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1
Enniss, Harris. « A Refined Saddle Point Theorem and Applications ». Scholarship @ Claremont, 2012. https://scholarship.claremont.edu/hmc_theses/33.
Texte intégralRésumé :
Under adequate conditions on $g$, we show the density in $L^2((0,\pi),(0,2\pi))$ of the set of functions $p$ for which \begin{equation*} u_{tt}(x,t)-u_{xx}(x,t)= g(u(x,t)) + p(x,t) \end{equation*} has a weak solution subject to \begin{equation*} \begin{aligned} u(x,t)&=u(x,t+2\pi)\\ u(0,t)&=u(\pi,t)=0. \end{aligned} \end{equation*}
To achieve this, we prove a Saddle Point Principle by means of a refined variant of the deformation lemma of Rabinowitz.
Generally, inf-sup techniques allow the characterization of critical values by taking the minimum of the maximae on some particular class of sets. In this version of the Saddle Point Principle, we introduce sufficient conditions for the existence of a saddle-structure which is not restricted to finite-dimensional subspaces.
2
Mokhtari, Yacine. « Stabilisation et contrôle de quelques systèmes hyperboliques ». Electronic Thesis or Diss., Bourgogne Franche-Comté, 2021. http://www.theses.fr/2021UBFCD024.
Texte intégralRésumé :
Cette thèse est consacrée à l’étude de deux problèmes issus de la théorie du contrôle des EDP. Dans un premier temps, on étudie le comportement asymptotique de la solution du système de von Kàrmàn viscoélastique unidimensionnel avec retard. On montre que ce dernier est bien posé dans un espace fonctionnel convenable en utilisant la méthode de Faedo-Galerkin. Pour établir notre résultat de stabilité, on utilise la méthode de Lyapunov en construisant une fonctionnelle adéquate. Dans un deuxième temps, on étudie le problème de la contrôlabilité et de la stabilisation par le bord pour l’équation des ondes unidimensionnelle dans un domaine non cylindrique. Pour la contrôlabilité, on utilise la méthode des caractéristiques pour construire l’unique solution du problème. Nous sommes alors capables de donner l’expression explicite du contrôle pour lequel le système atteint le point d’équilibre après un certain temps. De plus, on montre que ce temps est optimal. Pour la stabilisation, nous fournissons une condition nécessaire et suffisante pour que l’énergie du système décroisse à un taux prédéterminé. De plus, l’influence de la géométrie du domaine et l’influence d’un amortisseur dépendant du temps sont clarifiées. Dans un troisième temps, on étudie la contrôlabilité par le bord de deux ´équations d’ondes couplées par un couplage d’ordre un avec coefficients qui dépendent de l’espace et du temps. On fournit une condition nécessaire et suffisante pour la contrôlabilité exacte en haute fréquences dansle cas général et pour la continuation unique dans le cas cascadeThis thesis is devoted to the study of two problems related to the theory of control of PDE.In a first time, we study the asymptotic behavior of the solution to the one-dimensional viscoelastic von Kàrmàn system with delay. We prove that the latter system is well-posed in a suitable functional space using the Faedo-Galerkin method. To establish our stability result, we employ the Lyapunov method by using a suitable candidate functional.In a second time, we study the problem of boundary controllability and stabilization for the one-dimensional wave equation in non-cylindrical domains. For the controllability, one uses the characteristics method to build the unique solution. We will then be able to give the explicit expression of the controls for which the system reaches the equilibrium point after a certain time. Moreover, we show that this time is optimal.For the stabilization, we provide a necessary and sufficient condition that guarantees the energy decay at any desired rate. In addition, the influences of the domain geometry and time-dependent feedback are clarified. In a third time, we study the boundary controllability of two coupled one-dimensional wave equations with first-order coupling terms with coefficients depending on space and time. We give a necessary and sufficient conditions for both exact controllability in high frequency in the general case and for the unique continuation in the cascade case
3
Skipper, Emma Sue. « Investigating the genetic control of postharvest shelf life and vitamin C content in broccoli (Brassica oleracea var. italica) ». Thesis, University of Warwick, 2010. http://wrap.warwick.ac.uk/35605/.
Texte intégralRésumé :
Broccoli (Brassica oleracea var. italica) is a popular vegetable, known for its nutritional benefits. However, the marketability of broccoli is limited by a short shelf life. Broccoli is susceptible to rapid postharvest senescence, which causes visible head yellowing and wilting from dehydration. Visible quality loss is also accompanied by a decline in nutrients, resulting in a product with reduced postharvest nutritional value. These factors combined cause broccoli to become unmarketable, leading to severe wastage in the retail chain. Postharvest yellowing in broccoli has been shown to be controlled by genotype, as a doubled haploid population (MGDH) created from an F1 cross between GD33, a poor performing DH line (yellow in 2 days) and Mar34, a good performing DH line (staying green > 4 days) exhibited natural variation for shelf life. Therefore, to investigate the genetic control of quality in broccoli, the fixed mapping population was assessed for shelf life, morphological traits and vitamin C content and stability in replicated field trials. Visual inspections identified head yellowing, stem turgor and bud compactness as the main traits affecting the marketability of broccoli. Two methods to quantify head yellowing were also evaluated. Spectrophotometer readings were found to be more sensitive than Image J in detecting colour change, but Image J data was more reproducible. Vitamin C quantification using HPLC, confirmed that natural variation was present in the MGDH population at harvest. Vitamin C content during postharvest storage, detected by plate assays, found vitamin C to be unstable, degrading quickly after harvest. A unique broccoli x broccoli linkage map, covering ~72.9% of the B.oleracea genome, was also constructed by genotyping the MGDH population with SSR and AFLP markers. QTL analysis of the trait data positioned 48 significant QTL in the linkage map for head yellowing (4), colour co-ordinates (17), morphological traits (17), bud quality (2) and postharvest vitamin C content (3) and stability (5). The identification of QTLs associated with the above traits has provided useful information for breeders to breed for improved nutritional and quality in broccoli using marker-assisted selection (MAS). The location of QTLs has also provided targets for fine-scale mapping and for the identification of candidate genes underlying traits.
4
McDonald, Paul Charles. « Cryogenically cooled amplifiers for deep space communication ». Thesis, University of Southampton, 2001. https://eprints.soton.ac.uk/35405/.
Texte intégral
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Vignaga, Elisa. « The effect of biofilm colonization on the stability of non-cohesive sediments ». Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3505/.
Texte intégralRésumé :
In the past decades, engineers have started to realize the importance of the interaction between vegetation, biota and water flow, in riverine and marine environments; a discipline that has been named “Eco-Hydraulics”. Scientists have valued this coupled phenomenon for much longer than their engineering colleagues. As early as 1970, marine researchers presented the evidence that colonies of micro-organisms might alter the stability of fine cohesive sediments (Neuman et al., 1970). However traditional models of sediments transport (e.g. Shields, 1936) have been derived using abiotic sediments and did not consider that most wet surfaces would soon be colonized by micro-organisms and their extracellular polymeric substances (EPS), a combination called “biofilm” (Lock, 1993). Scientists during the 1990s, after observing this phenomenon in the field, coined the term “biostabilization”. During this period they showed that colonies of cyanobacteria and diatoms coating fine sand or cohesive sediments can increase their stability by up to 960% compared to abiotic sediments (Grant and Gust, 1987; Dade et al, 1990; Paterson 1997). Only recently have engineers started to take into consideration the effect of such increased cohesion and adhesion due to biogenic forces within the sediment transport model (Righetti and Lucarelli, 2007); yet all of those studies have low applicability because they are linked to specific environmental conditions. Moreover no data are available on the effect of biofilm on larger sediments (e.g. coarse sand and gravel). The present thesis provides experimental data carried out in a flume laboratory pertaining to biostabilization of non-cohesive coarse sand and gravels at a scale representation of a real river system (from 0.2m to 1m). Four sediment substratum (glass spheres of D50 = 1.09mm and 2.00mm; sand of D50 = 1.20mm and gravel of D50 = 2.20mm) were colonized under unidirectional flow by a cyanobacterium (Phormidium sp.) for between 1 and 10 weeks. The increase in erosion threshold for biotic sediment is then investigated using a series of different methods ranging from traditional sediment transport techniques (e.g. Yalin, 1972), to image thresholding and particle image velocimetry (PIV) assessments of flow modification due to biofilm presence. Moreover, tensile strength analysis of ex-situ biofilm/substratum specimens will be presented to understand better the mechanical property of this composite material. Data indicates that: i) biostabilization of sediments in the range of coarse sand and gravel occurs (9%-150% more shear stress required to induce entrainment compared to abiotic sediments) but to a lower extent compared to critical entrainment thresholds for fine sand and cohesive sediments (Paterson, 1997); ii) flume experimentation can be employed to control specific variables affecting biostabilization and could help to unfold the complicated interactions between environmental variables, and the affect of flow on the growth and strength of biofilm colonization over sediments; iii) strong biofilm growth generated a more uniform velocity field, with reduction in shear stress (up to 82% compared with abiotic sediments) and decreases in roughness length of the bed (up to 94% compared to abiotic sediments); iv) Composite biofilm/substratum specimens presented a clear elastic behaviour when tensile tested; v) Conventional models of sediment transport (e.g. Wiberg and Smith, 1987) do not consider the presence of biofilm and will not work in the case of bio-mats smoothing the surface of the bed; hence the need for new models which include the biofilm elasticity and the bio-mat smoothing process. This thesis suggests two theoretical examples where the biofilm action is considered at a grain to grain and bio-mat scale.
6
Mazzoli, Marco. « Market concentration, credit institutions and the macroeconomy ». Thesis, University of Warwick, 1994. http://wrap.warwick.ac.uk/3505/.
Texte intégralRésumé :
Chapter one is a brief discussion of a few methodological premises. The second chapter is meant to show (by means of a theoretical analysis) the effective macroeconomic relevance of oligopsony in the market for credit. This is done by using two models. In the first (simplified) model - where the behaviour of the supply function of bank credit to industrial firms is captured by a "Cobb-Douglas" reduced form - an exogenous decrease in the market power of the industrial firms on the credit market increases the effectiveness of monetary policy. In the second model, where the banking sector behaves consistently with the portfolio allocation theory, the results are weakened: it is still true that, apart from extreme cases, reductions in the market power of industrial firms in the credit markets increase the macroeconomic level of investment and affect the monetary policy multiplier, but the sign of the latter effect becomes ambiguous and depends on the analytical forms of the behavioural functions. Both models, however, show that modifications of the market structure in the banking sector have, in general, macroeconomic effects. The third chapter suggests an interpretation of the phenomenon of “securitization" on the basis of Williamson's [1985] contractual framework. It is pointed out that in securitized financial systems substitutability between securities and intermediated credit is an empirically relevant phenomenon that makes the demand for bank credit to industry more unstable than the supply. For this purpose, a comparative econometric analysis has been performed with British and German data, because the two countries had (apart from the phenomenon of securitization) many similarities in their regulatory systems, as well as in the degree of concentration of their banking sectors and in the magnitude of the respective economies, at least until German Unification. The analytical form of the bank credit supply function is based on the "credit view". This specific aspect of the behaviour of banks is analyzed in Chapter 4, which contains an empirical analysis (performed with Italian data) of the free liquidity ratio for commercial banks, interpreted on the basis of the recent literature on investment decisions under conditions of investments' irreversibility and uncertainty. Chapters 5 and 6 examine the interactions between industrial firms and financial intermediaries in a "microeconomic" perspective. The focus is on the investment decision, and one of the main concerns is to perform a theoretical and empirical analysis on the connections between risk, cost of capital and investment decisions. Chapter 5 contains an empirical analysis of the firms' investment decision based on a theoretical model where the decisions concerning investment and the firms' financial structure are taken simultaneously. The results are not conclusive, in part because of the complexity of the causal links among market structure, investment and financing decisions suggested by various contributions in finance as well as in industrial economics. The study of such causal links is precisely the concern of Chapter 6, which contains an analysis of the implications of a few alternative hypotheses (based on precise results of the industrial economics literature) on the link existing between the cost of capital, the market structure and the profit margins.
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Thomas, John Christopher. « Footwashing in John 13 and the Johannine community ». Thesis, University of Sheffield, 1990. http://etheses.whiterose.ac.uk/3505/.
Texte intégralRésumé :
This dissertation examines John 13: 1-20, the pericope which describes Jesus washing the feet of his disciples. For a variety of reasons, there is no scholarly consensus concerning the meaning of this passage. In addition, very little reflection has been devoted to the place religious footwashing may have held in the Johannine community. This dissertation reexamines the fundamental issues raised by the passage and investigates the likelihood that footwashing was a community rite. Chapter one gives an overview of the prominent interpretations of John 13: 1-20 in the history of interpretation. This chapter also presents an elaboration of the dissertation's purpose, together with a preview of and justification for the methodology employed, which includes text-critical, background-historical, literary-exegetical, and historical-reconstructive components. In view of the decisive bearing on interpretation, the textual problem found in John 13: 10 receives considerable attention in chapter two. Here a decision is made in favor of the inclusion of the longer reading, because of superior external evidence and internal probability. In chapter three a survey of the practice of footwashing in Jewish and Graeco-Roman antiquity uncovers first-century attitudes to footwashing, which in turn leads to a more informed interpretation of footwashing's significance in John 13. The survey reveals that footwashing functioned as an act of hospitality, an expression of love, a sign of servitude, and a sign of preparation generally. Chapter four is devoted to a literary and exegetical analysis of the text of John 13: 1-20. This investigation indicates the pericope's literary context within the Fourth Gospel, as the first episode in both the "Book of Glory" (John 13-21) and the farewell materials (John 13-17). The role of the disciples in the preceding narrative (John 1-12) is also explored. An exegetical study follows, which seeks to interpret the text of John 13: 1-20 as it now stands in the Fourth Gospel. The analysis finds that the footwashing of John 13 is best understood as a sign for the forgiveness of the disciples' post-conversion sin. The analysis concludes with reflection scholarly discussion about the literary unity of the footwashing pericope. The evidence which makes likely that the Johannine community engaged in footwashing as a religious rite is explored in chapter five. This examination utilizes information from the implied readers in the Fourth Gospel, from actual readers of the Fourth Gospel in the early church, and from the practice of footwashing in early Christianity. An examination of similar categories of evidence suggests that footwashing signified the forgiveness of post-conversion sin for the Johannine community. The final section of the dissertation is devoted to a set of conclusions and suggestions for future research.
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Harrington, Jon. « A politicised epistemology and its effects upon universities and their management of societal ontology ». Thesis, Northumbria University, 2009. http://nrl.northumbria.ac.uk/3505/.
Texte intégralRésumé :
In recent years the universities have changed from pre-enlightenment "protectors" of societal knowledge to typically modern "business" orientated bureaucracies. It is argued that as a consequence, their status has also changed from one of independent "observer" into that of "product producer"; driven particularly by their newly adopted managerialistic principles, aimed at making them more "business" orientated. This has been fuelled by the domination of a scientistic (Positivist) epistemology throughout the university sector, which emerged from an important philosophical debate, in the sixties, between Kuhn and Popper. Establishing facticity, based upon scientistic methodology, in research as supreme; it allowed for a marriage of convenience between the managerialistic ambitions of the new elite and the worldly theory it purported, as a self-fulfilling justification and prophecy of their actions. Debate in this area has been centred upon the practicalities of managing such a change and its consequences in terms of organisation and management efficiencies. Discussion regarding longer-term effects of whether such a change in the universities, driven in particular by their business schools and senior management, might have a more fundamental impact upon the way we theorise and think about ourselves, is rarely covered. It is contended that such omission is misplaced. The universities' traditional role in society as guardians of our ontological theorectics is being downgraded by increasing demands for them, from government bodies and the like, to behave akin to profit making organisations. This thesis is contending, therefore, that as a consequence of university management search for greater efficiencies, the epistemological frameworks for research, and subsequent theorectics, in the universities have become politicised. It is argued that eventually this will affect society's ontological frameworks and hence change the way we, as individuals, regard our reality. Central to this, is the premise that given the dominant scientistic method, alluded to above, is tainted by political intrusion, it would be inappropriate to use it as a method of analysis. However, it is also contended that constructivist ethnomedology is similarly, and ultimately, dependent upon rationo-factual research and therefore is inappropriate. With the use of a negative dialectic, instituted by early Frankfurt School discussion, this work, therefore, seeks to establish a new facticity independent, universal theorectic based upon proto-epistemological states. The aim is to lay bare the corruptible nature of the relationship between politicised epistemology and its consequential ontological state and thus demonstrate the potentiality of the danger facing our universities and society.
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Ranger, Graham Frank. « What are the professional development needs of Heads of international schools in India and how may they be met ? » Thesis, Durham University, 2012. http://etheses.dur.ac.uk/3505/.
Texte intégralRésumé :
What are the professional development needs of Heads of international schools in India and how may they be met? Fuelled by almost a decade of high economic growth, the growth in number of international schools in India is at an unprecedented high. Increasingly, schools are opening to serve the long-term resident as well as the expatriate population. The fastest area of growth is in proprietorial schools, owned and governed by business entrepreneurs. Invariably such schools look for an overseas curriculum, usually through the International Baccalaureate programme. International schools are a largely unregulated sector of schooling in India, in fact, not a sector at all. The leaders of such schools are adrift from any India-wide professional support system or system of accountability, beyond the immediate, local level. The culture of schools is competitive rather than collegial, especially within an urban (metropolitan) area. I am investigating the professional development needs of the Heads of School, developing competencies and standards for them, and proposing ways to offer systemic professional support. My research gathers qualitative data and uses grounded theory techniques of axial coding. My literature analysis is divided into an analysis of the literature about international schools and their origins and their relevance today, about leadership development and thirdly concerning school improvement. The Heads of School are struggling to cope and flourish professionally. Foreign Heads of School have particular difficulties in adjusting to the work environment of India. The international organisations, one of which, the IB, may have been said to have helped fuel growth without being able to ensure schools have appropriate support or quality assurance, is putting structures in place to support schools. But, no-one has an overview beyond their commercial and professional interest. The optimum way forward, my research concludes, is if an India-wide association is able to work with international partners to use agreed leadership standards and competencies, to support schools in recruiting and developing Heads, including measuring their performance to improve accountability.
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Landesman, Tucker. « Remaking Rio de Janeiro through "favela integration" : the politics of mobility and state space ». Thesis, London School of Economics and Political Science (University of London), 2016. http://etheses.lse.ac.uk/3505/.
Texte intégralRésumé :
This thesis examines how states develop and implement urban planning and governance policies and programmes in response to segregation and socio-spatial inequalities. Rio de Janeiro has long been constructed as both a “marvellous city” and as strictly “divided” between the so-called formal city and the self-built favelas that developed into “consolidated” neighbourhoods. While never granted full legal tenure and continuously denied basic rights as guaranteed in the 1988 “Citizens’ Constitution,” public policy in the late twentieth century recognised the permanence of the favelas and state interventions evolved from demolishing to “upgrading.” Since the early 2000s, the municipal, state-province, and federal governments have all pursued objectives to “integrate” the favelas. These include participatory urban planning interventions, militarised occupation and policing of favelas, implantation of social and cultural infrastructure, and technocratic good-governance projects. I argue that these combined efforts amount to a new paradigm of “favela integration,” and I seek to understand how “favela integration” is produced and contested; in what ways state interventions meant to “integrate” the favelas transform urban space; and how techniques of urban planning and governance establish favela space as legitimate and constitutive of the city. Based on 18 months of mixed-method qualitative fieldwork, and drawing on the literatures of landscape and critical mobilities, I argue that “favela integration” is hegemonically defined through state facilitation and regulation of flows of people, goods, and services in and out of the favelas. Discursively produced based on liberal notions of citizenship and favela residents’ right to the city, I use critical mobilities analysis to reveal how “favela integration” reproduces spatial inequalities. I then consider the paradigm as a state spatial strategy of territory. I build on contemporary theories of state space and territory as effect and consider how planning, technocratic governance, and infrastructure employ social technologies to bridge the favela/city binary and produce the “integrated city.” I engage with literature concerning state spatiality under neoliberalism to examine how “favela integration” follows hegemonic socio-economic ideology, but I argue for a nuanced understanding of the state and discuss how such ideology is contested at various scales.
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Gibbs, Raelton. « Standing in the shadows : faith, homelessness and troubled lives ». Thesis, University of East London, 2013. http://roar.uel.ac.uk/3505/.
Texte intégralRésumé :
This research studies five homeless people’s experience focusing on two key research questions - what is the place of faith and a faith based organisation in the lives and minds of people using the service and what does an in depth analysis of the emotional biographies of a gr oup of homeless people tell us about the psychic, material and spiritual needs that they bring to the centre? Each person interviewed was of no faith or a different faith to the host organisation. Using Biographical Narrative Interpretive Method and Grounded Theory the research generated in depth insights into the life experiences of some of the most vulnerable in our society, giving them a voice. Based on a single narrative seeking question, the interviews disclose long histories of personal and social suffering, and a connection between those histories and peoples’ pathways into homelessness, both external and internal. There are traumatised people for whom literal homelessness is not the outcome, but the path into homelessness for all the research subjects suggests a typical picture of people balanced on a knife-edge between a number of sets of pairings including meaning and meaningless, hope and despair and life and death. To aid u nderstanding I think of these subjects as distributed along a spectrum, with some occupying positions closer to hopelessness, despair or suicide, and some in more hopeful or connected states. All of this is both what brings people to the host organisation, and what they bring into that organisation. The research findings enable better understanding of key issues affecting homeless people not only for faith-based organisations but for all that work with social exclusion and homelessness. Noting the occurrence of similar emerging issues over each of the case studies what begins to emerge are a number of implications for practice. These include the importance of developing meaningful relationships; the need to meet service users higher needs particularly spirituality from the point of admission, the importance of a full knowledge of the housed history, the importance of giving the opportunity to explore important life issues and to be listened to. A possible implication of the research undertaken relates to the organisation itself . The way the organisation does or does not respond , introducing the notion that it operates defences against anxiety and pain drawing on its own theological dogma, an ideology that functions as a defence against being over whelmed. The organisation’s position within the homelessness field is also consider ed. Finally there are the defences towards the inner projections of the residents. It is how the organisation responds to these elements that the research suggests assists or hinders the progress of the homeless person’s route out of homelessness.
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Briard, Jennie Grace. « The Rational Design and Use of Novel Small-Molecule Ice Recrystallization Inhibitors for the Cryopreservation of Hematopoietic Stem Cells and Red Blood Cells ». Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35005.
Texte intégralRésumé :
Over the past few decades, there has been an increase in the development of new cellular therapies used for the treatment of various conditions. Thus, the rapid development of therapies requiring transfusion and transplantation of cells has resulted in a need to preserve these cellular therapy products. Cryopreservation is the only currently used method for the long-term storage of cells. The most commonly used cryoprotectants are 10% dimethyl sulfoxide (DMSO) for hematopoietic stem cells (HSCs) and 40% glycerol for red blood cells (RBCs). DMSO fails to protect the functionality of HSCs after cryopreservation and therefore, up to 20% of HSC transplantations fail to engraft. The glycerol in thawed RBC units must be removed to <1% to prevent intravascular hemolysis which is time-consuming. Thus, there is an urgent need to develop improved cryoprotectants for HSCs and RBCs.
DMSO and glycerol are unable to control ice recrystallization which is a major source of cellular injury during cryopreservation. Therefore, compounds with the ability to inhibit ice recrystallization could represent a new class of cryoprotectant with a novel mechanism of action.
This thesis focuses on the rational design of small-molecule ice recrystallization inhibitors. The key structural attributes required for ice recrystallization inhibition (IRI) activity are investigated. The amphiphilic balance required for IRI activity is explored. Furthermore, two new classes of small-molecule IRIs containing aromatic rings were rationally designed. As a result, several very highly IRI active molecules were discovered.
The use of IRIs to improve the cryopreservation of HSCs and RBCs was explored. A number of IRIs improved the post-thaw functionality of HSCs. Supplementation of the current cryoprotectant solution with IRIs resulted in an increase in CFU recovery and frequency of multipotent progenitors. This would reduce the percentage of engraftment failure and allow for a larger proportion of cord blood banks’ inventory to provide an adequate dose for patients requiring transplants. Several IRIs were found to be effective cryoprotectants for RBCs with reduced amounts of glycerol. This could reduce the deglycerolization time for RBCs. These results demonstrate the potential of small-molecule IRIs to improve the current cryopreservation procedures for important cellular therapy products.
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Lefebvre, Claudine. « Presence, Bioconcentration and Fate of Galaxolide and Tonalide Fragrances in the North Saskatchewan River, Edmonton ». Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35105.
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Synthetic musks are incorporated extensively in personal care products to improve their scent, increase their fragrance stability, and prolong their shelf-life. As a consequence, these persistent musks are being released at a considerable rate by wastewater treatment plants and are frequently detected in surface water, bottom sediment, air, and aquatic biota near urban areas. In addition to their hydrophobicity, two synthetic musks, Galaxolide (HHCB) and Tonalide (AHTN), were reported to cause endocrine disruption in fish species. Although most of the toxic effects in past studies were observed at high doses, HHCB and AHTN were shown to bioaccumulate very differently depending on the aquatic species tested. As bioaccumulation and fate of contaminants are important considerations when regulating persistent chemicals, an improved understanding of the bioaccumulation potential of these chemicals is needed. In this thesis, an assessment of the presence, bioconcentration and fate of HHCB and AHTH was provided in an area exposed to the effluent of the Gold Bar wastewater treatment plant in the North Saskatchewan River (Edmonton). HHCB and AHTN were quantified in fathead minnows (Pimephales promelas) exposed downstream of the effluent, with an adapted method for analysis of musks in fish, using PAHs as recovery standards. Method development and recoveries are summarized. Highest bioconcentration factors were 24,500 and 22,300 for HHCB and AHTN respectively, and were observed 1 km downstream of the outfall. Musks were found in most fathead minnows exposed at reference sites upstream as well as at the furthest site, 9.9 km from the outfall. Musk concentrations in water at these sites were used in the assessment of the fate of HHCB and AHTN by fugacity modeling with QWASI software. In order to assess fate, a contaminated portion of the North Saskatchewan River was divided in a series of compartments that were each treated as connected individual water bodies. HHCB and AHTN losses were mostly due to water advection and sedimentation fluxes. Model fit was assessed by comparing predicted to measured data.
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Glynn, Brittany A. « A Phenomenological Exploration of Joy during Zumba Exercise : Form, Feeling, and Flow(s) of E-motion ». Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35205.
Texte intégralRésumé :
The purpose of this doctoral dissertation was to explore the experiences of joy during Zumba exercise. A hermeneutic phenomenological methodology was employed to explore the essential structures or essence(s) of joy. Seven long-term Zumba patrons (one male, six females) participated in this study. Each participant engaged in three phenomenological interviews, observation by the principal investigator, and were invited to keep a journal of their Zumba experiences throughout the duration of the five-month study. One final focus group was conducted at the end of the individual interviews, which four participants attended. In addition, the principal investigator oriented to the phenomenon of joy in Zumba firsthand by experiencing weekly Zumba exercise classes for the period of one year. Three articles were constructed to present the findings from this research. The first article explores the visible, bodily forms and kinaesthetic feelings during Zumba exercise. Phenomenological analysis resulted in exploring joy through stomping, bouncing, and swaying experiences of e-motion. The second article explores somatic flow through an existential connection of body-other-world. Phenomenological analysis resulted in exploring somatic flow through rhythmical and effervescent connections via motions, gestures, postures, and felt connection. Finally, the third article explores the researcher’s bodily experiences while engaging in the phenomenological research process. Three experiential accounts are explored in this inquiry, including: participating in a Zumba exercise class; engaging in a phenomenological interview; and the process of writing and re-writing the experiences of joy. This doctoral research thus offers opportunities to sense and understand joy as a motile phenomenon during Zumba exercise classes and brings attention to the various ways joy may look, feel, and flow through felt connections of e-motion.
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Barnes, Christopher. « Cretaceous-Paleogene Low Temperature History of the Southwestern Province, Svalbard, Revealed by (U-Th)/He Thermochronometry : Implications for High Arctic Tectonism ». Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35305.
Texte intégralRésumé :
The High Arctic has been a complex region of collisional and extensional tectonism through the Mesozoic and Cenozoic. Svalbard, the sub-aerial exposure of the northwestern Barents Shelf, is an excellent natural laboratory investigating for High Arctic tectonism. Using apatite and zircon (U-Th)/He low-temperature thermochronometry combined with geological constraints, we resolve Cretaceous through Paleogene time-temperature histories for four regions of the Southwestern Province. Our results indicate a temperature gradient from south to north of ~185°C to >200°C, respectively, as a consequence of sedimentary burial and elevated geothermal gradient ( 45°C/km) from High Arctic Large Igneous Province activity. Late Cretaceous cooling affected all regions during regional exhumation related to initial rifting in the Eurasian Basin. During Eurekan tectonism: 1) our models indicate a heating event (55-47 Ma) characterized by overthrusting and a lack of erosion of the West Spitsbergen Fold-and-Thrust Belt, with Central Basin sediments derived from northern Greenland, followed by 2) a subsequent cooling event (47-34 Ma) corresponding to a shift in tectonic regime from compression to dextral strike-slip kinematics; exhumation of the WSFTB coincided with strikeslip tectonics.
16
Paulin, Christine Charlotte. « Articulation entre facteurs contextuels relatifs aux mécanismes délibératifs et processus de formulation des politiques publiques : le cas des politiques sociales au Nouveau-Brunswick ». Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35505.
Texte intégralRésumé :
Cette recherche se penche sur l’analyse comparée de deux cas particuliers de politiques publiques au Nouveau-Brunswick : la politique familiale et la politique sur la réduction de la pauvreté. Elle pose la question suivante : Comment les facteurs contextuels influencent-ils le processus de formulation des politiques sociales mené à l’aide d’instruments délibératifs? S’appuyant sur les fondements méthodologiques de la recherche inductive, elle s’inscrit dans la continuité des travaux menés dans le domaine de la démocratie délibérative et des instruments d’action publique et vient ainsi enrichir les écrits en administration publique dans ce champ. Ancrée dans une approche fonctionnaliste, notre recherche analyse la conception et la mise en œuvre des dispositifs délibératifs (plus précisément l’étude du Dialogue public/citoyen), ainsi que le processus de formulation des politiques publiques qui en découle.
En nous inspirant principalement des travaux de Abelson et Gauvin (2006), nous avons initialement identifié cinq grands axes d’analyse (facteurs contextuels) : les caractéristiques sociopolitiques (FC1); les facteurs communautaires (FC2); l’enjeu public (FC3); les attributs organisationnels (FC4) et les aspects du processus décisionnel (FC5) pour mener cette analyse. Nos travaux nous ont permis d’identifier plusieurs dimensions associées à chacun de ces cinq facteurs contextuels et qui ont une influence certaine sur l’ingénierie des instruments délibératifs et le processus de formulation des politiques publiques. Nos constats de recherche permettent d’atteindre deux grands objectifs : 1) décrire et expliquer les principaux facteurs contextuels qui conditionnent les dispositifs délibératifs spécifiquement utilisés lors des processus de formulation des politiques sociales au Nouveau-Brunswick; et 2) développer et définir un cadre analytique qui tient compte de la réalité et des spécificités contextuelles dans le domaine de l’élaboration des politiques sociales au sein de la conjoncture néo-brunswickoise.
En plus d’identifier et d’expliquer les éléments contextuels qui ont un impact prépondérant sur notre objet d’étude, l’analyse menée permet de mieux comprendre la trajectoire des changements et des spécificités qui influencent les instruments délibératifs utilisés au Nouveau-Brunswick, dans une optique de formulation des politiques sociales. Les principaux constats de recherche se traduisent notamment par l’ajout de nouveaux facteurs et dimensions contextuelles au modèle conceptuel original proposé par Abelson et Gauvin (2006) qui ont un degré d’influence plus élevé que les autres sur la conception et la mise en œuvre des dispositifs délibératifs, de même que le processus de formulation des politiques publiques. Deux dimensions favorables et trois contraignantes ressortent de l’analyse. Les premières réfèrent aux caractéristiques des principaux acteurs non gouvernementaux – Groupes/réseaux provinciaux à désignation bilingue (nouvelle dimension qui s’ajoute dans le facteur contextuel portant sur les caractéristiques sociopolitiques) et à la transformation et compréhension du rôle des acteurs traditionnellement et nouvellement impliqués dans le processus de formulation des politiques publiques – « décideurs citoyens » et « décideurs partenaires » (nouvelle dimension qui s’ajoute dans le facteur contextuel portant sur le contexte décisionnel). Les secondes se rapportent aux attributs organisationnels — culture/pratiques institutionnelles courantes au sein de la fonction publique néo-brunswickoise et gouvernance en silos (facteur contextuel portant sur les attributs organisationnels), au rôle de l’information (nouveau facteur contextuel) et à la caractéristique linguistique (nouveau facteur contextuel).
Notre étude permet de répondre aux sous-questions de recherche suivantes : Quels sont les instruments délibératifs utilisés dans la formulation des politiques sociales au Nouveau-Brunswick? Quels sont les principaux facteurs contextuels intrinsèques aux instruments délibératifs étudiés? De quelle(s) façon(s) se manifeste l’influence de ces facteurs contextuels lors de la conception et de la mise en œuvre des instruments délibératifs? Comment se manifeste l’influence de ces facteurs contextuels sur l’élaboration des politiques sociales au Nouveau-Brunswick?
En somme, cette recherche s’avère pertinente pour la compréhension de trois dimensions importantes en administration publique : 1) la conception et la mise en œuvre de nouveaux instruments de formulation des politiques publiques, 2) les principales conditions d’élaboration des politiques sociales et 3) la présentation du contexte des politiques publiques au Nouveau-Brunswick (en tenant particulièrement compte de la dimension linguistique de cette province officiellement bilingue).
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Lummiss, Megan. « Self-Perceptions of Twice-Exceptional Students : The Influence of Labels and Educational Placement on Self-Concept for G/LD Post-Secondary Students ». Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35605.
Texte intégralRésumé :
Research has shown self-concept to be a significant influence of later success in life, yet studies have rarely focused on the perceptions of students in all educational placements and achievements – specifically, those identified as gifted and with a learning disability (G/LD) (Rudasill, Capper, Foust, Callahan, & Albaugh, 2009). Adopting a qualitative case study approach, and guided by the Marsh/Shavelson model of self-concept (1985) and the Social Identity Theory (1986), this study explored 1) how G/LD students perceive the development of his or her self-concept over time and 2) how labelling and educational placement interact with the development of self-concept. A Body Biography and a discussion/ semi-structured interview were used to explore these questions with eight English-speaking post-secondary G/LD students. During the discussion/ semi-structured interview, participants discussed their completed Body Biography and responded to questions focused on self-perceptions of educational placement, labels, social identity, group membership, and self-concept. Findings of the study revealed that participants tended to perceive the gifted and LD components of the G/LD identification as separate components, rather than as a whole identification; participants appeared to consider themselves as part of a gifted in-group when reflecting upon their strengths and within a LD in-group when reflecting upon their weaknesses; and educational placement experiences exerted a strong influence upon participants’ self-concepts, depending on how well they perceived their educational placement experiences met their academic needs. Overall, the domains of self-concept were very closely related to one another, with academic, social, and emotional self-concepts being the most influenced by identification, labels, and educational placement. The findings from this study support the notion that each G/LD student is unique and there is no singular best method of identification, nor is there one specific educational path that meets the educational needs of all G/LD students.
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Chen, Liyu. « A Case Study of Dissolved Oxygen Characteristics in a Wind-Induced Flow Dominated Shallow Stormwater Pond Subject to Hydrogen Sulfide Production ». Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35805.
Texte intégralRésumé :
Stormwater ponds (SWPs) are becoming increasingly important due to the negative impacts on flood mitigation and water quality control that results from rapid urbanization. These ponds are not only designed to control the discharge of large precipitation and snow melt events, but also to mitigate the water quality of the retained stormwater. Consequently, improper design and maintenance may lead to hypoxic conditions in SWPs, which result in poor water quality and generation of noxious gases. Riverside South Stormwater Pond II (RSPII) in Ottawa periodically experiences low dissolved oxygen (DO) concentrations and subsequently hypoxic conditions at depth in the pond, especially during summer days with less precipitation and winter ice covered periods. Hydrogen sulfide gas (H2S) has been generated and released into the ambient atmosphere during these periods of lesser water quality. Hence, there is a need to understand how DO spatial distribution and seasonal change trigger and affect H2S production. The conventional shallow design criteria of SWPs likely cause these systems to be susceptible to wind conditions. Very few research has demonstrated the correlation between wind-driven hydraulic performance and detained stormwater quality. Hence an understanding of pond-scale mixing generated by wind-induced flow and the subsequent correlation to DO concentrations and stratification in SWPs are important to understanding the water quality and performance of these systems, especially in a wind-induced flow dominated SWPs.
The overall research objective is to develop a comprehensive understanding of hypoxic conditions of SWPs and to investigate the impact of wind induced hydraulics on DO seasonal characteristics and the subsequent production of H2S. RSPII was shown to experience lower DO and longer hypoxic conditions than an adjacent reference pond (RSPI) at both non-ice covered and ice covered months. In addition, hypoxia was shown to be initiated at the outlet of RSPII where the depth of the pond was a maximum. Interestingly, chlorophyll-α blooms were observed during ice covered conditions in the study, with synurids, tabellaria, and asterionella being identified as the dominant species. A bottom-mount acoustic Doppler current profiler (aDcp) was used to collect small wind-generated currents in RSPII. The three-dimensional current and DO model produced by MIKE 3 (DHI software) suggests a conclusive result of pond scale mixing produced by wind-driven flow as well as countercurrents near the bed opposite to wind direction. A wind dominated circulation was shown to be generated even with moderate wind speed, and with a higher wind condition pond-scale complete DO mixing was created. The MIKE 3 simulation further provided a comprehensive understanding of the correlation between wind-induced hydraulics and DO concentrations distribution in a shallow stormwater pond. Therefore, this research demonstrates that wind is an essential hydraulic driver in shallow ponds, which also likely affects water quality by initiating pond mixing.
19
Meng, Fanqin. « Electrical Heating Vest for Heart Failure and/or Hypertension Therapy ». Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35905.
Texte intégralRésumé :
Purpose:
To develop a lightweight, safe, and controllable electrical heating vest for heart failure and/or hypertension patients.
Methods:
a. A literature review related to the topic was conducted.
b. A model of a simplified human body thermoregulation system was developed and simulated. It was used to predict the power requirement of the battery to increase core body temperature up to 1 Celsius degree (°C).
c. A prototype with a smart controller was developed
d. In-vitro tests of the prototype were conducted to assess performance and safety.
e. The prototype was tested on 10 healthy human volunteers and the results were analyzed.
Results:
a. An average core body temperature increase of 0.3 °C (P<0.05) was observed in healthy human volunteer tests within 30 minutes.
b. The vest induced decreases in systolic blood pressure of 5.5 mmHg and diastolic blood pressure of 4.8 mmHg on average.
Conclusions:
A carbon-fiber vest can increase body core temperature by 0.3°C lowering systolic and diastolic blood pressure, which can be potentially used for helping heart failure and/or hypertension patients.
20
Ghelfi, Ariane. « Efeitos toxicológicos do diclofenaco em peixes Rhamdia quelen ». reponame:Repositório Institucional da UFPR, 2014. http://hdl.handle.net/1884/35405.
Texte intégralRésumé :
Resumo: Entre os contaminantes emergentes que vem impactando os corpos d'água estão os fármacos. A presença de medicamentos tem sido detectada em diversos países não só na água como no solo e em sedimentos. Muitas vezes, os tratamentos de efluentes tradicionais não são eficazes na eliminação dessas substâncias, e desta forma elas ficam disponíveis no ambiente, oferecendo risco a organismos aquáticos e terrestres por serem potencialmente tóxicos. Entre esses fármacos está o diclofenaco, um anti-inflamatório amplamente prescrito mundialmente, que possui ação analgésica, anti-inflamatória e antipirética. Este trabalho objetivou avaliar os potenciais efeitos agudos tóxicos deste medicamento para o ambiente aquático, através de um bioensaio com peixes Rhamdia quelen, uma espécie nativa da América do Sul. Organismos juvenis foram expostos nas concentrações de 0,2, 2 e 20 ?g/L de diclofenaco sódico em água. Após 96 horas de exposição os animais foram anestesiados para a coleta de sangue e posteriormente eutanasiados. No fígado e rim posterior foram avaliados os biomarcadores bioquímicos de estresse oxidativo CAT, SOD, GPX, GSH, GST e LPO e para avaliar a genotoxicidade foi utilizado o ensaio cometa. No sangue foram avaliados biomarcadores hematológicos e o genotóxico. No fígado não foi evidenciada nenhuma alteração nos biomarcadores bioquímicos e na genotoxicidade. No rim foi observado aumento na atividade da SOD nas concentrações de 2 e 20 ?g/L, diminuição da LPO e de dano genético na maior concentração de diclofenaco testada. Nos resultados dos ensaios hematológicos o número de eritrócitos diminuiu nas concentrações de 0,2 e 2 ?g/L, o número de neutrófilos aumentou na maior concentração e o de monócitos apresentou aumento na concentração de 2 ?g/L. O número de linfócitos e mononucleares diminuiu nas concentrações de 2 e 20 ?g/L. Esses resultados sugerem que a exposição aguda ao diclofenaco provoca alterações hematológicas e renais em R. quelen, apresentando risco potencial de afetar essa espécie e consequentemente o ecossistema no qual encontra-se inserida.
21
Souza, Claudio Alexandre de. « Territorialidade nas ações de responsabilidade social empresarial dos resorts do Brasil ». reponame:Repositório Institucional da UFPR, 2014. http://hdl.handle.net/1884/35105.
Texte intégralRésumé :
Resumo: O Brasil possui instalado os meios de hospedagem tipo resorts em todas as suas regiões político-administrativas. Estes tipos de meios de hospedagem possuem no caso do Brasil, características relativas ao seu tamanho e a sua operação que os diferenciam dos resorts em outros países. Aliadas as singularidades ambientais, socioculturais e econômicas das regiões do Brasil os resorts são um objeto de estudo quanto as suas respectivas relações sociais para com os demais atores/stakeholders aqui estudados. Estas são bases para que neste estudo tenha-se o objetivo de analisar a territorialidade das ações de relações sociais das ações de responsabilidade social empresarial dos resorts do Brasil. As bases para análise das ações de RSE têm por referência os ambientes (internos e externos); as dimensões da sustentabilidade (ambiental, sociocultural e econômica) e aos respectivos stakeholders (acionistas, clientes, funcionários, governo, meio ambiente, comunidade, fornecedores e concorrentes). A abordagem metodológica adotada para este estudo partiu de estudos de referência bibliográfica, seguida de pesquisa documental e pesquisa de campo relativa aos casos múltiplos selecionados para este estudo, com base real. Como resultado, verificou-se a complexidade de análise da territorialidade das relações sociais resultantes das ações de RSE dos resorts. Isto posto, em virtude da ausência de dados destas ações de RSE e da percepção atual dos estudos científicos sobre a territorialidade em relações sociais relativas aos resorts no Brasil. Contudo este estudo apresenta contribuições fundamentais para compreensão do poder nas relações sociais das ações de RSE dos resorts do Brasil com base na analise da matriz de responsabilidade social empresarial (MARSE).
22
Grazzini, Guilherme. « Identidade e diversidade dos pequenos mamíferos não voadores da Floresta Nacional de Piraí do Sul, Paraná, Brasil ». reponame:Repositório Institucional da UFPR, 2014. http://hdl.handle.net/1884/35205.
Texte intégralRésumé :
Resumo: Roedores e Marsupiais são mamíferos de grande importância no cenário Neotropical, possuindo elevado número de espécies e de endemismos e imprescindível papel ecológico. No estado do Paraná, até o momento são registradas 18 espécies de marsupiais e 40 de roedores. Na Floresta com Araucária por sua vez, os esforços são reduzidos, havendo ainda muito a ser feito. Este trabalho teve como objetivo conhecer as espécies desta fauna presentes na Floresta Nacional de Piraí do Sul, Paraná, contribuindo com aspectos taxonômicos, morfológicos (externos e de crânio), citogenéticos e de diversidade de cada uma delas e das principais fitofisionomias amostradas. A Unidade de Conservação está localizada na região centro-leste do estado, e possui aproximadamente 153 ha, dos quais 7,2 ha são reflorestamentos de Araucária e Imbuia, 39 ha são Pinus, 13 ha são aceiros, e cerca de 93 ha representados por formações nativas de Floresta com Araucária em diferentes estádios sucessionais. Oito fitofisionomias foram amostradas, totalizando um esforço de 5892 armadilhas.noite. Foram capturados 801 indivíduos de 16 espécies, incluindo o primeiro registro de uma espécie para a região sul do país, primeiro registro de uma espécie e um gênero para o Paraná e primeiro registro de duas espécies e um gênero para a Floresta com Araucária. Além disso, os resultados apontam para a importância de se levar em conta a complexidade e heterogeneidade ambiental e da utilização de diversos métodos de amostragem nos inventários de mastofauna de pequeno porte. Adicionalmente, as espécies Akodon montensis, Brucepattersonius iheringi, Oligoryzomys nigripes, Oxymycterus nasutus, Sooretamys angouya e Thaptomys nigrita foram mais uma vez registradas juntas em área de Floresta com Araucária. Ainda, importantes informações referentes à utilização das fitofisionomias amostradas pelas espécies capturadas foram obtidas, como por exemplo a menor diversidade encontrada em talhões de reflorestamento de Pinus elliotti em relação à Floresta com Araucária secundária, em regeneração natural. Em suma, os resultados encontrados trouxeram à tona o quanto ainda há para ser feito quando o assunto é pequenos mamíferos não voadores do Brasil meridional.
23
Mello, Claudete Regiani. « Contracepção com DIU TCu 380A : pesquisa da bacteria Neisseria Gonorrhoeae endocervical em mulheres assintomaticas : percepção da usuaria em relação a informação recebida ». reponame:Repositório Institucional da UFPR, 1996. http://hdl.handle.net/1884/35005.
Texte intégralRésumé :
Dissertação (professor titular) - Universidade Federal do Parana, Setor de Ciencias da SaudeResumo: Os objetivos do presente estudo foram pesquisar a prevalência da bacteria Neisseria gonorrhoeae endocervical em mulheres assintomáticas, usuárias de dispositivo intra-uterino TCu 380A (grupo de estudo - grupo 1) comparando com as usuárias de método anticoncepcional natural ou laqueadura tubária (grupo de controle - grupo 2) e avaliar a percepção da usuária do DIU em relação à informação recebida no serviço. O trabalho foi realizado no Setor de Anticoncepção - Disciplina de Reprodução Humana - Departamento de Tocoginecologia - Universidade Federal do Paraná, no periodo compreendido entre dezembro de 1994 até fevereiro de 1996. A pesquisa constou da avaliação de duzentas pacientes - divididas igualmente nos dois grupos - selecionados aleatoriamente durante o atendimento de rotina nos ambulatórios. O resultado, demonstrou prevalência nula da bactéria Neisseria gonorrhoeae em mulheres assintomáticas de ambos os grupos. A presença de temor de uso do DIU, desconhecimento do método e de seus fatores de risco revelou que a informação recebida foi pouca ou insuficiente para neutralizar as informações que a paciente tinha sobre o método. Sugere-se a necessidade de melhoria do relacionamento médico - paciente para modificar a visão da usuária.
Abstract: The aim of this study is to research the predominance of the endocervical bacteria Neisseria gonorrhoeae in asymptomatic women who use IUDs TCu 380A (group of study - group 1) in comparison with women using natural contraceptive method or tubal ligature (control group - group 2) and to evaluate the perception of the IUD user regarding information received at the clinic. The research was carried out at the Contraception Sector - Human Reproduction Discipline - Tocogynecology Department - Federal University of Paraná, between December of 1994 and February of 1996. The research comprised the evaluation of two hundred patients - divided equally into two groups - selected randomly during the daily routine in the outpatient care. The results showed a null predominance of the bacteria Neisseria gonorrhoeae in asymptomatic women in both groups. The fear of using IUD, the unfamiliarity with the method and its risks revealed that the information received was poor or unsatisfactory for neutralizing information the patients already had about the method. Improvements in the physician-patient relationship are needed to modify the user's point of view.
24
Al-Saedi, Hayder M. « Mathematical modelling of solid tumour growth : a Dynamical Density Functional Theory-based model ». Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/35605.
Texte intégralRésumé :
We present a theoretical framework based on an extension of Dynamical Density Functional Theory (DDFT) to describe the structure and dynamics of cells in living tissues and tumours. DDFT is a microscopic statistical mechanical theory for the time evolution of the density distribution of interacting many-particle systems. The theory accounts for cell pair-interactions, different cell types, phenotypes and cell birth and death processes (including cell division), in order to provide a biophysically consistent description of processes bridging across the scales, including the description of the tissue structure down to the level of the individual cells. Analysis of the model is presented for a single species and a two-species cases, the latter describing competition between a cancerous and healthy cells. In suitable parameter regimes, model results are consistent with biological observations. Of particular note, divergent tumour growth behaviour, mirroring metastatic and benign growth characteristics, are shown to be dependent on the cell pair-interaction parameters.
25
Ostrowski, Anna. « Generation of a novel transposon promoter probe to study gene regulation in Porphyromonas gingivalis ». Thesis, University of Leicester, 1996. http://hdl.handle.net/2381/35405.
Texte intégralRésumé :
The transposon Tn4351, originally isolated from Bacteroides fragilis, has previously been used generate many isogenic mutants in the oral pathogen Porphyromonas gingivalis. Although such transposon mutants can determine the function of putative virulence genes they can not be used to study the regulation of these genes. To correct this deficiency Tn4351 was manipulated to include a reporter gene to generate a type I promoter probe with which to study the regulation of putative virulence genes in P. gingivalis under different environmental conditions. The manipulation of Tn4351 was achieved by using PCR to amplify IS4351R, one of the two directly repeated insertion elements that flank Tn4351. The PCR primers were designed to introduce a unique restriction enzyme site at the 5' end of IS4351R into which the reporter gene, a type III chloramphenicol acetyltransferase (catIII), could be cloned. Recreation of the entire transposon was achieved by cloning a 3.8 kb AvaI fragment from Tn4351 into a unique AvaI restriction site within IS4351R::catIII creating the transposon promoter probe Tn4351::catIIl. Tn4351::catIII was cloned into the Bacteroides suicide vector pJRD215 and transferred from E. coli into P. gingivalis by an optimised filter mating procedure, which resulted in the generation of transposon inserted mutants. Southern blot analysis of these mutants confirmed that transposition of Tn4351::catIII into the P. gingivalis genome occurred randomly. Screening of the transconjugants on media supplemented with chloramphenicol identified a number of mutants containing a transcriptional fusion with the catIII gene. A quantitative assay was also used to demonstrate CAT activity in these mutants. It is hoped that Tn4351::catIII will prove to be a useful genetic tool for studying the regulation of putative virulence determinants in P. gingivalis.
26
Kioulachoglou, Anastasios C. « The ex-ante inflation corrected government balance : theory and application to ten OECD countries ». Thesis, University of Leicester, 1996. http://hdl.handle.net/2381/35505.
Texte intégralRésumé :
The thesis uses a conventional consumption function, annual data for a number of OECD countries and up-to-date precise econometric techniques to assess the extent to which consumers allow for the effects of inflation on conventional measures of income and wealth. More concretely, it uses a life cycle consumption function, which is estimated for both the long run and the short run for 10 OECD countries. For the estimation of the long run function, the Johansen approach is used. This estimation is followed by the estimation of an error collection model. The latter is accompanied by the performance of all the necessary statistical tests regarding the validity of the classical regression assumptions. In the case of a number of countries considered the wealth variable used includes series of housing wealth generated in the thesis using the perpetual inventory method. Regarding the data for the remaining variables, our effort was to use data for as many years as possible. Thus, usually the sample extents from mid-fifties to early nineties. The data sources were the OECD, the IMF, and in some cases national sources. Regarding now the estimates of the degree of income correction, the results show that the long run one exhibits considerable variation from country to country, while the short run one is generally rather low. The estimates of the short and the long run degree of income correction are used to correct the official current account government balance for the effects of inflation. The government balance as it is corrected by our approach is many times considerably different from both the conventional balance and the traditionally corrected one, while substantial are sometimes the differences between the short run and the long run estimates of this balance.
27
Plante, Jean-Sébastien Ph D. Massachusetts Institute of Technology. « Dielectric elastomer actuators for binary robotics and mechatronics ». Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35305.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
"February 2006."
Includes bibliographical references (p. 145-153).
Future robotics and mechatronics applications will require systems that are simple, robust, lightweight and inexpensive. A suggested solution for future systems is binary actuation. Binary actuation is the mechanical analogy to digital electronics, where actuators "flip" between two discrete states. Systems can be simple since low-level feedback control, sensors, wiring and electronics are virtually eliminated. However, conventional actuators, such as DC motors and gearbox are not appropriate for binary robotics because they are complex, heavy, and expensive. This thesis proposes a new actuation technology for binary robotics and mechatronics based on dielectric elastomer (DE) technology. DE actuators are a novel class of polymer actuators that have shown promising low-cost performance. These actuators were not well understood and, as a result, faced major reliability problems. Fundamental studies conducted in this thesis reveal that reliable, high performance DE actuation based on highly viscoelastic polymers can be obtained at high deformation rates, when used under fast, intermittent motion.
(cont.) Also, analytical models revealed that viscoelasticity and current leakage through the film govern performance. These results are verified by an in-depth experimental characterizion of DE actuation. A new DE actuator concept using multi-layered diamond-shaped films is proposed. Essential design tools such as reliability/performance trade-offs maps, scaling laws, and design optimization metrics are proposed. A unit binary module is created by combining DE actuators with bistable structures to provide intermittent motion in applications requiring long-duration stateholding. An application example of binary robots for medical interventions inside Magnetic Resonance Imaging (MRI) systems illustrates the technology's potential.
by Jean-Sébastien Plante.
Ph.D.
28
Bartolin, Alexandre (Alexandre Fernand Sauveur). « Offshoring is not the panacea : ensuring sustainable employment in the US manufacturing industry by leveraging demand proximity ». Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35705.
Texte intégralRésumé :
Thesis (S.M. in Transportation and S.M. in Civil and Environmental Engineering)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.Includes bibliographical references (p. 207-216).
This thesis investigates the theme of "manufacturing offshoring" that became a political issue during the 2004 U.S. presidential election. As during previous elections, employment became a key focus on the home front. Whereas the 1992 presidential election was marked by the debate around the loss of manufacturing jobs due to NAFTA, the 2004 election focused on both manufacturing and services jobs lost due to offshoring to low cost countries. For the first time, well paying jobs, such as IT programming, were outsourced to emerging countries like India or China. Offshoring of "white collar" jobs became the focus of academic, consultant, and journalist discussions in U.S., whereas offshoring of manufacturing activities generated comparatively less interest. For decades offshoring of manufacturing activities to low cost countries was used by American companies to either reduce production cost or to avoid high tariffs on exports. Offshoring strategy was historically applied in labor intensive industries, such as the apparel and electronics sectors. On the other hand, the influence of offshoring on high-tech industries was assumed to be limited. However, with the fast technological development of China and India, this paradigm might change quickly.
(cont.) This thesis explores the U.S. manufacturing sector by looking at employment and trade data at a macro-level. The terms offshoring and outsourcing will be defined and the main international trade theories discussed. The thesis develops a model to show that offshoring was only a part of the reason for the shrinkage in manufacturing employment between 1997 and 2003; the others being a drop in demand and gains in productivity. After introducing several case studies of companies in the apparel sector and the semi-conductor industry, a framework for understanding the offshoring decision process is developed. This framework defines the conditions needed to make manufacturing in U.S. competitive with production abroad. Finally through a detailed study of the expansion of the Chinese economy and the Wal-Mart phenomenon, the thesis presents the next challenges of the U.S. manufacturing sector: the birth of new competitors for high value added products and the rising constraints on price due to the pressure of retailers on manufacturers.
by Alexandre Bartolin.
S.M.in Transportation and S.M.in Civil and Environmental Engineering
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Araya, Goldberg Sergio. « Parametric constructs : computational designs for digital fabrication ». Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35505.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2006.Includes bibliographical references (leaves 150-152).
This thesis explores strategies for building design toolchains in order to design, develop and fabricate architectural forms. The hipothesys of this research is that by embedding ruled based procedures addressing generative, variational, iterative, and fabricational logics, into early phases of form finding or form research process, it is possible to enhance and augment the repertoire of possible design methods yet facilitating the development and fabrication of such designs. Shape computing, parametric modeling, scripting, and digital fabrication are the tools chained in the research presented in this thesis. Complex curved forms were chosen in the different case studies to exemplify the advantages of this method in designing and fabricating this complex shapes which have proven to be particularly difficult to construct by traditional methods, usually requiring a reduction in complexity. The method proposed here allows the designer to maintain certain level of complexity and yet explore better and more appropriate solutions.
by Sergio Araya Goldberg.
S.M.
30
Duggan, Mark G. (Mark Gregory). « Matched sampling of methods to reduce bias in an observational study ». Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35405.
Texte intégralRésumé :
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (leaves 87-91).
by Mark Gregory Duggan.
M.S.
31
Venkatesh, Sridhar Chakravarthy. « The development of a digital controller for a three-phase induction motor ». Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35005.
Texte intégralRésumé :
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (leaves 76-77).
by Sridhar Chakravarthy Venkatesh.
M.S.
32
Green, Paul Elijah. « View-dependent precomputed light transport using non-linear Gaussian function approximations ». Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/35605.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2006.Includes bibliographical references (p. 43-46).
We propose a real-time method for rendering rigid objects with complex view-dependent effects under distant all-frequency lighting. Existing precomputed light transport approaches can render rich global illumination effects, but high-frequency view-dependent effects such as sharp highlights remain a challenge. We introduce a new representation of the light transport operator based on sums of Gaussians. The non-linear parameters of the representation allow for 1) arbitrary bandwidth because scale is encoded as a direct parameter; and 2) high-quality interpolation across view and mesh triangles because we interpolate the average direction of the incoming light, thereby preventing linear cross-fading artifacts. However, fitting the precomputed light transport data to this new representation requires solving a non-linear regression problem that is more involved than traditional linear and non-linear (truncation) approximation techniques. We present a new data fitting method based on optimization that includes energy terms aimed at enforcing good interpolation. We demonstrate that our method achieves high visual quality for a small storage cost and fast rendering time.
by Paul Elijah Green.
S.M.
33
Nolan, Michael K. (Michael Kevin). « Optimal design of systems that evolve over time using neural networks ». Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/35105.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, System Design and Management Program, September 2005.Includes bibliographical references (p. 124-126).
Computational design optimization is challenging when the number of variables becomes large. One method of addressing this problem is to use pattern recognition to decrease the solution space in which the optimizer searches. Human "common sense" is used by designers to narrow the scope of search to a confined area defined by patterns conforming to likely solution candidates. However, computer-based optimization generally does not apply similar heuristics. In this thesis, a system is presented that recognizes patterns and adjusts its search for optimal solutions based on performance associations with these patterns. A design problem was selected that requires the optimization algorithm to assess designs that evolve over time. A small sensor network design is evolved into a larger sensor network design. Optimal design solutions for the small network do not necessarily lead to optimal design solutions for the larger network. Systems that are well-positioned to evolve have characteristics that distinguish themselves from systems that are not well-positioned to evolve. In this study, a neural network was able to recognize a pattern whereby flexible sensor networks evolved more successfully than less flexible networks.
(cont.) The optimizing algorithm used this pattern to select candidate systems that showed promise for successful evolution. In this limited exploratory study, a genetic algorithm assisted by a neural network achieved better performance than an unassisted genetic algorithm did. In a Pareto front analysis, the assisted genetic algorithm yielded three times the number of optimal "non-dominated" solutions as the unassisted genetic algorithm did. It realized these results in one quarter the CPU time. This thesis uses a sensor network example to establish the merit of neural network use in multi-objective system design optimization and to lay a basis for future study.
by Michael K. Nolan.
S.M.
34
Hambly, Nigel Charles. « Very low mass stars and brown dwarfs in galactic clusters ». Thesis, University of Leicester, 1991. http://hdl.handle.net/2381/35905.
Texte intégralRésumé :
This thesis describes searches for very low mass stars (0.3 > m/m > 0.08) and brown dwarfs (0.08 > m/m > 0.01) in the Pleiades and Carinae galactic open clusters using COSMOS automatic measures of Schmidt photographic plates. A broad introduction defines the problem and relates research in this area to other branches of astronomy; the second chapter presents a detailed review of the current observational and theoretical status of the subject; and the third chapter briefly describes the observational techniques employed. The results are presented in chapters four and five. The Pleiades results indicate the presence of significant numbers of very low mass stars and possible brown dwarfs with the distinct possibility of discovering more in the near future; two techniques for extracting Pleiades member stars from the field (star counts and proper motions) are described and the cluster luminosity function is found to be strikingly similar in shape to that found for the field stars near the sun. A list of probable Pleiades members, the faintest of which may be brown dwarfs, is presented in the appendix. The derived mass function, although uncertain, indicates that brown dwarfs are present in the cluster. The preliminary analysis of the field around the Carinae cluster highlights the problems of crowded field astronomy using these techniques. Although this cluster does not appear to be as rich as the Pleiades, the results obtained so far indicate possible very low mass main sequence membership that could be investigated further with more plate material. Finally, these and other results are discussed in chapter six and suggestions for further work are presented. Appendices at the end compile data on the least luminous objects known, present photoelectric calibration sequences for the plate material and reproduce reprints of two papers derived from this work.
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Jolliffe, Lee Elizabeth. « Municipal museums in Canada : contemporary directions ». Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/35305.
Texte intégralRésumé :
This thesis studies municipal museums in Canada, defined as museums owned and operated under a bylaw or directive of a municipal corporation. The objectives are to examine ideas about these museums, to document their development, to identify their operation within the local government structure, and to analyze their contemporary state. The first part identifies a tradition in which municipal museums have evolved in response to gradual increases in community support. Their organization has been related to local government structures. The middle part documents a national review which identified municipal museums and collected information on their establishment, management and operation. A survey and case studies provide statistical and documentary evidence which is presented on a national and regional basis. From these findings it has been possible to define the municipal museum population of some three hundred institutions representing approximately one quarter of all museums, identify their characteristics, explain management arrangements, outline the role of local government, describe operations, and document the status of policy development. In the final section implications of the findings are examined. Influences on museums in the areas of their role in society, the emergence of standards and patterns of support are outlined. Current developments indicate that these museums are adopting planning as a museum activity. The established identity of municipal museums is a factor which will contribute to their continuing evolution. In some regions municipal museum services may be improved and expanded through formal cooperative efforts. By identifying, documenting and analyzing the municipal museum phenomenon in Canada this work clearly establishes that these institutions are a significant and potentially unified group of museums. Supporting appendices list municipal museums by date of foundation, province, survey response and planning studies. Questionnaires, research guidelines and a select bibliography are provided.
36
Girod, Maurice. « Decision-making : a laboratory-based case study in conceptual design ». Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/35705.
Texte intégralRésumé :
The engineering design process may be seen as a series of interrelated operations that are driven by decisions: each operation is carried out as the consequence of an associated decision. Hence, an effective design process relies heavily upon effective decision-making. As a consequence, supporting decision-making may be a significant means for achieving design process improvements. This thesis concentrates on how to support selection-type decision-making in conceptual engineering design.
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Jamaludin, Roslan. « A non-conformance classification and rapid control method for improved product validation ». Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/35805.
Texte intégralRésumé :
Product quality is a topic of significant industrial importance and has been the subject of ongoing research over many years. However, the study of non-conformance reduction in the pre-production stage of product development has received only limited attention. Although products undergo chronological and rigid assessments, there are still non-conformances which are detected late in development stages particularly in pre-production. Furthermore, these non-conformances are problematic when rectification cannot be found rapidly and these problems are then carried over into production. The research, which is based on consumer electronic product, addresses product nonconformance in the pre-production. The work reported in this thesis focuses on the identification and control of non-conformances to facilitate improved product validation and aids the pre-production team in product assessment and decision making.
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Festugato, Lucas. « Comportamento de hidratação e resposta cisalhante cíclica de resíduo de mineração cimentado reforçado com fibras ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/35605.
Texte intégralRésumé :
As propriedades do solo cotidianamente podem não ser adequadas às características e às necessidades de projeto. É apresentada, como alternativa, a técnica de reforço com inclusão de elementos fibrosos à matriz de solo cimentado e não cimentado. Ainda, embora comuns, o comportamento do solo frente a solicitações cíclicas não é completamente conhecido. Nesse sentido, o estudo do comportamento de hidratação e da resposta cisalhante cíclica de um resíduo de mineração cimentado reforçado com fibras é objetivado. Para tanto, medidas de retração química, medidas de rigidez ao longo da hidratação e ensaios simple shear monotônicos e cíclicos foram realizados com resíduo de mineração cimentado e não cimentado, reforçado com fibras e não reforçado. O resíduo, oriundo da mineração de ouro, um silte arenoso com traços de argila, foi cimentado com diferentes teores de cimento Portland, entre 0% e 10% em relação à massa de solo seco, e reforçado com 0% e 0,5%, em relação à massa de sólidos secos, de fibras de polipropileno de 50mm de comprimento e 0,1mm de espessura, equivalentes a um índice aspecto de 500. Os resultados demonstraram que as fibras não afetaram o processo de hidratação das misturas de resíduo de mineração cimentadas, que apresentam tendência de atenuação logarítmica da retração química com o tempo. Quanto maiores as relações água/cimento, maior o nível de retração química. A inclusão de fibras a misturas de resíduo de mineração cimentadas, da mesma forma, não afetou a evolução dos valores de rigidez inicial, que crescem com tendência logarítmica em função do tempo e aumentam com o acréscimo do nível de cimentação. Sob condições monotônicas de cisalhamento, a adição de fibras conferiu ao material cimentado e não cimentado comportamento de endurecimento. Sob condições cíclicas de deformação cisalhante controlada, as fibras não afetaram a resposta cisalhante das amostras não cimentadas e provocaram aumento dos valores da tensão cisalhante das amostras cimentadas após sucessivos ciclos de esforços. Sob condições cíclicas de tensão cisalhante controlada, a adição de fibras às misturas não cimentadas proporcionou o aumento da resistência aos ciclos de esforços e às misturas cimentadas provocou aumento dos níveis de deformação cisalhante. A concordância das mesmas envoltórias de resistência tanto às trajetórias de tensões dos ensaios monotonônicos quanto às trajetórias dos ensaios cíclicos sob diferentes condições de carregamento possibilitou a obtenção dos mesmos parâmetros de resistência das misturas analisadas sob diferentes condições de carregamento.The soil properties commonly may not suit the project characteristics and requirements. It is presented, as alternative, the improvement technique of fibrous elements inclusion to the cemented and uncemented soil matrix. Moreover, although common, the behaviour of soil under cyclic loads is not completely known. In this sense, the study of the hydration behaviour and the cyclic shear response of fibre reinforced cemented mine tailings is the main objective of this research. Therefore, chemical shrinkage measurements, stiffness measurements during hydration and monotonic and cyclic simple shear tests were conducted on fibre reinforced and unreinforced cemented and uncemented mine tailings. The tailings, produced from gold mining, are classified as a sandy silt with traces of clay and were cemented with different amounts of Portland cement, ranging from 0% to 10% by dry weigh of soil, and reinforced with 0% and 0.5% by dry weigh of solids of polypropylene fibers 50mm long and 0.1mm thick, equivalent to an aspect ratio of 500. The results showed fibres did not affect the hydration process of cemented mine tailings mixtures, which presents logarithmic attenuation of chemical shrinkage over time. The greater the water / cement ratio, the higher the level of chemical shrinkage. The inclusion of fibers to cemented mine tailings, likewise, did not affect the evolution of initial stiffness values, that raise logarithmic over time and increase with the increase of the cementation level. Under monotonic shear conditions, the addition of fibers confers hardening behaviour to the uncemented and cemented materials. Under shear strain controlled cyclic conditions, fibres did not affect the shear response of uncemented samples and increased shear stress values of cemented samples after successive load cycles. Under shear stress controlled cyclic conditions, the fibres addition to the uncemented mixtures increased the resistance to load cycles and to the cemented mixtures increased levels of shearing strain. The agreement of the same strength envelopes to both monotonic and cyclic stress paths, under different cyclic loading conditions, allows the use of the same strength parameters of mixtures analyzed under different loading conditions.
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Jobim, Paulo Fernandes Costa. « Papel de mTOR na formação e reconsolidação da memória ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/35905.
Texte intégralRésumé :
Novas informações assimiladas pelo sistema nervoso primeiramente ficam em um estado de labilidade para depois se estabilizarem através de um processo conhecido como consolidação, que envolve síntese de proteínas. Depois da reativação, uma memória previamente consolidada retorna ao seu estado de labilidade, e para que volte a ser estável, é necessário que haja novamente síntese de proteínas. Este segundo processo é chamado de reconsolidação. Recentemente os mecanismos moleculares e celulares envolvidos na regulação da síntese protéica relacionados à formação de memória de longa duração vêm sendo esclarecidos. A proteína alvo da rapamicina em mamíferos (mTOR) modula a plasticidade sináptica pela regulação da fosforilação de dois alvos: a proteína ribossomal S6K e a proteína de ligação 4E. A amígdala basolateral e o hipocampo dorsal são parte integrante do sistema neural envolvido na formação e expressão de diversos tipos de memórias. Estudos indicam que a via de sinalização da mTOR no hipocampo tem um papel importante na consolidação da memória de ratos submetidos a tarefa de esquiva inibitória e reconhecimento de objetos e na reconsolidação da memória de medo contextual condicionado. Contudo, estudos anteriores não avaliaram o efeito da inibição de mTOR amigdalar sobre a memória de esquiva inibitória e reconhecimento de objetos. O objetivo do presente trabalho é investigar o efeito da inibição de mTOR na amígdala basolateral por rapamicina na consolidação e reconsolidação da memória de esquiva inibitória e reconhecimento de objetos e comparar estes resultados com a inibição de mTOR no hipocampo. Ratos Wistar machos foram submetidos à cirurgia estereotáxica para implantação de cânulas na amígdala basolateral e hipocampo dorsal. Os animais foram submetidos à tarefa de esquiva inibitória, um modelo animal de memória de caráter aversivo, e a tarefa de reconhecimento de objetos, um modelo animal de memória de caráter pouco aversivo. Para investigar o efeito da inibição de mTOR na consolidação e reconsolidação da memória, os animais receberam microinfusões de rapamicina intra-amigdalar e intra-hipocampal em diferentes tempos em torno do treino e do teste. Nós demonstramos que a via de sinalização de mTOR na amígdala basolateral é necessária para consolidação da memória de esquiva inibitória e de reconhecimento de objetos. Nós também mostramos que a reativação torna a memória novamente suscetível e sensível à inibição de mTOR por rapamicina.Memory formation requires protein synthesis, but only recently the cellular and molecular mechanisms involved in the regulation of protein synthesis related to the formation of long term memory has been elucidated. During memory formation, new information is acquired by the central nervous system as an initially fragile trace that over time becomes stable through a process known as consolidation. After reactivation, previously consolidated memories might return to a labile state, requiring a new round of protein synthesis to be restabilized. This second process is called reconsolidation. The basolateral amygdala and dorsal hippocampus are part of the neural systems involved in the formation and expression of several types of memory. One key regulator of protein synthesis is mTOR, a protein critical for different forms of synaptic plasticity by regulation of two targets: S6K and 4EBP. Evidence indicates that the mTOR signaling pathway in hippocampus has an important role in consolidation in rats of inhibitory avoidance and object recognition in rats, as well as in reconsolidation of contextual fear conditioning. However, previous studies have not examinated the effect of amygdalar mTOR inhibition on reconsolidation of inhibitory avoidance and object recognition. The aim of the present study was to evaluate the effect of amygdalar mTOR inhibition by rapamycin on consolidation and reconsolidation of inhibitory avoidance and object recognition, and compare the results with those obtained with hippocampal mTOR inhibition. Male rats Wistar underwent stereotaxic surgeries for cannulae implantation above the basolateral amygdala or dorsal hippocampus. After recovery, the animals were trained in inhibitory avoidance, an aversive memory task, or object recognition, a less aversive task. To investigate the effect of mTOR inhibition on memory consolidation and reconsolidation, we administered rapamycin, a specific mTOR inhibitor, into the basolateral amygdala or the dorsal hippocampus before or after training or reactivation. Our results provide evidence that mTOR in the basolateral amygdala and hippocampus might play a role in inhibitory avoidance and object recognition memory formation and reconsolidation.
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De, Serres-Bérard Thiéry. « Développement d'un modèle de peau reconstruite par génie tissulaire à partir de cellules diabétiques pour l'étude des plaies chroniques cutanées ». Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/35005.
Texte intégralRésumé :
Tableau d'honneur de la FÉSPChez les patients diabétiques, plusieurs mécanismes intervenant dans la guérison de plaies sont affectés par l’hyperglycémie. Ainsi, ils sont plus à risque de développer des ulcères chroniques présentant un haut risque d’infection et pouvant même mener à une amputation des membres inférieurs. Les recherches menées sur les fibroblastes et les kératinocytes provenant de patients diabétiques humains sont principalement effectuées avec des cultures cellulaires monocouches peu représentatives de l’environnement in vivo, ce qui empêche la découverte de traitements efficaces. Notre hypothèse propose que l’intégration de cellules diabétiques dans un modèle de peau reconstruite tridimensionnelle pourrait permettre de mieux comprendre la pathogenèse des plaies chroniques. L’objectif du projet consiste à comparer les caractéristiques de peaux reconstruites diabétiques à des peaux reconstruites saines dans deux processus importants pour la guérison de plaies, soit l’angiogenèse et la reépithélialisation. Nous avons extrait des fibroblastes, des kératinocytes et des cellules endothéliales microvasculaires à partir de biopsies de peau prélevées sur le membre amputé de patients diabétiques. Nous les avons ensuite ensemencés dans un biomatériau en chitosane et en collagène dans lequelles cellules endothéliales forment un réseau microvasculaire alors que les kératinocytes forment un épiderme stratifié. Grâce à ce modèle, nous avons observé que des cellules endothéliales saines cultivées avec des fibroblastes diabétiques formaient des réseaux microvasculaires moins développés qu’avec des fibroblastes sains. De plus, les kératinocytes diabétiques présentaient une très faible capacité de reépithélialisation suivant l’induction d’une plaie comparativement aux contrôles sains. Nous avons mis au point le premier modèle de peau reconstruite endothélialisée diabétique et démontré qu’il reproduit in vitro des caractéristiques importantes associées aux ulcères de pieds diabétiques. Ainsi, ce modèle pourra permettre de mieux comprendre les mécanismes moléculaires et cellulaires altérés par le diabète dans la guérison cutanée et servir à cribler des molécules thérapeutiques pour le traitement des plaies chroniques.
Skin wound healing is severely compromised in patients with diabetes and can lead to ulcer formation requiring lower limb amputation. Previous studies using cells derived from diabetic patients have been mostly conducted in two-dimensional monolayer cultures, which do not reproduce at all the physiology or the structure of the skin and thus limit the discovery of effective treatments. We propose that a three-dimensional reconstructed skin model made with diabetic cells could be useful to better understand the mechanisms underlying diabetic foot ulcer. Our aim was to asses the efficiency of diabetic reconstructed skin in angiogenesis and reepithelialization, which are two crucial processes of wound healing that are impaired by diabetes. We have extracted and cultured fibroblasts, keratinocytes and microvascular endothelial cells from skin biopsies taken on the amputated limb of diabetic patients. The cells were seeded on a biomaterial made of chitosan and collagen, which allowed the endothelial cells to form a capillary network and the keratinocytes to form a stratified epidermis. We have shown that coculture of healthy endothelial cells with diabetic fibroblasts in the model led to the formation of a less extensive vascular network compared to culture with healthy fibroblasts. Additionally, in diabetic reconstructed skins, keratinocytes formed a thinner epidermis with an altered histological aspect compared to healthy reconstructed skins. Following the induction of a wound in our model, diabetic keratinocytes were inefficient in achieving reepithelialization. We have developed the first endothelialized diabetic reconstructed skin, which features important characteristics found in diabetic wounds like a deficiency in the angiogenesis and reepithelialisation process. Therefore, this model could be a powerful tool to investigate the cellular and molecular mechanisms leading to chronic wounds and act as a platform to screen therapies to enhance wound healing.
41
Eddy, Grant Lee. « Study of Steady-State Wake Characteristics of Variable Angle Wedges ». Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/35205.
Texte intégralRésumé :
Current methods of creating inlet total pressure distortion for testing in gas turbine engines are only able to simulate steady-state distortion patterns. With modern military aircraft it is becoming necessary to examine the effects of transient inlet distortion on engines. One alternative being evaluated is a splitting airfoil that is essentially a wedge that can be set at different opening angles. An array of such devices would be placed in front of the engine for testing that would be capable of creating steady-state distortion patterns as well as transient distortion patterns by changing the opening angle of the airfoils.
The work here analyzes the steady-state wake characteristics of some of the splitting airfoil concepts. Single-wedge tests were conducted with various opening angles in an attempt to classify the various aspects found in the wake pattern. It was found that the wake has completely different characteristics with larger opening angles. In addition, several different combinations of wedges were also examined to see if single wedge analysis could be applied to arrays of wedges. Analysis was done on combinations of wedges aligned vertically as well as combinations that were done horizontally. It was found that single wedge characteristics change considerably when different wake patterns interact with each otherMaster of Science
42
Narayanan, Shivaram. « The Betweenness Centrality Of Biological Networks ». Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/35405.
Texte intégralRésumé :
In the last few years, large-scale experiments have generated genome-wide protein interaction networks for many organisms including Saccharomyces cerevisiae (baker's yeast), Caenorhabditis elegans (worm) and Drosophila melanogaster (fruit fly). In this thesis, we examine the vertex and edge betweenness centrality measures of these graphs. These measures capture how "central" a vertex or an edge is in the graph by considering the fraction of shortest paths that pass through that vertex or edge. Our primary observation is that the distribution of the vertex betweenness centrality follows a power law, but the distribution of the edge betweenness centrality has a Poisson-like distribution with a very sharp spike. To investigate this phenomenon, we generated random networks with degree distribution identical to those of the protein interaction networks. To our surprise, we found out that the random networks and the protein interaction networks had almost identical distribution of edge betweenness. We conjecture that the "Poisson-like" distribution of the edge betweenness centrality is the property of any graph whose degree distribution satisfies power law.Master of Science
43
Agarwal, Deepak. « An 8 GHz Ultra Wideband Transceiver Testbed ». Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/35605.
Texte intégralRésumé :
Software defined radios have the potential of changing the fundamental usage model of wireless communications devices, but the capabilities of these transceivers are often limited by the speed of the underlying processors and FPGAs. This thesis presents the digital design for an impulse-based ultra wideband communication system capable of supporting raw data rates of up to 100 MB/s. The transceiver is being developed using software/reconfigurable radio concepts and will be implemented using commercially available off-the-shelf components. The receiver uses eight 1 GHz ADCs to perform time interleaved sampling at an aggregate rate of 8 Gsamples/s. The high sampling rates present extraordinary demands on the down-conversion resources. Samples are captured by the high-speed ADC and processed using a Xilinx Virtex-II Pro (XC2VP70) FPGA. The testbed has two components: a non real-time part for data capture and signal acquisition, and a real-time part for data demodulation and signal processing. The overall objective is to demonstrate a testbed that will allow researchers to evaluate different UWB modulation, multiple access, and coding schemes. As proof-of-concept, a scaled down prototype receiver which utilized 2 ADCs and a Xilinx Virtex-II Pro (XC2VP30) FPGA was fabricated and tested.Master of Science
44
Erickson, Victoria Gillispie. « Designing for Water Quality ». Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/35105.
Texte intégralRésumé :
The following document serves as a design guidebook to assist landscape architects, designers, planners, engineers, and architects in the practice of developing land while preserving water quality. This guidebook outlines methods for maximizing permeable surfaces by providing examples of ways to minimize impervious surfaces.Master of Landscape Architecture
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Brenden, Travis Owen. « Competition Between Age-0 Largemouth Bass And Juvenile Bluegills In A Virginia Pond ». Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35705.
Texte intégralRésumé :
I assessed the potential for trophic competition between age-0 largemouth bass and juvenile bluegills by quantifying food resource use similarity in a Virginia recreational small impoundment and by experimentally stocking the species sympatrically and allopatrically in 1.0 m3 cages and monitoring mortality, growth, and resource use.
Niche breadth of bluegills in the small impoundment was greater than that of largemouth bass for eight out of nine sampling dates during the summer and fall of 1997. Virtually every type of item consumed by largemouth bass also was consumed by bluegills. In spite of this, diet overlap between the species was low. Largemouth bass fed primarily on Calanoida, Ephemeroptera, and fish, while bluegills consumed Diptera and Cyclopoida. The fishery of the impoundment consisted of relatively high and moderate densities of slow- and average-growing largemouth bass and panfish, respectively. If the fishery was managed to provide a high density of small bluegill, largemouth bass and bluegill might compete considering the number of prey items shared.
Manipulative cage experimentation, which consisted of stocking 5 largemouth bass alone, 10 bluegill alone, 5 largemouth bass and 10 bluegill, 5 largemouth bass and 30 bluegill, and 15 largemouth bass and 10 bluegill in cages, indicated that largemouth bass and bluegills can compete and that there exists a strong asymmetry in their competitive relationship. Bluegills had a much stronger impact on largemouth bass than the reverse. When stocked alone, largemouth bass grew significantly larger than when stocked with either 10 or 30 bluegills. There were no significant differences in bluegill growth rates except between bluegills stocked alone and bluegills stocked with 15 largemouth bass. The analysis of food resource use indicates that Copepoda and Diptera larvae may be the limiting resources catalyzing the competitive interaction.
This research suggests that a competitive juvenile bottleneck could occur, depending largely on whether overwinter survival of largemouth bass is size related. Competition between largemouth bass and bluegills may explain why enhancement stocking of fingerling largemouth bass typically is not successful. Further research is needed on the appropriate timing and length at stocking of introductory largemouth bass stockings. Additionally, I recommend that resource partitioning and competition between largemouth bass and bluegills be explored in connection with studies concerning overwinter survival and angling opportunities in small impoundments. Competition between the species may impose an ecological constraint that restricts achievable options in certain systems.
Master of Science
46
Holland, Michelle Leigh. « Stiffener Design for Beam-to-Column Connections ». Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35305.
Texte intégralRésumé :
Stiffeners are used as a means of providing additional support to columns at beam connection locations. They are added when the strength of the column is exceeded but full moment strength of the beam section is desired. In determining the design of column stiffeners, there are no specifications for determining the distribution of load between the column web and stiffeners. The AISC Load and Resistance Factor Design Specifications provides guidelines for determining the stiffener area but no specifications are given. The actual loads taken by the stiffener and web are therefore not truly known.
In this study, experiments were done to determine the load supported by the stiffeners and web when tensile forces are applied to the specimen. The initial stiffener design for the test specimens was based on LRFD guidelines. The actual load distribution between the column web and stiffeners is determined from strain data obtained during testing. This distribution is compared with the assumed loads obtained from the initial LRFD calculations. Finite element analysis is also utilized to confirm the consistency of the results obtained from the experiments. Using this information, a new method is developed which better predicts the distribution of load between the column web and the stiffener.Master of Science
47
Popritkin, Gilda Padilla. « To Build Upon Ruin ». Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/35505.
Texte intégralRésumé :
it is essential to regard the history of a site. to find the complexities that to others have mattered. architecture has a responsibility to interpret the past to future generations. it is then that it becomes immortal.Master of Architecture
48
Bendfeldt, Eric S. « Dynamics and Characterization of Soil Organic Matter on Mine Soils 16 Years after Amendment with Topsoil, Sawdust, and Sewage Sludge ». Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35805.
Texte intégralRésumé :
The present state and future prospect of the world's soil resources has prompted scientists and researchers to address the issue of soil quality and sustainable land management. Soil quality research has focused on intensively-managed agricultural and forest soils, but the concept and importance of soil quality is also pertinent to disturbed systems such as reclaimed mine soils. The restoration of soil function and mine soil quality is essential to long-term ecosystem stability. The objectives of this study were (i) to determine the comparative ability of topsoil, sawdust, and sewage sludge amendments, after 16 years, to positively affect mine soil quality using the following key soil quality variables: organic matter content, aggregate stability, and mineralizable nitrogen, (ii) to determine the effects of these key soil quality variables on plant productivity, and (iii) to determine the comparative ability of trees and herbaceous plants to persist and to conserve or maintain mine soil quality. In 1982, a mined site was amended with seven different surface treatments: a fertilized control (2:1 sandstone:siltstone), 30 cm of native soil + 7.8 Mg ha-1 lime, 112 Mg ha-1 sawdust, and municipal sewage sludge (SS) at rates of 22, 56, 112, and 224 Mg ha-1. Four replicates of each treatment were installed as a randomized complete block design. Whole plots were split according to vegetation type: pitch x loblolly pine hybrid (Pinus rigida x taeda) trees and Kentucky-31 tall fescue (Festuca arundinacea Schreb.). Soil analyses of composite samples for 1982, 1987, and 1998 were evaluated for changing levels of mine soil quality. The positive effect of these organic amendments on organic matter content, total nitrogen, and other soil parameters was most apparent and pronounced after 5 growing seasons. However, after 16 years, soil organic matter content and total nitrogen appear to be equilibrating at about 4.3 and 1.5%. There was a significant difference in organic matter content and nitrogen mineralization potential between vegetation types. Organic matter inputs by vegetation alone over the 16-yr period in the control plots resulted in organic matter and nitrogen mineralization potential values comparable to levels in the organically amended plots. The results suggest that about 15 years is needed for climate, moisture availability, and other edaphic features to have the same influence on overall organic matter decomposition, N accretion, organic nitrogen mineralization levels, system equilibrium, and overall mine soil quality as a one-time 100-Mg ha-1 application of organic amendment. Tree volume and biomass were measured as indices of the effects of organic matter content 16 years after initial amendment. Individual tree volumes of the sawdust, 22, 56, and 112 Mg ha -1 SS treatments retained 18 to 26% more volume than the control, respectively. Overall, fescue production was the same among treatments. Organic amendments improved initial soil fertility for fescue establishment, but it appears that they will have little or no long-lasting effect on plant productivity.Master of Science
49
Gao, Yu. « Calibration and Comparison of the VISSIM and INTEGRATION Microscopic Traffic Simulation Models ». Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/35005.
Texte intégralRésumé :
Microscopic traffic simulation software have gained significant popularity and are widely used both in industry and research mainly because of the ability of these tools to reflect the dynamic nature of the transportation system in a stochastic fashion. To better utilize these software, it is necessary to understand the underlying logic and differences between them. A Car-following model is the core of every microscopic traffic simulation software. In the context of this research, the thesis develops procedures for calibrating the steady-state car-following models in a number of well known microscopic traffic simulation software including: CORSIM, AIMSUN, VISSIM, PARAMICS and INTEGRATION and then compares the VISSIM and INTEGRATION software for the modeling of traffic signalized approaches.
The thesis presents two papers. The first paper develops procedures for calibrating the steady-state component of various car-following models using macroscopic loop detector data. The calibration procedures are developed for a number of commercially available microscopic traffic simulation software, including: CORSIM, AIMSUN2, VISSIM, Paramics, and INTEGRATION. The procedures are then applied to a sample dataset for illustration purposes. The paper then compares the various steady-state car-following formulations and concludes that the Gipps and Van Aerde steady-state car-following models provide the highest level of flexibility in capturing different driver and roadway characteristics. However, the Van Aerde model, unlike the Gipps model, is a single-regime model and thus is easier to calibrate given that it does not require the segmentation of data into two regimes. The paper finally proposes that the car-following parameters within traffic simulation software be link-specific as opposed to the current practice of coding network-wide parameters. The use of link-specific parameters will offer the opportunity to capture unique roadway characteristics and reflect roadway capacity differences across different roadways.
Second, the study compares the logic used in both the VISSIM and INTEGRATION software, applies the software to some simple networks to highlight some of the differences/similarities in modeling traffic, and compares the various measures of effectiveness derived from the models. The study demonstrates that both the VISSIM and INTEGRATION software incorporate a psycho-physical car-following model which accounts for vehicle acceleration constraints. The INTEGRATION software, however uses a physical vehicle dynamics model while the VISSIM software requires the user to input a vehicle-specific speed-acceleration kinematics model. The use of a vehicle dynamics model has the advantage of allowing the model to account for the impact of roadway grades, pavement surface type, pavement surface condition, and type of vehicle tires on vehicle acceleration behavior. Both models capture a driverâ s willingness to run a yellow light if conditions warrant it. The VISSIM software incorporates a statistical stop/go probability model while current development of the INTEGRATION software includes a behavioral model as opposed to a statistical model for modeling driver stop/go decisions. Both software capture the loss in capacity associated with queue discharge using acceleration constraints. The losses produced by the INTEGRATION model are more consistent with field data (7% reduction in capacity). Both software demonstrate that the capacity loss is recovered as vehicles move downstream of the capacity bottleneck. With regards to fuel consumption and emission estimation the INTEGRATION software, unlike the VISSIM software, incorporates a microscopic model that captures transient vehicle effects on fuel consumption and emission rates.Master of Science
50
Fronk, Ryan. « Dual-side etched microstructured semiconductor neutron detectors ». Diss., Kansas State University, 2017. http://hdl.handle.net/2097/35405.
Texte intégralRésumé :
Doctor of PhilosophyDepartment of Mechanical and Nuclear Engineering
Douglas S. McGregor
Interest in high-efficiency replacements for thin-film-coated thermal neutron detectors led to the development of single-sided microstructured semiconductor neutron detectors (MSNDs). MSNDs are designed with micro-sized trench structures that are etched into a vertically-oriented pvn-junction diode, and backfilled with a neutron converting material, such as 6LiF. Neutrons absorbed by the converting material produce a pair of charged-particle reaction products that can be measured by the diode substrate. MSNDs have higher neutron-absorption and reaction-product counting efficiencies than their thin-film-coated counterparts, resulting in up to a 10x increase in intrinsic thermal neutron detection efficiency. The detection efficiency for a single-sided MSND is reduced by neutron streaming paths between the conversion-material filled regions that consequently allow neutrons to pass undetected through the detector. Previously, the highest reported intrinsic thermal neutron detection efficiency for a single MSND was approximately 30%. Methods for double-stacking and aligning MSNDs to reduce neutron streaming produced devices with an intrinsic thermal neutron detection efficiency of 42%. Presented here is a new type of MSND that features a complementary second set of trenches that are etched into the back-side of the detector substrate. These dual-sided microstructured semiconductor neutron detectors (DS-MSNDs) have the ability to absorb and detect neutrons that stream through the front-side, effectively doubling the detection efficiency of a single-sided device. DS-MSND sensors are theoretically capable of achieving greater than 80% intrinsic thermal neutron detection efficiency for a 1-mm thick device. Prototype DS-MSNDs with diffused pvp-junction operated at 0-V applied bias have achieved 53.54±0.61%, exceeding that of the single-sided MSNDs and double-stacked MSNDs to represent a new record for detection efficiency for such solid-state devices.