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1
Zheng, Shu M. Eng Massachusetts Institute of Technology. "Electrical stimulation of the ventral lateral periaqueductal gray induces antinociception in rats". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91885.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 40-42).
Despite the central role of general anesthesia in modern healthcare, the frequency of anesthesia-related morbidity resulting from the toxicity and non-specificity of anesthetic drugs remains high. Among the key behavioral states of general anesthesia is antinociception (reduced sensitivity to pain). Within the nociceptive pathway in the brain and the central nervous system, the periaqueductal gray (PAG) has been shown to be a key site that modulates antinociception responses. We hypothesize that electrical stimulation of the ventral lateral periaqueductal gray (vIPAG) in rodents reliably induces antinociception in a physiology-derived way. Rectangular electrical stimuli were applied at the vlPAG of rats at animal-specific optimal currents. We found that antinociception levels increased by 85% [69%-102%] (mean, [95% Cl]) at the 10-minute time points of 1-hour stimulations in 18 experiments across 6 animals. Antinociception neither increased nor decreased significantly over the course of the stimulation. The levels of antinociception decayed back to baseline ranges within 26 [22-31] (mean, [95% Cl]) minutes after stimulation. Our findings suggest a promising step towards the design of behavioral states in general anesthesia by manipulating directly one of the brain's natural nociceptive pathways, in addition to or in place of the current pharmacology-based anesthesiology procedures.
by Shu Zheng.
M. Eng.
2
Sutthiwarotamakun, Rungrut. "Perpheral autoimmunity induces central neuro-inflammation and hippocampal neurogenesis impairment in a murine model of collagen induced Rheumatoid Arthritis". Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/3027/.
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Background: Psychiatric disorders are common in patients with autoimmune diseases such as rheumatoid arthritis. These disorders are poorly understood and are an important co-morbidity. They may occur as a consequence of the effects of the autoimmune inflammation on the central nervous system. Peripheral inflammation inducing central cytokine production in the CNS has been documented in acute inflammatory models such as after systemic LPS challenge, and cytokine administration has been shown to induce cognitive impairment and mood disorders. These disorders may be due to the central action of cytokines on neurogenesis and reduced hippocampal neurogenesis has been implicated in depression and cognitive decline. Peripheral inflammation and some specific cytokines have been reported to inhibit hippocampal neurogenesis, resulting in cognition impairment and depressive-like behaviour in animal models. Hypothesis: Based on this evidence, we hypothesized that peripheral inflammation associated with arthritis can induce central production of inflammatory mediators in the brain contributing to reduction in hippocampal neurogenesis thereby offering a mechanism and potential therapeutic targets for RA-associated psychiatric disorders. Aims and Methods: The aim of this project is 1) to investigate whether peripheral immune/inflammatory responses during arthritis can induce changes in inflammatory mediators in brains of collagen induced arthritis (CIA) mice, using this as a model for an adaptive immune response contributing to neurological disease development similar to the human disease. We used Luminex bead-based screening assays to determine a wide range of inflammatory mediator proteins in single small volume samples obtained from mouse brain tissues. In the same tissues, the transcription levels of genes encoding these inflammatory mediators were also quantified using real-time PCR and quantified as absolute copy numbers. 2) To investigate whether peripheral immune/inflammatory responses during arthritis can induce changes in hippocampal neurogenesis in brains of collagen induced arthritis (CIA) mice, we also measure changes in hippocampal neurogenesis in CII immunized mice using the immunohistochemistry of neuronal marker doublecortin (DCX). In order to confirm that changes in both inflammatory mediators and hippocampal 3 neurogenesis were due to peripheral inflammation, CII immunized mice were given peripheral anti TNF-α etanercept treatment. Inflammatory mediator profiles and hippocampal neurogenesis in brains of etanercept-treated CII immunized mice were compared to PBS -treated CII immunized mice and naive control mice. Results: Systemic etanercept treatment attenuated arthritis in CII immunized mice. IL-1β, IL-5, CXCL1 and FGF2 protein were increased in the serum of CII immunized mice. In addition, we found up-regulation of protein and gene concentrations of IL-1β, IL-1-α, TNF-α, IL-6, IFN-γ, IL-2, IL-12, IL-4, IL-5, CXCL1, CXCL0 and CCL2, VEGF and FGF2 in brains of CII immunized mice compared to those in naive control mice. The reduction in number of DCXpositive neurons in the dentate gurus of CII immunized mice compared to those in naive control mice, suggesting the impairment in hippocampus neurogenesis in CII immunized mice. In addition, reduction of inflammatory mediators, including IL-1β, TNF-α, IL-12, CXCL1, and increases of IL-6, IL-2 and VEGF and FGF2 protein concentrations were observed in brains of etanercept-treated CII immunized mice compared to those in untreated CII immunized mice. In addition, the impairment in hippocampal neurogenesis was reversed by peripheral etanercept treatment in CII immunized mice. In conclusion, the data of this thesis shows that peripheral inflammation during arthritis potentially induces production of inflammatory mediators in brains of CII immunized mice. Up-regulation of these inflammatory mediators in the brain may be associated with the impairment in hippocampal neurogenesis of CII immunized mice. In addition, peripheral etanercept treatment seems to have protective effect against peripheral-induced brain inflammation and the impairment in hippocampal neurogenesis in CII immunized mice. In summary, we demonstrated that peripheral inflammation resulting from arthritis may induce brain inflammation and contribute to the impairment of hippocampal neurogenesis. Systemic etanercept treatment not only attenuated joint inflammation, but also reduced brain inflammation and reversed the impairment in hippocampal neurogenesis resulting from peripheral inflammation in CII immunized mice.
3
Miedzinski, Rafal. "Etude des effets optiques photo-induits dans les métallo-composites et analyse de leurs caractéristiques surfaciques par microscopie à force atomique". Reims, 2009. http://theses.univ-reims.fr/sciences/2009REIMS038.pdf.
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La thèse présente analyse les phénomènes photo-induits optiques dans les métallo-composites avec l'utilisation du microscope à force atomique. Le sujet de l'analyse sont les ITO (indium tin oxide), FTO (fluorine tin oxide) et ZnO qui comportent des métallo-composites d'argent et d'or. Les dimensions de ces métallo-composites sont à peu près égales à 60-80 nm. Les couches d'ITO et FTO ont de très interessantes propriétés optiques et électriques. Avec ces matériels se construisent des diodes électro luminescentes organiques, des écrans à crsitaux liquides et des écrans plasma
4
Procino, I. "Laser induced molecular axis alignment : measurement and applications in attosecond science". Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1333960/.
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This thesis reports the measurement and applications of molecular axis alignment induced by strong non-resonant linearly polarised laser fields. The spatial alignment of gas phase molecules overcomes the loss of information that results from averaging angle-dependent quantities over all the possible orientations of an isotropic sample. Therefore, laser-induced molecular alignment techniques are an essential component in new experiments aimed at measuring the structure of molecules with attosecond time resolution. In the first part of this thesis an experiment to measure molecular axis alignment is described. This experiment is based on the velocity map imaging technique in conjunction with time-resolved femtosecond laser Coulomb explosion of the molecular sample by an intense circularly polarised laser beam. A circularly polarised beam is needed to ensure a uniform detection efficiency for each possible orientation of the molecular axis in the polarisation plane. However, such a polarisation produces ion distributions that are not cylindrically symmetric, preventing the use of the standard Abel inversion technique to retrieve the three-dimensional ion distributions from the detected two-dimensional images. A new inversion algorithm is presented that allows the retrieval of molecular axis distributions from angular distributions of ions without cylindrical symmetry. The second part of the thesis focuses on the application of laser-induced molecular alignment to retrieve molecular structure and dynamics from high-order harmonic generation (HHG) experiments. HHG with a mid-infrared laser source (1300 nm) from aligned molecular samples of CO2, N2, C2H2, and N2O are presented. The use of a laser source with a wavelength longer than that used in previous experiments (800 nm) has increased the amount of information obtainable from such experiments. These experiments have provided insight into the hole dynamics of CO2 following ionisation, and reveal for the first time structural features in the HHG spectra of molecules with low ionisation potentials such as C2H2.
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Tseng, Yu-Chou. "Application of Histone Deacetylase Inhibitor AR-42 in the Treatment of Cancer-induced Cachexia". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500375156831813.
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Mora, Gómez Luis Fernando. "Bifurcations dans des systèmes avec bruit : applications aux sciences sociales et à la physique". Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4228.
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La théorie des bifurcations est utilisée pour étudier certains aspects des systèmes dynamiques qui intervient lorsqu'un petit changement d'un paramètre physique produit un changement majeur dans l'organisation du système. Ces phénomènes ont lieu dans les systèmes physiques, chimiques, biologiques, écologiques, économiques et sociaux. Cette idée unificatrice a été appliquée pour modéliser et explorer à la fois tant les systèmes sociaux que les systèmes physiques. Dans la première partie de cette thèse, nous appliquons les outils de la physique statistique et de la théorie des bifurcations pour modéliser le problème des décisions binaires dans les sciences sociales. Nous avons mis au point un schéma permettant de prédire l’apparition de sauts extrêmes dans ces systèmes en se basant sur la notion de précurseurs, utilisés comme signal d'alerte d'apparition de ces événements catastrophiques. Nous avons également résolu un modèle mathématique d’effondrement social fondé sur une équation de "régression logistique" utilisée pour décrire la croissance d’une population et la façon dont celle-ci peut être influencée par des ressources limitées. Ce modèle présente des bifurcations sous-critiques et nous avons étudié sa relation avec le phénomène social du « sunk-cost effect » (effet de coût irrécupérable). Ce dernier phénomène explique l’influence des investissements passés sur les décisions présentes, et la combinaison de ces deux phénomènes est utilisé comme modèle pour expliquer la désintégration de certaines sociétés anciennes (basés sur des témoignages archéologiques). Dans la deuxième partie de cette thèse, nous étudions les systèmes macroscopiques décrits par des équations différentielles stochastiques multidimensionnelles ou, de manière équivalente, par les équations multidimensionnelles de Fokker-Planck. Afin de calculer la fonction de distribution de probabilité (PDF), nous avons introduit un nouveau schéma alternatif de calcul basé sur les intégrales de chemin (« Path Integral ») lié aux processus stochastiques. Les calculs basés sur les intégrales de chemin sont effectués sur des systèmes uni et bidimensionnels et successivement comparés avec certains modèles dont on connaît la solution pour confirmer la validité de notre méthode. Nous avons également étendu ce schéma pour estimer le temps d’activation moyen (« Mean Exit Time »), ce qui a donné lieu à une nouvelle expression de calcul pour les systèmes à dimension arbitraire. A` noter que pour le cas des systèmes dynamiques à deux dimensions, les calculs de la fonction de distribution de probabilité ainsi que du temps de sortie moyen ont validé le schéma des intégrales du chemin. Ça vaut la peine de souligner que la perspective de poursuivre cette ligne de recherche repose sur le fait que cette méthode est valable pour les « non gradient systems » assujettis à des bruits d'intensité arbitraires. Cela ouvre la possibilité d'analyser des situations plus complexes où, à l'heure actuelle, il n'existe aucune méthode permettant de calculer les PDFs et/ou les METsBifurcations in continuous dynamical systems, i.e., those described by ordinary differential equations, are found in a multitude of models such as those used to study phenomena related to physical, chemical, biological, ecological, economic and social systems. Using this concept as a unifying idea, in this thesis, we apply it to model and explore both Social as well as Physical systems. In the first part of this thesis we apply tools of statistical physics and bifurcation theory to model a problem of binary decision in Social Sciences. We find an scheme to predict the appearance of extreme jumps in these systems based on the notion of precursors which act as a kind of warning signal for the upcoming appearance of these catastrophic events. We also solve a mathematical model of social collapse based on a logistic re-growing equation used to model population grow and how limited resources change grow patterns. This model exhibits subcritical bifurcations and its relation to the social phenomenon of sunk-cost effect is studied. This last phenomenon explains how past investments affect current decisions and the combination of both phenomena is used as a model to explain the disintegration of some ancient societies, based on evidence from archeological records. In the second part of this thesis, we study macroscopic systems described by multidimensional stochastic differential equations or equivalently by their deterministic counterpart, the multidimensional FokkerPlanck equation. A new and alternative scheme of computation based on Path Integrals, related to stochastic processes is introduced in order to calculate the Probability Distribution Function. The computations based on this Path Integral scheme are performed on systems in one and two dimensions and contrasted to some soluble models completely validating this method. We also extended this scheme to the case of computation of Mean Exit Time, finding a new expression for each computation in systems in arbitrary dimensions. It is worth noting that in case of two-dimensional dynamical systems, the computations of both the probability distribution function as well as of the mean exit time validated the Path Integral scheme and the perspective for continuing this line of work are based on the fact that this method is valid for both arbitrary non gradient systems and noise intensities. This opens the possibility to explore new cases, for which no methods are known to obtain them
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Ito, Masahiro. "Search for supernova induced gravitational wave bursts with optimal filter technique on LIGO science data /". view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1188882241&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Thesis (Ph. D.)--University of Oregon, 2006.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 113-116). Also available for download via the World Wide Web; free to University of Oregon users.
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Garetto, Anthony Mr. "Electron Beam Induced Chemistry". NCSU, 2007. http://www.lib.ncsu.edu/theses/available/etd-03292007-064656/.
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The purpose of this research has been to investigate the mechanisms and develop techniques for electron beam induced chemistry. Applications for electron beam chemistry include repair and fabrication of lithographic masks, integrated circuit repair and rewiring, nanofabrication of functional nanoscale tools and scanned probe microscopy tips and damage free transmission electron microscope sample preparation. The use of hydrocarbon contamination as a precursor has been investigated and complex three dimensional nanostructures have been successfully fabricated. Accelerating voltage and scan speed can be used to control the morphology of the deposits. The development and implementation of an internal precursor reservoir and introduction device that is transferable to various scanning electron microscope and focused ion beam instruments has been performed. The effects of beam and scan parameters on the deposition efficiency of carbon structures utilizing a phenanthrene precursor has been investigated. Deposition efficiency is maximized for low beam current, large scan areas exposed for short times using the experimental conditions in this work. However, the use of a focused ion beam provides a significantly higher deposition efficiency (over 45 times) than that of an electron beam.
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Markines, Benjamin C. "Socially induced semantic networks and applications". [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:3358934.
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Thesis (Ph.D.)--Indiana University, Dept. of Computer Science, 2009.Title from PDF t.p. (viewed on Feb. 10, 2010). Source: Dissertation Abstracts International, Volume: 70-05, Section: B, page: 3003. Adviser: Filippo Menczer.
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Rogers, Stephen Christopher. "Delmopinol-induced matrix removal facilitates photodynamic therapy and chlorhexidine methods for disinfecting mixed oral biofilms". Thesis, State University of New York at Buffalo, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1561655.
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It is often observed that the slimy matrixes of various bacterial-formed biofilms can limit their disinfection. This investigation demonstrated that disinfection effectiveness by either photodynamic therapy (PDT) or chlorhexidine irrigation is significantly improved by collapse of that matrix using the non-bactericidal reagent delmopinol as part of the treatment sequence. Cyclic shear-producing conditions were used to grow 4-day, whole salivary and growth media biofilms on glow-discharge-treated polystyrene (N=46) and mini-germanium internal reflection prisms to serve in a periodontal crypt model of disinfection by either methylene-blue-mediated PDT or by chlorhexidine irrigation. Assays for bacterial viability, with and without treatments, were performed by alamarBlue® fluorescent methods, statistically applied (ANOVA, Tukey's HSD). Multiple Attenuated Internal Reflection Infrared (MAIR-IR) assays confirmed selective removal of the predominantly polysaccharide matrix materials by the delmopinol treatment, but not by equivalent water or chlorhexidine methods. Confocal-IR microscopy showed that the delmopinol reagent, alone, caused about one-third of each wet biofilm to be removed, while bacterial re-growth was confirmed by alamarBlue® assay. Chlorhexidine and PDT suppression of bacterial activity without regrowth was significantly improved with the added delmopinol treatment, and is likely to provide similarly beneficial results in the effective disinfection of diverse biofilms in many settings.
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Dubner, Andrew D. (Andrew David). "Mechanism of ion beam induced deposition". Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13637.
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Alhaddad, Aisha. "IRRADIATION OF HS578T BREAST TUMOR CELLS INDUCES NON-CYTOPROTECTIVE AUTOPHAGY". VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3437.
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Cancer is the second most common cause of death in the US. The most frequently observed cancer type in women is breast cancer. A special type of breast cancer is triple negative (TNBC) cancer that is characterized by lacking three receptors: estrogen, progesterone and human epithelial growth factor (HER 2). The HS578t breast cell line is a model of TNBC that also has a mutation of the p53 protein. Ionizing radiation is used widely in the clinic to debulk tumors before surgery as well as post-surgery to eliminate residual tumor cells outside the surgical field. Previous studies from our laboratory showed that inhibition of autophagy does sensitize p53 wild type MCF-7 and ZR-75 breast tumor cells to radiation. However, this is not necessarily the response in all breast cell lines. The Hs578t cells did not appear to be sensitized to radiation after inhibition of autophagy using chloroquine as a pharmacological inhibitor. The present study was designed to build upon these previous findings and further confirm that the Hs578t breast cell line could not be sensitized to radiation through autophagy inhibition. Time course studies showed a reduction of viable cell number upon irradiation of Hs578t breast tumor cells and that both autophagy and senescence were induced. Acridine orange staining was used to examine the acidic vacuole formation while β-galactosidase staining indicated the promotion of senescence. Flow cytometry was used to quantify both autophagy and senescence. Inhibition of autophagy using pharmacological inhibitors such as ammonium chloride, or genetic silencing of autophagy by beclin1, which is a protein initiator of autophagy, did not sensitize Hs578t breast tumor cells to irradiation. It shows from these studies that autophagy is not necessarily cytoprotective in all breast cancer cell lines, which should be considered in current clinical trials designed to sensitize tumor cells to chemotherapy and radiation through inhibition of autophagy.
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Chen, Wei. "Modelling of tumour-induced angiogenesis". Thesis, Northumbria University, 2015. http://nrl.northumbria.ac.uk/30235/.
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Controlled by extracellular signals, tumour-induced angiogenesis is a crucial step in the development of tumours. Among the many cell signals already identified, the VEGF and Notch signalling pathways play a critical role in controlling endothelial cells (ECs) during angiogenesis. Although this regulatory mechanism has become a current research focus in biology, its computational modelling is still rare. We focus on developing a computational model to simulate the VEGF and Notch signalling regulatory mechanism to perceive the micro procedure of angiogenesis in silico and fill the gap between biology and computer engineering. We first developed a mathematical model with nonlinear partial differential equations (PDEs) to describe the migration of endothelial tip cells during tumour-induced angiogenesis. The simulation results show that both chemotaxis and haptotaxis have impacts on the migration of ECs in velocity and density, and the impacts depend on the gradient and direction of tumour angiogenenic factor (TAF), and fibronectin, implying a possible malignant mechanism for some subgroups of tumour. We then developed the model further to simulate the regression, recurrence or clearance of tumours due to tumour cytotoxic factors, including the immune system and drugs delivered through the vessels formed during angiogenesis, providing a broader understanding of tumours. Based on the PDE model which provided parameters of continuum mathematical model, we finally developed an enzymatic catalysed regulating model in the form of ordinary differential equations (ODEs) with agent-based modelling (ABM) using Java and MATLAB languages, to visually realise the sprouting regulated by VEGF and Notch signalling during angiogenesis. The simulation describes the process of how an endothelial stalk cell becomes an endothelial tip cell, and sprouts under the influence of VEGF and Notch signalling, revealing the relationship between sprouting and branching. As the simulation results are consistent with reported in vitro and in vivo assays, the study bridges angiogenesis research and computer modelling from the dynamic regulatory mechanism perspective, offering a huge leap over previous studies in computationally simulating tumour-induced angiogenesis. It is hoped that the results will assist researchers in both the experimental and theoretical angiogenesis communities to improve understanding of the complexity and identify the fundamental principles of angiogenesis, whilst also using modelling approaches that will enrich knowledge for computational scientists in this field.
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Mobley, James Austin. "Oxidative mechanisms of estrogen induced carcinogenesis /". The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu148819623490807.
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Gall, Lewis Simpson. "Trauma-induced coagulopathy : an investigation of fibrinolysis and the effect of tranexamic acid". Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/44690.
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Haemorrhage is a leading cause of trauma morbidity and mortality, with many deaths potentially preventable. Hyperfibrinolysis is a central characteristic of trauma-induced coagulopathy (TIC) which develops rapidly and is associated with poor outcomes. Tranexamic acid (TXA) improves survival in trauma haemorrhage but its uptake worldwide remains variable, in part because its effects on the coagulation system during trauma haemorrhage have not been described. Further uncertainty regarding patient selection for TXA therapy has emerged following the description of an early viscoelastic haemostatic assay (VHA) diagnosed hypofibrinolytic phenotype in whom TXA may potentiate thrombotic complications. The patient characteristics and mechanisms leading to this apparent hypofibrinolytic phenotype are poorly understood. Over 900 trauma patients prospectively recruited to a multicentre observational cohort study had blood drawn within 2-hours of injury for VHA and fibrinolysis plasma protein analysis. Patients were categorised according to VHA maximum lysis (ML) and D-dimer (DD) levels. Patients with MLLOW exhibited heterogeneity in clinical and injury characteristics and outcomes. Those who died were severely injured, with a high incidence of traumatic brain injury and a 7-fold higher D-dimer. Patients with MLLOW+DDHIGH had a hyperfibrinolytic biomarker profile, with the fibrinolytic mediator S100A10 identified as a potential driver of fibrinolysis, which can ex-vivo artificially reduce ML. Empiric TXA could benefit this occult hyperfibrinolytic phenotype. Over two subsequent observational studies, the effects of TXA on the coagulation system during trauma haemorrhage and the effect of TXA infusion and timing of treatment on thrombotic events were investigated. Early empiric TXA avoided VHA-hyperfibrinolysis and provided a degree of protection from TIC. Whilst univariate analysis suggested increased thromboses with later TXA treatment in patients receiving TXA bolus+infusion, neither the TXA infusion nor time to bolus were associated with thrombotic events after multivariate analysis. A single TXA bolus may provide a lower effective therapeutic dose with reduced complications.
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Della, Ratta Anthony D. (Anthony David). "Focused ion beam induced deposition of copper". Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12418.
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Kofinas, Peter. "Shear induced morphology of semicrystalline block copolymers". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/28087.
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Đjurdjević, Predrag (Predrag Dragutin). "Molecular dynamics modeling of orientation-induced nucleation in short alkanes : toward molecular modeling of flow-induced crystallization in polymers". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79557.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2013.Title as it appears in MIT degrees awarded booklet, September 2012: Molecular simulation of primary nucleation and growth from oriented melts in polyethylene. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 59-63).
The enhancement of the primary flow-induced nucleation rate in short chain alkanes (C20 and C150) has been examined for different levels of orientation by atomistic molecular dynamics simulations. The nucleation rate has been found to change drastically by varying average molecular orientation and temperature. For example, it is possible to accelerate nucleation kinetics by three orders of magnitude at the same temperature, but varying the average level of orientation (P2 (cos [Theta])) . The size of the critical nucleus has been found to increase with the level of undercooling Tm - T decrease, consistent with the classical nucleation theory. Our atomnistic molecular dynamics simulation model is even tractable at the small levels of undercooling, thus clearly demonstrating the effects of orientation (melt anisotropy) on nucleation kinetics when thermal nucleation is expected to be negligible. Furthermore, we calculate the influence of melt anisotropy on the growth rate. As expected, the growth rate is also altered by melt anisotropy. Furthermore, the growth rate maximum always occurs at the temperature above the nucleation kinetics maximum.
by Predrag Đjurdjević.
S.M.
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Müller, Jan Ole [Verfasser] y C. [Akademischer Betreuer] Barner-Kowollik. "Development and Application of Modular Light-Induced Ligation Techniques in Polymer Science / Jan Ole Müller. Betreuer: C. Barner-Kowollik". Karlsruhe : KIT-Bibliothek, 2015. http://d-nb.info/1075253721/34.
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Li, Yan Julia. "Cisplatin-induced cytotoxicity in MDCK cells". Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6408.
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Background. The mechanism of cisplatin-induced nephrotoxicity is not well understood. The distal tubules are affected in both human and animal studies, although the majority of cisplatin-induced renal damage is in proximal tubules. Platinum (Pt) forms intra- and interstrand cross-links with DNA in cancer cells. Hypothesis. A mechanism of cisplatin-induced cytotoxicity in MDCK cells relates to its ability to bind to DNA and interfere with its synthesis. Methods. The canine distal renal tubular epithelial cell line, MDCK was used as an in vitro model to investigate the mechanism of cisplatin-induced nephrotoxicity. The intracellular Pt accumulation and Pt binding with DNA were assayed by atomic absorption spectrophotometry. DNA synthesis was measured by BrdU labeling and fluorescence microscopy at the concentrations from 0 to 100 muM. The alkaline comet assay with 10 Gy radiation was used to measure Pt DNA interstrand cross-links after a one hour cisplatin exposure from 0 to 100 muM at both zero and sixteen hour time points. According to the principles of alkaline comet assay, the tail moment is inversely related with the amount of Pt interstrand cross-links. (Abstract shortened by UMI.)
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Wall, Johanna Martine. "Trauma-induced secondary cardiac injury". Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/43998.
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Trauma-induced secondary cardiac injury (TISCI) represents an under recognised complication of severe injury with haemorrhage. A limited number of clinical studies have supported the development of adverse cardiac events, such as arrhythmia, in association with biomarker proven TISCI. Pre-clinical studies using small animal models have provided insights into potential mechanisms and key effector molecules involved in the development of TISCI, but there remains a general lack of understanding regarding the in vivo functional implications of this indirect cardiac injury resulting from trauma-haemorrhage. This project aimed to investigate the implications of cardiac injury on myocardial systolic function. A robust, translatable model of TISCI was developed, which reflected the cardiac biomarker profile identified in clinical studies and, for the first time, demonstrated a significant, dose-dependent rise in Heart-type Fatty Acid Binding Protein (H-FABP) in response to trauma-haemorrhage. Non-invasive echocardiography was used to determine the acute myocardial response to injury and haemorrhage and also to assess the response of the left ventricle to resuscitation after an antecedent 60-minute period of trauma-haemorrhage. The functional studies presented here have enabled real time visualisation of the impact of trauma-haemorrhage upon systolic left ventricular function over 1 to 6 hours, both with and without resuscitation. Having established the trends in in vivo systolic function over time, further studies were then conducted to test the combination of adenosine, lidocaine and magnesium (ALM) as a cardiovascular rescue agent in TISCI. ALM, as an adjunct to fluid resuscitation, has shown great promise as a therapeutic agent which improves haemodynamic outcomes, reduces the volume of resuscitation fluid required and favours survival in the murine model of TISCI.
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Alvarez, Blanco Pedro. "High-pressure induced gelation of globular proteins". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32348.
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This thesis is focused on the structural and rheological changes in globular proteins when subjected to high pressure processing (HPP), a novel non-thermal food processing technique. Structure-functionality changes associated with thermal processing has been well studied, but little is known for HPP. One of the principal objectives of this thesis was to compare protein structure-functionality relationship between thermal and HP processing. Three groups of proteins of varying complexity and source were studied: beta-lactoglobulin (b-lg), a small well understood protein from cow's milk whey (model system); porcine blood plasma proteins, and soy protein concentrate. Blood is generally considered a waste from the meat industry, plasma is obtained from centrifugation of the blood and is composed mainly of serum albumin and globulins (simplified multi-component system). Soy protein concentrate (SPC) is a complex system of vegetable proteins composed of a varied mix of large glycoproteins. In general, HPP affected protein structure and functionality, but the specific effects depended on the protein characteristics. Pressure-independent parameters, like concentration and pH, exerted a major influence on protein denaturation and influenced the HP-induced gel network formation. For b-lg, significant structural changes were observed at 600 MPa and these correlated to changes in the viscoelastic properties. HP-induced gelation did not follow the classic structural changes observed on thermal gelation. Protein gels of comparable strength were produced by thermal and HPP (conc. ≥ 20 %); the heat induced gels were stiffer than their HP-induced counterparts, the latter only modestlyCette thèse est concentrée sur les changements structuraux et rhéologiques des protéines globulaires une fois soumise à l'haute pression procès (HPP), une technique non thermique innovatrice de traitement des produits alimentaires. Il y a un ensemble de connaissances impressionnant sur les changements de structure-fonctionnalité liés au procès thermique mais peu est connu pour HPP. Un des principaux objectifs de cette thèse était de comparer le rapport de structure-fonctionnalité entre les deux procédés (haute pression et thermique). Trois groupes de protéines on été étudiés en variant la complexité et la provenance : la β-lactoglobuline, une petite protéine très bien connu, provenant du lait de vache (système modèle); les protéines de plasma sanguin porcine, et le concentré protéique de soja (SPC). Le sang est généralement considéré comme un dechet de l'industrie de viande, le plasma est obtenu à partir de la centrifugation du sang et se compose principalement d'albumine sérique et de globulines (système simplifié à plusieurs éléments). Le concentré protéique de soja est un système complexe des protéines végétales composées de mélange divers de grosses glycoprotéines. Généralement le traitement de HP a affecté la structure et la fonctionnalité de protéine, mais les effets spécifiques de HP sur les protéines ont dépendu des caractéristiques du système en question. Les paramètres comme la concentration en protéine et le pH, ont exercé une influence importante sur la dénaturation des protéines et ainsi que la formation de gels. Un vrai gel a été formé seulement après application de 650 MPa et une concentr
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Nilsson, Martin. "Water-Induced Charge Transport in Microcrystalline Cellulose". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6815.
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Washabaugh, Andrew Patrick. "Flow induced electrification of liquid insulated systems". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11839.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (leaves 381-391).
by Andrew Patrick Washabaugh.
Sc.D.
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Loening, Andreas Markus 1975. "Injurious compression induced apoptosis in articular cartliage". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80608.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 113-121).
by Andreas Markus Loening.
M.Eng.
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Hsu, Stephen Charles. "Motion-induced degradations of temporally sampled images". Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/49571.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Bibliography: leaves 155-160.
by Stephen Charles Hsu.
M.S.
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Karmacharya, Rabi. "Audiogravic illusion induced by acceleratory force fields". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43513.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.Includes bibliographical references (leaf 50).
by Rabi Karmacharya.
M.Eng.
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Clas, David. "Nifedipine inhibits cholecystokinin induced gallbladder contraction". Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60499.
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The purpose of this study was to show that nifedipine, a calcium channel blocker, can decrease gallbladder contractility in guinea pigs and in man. Gallbladder contraction was measured in response to repeated injections of cholecystokinin both before and after the injection of nifedipine in three groups of five animals each. The mean amplitude of gallbladder contraction in response to cholecystokinin was decreased by 45, 73 and 67% (p $<$ 0.01) in response to intravenous nifedipine doses of 100, 200 and 300 $ mu$g respectively. In nine healthy human volunteers, gallbladder emptying was measured by radionuclide cholescintigraphy in response to cholecystokinin infusion before and after a 10 mg oral dose of nifedipine. Gallbladder ejection fraction was significantly decreased by 29% (p $<$ 0.001). These data demonstrate that nifedipine is a potent inhibitor of gallbladder contractility.
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Chen, Ye. "Induced regulatory T cells in transplantation tolerance". Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:cffc275b-d32c-495e-a1da-55421a57e7e7.
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Induced regulatory T cells (iTreg) play an important role in the induction of tolerance to self and non-self antigens. Harnessing their suppressive potential has therapeutic implications for the treatment of autoimmune conditions and transplant rejection. Although the role of TGFβ-conditioned iTreg in natural and therapeutic tolerance is indisputable, their mechanism of action as well as factors that influence their function and stability in vivo remain unclear. Here it is shown that TGFβ-conditioning of T cells in the absence of any Foxp3 expression is insufficient for conferring a suppressive phenotype in vivo, whilst Foxp3 expression is sufficient to enable naïve T cells to become suppressive both in vitro and in vivo. Graft antigen was found to enhance the number of iTreg-derived Foxp3+ cells localising to the draining lymph nodes of recipients, and this was associated with histone modifications at the Foxp3 locus that suggested a stabilisation or 'affirmation' of Foxp3 expression. Finally, iTreg were shown to 'out-compete' naïve T cells in forming clusters with dendritic cells. Activated inflammatory T cells could also 'out-compete' naïve T cells. However, unlike activated T cells, iTreg did not activate interacting DCs to the same extent, and this may potentially be a mechanism of their action in vivo.
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Christodoulopoulos, Pota. "Monocyte chemotactic proteins in allergen-induced rhinitis". Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21526.
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Allergen-induced rhinitis is associated with the recruitment and activation of inflammatory cells, particularly eosinophils and CD4 + T cells into the nasal mucosa. Monocyte chemotactic proteins (MCPs) have been shown to induce chemotactic activity in these particular cell types under in vitro assay conditions. To assess the contribution of MCPs in the recruitment of inflammatory cells in vivo, we investigated the allergen-induced late response in subjects with allergic rhinitis. Using immunocytochemistry and in situ hybridization, we demonstrated a constitutive expression of MCP-1, -3 and -4, of which MCP-3 and -4 were significantly increased in the nasal mucosa following allergen provocation. This upregulation of MCP-3 and 4 immunoreactivity in response to allergen, was reduced in patients pretreated with topical corticosteroids. Colocalization experiments revealed that the majority of MCP-positive cells were macrophages. The results of this study suggest that allergen-induced rhinitis is associated with an increased expression of MCP-3 and -4, which may be closely related to the influx of inflammatory cells and may thus contribute to the pathogenesis of allergic rhinitis.
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Hong, Fei. "ANALYSIS OF ELECTROPHILE-INDUCED NRF2 GENE ACTIVATION". Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1280%5F1%5Fm.pdf&type=application/pdf.
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Pacella, James N. "Field induced switching in multilayer rhombic magnetic rings". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/44814.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007."June 2008."
Includes bibliographical references (leaf 28).
Multilayer rhombic magnetic rings are researched as a structure for the "pseudo spin valve" device that could possibly become useful in magnetic materials applications such as MRAM, digital logic, and sensors through the use of multiple resistance states exhibited within these devices. The magnetization reversal characteristics of these structures are explored in an effort to fully understand interactions occurring within the devices and their resulting effect on giant magnetoresistance (GMR). Contact configuration and angular dependence of applied field are also examined. Using submicron thickness rhombic rings with long axis dimension -1.5gjm, major loop magnetization sweeps were conducted, as well as minor loops in order to excite several resistance states within the devices. It was found from major loop applied field sweeps that rhombic multilayer rings exhibit five stable magnetoresistive states, with an additional state excited through execution of a minor loop field sweep. In addition, using the contact configurations known as "classical" and "wheatstone bridge" provide additional information on interactions that are occurring within the structures. It was found that both contact configurations were sensitive to similar changes in the devices, however, through different means of sensing. The major difference results in a larger GMR output in the wheatstone bridge configuration (-20%) versus the classical configuration (-1%). Preliminary work in angular dependence has shown the ability to alter resistance plateaus by changing the angle of applied field. Ultimately shown through this work is the amount of research that is still needed to truly understand these devices, as they contain more complex stable and metastable states of magnetization than generations and shapes before them.
by James N. Pacella.
S.B.
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Badger, Andrew Ashley 1970. "Alterations in chemically-induced liver injury by immunomodulators". Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282642.
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Studies presented in this dissertation determined biochemical mechanisms underlying the modulation of chemical-induced liver injury by retinol and GdC₃ The first objective was to determine the role of inflammatory cells in the retinol potentiation of CCl₄-induced liver injury. Plasma alanine aminotranferase activities and histological analysis of liver sections both illustrated significant potentiation of CCl₄ hepatotoxicity by a single dose of retinol. The mechanism for this potentiation involves priming of Kupffer cells (KC) (i.e. by enhancing their response to toxic stimuli) as established by chemical inhibitors of KC, isolated KC, and immunohistochemical analysis of liver sections. Additional studies estimated the effect of retinol on non-inflammatory processes (i.e. cytochrome P450 (P450) activity). While total P450 content was not increased, the activity and concentration of CYP 2E1 were both significantly elevated following treatment with a single dose of retinol. These findings suggest that a single pretreatment with retinol potentiates CCl₄ hepatotoxicity by multiple mechanisms that involve increased biotransformation and inflammatory cell activities. Based on the findings with retinol, another immunomodulating agent, GdCl₃ might also alter the activity of hepatic biotransforming enzymes. Having established that GdCl₃ inhibits the activity of KC, the purpose of these studies was to determine the effect of GdCl₃ on the content and activity of hepatic P450. GdCl₃ treatment reduced total hepatic microsomal P450 as well as aniline hydroxylase activity by 30% in male and 20% in female rats. Hepatocytes isolated from rats pretreated with GdCl₃ were less susceptible to toxicity caused by CCl₄ but not cadmium, a hepatotoxic chemical not bioactivated by P450. Thus GdCl₃-mediated protection from toxicity in vivo might involve decreased biotransformation and inflammatory cell activities. Data presented in this dissertation suggest that, in addition to altering the inflammatory response to toxicants, retinol and GdCl₃ may modulate liver injury by altering the P450-mediated bioactivation of chemicals. Considering the multiple effects described here for each of these compounds, investigators should be cautious in the interpretation of data utilizing retinol or GdCl₃ to implicate KC as the sole contributor to toxicological mechanisms. This is especially important in models of chemical-induced injury in which bioactivation is a key feature.
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Beischel, Julie M. "Retrovirally induced dilated cardiomyopathy in murine acquired immunodeficiency syndrome". Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280256.
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Acquired immunodeficiency syndrome (AIDS) has been associated with several cardiovascular abnormalities including dilated cardiomyopathy (DCM). DCM is characterized by dilation of the left ventricle and abnormal systolic and diastolic left ventricular function and is often associated with myocarditis and alterations in the extracellular matrix. The prevalence and severity of AIDS-associated DCM necessitates a better understanding of its disease process. To study AIDS DCM, the LP-BM5 murine AIDS (MAIDS) model, which offers many similarities to AIDS and several advantages as a model, was used. The cardiac function of MAIDS mice was compared to control mice using a conductance catheter system and left ventricular dimensions and compliance were significantly altered indicating a dilated cardiomyopathy. Competitive polymerase chain reaction was used to quantify the LP-BM5 retrovirus in splenic and cardiac tissue from MAIDS mice and illustrated active viral replication in spleen as well as heart tissue during the disease process. Immunohistochemistry and Northern blot analysis were used to determine the role of inflammation in this process: No staining was observed for immune cell infiltrates or the inflammatory mediators tumor necrosis factor-alpha and inducible nitric oxide synthase. The content of cardiac collagen, the major determinant of ventricular architecture, was significantly decreased in MAIDS mice compared to controls and LP-BM5 was shown to infect cardiac fibroblasts in vitro. Pharmacological treatment with zidovudine and/or indinavir prevented cardiac dysfunction through decreases in viral load without functional cardiotoxicity.
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Ocvirk, Rok. "Quantifying formalin-induced behaviours and morphine analgesia". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0016/MQ55083.pdf.
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Anderson, Steven P. "Gene modulation during peroxisome proliferator-induced hepatocarcinogenesis". NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20011101-131940.
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ANDERSON, STEVEN PAUL. Gene modulation in peroxisome proliferator-induced hepatocarcinogenesis. (Under the direction of Russell C. Cattley and John M. Cullen). Recognition that peroxisome proliferator chemicals are potent hepatic mitogens and carcinogens in rats and mice has generated concern about possible human health risks associated with exposure to several of these chemicals, many of which have medical or commercial utility. Our broad objective was to improve the estimation of human health risk following peroxisome proliferator exposure by defining a subset of the molecular events associated with the rodent tumors. Our working hypothesis was that peroxisome proliferator-induced tumors in rodents result from specific, peroxisome proliferator-activated receptor-a(Ppara)-modulated changes in gene expression. The research was directed toward three specific aims. First, we sought to identify genes associated with hepatocarcinogenesis induced by the peroxisome proliferator, Wy-14, 643, in the rat. The principle conclusion of these studies - that peroxisome proliferators dysregulate expression of hepatic acute-phase protein genes - suggested possible perturbations in cytokine signaling networks that also regulate cell growth. Second, although Ppara is necessary for the rodent hepatocarcinogenesis induced by peroxisome proliferators, we were interested in identifying more proximate mediators of the increased cell proliferation. Thus, we examined cytokine signaling in mice treated with peroxisome proliferators. We found that peroxisome proliferator-induced increases in cell proliferation is not mediated via Tnfasignaling, but instead may be mediated through interleukin-1b or interleukin-6. Third, because Ppara is necessary for the cell proliferation that follows peroxisome proliferator exposure, we hypothesized that the receptor may play a role in hepatocellular proliferation induced by other stimuli. Following partial hepatectomy, liver regeneration in Ppara-null mice is transiently impaired, and may result from altered expression of genes regulating the G1/S cell cycle checkpoint in hepatocytes from these mice. Overall, our studies suggest that hepatic Ppara activation (1) alters inflammatory mediators, (2) modulates several potentially mitogenic cytokines, and (3) is necessary for normal liver regeneration after partial hepatectomy. Our data, compared with data from similar experiments on human hepatocytes, may provide further clues about the differences and similarities between peroxisome proliferator exposure in humans and laboratory animals.
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Zheng, Zhi-Ying 1957. "Bile acid-induced DNA damage in bacteria". Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/291421.
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Bile acids have been implicated by epidemiologic evidence as causative agents in colon cancer. Previous studies have indicated that the bile acids damage DNA. However, the conjugated forms of bile acids (eg. tauro conjugates) have not been tested for interaction with DNA. The present study compared the DNA-damaging ability of unconjugated and conjugated bile acids using the E. coli SOS test system. The E. coli tester strain was incubated with the bile acids and conjugated bile acids. Both cell survival and induction of the SOS response was measured. Among unconjugated bile acids, deoxycholate, chenodeoxycholate, and lithocholic acid were confirmed as DNA damaging agents by a decrease in surviving fraction and increase of the fraction of blue colonies undergoing SOS induction with increasing doses. Cholate, however, did not cause DNA damage by these criteria. Among the conjugated bile acids, taurochenodeoxycholate caused as much DNA damage as chenodeoxycholate. Taurodeoxycholate caused DNA damage, but had less of an effect than deoxycholate. Taurocholate and taurolithocholate failed to show a DNA damaging effect.
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Sainoki, Atsushi. "Dynamic modelling of mining-induced fault-slip". Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123291.
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In deep hard rock mines where high stress conditions take place, rockbursts are serious problems because rockbursts could result in severe damage to mine openings. It is widely recognized that mining activities could reactivate faults in underground mines. The reactivation of faults could then cause fault-slip. More importantly, fault-slip gives rise to seismic waves, which inflict severe damage to mine openings. Because the generation and propagation of seismic waves are dynamic phenomena, fault-slip needs to be also dealt with as a dynamic phenomenon. Both of the static and dynamic behaviour of faults should be examined, considering the effects of mining activities on the faults, in order to estimate the damage induced by the seismic waves First, a literature review is conducted. The review has revealed that although a number of dynamic and static friction laws have been proposed, the friction laws have been rarely employed for the simulation of fault-slip in underground mines. The review has also revealed that most of the simulations have been conducted in static conditions. In this thesis, dynamic modelling of mining-induced fault-slip is presented using a mine-wide model encompassing a fault. Furthermore, a case study of Garson Mine, Sudbury, Canada is carried out. A parametrical study with a mine-wide 3D model has led to the following conclusions: (a) mining depth, friction angle of the fault, and fault locations exert a large influence on the maximum relative shear displacements on the fault, while the dilation angle and stiffness of the fault do not, (b) maximum slip rates appear to increase with the maximum slip. Results obtained from the numerical analysis employing Barton's shear strength model have shown that fault surface roughness strongly affects the intensity of seismic waves and seismically radiated energy. The results imply that fault-slip occurring on faults with rough surfaces could become more violent. The effect of stope production blasts on a nearby fault is also examined. The results obtained from the analysis have indicated that performing stope production blasts in timed sequence could induce a larger seismic event on the fault than triggering the blasts simultaneously. Dynamic analysis considering the collision and unloading of fault surface asperities is also conducted. It is found that the release of normal stress due to fault unloading has a large influence on the intensity of seismic waves. The effect of slip-weakening distance on seismic source parameters of fault-slip is also investigated. The study has indicated that slip rates and seismically radiated energy are significantly affected by the slip-weakening distance, while seismic moment appears not to be susceptible to the slip-weakening distance in a case of local fault-slip.Back analysis of fault-slip to estimate the physical and mechanical properties of shear/fracture zones is carried out for Garson Mine. The back analysis is conducted with respect to moment magnitude and peak particle velocities recorded by seismic monitoring systems. Fault surface roughness and a dynamic friction angle have been calibrated. Afterwards, the calibrated values are validated with peak ground acceleration. Through the study, a methodology to calibrate the physical and mechanical properties of faults by means of ground motion due to seismic waves arising from fault-slip as well as seismic source parameters of the fault-slip has been developed.Dans les mines profondes ou des contraintes élevées se produisent, les coups de terrain sont un problème car les ils peuvent endommager les ouvertures minières. Il est largement reconnu que les activités minières peuvent réactiver des failles dans les mines sous-terraines. La réactivation de ces failles peut entrainer un glissement de faille. Surtout, le glissement de faille fait naitre des ondes sismiques qui infligent des dégâts sérieux quand elles frappent la surface des ouvertures minières. La génération et la propagation des ondes sismiques sont des phénomènes dynamiques. Il s'ensuit donc que le glissement de faille doit être traité comme un phénomène dynamique Le comportement dynamique ainsi que le comportement statique des failles doit être examiné en considérant les effets des activités minières pour estimer les dégâts causés par les ondes sismiques.Premièrement, un examen de la documentation est effectué. L'examen a révélé que même si un nombre de lois statiques et dynamiques de frottement ont été proposés, ces lois de frottement ont été peu employés pour simuler les glissements de faille que se déroulent dans les mines sous-terraines. La revue a aussi révélé que la majorité des simulations ont été conduites en conditions statiques. Dans cette thèse, la modélisation dynamique d'un glissement de faille induit par des activités minières est présentée. Le modèle englobe l'entièreté d'une mine. En plus, une étude de cas pour la mine Garson à Sudbury, au Canada, est effectuée.Une étude paramétrique avec un modèle de mine en trois dimensions mène aux conclusions suivantes: (a) la profondeur d'exploitation minière, l'angle de friction de la faille, et la position de la faille ont une grande influence sur les déplacement relatifs en cisaillement d'une faille, tandis que l'angle de dilation de la faille et la dureté ont peu d'effet, (b) le taux de glissement maximal augmente en fonction du glissement absolu. Les résultats obtenus du modèle numérique dans lequel le modèle de résistance au cisaillement de Barton est implémenté ont démontré que la rugosité de la surface de la faille affecte grandement l'intensité des ondes sismiques qui émanent du glissement de faille et l'énergie sismique propagée. Les résultats impliquent qu'un glissement de faille survenant à une faille rugueuse est plus violent. L'effet produit par un sautage de production sur une faille proche est aussi examiné en considérant plusieurs séquences de sautage. Les résultats de l'analyse indiquent qu'un sautage de production exécuté selon une séquence temporelle peut induire un plus grand événement sismique qu'un sautage simultané. Une analyse dynamique tenant compte la collision et le déchargement d'une faille est aussi conduite. Il est démontré que le relâchement de la contrainte normale à la faille a une grande influence sur l'intensité des ondes sismiques. L'effet de la distance d'affaiblissement de faille due glissement sur les paramètres sismiques est aussi examiné L'étude indique que le taux de glissement et l'énergie sismique émanée sont significativement affectés par la distance d'affaiblissement de faille, tandis que le moment sismique n'est pas susceptible à la distance d'affaiblissement dans le cas ou le glissement de faille se déroule seulement dans une zone limitée. Pour estimer l'effet des propriétés physiques et mécaniques de la zone de cisaillement, une analyse régressive est exécutée pour la mine Garson. L'analyse est conduite selon la magnitude du moment et la vitesse de crête des particules. La rugosité de la surface de la faille et l'angle de friction dynamique sont étalonnés. Ensuite, les paramètres étalonnés sont validés par rapport à l'accélération maximale du terrain. À travers l'étude, une méthodologie pour étalonner les propriétés physiques et mécaniques de la faille selon l'étude du mouvement du terrain due aux ondes sismiques émanant d'un glissement de faille est développé.
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Stanton, Catherine. "Proteolysis-induced changes in meat collagen during conditioning". Thesis, Bournemouth University, 1988. http://eprints.bournemouth.ac.uk/298/.
Texto completoResumen
Changes in intramuscular connective tissue brought about by conditioning were investigated in bovine muscles of different quality. Perimysial and endomysial collagens were solubilized to a small extent during conditioning and residual insoluble collagens in both connective tissue domains were damaged by proteolytic processing. Yields of soluble perimysial material from unconditioned muscles were significantly lower (p = 0.096) than from conditioned muscles. Solubilized perimysial collagen from unconditioned muscles was significantly lower (p = 0.015) than from conditioned muscles with 1±0.8 % of original collagen solubilized for unconditioned muscles and 3.4 ± 3.3 % for conditioned muscles. 87.5 % of the muscles examined showed an increase in percentage solubilized collagen due to conditioning. The main peptide components observed on analysis of insoluble perimysial fractions after CNBr digestion were derived from types I and III collagen. No changes were observed in the major peptide bands due to conditioning. Yields of soluble endomysial fractions representedo, n average,9 4.5 % of total extracted endomysial material for unconditioned muscles compared with 97.5 % for conditioned muscles. Soluble endomysial fractions contained, on average, 0.13 % collagen from unconditioned muscles and 0.22 % collagen from conditioned muscles. The main peptide components observed on analysis of insoluble endomysial fractions after CNBr-digestion were derived from types I and III collagen. Changes observed on the peptide maps, evident as the appearanceo f a number of new bandsf rom conditioned samples,a ppearedt o be muscle specific. % Type III collagen decreased on conditioning, indicating that endomysial type III collagen was preferentially destroyed during - conditioning. In model systems, insoluble perimysium treated with pepsin over 24 h resulted in little damage to the insoluble collagenous residue remaining. Insoluble perimysium treated with cathepsin resulted in changes to the major peptide bands on one-dimensional SDSpolyacrylamide gel electrophoresisw hich were evident after 24 h treatment. Two-dimensional peptide maps obtained from conditioned insoluble perimysium and from insoluble perimysium treated with cathepsin for 24 h were altered relative to the unconditioned insoluble perimysium, indicating proteolytic damage to high molecular weight fractions. The in vitro case was extreme, but was comparable with conditioned insoluble perimysium. In addition, new peptide material in conditioned perimysium and endomysium in the molecular weight range 40 000 to 50 000 was observed, while perimysial samples revealed loss of peptide material, due to conditioning. Percentage solubilized collagen was higher (p < 0.05) from three muscles of varying quality when pre-injected with 0.1 M lactic acid and conditioned from 1 to 14 days than from untreated muscles. Analysis of the high molecular weight collagen peptides from lactic acid treated muscles by two-dimensional SDS-polyacrylamide gel electrophoresis revealed increased incidence of degradation in this region compared with untreated controls. Sensory profiling using quality descriptive analysis (QDA) was carried out on three muscles of varying quality, pre-injected with 0.1 M lactic acid and results compared with untreated muscles. The results obtained failed to correlate the observed biochemical changes due to lactic acid treatment with perceived textural changes in these muscles. However, variability of the taste panel scores contributed significantly to the results obtained.
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Mertens, Samuel D. (Samuel David) 1975. "The hydrogen-induced piezoelectric effect in InP HEMTs". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/87453.
Texto completoResumen
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (p. 117-125).
Hydrogen exposure of III-V HEMTs has been shown to cause a threshold voltage shift, [delta] V[sub]T. This is a serious reliability concern. This effect has been attributed to a H-induced piezoelectric effect. Formation of TiH[sub]x expands the Ti layer in the gate, causing mechanical stress in the underlying semiconductor. This induces piezoelectric charge in the heterostructure underneath the gate that shifts the threshold voltage. This thesis investigates the influence of the gate and heterostructure dimensions and composition on the H-induced [delta] V[sub]T in order to come up with practical device level solutions to this problem. Towards this goal, a model for the impact of the hydrogen-induced piezoelectric effect on the threshold voltage of InP HEMTs was developed using 2D finite element simulations to calculate the mechanical stress caused by a Ti-containing gate that has expanded due to hydrogen absorption. A simple electrostatics model was used to calculate the impact of this piezoelectric polarization charge on the threshold voltage. This model explained the experimentally observed gate length dependence of AVT in InP HEMTs. Then, this model was experimentally verified using advanced InP HEMTs with a WSiN/Ti/Pt/Au gate or a thick Ti-layer in the Ti/Pt/Au gate stack. We have found that only a thin top layer of the thick Ti layer expanded after exposure to hydrogen. The impact of hydrogen on the threshold voltage of these devices is one order of magnitude smaller than conventional Ti/Pt/Au-gate HEMTs. The model showed that there are two main causes for the improvement of the H-sensitivity.
First, the separation of the Ti-layer from the semiconductor by a thick non-expanding layer significantly reduces the stress in the active layer. Additionally, the thinner heterostructure and the presence of an InP etch-stop layer with a small piezoelectric constant underneath the gate reduces the amount of threshold voltage shift that is caused by the mechanical stress. This thesis concludes that the H-induced piezoelectric [delta] V[sub]T can be significantly reduced by placing a non-expanding layer underneath the Ti-layer in the gate stack. Thinning the channel and insulator also helps mitigate the H-induced [delta] V[sub]T.
by Samuel D. Mertens.
Ph.D.
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Watts, Michael Robert 1974. "Wavelength switching and routing through evanescently induced absorption". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86858.
Texto completoResumen
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (p. 145-147).
by Michael Robert Watts.
S.M.
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Peleva, Emilia. "Comprehensive assessment of platinum-induced ototoxicity". Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107744.
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The chemotherapeutic agents cisplatin and carboplatin are widely-used and highly-effective against a variety of malignancies. Unfortunately, these medications may sometimes cause ototoxicity. Cisplatin and carboplatin ototoxicity manifests as tinnitus and/or a permanent, bilateral and progressive hearing loss, leading to devastating consequences on the lives of cancer survivors. Earlier detection of ototoxicity during treatment allows clinicians to modify treatment plans, whenever possible, to prevent its progression. Audiological tests currently used for monitoring for platinum-induced ototoxicity are presented, as well as their advantages and disadvantages. A new paediatric evaluation method is also introduced, which uses patient-reported measures and could complement audiological testing in obtaining a more comprehensive assessment of ototoxicity.Different criteria are used in the literature in order to define ototoxicity, which makes comparison among studies difficult. A critical review was undertaken on commonly-used ototoxicity grading criteria. A retrospective chart review was also performed at the Montreal Children's Hospital, characterizing the incidence of long-term ototoxicity at our institution. Work done as part of this thesis led to the design of two novel studies: a prospective cohort study evaluating the pharmacogenomics of platinum-induced ototoxicity and a randomized controlled trial evaluating the efficacy of dexamethasone as a potential otoprotective agent. Comprehensive assessment of ototoxicity, including sensitive audiological tests, appropriate ototoxicity grading criteria, and self-reported outcomes, is urgently needed, in the clinic, in order to guide interventions, and in research, in order to gain greater understanding of the incidence and burden of platinum-induced ototoxicity.Les anticancéreux cisplatine et carboplatine sont souvent utilisés et sont très efficaces contre une grande variété de cancers. Malheureusement, ces médicaments peuvent parfois causer l'ototoxicité. L'ototoxicité du cisplatine et du carboplatine consiste en acouphènes et/ou une perte auditive qui est souvent permanente, bilatérale et progressive, conduisant à des conséquences dévastatrices chez les survivants du cancer.Une détection plus précoce de l'ototoxicité permet aux cliniciens de modifier leurs plans de traitement, si possible, pour empêcher sa progression. Les examens audiologiques utilisés présentement pour la surveillance de l'ototoxicité induite par le platinum sont présentés, ainsi que leurs avantages et leurs inconvénients. Également, une nouvelle méthode d'évaluation pédiatrique est présentée. Celle-ci utilise des mesures auto déclarées, pouvant supplémenter les tests audiologiques pour obtenir une évaluation plus complète de l'ototoxicité. Différents critères sont utilisés pour définir l'ototoxicité, ce qui rend la comparaison entre études difficile. Une revue critique des critères les plus utilisés dans le classement de l'ototoxicité induite par le platinum a été menée. De plus, une étude rétrospective a été menée à l'Hôpital de Montréal pour Enfants pour caractériser l'incidence de l'ototoxicité au long-terme dans notre institution. Le travail effectué dans le cadre de cette thèse a conduit à la création de deux nouvelles études: une étude de cohorte prospective visant à évaluer la pharmacogénomique de l'ototoxicité induite par le platinum et un essai clinique évaluant l'efficacité de la dexamethasone tant qu'agent otoprotectif. Une évaluation globale de l'ototoxicité, incluant des tests audiologiques sensibles, des critères de classement appropriés, et des mesures auto déclarées, sont nécessaires, dans la clinique, afin de guider les interventions, et dans la recherche, afin d'acquérir une meilleure connaissance de l'incidence et les conséquences de l'ototoxicité induite par le platinum.
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Crowley, Cara Leilani. "Bile salt induced stress response pathways". Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/289231.
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Our lab has shown that the bile salt found in the highest concentration in human fecal water, sodium deoxycholate, induces apoptosis in several cell types including Jurkat cells as well as human colonic epithelial cells. We have also found that cells within the normal appearing flat mucosa of patients with a history of colon cancer are relatively resistant to apoptosis induced by NaDOC. The current studies test the hypothesis that sodium deoxycholate induces multiple stress response pathway s that protect against apoptosis. I have tested this hypothesis by developing and analyzing cell lines that are resistant to sodium deoxycholate-induced apoptosis and focusing on two stress-response proteins known to be activated by sodium deoxycholate, poly(ADP-ribose) polymerase (PARP) and the redo-sensitive transcription factor nuclear factor-kappa B (NF-κB). I found that PARP is protective against NaDOC-induced apoptosis, and by independently inhibiting the individual subunits of NF-κB, I found that the p65 subunit is protective, while the p50 subunit is not. Development and subsequent characterization of the NaDOC-resistant HCT-116 cell lines identified several proteins that may be responsible for the development of apoptosis resistance. These proteins will be further tested in future studies.
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Boström, Patrik. "Arousal-induced memory augmentation". Thesis, Högskolan i Skövde, Institutionen för biovetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-16586.
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Emotional events are often better preserved in memory than events without an emotional component. Emotional stimuli benefit from capturing and holding the attention of a perceiver to a higher degree than more emotion-neutral stimuli. Arousal associated with experiencing emotionally valenced stimuli or situations affects every major stage in creating, maintaining and retrieving lasting memories. Presented in this thesis were models delineating the behavioral and neurological mechanisms that might explain arousal-induced effects on subsequent memory outcome. Based on a study of relevant literature, findings were presented in this thesis that highlight amygdala activation as crucial for the enhancement of memory generally associated with emotional arousal. The amygdala modulates processing in other areas of the brain involved in memory. Heightened levels of norepinephrine, stemming from sympathetic nervous system activation, underlies observable arousal-induced memory effects and seem to be a crucial component in enabling glucocorticoid augmentation of memory. Arousal seems to further amplify the biased competition between stimuli that favors the neural representation of motivationally relevant stimuli and stimuli of a sensory salient nature. The aim of this thesis was to outline the impact of emotional arousal on different stages of memory processing, including processes for memory formation, strengthening of memory traces, and eventual subsequent retrieval.
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Ellis, Kevin Ph D. (Kevin M. )Massachusetts Institute of Technology. "Algorithms for learning to induce programs". Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/130184.
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Thesis: Ph. D. in Cognitive Science, Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences, September, 2020Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 213-224).
The future of machine learning should have a knowledge representation that supports, at a minimum, several features: Expressivity, interpretability, the potential for reuse by both humans and machines, while also enabling sample-efficient generalization. Here we argue that programs-i.e., source code-are a knowledge representation which can contribute to the project of capturing these elements of intelligence. This research direction however requires new program synthesis algorithms which can induce programs solving a range of AI tasks. This program induction challenge confronts two primary obstacles: the space of all programs is infinite, so we need a strong inductive bias or prior to steer us toward the correct programs; and even if we have that prior, effectively searching through the vast combinatorial space of all programs is generally intractable. We introduce algorithms that learn to induce programs, with the goal of addressing these two primary obstacles. Focusing on case studies in vision, computational linguistics, and learning-to-learn, we develop an algorithmic toolkit for learning inductive biases over programs as well as learning to search for programs, drawing on probabilistic, neural, and symbolic methods. Together this toolkit suggests ways in which program induction can contribute to AI, and how we can use learning to improve program synthesis technologies.
by Kevin Ellis.
Ph. D. in Cognitive Science
Ph.D.inCognitiveScience Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences
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Xiang, Kai Ph D. Massachusetts Institute of Technology. "Electrochemically-induced phase transition in olivine type cathode materials". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115608.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 159-165).
Phase transitions are commonly observed in ion storage compounds when being used in rechargeable batteries and thus, the phase behavior of ion storage compounds as electrode active materials has significant impact on battery performance. This thesis aims to understand the interplay between materials structure, phase behavior and battery performance. The effects of operating conditions, especially overpotential and temperature, on phase behavior and battery performance are also investigated. Using olivine-type phosphates (i.e. phospho-olivines) with varying composition and particle size as model system, strain accommodation mechanism within single nanoparticles (Chapter 2 to 3) and mesoscale kinetics of nanoparticle aggregates (Chapter 4 to 5) during electrochemically-induced phase transition have been systematically investigated. In the first part, phospho-olivines with varying transformation strain, from 0 - 3vol% for LiMnyFe1-yPO4 (LMFP, y<0.5), 5vol% for LiFePO4 (LFP), to 17vol% for NaFePO4 (NFP), have been studied using operando Powder X-ray Diffraction (PXD), among other methods. While small transformation strain as in LMFP is accommodated and even avoided by formation of metastable solid solution, large transformation strain as in NFP is mitigated by formation and dissolution of intermediate amorphous phase. This novel mechanism to accommodate large transformation strain may pave the way of utilizing battery materials that deem not working otherwise. In the second part, potentiostatic studies are conducted and a model modified from Avrami model is developed to quantitatively describe phase transformation progresses. The phase transition of LMFP and LFP nanoparticle aggregates is found to follow a nucleation and growth process while the growth is governed by lithium ion diffusion. Based on analysis using the modified Avrami model, more instantaneous nucleation and facile growth tend to occur when transformation strain is small (intermediate Mn content and/or small particle size), overpotential is high and/or temperature is high. And instantaneous nucleation and facile growth improve the rate capability of batteries. The relationship between phase behavior and material structure as well as operating conditions is attributed to: 1) decreasing transformation strain reduces energy barrier for both nucleation and growth; 2) increasing overpotential and temperature boost the electrochemical driving force for phase transition and promote more instantaneous nucleation and facile growth.
by Kai Xiang.
Ph. D.
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Manuel, Mario John-Errol. "Rayleigh-Taylor-Induced electromagnetic fields in laser-produced plasmas". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/80660.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references.
Spontaneous electromagnetic fields can be important to the dynamic evolution of a plasma by directing heat flow as well as providing additional pressures on the conducting fluids through the Lorentz force. Electromagnetic fields are predicted to affect fluid behavior during the core-collapse of supernovae through generation of fields due to hydrodynamic instabilities. In the coronae of stars, self-generated magnetic fields lead to filamentary structure in the hot plasma. Recent experiments by Gregori et al. investigated sources of protogalactic magnetic fields generated by laser-produced shock waves. In inertial confinement fusion experiments, self-generated electromagnetic fields can also play a role and have recently become of great interest to the community. Present day laser facilities provide a unique opportunity to study spontaneous field-generation in these extreme environments under controlled conditions. Instability-induced electromagnetic fields were investigated using a novel monoenergetic-proton radiography system. Fusion protons generated by an 'exploding-pusher' implosion were used to probe laser-irradiated plastic foils with various preimposed surface perturbations. Imaging protons are sensitive to electromagnetic fields and density modulations in the plasma through the Lorentz force and Coulomb collisions, respectively. Corresponding x-ray radiographs of these targets provided mass density distributions and Coulomb effects on protons were assessed using a Monte Carlo code written using the Geant4 framework. Proton fluence distributions were recorded on CR-39 detectors and Fourier analyzed to infer path-integrated field strengths. Rayleigh-Taylor (RT) growth of preimposed surface perturbations generated magnetic fields by the RT-induced Biermann battery and were measured for the first time. Good data were obtained during linear growth and when compared to ideal calculations, demonstrated that field diffusion near the source played an important role. At later times in the plasma evolution, 3-D cellular structures were observed for all foil types. These features were found to be analogous to previously observed filamentary field structures by Séguin et al. in laser-driven spherical targets. Face-on images of these field structures provided good data to quantitatively analyze the size of these features, not previously attainable due to the complexity of the 3-D spherical data. Work presented here demonstrates that these field structures are likely caused by the magnetothermal instability in the underdense corona.
by Mario J.-E. Manuel.
Ph.D.
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Funatsu, Jun. "Laser-assisted focused-ion-beam-induced deposition of copper". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/32617.
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Garcia, Roman Joel. "Endothelin 3 Induces Skin Pigmentation in a Kertain-Driven Inducible Mouse Model". FIU Digital Commons, 2007. https://digitalcommons.fiu.edu/etd/3835.
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Endothelin 3 (Edn3) is a ligand important to developing neural crest cells (NCC). Some NCC eventually migrate into the skin and give rise to the pigment-forming melanocytes found in hair follicles. Edn3’s effects on NCC have been largely explored through spontaneous mutants and cell culture experiments. These studies have shown the Endothelin receptor B/Edn3 signaling pathway to be important in the proliferation/survival and differentiation of developing melanocytes. To supplement these investigations I have created doxycycline-responsive transgenic mice which conditionally over-express Edn3. These mice will help us clarify Edn3J3 role during the development of early embryonic melanoblasts, differentiating melanocyte precursors in the skin, and fully differentiated melanocytes in the hair follicle. The transgene mediated expression of Edn3 was predominantly confined to the roof plate of the neural tube and surface ectoderm in embryos and postnatally in the epidermal kératinocytes of the skin. Relative to littermate controls, transgenics develop increased pigmentation on most areas of the skin. My doxycycline-based temporal studies have shown that both embryonic and postnatal events are important for establishing and maintaining pigmented skin. The study of my Edn3 transgenic mice may offer some insight into the genetics behind benign dermal pigmentation and offer clues about the time periods important in establishing these conditions. This apparently abnormal development is echoed in a benign condition of human skin. Cases of dermal melanocytosis, such as common freckles, Mongolian spotting, and nevus of Ito demonstrate histological and etiological characteristics similar to those of the transgenic mice generated in this study.
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Bowers, Matthew. "Characterization of Transformation-Induced Defects in Nickel Titanium Shape Memory Alloys". The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417649766.
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