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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.
41

Krize středního věku / Midlife crisis

Pilná, Jana January 2015 (has links)
: Midlife Crisis is a very popular concept describing middle adulthood. Faced with imminent death, people stop on the way to achieve their goals, to review their achievements and to assess what you already have and what you still want to achieve to fulfill their dreams. The theoretical part deals mainly with the definition of middle adulthood, midlife crisis, life satisfaction and personal well-being and also presents an overview of basic theories and research on these topics. Empirical part is focused on finding how this concept is understood and whether their own lives and the lives of their loved ones this stage recognize as life stage specific symptoms within the definition of midlife crisis and how this developmental stage experience. The work also deals with the psychological differences in experiencing developmental stages middle-aged men and women and ways of coping. Key words: middle age, crisis, adulthood, life span development, individuation, life review
42

Studium jevů limitujících životnost sekundárních článků Ni-Zn / A Study of Phenomena that Limit the Life-Span of Ni-Zn Secondary Cells

Chladil, Ladislav January 2014 (has links)
This dissertation is focused on the study of selected additives and their effect on positive and negative electrodes of Ni-Zn secondary cells. The first group of additives consists of the inorganic compounds that reduce zinc oxide solubility and thus prevents shape changes of the zinc electrode. The second group contains organic additives that have the beneficial effect of dendrite growth prevention. All additives were examined in relationship to their compatibility with the positive electrode and to their effect on the zinc electrode dendrites inhibition, hydrogen evolution and corrosion inhibition. Moreover, the study of decomposition kinetics of supersaturated zincate solution with the first group of additives was performed. Finally, a short study of pulse regime charging mode with regard to dendrites inhibition was performed and evaluated.
43

Analys av byxors kvalitet genom simulerad användning : En undersökning av vilka kvalitetsparametrar som förkortar en vävd byxas användningstid / Quality analysis of trousers through simulated use

Gustafsson, Jonnah, Nilsson, Marcus January 2022 (has links)
En textilprodukts produktionsprocess beräknas stå för 80% av dess totala klimatutsläpp. Produktionen förorenar både vatten och land. Ännu är inte återvinning svaret på den negativa klimat- och miljöpåverkan som den textila värdekedjan medför. All textilproduktion och återvinning kräver resurser i form av vatten, kemikalier och energi. Enligt studier konsumerar den genomsnittliga svensken 14 kg textilier varje år men den tid som textilierna används blir kortare och kortare på grund av bristfällig kvalitet. Inom cirkulär textil är en viktig del återanvändning, för att det skall kunna ske i högre utsträckning är det av vikt att de textilier som produceras är av god kvalitet. Idag kvalitetstestas nyproducerade, oanvända och konditionerade plagg direkt efter produktion enligt gällande standarder genom mekaniska påfrestningar, ofta testas slitaget tills det inte längre kan anses vara acceptabelt ur ett kundperspektiv. Dessa tester mäter dock inte den verkliga användningen. Vilket innebär att det inte finns något verkligt underlag för att avgöra om det material som använts har en tillräckligt god kvalitet för att hålla för verklig användning och slitage i ett längre perspektiv eller bara uppfyller kravspecifikationen som upprättats. Arbetet i denna rapport har haft som syfte att identifiera vilka kvalitetsbrister som uppstår vid användning av plagg och genom simulerad användning med hjälp av standardiserade testmetoder försökt utvärdera plaggens fysiska livslängd. För att om möjligt kunna användas av företag i samma syfte. Som fallstudie har ett företag studerats och sex olika byxor har testats. Kvalitativa och kvantitativa studier resulterade i ett antal tester till att simulera användning för att försöka utvärdera plaggens fysiska livslängd. De valda testerna för att simulera slitage var upprepad tvätt, nötningshärdighet och rivstyrka, färgförändring, och dimensionsstabilitet vilka har representerat de visuella kvalitetsbrister som kan uppstå. Resultaten från testerna visar att de vanligaste kvalitetsbrister som konsumenter upplever är att det uppstår hål i materialet, att plagget tappar form och att det sker färgförändringar. En av sex byxor uppfyllde kraven i de tester som utförs för validering av testutrustningen. Efter att samtliga byxor testats enligt de utvalda metoderna var det ingen byxa som uppfyllde alla de ställda kraven. Slutsatsen av arbetet är att simulerad användning inte är omöjligt som metod men det går inte fullt ut att återskapa det mekaniska dagliga slitage som ett plagg genomgår hos konsumenten. För att bli en fullgod metod behöver ett mer omfattande arbete göras. Det går inte att med de resultat som återfinns i arbetet att ge konkreta förslag på förbättringar för en ökad livslängd. Det krävs utförliga kravspecifikationer för plaggen som gäller för en hel livslängd. Vilka inte är generella utan uppförda för de olika produktkategorierna i större detalj för att ha kontroll över hela produktionskedjan. / The production process for textiles is estimated to be responsible for 80 % of the total climate emissions made by the industry. The production pollutes both water and land. Recycling, though on the rise, does not offer the necessary solution at the time to deal with the negative climate- and environmental impact of the textile industry. All textile production including recycling requires resources in the form of water, chemicals and energy. The average Swede consumes 14 kg of textiles annually, but the user time is decreasing because of defective quality according to studies. In circular textiles the term re-use is of importance, and to possibly implement it to a greater extent it is of importance that the textiles produced are of good quality making it more probable that the end use will be prolonged. Today, a garment is tested unused and conditioned directly after production, according to standardized test methods through the means of mechanical wear, which is measured to the point where the wear is considered nonacceptable from a consumer perspective. However, these tests do not measure the real wear and tear. Meaning there is no proper basis to decide whether the material used, reaches the level of quality needed for real use in a larger perspective or if it just fulfills the set requirements. The purpose of this project has been to identify what quality deficiencies consumers experience during the use-phase of garments. Through simulated use according to standardized test methods, evaluate the physical lifespan of the garments. With the prospect that fast-fashion companies can implement it to ensure the quality of their materials. As a case study, a company has been studied and six different trousers have been tested. Qualitative and quantitative studies resulted in several tests to simulate use to try to evaluate the physical life of the garments. The tests chosen to simulate wear were repeated washing, abrasion resistance, tear strength, color change, and dimensional stability which represented the visual quality defects that may occur. The test results showed that the most common quality deficiencies that consumers experience are breakage in the material, shape and color changes. One out of six trousers met the requirements of the tests performed for the validation of the test equipment. After all trousers were tested according to the selected methods, no trousers met the set requirements. In conclusion simulated use is not undoable as a method but it cannot fully recreate the mechanical daily wear and tear that a garment undergoes during the user-phase. For it to become an effective method, more extensive work needs to be carried out. It is not possible with the results drawn from this study to give concrete suggestions for improvements for increased longevity. Detailed garment, yarn and requirements specifications are essential. They need to be in greater detail for the various product categories and not be general for all.
44

[In]stability in the use of a stable variable

Mechler, Johanna, Buchstaller, Isabelle 18 April 2024 (has links)
The relationship between community-wide change and patterns of variation and change within the individual is one of the cornerstones of variationist theorising. But while sociolinguistic theory makes clear and testable predictions regarding the use of stable vernacular features across the life-span of the individual, we lack real-time evidence on the age-graded nature of stable variability. Indeed, whereas apparent time research highlights the diachronic stability of (ing), only two research projects have explored its use within the individual speaker. Both report on pre-adult speakers. Our research expands the window of analysis by adding a later age-bracket to the investigation of age-graded variability. We consider the variable realisation of (ing) in a group of individuals between early adulthood and retirement.
45

Le vieillissement chronologique de Schizosaccharomyces pombe : Implication des voies de détection du glucose

Roux, Antoine E. 04 1900 (has links)
La première augmentation de la longévité en laboratoire fût observée à la suite d’une intervention nutritionnelle consistant en une réduction de l’apport alimentaire chez le rat. Plus tard, ce phénomène a été reproduit dans de très nombreuses espèces et référé en tant que restriction calorique. Le développement des techniques de biologie moléculaire moderne a permis de montrer dans des organismes modèles simples que cette flexibilité du processus de vieillissement était régulée par des facteurs génétiques. De fait, plusieurs mécanismes cellulaires ont alors pu être identifiés comme responsables de ce contrôle du vieillissement. Ces voies de régulation ont révélées être conservées entre les espèces, depuis les levures jusqu’aux organismes multicellulaires tels que le nématode, la mouche ou la souris, suggérant l’existence d’un programme universel de vieillissement dans le vivant. La levure s’est avéré à plusieurs reprises être un modèle puissant et fiable pour la découverte de gènes impliqués dans ce phénomène. Mon étude a consisté au développement d’un nouveau modèle unicellulaire d’étude du vieillissement à travers l’espèce Schizosaccharomyces pombe appelée aussi levure à fission. La première étape de mon travail a montré que les voies de détection des nutriments gouvernées par la sérine/thréonine protéine kinase A (Pka1) et la sérine/thréonine kinase Sck2 contrôlent le vieillissement chronologique de ces cellules comme il était connu dans la levure Saccharomyces cerevisiae. Ceci permit de valider l’utilisation de la levure à fission pour l’étude du vieillissement. Ensuite, nous avons analysé plus en détail l’effet pro-vieillissement du glucose en étudiant le rôle de sa détection par le récepteur membranaire Git3 couplé à la protéine G (Gpa2) en amont de la kinase Pka1. La perte du signal du glucose par la délétion de Git3 imite partiellement l’effet d’augmentation de longévité obtenu par baisse de la concentration en glucose dans le milieu. De plus, l’effet néfaste du signal du glucose est maintenu en absence de tout métabolisme du glucose suite à la mutation des hexokinases, premières enzymes de la glycolyse. L’ensemble de ces résultats suggèrent que la signalisation du glucose est prédominante sur son métabolisme pour son effet pro-vieillissement. D’autre part, à la fois la suppression de cette signalisation et la baisse de niveau de glucose disponible allongent la durée de vie en corrélation avec une augmentation de la résistance au stress, une hausse d’activité mitochondriale et une baisse de production de radicaux libres. Finalement, le criblage d’une banque de surexpression d’ADNc a permis d’identifier plusieurs gènes candidats responsables de ces effets en aval de la voie de signalisation Git3/PKA. La recherche sur les mécanismes moléculaires du vieillissement propose une nouvelle approche, un nouvel angle de vue, pour la compréhension des fonctions cellulaires et promet d’apporter de précieuses clefs pour mieux comprendre certaines maladies. En effet, le vieillissement est la première cause d’apparition de nombreuses affections comme les cancers, les maladies cardiovasculaires et métaboliques ou les maladies neurodégénératives tels que les syndromes d’Alzheimer et de Parkinson. / The first increase in life span due to man’s intervention was obtained with rats subjected to a diet reduced in calorie intake. Later, this phenomenon was repeated with many other species and referred as diet restriction or calorie restriction. The development of modern Molecular Biology approaches and the use of simple model organisms demonstrated that the rate of aging was regulated by genetic traits. Indeed, several cellular mechanisms were identified as responsible for the control of aging. These regulatory pathways appear to be conserved throughout species, from yeast to multicellular organisms like nematode, fly and mice, thus suggesting the existence of a universal program of aging. Yeast proved several times to be a powerful and reliable model for discovering genes involved in the regulation of aging. My study consisted in developing Schizosaccharomyces pombe (also called fission yeast) as a new unicellular model to study aging. The first step of my work was to show that pathways of nutrient detection through kinases involving Pka1 and Sck2 control chronological aging in S. pombe, as it was previously demonstrated in Saccharomyces cerevisiae. This first work validated the use of fission yeast for the study of aging. Subsequently, we analysed in more detail the pro-aging effect of glucose focusing on the role of its signalling through the G-protein Gpa2-coupled membrane receptor Git3, which acts upstream of Pka1. The loss of the glucose signal due to deletion of Git3 mimics partially the effect of increasing longevity by reducing glucose in the medium. Moreover, detrimental effects of glucose signal are maintained in absence of sugar metabolism following loss of hexokinases, the first enzymes of glycolysis. Together, these results suggest that the pro-aging effects of glucose signalling are predominant over those due to metabolism of this sugar. Moreover, both obliteration of this signalling pathway and decrease of glucose availability extend life span, and correlate with an increase in stress resistance, in mitochondrial activity and a lower production of free radicals. Finally, screening a cDNA-overexpression library allowed us to identify several genes candidates responsible for the effects on longevity downstream of Git3/Pka1. Research in the molecular mechanisms of aging propose holds the promise to bring precious clues as to this mysterious processes affecting all living creatures, and paves the way to unravel the underlying causes of many human diseases. Indeed, aging is the first cause of numerous late-onset pathologies including cancers, cardiovascular diseases or neurodegenerative diseases like Alzheimer and Parkinson syndromes.
46

Continuing education of older workers

Thieme, Paula 26 November 2015 (has links)
In den letzten Jahrzehnten führten abnehmende Geburtenraten und die zunehmende Lebenserwartung zur Alterung der deutschen Bevölkerung. Zur Sicherung des Rentensystems wurde das Renteneintrittsalter auf 67 Jahre angehoben. Um die Arbeitsfähigkeit zu erhalten und den technologischen wie organisationalen Wandel zu bewältigen, fordert die Europäische Union zum lebenlangen Lernen auf. Diese Dissertation bietet einen Literaturüberblick und drei empirische Aufsätze, die die Weiterbildungsmotivation älterer Arbeitnehmer auf ihre demographische Relevanz untersuchen und altersspezifische Einflüsse von arbeitsbezogenen Faktoren sowie Altersheterogenität belegen. Der Literaturüberblick erläutert die demografische Relevanz älterer Arbeitnehmer, ihren Altersübergang, ihre Arbeitsmotivation und Weiterentwicklung. Anhand von Querschnittsdaten wird der positive Zusammenhang von Weiterbildungsmotivation mit Arbeitsfähigkeit und dem Weiterbeschäftigungswunsch gezeigt. Die Weiterbildungsmotivation Älterer ist über alle Befragtengruppen hoch, was darauf hin deutet, dass Partizipationsungleichheiten weniger von unterschiedlichen Motivationslagen, sondern von anderen Barrieren abhängen. Eine weitere Analyse identifiziert altersspezifische Unterschiede in Hinblick auf den Einfluss von Arbeitsplatzfaktoren auf die Weiterbildungsmotivation. Es zeigen sich schwache aber signifikante Einflüsse einiger Faktoren. Anhand von Längsschnittdaten lässt sich zunehmende Altersheterogenität in Bezug auf die Zufriedenheit mit dem Leben, Arbeit, Familienleben und Gesundheit feststellen. In der Zusammenfassung ist die Weiterbildungsmotivation älterer Arbeitnehmer hoch, sie wird durch den Arbeitskontext beeinflusst und hängt positiv mit der Arbeitsfähigkeit und dem Weiterbeschäftigungswunsch im Rentenalter zusammen. Übliche Mittelwertanalysen älterer Arbeitnehmer haben nur begrenzte Aussagekraft. / Decreasing birth rates and increasing life expectancy have led to the ageing of the German population during the past decades. To sustain the German retirement system, retirement age is increased to 67 years. The European Union calls for individuals’ lifelong learning to maintain work ability and cope with challenges of technological and organisational change. This dissertation consists of a literature overview and three empirical essays investigating older workers’ motivation to participate in continuing education (MPCE) and its demographic relevance, highlighting age-specific work context influences and providing evidence for older workers’ heterogeneity. The literature overview delineates older workers’ demographic relevance as well as their transition to retirement, work motivation, development opportunities, and education. Second, the analysis of cross-sectional data establishes the relevance of older workers’ MPCE for the policy of prolonging working life by showing the positive relationship with work ability and the desire to work past retirement age. Older workers’ MPCE is high across all respondent groups, implying that inequalities in participation are less a result of varying motivation among subgroups, but of other barriers. Following this, work context-related motivational differences between older and younger workers are identified and analysed. Results show weak but significant influences of some work context factors. The analysis of longitudinal data shows ageing workers’ increasing heterogeneity of life satisfaction and satisfaction with work, family life, and health, corroborating life-span theories. In sum, MPCE is high among older workers. It is influenced by work context, and positively related to work ability and the desire to work past retirement age. Common mean-level analyses of older workers yield only limited informative value.
47

Efeito do nitrogênio sobre o desenvolvimento foliar e sua consequência na estrutura da copa em Senna alata (L.) Roxb. (Leguminosae) / Effect of nitrogen of leaf development and its consequences in the canopy vertical structure in Senna alata (L.) Roxb. (Leguminosae)

Marabesi, Mauro Alexandre 13 October 2011 (has links)
O tempo de vida e o desenvolvimento foliar sempre foram questões que intrigaram a humanidade, para além da questão científica, há um interesse até mesmo estético, uma vez que as folhas senescentes do hemisfério Norte e algumas do hemisfério Sul mudam sua coloração de verde para vermelho ou para um amarelo vistoso. Do ponto de vista científico o tempo de vida foliar está associado à produtividade das plantas, bem como às características estruturais das folhas. No entanto, a maioria dos trabalhos enfoca apenas a folha individualmente e não aborda o ponto que o tempo de vida foliar é, na verdade, um produto das taxas de nascimento e de mortalidade que ocorrem no nível da copa. Este é provavelmente o fator que faz com que haja um grande contraste na literatura sobre o tempo de vida foliar. Do ponto de vista ecológico analisam-se apenas as consequências do tempo de vida foliar, sem levar em consideração os mecanismos fisiológicos responsáveis pela mortalidade. Os trabalhos fisiológicos, por outro lado, enfocam em causas da mortalidade - o aumento na quantidade de hexoses e/ou mudanças nos reguladores de crescimento - sem levar em consideração as conseqüências do tempo de vida foliar. Este trabalho visa integrar estas duas visões. Como o nitrogênio é um dos minerais que possuem um efeito profundo no tempo de vida foliar, este foi usado como ferramenta para modificar o tempo de vida foliar de plantas de Senna alata, uma planta pioneira da família Leguminosae, que apresenta crescimento rápido. Foram realizados dois experimentos. No primeiro foi definida a melhor fonte de nitrogênio para o desenvolvimento da planta usando concentrações iguais de NO3, NH4 e NH4NO3. E no segundo experimento foi estudado o efeito de diferentes concentrações da melhor fonte. Em ambos os casos, a expansão, a biomassa, a fotossíntese (somente no segundo experimento) e teores e composição de carboidratos não estruturais, foram acompanhados para cada folha da planta. No primeiro experimento observou-se que ocorreu um aumento na taxa de mortalidade sem efeito na taxa de iniciação foliar, este fato levou a uma diminuição na longevidade das folhas, o que diminuiu o número de folhas na copa, mas não alterou a estrutura vertical da copa. A quantidade de hexoses na fase de senescência parece estar envolvida com o aumento na taxa de mortalidade através do mecanismo sensor de açúcares e como atuou diminuindo o tempo de senescência das folhas, levou a uma mudança no desenvolvimento foliar. No segundo experimento não houve diferença na mortalidade, mas um aumento na iniciação foliar, assim, conforme a concentração de nitrogênio aumentou, a longevidade das folhas tendeu a aumentar e o número de folhas na copa aumentou, mudando a estrutura vertical desta. Como obervado no primeiro experimento, a baixa concentração de hexoses durante a fase de maturidade pareceu ser o mecanismo que impediu a senescência foliar e que, portanto, modificou o desenvolvimento foliar por aumentar a sua fase de maturidade / Leaf life and development have always been intriguing aspects of nature. Even beyond the scientific scope, the aesthetics of such natural processes, illustrated in many different cases, such as when senescent northern hemisphere leaves (as well as some leaves found in the southern hemisphere) change colors from Green to re dor bright yellow. From a scientific standpoint, leaf life span is related to the plants′ productivity, as well as the structural characteristics of the leave themselves. Unfortunately, most current academic studies focus specifically on leaves, neglecting the fact that leaf life span is intimately related to birth and mortality rates at the canopy. This is possibly the greatest issue surrounding academic controversies and discussions regarding leaf life span. From na ecologic perspective, only the consequences deriving from leaf life are analyzed, while all mortality-related physiological mechanisms are not considered. Physiological studies, on the other hand, focus on causes of mortality - increased amount of hexoses and/or changes in growth regulators - but fail to consider the consequences of leaf life span. This article attempts to integrate both standpoints. As one of the minerals with greatest effect on leaf life span, nitrogen Will be used as a way to alter leaf life span during the experiments. In the first experiment we Will establish the most adequate nitrogen source, using the same NO3, NH4 and NH4NO3 concentrations. In the second experiment, we Will assess the effect of different concentrations in such nitrogen source. The first experiment indicated na increase in the mortality rate with no impact over the leaf initiation process, which decreased leaf life span and the amount of leaves in the canopy, but did not change the canopy vertical structure. The amount of hexoses in the senescence phase is responsible for the mortality rate increase and, by shortening the leaves′ senescence process, ultimately changed the leaves′ development. The second experiment did not indicate changes in the mortality rate, but prompted the leaf initiation process. Therefore, as the nitrogen concentratio increased, so did the leaves′ life span and the amount of leaves in the canopy, altering its vertical structure. During the maturity phase, the low hexose concentration seemed to be the mecanism responsible for hidering the leaf senescence process and, therefore, modified the leaves′ development by the increasing the maturity phase.
48

Etude des effets des préparations de surface avant projection thermique : application barrière thermique / Effects on adhesion mechanisms of prior-surface treatments before thermal spraying : Thermal barrier coating

Kromer, Robin 05 December 2016 (has links)
L'adhésion des revêtements est l'objectif premier de tout système afin de pouvoir apporter les propriétés de surface voulues par projection thermique. De façon conventionnelle, des traitements de sablage sont régulièrement employés afin de promouvoir des phénomènes d'ancrage mécanique entre les deux matériaux mis en contact.Néanmoins, selon la nature même des matériaux, un certain nombre de limitations peuvent être observées aussi bien d'un point de vue usage que tenue. Une fragilisation des surfaces peut en effet être remarquée dès lors qu'ils'agit du traitement de matériaux ductiles. Pour palier certaines de ces contraintes, des traitements palliatifs sont alors recherchés parmi lesquels les traitements laser apparaissent particulièrement bénéfiques dont la texturation laser. Les revêtements barrière thermique sont l'application visée de cette étude avec comme objectif une optimisation de leur durabilité à chaud (oxydation, fluage). Une sous-couche d'accroche est habituellement déposée mais les modes d'endommagement recensés semblent se concentrer autour de cette dernière. L'objectif de c etravail a donc visé à remplacer la sous-couche par une topographie de surface spécifique du substrat générée partexturation laser et permettant un ancrage mécanique suffisant aux chargement mécaniques et thermiques subis par les aubes de turbines hautes températures.Lors de l'interaction laser-matière, une élévation en température de l'extrême surface jusqu'à la température defusion et de vaporisation du matériau peut être observée et permettre la formation de motifs. Les dimensions de tels motifs sont donc liées à l¿énergie par impulsion et au nombre d¿impulsions. Pour valider de tels effets, les mécanismes de perçage ont donc été étudiés grâce à une modélisation thermo hydraulique et une validation postmortem des échantillons. Les dimensions des motifs alors contrôlées, le remplissage des surfaces texturées par des particules fondues projetées par le procédé APS a été étudié afin de minimiser le nombre de défauts proche de l'interface. Deux modes de rupture ont pu être identifiés en fonction de la morphologie de surface pour descontraintes de traction et de cisaillement. Les fissures se propagent à l'interface jusqu'à avoir des changements dedirection. L'énergie de propagation de la fissure augmente donc jusqu'à atteindre une valeur limite correspondant àla ténacité du revêtement. Dans ce cas, la tenue n'est pas fonction de la surface totale en contact mais de larépartition spatiale et l'ouverture des motifs, la seule limite de la tenue du revêtement restant la cohésion du dépôt.D'un point de vue applicatif, le but de cette étude a été de caractériser les modes d'endommagements de systèmes barrière thermique sans sous-couche pour des conditions rencontrées en service. Les mécanismes d'endommagement dus à l'oxydation et à l'allongement viscoplastique à 1100C ont donc été isolés par des essais àdes flux thermiques isothermes et cyclés, de fluage et de fatigue thermomécanique. Le traitement laser modifiant localement la microstructure des surfaces, une modification des couches d'oxydes a tout d'abord pu être identifiée.En effet, contrairement aux traitements conventionnels où la croissance d'oxyde n'est pas constante (point limitant de la durée de vie du système), l'apparition de spinelles et d'une couche dense d'alumine protectrice en surface des matériaux texturés a pu être observée. L'ancrage mécanique ainsi créé a démontré alors une durée de vie nettement améliorée face à des conditions extrêmes. / Coating adhesion is requiered to rpomote specific surface properties by thermal spraying. Conventional prior-surface treatments have been developed to create anchoring zones but the adhesion strenght and their applications are limited. Laser surface texturing increases and adapts the adhesion surface. Therefore, two interface failure modes have been related to texture morphologies for tensile and shear stresses. The energy released rate at the interface increases up to coating toughness when the crack path is sharp. Mixed-mode failures have been observed with adhesive and cohesive cracks around and above pattern respectively. So, the adhesion stengyh is function of the contact aera precisely linked to pattern distribution and morphology. Thermal barrier coating system without bond coat life-span has been evaluated for thermomechanical stresses (YSZ coating on single crystal based Nickel). The bond coat has been remplaced by an adapted substrate surface topography. According ti the laser parameters (energy per pulse, pulse numbers) pattern morphology can be created. Therefore, textured surface filling by melted particles has been studies to minimize interface defaults and created mixed-mode failures for during plasma spray coatings. The drilling mechanisms have been evaluated by numerical modeling and experimental analysis. The pattern dimensions and heat affected zones has been identified. The laser treatment changes the microstructure locally.Oxydation tests have been performed to study the surface pre-tratments effects on oxide nature and mass gain rate. The damaging mechanisms ave been studied under isotherm and cyclic high temperature tests and also under creeping and thermo-mechanical fatigue tests. Grit-blasting change the natural oxides, limits life-span and bucking failure mode have been obeserved. Natural oxides have been analyzed for the textured substraes also but anchoring mechanism enables large life-span under high temperature tests. Mechanical applied stresses (constant and cyclic) validate the beneficial effects of patterned surfaces. The interface is stronger than the coating toughness and the patterns do not create early cracks under thermo-mechanical solicitations.
49

Autobiografische Erinnerungen an Ereignisse aus der Kindheit und Jugend: Ergebnisse einer Lebensspannenstudie mit älteren Menschen

Hillebrandt, Dirk 14 January 2003 (has links) (PDF)
Das autobiografische Gedächtnis findet als Thema der psychologischen Grundlagenforschung immer größere Aufmerksamkeit. Vorliegende Arbeiten haben zur differenzierten Charakterisierung des autobiografischen Wissensbestands in seiner Gesamtheit und der autobiografischen Erinnerungen als dessen Elemente beigetragen. Neben Fragen der Repräsentation liegt es nahe, Besonderheiten des autobiografischen Gedächtnisses über die Lebensspanne hinweg zu betrachten. Schwerpunkt der Analysen ist die Verteilung individueller Erinnerungen an Ereignisse über den gesamten Lebenslauf. Das zentrale Merkmal der Verteilung ist der relative Anstieg der Zahl von Erinnerungen im Zeitraum zwischen dem 10.und dem 30. Lebensjahr, vergleicht man diese mit der Zahl von Erinnerungen in den Lebensabschnitten direkt vor diesem und direkt im Anschluss an diesen Zeitabschnitt. Die Analyse dieser robusten und reliablen Besonderheit der Verteilung autobiografischer Erinnerungen - des bump - ist Gegenstand der vorliegenden empirischen Arbeit. Im Gegensatz zu bisherigen Studien galt unser Interesse aber nicht nur frei wählbaren Erinnerungen. Es stand vielmehr die Klasse der lebendigen autobiografischen Erinnerungen im Mittelpunkt, die innerhalb des autobiografischen Wissensbestands unterschiedlichen, aber in der individuellen Entwicklung über die Lebensspanne relevanten, von uns vorgegebenen Themen zuzuordnen sind (Arbeitsleben Beziehung zu Geschwistern, Beziehung zu Freunden und Bekannten, zusätzlich: Allgemeine lebendige Erinnerungen ohne thematische Bindung). Die berichteten Erinnerungen verteilten sich insgesamt in typischer Weise über die Lebensspanne. Unabhängig von themenspezifischen Aspekten zeigte sich auch in der vorliegenden Studie der bump in der Gesamtverteilung autobiografischer Erinnerungen über die Lebensspanne. Bei den themenspezifischen Verteilungen waren jedoch Abweichungen von der erwarteten Verteilungsform festzustellen. Der bump ließ sich bei den Themen Arbeitsleben und Freunde, Bekannte nur in abgeschwächter Form identifizieren, beim Thema Zwillinge war er dagegen auf einen früheren Zeitpunkt als erwartet datiert und sehr ausgeprägt. Die Verteilung im Themenblock Allgemein deckte sich weitgehend mit dem erwarteten Verteilungsmuster. Durch Einbindung in ein größeres Forschungsprojekt konnten die Verteilungen in den Themen Zwillinge und Arbeitsleben im Kontext relevanter biografischer Informationen weiter analysiert und z.T. auf lebensalters- und kontextgebundene Entwicklungen zurückgeführt werden. Die Ergebnisse der Studie werden im Hinblick auf ihre theoretischen Implikationen und ihre Bedeutung für nachfolgende Arbeiten aus einer entwicklungspsychologischen Perspektive diskutiert.
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Factors affecting the continuation of elderly people in a volunteeringservice

Li, Yuen-wah, Cecilla., 李婉華. January 1997 (has links)
published_or_final_version / Social Work / Master / Master of Social Sciences

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