• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 8
  • 4
  • 2
  • 1
  • 1
  • Tagged with
  • 17
  • 17
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
11

Improving the cost-effectiveness of water wave measurements and understanding of its impact on natural and restored marsh communities

Temple, Nigel 30 April 2021 (has links)
Coastal restoration has become a necessary and ubiquitous practice to enhance and conserve the many ecosystem services lost by marsh degradation. Wave climate is one of the most critical factors to consider for restoration projects. However, knowledge of the ways that waves affect marsh plants and the ecosystem services they provide is limited. The purpose of my dissertation was to improve the effectiveness of coastal marsh restoration by addressing the limitations and gaps associated with plant and ecosystem responses to waves through empirical research with three primary goals: 1) develop and test a low-cost wave gauge, 2) use it to compare above- and below-ground plant growth responses along a wave climate gradient, and 3) evaluate the effects of waves on nutrient removal in constructed marshes. I used three field and laboratory experiments to accomplish these goals. The low-cost wave gauge was developed using an Arduino microcontroller and various accessories. After development, the gauge was evaluated against a commercial gauge in a series of laboratory and field tests. Comparisons revealed over 90% agreement between the gauges and confirmed the applicability of the low-cost gauge. A total of thirty gauges were then constructed and deployed at sites within Mobile Bay, Alabama and surrounding tributaries. In addition to wave energy, plant data was also collected at each site, including above- and below-ground biomass, shoot density, height, and diameter. These data suggested that waves affect plant growth responses in ways not explained by the current plant response paradigm. For example, while greater diameter shoots best attenuate waves, shoot diameter declined with greater wave exposure in this study. This response was common among the study species. Other plant responses were species-specific. Finally, a field experiment was constructed to examine the main and interactive effects of sediment type, initial planting density, platform slope, and platform position at sites exposed to and protected from waves. Results from this experiment suggested that waves may potentially mitigate the effective removal potential of constructed marshes. Taken together, this dissertation advances research on plant responses to waves and provides new tools for land managers working on coastal restoration and conservation projects.
12

Relations among Involuntary Stress Responses, Social Support, and Cortisol Output during Acute Social Stress among Adolescent Girls

Hanes, Jacob Wobst 07 1900 (has links)
This investigation utilized data from a previous laboratory-based study to examine the interactive contributions of trait involuntary stress responses (ISRs, e.g., rumination) and perceived familial social support (SS) on the hypothalamic-pituitary-adrenal axis (HPA; as indexed via salivary cortisol) response to acute stress in a sample of 128 adolescent girls ages 12 to 16. Participants completed a modified Trier Social Stress Test (TSST), and physiologic stress response was indexed via six salivary cortisol samples. Dimensions of ISRs and familial social support were entered into regression models to predict total cortisol circulation defined by area under the curve with respect to ground (AUCG; Pruessner et al., 2003) following the TSST. Neither ISRs or SS were associated with cortisol AUCG, nor was there an interactive effect of SS on relationships between ISRs and AUCG. Implications of present results and methodological recommendations for future investigations are discussed. This may be the first investigation to consider the interactive effects of ISRs and social support on adolescent girls' HPA responses. Greater understanding of these factors in this understudied demographic will improve translational science as well as inform risk assessment and intervention development.
13

Holistický přístup k pozůstalým při náhlém úmrtí z pohledu všeobecné sestry, členky výjezdového týmu záchranné služby / A holistic approach to the bereaved in case of a sudden death from a nurse´s point of view a member of the medical emergency services

GUTOVÁ, Alena January 2013 (has links)
The dissertation deals with holistic approach of nursing staff of the Rescue Service by providing pszchosicial support and crisis communication to the survivors or direct sudden death participants from nurse´s }member of the Rescue Service team]perspective. The goal of the dissertation has been 1. To detect problems which nursing staff members of the Rescue Service are prepared for communication with the survivors.
14

Welfare Evaluation of Stunning Practices for Farmed Fish in the European Union

Barkerud, Rickard January 2021 (has links)
An optimal method for stunning animals before slaughter should result in instantaneous and irreversible insensibility. Today, there are various stunning and slaughter practices used around the world for farmed fish. With aquaculture being a growing food sector, the welfare of the animals used has become increasingly important in the consciousness of consumers, researchers and regulatory bodies. With growing research into the subject matter, an overview to summarize and examine how these practices impact on the welfare of the fish, and how well they conform to animal welfare legislation, is warranted to minimize the suffering of farmed fish. Stunning practices used in aquaculture include methods such as electrical and percussive stunning, carbon dioxide and asphyxiation. Each with its own level of effectiveness in terms of how fast the method results in loss of consciousness, whether or not the effect is reversible and how the welfare of the fish is affected as determined by behavioural and physiological stress responses. It was concluded that there is no unambiguous answer as to which stunning method is optimal in regard to animal welfare in modern day aquaculture. The optimal method for a given facility is influenced by factors like practicalities relating to each individual method as well as legislation on EU and national level. Suggestions were made for future research.
15

Ancestral Functions of DELLA Proteins

Hernández García, Jorge 16 July 2021 (has links)
[ES] Las plantas necesitan acomodar su crecimiento a las condiciones ambientales. Con el objetivo de ajustar su desarrollo a las señales externas, usan una serie de mecanismos moleculares. Uno de estos son las rutas de señalización hormonal, que participan en integrar la información externa con programas de desarrollo propios. Una de las hormonas más relevantes en la biología vegetal son las giberelinas (GAs). La señalización por GAs se inicia con la percepción de la hormona a través del receptor GID1, y continúa por la degradación de las reguladoras transcripcionales DELLA. Sin embargo, solo las plantas vasculares tienen un sistema de percepción de GAs completo. Entender la relevancia de la señalización por GAs requiere estudiar cómo se ensambló la ruta y qué funciones atribuidas a las GAs estaban ya codificadas en las proteínas DELLA ancestrales. Aquí mostramos mediante análisis filogenéticos y bioquímicos que las proteínas DELLA emergieron inequívocamente en un ancestro común de las plantas terrestres, y que el reclutamiento de las DELLAs al módulo de percepción de GAs depende de la presencia de un dominio de transactivación conservado que fue co-optado por el receptor GID1 ancestral para actuar como un degrón dependiente de GAs. Este dominio de transactivación parece regular la co-activación transcripcional de genes concretos por las DELLAs en todas las plantas terrestres mediante el reclutamiento de complejos Mediator a través de su subunidad MED15. Por último, nos hemos centrado en entender las funciones de las proteínas DELLA en briófitas, un clado sin señalización por GAs. Hemos descubierto el rol de la DELLA de Marchantia polymorpha como coordinadora entre las respuestas de crecimiento y estrés, sugiriendo que dicha función estaba ya codificada en proteínas DELLA del ancestro común de plantas terrestres y se ha mantenido durante más de 450 millones de años. / [CA] Les plantes necessiten acomodar el seu creixement a les condicions ambientals. Amb l'objectiu d'ajustar el seu desenvolupament als senyals externs, usen una sèrie de mecanismes moleculars. Un d'aquests són les rutes de senyalització hormonal, que participen en integrar la informació externa amb programes de desenvolupament propis. Una de les hormones més rellevants en la biologia vegetal són les giberel·lines (GAs). La senyalització per GAs s'inicia amb la percepció de l'hormona a través del receptor GID1, i continua per la degradació de les reguladores transcripcionals DELLA. No obstant això, només les plantes vasculars tenen un sistema complet de percepció de GAs. Entendre la rellevància de la senyalització per GAs requereix estudiar com es va assemblar la ruta i quines funcions atribuïdes a les GAs estaven ja codificades en les proteïnes DELLA ancestrals. Ací mostrem mitjançant anàlisis filogenètiques i bioquímiques que les proteïnes DELLA van emergir inequívocament en un ancestre comú de les plantes terrestres, i que el reclutament de les DELLAs al mòdul de percepció de GAs depén de la presència d'un domini de transactivació conservat que va ser co-optat pel receptor GID1 ancestral per a actuar com un degró dependent de GAs. Aquest domini de transactivació sembla regular la co-activació transcripcional de gens concrets per les DELLAs en totes les plantes terrestres mitjançant el reclutament de complexos Mediator a través de la seua subunitat MED15. Finalment, ens hem centrat en entendre les funcions de les proteïnes DELLA en briòfites, un clade sense senyalització per GAs. Hem descobert el rol de la DELLA de Marchantia polymorpha com a coordinadora entre les respostes de creixement i estrés, suggerint que aquesta funció estava ja codificada en proteïnes DELLA de l'ancestre comú de plantes terrestres i s'ha mantingut durant més de 450 milions d'anys. / [EN] Plants need to accommodate their growth habits to environmental conditions. For this aim, several mechanisms are used to adjust developmental responses to exogenous signals. Among them, hormonal signalling pathways participate by integrating external information with endogenous programs. One of the most relevant hormones in plant biology are gibberellins (GAs). GA signalling involves perception of the hormone by the GA receptor GID1 and subsequent degradation of the DELLA transcriptional regulators. However, only vascular plants possess a full GA perception system. Understanding the relevance of GA signalling requires elucidating how this pathway was assembled and which of the functions attributed to GAs were encoded in the ancestral DELLA proteins. Here we show by phylogenetic and biochemical analyses that DELLA proteins emerged unequivocally in a land plant common ancestor and that their recruitment into the GA-perception module relies in the presence of a conserved transactivation domain co-opted by an ancestral GID1 receptor to act as a GA-dependent degron. Moreover, this transactivation domain seems to regulate DELLA-dependent transcriptional co-activation of selected target genes by recruitment of Mediator complexes through the MED15 subunit in all land plants. Finally, we have focused on understanding the functions of DELLA proteins in bryophytes, a clade with no GA signalling. We have uncovered the role of Marchantia polymorpha DELLA protein as a coordinator between growth and stress responses, suggesting that this function was already present in the DELLA protein of a land plant common ancestor and has been maintained for over 450 millions of years. / La realización de esta tesis doctoral ha sido posible gracias a una ayuda para contratos predoctorales FPU (FPU15/01756), dos Ayudas para Estancias Breves FPU (EST17/00237, IPS2, París; EST18/00400, WUR, Wageningen), una ayuda EMBO Short-Term (ASTF 8239, WUR, Wageningen), y la financiación MSCA H2020 RISE para desplazamientos en el contexto del proyecto SIGNAT (RISE Action 644435, PUC, Santiago). Así mismo, el grueso del trabajo experimental incluido ha sido financiado por el proyecto HUBFUN del MINECO (BFU2016-80621-P) / Hernández García, J. (2021). Ancestral Functions of DELLA Proteins [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/169370 / TESIS
16

La santé psychologique au travail : une modélisation ancrée dans la théorie de la conservation des ressources

Malo, Marie 06 1900 (has links)
Si la santé psychologique au travail retient de plus en plus l’attention de la communauté scientifique et des milieux de pratique, certains aspects du phénomène restent néanmoins à explorer. Notamment, les études se sont peu attardées au fonctionnement de l’individu dans l’organisation, focalisant plutôt sur les expériences subjectives associées au bien-être et à la détresse psychologiques. En outre, l’état des connaissances sur les mécanismes sous-jacents à la santé psychologique au travail demeure embryonnaire. Faute d’écrits sur la question, la compréhension du construit s’avère partielle. Devant ce constat, la présente thèse vise à modéliser la santé psychologique au travail en y intégrant des indicateurs du fonctionnement de l’employé. Dans cette optique, cinq études, regroupées en deux articles, ont été menées auprès de quatre échantillons indépendants (Article 1 : NA = 296, NB = 350, NC = 139; Article 2 : NB = 330, NC = 128; ND = 389). Le premier article a pour objet de développer une conceptualisation et une mesure du fonctionnement de l’individu dans l’organisation. Prenant appui sur les travaux en socialisation organisationnelle et sur la théorie de la conservation des ressources (Hobfoll, 1989, 2001), l’ajustement cognitif au travail est proposé à titre d’indicateur additionnel de la santé psychologique au travail. Des analyses factorielles exploratoires et confirmatoires, de même que des analyses de cohérence interne, d’invariance temporelle et de régression, confirment les qualités psychométriques de l’instrumentation et étayent la validité de l’ajustement cognitif au travail comme indicateur de la santé psychologique au travail. Le second article s’appuie sur la conceptualisation du fonctionnement de l’employé présentée dans le premier article pour tester une modélisation de la santé psychologique au travail. Se fondant sur la théorie de la conservation des ressources (Hobfoll, 1989, 2001), la santé psychologique au travail est modélisée comme un processus incluant quatre indicateurs, soit le bien-être psychologique, la détresse psychologique, l’ajustement cognitif et les réponses comportementales de stress au travail. Deux mécanismes distincts sont mis de l’avant pour expliquer les relations unissant les indicateurs positifs de santé psychologique au travail (c.-à-d., le bien-être psychologique et l’ajustement cognitif) et celles caractérisant les indicateurs négatifs (c.-à-d., la détresse psychologique et les réponses comportementales de stress). Des analyses acheminatoires et d’invariance transculturelle révèlent la présence des deux mécanismes et montrent que, au-delà de l’influence des demandes en emploi, le bien-être psychologique exerce un effet médiateur sur la relation positive entre des ressources personnelles (c.-à-d., optimisme et résilience) et organisationnelle (c.-à-d., climat de travail) et l’ajustement cognitif au travail. Les résultats mettent également en exergue le rôle médiateur de la détresse psychologique sur la relation négative entre les mêmes ressources et les réponses comportementales de stress au travail. Une discussion générale précise la portée des résultats présentés dans le cadre des deux articles. / While psychological health at work is gaining attention from academics and practitioners, certain aspects of the phenomenon need deeper exploration. Notably, scant research has examined individual functioning in the workplace; the majority of studies focused on subjective experiences related to psychological well-being and distress instead. Moreover, little is known about the mechanisms underlying psychological health at work. These shortcomings result in a partial understanding of the construct. In light of these observations, the present thesis aims to develop a model of psychological health at work, integrating indicators of employee functioning. To achieve this goal, five studies divided into two articles were conducted using four independent samples (Article 1: NA = 296, NB = 350, NC = 139; Article 2: NB = 330, NC = 128; ND = 389). The first article proposes a conceptualization and a measurement of individual functioning at work. Building on organizational socialization literature and on conservation of resources theory (Hobfoll, 1989, 2001), we conceptualize cognitive adjustment as a psychological health indicator. Exploratory and confirmatory factor analyses, as well as reliability, temporal invariance and regression analyses, confirm the psychometric qualities of the instrument and support the validity of cognitive adjustment at work as, indeed, an indicator of psychological health. Drawing from the conceptualization of employee functioning reported in the first article, the second article tests a model of psychological health at work. Based on conservation of resources theory (Hobfoll, 1989, 2001), psychological health at work is conceptualized as a process, which includes four indicators, namely psychological well-being, psychological distress, cognitive adjustment, and behavioural stress responses at work. Two distinct mechanisms are put forward explaining the relations between positive indicators (i.e., psychological well-being and cognitive adjustment), and the relations between negative indicators (i.e., psychological distress and behavioural stress responses). Path and cross-cultural invariance analyses acknowledge both mechanisms, and demonstrate that, beyond the impact of job demands, psychological well-being exercises a mediating effect on the positive relations between personal (i.e., optimism and resilience) and organizational (i.e., work climate) resources, and cognitive adjustment at work. Results also highlight that psychological distress mediates the negative relations between the same resources and behavioural stress responses at work. A general discussion covers in deeper details the implications of the findings emanating from both articles.
17

Réponses écophysiologiques et moléculaires des plantes aux stress xénobiotiques complexes de faible intensité : implications dans les capacités de protection environnementale des bandes enherbées / Ecophysiological and molecular responses of plants to complex xenobiotic stress of low intensity : implications in the environmental protection capacities of vegetative filter strips

Serra, Anne-Antonella 05 March 2015 (has links)
Les pollutions par les xénobiotiques, en particulier les pesticides, et les métaux lourds issus des activités agricoles présentent une grande complexité de composition chimique et de dynamique spatio-temporelle. La présence de bandes enherbées entre les parcelles cultivées et les cours d’eau permet une limitation de la diffusion de ces pollutions résiduelles vers les milieux naturels. Le compartiment végétal de ces bandes enherbées peut jouer de multiples rôles dans ce contexte de protection environnementale. L’étude comparative réalisée in situ et en conditions contrôlées de laboratoire a permis de mettre en évidence le rôle biologique du compartiment végétal avec son implication directe dans les processus in planta d’absorption, de stockage et/ou de dégradation au moins partielle. Un tel rôle phytoremédiateur est dépendant de la capacité des plantes à se maintenir sur ces milieux pollués, qui diffère selon l’espèce considérée et structure ainsi les communautés végétales des bandes enherbées. L’étude intégrative en conditions contrôlées des réponses des plantes aux interactions avec les xénobiotiques à faibles doses, à différentes échelles de complexité du fonctionnement végétal, a permis de montrer les effets de ces stress chimiques chez l’espèce modèle Arabidopsis thaliana et chez l’espèce prairiale Lolium perenne. Les xénobiotiques et les métaux lourds à des doses subtoxiques ont induit d’importants bouleversements métabolomiques et moléculaires chez ces espèces, avec des effets cryptiques de ces polluants et de leurs produits de dégradation. L’analyse en conditions de multi-pollution, qui reflètent de manière réaliste les pollutions péri-agricoles, a montré la complexité et la difficulté de prédiction des interactions entre les effets des contaminants en mélange. Ces mécanismes de réponses diffèrent selon l’espèce et le polluant et laissent supposer des divergences en termes de perception et/ou de transport des polluants, ou de coordination des réponses moléculaires et métaboliques. Arabidopsis a ainsi présenté une coordination de ses réponses orientée vers une augmentation des métabolites de stress, et une diminution des métabolites carbonés (sucres solubles), en parallèle de modifications de l’expression de gènes impliqués dans les défenses antioxydantes, les défenses contre les stress xénobiotiques, ou dans la dynamique des phytohormones. Le stress chimique a entraîné chez Lolium des modifications majeures du métabolisme azoté, ainsi qu’un remaniement des processus de photorespiration. L’analyse transcriptomique de cette espèce a de plus montré que la majorité des gènes identifiés sont impliqués dans des voies de transduction de signal, montrant ainsi la complexité des mécanismes de réponse et les couplages qui existent entre les signaux métaboliques, en particulier liés aux sucres, les voies de signalisation associées aux phytohormones, les signaux de stress et la photosynthèse. / Environmental pollutions by xenobiotics, especially by pesticides and heavy metals derived from agricultural activities, show an important complexity of chemical composition and of spatiotemporal dynamic. Vegetative filter strips between cultivated fields and streams limit the diffusion of these residual pollutions to natural environments. However, the exact biological role of plant in these buffer strips is poorly understood in this context of environmental and ecological protection. A comparative study carried out in situ and in controlled conditions highlighted the role of plant compartment in the processes of absorption, storage and/or partial degradation of pollutants in planta. Such capability of phytoremediation depends on the maintenance of a vegetal cover in area subjected to recurring flow of pesticides, it varies according to species and leads to the structuration of vegetative filter strip communities. An integrative study in controlled conditions of plant responses to low doses of pollutants allowed to analyze at different levels of complexity the impacts of chemical stresses on the model species Arabidopsis thaliana and the grassland species Lolium perenne. Low and sublethal doses of xenobiotics, associated degradation products and heavy metals induced cryptic perturbations at metabolic and molecular levels. Multi-pollution analyses, which reflect realistic conditions of environmental exposure, highlighted complex interactive effects between pollutants in mixture and the difficulty to predict them. The mechanisms of response to these chemical stresses differ according to the species and the pollutant, and suggest differences in term of perception and/or transport of pollutants, or of coordination of molecular and metabolic responses. Arabidopsis presented a coordination of its responses toward an increase of stress metabolites, a decrease of carbon metabolites (soluble carbohydrates), in parallel with modifications of gene expressions implicated on antioxidant defences, defence against xenobiotic stresses, or phytohormone dynamic. Chemical stress leads to major modifications of nitrogen metabolism in Lolium, and perturbations of processes of photorespiration. De novo transcriptomic analysis of Lolium therefore showed that a majority of identified genes are related to signal transduction pathways, highlighting the complexity of response mechanisms and the links between metabolic signals, especially linked to carbohydrate, hormonal signaling pathways, stress signals and photosynthesis. Subtoxic chemical stress induced cryptic re-engineering of plant processes that may explain the development of tolerance for some species and their persistence in area affected by residual pollution.

Page generated in 0.0911 seconds