The most universal abiotic influence is temperature, and thus, thermotolerance, adaptations and response to thermal variation, is a fundamental factor shaping evolution. Prokaryotic life may have an upper thermal limit near \(150^{\circ}C\); however, eukaryotic survival is limited to \(50^{\circ}C\) – the thermal maximum for sustained biosynthesis and homeostasis. My research focuses on understanding the physiological and biochemical factors that limit eukaryotic thermotolerance, by studying an organism near the upper limit of all eukaryotes: Paralvinella sulfincola. P. sulfincola, a hydrothermal vent polychaete, has the broadest known thermal range of any metazoan: \((5-48^{\circ}C)\). This species, along with the mesotolerant congener with Paralvinella palmiformis, is found at vents along the Juan de Fuca Ridge, Washington, USA. Making an ideal study system, both species are found in similar habitats, genetically comparable, and amenable to recovery and shipboard experimentation. Here, I present data from a series of high pressure in vivo experiments that investigate stress response to variations in temperature, pH, sulfide concentration, and duration. Field work was coupled with a suite of biomolecular techniques including pyrosequencing, comparative proteomics, enzyme assays, and quantitative PCR. From this research, the first to quantify global protein and antioxidant responses to temperature in an extremely thermotolerant eukaryote, three primary conclusions can be reached. 1) Pronounced thermal tolerance in P. sulfincola is likely enabled by its constitutive expression of heat shock proteins and limited by its ability to quickly and appropriately respond to the commensurate increase in oxidative stress. 2) Thermal tolerance limits are likely negatively affected by synergistic multistress effects. 3) Antioxidant gene expression response differs significantly between chronically and acutely stressed treatments, supporting the theory that oxidative stress is limiting in this system.

Electrical and electronic device insulation systems experience multiple stresses while in service. Insulation design engineers usually make attempts to study the behavior of insulation under multiple stresses to keep the size and weight of the electrical insulation at a minimum. In this thesis, magnet wire insulation properties under multiple stresses are studied. Magnet wires are used for insulation in transformers, flyback transformers, solenoids, sensors, motors, adjustable speed drives etc. The magnet wire insulation under study in this work is micrometers thick, yet they are expected to provide high breakdown strength, good windability, and resistance to moisture. Accelerated life tests are performed on two different AWG 43 magnet wires. Combined Weibull Electrical-Thermal life models and Electrical-Thermal-Frequency life models were successfully verified in this work. The statistical information like lifetime characteristics, probability of failures, and lifetime percentiles determined for the two different magnet wire insulation is helpful for a better understanding of their insulation properties.

This work deals with the influence of multistress ageing (electrical and thermal stress) to relaxation effects depending on defined conditions had being labored.

The diploma thesis with experimental verification influence moisture of the dielectric properties of non-aged and thermally, electric and multistress aged slot insulation Isonom NMN. Above all both components of the complex permittivity are examined in dependence on frequency during the thermal, electric and multistress ageing. Practical part is specialized on design, realization and examination of workplace multistress ageing.

Diploma thesis treat of effect of thermal, electrical and combined (thermal electrical) stress on electrical characteristics of insulation material ISONOM NMN which is used as a slot insulation in electric motors. To monitor the stress is used the method of dielectric relaxation spectroscopy. Under examinations are the resultant dielectric spectra which constitute the frequency dependencies of components of complex permitivity. Compared are the effects of particular stresses on dielectric spectra of surveyed insulative material.

Les plantes sont des organismes immobiles qui doivent répondre et s’adapter à des contraintes abiotiques et biotiques. Parmi les stress biotiques, les maladies virales, établies ou émergentes, peuvent être responsables de pertes de rendement majeures aux conséquences économiques importantes. Face aux phytovirus la lutte génétique constitue le moyen de lutte le plus efficace, le plus respectueux de l’environnement et du consommateur. Comprendre l’interaction entre les plantes et les virus reste indispensable pour rechercher de nouvelles sources de résistances. Ce travail de thèse s’intéresse à l’étude du pathosystème naturel Arabidopis thaliana/Turnip mosaic virus (TuMV). Les essais ont été menés majoritairement en conditions extérieures permettant une analyse de l’interaction dans un environnement multistress. La réponse d’A. thaliana a été explorée par l’étude de traits liés à la maladie et par la variation en métabolites primaires et secondaires. Ce travail a permis i) de caractériser de façon fine la réponse d’A. thaliana au TuMV en conditionsmultistress en exploitant la diversité naturelle d’une population mondiale et française ii) de déterminer l’architecture génétique de cette interaction par des approches de génétique d’association et de QTL mapping. Plusieurs nouveaux loci potentiellement impliqués dans la réponse ont été identifiés iii) de montrer l’intérêt du phénotypage métabolique pour discriminer les accessions en fonction de leur sensibilité au TuMV. La multidisciplinarité des approches constitue la richesse de ce travail de thèse qui contribue à une meilleure caractérisation et compréhension de la réponse des plantes lors d’une infection virale. / Plants are immobile organisms which have to adapt to abiotic and biotic constraints. Among bioticstress, established or emerging viral diseases, may be responsible for major yield losses withsignificant consequences. Genetic control is the most effective, environmentally and consumerfriendlyway to control viral infections. Understanding plant/virus interactions remains essential tosearch for new sources of resistance. This work, focuses on the study of the natural pathosystemArabidopsis thaliana/Turnip mosaic virus (TuMV). Most of the trials were conducted in commongarden conditions allowing the analysis of the interaction in a multistress environment. A. thaliana’sresponse was explored through the study of disease-related traits and the variations in primary andsecondary metabolites. This work allows i) the fine characterization of A. thaliana’s response toTuMV in multistress conditions through the exploration of the natural diversity of a world and Frenchpopulation ii) to determine the genetic architecture of this interaction by genome wide associationsand QTL mapping. Several new loci potentially involved in the response have been identified iii) tohighlight the interest of metabolic phenotyping to discriminate accessions according to theirsusceptibility to TuMV. The multidisciplinary approaches contribute to a better characterization andunderstanding of plant-virus interaction.

This diploma thesis deals with not-aged and thermally, electric and multistress aged slotted isolations dielectric properities experimental probing. Dutiny experiment is watched influence moisture on dielectric properties insulating materiále ISONOMŽNMN. Especially both two permitivity complex components are surveyed, in dependence on the frequency and the temperature changes during thermal, electric and multistress ageing. These characteristics are viewed in light of application the isolation in practice.