Dissertations / Theses: 'Active transport (AT)'

1

Hu, Wenqi. "Active transport journey planner methodology /." Connect to thesis, 2009. http://repository.unimelb.edu.au/10187/4211.

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Schaedler, Theresia Anna. "Molecular mechanism of transport by the secondary-active multidrug transporter LmrP." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609036.

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Bechinger, Clemens. "Active Brownian motion of asymmetric particles." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-179545.

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4

Sano, Masaki, Hong-ren Jiang, and Daiki Nishiguchi. "Self-organization dynamics of active colloids." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-179578.

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5

Roughen, Kevin Michael. "Active aeroelastic control of supersonic transport aircraft." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1998391981&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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6

Harrer, Christian, Igor Gazuz, Thomas Voigtmann, and Matthias Fuchs. "Driven motion of colloids in active microrheology." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-179429.

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Bechinger, Clemens. "Active Brownian motion of asymmetric particles." Diffusion fundamentals 20 (2013) 16, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13540.

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Sano, Masaki, Hong-ren Jiang, and Daiki Nishiguchi. "Self-organization dynamics of active colloids." Diffusion fundamentals 20 (2013) 17, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13541.

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9

Decker, Michael Wilhelm. "Active acceleration compensation for transport of delicate objects." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/21258.

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10

Mehrvarzi, Christopher Omid. "Active Transport in Chaotic Rayleigh-Be?nard Convection." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/51806.

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The transport of a species in complex flow fields is an important phenomenon related to many areas in science and engineering. There has been significant progress theoretically and experimentally in understanding active transport in steady, periodic flows such as a chain of vortices but many open questions remain for transport in complex and chaotic flows. This thesis investigates the active transport in a three-dimensional, time-dependent flow field characterized by a spatiotemporally chaotic state of Rayleigh-Be?nard convection. A nonlinear Fischer-Kolmogorov-Petrovskii-Piskunov reaction is selected to study the transport within these flows. A highly efficient, parallel spectral element approach is employed to solve the Boussinesq and the reaction-advection-diffusion equations in a spatially-extended cylindrical domain with experimentally relevant boundary conditions. The transport is quantified using statistics of spreading and in terms of active transport characteristics like front speed and geometry and are compared with those results for transport in steady flows found in the literature. The results of the simulations indicate an anomalous diffusion process with a power law 2 < ? < 5/2 a result that deviates from other superdiffusive processes in simpler flows, and reveals that the presence of spiral defect chaos induces strongly anomalous transport. Additionally, transport was found to most likely occur in a direction perpendicular to a convection roll in the flow field. The presence of the spiral defect chaos state of the fluid convection is found to enhance the front perimeter by t^3/2 and by a perimeter enhancement ratio r(p) = 2.3.
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11

Pratt, Ian. "Active suspension applied to railway trains." Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/27621.

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There has been an impetus in recent years to increase railway train speeds and reduce journey times. As train speeds have increased, other problems have manifested themselves, in particular the consequent deterioration in ride quality at these higher operating speeds. Improvement in suspension design is one option which can circumvent this problem. Suspension design for a modem high-speed train has hitherto been a heuristic procedure directed towards optimising the passive components of the suspension. Performance limits are now being reached with passive suspensions due to the inherent trade-offs which need to be made in the design process. Active suspension, which eases this inherent trade-off, has received a great deal of interest in both academia and industry over recent years. A number of theoretical and experimental studies have highlighted the potential benefits of active suspension technology. Theoretical studies have concentrated on using simple vehicle models and although providing the initial impetus to active suspension they have not given the industry full confidence in them. In contrast, experimental studies have highlighted a number of problems, most notably the significant effect actuators can have on the overall performance.

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12

Granick, Steve. "Surprises from single-particle imaging of passive and active diffusion." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-179310.

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Harrer, Christian, Igor Gazuz, Thomas Voigtmann, and Matthias Fuchs. "Driven motion of colloids in active microrheology." Diffusion fundamentals 20 (2013) 7, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13529.

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14

Trout, Mark N. "Sediment transport and deposition across active faulted rift margins." Thesis, University of Leeds, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247727.

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15

Andor, Daniel Ardó. "Energy transport, reflections and noise in the active cochlea." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615187.

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16

Gazuz, Igor. "Active and passive particle transport in dense colloidal suspensions." [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:352-opus-66299.

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17

Kokk, Kersti. "Regulation of active and passive molecular transport in the testis /." Online version, 2005. http://dspace.utlib.ee/dspace/bitstream/10062/1305/5/kokk.pdf.

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18

Wang, Lipeng. "THE ROLE OF ABCG2 IN DRUG ACTIVE TRANSPORT IN MILK." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/59.

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Drug active transport into milk is a major concern for breastfeeding mothers and healthcare providers. Studies from the literature indicated that breast cancer resistance protein (ABCG2) plays an important role in drug transfer into milk. There has been limited study on stereoselective interactions with ABCG2. A mechanistic analysis of flux across cell monolayer model is a critical first step toward extrapolating in vitro results for predicting in vivo disposition (including distribution into milk), drug disposition or drug-drug interactions. The objectives of this thesis were (1) to establish a “Chemical knockout model” in rat for studying drug accumulation into milk, (2) to investigate the impact of stereoselective interaction between ABCG2/Abcg2 and pantoprazole on drug transport in milk, (3) to understand in vitro monolayer flux model using experimental data and a mechanistic mathematical model. Quantitive PCR, Western blotting and immunohistochemistry results indicated that Abcg2 was up-regulated during lactation and localized on apical side of epithelial cells in mammary gland. In vitro and in vivo experiments confirmed that Abcg2 is responsible for nitrofurantoin active transport in rat milk and GF120918 was established as a chemical knockout model. Abcg2 interacts stereoselectively with pantoprazole isomers. A significant different apical flux between two pantoprazole isomers was observed in Abcg2-MDCKII cell line. The milk to serum (M/S) ratio of (-)-pantoprazole was almost 3 times as that of (+)-pantoprazole in lactating rats. Administration GF120918 decreased M/S of (-)-pantoprazole (p<0.001) but not (+)-pantoprazole (p>0.05). A stably transfected ABCG2/Abcg2 overexpressing MDCKII cell line was successfully created and used to explore the theoretical relationships in a monolayer flux model. Based on the profiles of pantoprazole isomer transport, a simple three compartment model for drug transfer into breast milk incorporating the permeability-surface area products for passive diffusion (PSD), paracellular flux (PSPC) and apically efflux ABCG2 (PSA,E) transfection was developed. The mathematical model was developed to more fully understand the interplay of paracellular, passive diffusion, active transport, and flux kinetic parameters (Km, Vmax, IC50 and Ki). This model provided useful insights into the meaning and limitation of parameters obtained from monolayer flux.

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Wang, Fucheng. "Design and synthesis of active and passive vehicle suspensions." Thesis, University of Cambridge, 2001. https://www.repository.cam.ac.uk/handle/1810/272316.

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20

Hickson, Luke R. "Design and development of an active roll control suspension." Thesis, University of Bath, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307076.

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Granick, Steve. "Surprises from single-particle imaging of passive and active diffusion." Diffusion fundamentals 20 (2013) 1, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13521.

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22

Dal, Cengio Sara. "Competition and Response: from Active Matter to Electrolytes under Confinement." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/670864.

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Most systems in Nature manifest complex transport phenomena arising from the interplay of multiple time and length scales, be them intrinsic in the system’s dynamics or externally enforced. It is the case, for instance, of a colony of migrating cells whose competing mechanisms of self-propulsion and interaction allow for the reorganization into different tissues. Or, by ‘zooming in’ and looking at the same system on a different scale, it is the case of the ionic channels located in the membranes of the aforesaid cells. These channels typically exhibit extraordinary ion selectivity and water permeability due to the interplay between geometric confinement, surface properties and external drivings. Whether to investigate the collective structures of the former system, or the nanofluidic properties of the latter one rests on the interests of the reader. In any case, she will find some food for thought in this thesis. Here we aim at the study of the transport properties of two very different classes of systems: active matter and electrolytes under confinement. In the examples above drawn from biology, cell tissues belongs to the class of active matter and protein channels are the archetype nanometric ionic systems. We tackle the problem from a purely statistical physics viewpoint by constructing minimal models to study the system’s response to outside influences and, by doing so, learn something about its internal properties. In the case of active matter, the challenge resides in the intrinsically out-of-equilibrium nature of its constituents, having the ability to self-propel by consuming fuel stored in the environment. In Part I of the manuscript, we study how the interplay between self-propulsion and steric interactions affects the linear response of active systems. First, we construct a very general theoretical framework which allows to derive general constraints that arbitrarily out-of-equilibrium systems must fulfilled. Then, we apply it to two different minimal models of active systems to derive generalized fluctuation-dissipation relations and Green-Kubo expressions. In Part II of the manuscript we investigate the surface-dominated transport of electrolytes in (i) a nanofluidic diode and (ii) a scanning ionic conductance microscopy configuration. In both cases, we develop a theory of ionic conductivity that rationalizes previous experimental results. By doing so, we shed light on the importance of the surface versus bulk competition in controlling ionic transport and we propose a new approach to exploit it for the imaging of surface charge with nanometric resolution.
La mayoría de los sistemas en la Naturaleza manifiestan fenómenos de transporte complejos que surgen de la interacción de múltiples escalas de tiempo y longitud, ya sean intrínsecas en la dinámica del sistema o forzadas externamente. Es el caso, por ejemplo, de una colonia de células migratorias cuyos mecanismos competitivos de autopropulsión e interacción permiten la reorganización en diferentes tejidos; o, al "acercar" y mirar el mismo sistema en una escala diferente, es el caso de los canales iónicos ubicados en las membranas de las células mencionadas. Estos canales exhiben típicamente una selectividad de iones extraordinaria y permeabilidad al agua debido a la interacción entre el confinamiento geométrico, las propiedades de la superficie y los conductos externos. Ya sea para investigar las estructuras colectivas del primer sistema, o las propiedades nanofluídicas del último, se basa en los intereses del lector. En cualquier caso, encontrará algo de reflexión en esta tesis.

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23

Pilbeam, Ciaron. "Slow-active and passive control of automative suspension system vibrations." Thesis, Cranfield University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282407.

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Onishi, Viviane Leão da Silva. "Percepção dos gestores escolares sobre a utilização da caminhada para acesso à escola." Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/7781.

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Brazil's cities in recent decades have a predominance of car use as children's mode of transport to school. In carrying out the route home-school by motorized modes children practice less physical activity to the detriment of health. Policies developed in schools can play an important role in determining how students travel to school. In this context, this research aims to identify the factors that influence the perception of managers about using the walk to access the school. The focuses of the research are the municipal and private elementary schools 1. The case study was conducted in the city of São José do Rio Preto. Data collection was carried out with the school managers (directors, coordinators and teachers) through questionnaires on travel behavior of the students, information on any activities at school to teach students to behave in traffic, opinions of management on the relationship between physical activity and health of children, children's ability to to walk to school, the barriers surrounding the school and attitude of managers regarding the use of different modes of transport and the impact of vehicle traffic in urban . The results showed that the estimation of directors and coordinators on the modes of transport used by students does not differ from a survey conducted by teachers significantly, and in private schools motorized individual transport is the most used by students and public schools over half of students walk or use public transportation to school. It was found that the traffic behavior on teaching is applied in all schools, although the directors and coordinators are more likely to say that the activities are carried out in your school. The school managers have a positive perception of the importance of physical activity, with acceptance rates above 90%. There is no consensus about the best age and abilities of children to make safe decisions alone and analysis on the perception of managers of barriers around the schools that may hinder access to foot it was found that about half of the managers have positive about the quality of the environment around the schools, but other managers have indifferent opinion about the quality of the environment. Regarding the use of different modes of transport it was observed that attitudes regarding the use of buses are in general negative, more than half of managers are indifferent to automobile use and favorable to the use of the walk. In the manager's attitude regarding the impact of vehicle traffic in urban areas the vast majority of managers are concerned about the impact of traffic on the environment. Perceptions regarding the active mobility should be worked through school policies to improve students' skills as pedestrians and through public policies to improve the environment in the school environment and encourage the use of active modes of transportation.
As cidades brasileiras nas ultimas décadas vem apresentando um predomínio do uso do automóvel como modo de transporte das crianças para a escola. Ao realizarem o percurso casa-escola por modos motorizados as crianças praticam menos atividades físicas com prejuízo para a saúde. Políticas desenvolvidas nas escolas podem desempenhar um papel importante na determinação do modo como os estudantes viajam para a escola. Neste contexto, esta pesquisa visa identificar quais os fatores que influenciam na percepção dos gestores sobre a utilização da caminhada para acesso a escola. O foco da pesquisa são as escolas municipais e particulares de ensino fundamental 1. O estudo de caso foi realizado na cidade de São José do Rio Preto. A coleta de dados foi realizada junto aos gestores escolares (diretores, coordenadores e professores) através de questionários sobre comportamento de viagem dos alunos da escola, informações sobre eventuais atividades desenvolvidas na escola para ensinar aos alunos com se comportar no trânsito, opiniões dos gestores sobre o relacionamento entre atividades físicas e saúde das crianças, a habilidade das crianças para caminharem até a escola, as barreiras existentes no entorno da escola e atitude dos gestores com relação à utilização dos diferentes modos de transporte e ao impacto do tráfego de veículos no meio urbano. Os resultados mostraram que a estimativa dos diretores e coordenadores sobre os modos de transporte utilizados pelos alunos não difere significativamente do levantamento realizado pelos professores, sendo que nas escolas privadas o transporte individual motorizado é o mais utilizado pelos alunos e nas escolas públicas mais da metade dos alunos caminham ou utilizam o transporte coletivo para a escola. Verificou-se que o ensino sobre comportamento no trânsito é aplicado em todas as escolas, embora os diretores e coordenadores sejam mais propensos a afirmar que as atividades são realizadas em sua escola. Os gestores escolares têm percepção positiva sobre a importância da atividade física, com taxas de aceitação acima de 90%. Não há um consenso sobre a melhor idade e as habilidades das crianças para tomar decisões seguras sozinhas e nas análises sobre a percepção dos gestores das barreiras existentes no entorno das escolas que podem dificultar o acesso a pé constatou-se que cerca da metade dos gestores tem opinião positiva sobre a qualidade do ambiente no entorno das escolas, porém os demais gestores possuem opinião indiferente quanto a qualidade do ambiente. Com relação à utilização dos diferentes modos de transporte observou-se que as atitudes com relação ao uso do ônibus são em geral negativas, mais da metade dos gestores são indiferentes ao uso do automóvel e são favoráveis às caminhada. Na atitude do gestor com relação ao impacto do tráfego de veículos no meio urbano a grande maioria dos gestores é preocupada com o impacto do tráfego no meio ambiente. As percepções com relação à mobilidade ativa devem ser trabalhadas através de políticas escolares para melhorar as habilidades dos alunos quanto pedestres e através de políticas públicas para melhorar o ambiente no entorno escolar e incentivar o uso dos modos ativos de transporte.

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25

MIYAKE, KOJI, YOSHIKAZU TSUJI, and MASANORI YAMAMOTO. "Evidence for Active Transport of 3H-Androgens Across the Epididymal Epithelium in the Rat." Nagoya University School of Medicine, 1993. http://hdl.handle.net/2237/15932.

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26

Zhen, Juan Reith Maarten E. A. "Interaction between the human dopamine transporter and its substrates and blockers." Normal, Ill. : Illinois State University, 2005. http://proquest.umi.com/pqdweb?index=0&did=1221741311&SrchMode=1&sid=2&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1177270570&clientId=43838.

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Thesis (Ph. D.)--Illinois State University, 2005.
Title from title page screen, viewed on April 22, 2007. Dissertation Committee: Maarten E.A. Reith (chair), Hou Tak Cheung, Stephen M. Lasley, Robert L. Preston, Brian J. Wilkinson. Includes bibliographical references and abstract. Also available in print.

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27

Stewart, Lorna. "The active transport systems of proline and potassium in Escherichia coli." Thesis, University of Aberdeen, 1987. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU006337.

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The transport systems for proline and potassium represent two of the active transport systems in Escherichia coli. They have further similarities that their transport may be utilized as a response to osmotic perturbations in the environment. The exact mechanism of transport had not been totally elucidated. The transport of proline had been assumed to operate as a proton symport and as such had been used as a model system when other transport systems were being investigated. This study has demonstrated that the major route of proline uptake through the proline permease 1 (PP1), operates as a Na+ - proline cotransport which may accept Li+ in the place of Na+. Unusually, Na+ stimulates the Vmax of transport with little or no effect on the Km. In addition to this transport system, there are two other proline uptake systems which function primarily for the transport of betaine. The transport of K + is also facilitated by more than one system. The Kdp system is a K+ transporting ATPase; the TrkF system is a low rate transport system which may represent leak through another pathway. The TrkA transport system is the major system but the mechanism is not known. Transport through the system is energised by ATP and a pmf, while exchange through the system requires only ATP. The role of ATP was investigated in this study by the use of metabolic inhibitors and vesicles. It was determined that the availability of ATP affected the steady state level of potassium in the cells rather than the rate of potassium upake. It was speculated that ATP would act as a regulator of the system which would be driven by the pmf. ATP may regulate TrkA through phosphorylation or by allosteric modification of the carrier.

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Figueroa, Morales Nuris. "Active bacterial suspensions : from microhydrodynamics to transport properties in microfluidic channels." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066693/document.

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Nous étudions la dynamique de nage de bactéries Escherichia coli dans différents environnements. Leur mouvement 3D est déterminé au moyen d'un système de suivi Lagrangien 3D automatisé pour suivre des objets fluorescents que nous avons développé. Les bactéries étudiées avec ce système présentent une dispersion du coefficient de diffusion rotationnel particulièrement large, ce qui contredit la vision communément admise de la dynamique "run-and-tumble" qui a été établie pour une bactérie qui nage. Ce résultat est interprété comme une conséquence de la distribution en loi de puissance des temps de "run" expérimentaux d'un flagelle individuel, qui jusqu'alors restait indépendant de la description cinématique. Dans des écoulements confinés, la migration vers l'amont d'E. coli sur les bords reste possible pour des taux de cisaillement bien plus grands que ceux de la surface plane. La vitesse des bactéries sur les bords n'est pas influencée par l'écoulement advectif. Le mouvement vers l'amont a lieu près des parois dans une "couche limite" dont la taille varie avec le taux de cisaillement imposé. La migration vers l'amont sous écoulement et persistance de direction se combinent lors du processus de contamination. Nous montrons que les bactéries peuvent contaminer des régions propres par nage vers l'amont dans des environnements confinés.Un modèle simple, qui prend en compte la statistique de rotation du moteur, décrit de manière satisfaisante les principales caractéristiques du processus de contamination, en faisant l'hypothèse d'une distribution en loi de puissance des temps de “run”. Le modèle échoue à reproduire la dynamique quanlitative lorsque l'on prend en compte la distribution classique de run-and-tumble. Nous en concluons que le transport macroscopique de bactéries est déterminé pour la statistique de rotation du moteur
We present a study of the swimming dynamics of Escherichia coli bacteria in different physical conditions. Their 3D motion is assessed by means of a device for automated 3D Lagrangian tracking of fluorescent objects, that we developed for that purpose. Bacteria studied in that way display consistently large dispersion of the rotational diffusion coefficient, contradicting the standard vision of run-and-tumble dynamics established for an adapted bacterium. The result is interpreted as a consequence of the power law distribution of run times experimentally found for individual flagella, that up to now remained uncoupled with the motility description.We also study the bacterial swimming in polymeric suspensions, as well as in more concentrated active suspensions.In confined flows, upstream migration of E. coli at the edges remains possible at much larger flow rates compared to the motion at the flat surfaces. The bacteria speed at the edges is not influenced by the advective flow. Upstream motion takes place close to the edges in an “edge boundary layer” whose size varies with the applied flow rate. Upstream migration under flow and direction persistence combine during contamination processes. We show that bacteria can contaminate clean regions by upstream swimming in confined environments. A simple model considering the motor rotation statistics describes well the main features of the contamination process, assuming a power law distribution of run times. The model fails to reproduce the qualitative dynamics when the classical run-and-tumble distribution is determined by the motor rotation statistics

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Hamilton, Stephen Robin. "Molecular investigation of the rat jejunal active nucleoside transport protein rCNT1." Thesis, University of Leeds, 1998. http://etheses.whiterose.ac.uk/926/.

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Active, sodium-dependent nucleoside transport systems have been kinetically described in a number of different mammalian tissues. The recent cloning of several active, mammalian nucleoside transporters belonging to a novel gene family has provided an opportunity to examine both the structure/function relationships and the tissue distributions of these proteins in detail, and thus to elucidate their physiological roles. The first of these transporters to be cloned was rCNT1, a protein from rat jejunal epithelium which exhibits pyrimidine-selective, cit-type transport activity. The present study involved a bi-directional approach to the investigation of this protein by the analysis of its distribution in rat tissues at both the cellular and subcellular levels, in addition to structural investigation of rCNT1 by protein chemistry and gene manipulation techniques. A model originally proposed for the topology of this protein, based largely upon hydropathy analysis of its sequence, suggested that the N- and C-terminal hydrophilic regions of this protein were cytoplasmic. However the present study has shown, from the effect of endoglycosidase F treatment of the protein expressed in xenopus oocytes, that the C-terminal hydrophilic domain of the protein is N-glycosylated and so must in fact be extracellular. Furthermore, mutagenesis of rCNT1 cDNA allowed for the production of an aglyco-rCNT1 mutant into which novel glycosylation sites were introduced as a means of probing topology. Evidence from this mutagenesis has indicated that the N-terminus of rCNT1 is cytoplasmic, therefore suggesting that rCNTI exists in the lipid bilayer with thirteen putative transmembrane domains and not fourteen as originally proposed. Analysis of the protein sequence using predictive algorithms suggests that the originally-predicted transmembrane helix 6 is in fact extramembranous. Analysis of the distribution of rCNT1 in rat tissues by immunoblotting has revealed that this active transporter is more widespread than originally suggested by the results of Northern blotting experiments. Moreover, it has been possible by immunocytochemical analysis not only to identify the cell types in which rCNT1 is expressed but also to show that its distribution is restricted to certain domains of the plasma membrane. rCNT1 in the jejunum and kidney has been localized at the intestinal and renal brush-borders respectively. While in the liver it is abundant in the bile canalicular membranes. This location is consistent with roles for the concentrative transporter in the absorption of nucleosides from the diet or their salvage from the extracellular breakdown of nucleotides. Unexpectedly, rCNT1 also appears to be abundant in the hippocampus, and in the actively dividing seminiferous epithelium of the testis. Furthermore, its presence has also been suggested in cardiac muscle, skeletal muscle and the spleen, although these observations await further confirmation.

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Ichas, François. "La mitochondrie, organelle excitable : participation active à la signalisation calcique intracellulaire." Bordeaux 2, 1997. http://www.theses.fr/1997BOR28475.

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Hsu, Viktoria R. T. "Ion transport through biological cell membranes : from electro-diffusion to Hodgkin-Huxley via a quasi steady-state approach /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/6755.

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Aliaskarisohi, Saeedeh [Verfasser], and Thomas Martin [Akademischer Betreuer] Fischer. "Active and Passive Transport at Interfaces / Saeedeh Aliaskarisohi. Betreuer: Thomas Martin Fischer." Bayreuth : Universitätsbibliothek Bayreuth, 2011. http://d-nb.info/1015875238/34.

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Junot, Gaspard. "Transport of active bacteria : from micro-scale processes to macroscopic hydrodynamic dispersion." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS626.

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Dans cette thèse, je m’intéresse aux propriétés de transport de la bactérie Escherichia. Coli sous écoulement dans des micro-canaux. Tout d’abord, le dispositif de tracking lagrangien 3D est présenté. Cet appareil permet de suivre des bactéries nageant dans un espace à 3 dimensions et de reconstruire leurs trajectoires. Dans une première partie, grâce à une approche aux temps longs, le processus de « run and tumble » pour des bactéries nageant dans un fluide aux repos loin des surfaces est revisité. J’étudie ensuite le comportement des bactéries aux surfaces, via leurs temps de résidences, ainsi que les échanges avec les régions loin des parois. Dans une deuxième partie, les bactéries sont mises en écoulement et leurs différents comportements sont mis en évidence. Aux surfaces, plusieurs régimes rhéotactiques sont observés, dont un nouveau régime où l’orientation de la bactérie oscille. Loin des parois, les trajectoires des bactéries sont comparées à un modèle de Bretherton-Jeffery actif et de nouvelles caractéristiques, en accord avec le modèle, sont observées. Dans un dernier chapitre, je développe une méthode capable d’extraire des paramètres de mes trajectoires expérimentales. Pour conclure, je discute des conséquences des précédents résultats dans le cadre de la dispersion hydrodynamiques
In this thesis, I investigate the transport properties of Escherichia. Coli bacteria in a flow. First I introduce the Lagrangian 3D tracker that I used and improved. This apparatus allows to follow bacteria in 3 dimensions over long periods of time and large spaces in a quiescent fluid or under flow and is the suitable tool to study microscopic properties of bacteria. Then I focus on the motility of bacteria in the bulk of quiescent fluids. Especially, I focus on the "run and tumble" process and bridge the gap between the short-time and long-time approach. I then study the long time behavior of bacteria at surfaces as well as the exchange with the bulk. The flow is then turned on and the behavior of bacteria at surfaces, submitted to different shear, is studied. To have a general picture of bacterial transport, all the effects due to surfaces, shear and bacteria activity and shape are considered. I also focus on bacterial trajectory in the bulk under flow. I find new features and compare my experimental result to an active Bretherton-Jeffery model. In a last chapter, thanks to a theoretical framework, I build a method able to extract parameters from my experimental data. To conclude, I discuss the implication of my work in the framework of bacterial transport and dispersion

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34

Fuest, Marie. "Active Electrokinetic Transport Control in a Nanofluidic Device with Embedded Surface Electrodes." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449484271.

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Sekhar, Gayathri Nair. "The transport of CNS-active cationic drugs across the blood-brain barrier." Thesis, King's College London (University of London), 2016. https://kclpure.kcl.ac.uk/portal/en/theses/the-transport-of-cnsactive-cationic-drugs-across-the-bloodbrain-barrier(41ff27df-17ce-4edc-82fe-c4169edf801c).html.

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The physical, transport, and metabolic barriers presented by the cerebral microvessel endothelium - the blood- brain barrier (BBB) - protect the brain from damage from toxic substances and ensure the delivery of nutrients required for the functioning of the brain thus creating a stable neuronal microenvironment. However, the BBB poses a challenge to many CNS-active drugs which must cross the BBB to reach their target. Of the drugs that target the brain, many are cationic at physiological pH making their transport into the brain even harder with the additional potential for drug-drug interactions. Therefore, this thesis has been an attempt to understand the transport characteristics of cationic therapeutic drugs across the BBB. One of the foci of this study has been the anti-human African trypanosomiasis (HAT) drugs pentamidine and e ornithine, both positively charged at physiological pH. Pentamidine is a stage 1 drug for HAT that was previously found in our laboratory to not cross the mouse BBB in vivo as it was a substrate for eux transporters, particularly P-glycoprotein. The present study observed that pentamidine is taken up by Organic Cation Transporter 1 (OCT1) in hCMEC/D3 (human) and bEnd.3 (mouse) cell lines where it accumulates and is euxed by ATP-dependent mechanisms out of the cell. In addition, the predominant localisation of OCT1 at the luminal membrane of the BBB may explain the low permeability of pentamidine into the brain. Considering pentamidine is a substrate for P-glycoprotein at the BBB, inhibitors of Pglycoprotein were used to increase pentamidine delivery into the brain. Pluronic® triblock polymers P85, P105, and F68 were thus chosen for their proven ability to inhibit P-glycoprotein and for their promising results from clinical trials. They were used at concentrations of 0.01%, 0.025%, 0.1%, and 0.5% along with pentamidine in an attempt to increase its delivery across the BBB, concomitantly reducing any side-e ects. In vitro assays carried out on MDCK-hMDR cell line suggested high concentrations of P85 and P105 were cytotoxic even though P85 was able to signi cantly increase pentamidine permeability at 0.5% and 0.1%. Greater speci city to a target could circumvent toxicity issues in the future. The second anti-HAT drug studied was e ornithine that treats stage 2 of HAT. To treat stage 2 of the disease it must cross the BBB, yet it was not found to cross the BBB in the in vivo study on mice carried out in our laboratory. Results obtained from assessing the accumulation of e ornithine in hCMEC/D3 and bEnd.3 cell lines, the in vitro models of the BBB, also suggested limited entry of e ornithine into the BBB. Nonetheless, the assays indicated that e ornithine could be a weak substrate for system y+ at the BBB. There was also evidence for its interaction with OCTs in the bEnd.3 cell line. Second part of the thesis focussed on the antipsychotic drugs haloperidol and amisulpride, both cationic drugs at physiological pH. Haloperidol, an extensively used drug both as an antipsychotic and for palliative care, has the potential to interact with other drugs at the BBB. Haloperidol was found to be a substrate for OCTs at the BBB in both hCMEC/D3 and bEnd.3 cell lines and was found to accumulate readily inside the BBB cells. Similarly, amisulpride is an antipsychotic that is also used to treat delusions and aggression in Alzheimer's disease (AD). Previous studies found increased central dopamine receptor occupancy in AD patients when amisulpride was administered at very low doses. Unlike haloperidol, amisulpride had very low accumulation inside the BBB cells. Results suggested amisulpride to be a substrate for the OCTs and the eux transporters MATE1 and PMAT at the BBB. Amisulpride entry into the brain was also tested in wildtype and transgenic AD mice to nd that amisulpride entry into the transgenic mice brains was signi cantly greater than wildtype mice brains and this was not due to a `leaky' BBB of the AD model. Changes to the expression levels of OCT1, 2, 3 and P-glycoprotein transporters in wildtype and AD model mice BBB were determined using Western blotting and no di erences were found. Further exploration of capillaries isolated from human brain samples from control and AD a ected patients was carried out and signi cant region-speci c changes to the expression levels of MATE1 was observed. There was also a tendency for region-speci c decrease in PMAT expression levels. MATE1 and PMAT are proton-dependent transporters that eux substrates out of the BBB. This decrease in eux transporter expression at the BBB of AD patients could explain the increased sensitivity in AD patients to amisulpride.

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36

Martin, Charlotte Anne. "Sorption and transport of selected nonionic surfactants in soil systems." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/19118.

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Hill, David Brooks. "Changes in the number of molecular motors driving vesicle transport in PC12 /." Electronic thesis, 2003. http://dspace.zsr.wfu.edu/jspui/handle/10339/206.

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38

Jones, Kevin. "Intracellular accumulation of the HIV protease inhibitors and the effect of active transport." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366660.

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Reichert, Julian [Verfasser], and Hartmut [Gutachter] Löwen. "Transport Coefficients in Dense Active Brownian Particle Systems / Julian Reichert ; Gutachter: Hartmut Löwen." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2021. http://d-nb.info/1227038607/34.

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40

Doory, Layla Kim. "Development of catalytic reactor designs for enhanced CO oxidation." Thesis, University College London (University of London), 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282799.

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41

Thomson, Robert Brent. "Cellular mechanisms of acid/base transport in an insect excretory epithelium." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/31306.

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The cellular mechanisms responsible for rectal acidification in the desert locust, Schistocerca gregaria, were investigated in isolated recta mounted as flat sheets in modified Ussing chambers. In the absence of exogenous CO₂, HCO₃⁻, and phosphate, the isolated rectum (under both open- and short-circuit current conditions) was capable of rates of net acid secretion (J[subscript]H+) similar to those observed in vivo, demonstrating the viability of the preparation and suggesting that rectal acidification was due to proton secretion rather than selective movements of HCO₃⁻ or phosphate. The possibility that trace levels of metabolic CO₂ might be generating sufficient HCO₃⁻ to account for the observed rates of rectal acidification (via HCO₃⁻ reabsorption) was assessed by adding exogenous CO₂/HCO₃⁻ to the contraluminal bath. The small increases in J[subscript]H+ observed after addition of 2% or 5% CO₂ were shown to be due to simple hydration of CO₂ which had diffused into the lumen (from the contraluminal bath), rather than changes in rates of HCO₃⁻ reabsorption. Since measurable quantities of luminal HCO₃⁻ did not directly affect the apical acid/base transport mechanism per se, it was concluded that metabolic CO₂ could not generate sufficient HCO₃⁻ in the lumen to account for the rates of rectal acidification observed under nominally CO₂/HCO₃⁻-free conditions and that J[subscript]H+ must be due to a proton secretory rather than bicarbonate reabsorptive mechanism. Microelectrode measurements of intracellular pH (pHi) and apical and basolateral membrane potentials (Va and Vb respectively) indicated that luminal pH was not in equilibrium with either contraluminal pH or pHi and that the mechanism responsible for active luminal acid secretion resided on the apical membrane. Preliminary measurements of bath total ammonia (ie. NH₃ + NH₄+) levels in the previous experiments suggested that the rectum was actively secreting ammonia at significant rates across the apical membrane into the lumen. If the ammonia crossed the apical membrane as NH₃ rather than NH₄+, rates of luminal ammonia secretion (J[subscript]Amm) would have to be added to J[subscript]H+ to obtain corrected values of luminal proton secretion. In the absence of exogenously added ammonia and CO₂, ammonia was preferentially secreted into the lumen under both open- and short-circuit current conditions. J[subscript]Amm was dependent on the presence of luminal amino acids and was relatively unaffected by K[superscript]+ removal or changes in luminal pH from 7.00 to 5.00. Bilateral Na+ substitution or luminal addition of ImM amiloride reduced J[subscript]Amm by 63% and 65% respectively. The data consistently demonstrate that the rectum secretes significant quantities of endogenously produced ammonia preferentially into the lumen as NH₄+ rather than NH₃ via an apical Na[superscript]+/NH₄[superscript]+ exchange mechanism. Clearly, rates of net acid secretion estimated by titratable acidity do not have to include a correction for luminal ammonia secretion. Although J[subscript]H+ was completely unaffected by changes in contraluminal pH, it could be progressively reduced (and eventually abolished) by imposition of either transepithelial pH gradients (lumen acid) or transepithelial electrical gradients (lumen positive). Under short-circuit current conditions, the bulk of J[subscript]H+ was not dependent on Na[superscript]+, K[superscript]+, CI⁻, Mg₂+, or Ca+ and was due to a primary electrogenic proton translocating mechanism located on the apical membrane. A small component (10-16%) of J[subscript]H+ measured under these conditions could be attributed to an apical amiloride-inhibitable Na[superscript]+/H[superscript]+ exchange mechanism. Inhibition of JH+ by anoxia or reduction of luminal pH unmasked a significant proton diffusional pathway on the apical membrane in parallel with the active proton pump. The fact that J[subscript]H+ was significantly inhibited (42%-66%) by contraluminal addition of ImM cAMP and relatively unaffected by changes in contraluminal pCO₂ or pH suggests that net acid secretion in the locust rectum in vivo is modulated by circulating hormonal factors rather than haemolymph pH or pCO₂ per se.
Science, Faculty of
Zoology, Department of
Graduate

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42

Lopez, Hector Matias. "Influence of the coupling between flow and bacteria on the fluid rheology and on bacterial transport." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112168.

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Le transport des micro-organismes, comme par exemple les bactéries, par un fluide se retrouve au centre de thématiques de recherche dans des domaines aussi variés que de la biologie, l’écologie, l’ingénierie et la médecine.Ce manuscrit résume mon étude expérimentale du couplage entre le mouvement microscopique de la nage des bactéries et le mouvement advectif de l’écoulement.La première partie du manuscrit porte sur la rhéologie des suspensions d’E. coli sous faible taux de cisaillement. Pour cette condition, j’ai montré que les perturbations hydrodynamiques induites par la nage réduisent fortement la viscosité. Cet effet peut-être si important pour qu’il soit suffisant pour compenser entièrement la perte visqueuse due au cisaillement.La seconde partie traite des expériences d’écoulement réalisées dans un canal capillaire. Pour cette géométrie, j’ai examiné le couplage pour des écoulements caractérisés par un plus fort taux de cisaillement. Le suivi des trajectoires et le dénombrement des bactéries m’ont permis de mettre en évidence l’existence d’une composante de vitesse normal à la direction de l’écoulement. Cette dernière montre que les bactéries suivent des trajectoires hélicoïdales qui s’enroulent autour du centre du capillaire d’une façon antihoraires. Cette nouvelle composante est corrélée à la migration préférentielle des bactéries dans une couche de localisation proche de la paroi du canal.Les couplages rhéotactiques bactéries/fluide que j’ai étudiés doivent avoir des conséquences potentielles sur le transport en géométries plus complexes qui mériteraient une étude particulière
The question of transfer and spreading of living microorganisms, such as motile bacteria, is of interest in biology and ecology, but also in engineering and medicine.The way in which the background flow affects the behavior of these bacteria and how it impacts the bacterial transport through complex systems and on the macroscopic properties of the fluid remains unclear and little studied.In this thesis, I present an experimental investigation of the coupling between the local bacteria-driven motion and the fluid advection.In a first part, I investigate the rheological response of E. coli suspensions when subjected to weak flows (low shear rates). I show that, in particular conditions, the microscopic perturbations caused by the bacteria highly impact on the macroscopic viscosity of the suspension, leading to a striking viscosity decrease and eventually overcoming the dissipative effects due to viscous loss. I also identify the relevant time scales defining this viscosity decrease.In a second part, I perform experiments in a capillary channel and analyze the coupling for stronger flows (higher shear rates), at which bacteria were found not to impact on the macroscopic viscosity. Instead, by analyzing the bacterial trajectories under flow, I evidence a breakage of the symmetry of this trajectories which, characterized by a preferential migration, causes the localization of the bacteria in a layer that extends over a significant distance from the surface, and thus potentially influencing the bacterial transport in complex systems

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Popp, Christian. "Cuticular transport of hydrophilic molecules with special focus on primary metabolites and active ingredients." Doctoral thesis, [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=980171989.

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Grigorescu, Eduard. "Reducing internet latency for thin-stream applications over reliable transport with active queue management." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=236098.

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An increasing number of network applications use reliable transport protocols. Applications with constant data transmission recover from loss without major performance disruption, however, applications that send data sporadically, in small packets, also called thin-streams, experience frequently high latencies due to 'Bufferbloat', that reduce the application performance. Active Queue Management mechanisms were proposed to dynamically manage the queues in routers by dropping packets early and reduce these, hence reducing latency. While their deployment to the internet remains an open issue, the proper investigation into how their functioning mechanism impacts latency is the main focus of this work and research questions have been devised to investigate the AQM impact on latency. A range of AQM mechanisms has been evaluated by the research, exploring performance of the methods for latency sensitive network applications. This has explored new single queue AQM mechanisms such as Controlled Delay (CODEL) and Proportional Integral Enhanced (PIE) and Adaptive RED (ARED). The evaluation has shown great improvements in queuing latency when AQM are used over a range of network scenarios. Scheduling AQM algorithms such as FlowQueue CODEL (FQ-CODEL) isolates traffic and minimises the impact of Bufferbloat on flows. The core components of FQ-CODEL, still widely misunderstood at the time of its inception, have been explained in depth by this study and their contribution to reducing latency have been evaluated. The results show significant reductions in queuing latency for thin streams using FQ-CODEL. When TCP is used for thin streams, high application latencies can arise when there are retransmissions, for example after dropping packets by an AQM mechanism. This delay is a result of TCP's loss-based congestion control mechanism that controls sender transmission rate following packet loss. ECN, a marking sender-side improvement to TCP reduces applicationlayer latency without disrupting the overall network performance. The thesis evaluated the benefit of using ECN using a wide range of experiments. The findings show that FQ-CODEL with ECN provides a substantial reduction of application latency compared to a drop-based AQM. Moreover, this study recommends the combination of FQ-CODEL with other mechanisms, to reduce application latency. Mechanisms such as ABE, have been shown to increase aggregate throughput and reduce application latency for thin-stream applications.

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Krüger, Wolf. "Integrated design process for the development of semi-active landing gears for transport aircraft." [S.l. : s.n.], 2000. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9640837.

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Löf, Emelie. "Bil eller aktiv transport : Vad påverkar människor till deras val?" Thesis, University of Gävle, Faculty of Health and Occupational Studies, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-7062.

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Syftet med denna uppsats var att undersöka vilka faktorer som påverkar hur förvärvsarbetande människor i Gävle använder sig av bil och aktiv transport när de transporterar sig till destinationer inom staden. Tio personer, fem butiksbiträden och fem lärare, intervjuades angående deras transportvanor och resonemang kring valet av transportsätt.Resultatet visade att aktiv transport var det vanligaste transportsättet till arbete, träning och butiker i centrum medan bilen var det vanligaste transportsättet till mataffären och destinationer på längre avstånd från hemmet. Avståndet till destinationen, tiden det tar att transportera sig, transport av eventuella varor, bekvämlighet, intresse av motion och rekreation, årstid, väder samt synen på ekonomi och miljö var faktorer som påverkade om deltagarna valde att transportera sig med bil eller aktiv transport. Definitionen på de olika faktorerna varierade mellan deltagarna, vilket kan tyda på att det är den personliga uppfattningen om de olika faktorerna som avgör vilket transportsätt som väljs. Det framkom ingen märkbar skillnad i resvanor mellan deltagare med olika utbildning och arbete.

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47

Rheault, Mark Ronald O'Donnell Michael J. "Transport of organic cations and anions by the isolated Malpighian tubules of insects." *McMaster only, 2005.

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48

Karpf, Ditte Maria. "Intestinal lipoprotein secretion and lymphatic transport of poorly aqueous soluble compounds /." Kbh. : The Danish University of Pharmaeutical Sciences, Department of Pharmaceutics, 2005. http://www.dfuni.dk/index.php/Previous_PhD_Defences_2005/1735/0/.

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Martin, Aimee Selina. "An Accessible City An investigation using GIS into the potential for further development of the proposed major cycleways network for Christchurch, New Zealand." Thesis, University of Canterbury. Geography, 2015. http://hdl.handle.net/10092/10723.

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As the future of the world’s oil reserves becomes progressively more uncertain, it is becoming increasingly important that steps are taken to ensure that there are viable, attractive alternatives to travel by private motor vehicle. As with many of New Zealand’s major urban centres, Christchurch is still exceptionally reliant on private motor vehicles; although a significant proportion of the population indicate that they would like to cycle more, cycling is still an underutilised mode of transport. Following a series of fatal earthquakes that struck the city in 2010 and 2011, there has been the need to significantly redevelop much of the city’s horizontal infrastructure – subsequently providing the perfect platform for significant changes to be made to the road network. Many of the key planning frameworks governing the rebuild process have identified the need to improve Christchurch’s cycling facilities in order to boost cycling numbers and cyclist safety. The importance of considering future growth and travel patterns when planning for transport infrastructure has been highlighted extensively throughout literature. Accordingly, this study sought to identify areas where future cycle infrastructure development would be advantageous based on a number of population and employment projections, and likely future travel patterns throughout the city. Through the use of extensive GIS analysis, future population growth, employment and travel patterns for Christchurch city were examined in order to attain an understanding of where the current proposed major cycleways network could be improved, or extended. A range of data and network analysis were used to derive likely travel patterns throughout Christchurch in 2041. Trips were derived twice, once with a focus on simply finding the shortest route between each origin and destination, and then again with a focus on cyclist safety and areas where cyclists were unlikely to travel. It was found that although the proposed major cycleways network represents a significant step towards improving the cycling environment in Christchurch, there are areas of the city that will not be well serviced by the current proposed network in 2041. These include a number of key residential growth areas such as Halswell, Belfast and Prestons, along with a number of noteworthy key travel zones, particularly in areas close to the central city and key employment areas. Using network analysis, areas where improvements or extensions to the proposed network would be most beneficial were identified, and a number of potential extensions in a variety of areas throughout the city were added to the network of cycle ways. Although it has been found that filling small gaps in the network can have considerable positive outcomes, results from the prioritisation analysis suggested that initially in Christchurch demand is likely to be for more substantial extensions to the proposed major cycleways network.

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Ralfs, Carla. "Transport of metabolic active bacteria through saturated quartz sand columns with and without substrate addition." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=984411267.

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Dissertations / Theses on the topic 'Active transport (AT)'

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