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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Lateralized Induction of Cardiovascular Responses: Exploring Asymmetric Autonomic Regulation

Mcginley, Jared Joseph 13 June 2012 (has links)
There is clear evidence that the autonomic nervous system (ANS) is lateralized at both the peripheral as well as the central levels of the nervous system. Both the vagus and the sympathetic ganglia asymmetrically innervate the sino-atrial node and the myocardium of the heart. This lateralization has also been observed in afferent as well as efferent projections to nuclei in the brainstem, hypothalamus, and amygdala. Where laterality has not been as clear is in regions of the frontal lobe dedicated to the regulation of autonomic nervous system responses. This study addressed that issue via the implementation of lateralized autonomic response-evoking tasks. With the use of cardiovascular and electrodermal measures, the present study indexed autonomic responses to lateralized stimuli. This study also explored the role of lateralization within sex as well as in relation to reported gender identity. The findings lend support to the right hemisphere as serving a dominant role in regulating sympathetic nervous system activity, while lending less conclusive support for lateralization of parasympathetic nervous system regulation. Men demonstrated greater lateralization for sympathetic nervous system responses across several different metrics of autonomic indices. The exploration of gender variables in relation to lateralization of autonomic responses was generally not supported. / Master of Science
122

IgM and Complement in Regulation of Antibody Responses

Sörman, Anna January 2015 (has links)
Animals deficient in complement components C1q, C4, C3, and CR1/2 have severely impaired antibody responses. C1q is primarily activated by antibody-antigen complexes. Antigen-specific IgM in complex with an antigen is able to enhance the antibody response against that antigen. This is dependent on the ability of IgM to activate complement. Naïve mice have very low amounts of specific antibodies and therefore it is surprising that classical pathway activation plays a role for primary antibody responses. It was hypothesized that natural IgM, present in naïve mice, would bind an antigen with enough affinity to activate C1q. To test this, a knock-in mouse strain, Cm13, with a point mutation in m heavy chain, making its IgM unable to activate complement was constructed. Surprisingly, the antibody responses in Cm13 were normal. Puzzled by the finding that the ability of IgM to activate complement was required only for some effects, the immunization protocol was changed to mimic an infectious scenario. With this regime, Cm13 mice had an impaired antibody response compared to wildtype (WT) mice. The antibody response in WT mice to these repeated low-dose immunizations was also enhanced. These observations suggest that IgM-mediated enhancement indeed plays a physiological role in initiation of early antibody responses. IgM-mediated enhancement cannot however compensate for the dependecy of T-cell help. Although IgM from WT mice enhanced the antibody response, the T-cell response was not enhanced. The connection between classical pathway activation and CR1/2 is thought to be generation of ligands for CR1/2. In mice, CR1/2 are expressed on B cells and follicular dendritic cells (FDC). Although CR1/2 are crucial for a normal antibody response, the molecular mechanism(s) are not understood. To investigate whether CR1/2 must be expressed on B-cells or FDC to generate a normal antibody response, chimeric mice between WT and CR1/2-deficient mice were constructed. The results show that CR1/2+ FDC were crucial for the generation of antibody responses. In the presence of CR1/2+ FDC, both CR1/2+ and CR1/2- B cells were equally good antibody producers. However, for an optimally enhanced antibody response against IgM-antigen complexes, both B cells and FDC needed to express CR1/2.
123

Immunity to Chlamydia trachomatis and Host-Pathogen Interactions During Infection

Olive, Andrew James 25 February 2014 (has links)
Infections with the bacterial pathogen Chlamydia trachomatis are a critical public health problem. Chlamydia remains the number one cause of preventable blindness worldwide and the leading cause of bacterial sexually transmitted infections in the United States. In humans, repeat and persistent infections with Chlamydia result in severe inflammation. Inflammation in the conjunctiva can result in blindness, while inflammation in the genital tract can result in pelvic inflammatory disease, ectopic pregnancy or infertility. In order to curb the increasing incidence of Chlamydia infections worldwide it will be necessary to develop a protective vaccine that affords long-term protection and prevents pathologies. To better inform vaccine development we must understand the mechanisms that drive long-term immunity in the genital tract and elucidate critical interactions between Chlamydia and host cells to uncover potential mechanisms of immune evasion.
124

A population gain control model of spatiotemporal responses in the visual cortex

Sit, Yiu Fai 22 March 2011 (has links)
The mammalian brain is a complex computing system that contains billions of neurons and trillions of connections. Is there a general principle that governs the processing in such large neural populations? This dissertation attempts to address this question using computational modeling and quantitative analysis of direct physiological measurements of large neural populations in the monkey primary visual cortex (V1). First, the complete spatiotemporal dynamics of V1 responses over the entire region that is activated by small stationary stimuli are characterized quantitatively. The dynamics of the responses are found to be systematic but complex. Importantly, they are inconsistent with many popular computational models of neural processing. Second, a simple population gain control (PGC) model that can account for these complex response properties is proposed for the small stationary stimuli. The PGC model is then used to predict the responses to stimuli composed of two elements and stimuli that move at a constant speed. The predictions of the model are consistent with the measured responses in V1 for both stimuli. PGC is the first model that can account for the complete spatiotemporal dynamics of V1 population responses for different types of stimuli, suggesting that gain control is a general mechanism of neural processing. / text
125

Categorical Responses in Mixture Experiments

January 2016 (has links)
abstract: Mixture experiments are useful when the interest is in determining how changes in the proportion of an experimental component affects the response. This research focuses on the modeling and design of mixture experiments when the response is categorical namely, binary and ordinal. Data from mixture experiments is characterized by the perfect collinearity of the experimental components, resulting in model matrices that are singular and inestimable under likelihood estimation procedures. To alleviate problems with estimation, this research proposes the reparameterization of two nonlinear models for ordinal data -- the proportional-odds model with a logistic link and the stereotype model. A study involving subjective ordinal responses from a mixture experiment demonstrates that the stereotype model reveals useful information about the relationship between mixture components and the ordinality of the response, which the proportional-odds fails to detect. The second half of this research deals with the construction of exact D-optimal designs for binary and ordinal responses. For both types, the base models fall under the class of Generalized Linear Models (GLMs) with a logistic link. First, the properties of the exact D-optimal mixture designs for binary responses are investigated. It will be shown that standard mixture designs and designs proposed for normal-theory responses are poor surrogates for the true D-optimal designs. In contrast with the D-optimal designs for normal-theory responses which locate support points at the boundaries of the mixture region, exact D-optimal designs for GLMs tend to locate support points at regions of uncertainties. Alternate D-optimal designs for binary responses with high D-efficiencies are proposed by utilizing information about these regions. The Mixture Exchange Algorithm (MEA), a search heuristic tailored to the construction of efficient mixture designs with GLM-type responses, is proposed. MEA introduces a new and efficient updating formula that lessens the computational expense of calculating the D-criterion for multi-categorical response systems, such as ordinal response models. MEA computationally outperforms comparable search heuristics by several orders of magnitude. Further, its computational expense increases at a slower rate of growth with increasing problem size. Finally, local and robust D-optimal designs for ordinal-response mixture systems are constructed using MEA, investigated, and shown to have high D-efficiency performance. / Dissertation/Thesis / Doctoral Dissertation Industrial Engineering 2016
126

Teacher Attention as a Controlling Influence of Of Student Classroom Behavior

Smith, LaGrande E. 01 May 1977 (has links)
The purpose of this thesis was to assess the influence of the teachers' classroom behavior on students' classroom behavior. Three hypotheses were made as the teacher systematically increases positive responses and decreases negative responses in the classroom, 1) the total time spent with the misbehaving student will decrease, 2) student non-attentive behavior will decrease and student attentive behavior will increase, and 3) there will be an inverse relationship between teacher negative responses and student attentive behavior. Student subjects were selected randomly from a previously selected group of misbehaving students; teacher subjects were 12 volunteers from a Junior High School who wanted to learn more about classroom behavior management. During the treatment process, teachers were to attempt to 1) decrease the amount of teacher negative reaction, 2) increase the amount of teacher positive response, and 3) to implement the various types of methods, procedures, and principles learned in the training course. Six trained observers were used to collect data over a 3-month period. A baseline of classroom behavior was established while the teachers were simultaneously involved in a classroom behavior management training course. Both student and teacher behaviors were computed and graphed on a logarithmic graph. All three hypotheses were confirmed at or beyond the .05 level of significance. Results were discussed in terms of the relationships that exist between the variables, and how they apply to the hypotheses.
127

Mining extraction in the ocean depths: a baseline to understand and reduce acoustic impact on biodiversity

Mauro, Manuela 23 March 2021 (has links)
Tesis por compendio / [ES] A lo largo de la historia, el hombre ha explotado los recursos minerales de la tierra para su supervivencia y desarrollo tecnológico sin un equilibrio con su regeneración. Dado el crecimiento de la población mundial y la reducción de recursos, el hombre comenzó a buscar nuevos depósitos que se encontraron en la década de 1960 en las profundidades de los océanos. Con estos, la humanidad empezò a pensar en extraer los minerales de estos depósitos y esto llevò al nacimiento de Deep Sea Mining (DSM). Las consecuencias de las actividades mineras en las profundidades del mar no se conocen realmente y los efectos pueden ser diferentes: contaminación acústica, contaminación lumínica, contaminación química, destrucción del hábitat, fragmentación del hábitat y pérdida de especies que son la base de muchos sistemas vitales. El impacto acústico de estas actividades puede tener importantes consecuencias en las especies marinas, aunque este es el tema más ignorado. El propósito de este proyecto de doctorado fue proporcionar una comprensión básica de los posibles impactos acústicos del DSM en la biodiversidad antes de que comiencen estas actividades. Para hacer esto, el proyecto de doctorado se organizó en varios pasos. Primero, durante un experimento indoor, se analizaron las respuestas bioquímicas en invertebrados sometidos a estrés acústico, Arbacia lixula y Mytilus galloprovincialis. Los resultados demostraron efectos significativos en la actividad de citotoxicidad, expresión de heat shock protein (HSPs) y actividades enzimáticas (esterasas, fosfatasas alcalinas, peroxidasas) en el líquido celomático de los erizos de mar sometidos a estrés acústico. También se observaron efectos significativos en el nivel de glucosa, la citotoxicidad y las actividades enzimáticas (esterasa, fosfatasa alcalina, peroxidasa) de la glándula digestiva del mejillón. En segundo lugar, se analizaron las respuestas bioquímicas de vertebrados e invertebrados sometidos in-situ a la emisión de watergun: Chromis chromis, Holothuria tubulosa y Arbacia lixula. Se encontraron efectos significativos sobre los niveles de cortisol en peces y las actividades enzimáticas (esterasas, fosfatasas alcalinas, peroxidasas y superoxide dismutasas) en membrana peristomial de erizo de mar. Además, las respuestas bioquímicas enzimáticas analizadas en los fluidos celómicos de los equinodermos fue significativa solo por A. lixula y solo en la activade peroxidasica. Tercero se estudiaron los cambios de comportamiento en las condiciones experimentales en juveniles de Sparus aurata sometidos a 4 frecuencias de emisión acústica diferentes. Este experimento demostró que solo las bajas frecuencias tuvieron efectos en todas las respuestas comportamental: altura de natación, motilidad y dispersión del grupo. Sobre la base de los datos de comportamiento obtenidos in vivo en peces jóvenes, se creó un modelo numérico para predecir los impactos de diferentes frecuencias de emisión acústica. Utilizando los resultados obtenidos y la bibliografía científica, se propuso un primer estándar técnico que es útil para la minería. / [CA] A lo llarc de l'historia, l'home ha explotat els recursos minerals de la terra per a la seua supervivencia i desenroll tecnologic sense un equilibri en la seua regeneracio. Donat el creiximent de la poblacio mundial i la reduccio de recursos, l'home escomençà a buscar nous deposits que se trobaren en la decada de 1960 en les fondaries dels oceans. En estos, l'humanitat empezò a pensar en extraure els minerals d'estos deposits i aço llevò al naiximent de Deep Sea Mining (DSM). Les conseqüencies de les activitats mineres en les fondaries del mar no se coneixen realment i els efectes poden ser diferents: contaminacio acustica, contaminacio lluminica, contaminacio quimica, destruccio de l'habitat, fragmentacio de l'habitat i perdua d'especies que son la base de molts sistemes vitals. L'impacte acustic d'estes activitats pot tindre importants conseqüencies en les especies marines, encara que este es el tema mes ignorat. El proposit d'este proyecte de doctorat fon proporcionar una comprensio basica dels possibles impactes acustics del DSM en la biodiversidad abans de que escomencen estes activitats. Per a fer aço, el proyecte de doctorat s'organisà en varis passos. Primer, durant un experiment indoor, s'analisaren les respostes bioquimiques en invertebrats somesos a estrés acustic, Arbacia lixula i Mytilus galloprovincialis. Els resultats demostraren efectes significatius en l'activitat de citotoxicidad, expressio d'heat shock protein (HSPS) i activitats enzimáticas (esterasa, fosfatasas alcalina, peroxidasas) en el liquit celomático dels capellanets de mar somesos a estrés acustic. Tambe s'observaren efectes significatius en el nivell de glucosa, la citotoxicidad i les activitats enzimáticas (esterasa, fosfatasa alcalina, peroxidasas) de la glandula digestiva de la clochina. En segon lloc, s'analisaren les respostes bioquimiques de vertebrats i invertebrats somesos in-situ a l'emissio de watergun: Chromis chromis, Holothuria tubulosa i Arbacia lixula. se trobaren efectes significatius sobre els nivells de cortisol en peixos i les activitats enzimáticas (esterasas, fosfatasas alcalines, peroxidasas y superoxide dimutases) en peristomes de capellanet de mar. Ademes, les respostes bioquimiques enzimáticas analisades en els decorreguts celómicos dels equinoderms fon significativa nomes per A. lixula i nomes en l'activade peroxidasica. Tercer s'estudiaren els canvis de comportament en les condicions experimentals en jovenils de Sparus aurata somesos a 4 freqüencies d'emissio acustica diferents. Este experiment demostrà que nomes les baixes freqüencies tingueren efectes en totes les respostes comportamental: alçada de natacio, motilidad i escampada del grup. Sobre la base de les senyes de comportament obtinguts in vivo en peixos jovens, se creó un model numeric per a predecir els impactes de diferents freqüencies d'emissio acustica. Utilisant els resultats obtinguts i la bibliografia cientifica, se propongue un primer estandart tecnic que es util per a la mineria. / [EN] Throughout history, man has exploited the earth's mineral resources for its survival and for technological development without regard for their regeneration. Given the growth of the world population and given the fall in resources, man started looking for new deposits, which were found in 1960s in the ocean depths. Humankind then began to consider extracting minerals from these deposits and this gave origin to Deep Sea Mining (DSM). The consequences of mining activities in the deep sea are not entirely known and the effects can be varied: noise pollution, light pollution, chemical pollution, habitat destruction, habitat fragmentation and the loss of species which we consider the basis of many life systems. The acoustic impact of these activities could have significant consequences on marine species; nevertheless, this has been the most overlooked issue to date. The aim of this PhD project was to provide baseline knowledge of possible acoustic impacts of DSM on biodiversity before mining begins. In order to do this, the PhD project was organised into 3 different stages. First, during an indoor experiment, the biochemical responses of invertebrates Arbacia lixula and Mytilus galloprovincialis subjected to acoustic stress were analysed. The results showed significant changes in cytotoxicity activity, expression of heat shock proteins (HSPs), and enzyme activities (esterases, alkaline phosphatases, peroxidases) in the coelomic fluid of sea urchins subjected to acoustic stress. Significant effects were also observed in glucose levels, cytotoxicity and enzyme activities (esterase, alkaline phosphatase, peroxidase) in the digestive gland of the mussel. Second, the biochemical responses of vertebrates and invertebrates subjected in-situ to watergun emission were analysed: Chromis chromis, Holothuria tubulosa and Arbacia lixula. Significant effects on fish cortisol levels and on enzyme activities in sea urchin peristomes were found. Furthermore, the enzyme biochemical responses analysed in the coelomic fluids of echinoderms showed significant effects only in A. lixula sea urchin and only in peroxidase activity. Third, behavioural changes in experimental conditions were studied in juveniles of Sparus aurata subjected to 4 different acoustic emission frequencies. This experiment showed that only low frequencies had effects on all the behavioural responses analysed: swimming height, motility and dispersion of the group. Based on behavioural data obtained in vivo on juvenile fish, a numerical model was created to predict the impacts of different acoustic emission frequencies. Using the results obtained and literature, a first technical standard useful for mining activities was drawn up. / The study of the Section 3.3 was supported by grants from MIUR (Ministry of Education, University and Research), Fondo Finalizzato alla Ricerca di Ateneo (FFR, 2018-2021) to M.V. and by the CNR research project: IMPLEMENTATION OF THE SOS CONVENTION - Offshore Platforms & Impacts between MATTM and CNR-DTA, (Capo Granitola, Campobello di Mazara) Work Package E: Indepth technical and scientific evaluation of the effects on marine ecosystems of airgun technologies and the effects of a watergun The study of the Section 3.4 study was conducted in the framework of the PhD program in Mediterranean Biodiversity XXXII cycle (International) of the University of Palermo. I. Perez-Arjona, M. Bou-Cabo and V. Espinosa acknowledge the financial support of the European Comission -project 11.0661/2018794607/SUB/ENV.C2. Risk-based Approaches to Good Environmental Status (RAGES). The other founding supports come from PhD Innovative with Industrial Characterization PON 2014-2020 and the projects CAIMAR Joint Laboratory Italy-Argentina (Laboratori Congiunti Bilaterali Internazionali of the Italian National Reseach Council, 2017-2019) and BOSS – Study of bioacoustics and applications for the sustainable exploitation of marine resources (Projects of major importance in the Scientific and Technological Collaboration Executive Programmes, funded by the Italian Ministry of Foreign Affairs and International Cooperation). / Mauro, M. (2020). Mining extraction in the ocean depths: a baseline to understand and reduce acoustic impact on biodiversity [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/144131 / TESIS / Compendio
128

The effects of livestock grazing on semi-natural grassland communities along an elevational gradient in Norway

Petrauskaitė, Ieva January 2020 (has links)
Moderate livestock grazing is often identified as a useful management tool for sustaining biodiverse grassland communities and has long been practiced in Scandinavian mountains. Despite of a growing number of studies focusing on grazing effects along elevational gradients worldwide, there is still limited knowledge of how grazing intensity varies over time and how it affects plant communities on species and functional group level. Moreover, the majority of existing studies are conducted in enclosures with controlled stocking rate, while free-range grazing with a highly varied livestock number is the common practise in Scandinavia. Therefore, the aim of this study was to quantify free-range grazing intensity over the growing season along an elevational gradient and to evaluate how grazing affects plant communities on species, functional group and community level. In order to quantify grazing intensity, we conducted a grazer exclusion experiment along an elevational gradient in Norway in the growing season of 2019. We quantified grazing intensity as the difference in dry above-ground biomass between grazed and caged plots and analyzed plant composition on community and functional group level as well as recorded species-specific grazing damage and potentially influential abiotic factors. To capture the effects of temporal variation in grazing we also relocated caged and grazed plots in four-week intervals during the growing season. We demonstrated that grazing intensity gradually decreased with elevation and elevation explained 77% of the variation in grazing among sites. Lower grazing intensity at high elevation is likely related to decreasing plant productivity and differences in plant community composition along the gradient. Grazers reduced the biomass of graminoids and forbs in the intensively grazed lower sites. Grazing damage varied among sites for five of the eight most commonly grazed plant species, which was mainly driven by a higher grazing damage in the intermediate site (900m a.s.l.). Selective grazing was observed in three sheep-dominated study sites. Grazing intensity did not significantly vary during the growing season at any site, possibly due to weak temporal effects of an overall short growing season. In accordance with other studies, we demonstrated that grazing homogenized plant community composition in actively grazed sites that were relatively species rich. To conclude, livestock grazing can help maintain biodiverse semi-natural grasslands, yet when grazing is applied as a management tool in the mountainous landscapes, we suggest considering that grazing intensity, and therefore its effects, will vary with elevation.
129

Cardiovascular and Hormonal Responses to Orthostasis Following Four Hours of Head-Down Rest in Endurance-Exercise-Trained and Untrained Subjects

Chen, Jia-Jen 12 1900 (has links)
Cardiovascular and hormonal responses to +700 head-up tilt (HUT: orthostatic challenge) were compared between six endurance exercise trained (ET) and six untrained (UT) subjects prior to and immediately following 4 hours of -60 head-down rest (HDR). The ET subjects showed a significant (P < 0.05) decrease in orthostatic tolerance time (pre syncopal symptoms) during post-HDR HUT, while no difference was observed between ET and UT groups in pre-HDR HUT. The volume regulatory hormonal responses were similar between ET and UT groups whether during HUT or HDR. The pre-syncopal subjects had a greater increase in plasma arginine vasopressin and less increase in plasma renin activity and plasma aldosterone during HUT than was observed in non syncopal subjects. These data suggest that HDR deconditioning was more effective in the ET subjects.
130

Antigen Presenting Cells-Mediated Innate and Adaptive Immune Responses to Live Attenuated Edwardsiella Ictaluri Vaccines in Channel Catfish

Kordon, Adef 10 August 2018 (has links)
Vaccination against intracellular pathogens requires generation of pool of memory T cells, which can respond upon infection and mediate immune responses by either killing of infected host cells or induce killing mechanisms in infected cells. T cell-inducing vaccines aim to deliver the antigen to antigen presenting cells (APCs) by presenting on MHC molecules thus bridging innate and adaptive immunity. The intracellular pathogen Edwardsiella ictaluri causes enteric septicemia of catfish (ESC), which is a devastating disease in catfish industry. E. ictaluri can survive in professional phagocytes and use them as an infection source. Two new live attenuated vaccine (LAV) strains, EiDELTAevpB and ESC-NDKL, were developed by our group. However, the role of LAVs in phagocytosis, bacterial killing, and antigen presentation is unexplored. Therefore, further research is necessary to determine immune responses in channel catfish against LAVs. The long-term goal of this project is to identify immunological APC-dependent mechanisms that underscore E. ictaluri pathogenesis to enable development of effective control strategies for ESC. The overall goal of this project is to assess the role of three professional APCs, dendritic cells (DCs), macrophages and B cells in the LAV-induced innate and adaptive immune responses in catfish. The central hypothesis is that efficacious LAV strains will enhance phagocytosis and microbial killing, and promote the generation of T cells that regulate and control protective B cell-mediated immunity. The rationale for this research is that more detailed knowledge about phenotype and function of catfish APCs will not only help gain insight into the evolution of vertebrate adaptive immune system but will provide valuable information for development and optimization of immunotherapies and vaccination protocols for aquaculture use. In this study, we first identified DC-like cells in immune-related organs of catfish and assessed their expression patterns in lymphoid organs of catfish in E. ictaluri infection. Although WT strain induces the functional inability of DC-like cells in migration and maturation, LAVs strains promote the migration and maturation of DC-like cells for antigen presentation. Two LAVs enhanced the phagocytosis and killing activity in catfish macrophages and B cells. Also, LAVs induce high expression of T cell-related genes without causing inflammation.

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