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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.
31

A Study on Fuzzy Temporal Data Mining

Lin, Shih-Bin 06 September 2011 (has links)
Data mining is an important process of extracting desirable knowledge from existing databases for specific purposes. Nearly all transactions in real-world databases involve items bought, quantities of the items, and the time periods in which they appear. In the past, temporal quantitative mining was proposed to find temporal quantitative rules from a temporal quantitative database. However, the quantitative values of items are not suitable to human reasoning. To deal with this, the fuzzy set theory was applied to the temporal quantitative mining because of its simplicity and similarity to human reasoning. In this thesis, we thus handle the problem of mining fuzzy temporal association rules from a publication database, and propose three algorithms to achieve it. The three algorithms handle different lifespan definitions, respectively. In the first algorithm, the lifespan of an item is evaluated from the time of the first transaction with the item to the end time of the whole database. In the second algorithm, an additional publication table, which includes the publication date of each item in stores, is given, and thus the lifespan of an item is measured by its entire publication period. Finally in the third algorithm, the lifespan of an item is calculated from the end time of the whole database to its earliest time in the database for the item to be a fuzzy temporal frequent item within the duration. In addition, an effective itemset table structure is designed to store and get information about itemsets and can thus speed up the execution efficiency of the mining process. At last, experimental results on two simulation datasets compare the mined fuzzy temporal quantitative itemsets and rules with and without consideration of lifespans of items under different parameter settings.
32

Temporal Data Mining with a Hierarchy of Time Granules

Wu, Pei-Shan 28 August 2012 (has links)
Data mining techniques have been widely applied to extract desirable knowledge from existing databases for specific purposes. In real-world applications, a database usually involves the time periods when transactions occurred and exhibition periods of items, in addition to the items bought in the transactions. To handle this kind of data, temporal data mining techniques are thus proposed to find temporal association rules from a database with time. Most of the existing studies only consider different item lifespans to find general temporal association rules, and this may neglect some useful information. For example, while an item within the whole exhibition period may not be a frequent one, it may be frequent within part of this time. To deal with this, the concept of a hierarchy of time is thus applied to temporal data mining along with suitable time granules, as defined by users. In this thesis, we thus handle the problem of mining temporal association rules with a hierarchy of time granules from a temporal database, and also propose three novel mining algorithms for different item lifespan definitions. In the first definition, the lifespan of an item in a time granule is calculated from the first appearance time to the end time in the time granule. In the second definition, the lifespan of an item in a time granule is evaluated from the publication time of the item to the end time in the time granule. Finally, in the third definition, the lifespan of an item in a time granule is measured by its entire exhibition period. The experimental results on a simulation dataset show the performance of the three proposed algorithms under different item lifespan definitions, and compare the mined temporal association rules with and without consideration of the hierarchy of time granules under different parameter settings.
33

Don’t forget to remember – Prospective memory across the lifespan / Vergiss nicht Dich zu erinnern - Prospektives Gedächtnis über die Lebensspanne

Aberle, Ingo 15 December 2009 (has links) (PDF)
Prospective memory refers to the ability to remember to carry out delayed intentions, more precisely, to remember to initiate and execute an intended action at some point in the future. The development and progression of prospective memory across the lifespan is still heavily under debate. Only few studies have so far investigated prospective memory development in childhood, revealing an inconsistent pattern. In adulthood, studies in the laboratory and naturalistic studies showed paradoxical results with age deficits in the laboratory and age benefits in naturalistic tasks. Up to now, no conceptual model has been suggested to guide research on prospective memory development across the lifespan. Thus, the present work examined the effect of central factors from the multiprocess framework (McDaniel & Einstein, 2000) on the development of prospective memory in four different age-groups: pre-schoolers, school-age children, young and old adults. The first study explored the role of task motivation in age differences in prospective memory performance across the pre-school age-range. No main effect of age or motivation in prospective memory performance was found, yet a significant interaction, indicating that for younger children motivation or task importance may help allocating the available resources to the task elements of interest. Evidence from the second study indicated that 9-10 year old school children outperform 6-7 year old school children on a measure of prospective memory, and that retrieval-based factors (ongoing task absorption, cue salience, cue focality) systematically influenced performance. Of particular importance for possible developmental mechanisms was the finding of an age x cue focality interaction, suggesting that age effects may be modulated by cue focality. The third study examined the effect of task setting in a laboratory procedure and the effect of motivation in a naturalistic procedure on prospective memory performance in young and older adults. Results from the laboratory prospective memory procedure revealed significant age-related decline for irregular tasks but not for regular and focal tasks. In addition, in the naturalistic procedure, the age benefit was eliminated when young adults were motivated by incentives. Results from the present work indicated that already pre-school age children were able to remember to perform intended actions and this ability increased across school-age. In adulthood, the results revealed a decline with age on a pure performance level. Yet, older adults may be able to compensate for basic cognitive impairments if task conditions reduce the need for controlled attention. Furthermore, the present work suggest, that factors of the multiprocess framework may indeed affect age-differences in prospective memory performance throughout the lifespan, as cue focality and task importance were related to prospective memory development in children and adults. Thus, the multiprocess approach might serve as foundation for a lifespan theory of the development of prospective memory.
34

The relationship between short-term intraindividual variability and longitudinal intraindividual cognitive change in older adulthood: covariation and prediction of change

Bielak, Allison Anne Marie 01 August 2008 (has links)
This dissertation presents two studies of intraindividual variability in a longitudinal context to further explore the relationship between short-term intraindividual variability and longer-term cognitive change in older adults. A sample of 304 community-dwelling older adults initially aged 64-92 years completed between 1 to 6 waves of annual testing over a 5-year period. Participants completed an extensive battery of accuracy- and latency-based tests covering a wide range of cognitive complexity. The first study addressed the longitudinal nature of intraindividual variability over 3 years. Group-based increases in inconsistency were limited to the latter half of older adulthood (i.e., 75 years and older), but there were significant individual differences across the entire sample. The covariation relationships between change in cognition and change in inconsistency were significant across the one-year interval, and found to remain stable across both time and older age. For each additional unit increase in intraindividual variability, participants’ cognitive performance correspondingly declined. The strength of the coupling relationship however was stronger for fluid cognitive domains such as memory, reasoning, and processing speed, and variability based on moderately and highly complex tasks provided the strongest prediction. Building on these results suggesting that intraindividual variability is highly sensitive to even subtle changes in cognitive ability, the second study addressed the capacity of intraindividual variability to predict cognitive ability and other meaningful change outcomes 5 years later. Inconsistency at Wave 1 was particularly sensitive to changes reflecting the early behavioural characteristics of dementia, including episodic memory ability, cognitive status, and attrition. In each case, greater inconsistency at baseline was associated with a greater likelihood of being in a maladaptive group 5 years later. Mean rate of responding was a comparable predictor of change in most instances, but differences emerged according to the complexity of their derived tasks. Variability based on moderate to high cognitively challenging tasks appeared to be the most sensitive to longitudinal changes in cognitive ability, and was uniquely predictive of the rate of attrition compared to neuropsychological tasks. These findings are promising of the potential utility and applicability of intraindividual variability in understanding and predicting intraindividual cognitive change in older adulthood.
35

Lifespan Development: A Social-Cultural Perspective

ori@ashman.cc, Ori Ashman January 2006 (has links)
This thesis explores some of the social factors that may affect individuals as they age. A lifespan developmental perspective is employed in investigating the effects of societal aging stereotypes on will-to-live and risk-taking skills. Results suggest negative aging stereotypes may have deleterious effects on the elderly, but not young individuals in terms of will-to-live, but have no effect on risk-taking abilities. Furthermore, a cross-cultural analysis of Americans and Japanese reveals robust differences in self-concept between countries, which in turn partially mediate the effects of culture and age on control strategies. It appears culture and age may play important roles in determining individuals’ self-concept, motivation, and regulation of behavior. The first part of Study 1 examined whether stereotypes of aging contribute to decisions the elderly make about when to die. Elderly and young participants (n = 64) were subliminally primed with either negative or positive stereotypes of old age using a computer, and then responded to hypothetical medical situations involving potentially fatal illnesses. Consistent with my prediction, the aged participants primed with negative stereotypes tended to refuse life-prolonging interventions, whereas those primed with positive age stereotypes tended to accept the interventions. This priming effect did not emerge among the young participants for whom the stereotypes were less relevant. The results suggest that sociallytransmitted negative stereotypes of aging can weaken elderly will-to-live, or at the very least, willingness to pursue medical intervention. The second part of Study 1 examined whether the older adults demonstrate similar risk-taking skills to the younger adults, and whether this ability is preserved, even after exposure to age stereotypes. Sixteen young and 16 older participants were tested on a risk-taking decision task following exposure to subliminal aging stereotypes. In all conditions, both the old and young participants systematically and equivalently increased their willingness to take risks as risk level decreased. Furthermore, response times were an inverted U shape curve with slower response times recorded at the medium risk level and faster times as risk levels shifted up or down. The findings suggest the ability to make decisions based on risk level is maintained into old age. Study 2 investigated results reported by a number of studies finding that primary control remains stable in old age, is lower in Asian countries, and that secondary control increases in old age and is higher in Asian countries. I examined whether these patterns may be due to the mediating influence of an interdependent self-concept. In a sample of 557 young and older adults in Japan and the United States, primary and secondary control, age, and interdependence were studied. I found that interdependence partially mediated the influence of culture on secondary control and interdependence partially mediated the influence of age on both primary and secondary control. Findings suggest that interdependence is an important factor that should be considered in trying to understand the determinants of control crossculturally and developmentally.
36

The relationship between short-term intraindividual variability and longitudinal intraindividual cognitive change in older adulthood: covariation and prediction of change

Bielak, Allison Anne Marie 01 August 2008 (has links)
This dissertation presents two studies of intraindividual variability in a longitudinal context to further explore the relationship between short-term intraindividual variability and longer-term cognitive change in older adults. A sample of 304 community-dwelling older adults initially aged 64-92 years completed between 1 to 6 waves of annual testing over a 5-year period. Participants completed an extensive battery of accuracy- and latency-based tests covering a wide range of cognitive complexity. The first study addressed the longitudinal nature of intraindividual variability over 3 years. Group-based increases in inconsistency were limited to the latter half of older adulthood (i.e., 75 years and older), but there were significant individual differences across the entire sample. The covariation relationships between change in cognition and change in inconsistency were significant across the one-year interval, and found to remain stable across both time and older age. For each additional unit increase in intraindividual variability, participants’ cognitive performance correspondingly declined. The strength of the coupling relationship however was stronger for fluid cognitive domains such as memory, reasoning, and processing speed, and variability based on moderately and highly complex tasks provided the strongest prediction. Building on these results suggesting that intraindividual variability is highly sensitive to even subtle changes in cognitive ability, the second study addressed the capacity of intraindividual variability to predict cognitive ability and other meaningful change outcomes 5 years later. Inconsistency at Wave 1 was particularly sensitive to changes reflecting the early behavioural characteristics of dementia, including episodic memory ability, cognitive status, and attrition. In each case, greater inconsistency at baseline was associated with a greater likelihood of being in a maladaptive group 5 years later. Mean rate of responding was a comparable predictor of change in most instances, but differences emerged according to the complexity of their derived tasks. Variability based on moderate to high cognitively challenging tasks appeared to be the most sensitive to longitudinal changes in cognitive ability, and was uniquely predictive of the rate of attrition compared to neuropsychological tasks. These findings are promising of the potential utility and applicability of intraindividual variability in understanding and predicting intraindividual cognitive change in older adulthood.
37

The role of metal metabolism and heat shock protein genes on replicative lifespan of the budding yeast, Saccharomyces cerevisiae

2015 December 1900 (has links)
A variety of genes that influence aging have been identified in a broad selection of organisms including Saccharomyces cerevisiae (yeast), Caenorhabditis elegans (worms), Drosophila (fruit flies), Macaca Mulatta (rhesus monkeys), and even Homo sapiens. Many of these genes, such the TOR’s, FOXO’s, AKT’s, and S6K’s are conserved across different organisms. All of these genes participate in nutrient sensing networks. Other conserved genetic networks may similarly affect lifespan. In this thesis, I explored genes from an iron metabolism family and a heat shock protein (HSP) gene family that have been identified, but not confirmed, to influence lifespan. Yeast is a reliable model for mitotic (replicative) aging. Using yeast, I tested whether the FET-genes, encoding a family of iron importer-related genes, are required for mitotic lifespan. I also tested whether another family of genes, the yeast SSA HSP70- encoding genes, related to mammalian HSP70s, influence mitotic aging. I primarily used the replicative lifespan (RLS) assay, in which I measured the mitotic capacity of multiple FET and SSA yeast mutants. I hypothesize that aging occurs when iron transport is misregulated, which may lead to an over-reliance on HSPs for lifespan maintenance. The results presented in this thesis support the hypothesis. First, FET3 was primarily involved in lifespan maintenance under normal conditions (2% glucose), while FET5 was primarily involved in the cellular lifespan extension characteristic of caloric restriction (0.01% glucose), a known anti-aging intervention. In addition, SSA2 appeared to facilitate lifespan maintenance in the absence of FET4, while the presence of SSA1 limited lifespan length. That the aging genes identified in this study are involved in iron metabolism or heat stress suggests that protein aggregation or reactive oxidative species production are common processes through which these genes interact.
38

Desgaste de dressadores de ponta única fabricados com diamantes CVD e sua influência na rugosidade / Dressers wear tip only produced with diamonds CVD and its influence on roughness

Sakamoto, Alessandro Hiroshi [UNESP] 29 July 2016 (has links)
Submitted by ALESSANDRO HIROSHI SAKAMOTO null (alessandro.sakamoto@usiban.com.br) on 2016-09-06T20:05:51Z No. of bitstreams: 1 Dissertação Alessandro Hiroshi Sakamoto.pdf: 3320308 bytes, checksum: 596ed8870d27e3ad4f87b4094f030349 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-09-09T19:29:25Z (GMT) No. of bitstreams: 1 sakamoto_ah_me_bauru.pdf: 3320308 bytes, checksum: 596ed8870d27e3ad4f87b4094f030349 (MD5) / Made available in DSpace on 2016-09-09T19:29:25Z (GMT). No. of bitstreams: 1 sakamoto_ah_me_bauru.pdf: 3320308 bytes, checksum: 596ed8870d27e3ad4f87b4094f030349 (MD5) Previous issue date: 2016-07-29 / O processo de retificação é uma das mais importantes operações usadas para a obtenção de peças com altas precisões, sendo a mesma responsável pelo aumento nos custos finais dos produtos. Para que as operações possam ser realizadas com o máximo de eficiência é importante que o rebolo – ferramenta utilizada na operação de retificação – seja dressado em intervalos frequentes para a remoção dos grãos gastos e manter o perfil de sua superfície. A dressagem apresenta várias técnicas, com diversas ferramentas, mas para a maioria dos rebolos, cujos quais são do tipo convencional, a dressagem realizado com a ferramenta de ponta única de diamante é a mais utilizada. Com isso o monitoramento se torna então uma questão para a qualidade da peça, onde o aperfeiçoamento das técnicas de retificação deve ser utilizada para um melhor aproveitamento do rebolo. Foram verificados a geometria de cada formato do diamante presente no dressador de ponta única, sendo a forma geométrica do dressador piramidal e trapezoidal. Neste trabalho foi avaliado a rugosidade da peça, após a retificação da peça em aço VP 80, sendo o rebolo dressado com dois tipos de dressadores com diamantes sintéticos CVD um com o tipo piramidal e trapezoidal. As medições de rugosidade foram realizadas em intervalos de 20, 70 e 120 passadas e diferentes parâmetros Ud (igual a 1 e 5), e após cada etapa realizada o rebolo era dressado e novamente era realizada a retificação da peça e, assim, sucessivamente para os demais ensaios, onde foram coletados os dados dos ensaios realizados e armazenados para avaliação de cada etapa que foi realizada. Observou que no decorrer dos ensaios os resultados apresentaram variações na rugosidade para ambos os dressadores e para os diferentes parâmetros de Ud. Baseado nos dados coletados observou que dressador com o formato trapezoidal apresentou menor rugosidade na peça após os intervalos de 70 e 120 passadas e o piramidal só apresentou menor rugosidade no intervalo de 20 passadas, sendo assim os ensaios mostram que o diamante com o formato trapezoidal tendo sua área de recobrimento maior que piramidal, e o parâmetro de Ud maior deixa o rebolo menos agressivo. / The grinding process is one of the most important operations used for obtaining high precision workpieces being such process responsible for the increase on the final product cost. In order to perform at its high efficiency it is important that the grinding wheel –a tool used in the grinding process – be dressed at frequent intervals for the removal of the worn grains and maintenance of the profile of its surface. The dressing allows several techniques with diversified tools but once most grinding wheels are the conventional types the dressing performed with a single point diamond tool is the most commonly used. Due to such a feature, monitoring becomes a relevant aspect for the quality of the workpiece, where the improvement of the grinding wheel rectification techniques must be used for majoring the use of the grinding wheel. It was verified the geometry of every diamond shape presented in the single point dresser with pyramidal and trapezoidal shapes. In this work it was evaluated the roughness of the workpiece after the rectification with VP 80 steel being the grinding wheel dressed with two kinds of CVD synthetic diamond dressers, both presenting pyramidal and trapezoidal shapes.The roughness measurement was carried out at 20, 70 and 120 spinning intervals and different Ud parameters (equal 1 and 5) and after every stage the grinding wheel was dressed and once again the rectification of the workpiece was performed and that was continuously done with the remaining essays so that the essays data were collected and stored for the evaluation of each stage. It was observed that during the essays process the results presented variations towards both dressers and towards the different Ud parameters. Based on the collected data it became clear that the trapezoidal dresser shape showed less roughness in the workpiece at the 70 and 120 spinning intervals and the pyramidal one only presented less roughness at the 20 spinning interval which leads to the conclusion that once the trapezoidal shape diamond has a wider covered surface than the pyramidal shape diamond, the bigger Ud parameter makes the grinding wheel less aggressive.
39

Vliv kvality artikulačních UHMWPE vložek na životnost kloubních náhrad / The influence of the quality of articulation UHMWPE inserts on the lifetime of joint replacements

Fulín, Petr January 2016 (has links)
This thesis focuses on the introduction with the problems of high molecular weight polyethylene (UHMWPE) in orthopedics in the first part. It discusses the history, properties and processes that lead to the failure of UHMWPE joint replacement components. The experimental part validates the hypotheses expressed. It acquaints readers with the experimental verification of the effect of different types of sterilization on the oxidative stability of laboratory prepared samples and explanted UHMWPE joint replacement components using methods of infrared microscopy, electron spin resonance, mechanical tests and tests of microhardness. Other experimental measurements on a large set of explanted components of hip and knee total joint replacements validates the hypothesis that the amount of oxidative damage affects the lifespan of joint replacements. The third part of the experimental study maps the degree of oxidative damage in different places of the hip and knee joint replacements. In the final part we experimentally demonstrate the fact that the rate of oxidative damage has an effect on supramolecular structure of the UHMWPE. From the above experiments are concluded clearly defined recommendations for clinical practice, which should lead to extend the lifespan of total joints replacements in orthopaedics....
40

Le développement de la régulation émotionnelle de l'adolescence au vieillissement : application d'un modèle dynamique des affects en lien avec la personnalité / The development of emotional regulation from adolescence to aging : application of a dynamic model of affects related to the personality

Le Vigouroux, Sarah 20 June 2016 (has links)
Dans la littérature, un effet de positivité, se traduisant par une augmentation des affects positifs et/ou une diminution des affects négatifs lors de la période de l’âge adulte, est identifié. Plusieurs modèles sont proposés pour tenter d’expliquer cet effet de positivité. Ils portent sur différents aspects des individus, du développement cognitif et de la régulation affective. Ce travail de thèse s’appuie sur quatre modèles : les théories de sélectivité socioémotionnelle (Löckenhoff & Carstensen, 2004), de sélection-optimisation-compensation en régulation émotionnelle (Urry & Gross, 2010), de l’intégration dynamique (Labouvie-Vief, 2003) et celle de l’intégration des forces et des vulnérabilités (Charles, 2010). L’évolution de trois processus est ciblée : la sélection, l’efficacité et la temporalité d’utilisation des stratégies de régulation. Deux hypothèses sont prises en compte. L’hypothèse développementale est qu’avec l’avancée en âge les individus acquerraient une expertise dans l’utilisation des stratégies, qui serait visible sur ces trois processus de régulation. L’hypothèse différentielle se centre sur les différences individuelles dans l’effet de positivité et sur le développement de l’expertise dans la régulation affective. Les résultats obtenus mettent en évidence un effet de positivité général. Cet effet de positivité s’explique par le développement d’une expertise, mais qui n’est la même pour tous les individus. En effet certains vont cibler la réduction des affects négatifs pendant que d’autres ciblent l’augmentation des affects positifs. Dans l’ensemble, ces résultats mettent en évidence un basculement hédonique des objectifs de régulation affective. / In literature a positivity effect, can be defined as increased positive affect and / or decrease negative affect in adulthood, is identified. Several models try to explain the positivity effect for different aspects of individuals, the cognitive development and emotional regulation. This work thesis focuses on four models: the socioemotional selectivity theory (Löckenhoff & Carstensen, 2004), selection-optimization-compensation in emotional regulation (Urry & Gross, 2010), the dynamic integration theory (Labouvie-Vief, 2003) or that the integration of strengths and vulnerabilities (Charles, 2010). Especially concerning the development of three processes related to emotional regulation: selection, efficiency and temporally use of regulation strategies. Two hypotheses are considered. The developmental hypothesis is individuals develop expertise with aging in the use of strategies. That would be visible on the emotional regulation processes. The differential hypothesis focuses on individual differences in the positivity effect and the development of expertise in emotional regulation presented by the previous hypothesis. The results reveal one pattern of positivity effect whatever personality characteristics. This positivity effect can be explained by a development of expertise but while is not the same for everyone. Overall, the results show a hedonic shift of emotional regulation aims. The discussion of results highlights the relevance of the differential approach in the study of the developmental phenomenon to positivity effect.

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