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MADANIA, AMMAR. "Etude fonctionnelle des proteines apparentees a l'actine, arp2 et arp3 ; recherche de proteines interactant chez la levure saccharomyces cerevisiae." Université Louis Pasteur (Strasbourg) (1971-2008), 1998. http://www.theses.fr/1998STR13083.
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Ce travail porte sur la caracterisation de deux proteines apparentees a l'actine arp2 et arp3 (actin related protein), chez la levure s. Cerevisiae. Par l'analyse cytologique de mutants thermosensibles arp2 et arp3, nous avons montre que ces deux proteines sont essentielles pour l'organisation du cytosquelette d'actine et pour l'endocytose. Un crible double-hybride nous a permis d'identifier plusieurs partenaires d'arp2p , dont arp2p elle-meme, l'actine et le facteur d'elongation ef1, recemment identifie comme une proteine fixant l'actine. De plus, arp2p et arp3p interagissent genetiquement et dans le systeme double-hybride, confirmant l'existance de ces deux arps dans un complexe multiproteique. Nous avons montre que la surexpression de las17p est capable de supprimer d'une facon allele-specifique les defauts de croissance, d'organisation du cytosquelette d'actine et d'endocytose aussi bien de mutants arp2 que arp3 ts. De plus, arp2p, arp3p et las17p colocalisent avec les taches corticales d'actine. Las17p est homologue de la proteine wasp (wiskott-aldrich syndrome protein) impliquee dans une maladie genetique humaine d'immunodeficience. La deletion du gene las17 dans la levure entraine soit la letalite, soit la thermosensibilite, selon le contexte genetique. Les cellules las17 viables accumulent des agregats aberrants d'actine, semblables aux agregats observes dans les mutants arp2 et arp3 ts. Grace a un crible double-hybride, nous avons identifie des partenaires de las17p, dont l'actine, la verproline, et plusieurs proteines a domaine sh3, suggerant que las17p est impliquee dans des voies de signalisation et de regulation du cytosquelette d'actine. L'interaction de las17p avec lsb6p (l'homologue de cip4p humaine) suggere un lien entre las17p et cdc42p. Nos resultats convergent vers l'implication d'arp2p, arp3p et las17p dans l'organisation du cytosquelette cortical d'actine, probablement par un mecanisme de nucleation et de stabilisation des filaments d'actine.
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Ma, Huailiang, and 马怀良. "Identification of human annexin A6 as a novel cellular interactant of influenza A virus M2 protein and regulator of virus budding andrelease." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48521747.
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Influenza viruses exploit sophisticated host cell machinery to replicate, causing both seasonal epidemics and unpredictable pandemics. Studying the host cellular factors interacting with conserved domains of viral proteins will help us to identify key host proteins for the virus infection. This will not only strengthen our understanding of the precise mechanisms of the virus life cycle, but also pave new avenues for anti-viral development.
The cytoplasmic tail of M2 ion channel (M2/CT) is one of these highly conserved domains. It is fully accessible to the host cell machinery after fusion of the virus envelope with the endosomal membrane and during the trafficking, assembly, and budding processes. I hypothesized that recruitment of host cellular factors by M2/CT may regulate the M2-dependent stages of the virus life cycle. Through a large scale yeast two-hybrid (Y2H) screen with the M2/CT used as bait, the human annexin A6 was identified as a novel host cell interactant and this interaction was further confirmed by both GST pull-down assay on purified proteins and co-immunoprecipitation assay on virus infected cells.
A functional characterization of this novel interaction demonstrated that depletion of annexin A6 could enhance the virus production, while its overexpression could reduce the virus propagation, which indicates that annexin A6 is a negative regulator of the virus infection. However, I found that the virus infection could not induce any changes of annexin A6 expression. Therefore, the annexin A6-mediated regulation may depend on the subcellular localization where the interaction with M2/CT occurs. To decipher which step of the virus replication is regulated, we dissected the virus life cycle and found that modulation of annexin A6 expression had no effect on the early stages of the virus life cycle or on viral RNA replication but impaired the release of progeny virus, as suggested by delayed or defective budding events observed at the plasma membrane of virus-infected and annexin A6-overexpressing cells during a transmission electron microscopy study. To further decipher the underlying molecular mechanisms, the contribution of annexin A6-mediated plasma membrane lipid rafts reorganization through cholesterol homeostasis modulation and cortical actin cytoskeleton remodeling was also investigated.
In conclusion, here I have identified the human annexin A6 as a novel host cell interactant of M2/CT that negatively modulate the influenza virus infection by impairing the virus budding and release. This work further supports the idea that M2 is a multifunctional protein and is also consistent with the discovery by Rossman et al. that M2/CT mediates the virus budding process (Rossman et al., 2010). This study further emphasizes the importance of host cell interactants of M2/CT in this process. Regarding the biology of annexins, this study also adds a new member of this protein family in the list of regulators of influenza virus infection.<br>published_or_final_version<br>Public Health<br>Doctoral<br>Doctor of Philosophy
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Malicorne, Sébastien. "Recherche d’interactants du domaine immunosuppresseur des protéines d’enveloppe rétrovirales." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS579.
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La plupart des virus ont développé des mécanismes de résistance ou de suppression du système immunitaire pour parvenir à infecter durablement leur hôte. Ces mécanismes demeurent encore imparfaitement connus. Un domaine immunosuppresseur (IS) a été identifié au niveau de la région transmembranaire des protéines d’enveloppe des rétrovirus endogènes ou infectieux. Ce domaine hautement conservé a été décrit par exemple comme inhibant l’activation lymphocytaire. Dans le laboratoire, il a été caractérisé en particulier via des expériences de rejet de cellules tumorales in vivo, ce qui a permis de définir des mutations inactivatrices. Afin de mieux comprendre les mécanismes de résistance des rétrovirus au système immunitaire, mes travaux de thèse ont porté sur l’identification de la ou des protéines capables d’interagir avec le domaine IS. Plusieurs approches cellulaires et moléculaires ont été développées, basées pour la plupart sur l’utilisation de sondes fluorescentes obtenues par synthèse chimique, constituées des domaines IS provenant de différents rétrovirus. Dans un premier temps, les cellules du système immunitaire qui lient les protéines virales ont été identifiées : les lymphocytes B et les cellules myéloïdes (monocytes, cellules dendritiques et macrophages). Dans un second temps, des expériences de co-immunoprécipitation et de chromatographie d’affinité couplées à la spectrométrie de masse ont été réalisées dans le but d’identifier sur ces cellules les protéines membranaires responsables de ces liaisons. Plusieurs agents de couplages chimiques ont été utilisés afin de maintenir les liaisons domaine IS - protéine de faibles affinités. En raison de résultats non-reproductibles obtenus au cours de ces expériences, des tests de liaison du domaine IS sur des cellules transfectées avec des banques d’ADNc, ou lors d’expériences de double hybride ont été réalisées. Ces deux approches ont permis d’identifier des protéines membranaires potentiellement impliquées dans la liaison du domaine IS : les protéines X1 et X2. Les co-transfections de vecteurs d’expression du domaine IS et de X2 ont mis en évidence des interactions protéiques au cours d’expériences de co-immunoprécipitation et de microscopie confocale, en particulier avec le domaine IS du rétrovirus HIV-1. Concernant X1, sa transfection induit la liaison cellulaire des domaines IS de HERV-W et MLV. En revanche, aucune interaction directe entre X1 et le domaine IS n’a pu être démontrée, notamment dans des expériences de co-immunoprécipitation et de microscopie confocale.La découverte des protéines membranaires qui interagissent avec le domaine IS demeure un enjeu critique pour la compréhension des voies de signalisation et de transcription qui permettent aux rétrovirus d’exercer leur effet sur le système immunitaire, l’objectif de ces travaux étant d’identifier à terme des nouvelles cibles thérapeutiques.En conclusion, même si des travaux complémentaires demeurent nécessaires, les protéines X1 et X2 pourraient contribuer à l’immunosuppression rétrovirale<br>Most viruses have developed mechanisms of resistance or suppression of the immune system to achieve lasting infection of their host. These mechanisms are still imperfectly known. An immunosuppressive (IS) domain has been identified in the transmembrane region of envelope proteins of endogenous or infectious retroviruses. This highly conserved domain has been described, for example, as inhibiting lymphocyte activation. In the laboratory, it has been characterized by tumor cell rejection experiments in vivo, which has made it possible to define inactivating mutations. In order to better understand the mechanisms of resistance of retroviruses to the immune system, my thesis focused on the identification of the protein(s) interacting with the IS domain. Several cellular and molecular approaches have been developed, based for the most part on the use of fluorescent probes obtained by chemical synthesis, consisting of IS domains from different retroviruses. At first, immune system cells that bind viral proteins have been identified: B cells and myeloid cells (monocytes, dendritic cells and macrophages). In a second step, co-immunoprecipitation and affinity chromatography coupled to mass spectrometry were performed to identify on these cells the membrane proteins responsible for these bonds. Several chemical coupling agents have been used to prevent detachment of low affinity binding between proteins and the IS domain. Due to non-reproducible results obtained during these experiments, IS domain binding assays on cells transfected with cDNA libraries, or in double hybrid experiments were performed. These two approaches made it possible to identify membrane proteins potentially involved in the binding of the IS domain: the X1 and X2 proteins. Co-transfections of IS domain and X2 expression vectors demonstrated protein interactions in co-immunoprecipitation and confocal microscopy experiments, particularly with the IS domain of the HIV-1 retrovirus. Concerning X1, its transfection induces binding of the IS domains of HERV-W and MLV on cells membrane. On the other hand, no direct interaction between X1 and the IS domain could be demonstrated, especially in co-immunoprecipitation and confocal microscopy experiments.The discovery of membrane proteins that interact with the IS domain remains a critical issue for understanding the signaling and transcription pathways that allow retroviruses to exert their effect on the immune system, the aim of this work being to identify new therapeutic targets.In conclusion, although further work is still needed, the X1 and X2 proteins may contribute to retroviral immunosuppression
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Hart, Alison Claire. "Interacting thermals." Thesis, University of Cambridge, 2008. https://www.repository.cam.ac.uk/handle/1810/252113.
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This thesis addresses the question of how thermals evolve and interact when released in proximity to one another. The research reported focuses on the simultaneous release of an isolated group of thermals in a larger domain, rather than an array of thermals spanning a whole horizontal plane. With multiple thermals, the fluid available between the thermals is limited and this might be expected to lead to competition between the thermals for the surrounding fluid. The evolution of the thermals and the interaction between them will depend on their initial separation. If released close enough to each other there will be mixing between them and, in some cases, merging, whereas if the separation is large compared with the depth of the domain they may be expected to develop as if in isolation. Initially, the results for a thermal released in isolation are studied and the sensitivity to changes in initial buoyancy and the arrangement of fluid are examined. Having determined the experimental constants for an isolated thermal with certain initial conditions, the change in behaviour from the isolated self-similar case due to the presence of a second thermal is considered. A surprising lack of interaction between the thermals before the point at which the thermals first come into contact is discovered and a possible model for two thermals released in proximity to each other is suggested. In order to better understand the merging of the thermals the flow is considered from different angles of view. The distribution of mass within each two-dimensional projection is examined and compared to that of an idealised spherical thermal with uniform density as well as other possible models for a thermal.
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Mikitova, Veronika. "CDKA interacting proteins." Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502199.
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Progression through the cell cycle relies on activity of cyclin-dependent kinases (CDKs) and their regulatory subunits, cyclins. CDKA and CDKB are the main components of the G2/M transition point in Arabidopsis thaliana. I aim to gain a better understanding of how mitotic kinases, CDKA and CDKB. mediate control of translation initiation and other biological processes throughout the cell cycle. To address this question, I used different approaches to identify interacting partners of CDKA and CDKB (and other cell cycle regulators). CDKA directly interacts with the complex that binds the 5' mRNA cap. In proliferating cells, CDKA associates with translation initiation factor eIF4A as demonstrated by reciprocal immonoprecipitation (Hutchins et al., 2004). To understand this interaction in greater depth, I used a pair-wise yeast two hybrid to test interactions between cell cycle regulators and translation initiation factors. I confirmed the association of translation initiation factors that is in agreement with the mechanism of cap complex assembly in animals and yeast and identified eIF4A and eIF4E as a putative substrates of both CDKA and CDKB2;1.
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Graham, B. T. "Interacting stochastic systems." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599589.
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The Ising model was suggested by Lenz in 1920. It is a probabilistic model for ferromagnetism. Magnetization can then be explored as correlation between spin random variables on a graph. Bond percolation was introduced by Simon Broadbent and John Hammersley in 1957. It is a model for long range order. Edges of a lattice graph are declared open, independently, with some probability <i>p</i>, and clusters of open edges are studied. Both these models can be understood as aspects of the random-cluster model. In this thesis we study various aspects of mathematical statistical mechanics. In Chapter 2 we create a diluted version of the random-cluster model. This allows the coupling of the Ising model to the random-cluster model to be extended to include the Blume-Capel model. Crucially, it retains some of the key properties of its parent model. This enables much of the random-cluster technology to be carried forward. The key issue for bond percolation concerns the fraction of open edges required in order to have long range connectivity. Harry Kesten proved that this fraction is precisely one half for the square planar lattice. Recent development in the theory of influence and sharp thresholds allowed Béla Bollobás and Oliver Riordan to simplify parts of his proof. In Chapter 3 we extend an influence result to apply to monotonic measures. This allows sharp thresholds to be shown for certain families of stochastically increasing monotonic distributions, including random-cluster measures. In Chapter 4 we study time to convergence for a mean-field zero-range process. The problem was motivated by the canonical ensemble model of energy levels used in the derivation of Maxwell-Boltzmann distributions. By considering the entropy of the system, we show that the empirical distribution rapidly converges – in the sense of Kullback-Leibler divergence – to a geometric distribution. The proof utilizes arguments of spectral gap and log Sobolev type.
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Curk, Tine. "Modelling multivalent interactons." Thesis, University of Cambridge, 2016. https://www.repository.cam.ac.uk/handle/1810/266916.
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A Multivalent entity, which could represent a protein, nanoparticle, polymer, virus or a lipid bilayer, has the ability to form multiple bonds to a substrate. Hence, a multivalent interaction can be strong, even if the individual bonds are weak. However, much more interestingly, multivalency enables the design of highly specific interactions using non-specific individual bonds. We attempt to rationalise multivalent effects using simple physical models complemented with numerical simulations. Based on physiochemical characteristics of multivalent binders, we aim to predict the overall strength of interaction and its sensitivity to variation in parameters. We start with a simple model of homo-multivalency, where all bonds are equivalent. Such systems can exhibit a super-selective response, which denotes the high sensitivity of the strength of multivalent binding to the number of accessible binding sites on the target surface. We present a theoretical analysis of systems of multivalent particles and show that a certain degree of disorder is necessary for super-selective behaviour. Moreover, we formulate a set of simple design rules for multivalent interactions that yield optimal selectivity. In the second stage, we expand the model to hetero-multivalency, accounting for multiple distinct types of binding partners. We consider targeting of cells based on a density profile of different membrane receptors types and demonstrate, that speci city towards a desired receptor density profile can be obtained. Hence, cells can be reliably targeted in the absence of specific markers. Crucially, we show that for optimal selectivity, individual bonds must be weak. Finally, we add information about specific geometry and positions of binding sites on the multivalent entity. We focus on molecular imprinting; the process whereby a polymer matrix is cross-linked in the presence of template molecules. The cross-linking process endows the polymer matrix with a chemical ‘memory’, such that the target molecules can subsequently be recognised by the matrix. We show how the binding multivalency and the polymer material properties affect the efficiency and selectivity of molecular imprinting.
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Whitehead, Thomas Michael. "Interacting Fermi gases." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274548.
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Interacting Fermi gases are one of the chief paradigms of condensed matter physics. They have been studied since the beginning of the development of quantum mechanics, but continue to produce surprises today. Recent experimental developments in the field of ultracold atomic gases, as well as conventional solid state materials, have produced new and exotic forms of Fermi gases, the theoretical understanding of which is still in its infancy. This Thesis aims to provide updated tools and additional insights into some of these systems, through the application of both numerical and analytical techniques. The first Part of this Thesis is concerned with the development of improved numerical tools for the study of interacting Fermi gases. These tools take the form of accurate model potentials for the dipolar and contact interactions, as found in various ultracold atomic gas experiments, and a new form of Jastrow correlation factor that interpolates between the radial symmetry of the inter-electron Coulomb potential at short inter-particle distances, and the symmetry of the numerical simulation cell at large separation. These methods are designed primarily for use in quantum Monte Carlo numerical calculations, and provide high accuracy along with considerable acceleration of simulations. The second Part shifts focus to an analytical analysis of spin-imbalanced Fermi gases with an attractive contact interaction. The spin-imbalanced Fermi gas is shown to be unstable to the formation of multi-particle instabilities, generalisations of a Cooper pair containing more than two fermions, and then a theory of superconductivity is built from these instabilities. This multi-particle superconductivity is shown to be energetically favourable over conventional superconducting phases in spin-imbalanced Fermi gases, and its unusual experimental consequences are discussed.
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Martins, Soraia Alexandra Araújo. "CD81 interacting proteins." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/16139.
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Mestrado em Biomedicina Molecular<br>Fertilization is a multistep and complex process culminating in the merge of gamete membranes, cytoplasmic unity and fusion of genome. CD81 is a tetraspanin protein that participates in sperm-oocyte interaction, being present at the oocyte surface. CD81 has also been implicated in other biological processes, however its specific function and molecular mechanisms of action remain to be elucidated. The interaction between CD81 and its binding partner proteins may underlie the CD81 involvement in a variety of cellular processes and modulate CD81/interactors specific functions. Interestingly, in a Yeast two Hybrid system previously performed in our lab, CD81 has emerged as a putative interactor of the Amyloid Precursor Protein (APP). In the work here described, bioinformatics analyses of CD81 interacting proteins were performed and the retrieved information used to construct a protein-protein interaction network, as well as to perform Gene Ontology enrichment analyses. CD81 expression was further evaluated in CHO, GC-1 and SH-SY5Y cell lines, and in human sperm cells. Additionally, its subcellular localization was analyzed in sperm cells and in the neuronal-like SH-SY5Y cell line. Subsequently, coimmunoprecipitation assays were performed in CHO and SH-SY5Y cells to attempt to prove the physical interaction between CD81 and APP. A functional interaction between these two proteins was accessed thought the analyses of the effects of CD81 overexpression on APP levels. A co-localization analysis of CD81 and some interactors proteins retrieved from the bioinformatics analyses, such as APP, AKT1 and cytoskeleton-related proteins, was also performed in sperm cells and in SH-SY5Y cells. The effects of CD81 in cytoskeleton remodeling was evaluated in SH-SY5Y cells through monitoring the effects of CD81 overexpression in actin and tubulin levels, and analyzing the colocalization between overexpressed CD81 and F-actin. Our results showed that CD81 is expressed in all cell lines tested, and also provided the first evidence of the presence of CD81 in human sperm cells. CD81 immunoreactivity was predominantly detected in the sperm head, including the acrosome membrane, and in the midpiece, where it co-localized with APP, as well as in the post-acrosomal region. Furthermore, CD81 co-localizes with APP in the plasma membrane and in cellular projections in SH-SY5Y cells, where CD81 overexpression has an influence on APP levels, also visible in CHO cells. The analysis of CD81 interacting proteins such as AKT1 and cytoskeletonrelated proteins showed that CD81 is involved in a variety of pathways that may underlie cytoskeleton remodeling events, related to processes such as sperm motility, cell migration and neuritogenesis. These results deepen our understanding on the functions of CD81 and some of its interactors in sperm and neuronal cells.<br>A fecundação é um processo complexo e faseado que culmina na fusão celular das membranas dos gametas, do citoplasma e do genoma. A CD81 é uma proteína tetraspanina que participa na interacção espermatozóide-oócito, estando presente na superfície do oócito. A CD81 também tem sido associada a outros processos biológicos, contudo a sua função específica e os seus mecanismos de acção não estão elucidados. A ligação entre a CD81 e as suas proteínas interactoras fundamenta o envolvimento da CD81 numa variedade de processos celulares e funções específicas. O desenvolvimento de um sistema de Dois Híbrido em Leveduras, anteriormente realizado no nosso laboratório, mostrou que a CD81 potencialmente interage com a Proteína Percursora de Amilóide (PPA). No presente trabalho, foi realizada a análise bioinformática das proteínas interactoras da CD81. A informação obtida permitiu a construção de uma rede de interações proteína-proteína, bem como a análise de enrequecimento de Ontologia de Genes. Adicionalmente, a expressão da CD81 foi avaliada nas linhas celulares CHO, GC-1 e SH-SY5Y e em espermatozóides humanos. A sua localização subcelular foi também analisada em espermatozóides humanos e na linha de neuroblastoma SH-SY5Y. Foram ainda realizados ensaios de coimunoprecipitacão nas linhas celulares CHO e SH-SY5Y, com a tentativa de provar a intercação física entre a CD81 e a PPA. A interação funcional entre estas duas proteínas foi estudada através da análise do efeito da sobreexpressão da CD81 nos níveis de PPA. Foram também realizados estudos de colocalização entre a CD81 e algumas proteínas interactoras, nos espermatozóides humanos e na linha celular SH-SY5Y. Os interatores analisados, PPA, AKT1 e proteínas relacionadas com o citoesqueleto, foram obtidos da análise bioinformática previamente realizada. O efeito da CD81 na remodelação do citoesqueleto foi avaliado através da monitorização dos efeitos da sobre-expressão da CD81 nos níveis de actina e tubulina, bem como através da análise da colocalização entre a CD81 sobre-expressa e a F-actina. Os nossos resultados mostram que a CD81 está expressa em todas as linhas celulares testadas, providenciando a primeira evidência da presença da CD81 em espermatozóides humanos. A marcação da CD81 foi predominantemente detectada na cabeça do espermatozóde e na peça intermédia, onde colocaliza com a PPA, bem como na região pós-acrossómica. Em adição, a CD81 colocaliza com a PPA na membrana plasmática e nas projecções celulares das células SH-SY5Y, onde a sobre-expressão da CD81 influencia os níveis de PPA, efeito também observado nas células CHO. A análise de proteínas interactoras da CD81, como a AKT1 e proteínas relacionadas com o citoesqueleto, evidenciou que a CD81 está envolvida na remodelação do citoesqueleto, nomeadamente na motilidade dos espermatozóides, na migração celular e na neuritogénese. Estes resultados permitiram aprofundar o conhecimento das funções da CD81 e de alguns dos seus interactores, em espermatozóides e em células neuronais.
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Boring, Sebastian. "Interacting "Through the Display"." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-118188.
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Hutzenthaler, Martin. "Interacting locally regulated diffusions." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=985500492.
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Omojokun, Olufisayo Dewan Prasun. "Interacting with networked devices." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,174.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2006.<br>Title from electronic title page (viewed Oct. 10, 2007). " ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Computer Science." Discipline: Computer Science; Department/School: Computer Science.
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Barr, Joshua. "Transport in Interacting Nanostructures." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301551.
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Transport through nanostructures is studied at the many-body level using exact diagonalization and nonequilibrium Green's functions. Organic molecular junctions are a particular focus because of their technological promise. Work is presented regarding: (1) A π-electron model of organic molecular junctions developed using effective field theory; (2) series transmission and transmission node structure in interacting systems; (3) the effect of interactions on quantum interference and thermoelectricity in polycyclic junctions; and (4) nanoscale transport calculations using self-consistent statistical ensembles.
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Williams, Ceri Rhys. "Quantum interacting branching systems." Thesis, University of Nottingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416728.
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Huang, S. N. "Dynamics of interacting galaxies." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378332.
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Gracar, Peter. "Random interacting particle systems." Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.761028.
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Consider the graph induced by Z^d, equipped with uniformly elliptic random conductances on the edges. At time 0, place a Poisson point process of particles on Z^d and let them perform independent simple random walks with jump probabilities proportional to the conductances. It is well known that without conductances (i.e., all conductances equal to 1), an infection started from the origin and transmitted between particles that share a site spreads in all directions with positive speed. We show that a local mixing result holds for random conductance graphs and prove the existence of a special percolation structure called the Lipschitz surface. Using this structure, we show that in the setup of particles on a uniformly elliptic graph, an infection also spreads with positive speed in any direction. We prove the robustness of the framework by extending the result to infection with recovery, where we show positive speed and that the infection survives indefinitely with positive probability.
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Concannon, Edmond Paul. "Hyperpolarizabilities of interacting atoms." Thesis, University of Cambridge, 1996. https://www.repository.cam.ac.uk/handle/1810/283712.
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Ku, Ho Ming. "Interacting Markov branching processes." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2002759/.
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In engineering, biology and physics, in many systems, the particles or members give birth and die through time. These systems can be modeled by continuoustime Markov Chains and Markov Processes. Applications of Markov Processes are investigated by many scientists, Jagers [1975] for example . In ordinary Markov branching processes, each particles or members are assumed to be identical and independent. However, in some cases, each two members of the species may interact/collide together to give new birth. In considering these cases, we need to have some more general processes. We may use collision branching processes to model such systems. Then, in order to consider an even more general model, i.e. each particles can have branching and collision effect. In this case the branching component and collision component will have an interaction effect. We consider this model as interacting branching collision processes. In this thesis, in Chapter 1, we firstly look at some background, basic concepts of continuous-time Markov Chains and ordinary Markov branching processes. After revising some basic concepts and models, we look into more complicated models, collision branching processes and interacting branching collision processes. In Chapter 2, for collision branching processes, we investigate the basic properties, criteria of uniqueness, and explicit expressions for the extinction probability and the expected/mean extinction time and expected/mean explosion time. In Chapter 3, for interacting branching collision processes, similar to the structure in last chapter, we investigate the basic properties, criteria of uniqueness. Because of the more complicated model settings, a lot more details are required in considering the extinction probability. We will divide this section into several parts and consider the extinction probability under different cases and assumptions. After considering the extinction probability for the interacting branching processes, we notice that the explicit form of the extinction probability may be too complicated. In the last part of Chapter 3, we discuss the asymptotic behavior for the extinction probability of the interacting branching collision processes. In Chapter 4, we look at a related but still important branching model, Markov branching processes with immigration, emigration and resurrection. We investigate the basic properties, criteria of uniqueness. The most interesting part is that we investigate the extinction probability with our technique/methods using in Chapter 4. This can also be served as a good example of the methods introducing in Chapter 3. In Chapter 5, we look at two interacting branching models, One is interacting collision process with immigration, emigration and resurrection. The other one is interacting branching collision processes with immigration, emigration and resurrection. we investigate the basic properties, criteria of uniqueness and extinction probability. My original material starts from Chapter 4. The model used in chapter 4 were introduced by Li and Liu [2011]. In Li and Liu [2011], some calculation in cases of extinction probability evaluation were not strictly defined. My contribution focuses on the extinction probability evaluation and discussing the asymptotic behavior for the extinction probability in Chapter 4. A paper for this model will be submitted in this year. While two interacting branching models are discussed in Chapter 5. Some important properties for the two models are studied in detail.
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Kantamneni, Sriharsha. "Identification and characterisation of proteins interacting with novel GABAβ receptor interacting scaffold protein (GISP)." Thesis, University of Bristol, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412275.
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Weibrecht, Irene. "Visualizing Interacting Biomolecules In Situ." Doctoral thesis, Uppsala universitet, Molekylära verktyg, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-151579.
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Intra- and intercellular information is communicated by posttranslational modifications (PTMs) and protein-protein interactions, transducing information over cell membranes and to the nucleus. A cells capability to respond to stimuli by several highly complex and dynamic signaling networks provides the basis for rapid responses and is fundamental for the cellular collaborations required in a multicellular organism. Having received diverse stimuli, being positioned at various stages of the cell cycle or, for the case of cancer, containing altered genetic background, each cell in a population is slightly different from its neighbor. However, bulk analyses of interactions will only reveal an average, but not the true variation within a population. Thus studies of interacting endogenous biomolecules in situ are essential to acquire a comprehensive view of cellular functions and communication. In situ proximity ligation assay (in situ PLA) was developed to investigate individual endogenous protein-protein interactions in fixed cells and tissues and was later applied for detection for PTMs. Progression of signals in a pathway can branch out in different directions and induce expression of different target genes. Hence simultaneous measurement of protein activity and gene expression provides a tool to determine the balance and progression of these signaling events. To obtain this in situ PLA was combined with padlock probes, providing an assay that can interrogate both PTMs and mRNA expression at a single cell level. Thereby different nodes of the signaling pathway as well as drug effects on different types of molecules could be investigated simultaneously. In addition to regulation of gene expression, protein-DNA interactions present a mechanism to manage accessibility of the genomic DNA in an inheritable manner, providing the basis for lineage commitment, via e.g. histone PTMs. To enable analyses of protein-DNA interactions in situ we developed a method that utilizes the proximity dependence of PLA and the sequence selectivity of padlock probes. This thesis presents new methods providing researchers with a set of tools to address cellular functions and communication in complex microenvironments, to improve disease diagnostics and to contribute to hopefully finding cures.
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Mujal, Torreblanca Pere. "Interacting ultracold few-boson systems." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668191.
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In this thesis, we study the physical properties of several ultracold few-boson systems depending on the interactions between their constituents. Nowadays, experimentally, it is possible to have great control with high precision over the geometry and the interactions between the particles, making them an excellent setup to test directly the principles of quantum mechanics. A very interesting point is to study the evolution of their properties with the number of particles. The theoretical study of these systems pretends to microscopically understand the current experimental results and give support to new experimental developments.
The method that will be used is the exact diagonalization of the Hamiltonian of the system. As we will see, in spite of the attempts to improve it, the method is limited by the fact that, in practice, it is only useful to study few-particle systems. The method has several advantages. First of all, one has access to both the ground and the excited states. In second place, the method is variational and converges to the exact solution as long as the Hilbert space in which we diagonalize is enlarged.
Moreover, since we have access to the states of the system, it is possible to calculate any observable quantity of interest.
First, we will study a system of spinless bosons trapped in a two-dimensional harmonic potential. The effect of the trap is to keep the system bound. It will be seen how the presence of a repulsive interaction changes the energy spectrum and other properties of the system. For instance, the density profile, which is usually measurable, and also the two-body distribution function, which is intimately related to the existence of correlations.
Afterwards, the focus will be on the particular case of having only two bosons in the system interacting through a strong repulsive force. Inspired by the one-dimensional case where the fermionization phenomenon takes place in the strongly-interacting limit, we will study whether in two dimensions there is a resembling reminiscent effect. In other words, we will analyze if there are properties of the two strongly-interacting bosons in two dimensions that are like the ones of two noninteracting fermions.
After that, we will tackle the localization phenomenon in a one-dimensional system that is caused by an external speckle potential that introduces disorder in the system. We will show that the localization is a robust phenomenon against repulsive contact interactions.
Finally, we will study the influence of the spin-orbit coupling in a system of bosons with two possible pseudospin components, associated, for instance, to two hyperfine levels, confined in a two-dimensional harmonic trap. We will present an exhaustive analysis of the combined effects of the interaction and the spin-orbit coupling in the spectrum and the properties of the system. In particular we show the existence of a crossover in the ground state of the system susceptible to be experimentally identified.<br>En aquesta tesi, estudiarem les propietats físiques de diversos sistemes de pocs bosons ultrafreds depenent de les interaccions entre els seus constituents. Avui dia, a nivell experimental, es té un gran control amb una gran precisió de la geometria i les interaccions entre les partícules, fet que fa aquest sistemes excel·lents per comprovar de forma directa els principis de la mecànica quàntica. Un punt d'interès és comprovar l'evolució de les seves propietats amb el nombre de partícules.
L'estudi teòric d'aquests sistemes pretén entendre a nivell microscòpic els resultats experimentals actuals i donar suport pels nous avenços experimentals.
El mètode que farem servir serà la diagonalització exacta del hamiltonià del sistema. Com veurem, malgrat les millores que es poden implementar, ens trobarem amb la limitació de no poder estudiar sistemes de més d'unes quantes partícules. Els avantatges d'aquest mètode són diversos. En primer lloc, podrem obtenir no només l'estat fonamental del sistema sinó que també els primers estats excitats. En segon lloc, el mètode és variacional i sabem que convergeix cap a la solució exacta a mesura que ampliem l'espai de Hilbert en que diagonalitzem. A més a més, en tenir accés als estats del sistema, podem calcular qualsevol quantitat observable que sigui d'interès.
Primerament, estudiarem un sistema de bosons sense espín atrapats en un potencial harmònic bidimensional. L'efecte de la trampa és de mantenir el sistema lligat. En haver-hi una interacció repulsiva, veurem com canvia l'espectre d'energia del sistema i també altres propietats. Per exemple, la seva densitat, que habitualment es pot mesurar, i també la funció de distribució de dos cossos, que va íntimament lligada a l'existència de correlacions.
Tot seguit, ens centrarem en el cas particular de tenir només dos bosons en el sistema interaccionant a través d'una gran força repulsiva. Inspirats pel cas unidimensional en que té lloc el fenomen de la fermionització en el limit d'interacció molt forta, estudiarem si en el cas bidimensional hi queda cap reminiscència d'aquest efecte. En altres paraules, analitzarem si hi ha propietats dels dos bosons fortament interactuants en dues dimensions que siguin com les de fermions no interactuants en el mateix sistema.
A continuació, tractarem el fenomen de la localització en un sistema unidimensional en el qual hi ha un potencial extern de tipus speckle que introdueix desordre en el sistema. Veurem que la localització és un fenomen robust en front de les interaccions repulsives.
Per últim, estudiarem la influència de l'espín-òrbita en un sistema de bosons amb dues components de pseudoespín, associades, per exemple, a dos nivells hiperfins, atrapats en un potencial harmònic bidimensional. Presentarem un anàlisi exhaustiu dels efectes conjunts de la interacció i l'espín- òrbita en l'espectre i en les propietats del sistema. En particular, mostrarem l'existència d'un encreuament en l'estat fonamental del sistema susceptible de ser identificat experimentalment.
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Winter, Sherry Lynn. "Identification of BRCA1 interacting proteins." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0026/MQ50432.pdf.
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Zhu, Ming. "Molecular gas in interacting galaxies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58915.pdf.
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Borowicz, Jolanta J. "Traits of biologically interacting pseudomonads /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1998. http://epsilon.slu.se/avh/1998/91-576-5452-2.gif.
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Saha, Sudarshana. "Interacting states in polyatomic molecules." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.495804.
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This work investigates interacting states in polyatomic molecules, concentrating on two examples, the analysis of interacting states in the linear C3 radical and the study of perturbations resulting from interacting states in Formaldehyde. Work on the C₃ radical started with ab initio potential energy surface calculations to outline the lowest 8 singlet electronic states, followed by vibrational energy level calculations corresponding to these electronic states. On the experimental front, the vibronic states of the radical were probed by laser spectroscopy, particularly by double resonance techniques.
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Cullen, H. E. "The physics of interacting galaxies." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598207.
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This thesis investigates interacting galaxies using two complementary approaches: a statistical study of star formation in a large sample of close pairs of galaxies drawn from the Sloan Digital Sky Survey (SDSS) and a study of the ISM and star forming properties of a small sample of interacting pairs taken from Arp’s atlas, each comprising one early- and one late-type system (E+S pairs). The first part of this thesis investigates the effect of galaxy interaction on star formation using a large volume- and luminosity-limited sample of galaxies drawn from the SDSS. Star-formation rates were calculated from extinction and aperture corrected Hα luminosities and, for a subset of systems, <i>IRAS </i>data. The mean specific star-formation rate is found to be strongly enhanced for projected separations of less than 25 kpc. For late-type galaxies, the correlation extends out to projected separations of 300 kpc and is most pronounced in actively star-forming systems. The specific star-formation rate of observed to decrease with increasing recessional velocity difference, although the magnitude of this effect is small compared to that associated with the projected separation. No dependence of star formation enhancement on the morphological type or mass of the companion galaxy is observed. This second part of this thesis presents a study of the ISM and star forming properties of nine E+S pairs. Detailed case studies were undertaken for two of the pairs, Arp 140 and Arp 104, both of which display extended tidal tails in their H1 morphology. These two pairs differ markedly. Despite Arp 140’s relatively evolved interaction and weakly barred potential, NGC 275, the late-type component, has neither a molecular gas nor star formation distribution that is centrally condensed. Instead, the molecular gas and HII regions display an unusual anti-correlation.
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Pangon, Laurent Luc Gilles. "BRCA1 N-terminal interacting partners." Thesis, King's College London (University of London), 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486355.
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The product of the breast and ovarian cancer predisposition gene, BRCAI, is a large protein with two main recognised motifs; the N-terrninal RING and C-terrninal BRCT. The N-tenninus has been reported to interact with at least eight proteins (MSH2, ATFI, ERalpha, BAPI, p300, NPMlB23, UbcH5A and BARDI). In order to test the relevance of these interacting partners to the BRCAI tumour suppressor activity, we intended to test patient derived missense variants upon each interaction. We found that of the eight potential partners, only BARDI and the ubiquitin conjugating enzyme UbcH5A interacted with the BRCAI N-terrninal region, by yeast two-hybrid assays. The BRCAI/UbcH5A interaction was also confirmed in mammalian cells by FRET analysis. To determine }Vhether these interactions, or their abrogation, might fonn part of the BRCAI-mediated tumorigenesis pathway we undertook an extensive mutagenesis study. Our results show that all known pathogenic missense mutations and the majority ofBRCAI N-terrninal unclassified variants, found in populations enriched for family history ofdisease, weakened or abolished the BRCAI/UbcH5A interaction. Loss of ubiquitin ligase activity measured biochemically, and in cells, correlated with BRCAI/UbcH5A disruption. Finally, in silico prediction, based on evolutionary conservation and protein structural analysis supported and complemented our mutagenesis results. Overall, our data provide functional evidence that the BRCAI/UbcH5A interaction is highly sensitive to missense substitution and suggest that the ubiquitin pathway is likely to play an important role in BRCAI-mediated tumorigenesis. Even though we could not detect a direct interaction between BRCAI and MSH2, our study on MSH2-deficient primary human cells implicated MSH2 in the homologous recombination repair pathway.
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Baakdah, Fadi. "Identification of PfCRT interacting proteins." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121534.
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The lethal form of human malaria is caused by the most prominent human protozoan parasite, Plasmodium falciparum, responsible for an estimated ~1 million deaths annually. Malaria treatment and, prevention heavily rely on antimalarial drugs. The synthetic substitute of quinine, chloroquine, was the most effective treatment for this disease. The rise of chloroquine resistant malaria in endemic areas has suppressed control efforts. Chloroquine resistance has been associated with mutations in a transmembrane protein on the digestive vacuole of the parasite, designated PfCRT. Moreover, the normal function(s) and natural substrate(s) of PfCRT remain a matter of speculation as direct evidence for the normal functions or substrates are yet to be determined. The objectives of this thesis are to develop and characterize two antisera to the N- and C termini of PfCRT as tools for the identification of PfCRT interacting proteins in P. falciparum. Although the molecular mass of PfCRT was estimated as 48.67 kDa, immunobiochemical characterizations using different antiserums raised against the N- and C-cytosolic domains of this protein throughout the published literature yielded varying molecular masses of PfCRT on SDS PAGE. In this thesis, we report the generation and biochemical characterization of two antisera raised against the N- and C-cytosolic domains of PfCRT. Our results show PfCRT-C antiserum to detect non-phosphorylated epitopes or sequences in PfCRT. Moreover, our high-resolution epitope mapping results confirm the specificity of PfCRT-C antiserum to a non-phosphorylated form of PfCRT and show that phosphorylation at two sites in PfCRT sequence, Ser411 and Thr416, prevent its binding to the full-length and phosphorylated protein. In addition, we have identified a novel truncated form of PfCRT that is both unphosphorylated, as it is recognized by PfCRT-C antiserum, and likely to represent a differentially spliced product of PfCRT, that is expressed in vivo on the parasite digestive vacuole. Furthermore, our findings confirm the molecular mass of the full-length and phosphorylated PfCRT as a 52 kDa protein band on SDS PAGE. Using PfCRT antisera together with three different methods of protein interactions, we provide the first evidence of proteins interacting with PfCRT. Identification of these proteins which ranges from ~20 kDa to 200 kDa is under active investigation.<br>La forme létale du paludisme humain est causée par le plus important parasite protozoaire humain, Plasmodium falciparum, responsable d'environ ~1 million de mort annuellement. Le traitement et la prévention du paludisme dépend des médicaments antipaludiques. Le substitut synthétique de la quinine, la chloroquine, était le traitement le plus efficace pour cette maladie. La montée du paludisme résistant à la chloroquine dans les pays endémiques a supprimé les efforts de contrôle. La résistance à la chloroquine a été associée aux mutations dans la protéine transmembranaire présente sur la vacuole digestive du parasite, désigné PfCRT. De plus, la ou les fonctions normales et substrats naturels de la protéine PfCRT restent une affaire de spéculation étant donné qu'une évidence directe des fonctions normales et des substrats de cette protéine sont encore à déterminer. Les objectives de cette thèse sont de développer et de caractériser deux antisérums de l'extrémité N- et C-terminale de PfCRT comme outils d'identification des protéines interagissant avec la protéine PfCRT de P. falciparum. Bien que la masse moléculaire de la protéine PfCRT était estimée à 48.67 kDa, des caractérisations immunobiochimiques utilisant différents antisérums dirigés contre les domaines cytosoliques N- et C-terminal de cette protéine et publiés à travers la littérature ont abouti à des masses moléculaires variable de la protéine PfCRT sur le SDS PAGE. Dans cette thèse, nous reportons la génération et la caractérisation biochimique de deux antisérums dirigés contre les domaines cytosoliques N- et C de PfCRT. Nos résultats montrent que l'antisérum C de PfCRT détecte les épitopes non-phosphorylés ou des séquences dans la protéine PfCRT. En outre, nos résultats de la cartographie à haute résolution de l'épitope confirment la spécificité de l'antisérum C de PfCRT à la forme non-phosphorylé de PfCRT et montrent que la phosphorylation à deux sites au niveau de la séquence de la protéine, Ser411 et Thr416, qui empêche sa fixation à la protéine complète et phosphorylée. De plus, nous avons identifié une nouvelle forme tronquée de PfCRT qui est à la fois phosphorylée puisqu'elle est reconnue par l'antisérum C de PfCRT, et susceptible de représenter un produit différemment épissé de PfCRT, qui est exprimé in vivo sur la vacuole digestive du parasite. En outre, nos résultats confirment la masse moléculaire de la protéine complète et phosphorylée de PfCRT à 52 kDa sur un SDS PAGE. En utilisant les antisérums de PfCRT combiné à trois méthodes différentes d'interactions protéiques, nous fournissons la première preuve de protéines interagissant avec la protéine PfCRT. L'identification de ces protéines dont la masse varie entre ~20 kDa et 200 kDa est sous enquête active.
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Jackson, Michael John. "Interacting with semi-automated theorem." Thesis, Edinburgh Napier University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286206.
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Marston, A. P. "Observational aspects of interacting galaxies." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382762.
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Zhang, Hui. "Physically interacting with four dimensions." [Bloomington, Ind.] : Indiana University, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3344615.
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Thesis (Ph.D.)--Indiana University, Dept. of Computer Science, 2009.<br>Title from PDF t.p. (viewed on Oct. 8, 2009). Source: Dissertation Abstracts International, Volume: 70-02, Section: B, page: 1147. Adviser: Andrew J. Hanson.
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Wright, G. S. "Infrared activity in interacting galaxies." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/46917.
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Sadofyev, Andrey V. "Probes of strongly interacting plasma." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112072.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2017.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 123-138).<br>In this thesis we discuss recent results on the medium/probe interaction in the strongly coupled plasma produced in heavy-ion collisions. Such processes involve physics at multiple energy scales making a consistent theoretical description challenging. We show how insights from various regimes can be combined to extend our understanding of the underlying physics. As a first example, we start with the novel contributions to the drag force acting on a heavy quark moving through the strongly coupled holographic plasma. The new terms are proportional to the coefficient of the axial anomaly and to the chiral asymmetry in the medium. These chiral contributions to the drag force act either parallel to or antiparallel to an external magnetic field or to the vorticity of the fluid. We show that the chiral drag force vanishes for heavy quarks that are at rest in a suitably chosen frame in the weak field limit. In this frame, the heavy quark at rest sees counter propagating momentum and charge currents, both proportional to the axial anomaly coefficient, but feels no drag force. This provides strong concrete evidence for the absence of dissipation in chiral transport. Then, we extend this result introducing a concept of an "anomalous wind" felt by probes at rest. This phenomenon modifies previous results on the medium/probe interaction. We demonstrate that by deriving the anomalous correction to the screening length of the heavy quarkonium color potential. Finally, we discuss the strong magnetic field limit to the leading order in the weak medium/probe coupling. It is shown that the drag force is suppressed along the magnetic field and in the exact chiral limit tends to zero. This anisotropy in the drag force is present in the system even at zero chiral asymmetry and may lead to strong observable effects. Then, we turn to the main available probes of the plasma produced in experiments - jets. We supplement the holographic description corresponding to the infinite medium/probe coupling limit with an initial parameter distribution for an ensemble of jets motivated by the weakly coupled dynamics and similar to the case of proton-proton collisions. The model constructed in this way, combining insights from both weakly and strongly coupled regimes, is used to analyze the evolution of an ensemble, as it propagates through an expanding cooling droplet of strongly coupled plasma as in heavy ion collisions. Each jet in the ensemble is represented holographically by a string in the dual 4 + 1-dimensional gravitational theory. Firstly, the full string dynamics is approximated by assuming that the string moves at the speed of light. We study the evolution of the jet opening angle distribution upon propagating the droplet and study the medium effect on the mean opening angle within a simple two parametric phenomenological model. Then, we extend this result analyzing the full string dynamics for a range of possible initial conditions. That gives access to the dynamics of holographic jets just after their creation. We analyze the full jet shape modification and find the result that the jet shape scales with the opening angle at any particular energy. Further, we construct an ensemble of dijets with energies and energy asymmetry distributions taken from events in proton-proton collisions and jet shape taken from proton-proton collisions and scaled according to our result. We study how these observables are modified after the ensemble of dijets is propagated through the strongly-coupled plasma. The results of this simple model is in qualitative agreement with the experimental data.<br>by Andrey V. Sadofyev.<br>Ph. D.
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Allais, Andrea. "Interacting fermions : a holographic approach/." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/83828.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2013.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (page 59).<br>Most materials are either metals or insulators. When they are metals, their electronic properties are usually described by Landau's Fermi liquid theory. That is, they behave more or less like a free Fermi gas, with a few modifications due to electron-electron interactions. However, there exist a few metallic materials whose phenomenology does not fit within Fermi liquid theory. These are quasi-2D metals on the verge of becoming insulators, and they happen to become superconducting at low temperature, by a mechanism different than BCS superconductivity. The physics of these materials calls for a new strongly coupled universality class of interacting electrons, yet to be understood. This work looks at the problem from the novel point of view of gauge/gravity, or holographic, duality.<br>by Andrea Allais.<br>Ph.D.
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Dickison, Mark E. "Dynamic and interacting complex networks." Thesis, Boston University, 2012. https://hdl.handle.net/2144/31536.
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Thesis (Ph.D.)--Boston University<br>PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.<br>This thesis employs methods of statistical mechanics and numerical simulations to study some aspects of dynamic and interacting complex networks. The mapping of various social and physical phenomena to complex networks has been a rich field in the past few decades. Subjects as broad as petroleum engineering, scientific collaborations, and the structure of the internet have all been analyzed in a network physics context, with useful and universal results. In the first chapter we introduce basic concepts in networks, including the two types of network configurations that are studied and the statistical physics and epidemiological models that form the framework of the network research, as well as covering various previously-derived results in network theory that are used in the work in the following chapters.
In the second chapter we introduce a model for dynamic networks, where the links or the strengths of the links change over time. We solve the model by mapping dynamic networks to the problem of directed percolation, where the direction corresponds to the time evolution of the network. We show that the dynamic network undergoes a percolation phase transition at a critical concentration Pc, that decreases with the rate r at which the network links are changed. The behavior near criticality is universal and independent of r. We find that for dynamic random networks fundamental laws are changed: i) The size of the giant component at criticality scales with the network size N for all values of r, rather than as N^(2/3) in static network, ii) In the presence of a broad distribution of disorder, the optimal path length between two nodes in a dynamic network scales as N^(1/2), compared to N^(1/3) in a static network.
The third chapter consists of a study of the effect of quarantine on the propagation of epidemics on an adaptive network of social contacts. For this purpose, we analyze the susceptible-infected-recovered model in the presence of quarantine, where susceptible individuals protect themselves by disconnecting their links to infected neighbors with probability w and reconnecting them to other susceptible individuals chosen at random. Starting from a single infected individual, we show by an analytical approach and simulations that there is a phase transition at a critical rewiring (quarantine) threshold We separating a phase (w < wc) where the disease reaches a large fraction of the population from a phase (w > wc) where the disease does not spread out. We find that in our model the topology of the network strongly affects the size of the propagation and that wc increases with the mean degree and heterogeneity of the network. We also find that wc is reduced if we perform a preferential rewiring, in which the rewiring probability is proportional to the degree of infected nodes.
In the fourth chapter, we study epidemic processes on interconnected network systems, and find two distinct regimes. In strongly-coupled network systems, epidemics occur simultaneously across the entire system at a critical value f3e· In contrast, in weakly-coupled network systems, a mixed phase exists below f3e, where an epidemic occurs in one network but does not spread to the coupled network. We derive an expression for the network and disease parameters that allow this mixed phase and verify it numerically. Public health implications of communities comprising these two classes of network systems are also mentioned.<br>2031-01-01
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Wiranata, Anton. "Transport Coefficients of Interacting Hadrons." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1314733650.
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Petridis, Panagiotis. "Interacting with Digital Heritage Systems." Thesis, University of Sussex, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487090.
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Cabral, de Barros Susana Cristina. "ULTRACAM observations of interacting binaries." Thesis, University of Warwick, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491889.
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This thesis focuses upon two different aspects of interacting binary stars, the study of the shortest period binary stars known V407 Vul and HM Cnc and the study of stochastic variability in cataclysmic variable stars. V407 Vul and HM Cnc are X-ray emitting stars with X-ray and optical light curves that are modulated on periods of 569 and 321 s, respectively. In chapter 4 we consider geometrical constraints upon the unipolar inductor model for these stars, in particular what parameter values (component masses, orbital inclination and magnetic colatitude) can describe the X-ray and optical light curves. We find that for a dipole field on the primary star, the unipolar inductor model fails to match the data on V407 Vul for any combin?tion of parameters, and can' only match HM Cnc if the sparser set of observations of this star have been unluckily timed. In chapter 5 we present optical light curves of V407 Vul and HM Cnc. The optical and X-ray light curves of HM Cnc have been reported as being in antiphase, but we find that in fact the X-rays peak around 0.2 cycles after the maximum of the optical light, as seen also in V407 Vul. The X-rayjoptical phase shifts are well explained under the accreting models of the systems if most of the optical modulation comes from the heated faces of the mass donors and if the X-ray emitting spots are positioned in advance of the mass donors, as is expected given the angular momentum of the accreting XIV l II , Supplied by The British Library - 'The world's knowledge' 1 material. Some optical emission may also come from the vicinity of the X-ray spot. and we further show that this can explain the non-sinusoidal light curves of HM Cnc. The only significant difference between the two stars is that V407 Vul is observed to have the spectrum of a G star. The variation in position on the sky of a blend of a variable and a constant star can be used as a measure of their separation. and is sensitive to values well below the limit set by seeing. We apply this 'pulsation astrometry' to deduce that .the G star is separated from the variable by about 0.027 arcsec and hence plays no role in the vadability of V407 Vul. We show that light travel time variations could influence the period change in V407 Vul if it forms a triple system with the G star. In chapter 6 we present the study of flickering. Flickering is a characteristic of accreting systems. It is thought that the maximum frequency present in an accretion disc is the dynamic frequency at the inner accretion disc radius. In cataclysmic variable stars this would appear as a break in the power spectrum on frequencies 0.01 - 3 Hz. We use the high speed CCD Camera ULTRACAM to obtain high time resolution data on 14 cataclysmic variables in the hope of seeing the expected break in their power spectrum. We did not find such a break because the power spectra of the cataclysmic variable stars observed was steeper than was expected. We measure a power spectrum proportional to j-2.5 while previous studies reported it to be proportional to j-2. We compared flickering in cataclysmic variable stars with stellar flares and concluded that they have the same colour behaviour so they have could the same origin Le. magnetic reconnection. We also compare the power spectra of cataclysmic variable stars and of X-ray binaries in the optical and concluded that the latter are much shallower than cataclysmic variable stars. We argue that this implies that flickering in X-ray transients comes from the inner accretion disc in both systems since their outer discs are thought to be similar. Supplied by The British Library - 'The world's knowledge'
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Sánchez, García Elsa. "Computational study of weakly interacting complexes." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=981165893.
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Naab, Thorsten. "Structure and dynamics of interacting galaxies." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961763744.
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Pinnow, Henryk A. "Field theory of interacting crumpled manifolds." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=96624687X.
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Widén, Christina. "Studies of glucocorticoid receptor interacting proteins /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-322-1/.
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Hu, Xiao Wooten Marie W. "Analysis of P62-UBA interacting proteins." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/master's/HU_XIAO_49.pdf.
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Nairn, C. M. C. "Theory of interacting plasmas in space." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233541.
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Mehta, A. "Scaling approaches to interacting walk models." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370291.
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Stocks, Matthew Benedict. "Interacting with biomolecules using haptic feedback." Thesis, University of East Anglia, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539370.
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Ahmed, Nader Wahba Abdelrahman. "TspA interacting proteins of Neisseria meningitidis." Thesis, University of Nottingham, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556164.
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Neisseria meningitidis is a commensal bacterium of the human nasopharynx. Occasionally, it gains access to the bloodstream and causes septicaemia and subsequently meningitis. T-cell stimulating protein A (TspA) is an immunogenic, conserved, T -cell and B-cell stimulating protein of N meningitidis that is required for optimal adhesion to human cells. The role of TspA in the adhesion process is thought to be indirect since it is predicted that the N-terminus is localised to the periplasmic space with an inner membrane- spanning domain linking it to a cytoplasmic C-terminal domain; the aim of this study was to identify proteins within the meningococcal envelope that interact with TspA. Four overlapping recombinant fragments of TspA were expressed and purified as fusion proteins with the pGEX-2T-encoded glutathione-S- transferase protein and pQE70. A receptor activity-directed affinity tagging protocol was employed to identify TspA-interacting meningococcal proteins. Interactions between TspA and candidate proteins were investigated further using ELISA and surface plasmon resonance. Four putative TspA-interacting proteins were identified: PilQ and PilT (components of the type IV pilus machinery); the major outer membrane protein, PorA, and the protein chaperone, ClpB. Furthermore, the portion of TspA responsible for interaction with PorA was confirmed to be the N- terminus. Together, findings show that periplasmic domains of TspA interact with several outer membrane proteins which have a key role in meningococcal pathogenesis and adhesion to host cells.
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Heaney, Libby. "Entanglement of non-interacting Bose gases." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491808.
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Entanglement in many-body systems of identical particles often resides between modes of the field occupied by particles rather than between the particles themselves, or their internal degrees of freedom. Spatial field modes are an important choice of modes and investigating entanglement between them for a non-interacting Bose gas is the concern of this thesis. A particularly interesting phase of a Bose gas is a Bose-Einstein condensate (BEC). Long-range correlations between all points in space exist in a BEC, which are detected by the single-particle reduced density matrix.
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Robertson, David. "Transverse oscillations of interacting coronal loops." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.538010.
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Glass, K. "Dynamics of systems of interacting particles." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599435.
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In this thesis, we bring together three different problems in studying the equations where u<I><SUB>i</SUB></I> is a vector of length <I>m</I>, and <I>β</I> is a real parameter restricted to <I>β </I>≥ -1. The <I>N</I>-body problem concerns <I>N</I> masses attracting one another according to a (1)/(<I>r<SUP>2</SUP></I>) gravitational force. Much work has been done in finding <I>central configurations </I>of the <I>N</I> masses. If a system of masses released from a central configuration, it will remain similar to itself for all time, and can exhibit periodic behaviour.