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Hartley, S. A. "ATP regulated ion channels in arterial smooth muscle cells." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298264.
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Eid, Basma. "The pharmacology & therapeutic potential of Kv7 channels in the pulmonary circulation." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/the-pharmacology--therapeutic-potential-of-kv7-channels-in-the-pulmonary-circulation(6a9bb4a3-eb2a-4135-91b2-ca598f041f86).html.
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Pulmonary arterial tone is regulated in part by the membrane potential (Em) of pulmonary artery smooth muscle cells (PASMCs). The Kv7 family of K+ channels was recently implicated in regulating Em in rat PASMCs and expression of KCNQ1, KCNQ4 and KCNQ5 mRNA, which encode Kv7 channels, was reported. Kv7 activators were beneficial in two-independent mouse models of pulmonary hypertension (PH), which provides further evidence for their role in regulating pulmonary tone. The goals of this study were to: 1) Elucidate the role of Kv7 channels and Em in the hypertensive pulmonary circulation and 2) Study the effects and mechanism of action of a novel Kv7 modulator, zinc pyrithione (ZnPy) on the pulmonary circulation. PH was induced in male Wistar rats by administering a single 60 µg/kg intraperitoneal injection of monocrotaline (MCT). The effects of Kv7 modulators on hypertensive and control pulmonary arteries (PA) were compared using small-vessel myography. The vasoconstrictor effect of the Kv7 blocker, XE991, was enhanced in MCT PA. The Kv7 activators retigabine and ZnPy showed enhanced efficacy in relaxing MCT PA and suppressed raised intrinsic tone identified in MCT PA relative to control PA. The effects of MCT in responses to Kv7 modulators were pulmonary specific as they were not seen in mesenteric arteries from the same animals. Real-time PCR studies revealed that PA from MCT and control rats showed a similar expression of KCNQ1, KCNQ4 and KCNQ5 mRNA transcripts. I propose that the enhanced effects of Kv7 modulators on PA from MCT rats were due to disease-induced depolarization of PASMCs, which raised intrinsic tone and increased Kv7 channel activation at rest. This is the first evidence that Kv7 channels are functional in this model of PH and may serve as potential drug targets. The effects of ZnPy on PASMCs were studied by patch-clamp electrophysiology. ZnPy consistently hyperpolarized PASMCs and significantly increased the K+ current elicited by a voltage-step from -80 to +40 mV. ZnPy also increased the non-inactivating current recorded at 0 mV in some cells. The effects of ZnPy on Em and K+ currents were inhibited by 10 mM tetraethylammonium (TEA) and 1 µM paxilline but not by 50 nM iberiotoxin. XE991 (10µM) inhibited the ZnPy-induced hyperpolarization without altering its effects on K+ currents, suggesting that the current recorded was not responsible for its effect on Em. When tested on intact vessels, ZnPy consistently produced vasodilation. Its effects were unaffected by TEA, paxilline and iberiotoxin; however, XE991 (100 nM) had an inhibitory effect. The results suggest that ZnPy hyperpolarizes PASMCs by activating a TEA, paxilline and XE991 sensitive, but iberiotoxin insensitive channel, most likely a Kv7 channel. Its ability to dilate PA depended on pharmacologically distinct mechanisms, which are unlikely to involve Kv7 channels.
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Гуренко, Ірина Вікторівна, Наталя Євгеніївна Твердохлєбова, and Євгеній Олександрович Семенов. "Циркуляційні окислювальні канали." Thesis, НТУ "ХПІ", 2012. http://repository.kpi.kharkov.ua/handle/KhPI-Press/29749.
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Головною причиною загострення проблеми забезпечення населення питною водою є зростання антропогенного навантаження на водні ресурси в результаті інтенсивного хімічного, біологічного та радіаційного забруднення джерел питного водопостачання. Окислювальні канали економічні і представляють великий практичний інтерес для очищення стічних вод невеликих міст, селищ міського типу і окремих підприємств.The main reason for the aggravation of the problem of providing drinking water is growing anthropogenic pressure on water resources as a result of intensive chemical, biological and radioactive contamination of drinking water sources. Oxidation and economic channels are of great practical interest for wastewater treatment of small towns, townships and individual enterprises.
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Damm, Martin. "Mechanismen der hyperkapnieinduzierten Koronardilatation am isolierten Mausherz." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1219159555517-07583.
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Eine optimale Regulation der Koronardurchblutung ist für die Aufrechterhaltung der kardialen Pumpfunktion und damit der systemischen Perfusion von größter Bedeutung. Da Einschränkungen der Durchblutungszunahme des Herzmuskels Einschränkungen des maximalen myokardialen Sauerstoffverbrauchs und damit der Herzleistung zur Folge haben, ist es notwendig, die Koronardurchblutung kurzfristig an die jeweilige Stoffwechsellage des Herzens anzupassen (metabolische Koronarflussregulation). Die lokal-metabolischen Mechanismen gehören zu den wirksamsten Komponenten der Regulation der myokardialen Durchblutung und funktionieren auch am isolierten (denervierten) Herz. Dabei ist die hyperkapnie- und azidoseinduzierte Koronardilatation ein wesentlicher Bestandteil der metabolischen Koronarflussregulation. Die vorliegende Arbeit befasst sich mit der Hypothese der Abhängikeit der hyperkapnieinduzierten Koronardilatation von einer intakten NO-Produktion. Das Koronarsystem des isolierten WT-Mausherzens reagiert auf akute Hyperkapnie (91 % O2, 9 % CO2) mit einer deutlichen Koronarflusssteigerung von ca. 35 % über dem Basalfluss.Es konnte gezeigt werden das Stickstoffmonoxid (NO) und ATP-abhängige Kaliumkanäle (K+ATP-Kanäle) für die Koronarflussregulation der Maus eine ausschlagebende Rolle spielen und neben der Aufrechterhaltung des Basalflusses auch an der Vermittlung der hyperkapnieinduzierten Koronardilatation maßgeblich beteiligt sind.Interessanterweise ist bei einem Fehlen der endothelialen NO-Synthase durch genetischen Knockout die hyperkapnieinduzierte Flussantwort in Kinetik und Ausmaß vollständig erhalten. Die Vermittlung kann dabei durch andere Mechanismen kompensiert werden, wie zum Beispiel einer verstärkten Aktivität der K+ATP-Kanäle. Prostaglandine und neuronale NO-Synthase scheinen sowohl beim Wildtypherzen als auch bei Herzen mit fehlender NO-Synthase für die hyperkapnieinduzierte Koronardilatation von untergeordneter Bedeutung. Nach chronischer pharmakologischer Blockade der NO-Synthase durch zweiwöchige L-NAME Tränkung bleibt die hyperkapnieinduzierte Koronardilatation erhalten durch NOS-unabhängige Mechanismen. Die hyperkapnieinduzierte Flussantwort ist bei Herzen von weiblichen eNOSKO Tieren vorhanden, erscheint jedoch gegenüber den männlichen Mäusen geringer ausgeprägt. Daher wird vermutet, dass die Mediatorsysteme der endothelabhängigen Koronarflussregulation geschlechtsspezifisch bzw. geschlechtsabhängig sind.
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Négrel, Nathalie. "Circulations transnationales des discours télévisuels : TV5 Monde, France 24 et les migrations subsahariennes." Thesis, Toulouse 2, 2015. http://www.theses.fr/2015TOU20049.
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Cette recherche questionne la configuration spécifique des chaînes internationales de télévision, à travers deux cas précis, ceux de TV5 Monde et France 24. La focalisation sur ces deux acteurs médiatiques nous permet d’interroger de manière concrète et empirique la circulation transnationale des contenus télévisuels. En outre, nous avons choisi de questionner la production des contenus au sein de ces chaînes en nous concentrant sur un thème qui se trouve au cœur des réflexions sur la « globalisation » et les postcolonial studies, les migrations subsahariennes. Afin de questionner les spécificités des chaînes de télévision internationales et la manière dont celles-ci se traduisent au sein des Rédactions, nous articulons l’analyse de trois types de discours : 1) Nous étudions d’une part les discours institutionnels présidant à la gouvernance des chaînes à travers les nombreux rapports politiques, ainsi que les documents communicationnels diffusés par les deux chaînes. 2) Dans l’objectif d’interroger de manière concrète la production de contenus, nous analysons également les programmations de TV5 Monde et France 24 en nous focalisant sur les émissions diffusées entre 2006 et 2010 et qui portent sur les migrations subsahariennes. 3) Les entretiens compréhensifs que nous avons menés avec les journalistes permettent alors de saisir les différentes médiations qui interviennent au sein des deux chaînes (médiations techniques, individuelles, hiérarchiques, politiques, économiques…) et qui conditionnent cette configuration de la circulation des discours télévisuelsThis research analyses the specific configuration of international television channels from two case studies, TV5 Monde and France 24. Focusing on these two media actors allows us to empirically interrogate the transnational circulation of television contents. Furthermore, we have chosen to analyse the content production of these two television channels through the theme of the Sub-Saharan migrations, which finds itself at the heart of globalisation studies and postcolonial studies. In order to examine the specificities of the international television channels and the way they manifest themselves in the newsrooms, we articulate the analysis of three types of discourses: 1) On the one hand, we study the institutional discourses presiding over the governance of the television channels by analysing numerous political reports as well as communication documents distributed by the two television channels. 2) In order to observe the content production in a concrete way, we analyse, on the other hand, the programs of the two channels, TV5 Monde and France 24, focusing more precisely on the shows on the Sub-Saharan migrations broadcast between 2006 and 2010. 3) Finally, the comprehensive interviews that we have conducted with journalists are helpful to understand the different mediations that occur in the two television channels (technological, individual, hierarchical, political, economic mediations...) and how they influence the configuration of the circulation of television discourses
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Wadley, Martin Robert. "Modelling the bottom water circulation in the Vema Channel." Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.482778.
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Musiak, Jeffery Daniel. "Three-dimensional circulation dynamics of along-channel flow in stratified estuaries /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/6823.
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Qin, Qubin. "A Study of Vertical Patterns and Mechanisms of Along-Channel Estuarine Circulation." W&M ScholarWorks, 2012. https://scholarworks.wm.edu/etd/1539617913.
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The classical theory of estuarine dynamics has been challenged by a number of recent studies regarding the important contributions of tidal, lateral, and Coriolis effects to the subtidal dynamics at leading order. Although the classical theory excluded these processes, Hansen and Rattray’ ( R65) b subtidal circulation. However, the success of the predictive skill is not well understood. In this thesis, a perturbation approach is introduced to derive a “ ” (GS) of subtidal along-channel velocity profile for estuarine circulation incorporating the effects of tidal and lateral processes, which allows us to evaluate the possible circulation patterns, the underlying mechanisms, and to diagnose the contributions of these nonlinear processes. The GS applies to the entire estuary at any location without including presumptions of constant baroclinic pressure gradient and constant eddy viscosity. The GS was tested against a numerical model simulation case. A non-dimensional parameter is introduced for determining the structure of estuarine circulation. The success of HR65 has been evaluated and compared with GS. It is found that HR65 is a particular case of GS when estuarine circulation is dominated by horizontal pressure gradients and it has a good predictive skill when X is in the range between -0.53 and -0.20. However, its scaling of the strength of estuarine circulation could deviate from the true circulation when these nonlinear effects are important unless this scaling or its dependence on constant eddy viscosity is rectified by a scaling factor Y .
GS can be considered as the superimposition of flow uc that is only related to depth-averaged velocity C and exchange flow ur. The exchange flow consists of six possible patterns. Four of them have two-layer structure, and the remaining two have xii three-layer structure. The pattern of the estuarine circulations will be altered and some patterns cannot be observed when the magnitude of C is comparable to exchange flow. The circulation exhibits a total inflow (or outflow) when C is much large than exchange flow. The typical pattern of circulation is the two-layer circulation with seaward flow in the upper layer and landward flow in the lower layer. Both the lateral processes and tides could significantly change the pattern through its effect on mixing and barotropic forcing.
Although terms higher than 4th-order can reduce the deviation of model results from the real circulation, their inclusion does not have clear physical meaning. Therefore, the general solution only retains a 4th-order approximation of the circulation that can explain both two-layer and three-layer circulation patterns being observed in estuaries.
Besides the density-driven circulation, other possible circulations such as tideinduced and laterally-induced circulation are discussed. It is found that they could create two-layer circulation that has structure similar to observations. However, the results suggest that baroclinic forcing is the primary fundamental mechanism of estuarine circulation.
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Walicka, Kamila. "Impacts of basin-scale forcing on the circulation of the Faroe-Shetland Channel." Thesis, University of Aberdeen, 2019. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=240735.
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The investigation of the role of basin-scale forcing on the circulation of the Faroe-Shetland Channel (FSC) is important to further understanding of the inter-annual variability of the Atlantic water (AW) fluxes in this region. The FSC plays a key role in the transfer of warm and saline AW towards the Nordic Seas that is an integral part of the Atlantic Meridional Overturning Circulation which is projected to decline over the twenty-first century and might reduce the oceanic heat and salt transports towards the Arctic. So far little attention has been paid to the mechanisms driving the AW fluxes in the FSC, reliable estimates of AW temperature and salt transports time series are lacking. This study presents a new time series of the AW fluxes based on the combination of hydrography and altimetry data. The mechanisms involved in driving the variability of AW fluxes are considered based on observational data and the output from a high-resolution ocean model (VIKING20). The hydrographic observations from 1993 to 2015 show an increase in temperature and salinity of AW. However, there is no evidence of trends in AW volume, temperature or salt transports during the observed period. This analysis confirms that the amount of heat and salt transported through the FSC is dominated by the volume transport. Moreover, this study identifies a bias in the standard deviation of the geostrophic velocity at a depth associated with referencing the geostrophic calculations to the sea surface geostrophic velocity from satellite altimetry. This finding does not strongly influence the AW volume transports in the AW layer, however, it has important implications for estimates of the geostrophic volume transport at depth. This study shows that the Ekman driven up/downwelling and the differential Ekman pumping mechanisms driven by the local wind forcing may influence sea surface height (SSH) and the displacement of isopycnals in the channel, leading to AW volume transport variabilit However, due to the large associated error bars on the surface and subsurface parameters, there is no clear evidence that these mechanisms are significantly responsible for the AW volume transport variability in the FSC. Lagrangian trajectories show evidence of two pathways from the North Atlantic to the FSC that may explain AW variability in the FSC: one pathway involves the flow of warm and saline waters from the Rockall Trough that corresponds to high temperatures and low AW volume transport in the channel, and the other pathway involves the flow of relatively cooler and less saline waters from the Iceland Basin that is linked to low temperatures and stronger volume transport in the FSC. Moreover, we show that the first (second) pathway is associated with the negative (positive) phases of the North Atlantic Oscillation (NAO) and the ocean gyre contraction (expansion). The changes of the NAO index phases explain 26 % of the AW volume transport variance in the FSC. Another important mechanism that leads to stronger (weaker) AW volume transport is stronger (weaker) pressure gradient across the Greenland-Scotland Ridge, reflected by the SSH changes. This mechanism explains 29 % of AW volume transport variance in the FSC.
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Sangweni, Lucy Sithombesethu. "Experimental and numerical modelling investigations of the response of a two-phase natural circulation multi-parallel channel system." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97140.
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Thesis (MEng)--Stellenbosch University, 2015.ENGLISH ABSTRACT: In the present study, two-phase natural circulation flow in a multi-parallel channel system was investigated using experimental and numerical modelling. The investigation was carried out under different power excitations and various system operations (open system, closed system and heat pipe mode). The multichannel system was equipped at the upper end with a condenser enclosed within a steam drum, while the lower portion of each channel was heated to heat the system. For the numerical modelling, transient one-dimensional conservation equations were derived from first principle for both single- and two-phase fluids and used to computer program the system’s discretised simulation model. Temperatures and mass flow rates of the fluid responses as a result of different power excitations and operations were obtained for both the experimental and numerical modelling. It was observed from the results that the fluid experiences a start-up transient before accomplishing steady-state conditions. It was further noted that the transient duration varies with power excitations and system operation modes and hence with the stability of the system. A rise in power proved not to necessarily increase the fluid mass flow rate, but invited oscillations with higher amplitudes, depending on the system’s mode of operation. Type I instability and low-quality steam oscillations were witnessed at low power and open system operation mode (system open to the atmosphere). Type II instabilities and flashing instability were observed to be associated with medium and high-power excitations for the open system mode of operation. The fluid flow became more stable and less oscillatory at all power excitations for the closed system operation mode (system not open to the atmosphere). However, a sub-cooling effect was evident at higher power, where the two-phase fluid temperatures oscillated in a sinusoidal manner. However, the mass flow rates oscillated with high amplitudes in the forward direction in some channels and assumed a unidirectional flow in other channels. In general, steady-state conditions were obtained earlier when the system was operated as a closed system. For the heat pipe mode of operation, the system transient response in all channels exhibited a geysering instability followed by flashing-induced boiling. In-phase (flow in channels exhibiting the same behaviour) and out-of-phase (flow in channels exhibiting contradictory conduct) behaviour between adjacent channels were observed at all power excitations and system operation modes. Flow reversal in heated channels of a natural circulation system were proven to exists even under equal power excitations.
AFRIKAANSE OPSOMMING: In hierdie studie is tweefasige natuurlike sirkulasievloei in ’n parallelle multikanaalstelsel ondersoek deur middel van eksperimentele en numeriese modellering. Die ondersoek is onder verskillende kragopwekkings en verskeie stelselwerkings (oop stelsel, toe stelsel en hittepypmodus). Die multikanaalstelsel is aan die bopunt met ’n kondensor binne ’n stoomdrom toegerus, terwyl die laer gedeelte van elke kanaal verhit is om die stelsel te verhit. Vir die numeriese modellering, is oorgangseendimensionele behoundsvergelykings vanaf die eerste beginsel vir beide een- en tweefasige vloeistowwe afgelei en dit is gebruik om die stelsel se gediskretiseerde simulasiemodel vir ’n rekenaar te programmeer. Temperature en massavloeitempo’s van die vloeistofrespons as gevolg van verskillende kragopwekkings en -werkings is vir beide die eksperimentele en die numeriese modellering verkry. Dit is in die resultate waargeneem dat die vloeistof ’n aansitoorgang ervaar voor dit vloeiewewigstoestande bereik. Daar is verder waargeneem dat die duur van die oorgang wissel volgens kragopwekkings en stelselwerkingsmodusse en dus op grond van die stabiliteit van die stelsel. ’n Toename in krag het nie noodwendig die vloeitempo van die vloeistofmassa verhoog nie, maar het aanleiding gegee tot ossillasies met groter amplitudes, afhangende van die stelsel se metode van werking. Tipe I-onstabiliteit en stoom-ossillasies van ’n lae intensiteit is teen lae krag en oop stelselwerkingsmodus waargeneem (stelsel oop aan die atmosfeer). Tipe II-onstabiliteit en flitsingsonstabiliteit (flashing instability) is met medium- en hoë kragopwekkings vir die oop stelsel modus van werking waargeneem. Die vloeistofvloei het meer stabiel en minder ossillerend geraak by alle kragopwekkings in die geslote stelsel van werking (stelsel nie oop na die atmosfeer nie). ’n Subverkoelingseffek was egter teen hoër krag duidelik, waar die tweefasige vloeistof se temperature sinusvormig geossilleer het. Die massavloeitempo’s het egter met hoë amplitudes in die vorentoe rigting in sommige kanale gevloei en eenrigtingvloei in ander kanale vertoon. Oor die algemeen is vloei-ewewigstoestande vroeër verkry toe die stelsel as ’n geslote stelsel bedryf is. Vir die hittepypmodus van werking het die stelsel se oorgangsweergawe in alle kanale ’n geysering onstabiliteit getoon, gevolg deur flitsinggeïnduseerde (flashing induced) kook. Gelykfasige gedrag (vloei in kanale vertoon dieselfde gedrag) en ongelykfasige gedrag (vloei in kanale vertoon teenstrydige gedrag) tussen langsliggende kanale is met al die kragopwekkings en stelselwerkingsmodusse waargeneem. Vloei-omkering in die verhitte kanale van ’n natuurlike sirkulasiestelsel is bewys om selfs onder gelyke kragopwekkings te bestaan.
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Novychenko, S. D. "Influence of ACE inhibitors and calcium channel blockers on the blood circulation in the kidney parenchyma." Thesis, БДМУ, 2021. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/18907.
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Halo, Issufo Ferrão Mário. "The influence of ocean ridges on the circulation to the south of the Mozambique channel and Madagascar." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/6478.
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Includes abstract.Includes bibliographical references (leaves 85-92).
The Mozambique Channel and the region south of Madagascar are dominated by high variability of the oceanic flow due to the ubiquitous presence of mesoscale eddies. The bottom topography of this region has several shallow ridges. The water flowing through the Mozambique Channel propagates southwards predominantly as a train of anti-cyclonic eddies, moving towards the Agulhas Current. South of Madagascar, dipolar vortices regularly propagate in a south-westward direction. Their deep extent favours interaction with the shallow bathymetry of the Davie, Mozambique and Madagascar Ridges. The role of the Madagascar Ridge on the mesoscale circulation is investigated using altimetric observations and model simulations.
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Cudaback, Cynthia Nova. "The effect of vertical mixing on along channel transport in a layered flow /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/6821.
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Orbi, Abdellatif. "Circulation de marée dans le Golfe normand-breton." Brest, 1986. http://www.theses.fr/1986BRES2024.
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Une etude de la circulation de maree dans le golfe normand-breton est menee conjointement par un modele numerique bidimensionnel horizontal de maille fine (1 mille nautique) et par des mesures, des courants lagrangiens et euleriens, de longues durees. La confrontation de ces deux methodes d'approche de la circulation a permis de valider les resultats du modele numerique. Ensuite ce dernier a ete utilise pour reproduire la circulation residuelle (circulation a long terme) dans tout le domaine d'etude. Les mecanismes de production de vorticite residuelle ont ete egalement apprehendes
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Wang, Liping. "The dynamic role of ridges in a β-plane channel : towards understanding the dynamics of large scale circulation in the Southern Ocean." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/57741.
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Wang, Fei. "Gas-Solid Fluidization: ECVT Imaging and Mini-/Micro-Channel Flow." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1290390285.
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Louchart, Arnaud. "Dynamique spatio-temporelle des communautés phytoplanctoniques côtières et de leurs caractéristiques intrinsèques, à partir d'une approche automatisée à haute résolution Phytoplankton distribution from Western to Central English Channel, revealed by automated flow cytometry during the summer-fall transition Spatial niches of phytoplankton functional groups assessed during a spring bloom development in two temperate coastal seas Untangling the vertical distribution of phytoplankton groups along a salinity gradient through the Baltic Sea and the Skagerrak-Kattegat straits." Thesis, Littoral, 2020. http://www.theses.fr/2020DUNK0556.
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Au sein des écosystèmes côtiers, la composition, la distribution et la dynamique phytoplanctoniques sont influencées par les variations spatio-temporelles des structures hydrologiques et des para mètres biogéochimiques, sous les pressions naturelles et anthropiques. Les suivis de référence, de par leur faible résolution spatiale et temporelle, peuvent manquer des événements-clés comme l'initiation ou la fin des efflorescences ou nuisibles (du type Harmful Algal Blooms). Pour permettre leur détection et mieux comprendre la distribution et la dynamique de ce compartiment à la base des réseaux trophiques et acteur majeur des cycles biogéochimiques, l'utilisation d'approches automatisées à haute fréquence permet de compléter les approches taxonomiques par la caractérisation fonctionnelle de l'ensemble du spectre de taille du phytoplancton. Cette thèse est consacrée à l'étude des caractéristiques morphologiques et physiologiques des groupes fonctionnels phytoplanctoniques définis à partir de leurs propriétés optiques à l'échelle de l'individu, rencontrés dans des mers épi-et intracontinentales contrastées en utilisant la cytométrie en flux automatisée de type "pulse-shape-recording". Tout d'abord, la distribution des groupes phytoplanctoniques et de leurs traits ont été explorés en Manche occidentale et centrale lors de la transition été-automne, ce qui a permis de mettre en évidence la formation de patches d'abondance et de biomasse à proximité du front d'Ouessant et une structuration à sub-mésoéchelle. En deuxième lieu, la dynamique des groupes fonctionnels phytoplanctoniques en Manche orientale et sud Mer du Nord a été étudiée pendant la période de développement des blooms printaniers de diatomées et de Phaeocystis globosa, avec l'utilisation de la LCBD et de la SCBD permettant l'observation de ségrégation spatiale entre groupes phytoplanctoniques dont leur distribution est expliquées par les paramètres de niche (marginalité et tolérance). Enfin, l'étude des paramètres conditionnant la distribution spatiale verticale le long d'un gradient de salinité en Mer Baltique a été abordée pendant la période estivale, en relation avec les propriétés biogéochimiques des masses d'eaux, qui a permis d'identifier les caractéristiques des groupes phytoplanctoniques participant à la distribution des groupes phytoplanctoniques. Les variations des traits ressortent comme étant les meilleurs prédicteurs de la distribution horizontale et verticale vis-à-vis des paramètres de niche et des descripteurs spatiaux (dispersion, paramètres physiques et biologiques). L'approche par traits fonctionnels, dérivés des mesures optiques à haute résolution, couplée à l'analyse de niche permettent d'avancer dans la compréhension des réponses des communautés aux gradients environnementaux, elles-mêmes détectées par les mesures d'indices de diversité. Ce travail a bénéficié de l'appui des projets régionaux (CPER MARCO), nationaux (convention MTES-CNRS) et européens (JERICO-NEXT)In coastal ecosystems, phytoplankton composition, distribution and dynamics are strongly influenced by spatial and temporal variations of hydrological structures and biogeochemical parameters, consequences of natural and anthropogenic pressures. Reference monitoring, due to its low spatial and temporal resolution, may fail to detect key events as the initiation and end of phytoplankton outbursts or harmful algal blooms (HABs). By increasing the spatial and/or temporal resolution as well as completing taxonomical counting by investigating the phytoplankton whole size spectra, the use of automated sensors may allow contributing to a better understanding of the distribution and dynamics of this major player in biogeochemichal cycles, at the basis of most foof webs. This thesis consists in studying the characteristics of phytoplankton functional groups defined from their optical properties at the single-cell level, in relation to spatio-temporal variability encountered in contrasting marginal seas, applying the pulse shape-recording automated flow cytometry. This functional classification reflects the diversity of particles according to morphological and physiological properties. First of all, the distribution of phytoplankton groups and their traits where explored in the Western and Central English Channel during the summer period. Most groups formed patches of abundance and biomass near the Ushant front and were structured at the sub-mesoscale. Secondly, phytoplankton functional groups dynamics was characterized in the Eastern English Channel and Southern North Sea during the development period of diatoms and Phaeocystis globosa spring groups, by calculating LCBD and SCBD, wich allowed the observation of spatial segregation between phytoplankton groups. Their distribution was explained by the niche parameters (marginality and tolerance). Finally, the vertical distribution of phytoplankton functional groups in a salinity gradient was addressed in the Baltic Sea, in relation to the biogeochemical properties of the water masses and the characteristics of each PFGs. The variations of the traits are thus stand out as the best predictors of the horizontal and vertical distribution of phytoplankton groups with the respect to niche parameters and spatial descriptors (dispersion, physical and biological parameters). The functional approach, derived from phytoplankton optical properties addressed by automated flow cytometry, coupled to the niche analysis, make it possible to better explain and predict community responses to environmental gradients, such responses being detected in parallel by diversity indices. This work benefited from the support of local (MARCO State-Region Plan Contract), national (CNRS-MTES convention) and international European H2020 JERICO-NEXT projects
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Watanabe, Reina. "Contribution of K+ Channels to Coronary Dysfunction in Metabolic Syndrome." Thesis, 2009. http://hdl.handle.net/1805/1908.
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Indiana University-Purdue University Indianapolis (IUPUI)Coronary microvascular function is markedly impaired by the onset of the metabolic syndrome and may be an important contributor to the increased cardiovascular events associated with this mutlifactorial disorder. Despite increasing appreciation for the role of coronary K+ channels in regulation of coronary microvascular function, the contribution of K+ channels to the deleterious influence of metabolic syndrome has not been determined. Accordingly, the overall goal of this investigation was to delineate the mechanistic contribution of K+ channels to coronary microvascular dysfunction in metabolic syndrome. Experiments were performed on Ossabaw miniature swine fed a normal maintenance diet or an excess calorie atherogenic diet that induces the classical clinical features of metabolic syndrome including obesity, insulin resistance, impaired glucose tolerance, dyslipidemia, hyperleptinemia, and atherosclerosis. Experiments involved in vivo studies of coronary blood flow in open-chest anesthetized swine as well as conscious, chronically instrumented swine and in vitro studies in isolated coronary arteries, arterioles, and vascular smooth muscle cells. We found that coronary microvascular dysfunction in the metabolic syndrome significantly impairs coronary vasodilation in response to metabolic as well as ischemic stimuli. This impairment was directly related to decreased membrane trafficking and functional expression of BKCa channels in vascular smooth muscle cells that was accompanied by augmented L-type Ca2+ channel activity and increased intracellular Ca2+ concentration. In addition, we discovered that impairment of coronary vasodilation in the metabolic syndrome is mediated by reductions in the functional contribution of voltage-dependent K+ channels to the dilator response. Taken together, findings from this investigation demonstrate that the metabolic syndrome markedly attenuates coronary microvascular function via the diminished contribution of K+ channels to the overall control of coronary blood flow. Our data implicate impaired functional expression of coronary K+ channels as a critical mechanism underlying the increased incidence of cardiac arrhythmias, infarction and sudden cardiac death in obese patients with the metabolic syndrome.
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Permata, Della. "Water circulation pattern in the main channels of Ria Formosa based on tidal analysis." Master's thesis, 2013. http://hdl.handle.net/10400.1/3559.
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Dissertação de mest., Eco-Hidrologia, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2012Ria Formosa lagoon, Southern coast of Portugal is considered as a very dynamic system. Current and water level data measurements of tidal dynamic in the main channels of Ria Formosa lagoon had been carried to figure out the hydrodynamic water circulation patterns. The aims of this study in general is to generate a recent hydrodynamic water circulation patterns based on tidal analysis, with the output of tidal dynamic characteristic (tidal propagation, tidal asymmetry and tidal distortion, energy flux and dissipation, water level and velocity longitudinal gradients, phase lag, tidal prisms, water discharge, etc) and residence time, which are used to identify the most suitable areas for seashell to grow. Several time series of water level and longitudinal component of velocity variations data during completed tidal cicles in the 12 station points of the main channel in Ria Formosa were analyzed using harmonic analysis methods and obtained the average errors of 7.5 % velocity root mean square and 6.75% elevation root mean square, respectively. The tidal analysis results when projected in GIS platform enabled to highlight water circulation patterns in the main channel of Ria Formosa and showed the significance role of Faro-Olhão inlet and Armona inlet in term of energy, volume, and discharge, and less significance role of Sao Luis inlet. The spatial variability of residence time in each stations was obtained and showed that in the west and middle regions of Ria Formosa, a good water exchange were indicated, while in east region, a high residence time magnitude was discovered especially in the inner part of east region with 6.7 days of residence time. This finding result was combined with the average current velocity and maximum flood current and found that Nave Pegos, Culatra, Cações, and Bela Romão stations and adjacent areas are the most suitable area for seashell to grow. The comparison study between inlet tidal cycle volume and geometric volume calculation was carried out and showed that volume difference represent in average a -38 cm of water level height difference estimation for all lagoon. The future development of this work will allow introducing a quality level of understanding of the system in Ria Formosa and can give contribution for the fisherman as a preliminary step to find the suitable place for doing seashell aquaculture/ harvesting. Hence, from the Eco-hydrological perspective, the result of this study could be used for the decision maker as a management tool that related to anthropogenic activities such as dredging activity, inlet opening, and other activities that can give impact to the biota life in Ria Formosa.
O sistema lagunar da Ria Formosa localiza-se na zona costeira Sul de Portugal. Este trabalho teve por principal objectivo estudar os principais padrões de circulação da água nos canais principais, tendo por base leituras de velocidade da corrente e da variação da superfície livre, medidos em vários locais na Ria Formosa. Pretendeu igualmente estudar a propagação e a dissipação de energia da maré, os gradientes longitudinais referentes à variação da superfície livre e à velocidade da corrente, os atrasos da maré em diferentes locais, os prismas de maré, os volumes de água em circulação nos canais principais, os tempos de residência e as potenciais áreas para um melhor crescimento de bivalves tendo por base vários parâmetros hidrodinâmicos. Para o efeito foram medidas série de dados referentes à variação da superfície livre e variação da velocidade na coluna de água, ao longo de ciclos de maré, em 12 estações distribuídas na Ria Formosa, que foram submetidas a uma análise harmónica. Para a componente vertical da maré foram obtidos erros RMS médios de 6.75% e para a componente horizontal de 6.75%. Os resultados obtidos desta análise, quando projectados num sistema SIG permitiram realçar a importância das barras de Faro-Olhão e da Armona na circulação hidrodinâmica deste sistema lagunar em termos energéticos, volume e caudais, bem como uma menor importância relativa por parte da barra de S. Luís. Quando analisados os tempos de residência nas várias estações em estudo, verificou-se que as regiões Central e Oeste da ria foram caracterizadas por uma boa troca de água, enquanto nos sectores mais interiores da região Este por tempos de residência elevados de aproximadamente 6.7 dias. Estes resultados quando conciliados com as respectivas velocidades médias e velocidades máximas de enchente, permitiram definir as estações de Nave Pegos, Culatra, Cações e Bela Romão (e zonas adjacentes) com as mais indicadas para o crescimento de bivalves. Quando comparados os volumes referentes aos prismas de maré obtidos através das séries de dados maregráficos medidos nas barras em análise, com os prismas de maré geométricos obtidos pela plataforma GIS, constatou-se haver uma diferença entre eles que se materializou numa diferença media da altura da água na laguna da ordem dos -38cm. Este trabalho para além de contribuir para melhor conhecimento do funcionamento hidrodinâmico da Ria Formosa, e dar um contributo para as associações de mariscadores locais com estes resultados preliminares sobre as melhores localizações para os viveiros de marisco neste sistema lagunar, poderá permitir introduzir em trabalhos futuros outros parâmetros que ajudarão a definir as melhores áreas para a implementação deste viveiros. Os resultados obtidos neste trabalho no âmbito da Eco-hidrologia, poderão ser usados não só como uma ferramenta de decisão para as entidades locais, mas também dar informações primordiais para a gestão deste sistema costeiro no que diz respeito a actividades antropogénicas, tais como a gestão de trabalhos de dragagem, a abertura de novas barras, e outras actividades que possam ter impactes no Biota da Ria Formosa.
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Berwick, Zachary C. "Role of Voltage-Dependent K+ and Ca2+ Channels in Coronary Electromechanical Coupling: Effects of Metabolic Syndrome." Thesis, 2012. http://hdl.handle.net/1805/3017.
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Indiana University-Purdue University Indianapolis (IUPUI)Regulation of coronary blood flow is a highly dynamic process that maintains the delicate balance between oxygen delivery and metabolism in order to preserve cardiac function. Evidence to date support the finding that Kv and Cav1.2 channels are critical end-effectors in modulating vasomotor tone and blood flow. Yet the role for these channels in the coronary circulation in addition to their interdependent relationship remains largely unknown. Importantly, there is a growing body of evidence that suggests obesity and its pathologic components, i.e. metabolic syndrome (MetS), may alter coronary ion channel function. Accordingly, the overall goal of this investigation was to examine the contribution coronary Kv and Cav1.2 channels to the control of coronary blood flow in response to various physiologic conditions. Findings from this study also evaluated the potential for interaction between these channels, i.e. electromechanical coupling, and the impact obesity/MetS has on this mechanism. Using a highly integrative experimental approach, results from this investigation indicate Kv and Cav1.2 channels significantly contribute to the control of coronary blood flow in response to alterations in coronary perfusion pressure, cardiac ischemia, and during increases in myocardial metabolism. In addition, we have identified that impaired functional expression and electromechanical coupling of Kv and Cav1.2 channels represents a critical mechanism underlying coronary dysfunction in the metabolic syndrome. Thus, findings from this investigation provide novel mechanistic insight into the patho-physiologic regulation of Kv and Cav1.2 channels and significantly improve our understanding of obesity-related cardiovascular disease.
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Pothina, Dharhas. "A multimodel approach to modeling bay circulation in shallow bay-ship channel systems." 2009. http://hdl.handle.net/2152/17394.
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Numerical modeling of shallow microtidal semi-enclosed estuaries requires the effective simulation of physical processes with a wide range of temporal and spatial scales. In theory, application of sufficient grid resolution in both the horizontal and vertical should result in a reasonable simulation. However, in practice, this is not the case. Fully resolving the finest scales can be computationally prohibitive, and various algorithmic assumptions can break down at fine resolutions, leading to spurious oscillations in the solution. One method of simulating inherently cross-scale phenomena is to use multimodel approaches in which domain decomposition is used to divide the region into multiple subregions, each modeled by different submodels. These submodels are coupled to simulate the entire system efficiently. In general, the different models may involve different physics, they may be dimensionally heterogeneous or they may be both physically and dimensionally heterogeneous. A reduction in computational expense is obtained by using simpler physics and/or a reduced dimension model in the submodels. In this research, we look at the particular case of modeling shallow bays containing narrow, deep ship channels. In order to accurately model bay circulation, a model should capture the effect of these spatially localized navigational channels. Our research shows that modeling techniques currently used to simulate such systems using 2 dimensional or coarse resolution 3 dimensional estuary models misrepresent wind driven surface circulation in the shallow bay and tide driven volume fluxes through the channel. Fully resolving the geometry of the ship channel is impractical on all but large parallel computing clusters. We propose a more efficient method using the multimodel approach. This approach splits the estuary into a shallow bay region and a subsurface ship channel region. By separating the physical domain into two parts in this way, simpler models can be used that are targeted at the different physical processes and geometries dominant in each region. By using a low resolution 3D model (SELFE) in the shallow bay region, coupled through appropriate interface conditions with a 2D laterally averaged model, the effects of the ship channel on bay circulation are accurately represented at a fraction of the computational expense. In this research, this coupled model was developed and applied to an ideal shallow bay- ship channel system. The coupled model approach is found to be an effective strategy for modeling this type of system.text
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Mavodza, Emma. "Investigating channels of cash circulation adopted by unbanked (African) migrants in Pretoria Central Business District (CBD)." Thesis, 2016. http://hdl.handle.net/10539/21896.
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Research Report submitted in partial fulfilment of the requirements of a Master of Arts Degree in Development studies by Coursework and Research Report.
Faculty of Humanities, University of Witwatersrand
2016This study explored cash circulation channels adopted by unbanked migrants in Pretoria Central Business District (CBD), South Africa. To understand the complex nature of cash circulation and the subjective practices of migrants, in-depth interviews were conducted with sixteen migrants selected through snowballing sampling. Collected primary data were analysed thematically, from particular to general themes depending on the responses provided by the informants. The study adopted the Sustainable Livelihoods Framework (SLF) as an analytical tool to show how in the face of structural and institutional barriers, unbanked migrants have the capability to adopt digital solutions and socially embedded channels which are more flexible and sustainable in their livelihoods. These include informal channels such as hawala, malaichas and digital solutions like Kawena and Mukuru. By using this framework, the report reveals what unbanked migrants are doing on the ground, what shapes adopted cash circulation processes and the resultant livelihood outcomes. The study aimed at contributing to previous research on money transfer mechanisms adopted by unbanked African migrants. The conclusion reached is that, by adopting various socially embedded cash circulation channels, unbanked migrants circumvent structural constraints and, by so doing, financially include more people who were previously excluded. Although the study was limited to a small sample, it raises strong implications for policy makers to look at the inherent strength of migrants as development actors. Findings from this exploratory study are critical in that they open new niches for research on migrants and financial exclusion in Africa and beyond.
GR2017
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"Loss of potassium ion channels in the cerebral circulation of hypertensive rats: Membrane associated proteins and myogenic tone." UNIVERSITY OF ARKANSAS FOR MEDICAL SCIENCES, 2010. http://pqdtopen.proquest.com/#viewpdf?dispub=3371361.
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Jeng, Haw-Ran, and 鄭浩然. "Theoretical Analysis of a Natural Circulation Boiling Channel." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/55494569332525159651.
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Chen, Wei-Lin, and 陳葦霖. "Hysteresis Effect and Channel-to-Channel Interaction in a Double-Channel Two-Phase Natural Circulation Loop." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/44563856438932918604.
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Ohashi, Kyoko. "Circulation in the Santa Maria Basin and Santa Barbara Channel." 2003. http://catalog.hathitrust.org/api/volumes/oclc/57239654.html.
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Li, Chunyan. "Tidally induced residual circulation in estuaries with cross channel bathymetry." 1996. http://catalog.hathitrust.org/api/volumes/oclc/50596770.html.
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Qiu, Bo-Ying, and 邱柏穎. "Circulating system for cooling and power supply of light-emitting diodes by using microfluidic channels." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/73174704771394964315.
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碩士明志科技大學
機械工程系機械與機電工程碩士班
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Nowadays, the trend of electronic product development includes thin and low-weight, multi-function and high density of component. The electron-ic chip features the tendency of high speed, high power and high density, and the amount of heat per unit area will rise sharply. When the volume of pack-age is reduced, poor heat dissipation will be the reason for the failure of the product. We propose that the solid conductive wire can be replaced by the mi-cro-channel of ejecting electrolyte, and the electrolyte can supply energy and exchange heat in this study. First, the electrolyte is experimental sample, and the micro-channel is fabricated by the photolithography process, and then we use the model architecture to make a microfluidic electrode. The positive and negative electrodes form a loop, the high-power light-emitting diode is signal subject, and we set up a micro-channel light-emitting diode circulating system. The power meter and temperature sensor were used to measure the effective brightness and temperature variation, and the light-emitting devices of dif-ferent micro-channels with various flow velocities are compared. In temper-ature test result, the temperature of the solid conductive module was 9.3 °C higher than that of the liquid conductive module. In brightness test result, the optical power of the solid conductive module was higher than that of the liq-uid conductive module in the initial 100 minutes, the optical power of the solid conductive module was 1.3 mW lower than that of the liquid conductive module at 120 minutes, they reached the steady states at 300 minutes, and the optical power of the liquid conductive module was still higher than that of the solid conductive module. So the optical power decay of the LED with solid conductive wire due to higher temperature is sharper than that with liquid conductive wire.
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Lin, Yuh-Ger, and 林郁格. "The nonlinear dynamic analysis of a single boiling channel two-phase circulation loop under external vertical vibration condition." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/325qyq.
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Tung, Yu-Hsin, and 董宇新. "Numerical Computations On Natural Circulation In A VHTR After A LOFA Using Subdomain Models Ranging From Single Channel To 1/12 Core." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/62330192034175615041.
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博士國立清華大學
核子工程與科學研究所
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A prismatic gas-cooled very high temperature reactor (VHTR) is being developed under the next generation nuclear plant program (NGNP) for the United States Department of Energy. It is of interest to know the flow and temperature distributions in the core during normal operation and, especially for the thermal hydraulic phenomena in the reactor core during particular accident scenarios. The accident analysis is initiated from normal operating conditions. The accuracy of the simulation for the normal operating condition depends on many design considerations for the reactor core. One important design consideration for the reactor core of a prismatic VHTR is coolant bypass flow, which occurs in the interstitial regions between fuel blocks. Present study begins with the investigation of core bypass flow phenomena for normal operating conditions, and then investigates a loss of flow accident (LOFA). The LOFA occurs when the coolant circulators are lost for some reason, causing a loss of forced convection through the core. One of the mechanisms that may occur after a LOFA for the transport of heat out of the core is by the natural convection of the coolant. It is also the objective of the present work to characterize the phenomenon of natural convection after a LOFA. Computational fluid dynamics (CFD) codes, which have simulation capabilities based on the physics of fluid flow and heat transfer, are widely used in various industrial fields. This study investigates core thermal hydraulic phenomena with the assistance of commercial CFD codes. However, the accuracy of CFD computations is affected by several parameters as well as the calculation domain, which is dependent on the capacity of computer. Present study begins with the smallest model, a 2D single channel, and then expands the CFD model gradually to partially validate and investigate the thermal hydraulic phenomena for the reactor core. Therefore, confidence in the accuracy of the biggest model involving the 1/12 core section is increased by having performed several pilot investigations. Turbulence models that perform well are then used to make steady bypass flow calculations in a symmetric one-twelfth sector of a prismatic block that includes bypass flow. Increasing surface roughness increases the maximum fuel and helium temperatures as do increases in gap width. However, maximum coolant temperature variation due to increased gap width is not changed by surface roughness. Partial validations and recommendations on turbulence model selection are also conducted in LOFA transient computations. Moreover, the present study has found that it is necessary to employ representative geometries of the core to estimate the heat transfer. By taking advantage of global and local symmetries, a detailed estimate of the strength of the resulting natural circulation and the level of heat transfer is obtained in the two sub-region model for limited capacity of computer. The effects of bypass flow after the LOFA are no longer as significant as for normal operation. Many detailed and accurate results are obtained from the 1/12 core model to characterize the phenomena occurring during the natural convection after a LOFA. These situations suggest that a larger computational domain might need to be employed for a LOFA transient condition.