to the surface south of the Current. In so doing, this circulation connects deep ocean layers directly to the atmosphere. The circumpolar zonal currents are not stable: meanders grow and separate, creating eddies and these eddies are critical to the dynamics of the Southern Ocean, linking the zonal circumpolar and meridional circulations. As a result of this connection, a global three-dimensional ocean circulation exists in which the Southern Ocean plays a central role in regulating the Earth's climate.
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Hickey, Joanne V. "Cerebral Circulation Demystified". AACN Advanced Critical Care 2, n. 4 (1 novembre 1991): 657–64. http://dx.doi.org/10.4037/15597768-1991-4005.
Testo completoAbstract (sommario):
Basic anatomic and physiologic concepts related to cerebral circulation are summarized. The arterial blood supply is traced from its origins to the major divisions of anterior and posterior circulation. The circle of Willis, the major arterial vessels and territories, and the peculiarities of the cerebral venous circulation are discussed. Finally, concepts of cerebral circulations are applied to clinical practice to assist the nurse in accurately assessing, monitoring, and predicting human responses to alterations in cerebral blood supply
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Lenz, T., G. D. James, J. H. Laragh e J. E. Sealey. "Prorenin secretion from human placenta perfused in vitro". American Journal of Physiology-Endocrinology and Metabolism 260, n. 6 (1 giugno 1991): E876—E882. http://dx.doi.org/10.1152/ajpendo.1991.260.6.e876.
Testo completoAbstract (sommario):
We examined whether renin (prorenin plus renin) is secreted from the human placenta into the maternal or fetal circulation and compared the secretion rate to that of human chorionic gonadotropin (hCG), progesterone, and estradiol. While estradiol and progesterone passed into both circulations, renin (mostly prorenin) and hCG were secreted predominantly into the maternal circulation. To examine if prorenin passed from the maternal to the fetal circulation and vice versa, we perfused both circuits separately with exogenous recombinant human prorenin. No prorenin passed from maternal to fetal circulations, but a small amount (less than 10%) slowly passed from fetal to maternal, beginning 15 min after the addition of prorenin. Exogenous prorenin was not converted to renin in either circulation. Perfusate total renin had close to 10% active renin, whereas that of tissue extracts was closer to 50%. In conclusion, the results are consistent with some tissue activation of prorenin, either in vitro or in vivo, but no activation in the maternal or fetal circulations. The human placenta may secrete prorenin into the maternal but not into the fetal circulation. The possibility that the placenta may secrete a small amount of active renin into the maternal circulation was not ruled out.
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Aquino-Martínez, Lourdes P., Arturo I. Quintanar, Carlos A. Ochoa-Moya, Erika Danaé López-Espinoza, David K. Adams e Aron Jazcilevich-Diamant. "Urban-Induced Changes on Local Circulation in Complex Terrain: Central Mexico Basin". Atmosphere 12, n. 7 (14 luglio 2021): 904. http://dx.doi.org/10.3390/atmos12070904.
Testo completoAbstract (sommario):
Land use land cover (LULC) significantly impacts local circulation in the Mexico Basin, particularly wind field circulations such as gap winds, convergence lines, and thermally induced upslope/downslope wind. A case study with a high-pressure system over the Mexico Basin isolates the influence of large-scale synoptic forcing. Numerical simulations reveal a wind system composed of meridional circulation and a zonal component. Thermal pressure gradients between the Mexico basin and its colder surroundings create near-surface convergence lines as part of the meridional circulation. Experiments show that the intensity and organization of meridional circulations and downslope winds increase when LULC changes from natural and cultivated land to urban. Zonal circulation exhibits a typical circulation pattern with the upslope flow and descending motion in the middle of the basin. Large values of moist static energy are near the surface where air parcels pick up energy from the surface either as fluxes of enthalpy or latent heat. Surface heat fluxes and stored energy in the ground are drivers of local circulation, which is more evident in zonal circulation patterns.
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Walker, Christopher C., e Tapio Schneider. "Eddy Influences on Hadley Circulations: Simulations with an Idealized GCM". Journal of the Atmospheric Sciences 63, n. 12 (dicembre 2006): 3333–50. http://dx.doi.org/10.1175/jas3821.1.
Testo completoAbstract (sommario):
An idealized GCM is used to investigate how the strength and meridional extent of the Hadley circulation depend on the planet radius, rotation rate, and thermal driving. Over wide parameter ranges, the strength and meridional extent of the Hadley circulation display clear scaling relations with regime transitions, which are not predicted by existing theories of axisymmetric Hadley circulations. For example, the scaling of the strength as a function of the radiative-equilibrium equator-to-pole temperature contrast exhibits a regime transition corresponding to a regime transition in scaling laws of baroclinic eddy fluxes. The scaling of the strength of the cross-equatorial Hadley cell as a function of the latitude of maximum radiative-equilibrium temperature exhibits a regime transition from a regime in which eddy momentum fluxes strongly influence the strength to a regime in which the influence of eddy momentum fluxes is weak. Over a wide range of flow parameters, albeit not always, the Hadley circulation strength is directly related to the eddy momentum flux divergence at the latitude of the streamfunction extremum. Simulations with hemispherically symmetric thermal driving span circulations with local Rossby numbers in the horizontal upper branch of the Hadley circulation between 0.1 and 0.8, indicating that neither nonlinear nearly inviscid theories, valid for Ro → 1, nor linear theories, valid for Ro → 0, of axisymmetric Hadley circulations can be expected to be generally adequate. Nonlinear theories of axisymmetric Hadley circulations may account for aspects of the circulation when the maximum radiative-equilibrium temperature is displaced sufficiently far away from the equator, which results in cross-equatorial Hadley cells with nearly angular momentum-conserving upper branches. The dependence of the Hadley circulation on eddy fluxes, which are themselves dependent on extratropical circulation characteristics such as meridional temperature gradients, suggests that tropical circulations depend on the extratropical climate.
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Ryu, Young-Hee, e Jong-Jin Baik. "Daytime Local Circulations and Their Interactions in the Seoul Metropolitan Area". Journal of Applied Meteorology and Climatology 52, n. 4 (aprile 2013): 784–801. http://dx.doi.org/10.1175/jamc-d-12-0157.1.
Testo completoAbstract (sommario):
AbstractDaytime local circulations and their interactions in the Seoul, South Korea, metropolitan area are investigated using a high-resolution mesoscale model. It is found that the urban-breeze circulation interacts strongly with other local circulations, such as sea-breeze, cross-valley, and river-breeze circulations. Inland penetration of the sea breeze is retarded in the morning when moving over the coastal urban area because of the increased surface roughness but is accelerated in the afternoon after passing through the urban area as a result of the landward-convergent flow induced by urban heat islands in the inland urban areas. In the valley region, the cross-valley circulation prevails in the morning and the urban-breeze circulation prevails in the afternoon. The mountainside urban-breeze circulation weakens because of the cross-valley circulation in the opposite direction. On the other hand, the plainside urban-breeze circulation away from the mountain increases in strength as a result of the combined effect of heating from the urban surface and subsidence heating associated with the cross-valley circulation. This strengthened urban breeze acts to inhibit penetration of the sea breeze farther inland, causing the sea breeze to stagnate in Seoul. In the vicinity of the Han River, convergence zones with strong updrafts are formed as a result of the interaction between the urban breeze and the river breeze. When the sea-breeze front encounters the strong updrafts, the vertical velocity of the front at the intersection points increases.
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Yokoyama, Chie, Edward J. Zipser e Chuntao Liu. "TRMM-Observed Shallow versus Deep Convection in the Eastern Pacific Related to Large-Scale Circulations in Reanalysis Datasets". Journal of Climate 27, n. 14 (10 luglio 2014): 5575–92. http://dx.doi.org/10.1175/jcli-d-13-00315.1.
Testo completoAbstract (sommario):
Abstract Over the eastern Pacific, recent studies have shown that a shallow large-scale meridional circulation with its return flow just above the boundary layer coexists with a deep Hadley circulation. This study examines how the vertical structure of large-scale circulations is related to satellite-observed individual precipitation properties over the eastern Pacific in boreal autumn. Three reanalysis datasets are used to describe differences in their behavior. The results are compared among reanalyses and three distinctly different convection periods, which are defined according to their radar echo depths. Shallow and deep circulations are shown to often coexist for each of the three periods, resulting in the multicell circulation structure. Deep (shallow) circulations preferentially appear in the mostly deep (shallow) convection period of radar echo depths. Thus, depth of convection basically corresponds to which circulation branch is dominant. This anticipated relationship between the circulation structure and depths of convection is common in all three reanalyses. Notable differences among reanalyses are found in the mid- to upper troposphere in either the time-mean state or the composite analysis based on the convection periods. Reanalyses have large variations in characteristics associated with deep circulations such as the upper-tropospheric divergence and outflows and the midlevel inflows, which are consistent with their different profiles of latent heating in the mid- to upper troposphere. On the other hand, discrepancies in shallow circulations and shallow convection are also found, but they are not as large as those in deep ones.
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Kim, Hye-Ryeom, Kyung-Ja Ha, Suyeon Moon, Hyoeun Oh e Sahil Sharma. "Impact of the Indo-Pacific Warm Pool on the Hadley, Walker, and Monsoon Circulations". Atmosphere 11, n. 10 (24 settembre 2020): 1030. http://dx.doi.org/10.3390/atmos11101030.
Testo completoAbstract (sommario):
The Indo-Pacific warm pool (IPWP) is enclosed by a 28 °C isotherm and plays a vital role in controlling atmospheric circulations. However, the effects of changes in regional warm pool sea surface temperatures (SSTs) remain unexplored. We divided the IPWP into the Indian and Pacific sectors and distinguished their responses to natural variability and global warming. Furthermore, we examined the impacts of the interannual variability (IAV) in warm pool SST on the tropical Hadley, Walker, and monsoon circulations. The Hadley circulation was affected by warm pool SST warming, i.e., warmer SSTs over the warm pool strengthened the upward branch of Hadley circulation, whereas the downward branch was respectively weakened and strengthened in the Northern and Southern Hemispheres. Walker circulation was strengthened (weakened) in the warming (natural) mode. Consequently, the Walker circulation is weakened since the natural variability of warm pool SST plays a more dominant role rather than the warming trend of SSTs over the warm pool. Furthermore, our analysis displays that warm pool warming has little impact on the monsoon circulation. Our findings highlight the different roles of the IAV of warm pool regions in each tropical circulation as part of the warming trend and natural variability.
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Wills, Robert C., Xavier J. Levine e Tapio Schneider. "Local Energetic Constraints on Walker Circulation Strength". Journal of the Atmospheric Sciences 74, n. 6 (22 maggio 2017): 1907–22. http://dx.doi.org/10.1175/jas-d-16-0219.1.
Testo completoAbstract (sommario):
Abstract The weakening of tropical overturning circulations is a robust response to global warming in climate models and observations. However, there remain open questions on the causes of this change and the extent to which this weakening affects individual circulation features such as the Walker circulation. The study presents idealized GCM simulations of a Walker circulation forced by prescribed ocean heat flux convergence in a slab ocean, where the longwave opacity of the atmosphere is varied to simulate a wide range of climates. The weakening of the Walker circulation with warming results from an increase in gross moist stability (GMS), a measure of the tropospheric moist static energy (MSE) stratification, which provides an effective static stability for tropical circulations. Baroclinic mode theory is used to determine changes in GMS in terms of the tropical-mean profiles of temperature and MSE. The GMS increases with warming, owing primarily to the rise in tropopause height, decreasing the sensitivity of the Walker circulation to zonally anomalous net energy input. In the absence of large changes in net energy input, this results in a rapid weakening of the Walker circulation with global warming.
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Endre Nagy, Tibor. "Human blood circulation model based on flow laws of intensity and continuity in relation to earth’s surface gravity". Journal of Lung, Pulmonary & Respiratory Research 10, n. 2 (8 giugno 2023): 46–54. http://dx.doi.org/10.15406/jlprr.2023.10.00301.
Testo completoAbstract (sommario):
With the help of the physical laws of flow, it is possible to describe the entire human blood circulation. However, this requires precise knowledge of the individual parameters. Within this, the determination of the flow rate included in the law of continuity is essential. Together with the data of the heart and circulation examination procedures, in order to establish the average human blood circulation, an intermediate velocity value must be selected, which is located in the middle between the two extreme velocities of the blood circulation. Another important factor from the point of view of the structure and operation of the model is the value of the earth's surface gravity. By finding the average flow speed value and using ‘g’, a torus-shaped circulation can be created, which can actually reflect the circulation conditions. By further refining the model, the pulmonary and systemic circulations can be separated and a ‘folded figure eight’ model can be formed. This realistically reflects the different sizes, flow and pressure conditions of the two blood circulations, as well as the work of the left and right sides of the heart.
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Wu, Yutian, e Olivier Pauluis. "Examination of Isentropic Circulation Response to a Doubling of Carbon Dioxide Using Statistical Transformed Eulerian Mean*". Journal of the Atmospheric Sciences 70, n. 6 (29 maggio 2013): 1649–67. http://dx.doi.org/10.1175/jas-d-12-0235.1.
Testo completoAbstract (sommario):
Abstract Responses of the atmospheric circulation to a doubling of CO2 are examined in a global climate model, focusing on the circulation on both dry and moist isentropes. The isentropic circulations are reconstructed using the statistical transformed Eulerian mean (STEM), which approximates the isentropic flow from the Eulerian-mean and second-order moments. This approach also makes it possible to decompose the changes in the circulation into changes in zonal mean and eddy statistics. It is found that, as a consequence of CO2 doubling, the dry isentropic circulation weakens across all latitudes. The weaker circulation in the tropics is a result of the reduction in mean meridional circulation while the reduction in eddy sensible heat flux largely contributes to the slowdown of the circulation in the midlatitudes. The heat transport on dry isentropes, however, increases in the tropics because of the increase in dry effective stratification whereas it decreases in the extratropics following the reduction in eddy sensible heat transport. Distinct features are found on moist isentropes. In the tropics, the circulation weakens, but without much change in heat transport. The extratropical circulation shifts poleward with an intensification (weakening) on the poleward (equatorward) flank, primarily because of the change in eddy latent heat transport. The total heat transport in the midlatitudes also shows a poleward shift but is of smaller magnitude. The differences between the dry and moist circulations reveal that in a warming world the increase in midlatitude eddy moisture transport is associated with an increase in warm moist air exported from the subtropics into the midlatitude storm tracks.
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French, Michael M., Howard B. Bluestein, David C. Dowell, Louis J. Wicker, Matthew R. Kramar e Andrew L. Pazmany. "High-Resolution, Mobile Doppler Radar Observations of Cyclic Mesocyclogenesis in a Supercell". Monthly Weather Review 136, n. 12 (1 dicembre 2008): 4997–5016. http://dx.doi.org/10.1175/2008mwr2407.1.
Testo completoAbstract (sommario):
Abstract On 15 May 2003, two ground-based, mobile, Doppler radars scanned a supercell that moved through the Texas Panhandle and cyclically produced mesocyclones. The two radars collected data from the storm during a rapid cyclic mesocyclogenesis stage and a more slowly evolving tornadic period. A 3-cm-wavelength radar scanned the supercell continuously for a short time after it was cyclic but close to the time of tornadogenesis. A 5-cm-wavelength radar scanned the supercell the entire time it exhibited cyclic behavior and for an additional 30 min after that. The volumetric data obtained with the 5-cm-wavelength radar allowed for the individual circulations to be analyzed at multiple levels in the supercell. Most of the circulations that eventually dissipated moved rearward with respect to storm motion and were located at distances progressively farther away from the region of rear-flank outflow. The circulations associated with a tornado did not move nearly as far rearward relative to the storm. The mean circulation diameters were approximately 1–4 km and had lifetimes of 10–30 min. Circulation dissipation often, but not always, occurred following decreases in circulation diameter, while changes in maximum radial wind shear were not reliable indicators of circulation dissipation. In one instance, a pair of circulations rotated cyclonically around, and moved toward, each other; the two circulations then combined to form one circulation. Single-Doppler radial velocities from both radars were used to assess the differences between the pretornadic circulations and the tornadic circulations. Storm outflow in the rear flank of the storm increased notably during the time cyclic mesocyclogenesis slowed and tornado formation commenced. Large storm-relative inflow likely advected the pretornadic circulations rearward in the absence of organized outflow. The development of strong outflow in the rear flank probably balanced the strong inflow, allowing the tornadic circulations to stay in areas rich in vertical vorticity generation.
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Fernández-Rodriguez, Conrado M., Ignacio R. Prada, Jesús Prieto, Luis M. Montuenga, Ted Elsasser, Jorge Quiroga, Mercedes Moreiras, Amalia Andrade e Frank Cuttitta. "Circulating adrenomedullin in cirrhosis: relationship to hyperdynamic circulation". Journal of Hepatology 29, n. 2 (agosto 1998): 250–56. http://dx.doi.org/10.1016/s0168-8278(98)80010-x.
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Wang, Yafei, Jianzhao Qin e Lijuan Zhu. "The Okhotsk-Japan Circulation Pattern and the Heavy Rainfall in Beijing in 2012 Summer". Advances in Meteorology 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/483970.
Testo completoAbstract (sommario):
Using station precipitation and reanalysis data, we examined the evolution of the large-scale circulations associated with the heavy rainfall event that occurred around July 21, 2012 (721 heavy rainfall). This study focuses on a role that the large-scale circulations named “the Okhotsk-Japan (OKJ) circulation pattern” played in causing the heavy rainfall case. We found that the 721 heavy rainfall occurred under a background of the OKJ circulation that persisted for about 10 days. However, the pattern was different from the normal OKJ circulation, for this circulation pattern accompanied a blocking high between the Ural Mountains and the Baikal Lake. This difference resulted from the seasonal change of the basic flow. The related Rossby wave propagated eastward during the persisting period of the dominated OKJ pattern. This caused the development of a low-pressure system around the Baikal Lake and the weakening of a ridge around the Okhotsk Sea. The slow evolution of the OKJ circulation created a favorable environment for the moisture transport to northern China, assisting in the generation of the 721 heavy rainfall.
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Jiang, Yunyan, Jinyuan Xin, Ying Wang, Guiqian Tang, Yuxin Zhao, Danjie Jia, Dandan Zhao et al. "The thermodynamic structures of the planetary boundary layer dominated by synoptic circulations and the regular effect on air pollution in Beijing". Atmospheric Chemistry and Physics 21, n. 8 (23 aprile 2021): 6111–28. http://dx.doi.org/10.5194/acp-21-6111-2021.
Testo completoAbstract (sommario):
Abstract. To investigate the impacts of multiscale circulations on the planetary boundary layer (PBL), we have carried out the PBL thermodynamic structure field experiment with a Doppler wind profile lidar, a microwave radiometer, and a ceilometer from January 2018 to December 2019 in Beijing. We found that the direct regulatory effect of synoptic circulation worked through transporting and accumulating pollutants in front of mountains in the daytime, while the indirect effect of multiscale circulations worked through coupling mechanisms in the nighttime. The horizontal coupling of different-direction winds produced a severe pollution convergent zone. The vertical coupling of upper environmental winds and lower regional breezes regulated the mixing and diffusion of pollutants by generating dynamic wind shear and advective temperature inversion. We also found that the dominating synoptic circulations led to great differences in PBL thermodynamic structure and pollution. The cyclonic circulation resulted in a typical multilayer PBL characterized by high vertical shear (600 m), temperature inversion (900 m), and an inhomogeneous stratification. Meanwhile, strong regional breezes pushed the pollution convergent zone to the south of Beijing. The southwesterly circulation resulted in a mono-layer PBL characterized by low vertical shear (400 m) and inversion (200 m). The westerly circulation led to a hybrid-structure PBL, and the advective inversion was generated by the vertical shear of zonal winds. Strong environmental winds of southwesterly and westerly circulations pushed the severe-pollution zone to the front of mountains. There was no distinct PBL structure under the anticyclone circulation. The study systematically revealed the appreciable effects of synoptic and regional circulations on PBL structure and air quality, which enriched the prediction theory of atmospheric pollution in the complex terrain.
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Pasquier, Benoît, Mark Holzer, Matthew A. Chamberlain, Richard J. Matear, Nathaniel L. Bindoff e François W. Primeau. "Optimal parameters for the ocean's nutrient, carbon, and oxygen cycles compensate for circulation biases but replumb the biological pump". Biogeosciences 20, n. 14 (26 luglio 2023): 2985–3009. http://dx.doi.org/10.5194/bg-20-2985-2023.
Testo completoAbstract (sommario):
Abstract. Accurate predictive modeling of the ocean's global carbon and oxygen cycles is challenging because of uncertainties in both biogeochemistry and ocean circulation. Advances over the last decade have made parameter optimization feasible, allowing models to better match observed biogeochemical fields. However, does fitting a biogeochemical model to observed tracers using a circulation with known biases robustly capture the inner workings of the biological pump? Here we embed a mechanistic model of the ocean's coupled nutrient, carbon, and oxygen cycles into two circulations for the current climate. To assess the effects of biases, one circulation (ACCESS-M) is derived from a climate model and the other from data assimilation of observations (OCIM2). We find that parameter optimization compensates for circulation biases at the expense of altering how the biological pump operates. Tracer observations constrain pump strength and regenerated inventories for both circulations, but ACCESS-M export production optimizes to twice that of OCIM2 to compensate for ACCESS-M having lower sequestration efficiencies driven by less efficient particle transfer and shorter residence times. Idealized simulations forcing complete Southern Ocean nutrient utilization show that the response of the optimized system is sensitive to the embedding circulation. In ACCESS-M, Southern Ocean nutrient and dissolved inorganic carbon (DIC) trapping is partially short circuited by unrealistically deep mixed layers. For both circulations, intense Southern Ocean production deoxygenates Southern-Ocean-sourced deep waters, muting the imprint of circulation biases on oxygen. Our findings highlight that the biological pump's plumbing needs careful assessment to predict the biogeochemical response to ecological changes, even when optimally matching observations.
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Kuznetsova, Daria, Thibaut Dauhut e Jean-Pierre Chaboureau. "The Three Atmospheric Circulations over the Indian Ocean and the Maritime Continent and Their Modulation by the Passage of the MJO". Journal of the Atmospheric Sciences 76, n. 2 (1 febbraio 2019): 517–31. http://dx.doi.org/10.1175/jas-d-18-0188.1.
Testo completoAbstract (sommario):
Abstract The passage of the Madden–Julian oscillation (MJO) over the Indian Ocean and the Maritime Continent is investigated during the episode of 23–30 November 2011. A Meso-NH convection-permitting simulation with a horizontal grid spacing of 4 km is examined. The simulation reproduces the MJO signal correctly, showing the eastward propagation of the primary rain activity. The atmospheric overturning is analyzed using the isentropic method, which separates the ascending air with high equivalent potential temperature from the subsiding air with low equivalent potential temperature. Three key circulations are found. The first two circulations are a tropospheric deep circulation spanning from the surface to an altitude of 14 km and an overshoot circulation within the tropical tropopause layer. As expected for circulations associated with deep convection, their intensities, as well as their diabatic tendencies, increase during the active phase of the MJO, while their entrainment rates decrease. The third circulation is characterized by a rising of air with low equivalent potential temperature in the lower free troposphere. The intensity of the circulation, as well as its depth, varies with the MJO activity. During the suppressed phase, this circulation is associated with a dry air intrusion from the subtropical region into the tropical band and shows a strong drying of the lower to middle troposphere.
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Yang, Xuanyuan, e Yifa Sheng. "Research on MMC Circulation Suppression Technology". Journal of Physics: Conference Series 2479, n. 1 (1 aprile 2023): 012058. http://dx.doi.org/10.1088/1742-6596/2479/1/012058.
Testo completoAbstract (sommario):
Abstract Modular multilevel converters (MMCs) are extensively used in flexible high-voltage DC transmission systems. As an important part of them, it plays an important role in the normal use of MMCs. The main additional loss in the system is generated by the second harmonic in the circulating current. By summarizing and comparing current circulation control strategies. Based on the current research status of circulation suppression, we prospect the research direction of the MMC circulating current suppression.
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Kriest, Iris, Paul Kähler, Wolfgang Koeve, Karin Kvale, Volkmar Sauerland e Andreas Oschlies. "One size fits all? Calibrating an ocean biogeochemistry model for different circulations". Biogeosciences 17, n. 12 (18 giugno 2020): 3057–82. http://dx.doi.org/10.5194/bg-17-3057-2020.
Testo completoAbstract (sommario):
Abstract. Global biogeochemical ocean models are often tuned to match the observed distributions and fluxes of inorganic and organic quantities. This tuning is typically carried out “by hand”. However, this rather subjective approach might not yield the best fit to observations, is closely linked to the circulation employed and is thus influenced by its specific features and even its faults. We here investigate the effect of model tuning, via objective optimisation, of one biogeochemical model of intermediate complexity when simulated in five different offline circulations. For each circulation, three of six model parameters have been adjusted to characteristic features of the respective circulation. The values of these three parameters – namely, the oxygen utilisation of remineralisation, the particle flux parameter and potential nitrogen fixation rate – correlate significantly with deep mixing and ideal age of North Atlantic Deep Water (NADW) and the outcrop area of Antarctic Intermediate Waters (AAIW) and Subantarctic Mode Water (SAMW) in the Southern Ocean. The clear relationship between these parameters and circulation characteristics, which can be easily diagnosed from global models, can provide guidance when tuning global biogeochemistry within any new circulation model. The results from 20 global cross-validation experiments show that parameter sets optimised for a specific circulation can be transferred between similar circulations without losing too much of the model's fit to observed quantities. When compared to model intercomparisons of subjectively tuned, global coupled biogeochemistry–circulation models, each with different circulation and/or biogeochemistry, our results show a much lower range of oxygen inventory, oxygen minimum zone (OMZ) volume and global biogeochemical fluxes. Export production depends to a large extent on the circulation applied, while deep particle flux is mostly determined by the particle flux parameter. Oxygen inventory, OMZ volume, primary production and fixed-nitrogen turnover depend more or less equally on both factors, with OMZ volume showing the highest sensitivity, and residual variability. These results show a beneficial effect of optimisation, even when a biogeochemical model is first optimised in a relatively coarse circulation and then transferred to a different finer-resolution circulation model.
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Suzuki, Nobuhiro. "On the physical mechanisms of the two-way coupling between a surface wave field and a circulation consisting of a roll and streak". Journal of Fluid Mechanics 881 (25 ottobre 2019): 906–50. http://dx.doi.org/10.1017/jfm.2019.752.
Testo completoAbstract (sommario):
The governing equations of a surface wave field and a coexisting roll–streak circulation typical of Langmuir circulations or submesoscale frontal circulations are derived to better describe their two-way interactions. The gradients and vertical velocities of the roll–streak circulation induce wave refraction, amplitude modulation and higher-order waves. These changes then produce wave–wave nonlinear forces and divergence of the wave-induced mass transport, both of which in turn affect the circulation. To accurately represent these processes, both a wave theory and a wave-averaged theory are developed without relying on any extrapolation, any spatiotemporal mapping or an approximation that treats the wave-induced mass divergence as being concentrated at the surface. This wave theory finds seven types of current-induced higher-order wave motions. It also determines the wave dynamics such as the governing equation of the wave action density valid in the presence of the complex circulation. The evolution of the wave action density is clearly affected by the upwelling or downwelling. The new wave-averaged theory presents the governing equations of the wave-averaged circulation which satisfies the wave-averaged mass conservation. This circulation is different from the circulation considered to satisfy the mass conservation in the Craik–Leibovich theory, and the difference becomes critical when the wave field evolves due to refraction. In this case, compared to the Craik–Leibovich theory, long waves are more important and also the rolls are more weakly forced.
27
Nagao, Shigeto. "Structures and Interactions of Quantum Particles Based on the Energy Circulation Theory". Reports in Advances of Physical Sciences 03, n. 01 (marzo 2019): 1950001. http://dx.doi.org/10.1142/s2424942419500014.
Testo completoAbstract (sommario):
Although the quark model is widely accepted, it is unknown what the origin of the electric charge of a quark is and why the charge magnitudes are fractional and different among the [Formula: see text] and [Formula: see text] quarks. Here we propose a novel scheme for quantum particles independent of quantum chromodynamics and quarks. We previously reported the energy circulation theory, in which the fundamental force works between antiparallel energy movements based on momentums, and forms an energy circulation. The electric charge is the momentum in the hidden dimension of an energy circulation in hidden–space dimensions. In this paper, we examine the interactions between energy circulations precisely covering the whole range of distance, and derive formulas for strong and weak nuclear interactions. The strong force is an inter-circulation interaction by the fundamental force. The weak interaction is an orthogonal separation of an energy circulation in space–space dimensions to two halves. A quantum particle consists of one or plural energy circulations in a unit space of radius of the lowest-frequency hidden dimension. We propose the respective compositions of energy circulations for major particles so that they as much conform to reported decays, spin and rest-mass values. This new model of particles provides potential solutions to unexplained issues from the Standard Model as follows: The new model presents the theoretical origin of the electric charge and its elementary charge. Because elementary components of hadrons are energy circulations instead of quarks, it is not required to introduce a fractional electric charge. A composition of elementary energy circulations for a quantum particle shows its electric charge and mass (rest energy) by the addition of those of elements. Furthermore, the model successfully exhibits strong and weak nuclear interactions as well as the electric force.
28
Lian, Yuchen, Adam P. Showman, Xianyu Tan e Yongyun Hu. "Influences of Internal Forcing on Atmospheric Circulations of Irradiated Giant Planets". Astrophysical Journal 928, n. 2 (1 aprile 2022): 166. http://dx.doi.org/10.3847/1538-4357/ac5598.
Testo completoAbstract (sommario):
Abstract Close-in giant planets with strong stellar irradiation show atmospheric circulation patterns with strong equatorial jets and global-scale stationary waves. So far, almost all modeling works on atmospheric circulations of such giant planets have mainly considered external radiation alone, without taking into account the role of internal heat fluxes or just treating it in very simplified ways. Here, we study atmospheric circulations of strongly irradiated giant planets by considering the effect of internal forcing, which is characterized by small-scale stochastic interior thermal perturbations, using a three-dimensional atmospheric general circulation model. We show that the perturbation-excited waves can largely modify atmospheric circulation patterns in the presence of relatively strong internal forcing. Specifically, our simulations demonstrate three circulation regimes: a superrotation regime, a midlatitude-jet regime, and a quasi-periodic oscillation regime, depending on the relative importance of external and internal forcings. It is also found that strong internal forcing can cause noticeable modifications of the thermal phase curves.
29
Ji, Shengxian, Fei Xiao, Guisheng Jie, Shan Gao e Jiamin Ye. "A Power Circulating Suppression Method for Parallel Transient Inverters with Instantaneous Phase Angle Compensation". Energies 17, n. 17 (1 settembre 2024): 4368. http://dx.doi.org/10.3390/en17174368.
Testo completoAbstract (sommario):
A unidirectional link is typically incorporated into the DC input side of an inverter to ensure the reliability and stability of the microgrid power supply. Due to impedance and control variations among inverters, circulating currents may rapidly arise during the operation of parallel transient inverters. Nonetheless, the unidirectional power circulating in a DC unidirectional link results in energy accumulation on the DC side, causing DC bus voltage pumping and affecting MGs’ operation safety and stability. This paper proposes a non-communication-based circulation suppression strategy to suppress power circulation in parallel transients based on the local information of inverters. First, a parallel transient is modeled, and the power circulation phenomenon and its influencing factors are analyzed. Then, the instantaneous power and absorbed active energy are calculated to adjust the phase of the inverter output voltage and suppress power circulation. Moreover, the output frequency is adjusted to balance the DC-side voltage of each inverter. Then, the stability of the parallel system after adding the circulation suppression control strategy is verified using the Lyapunov function method. Finally, simulation and experimental results verify the effectiveness of the proposed power circulation suppression strategy.
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Chung, Cheng-Ta, Chien-Hsun Wu e Yi-Hsuan Hung. "Effects of Electric Circulation on the Energy Efficiency of the Power Split e-CVT Hybrid Systems". Energies 11, n. 9 (5 settembre 2018): 2342. http://dx.doi.org/10.3390/en11092342.
Testo completoAbstract (sommario):
This paper aims at investigating the fundamental characteristics of energy efficiency for power split electronic-continuously-variable-transmission (e-CVT) hybrid systems under the operation of electric circulation, i.e., circulating part of the engine power through the generator and motor in form of electric energy to improve system efficiency as well as perform the continuously-variable-transmission (CVT) functionality. The relations of kinematics and energy conservation for each power component are constructed and analyzed to classify how the operating points of the engine in term of torque and rotational speed may vary under different degrees of electric circulation indicated by a parameter called ratio of circulating power. Thereby, power split e-CVT hybrid systems can be classified into three types: upward circulation, downward circulation, and neutral circulation. Accordingly, two power split e-CVT hybrid systems, one of input split type and the other of output split type, are selected to be analyzed regarding their operating characteristics and simulated on their performances of energy efficiency. As a result, the former is a type of downward circulation in favor of driving at low speed and high driving load, while the latter is a type of upward circulation with an advantage of driving at high speed and low driving load. Thereby, applying this analysis to investigate the effects of electric circulation on power split e-CVT systems may help the developers implement suitable energy management and control strategy in accordance with their corresponding operating characteristics of energy efficiency.
31
Pottroff, Christy L. "Circulation". Early American Studies: An Interdisciplinary Journal 16, n. 4 (2018): 621–27. http://dx.doi.org/10.1353/eam.2018.0026.
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Hartroft, W. S. "Circulation". Annals of the New York Academy of Sciences 111, n. 1 (15 dicembre 2006): 534–37. http://dx.doi.org/10.1111/j.1749-6632.1963.tb36993.x.
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Agathocleous, Tanya, e Jason R. Rudy. "Circulation". Victorian Literature and Culture 46, n. 3-4 (2018): 621–25. http://dx.doi.org/10.1017/s1060150318000402.
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Wear, Andrew. "Circulation". Lancet 364, n. 9437 (settembre 2004): 835. http://dx.doi.org/10.1016/s0140-6736(04)16962-6.
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Kountchev, Jordan. "Circulation". Lancet 364, n. 9448 (novembre 2004): 1856. http://dx.doi.org/10.1016/s0140-6736(04)17437-0.
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Galcerà-Tomás, J., J. A. Nuño ade la Rosa, P. Rodriguez, G. Seller, G. Torres, M. Brù, T. Garcia-Paredes et al. "Circulation". Intensive Care Medicine 18, S2 (ottobre 1992): S115—S116. http://dx.doi.org/10.1007/bf03216350.
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Sealy, Jon. "Circulation". Appalachian Heritage 46, n. 2 (2018): 88–102. http://dx.doi.org/10.1353/aph.2018.0008.
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Lee, Thomas N., e Leonard J. Pietrafesa. "Circulation". Progress in Oceanography 19, n. 3-4 (gennaio 1987): 267–312. http://dx.doi.org/10.1016/0079-6611(87)90011-5.
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Eff, Carine, e Isabelle Saint-Saëns. "liberté de circulation vs circulation libérale". Vacarme 41, n. 4 (2007): 84. http://dx.doi.org/10.3917/vaca.041.0084.
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Ronco, Claudio, e Rinaldo Bellomo. "Central Circulation, Peripheral Circulation and Recirculation". Blood Purification 15, n. 4-6 (1997): 334–45. http://dx.doi.org/10.1159/000170352.
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Ferrari, Raffaele, Louis-Philippe Nadeau, David P. Marshall, Lesley C. Allison e Helen L. Johnson. "A Model of the Ocean Overturning Circulation with Two Closed Basins and a Reentrant Channel". Journal of Physical Oceanography 47, n. 12 (dicembre 2017): 2887–906. http://dx.doi.org/10.1175/jpo-d-16-0223.1.
Testo completoAbstract (sommario):
AbstractZonally averaged models of the ocean overturning circulation miss important zonal exchanges of waters between the Atlantic and Indo-Pacific Oceans. A two-layer, two-basin model that accounts for these exchanges is introduced and suggests that in the present-day climate the overturning circulation is best described as the combination of three circulations: an adiabatic overturning circulation in the Atlantic Ocean associated with transformation of intermediate to deep waters in the north, a diabatic overturning circulation in the Indo-Pacific Ocean associated with transformation of abyssal to deep waters by mixing, and an interbasin circulation that exchanges waters geostrophically between the two oceans through the Southern Ocean. These results are supported both by theoretical analysis of the two-layer, two-basin model and by numerical simulations of a three-dimensional ocean model.
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Yang, Xingtuan, Yanfei Sun, Zhiyong Liu e Shengyao Jiang. "Natural Circulation Characteristics of a Symmetric Loop under Inclined Conditions". Science and Technology of Nuclear Installations 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/925760.
Testo completoAbstract (sommario):
Natural circulation is an important process for primary loops of some marine integrated reactors. The reactor works under inclined conditions when severe accidents happen to the ship. In this paper, to investigate the characteristics of natural circulation, experiments were conducted in a symmetric loop under the inclined angle of 0~45°. A CFD model was also set up to predict the behaviors of the loop beyond the experimental scope. Total circulation flow rate decreases with the increase of inclined angle. Meanwhile one circulation is depressed while the other is enhanced, and accordingly the disparity between the branch circulations arises and increases with the increase of inclined angle. Circulation only takes place in one branch circuit at large inclined angle. Also based on the CFD model, the influences of flow resistance distribution and loop configuration on natural circulation are predicted. The numerical results show that to design the loop with the configuration of big altitude difference and small width, it is favorable to reduce the influence of inclination; however too small loop width will cause severe reduction of circulation ability at large angle inclination.
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Heinrich, P., e X. Blanchard. "Simulation of Atmospheric Circulation over Tahiti and of Local Effects on the Transport of 210Pb". Monthly Weather Review 137, n. 6 (1 giugno 2009): 1863–80. http://dx.doi.org/10.1175/2008mwr2648.1.
Testo completoAbstract (sommario):
Abstract Atmospheric transport of the natural radionuclide 210Pb is simulated by a general circulation model (GCM) and calculated surface concentrations are compared with those recorded at the Tahiti station on a daily scale. Numerical results for 2006 show the underestimation of concentrations for most recorded peaks. The purpose of this paper is to explain the observed discrepancies, to evaluate the GCM physical parameterizations, and to determine by numerical means the concentrations at Tahiti for a pollutant circulating across the South Pacific Ocean. Three meteorological situations in 2006 are further analyzed. Circulation over Tahiti for these periods is simulated by a mesoscale meteorological model using four nested grids with resolutions ranging from 27 to 1 km. The calculated wind fields are validated by those observed at two stations on the northwest coast of Tahiti, which is exposed both to topography-induced vortices and to thermally driven local breezes. Atmospheric dispersion of an offshore plume is then calculated by a particle Lagrangian transport model, driven by the mesoscale model at 1- and 81-km resolutions, representing local and global circulations, respectively. Simulations at 1-km resolution show the complex atmospheric circulation over Tahiti, which results in a large spatial and temporal variability of 210Pb surface concentrations on an hourly scale. The impact of local circulation is, however, limited when daily averaged concentrations at the station are considered. Under the studied regimes, transport simulations at the two resolutions lead to similar daily averaged concentrations. The deficiencies of the GCM in simulating daily averaged 210Pb concentrations could be attributable to the deep convection parameterization.
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giusti, sandra. "closing remarks". Cardiology in the Young 14, S3 (ottobre 2004): 97. http://dx.doi.org/10.1017/s1047951104006675.
Testo completoAbstract (sommario):
in the 17th century, william harvey discovered the circulation of the blood, describing at this time the pumping function of the heart and the “in series” disposition of the pulmonary and systemic circulations. these concepts provided the foundation for the development of modern cardiac physiology. during the three centuries that followed the discovery of circulation, many scientists studied and expanded our knowledge of cardiac and pulmonary function. with the description of complex congenital cardiac diseases, in particular functionally univentricular hearts, and with the development of their palliative surgical treatment, we have uncovered another type of cardiac physiology. in these cases, the circulation of the blood is characterized by an “in parallel” disposition of the pulmonary and systemic circulations, with direct venous–arterial connections in the absence of one pumping ventricle.
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Kim, Dong Wan, e Sukyoung Lee. "The Role of Latent Heating Anomalies in Exciting the Summertime Eurasian Circulation Trend Pattern and High Surface Temperature". Journal of Climate 35, n. 2 (15 gennaio 2022): 801–14. http://dx.doi.org/10.1175/jcli-d-21-0392.1.
Testo completoAbstract (sommario):
Abstract Dynamical mechanisms for the summer Eurasian circulation trend pattern are investigated by analyzing reanalysis data and conducting numerical model simulations. The daily circulations that resemble the Eurasian circulation trend pattern are identified and categorized into two groups based on surface warming signal over central and eastern Europe. In the group with large warm anomaly, the upper-level circulation takes on a wave packet form over Eurasia, and there are enhanced latent heating anomalies centered over the North Sea and suppressed latent heating anomalies over the Caspian Sea. The numerical model calculations indicate that these latent heating anomalies can excite an upper-level circulation response that resembles the Eurasian circulation trend pattern. Additional analysis indicates that trends of these two latent heating centers contribute to the long-term circulation trend. In the weak warm anomaly group, the circulation pattern takes on a circumglobal teleconnection (CGT) pattern, and there is no heating signal that reinforces the circulation. These results indicate that not all CGT-like patterns excite temperature anomalies that are persistent and in phase with the trend pattern, and that quasi-stationary forcings, such as the latent heating anomalies, play an important role in driving the boreal summer circulation anomaly that accompanies the strong and persistent surface temperature signal.
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Kelly, L., J. Kolbe, W. Mitzner, E. W. Spannhake, B. Bromberger-Barnea e H. Menkes. "Bronchial blood flow affects recovery from constriction in dog lung periphery". Journal of Applied Physiology 60, n. 6 (1 giugno 1986): 1954–59. http://dx.doi.org/10.1152/jappl.1986.60.6.1954.
Testo completoAbstract (sommario):
We investigated the effect of eliminating the bronchial circulation on recovery time from intravenous histamine challenge in canine lung periphery. Results from animals with intact bronchial circulations were compared with a second group in which the left lower lobe was isolated in situ. The pulmonary artery to this lobe was perfused and a bronchoscope was wedged in a small airway, which provided an index of resistance to airflow through the collateral system. The lobe was challenged with intravenous histamine, and the time constant of recovery (tau) from bronchoconstriction was measured. With or without pulmonary blood flow, elimination of the bronchial circulation increased tau 44.4 and 48.5%, respectively. This increase was similar to that found by stopping pulmonary blood flow alone (56.5%). Histamine challenges were also performed in sympathectomized or vagotomized animals with intact bronchial circulations. Neither of these conditions increased tau. We conclude that blood flow through the bronchial circulation affects the recovery time from intravenous histamine challenge in the lung periphery to a degree similar to that of the pulmonary circulation.
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Baerg, Bryan M., William P. Gargan, Ariel E. Cohen, Richard L. Thompson, Bryan T. Smith, Alan E. Gerard, Chauncy J. Schultz, Lawrence A. Kelly e Heather V. Nepaul. "Radar-Based, Storm-Scale Circulation and Tornado-Probability Tendencies Preceding Tornadogenesis in Kansas and Nebraska". E-Journal of Severe Storms Meteorology 15, n. 3 (5 ottobre 2021): 1–23. http://dx.doi.org/10.55599/ejssm.v15i3.77.
Testo completoAbstract (sommario):
This study analyzes the behavior of storm-scale circulations preceding initial tornadogenesis in 179 Kansas and Nebraska storms. Manually determined assessments of radar data for storm-scale circulations preceding the tornadoes are performed as far back in time prior to the tornado as a circulation is apparent, with average rotational velocity (Vrot), circulation diameter, and circulation clarity documented for the 0.5° elevation scan. These data are simultaneously combined with an indication of environmental conditions (as represented by the significant tornado parameter) to determine the tornado probability at each of these times based on a recently developed probabilistic model. By aggregating these parameters in time-range bins, subsequent statistical analyses portray the bulk variability of circulation characteristics and tornado probabilities preceding tornadogenesis. The blended approach for assessing tornado potential yields a stronger relative increase in tornado probabilities leading up to tornadogenesis than the sub-component of average Vrot; this is especially true within 15 min before tornadogenesis. Additionally, significant tornadoes are associated with more substantial increase in tornado probabilities preceding tornadogenesis compared to weak tornadoes, and smaller lead time to tornadogenesis for weak tornadoes. Also, a cycling pattern may appear in velocities prior to significant tornadoes, along with a relative decrease in pretornadic circulation diameter, especially for significant tornadoes. These findings are intended to highlight some of the behaviors of storm-scale circulations and their corresponding environments, which can be used to reinforce meteorologists’ tornado threat assessment. Extending this work to encompass more convective-mode variability, null cases, and geographic expanse will be necessary for more overarching applicability.
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Guo, Anboyu, John C. Moore e Duoying Ji. "Tropical atmospheric circulation response to the G1 sunshade geoengineering radiative forcing experiment". Atmospheric Chemistry and Physics 18, n. 12 (20 giugno 2018): 8689–706. http://dx.doi.org/10.5194/acp-18-8689-2018.
Testo completoAbstract (sommario):
Abstract. We investigate the multi-Earth system model response of the Walker circulation and Hadley circulations under the idealized solar radiation management scenario (G1) and under abrupt4xCO2. The Walker circulation multi-model ensemble mean shows changes in some regions but no significant change in intensity under G1, while it shows a 4∘ eastward movement and 1.9 × 109 kg s−1 intensity decrease in abrupt4xCO2. Variation in the Walker circulation intensity has the same high correlation with sea surface temperature gradient between the eastern and western Pacific under both G1 and abrupt4xCO2. The Hadley circulation shows significant differences in behavior between G1 and abrupt4xCO2, with intensity reductions in the seasonal maximum northern and southern cells under G1 correlated with equatorward motion of the Intertropical Convergence Zone (ITCZ). Southern and northern cells have a significantly different response, especially under abrupt4xCO2 when impacts on the southern Ferrel cell are particularly clear. The southern cell is about 3 % stronger under abrupt4xCO2 in July, August and September than under piControl, while the northern is reduced by 2 % in January, February and March. Both circulations are reduced under G1. There are significant relationships between northern cell intensity and land temperatures, but not for the southern cell. Changes in the meridional temperature gradients account for changes in Hadley intensity better than changes in static stability in G1 and especially in abrupt4xCO2. The difference in the response of the zonal Walker circulation and the meridional Hadley circulations under the idealized forcings may be driven by the zonal symmetric relative cooling of the tropics under G1.
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Hernandez, Edmée Sofia, e Carol Anne Germain. "Circulating a Good Service Model at Its Core: Circulation!" Public Services Quarterly 5, n. 2 (26 maggio 2009): 143–47. http://dx.doi.org/10.1080/15228950902851583.
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Vorontsov, V. V., M. N. Shakhova e S. V. Butova. "Development of process for obtaining crystalline food products with improved granulometric composition". IOP Conference Series: Earth and Environmental Science 1052, n. 1 (1 luglio 2022): 012098. http://dx.doi.org/10.1088/1755-1315/1052/1/012098.
Testo completoAbstract (sommario):
Abstract The subject of this research is the process of isohydric crystallization of mass from solution in a circulating crystallizer with the ability to control the size of food crystals. The developed design of a continuous circulation crystallizer provides the opportunity to adjust the circulation rate and meet temperature conditions. The functions of the solution particles and solid phase distribution over the time of residence in the crystallizer filled with a circulating suspension are found for the modes of ideal mixing and displacement determined by the circulation ratio of the suspension in the apparatus. The ability to control solution supersaturation and the time of suspension particles residence in the apparatus enables to obtain large production crystals.