Dissertations / Theses: 'Aging of the lens'

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Bergbauer, Katrina L. "Laser raman spectroscopic studies of ocular lens aging and cataractogenesis." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/30031.

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Siik, S. (Seppo). "Lens autofluorescence:in aging and cataractous human lenses. Clinical applicability." Doctoral thesis, University of Oulu, 1999. http://urn.fi/urn:isbn:9514252675.

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Abstract This study was carried out to investigate in vivo the changes of the human lens autofluorescence (AF) with aging and cataractogenesis. Measurements were performed in the blue-green AF range (495 nm/520 nm) using a fluorometer designed, built and now clinically tested in our department. 43 random eyes of 43 healthy volunteers aged 6-86 years, five of each decade, were studied for effects of aging and 84 eyes of 84 patients with cortical, nuclear, posterior subcapsular or mixed lens opacities were studied for differences of various cataract types. The results were compared with the back light scatter values obtained by the commercially available Interzeag Lens Opacity Meter 701. Also AF and back light scatter of the lens were measured from 122 smoking males aged 57 to 76 years who participated in a cancer prevention study. The results were compared with the widely used subjective lens opacities classification system, LOCS III. In addition data was collected from 30 randomly chosen eyes of as many subjects with varying degrees of yellow-brown lens coloration in an otherwise healthy eye. We studied the influence of lens yellowing expressed by means of lens AF on visibility of retinal nerve fiber layer in black-and-white images. Lens AF profile consists of anterior and posterior peaks and a central plateau. The height of the anterior peak was used as a measure of the maximum AF value. The square root of the ratio between the posterior and the anterior AF peaks was used for estimating the lens transmission. Our technique was highly reproducible. The coefficient of variation was 3.9% for maximum AF and 2.9% for the lens transmission index. Both the maximum AF and light scatter were exponentially increased with age (r = 0.95 and 0.94, respectively; p < 0.0001). According to the regression line of AF begins to increase in early childhood. It appears by extrapolation to be absent at birth. In contrast light scatter in the lens was present even in young children. The lens transmission for blue-green light, determined from the lens AF curve, was almost unchanging with age up to 60 years. Thereafter it decreased rapidly and the interindividual variation increased.In cataractous lenses the mean AF and scatter values differed statistically significantly from those of age matched healthy controls. The highest AF values were measured in nuclear cataracts where AF was also related to visual acuity and an increasing yellow-brown colour of the nucleus. About half of the total variation of the transmission index values could be accounted for by changes in nuclear colour as assessed by the LOCS III grading system. The transmission index provided a more precise prediction about nuclear colour and opalescence than age or light scatter did. In cortical cataracts the AF curve was low and flattened and the maximum AF value was significantly lower than in the age matched control eyes. The highest light scatter values were measured from cortical cataracts, but the correlation between LOCS III cortical grades and light scatter values was rather weak. Posterior subcapsular cataracts cannot be quantified either with AF or with light scatter measurements. Lens yellowing, expressed as lens AF, had an actual effect on retinal nerve fiber layer visibility. AF measurements provided a better prediction about the visibility score than age or visual acuity did. The results of the present study indicate that the lens autofluorescence measurement may be a useful additional tool together with a subjective grading system in the follow-up of optical changes occurring in the nuclear region of the lens.

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Barron, Brent Christian. "Characterization of normal aging and cataractous processes in the eye lens by laser raman spectroscopy." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/30052.

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Li, Yi. "Cell proliferation as a biomarker of aging and effect of caloric restriction in mouse lens /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/6328.

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Hawse, John R. "Identification and functional characterization of cataract-specific gene expression changes reveals important pathways for human lens maintenance, aging and disease." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3365.

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Thesis (Ph. D.)--West Virginia University, 2004.
Title from document title page. Document formatted into pages; contains x, 201 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 185-201).

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O'Hanlon, Kelsie C. "Medieval Views on Aging and Their Modern Implications: Analyzing Chaucer's Pardoner Through the Lens of a Second Mirror-Stage." Ohio Dominican University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=odu1512578183523566.

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Mizdrak, Jasminka. "Human lens chemistry: UV filters and age-related nuclear cataract." Australia : Macquarie University, 2007. http://hdl.handle.net/1959.14/16855.

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"A thesis submitted in partial fulfillment of the requirements for the award of the degree of Doctor of Philosophy".
Thesis (PhD) -- Macquarie University, Division of Environmental and Life Sciences, Dept. of Chemistry and Biomolecular Sciences, 2007.
Bibliography: p. 243-277.
Introduction -- A convenient synthesis of 30HKG -- Facile synthesis of the UV filter compounds 30HKyn and AHBG -- Synthesis, identification and quantification of novel human lens metabolites -- Modification of bovine lens protein with UV filters and related metabolites -- Effect of UV light on UV filter-treated lens proteins -- Conclusions and future directions.
The kynurenine-based UV filters are unstable under physiological conditions and undergo side chain deamination, resulting in α,β-unsaturated carbonyl compounds. These compounds can react with free or protein bound nucleophiles in the lens via Michael addition. The key sites of the UV filters kynurenine (Kyn) and 3-hydroxykynurenine (3OHKyn) modification in human lenses include cysteine (Cys), and to a lesser extent, lysine (Lys) and histidine (His) residues. Recent in vivo studies have revealed that 3-hydroxykynurenine-O-β-D-glucoside (3OHKG) binds to Cys residues of lens crystallins in older normal human lenses. As a result of this binding, human lens proteins become progressively modified by UV filters in an age-dependent manner, contributing to changes that occur with the development of age-related nuclear (ARN) cataract. Upon exposure to UV light, free UV filters are poor photosensitisers, however the role of protein-bound species is less clear. It has been recently demonstrated that Kyn, when bound to lens proteins, becomes more susceptible to photo-oxidation by UV light. Therefore, the investigation of 3OHKG binding to lens proteins, and the effect of UV light on proteins modified with 3OHKG and 3OHKyn, were major aims of this study. As a result of the role of these compounds as UV filters and their possible involvement in ARN cataract formation, it is crucial to understand the nature, concentration and modes of action of the UV filters and their metabolites present in the human lenses. Therefore, an additional aim was to investigate human lenses for the presence of novel kynurenine-based human lens metabolites and examine their reactivity.--As 3OHKG is not commercially available, to conduct protein binding studies, an initial aim of this study was to synthesise 3OHKG (Chapter 2). Through the expansion and optimisation of a literature procedure, 3OHKG was successfully synthesised using commercially available and inexpensive reagents, and applying green chemistry principles, where toxic and corrosive reagents were replaced with benign reagents and solvent-free and microwave chemistry was used. A detailed investigation of different reaction conditions was also conducted, resulting in either the improvement of reaction yields or reaction time compared to the literature method. Applying the same synthetic strategy, and using key precursors from the synthesis of 3OHKG, the UV filters 3OHKyn and 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid-O-β-D-glucoside (AHBG), were also successfully synthesised (Chapter 3).
Chapter 4 describes the investigation of both normal and cataractous human lenses in an attempt to identify novel human lens metabolites derived from deaminated Kyn and 3OHKyn (Chapter 4, Part A). Initially, 4-(2-aminophenyl)-4-oxobutanoic acid (AHA), glutathionyl-kynurenine (GSH-Kyn), kynurenine yellow (Kyn yellow), 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid (AHB), glutathionyl-3-hydroxykynurenine (GSH-3OHKyn) and 3-hydroxykynurenine yellow (3OHKyn yellow) were synthesised and human lenses were examined for their presence. AHA and AHB were synthesised from similar precursors to those used in the synthesis of 3OHKG, while the GSH adducts and yellow compounds were synthesised from Kyn and 3OHKyn via base induced deamination. Following isolation and structural elucidation, AHA, AHB and GSH-Kyn were confirmed as novel human lens metabolites. They were quantified in low pmol/mg lens (dry mass) levels in normal and cataractous lenses of all ages, while GSH-3OHKyn, Kyn yellow and 3OHKyn yellow were not detected. In contrast to AHA, the lens metabolites AHB, GSH-Kyn and GSH-3OHKyn were found to be unstable at physiological pH. The spectral properties of these compounds suggest that they may act as UV filters. --Chapter 4 (Part B) also describes the identification and characterisation of a novel human lens UV filter, cysteinyl-3-hydroxykynurenine -O-β-D-glucoside (Cys-3OHKG). An authentic standard was synthesised via Michael addition of cysteine to deaminated 3OHKG. Cys-3OHKG was detected in low pmol/mg lens (dry mass) levels in normal lenses only after the 5th decade of life and was absent in cataractous lenses. Cys-3OHKG showed rapid decomposition at physiological pH.
Chapter 5 describes the identification and quantification of amino acids involved in covalent binding of 3OHKG to lens proteins. Model studies with bovine lens proteins and 3OHKG at pH 7.2 and 9.5 were undertaken. The amino acid adducts were identified via total synthesis and spectral analysis, and subsequently quantified upon acid hydrolysis of the modified lens proteins. Under both pH conditions, 3OHKG was found to react with lens proteins predominantly via Cys residues with low levels of binding also detected at Lys residues. Comparative studies with Kyn (pH 9.5) and 3OHKyn (pH 7.2 and 9.5) resulted in modified lens proteins at Cys residues, with only minor modification at Lys residues at pH 9.5. The extent of modification was found to be significantly higher at pH 9.5 in all cases. His adducts were not identified. 3OHKG-, Kyn- and 3OHKyn-modified lens proteins were found to be coloured and fluorescent, resembling those of aged and ARN cataractous lenses. In contrast, AHB and AHA, which can not form α,β-unsaturated carbonyl compounds, resulted in non-covalent modification of lens proteins. AHB may contribute to lens colouration and fluorescence as further reactions of this material yielded species that have similar characteristics to those identified from 3OHKyn modification. These species are postulated to arise via auto-oxidation of the o-aminophenol moiety present in both 3OHKyn and AHB.--In Chapter 6, the potential roles of 3OHKG and 3OHKyn, and the related species AHA and AHB, in generating reactive oxygen species and protein damage following illumination with UV light was examined. The UV filter compounds were examined in both their free and protein-bound forms. Kyn-modified proteins were used as a positive control. Exposure of these compounds to UV light (λ 305-385 nm) has been shown to generate H2O2 and protein-bound peroxides in a time-dependent manner, with shorter wavelengths generating more peroxides. The yields of peroxides were observed to be highly dependent on the nature of the UV filter compound and whether these species were free or protein bound, with much higher levels being detected with the bound species. Thus, protein-bound 3OHKyn yielded higher levels of peroxide than 3OHKG, with these levels, in turn, higher than for the free UV filter compounds. AHB-treated lens proteins resulted in formation of low but statistically significant levels of peroxides, while AHA-treated lens proteins resulted in insignificant peroxide formation. The consequences of these photochemical reactions have been examined by quantifying protein-bound tyrosine oxidation products (3,4-dihydroxyphenylalanine [DOPA], di-tyrosine [di-Tyr]) and protein cross-linking. 3OHKG-modified proteins gave elevated levels of di-Tyr, but not DOPA, whereas 3OHKyn-modified protein gave the inverse. DOPA formation was observed to be independent of illumination and most likely arose via o-aminophenol auto-oxidation. AHB- and AHA-treated lens proteins resulted in statistically insignificant di-Tyr formation, while a light independent increase in DOPA was observed for both samples. Both reducible (disulfide) and non-reducible cross-links were detected in modified proteins following illumination. These linkages were present at lower levels in modified, but non-illuminated proteins, and absent from unmodified protein samples.
This work has provided an optimised synthetic procedure for 3OHKG and other lens metabolites (Chapters 2 and 3). Four novel lens metabolites have been identified and quantified in normal and cataractous human lenses (Chapter 4). Subsequent experiments, described in Chapter 5, identified the major covalent binding sites of 3OHKG to lens proteins, while AHA and AHB showed non-covalent binding. Further work described in Chapter 6 showed that protein-bound 3OHKG, Kyn and 3OHKyn were better photosensitisers of oxidative damage than in their unbound state. Together, this research has provided strong evidence that post-translational modifications of lens proteins by kynurenine-based metabolites and their interaction with UV light appear, at least in part, responsible for the age-dependent colouration of human lenses and an elevated level of oxidative stress in older lenses. These processes may contribute to the progression of ARN cataract.
Mode of access: World Wide Web.
xxxix, 308 p. ill. (some col.)

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Sparks, Cassandra Renee. "Investigating General Aging Expectations, Self-Perceptions for Aging and Attributions for Aging among Physically Active and Less Active Adults." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20243.

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This thesis, comprising two studies, investigated whether negative expectations and self-perceptions relating to the aging process are associated with less physical activity (Study 1), and whether less active adults are likely to report age as a cause for physical activity failure than more active adults (Study 2). Using Sarkisian et al.’s (2002) Expectations Regarding Aging (ERA-38) survey, Study 1 first developed reliable and valid sub-factors for constructs relating to general aging expectations (GAE) and aging self-perceptions (ASP) by conducting exploratory factor analyses on 167 adults (M age = 59.5). Results revealed three acceptable GAE sub-factors relating to satisfaction/contentment, physical function and cognitive function, and three ASP sub-factors pertaining to functional, social, and sexual health. Subsequent MANOVA analyses showed that active adults reported higher GAE for satisfaction/contentment and cognitive function than less active adults. Regression analyses revealed that physical activity levels positively predicted satisfaction/contentment and physical function expectations among 45-54 yr olds. In Study 2, 177 adults (M age = 60.1) completed our Causal Dimension Scale for Aging (CDSA) and a survey asking whether age was a likely cause of failure in various physical activity contexts. Responses on the CDSA were used to validate ‘General Attributions towards Age’ (GATA), a measure which captured how adults view the aging effects. Subsequent analyses of variance determined that GATA interacted with physical activity status (active, less active) to influence the reported likelihood of age as a cause for failure. Less active adults with stable/uncontrollable GATA reported greater likelihood of age as a cause for failure than all other groups in gym, recreational/community program, and unstructured/spontaneous activity settings. Separate age group analyses indicated that these trends were pronounced in an unstructured/spontaneous activity setting for 45-54 yr olds, and in a generally recently inactive scenario for 55-64 yrs.

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Obrenovich, Mark E. "Investigations Into the Mechanisms of Vitamin C Uptake in Rodent and Human Lens Epithelial Cells." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1212629235.

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Elkins, Jeananne Sharp. "Diverse facilities, aging residents| Assisted living through the lens of the 2010 National Survey of Residential Care Facilities." Thesis, The Texas A&M University System Health Science Center, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3587509.

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In the late 1980's assisted living emerged as a self-proclaimed new style of providing long-term care and supportive services. Assisted living as espoused by its early proponents and by industry leaders embodied certain specific philosophical tenets, such as dignity, autonomy, meeting scheduled and unscheduled needs and aging in place, in their daily operations. These tenets distinguished assisted living from other forms of institutional care such as nursing home care. In the past twenty years the assisted living industry has matured and grown substantially. However, despite the maturing of the industry and the general agreement on the basic tenets little is known about the degree to which the industry embodies these principles.

In addition public policy and consumer preferences have grown in their focus on substituting assisted living for nursing home care. Moreover, the degree to which assisted living can and does substitute for nursing home care has been largely unexamined. Elder care advocates and researchers have more and more called attention to the increasing acuity level of assisted living residents.

This study consists of three related components, each of which will broaden the understanding of current assisted living facilities and their residents. The first study examines person environment fit in assisted living. Lawton's theory of person environment fit, has largely defined the construction and physical environment of assisted living since the 1980's. Changes in Lawton's theory were proposed by Guiata and Jones in the Journal of the American Medical Association in 2012 in reaction to the increased level of dementia in assisted living residents. A third non-theoretical analysis using exploratory factor is designed assist with development of new constructs in person environment fit theory. The second study examines changes in assisted living facilities and residents from 1999 to 2010. This study uses the only two national surveys of assisted living, The 1999 National Survey of Assisted Living and the 2010 National Survey of Residential Care Facilities. This study will examine both facility level and resident level characteristics to explicate resident acuities and to examine the degree to which facilities are accommodating these acuities. The third study examines facility characteristics associated with discharge of residents from assisted living facilities. Understanding resident discharge from assisted living will give a better understanding how assisted living facilities meet scheduled and unscheduled needs of residents as well as embody the philosophical concept of aging in place.

The contribution of this research is improved understanding of the current assisted living facilities and residents and better understand the importance of facility characteristics in person environment fit and in aging in place. This contribution is significant because assisted living residents are a vulnerable population with no protection under federal statutes and limited protection in most states. If indeed, as advocates and researchers assert, assisted living residents mirror nursing home residents in acuity then this research will assist with developing policies to protect this vulnerable population.

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Derham, Barry K. "The effects of ageing on #alpha#-crystallin, a molecular chaperone." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325297.

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Martineau, Aurélien. "Les immigrés au seuil du grand âge : analyse des parcours de vieillissement et de fin de vie dans les territoires de vie des migrants." Thesis, Angers, 2018. http://www.theses.fr/2018ANGE0052/document.

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Vieillir immigré est devenu une situation commune à un nombre grandissant de personnes en France. En 2015, près d’1,5 million de personnes immigrées étaient âgées de 60 ans et plus. La constante augmentation du nombre d’immigrés âgés constitue une question sociale et politique en France, ce qui a été confirmé tant par les récents travaux de l’Assemblée nationale que par l’avancée des connaissances scientifiques. Le nombre de travaux produits sur des territoires différents, là où les migrants âgés sont plus ou moins présents démographiquement reste encore aujourd’hui restreint. Face à ce constat, l’objectif de cette thèse par articles est de proposer une lecture territoriale et gérontologique de la vieillesse en migration. Deux terrains d’étude ont été retenus dans le cadre du projet doctoral (premièrement, les villes d’Angers et de Cholet en Maine-et-Loire et deuxièmement, la Ville de Montreuil en Seine-Saint-Denis). Les terrains de recherche ont été l’occasion d’analyser les conditions de vieillissement des personnes immigrées dans des contextes spatiaux différents (analyse des données territoriales et du discours des acteurs médico-sociaux, associatifs et politiques intervenants auprès des immigrés vieillissants). Dans la continuité, une analyse des récits biographiques d’un échantillon de migrants âgés résidant en Maine-et-Loire a été effectuée pou mettre en exergue les enjeux sociaux et spatiaux structurant les expériences de vieillissement des immigrés. Les résultats de recherche produits témoignent de la nécessité d’appréhender l’hétérogénéité de ces publics et d’étudier leurs besoins en regard de leurs parcours et des espaces qui structurent leur (fin de) vie
In France, getting old as an immigrant became a condition shared by a growing number of people. In 2015, about 1.5million of immigrants are 60years old or more. In France, the constant increase in the number of elderly immigrants represents a social and political issue, a fact confirmed by the recent works of the national assembly as well as by the development of scientific research. Nonetheless, the diversity of studies dealing with different territories inhabited by elderly immigrants remains limited. Consequently, this thesis (structured around several scientific articles) aims at proposing a representation of the “migrating elderly”, articulating a territorial and gerontological approach. Two different territories were taken into consideration: Angers andCholet (Maine-et-Loire), and Montreuil (Seine-Saint-Denis).This selection provided the opportunity to analyse the aging conditions of migrating population which evolve according to different spatial contexts. In this study, we considered territorial data, medico-social accounts, as well as the work of associations and political interventions to elderly immigrants.In addition, biographical facts and stories from as ample of elderly migrants in Maine-et-Loire were analysed to highlight the political and social issues that structure the aging conditions of immigrants.The result of this work proves that it is still essentia lto take into account the heterogeneity of these populations. It also underlines the importance of understanding their needs in terms of their own life journeys (and the end of it) which is inextricable of the territory they occupy

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DAI, ZHENYU. "PROTEIN CROSSLINKING BY THE MAILLARD REACTION WITH ASCORBIC ACID AND GLUCOSE." Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1184176746.

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Kulkarni, Priyanka Prashant. "Use of non Saccharomyces yeast strains coupled with ultrasound treatments as a novel technique to accelerate aging over lees of red wines and its repercussion in sensorial parameters." Master's thesis, ISA/UL, 2014. http://hdl.handle.net/10400.5/8636.

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Mestrado Vinifera EuroMaster - Instituto Superior de Agronomia
Ageing over lees has long been considered to benefit the overall quality of wine, enhancing the body and mouthful as well as sensorial complexity, color stability. Despite of all the positive attributes conferred by this technique, it is a complex process which could last up to years and is affected by several variables of different nature and complexities. This process has several economic impacts representing large investments for all producers to store the wines in cellars as well as the wine maker has to bear the potential risk associated with the organoleptic and microbiological alterations in the wines. Thus, it is important for the winemakers to optimize the time of ageing on lees. Further more in today’s fiercely competitive market it is reasonable to develop new strategies and techniques to accelerate the ageing over lees process, shorten the storage time and achieve better quality. In this study two novel techniques: use of non Saccharomyces strains coupled with ultrasound treatment were tested to see their efficiency for accelerating aging over lees. The combined effects of the techniques were tested to see their impacts on the polysaccharide release and on the organoleptic properties of red wine. Release of polysaccharides was analyzed by HPLC-RI. Anthocyanins and aroma compounds were analyzed by using HPLC-PDAD/ESI-MS, GC-FID respectively. Also Color and Total Phenolic Index were recorded periodically along the experiment. Results showed that ultrasound treatment is a reliable technique for shortening the ageing on lees process by strongly increasing the concentration of polysaccharides released into the wine after only two weeks treatment and without adversely affecting the sensorial quality of the wine. Additions of sand as an abrasives agent increased the polysaccharide release. Furthermore the non Saccharomyces strains of Schizosaccharomyces pombe, Saccharomyces ludwigii and Brettanomyces showed better results with regards to the amount of polysaccharide release compared to the control Saccharomyces strains. Interesting results with Brettanomyces were observed, as the use of this particular strain did not impart any off flavors to the wine. This can be explained by the use of lyophilized strains used in this study which were dosed in the wine to carry out the aging over lees. Ultrasonic treatment coupled with aging over lees resulted in reduction of anthocyanin content of the wine and also effected the aroma compounds.In conclusion this study illustrated the use of Ultrasounds and Non Saccharomyces strains as novel techniques for aging over lees, however more research in this field is required to study the clear effects on ultrasounds on the chemical composition of wine before replicating the application on a large scale production

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Calahorrano, Peña Lena Teresa [Verfasser]. "Essays on population aging and the political economy of immigration / Lena Teresa Calahorrano Pena." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2012. http://d-nb.info/1021514802/34.

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Bourdeau, Isabelle. "Les prédicteurs de la reprise des activités des personnes âgées après un séjour en unité de réadaptation fonctionnelle intensive." Mémoire, Université de Sherbrooke, 2007. http://savoirs.usherbrooke.ca/handle/11143/2523.

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The objective of this study was to explore which personal and environmental variables are the best predictors of reintegration to normal living in older adults discharged from an in-patient rehabilitation unit. More than fifteen biopsychosocial characteristics of 94 people over 60 years old were evaluated with reliable and valid tests a few days before discharge from rehabilitation. The participants' reintegration to normal living was evaluated three months later (n=86) with the Reintegration to Normal Living Index. From multivariate regression analyses, functional independence, balance, grip strength and general well-being are the best predictors and explain 26% and 27% of the variance in reintegration to normal living. This study suggests that by increasing efforts to maximize functional independence, balance, grip strength and well-being, rehabilitation professionals can expect older adults to achieve a greater degree of participation in their activities and social roles and maybe contribute to their quality of live.

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Aguiar, Veiga Roberto Gomes de. "Computational insights into the strain aging phenomenon in bcc iron at the atomic scale." Thesis, Lyon, INSA, 2011. http://www.theses.fr/2011ISAL0084/document.

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Le vieillissement statique est un concept important dans la métallurgie qui se réfère à un durcissement de la matière ayant subi une déformation plastique et est ensuite vieilli pendant une certaine période de temps. La théorie proposée dans les années 1940 par Cottrell et Bilby explique ce phénomène comme étant causé par l'épinglage des dislocations par les impuretés (par exemple, les atomes de carbone en solution solide) qui migrent au voisinage du défaut de ligne. Au cours de ce travail de thèse, le mécanisme atomistique responsable du phénomène du vieillissement statique dans le fer alpha a été étudié par des simulations numériques. Etant donné que la diffusion à l'état solide se déroule lentement, l'utilisation de la dynamique moléculaire à basse température (lorsque l'effet du champ de contraintes sur la dislocation de diffusion du carbone est plus prononcé) a été évitée, et nous avons utilisé préférentiellement le couplage de la statique moléculaire avec le Monte-Carlo cinétique atomistique. Trois points principaux ont été abordés dans cette thèse: (i) l'effet du champ de contraintes d'une dislocation coin ou vis sur un atome de carbone qui diffuse à proximité, (ii) la diffusion de l'atome de carbone dans le cour de la dislocation («pipe diffusion»), et (iii) la distribution d'équilibre des atomes de carbone dans une atmosphère de Cottrell. Le principal effet du champ de contrainte de la dislocation à l'extérieur du coeur est de biaiser la diffusion de l'impurité, de sorte que certains sauts (transitions) deviennent plus probables que d'autres. Cet effet va conduire aux premiers stades de la formation de l'atmosphère de Cottrell, lorsque l'interaction mutuelle entre atomes de carbone est négligeable. Au cœur de la dislocation, comme prévu, nos résultats indiquent que le carbone diffuse plus vite que dans le volume. La concentration de carbone dans le voisinage d'une dislocation coin ou vis a été modélisée par une approche de physique statistique en utilisant les énergies de liaison calculées par la statique moléculaire. Cette approche est en bon accord avec les données expérimentales
Static strain aging is an important concept in metalurgy that refers to the hardening of a material that has undergone plastic deformation and then is aged for a certain period of time. A theory proposed in the late 1940s by Cottrell and Bilby explains this phenomenon as being caused by the pinning of dislocations by impurities (e.g., carbon atoms in solid solution) that migrate to the vicinity of the line defect. In the course of this PhD work, the atomistic mechanism behind the static strain aging phenomenon in bcc iron has been studied by means of computer simulations. Given the fact that diffusion in the solid state proceeds slowly, thus preventing the use of molecular dynamics at low temperatures (when the effect of the dislocation stress field on carbon diffusion is more pronounced), we have preferentially employed a method coupling molecular statics with atomistic kinetic Monte Carlo. Three major points have been addressed by this thesis: (i) the effect of the stress field of an edge or screw dislocation on a carbon atom diffusing nearby; (ii) the diffusion of a carbon atom in the tight channel found in the dislocation core (pipe diffusion); and (iii) the equilibrium carbon distribution in a Cottrell atmosphere. The main effect of the dislocation stress field outside the dislocation core consists of biasing carbon diffusion, such that some transitions become more likely than others. This effect is expected to drive the early stages of Cottrell atmosphere formation, when the mutual interaction between carbon atoms is negligible. Right in the dislocation core, as expected, carbon was seen to diffuse faster than in the bulk. Carbon concentration in the neighborhood of an edge or a screw dislocation was modeled by an approach based in statistical physics using the binding energies calculated by molecular statics, revealing a good agreement with experimental data obtained by atom probe techniques

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Torrente, Giulio. "Étude des mécanismes de vieillissement et impact sur les performances dans les mémoires Flash NOR 40nm." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT029/document.

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La technologie Flash représente aujourd’hui la mémoire non-volatile de référence dans plusieurs applications électroniques. Néanmoins, le « scaling » des cellules Flash conventionnelles fait aujourd’hui face à plusieurs limitations et un effort d’optimisation accru est nécessaire pour atteindre de meilleures performances, notamment en terme de fiabilité (rétention de données et tenue en endurance). La rétention de l’information stockée a ainsi fait l’objet de nombreuses études dans la littérature, aboutissant à une bonne compréhension et une modélisation précise des phénomènes de Stress Induced Leakage Current (SILC). En revanche, une description précise et microscopique des mécanismes de dégradation de cellules Flash en cours d’endurance Programmation/Effacement (P/E) reste manquante. Notamment dans le cas des technologies Flash de type NOR, dont la nature 2D des mécanismes de dégradation complexifie l’analyse, la compréhension et la modélisation de la perte de performances en cours d’endurance.Cette thèse se propose d’investiguer le vieillissement en endurance de la technologie embarquée NOR Flash 40nm produite à STMicroelectronics. Grâce à un ensemble de caractérisations électriques et de simulations TCAD spécifiquement développées, la thèse fourni une compréhension physique des différents mécanismes de vieillissement impliqués durant l’endurance. En particulier, les rôles respectifs des opérations de Programmation (par porteurs chauds) et d’Effacement (par injection Fowler-Nordheim) sont soulignés et leur impact sur les caractéristiques des cellules mémoires établis. Enfin, grâce à la description microscopique et exhaustive précédemment établie, un modèle physique reproduisant la dégradation de la cellule pendant l’endurance est proposé. L’application de ce modèle permet de définir des conditions de programmation optimales conduisant en une amélioration de la durée de vie des cellules NOR Flash considérées
Flash technology still represents the preferred storage memory in many portable consumers and computer applications. However, the conventional Flash cell is now facing technological barriers and needs to be optimized pushing its working condition to the intrinsic physical limit. Such an optimization has to be done mainly focusing on reliability concerns, i.e. data retention and endurance, since representing the main limiting factors of technology down-scaling. For this reason, several works dealt with data retention concerns analyzing, characterizing and modeling the Stress Induced Leakage Current (SILC) with the final aim of limiting or control such an issue. However, there is no work which accurately explored the overall cell evolution during Program/Erase (P/E) cycling from a microscopic physical standpoint, especially in NOR technology, whose intrinsic 2D degradation nature makes complex the modeling and the analysis of the combined aging mechanisms.In this thesis, an in-depth investigation of P/E degradation mechanisms in 40nm NOR Flash technology issued from STMicroelectronics is conducted. With the help of advanced electrical characterization and proper TCAD simulation, this thesis provides an accurate understanding, evaluation and modeling of the different aging mechanisms involved during P/E cycling. In particular, the respective roles of Hot Carrier Degradation (HCD) and Fowler-Nordheim Stress (FNS) are pointed out, and their impact on memory cell characteristic drifts and on memory lifetime is assessed. The main challenge is to build a physically-based model which reproduces the Flash cell wear out during P/E cycling. This enables to push the memory lifetime towards its maximum intrinsic performance, as for example by correctly managing the P/E electrical operations. In addition, such an approach allows to assess the limiting physical mechanism factors for memory cell degradation and consequently to take action for some specific process step optimizations

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Sadkowska, A. M. "Arts-informed interpretative phenomenological analysis : understanding older men's experiences of ageing through the lens of fashion and clothing." Thesis, Nottingham Trent University, 2016. http://irep.ntu.ac.uk/id/eprint/29035/.

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The aim of this research was to investigate the possibility of adopting the lens of fashion and clothing in order to explore the older men’s experience of ageing. In this vein, as a creative practitioner, I sought to explore the vantage point and the relationship between fashion and clothing, embodiment and the physical and social processes of growing older in relation to individuals' experiences. A multi-disciplinary literature review revealed that fashion and clothing is a significant, yet often overlooked, element of individuals' experiences of ageing. Furthermore, this contextual review exposed an array of various influential stereotypes especially in regards to gender and ageing. Notably, the topic of older men and fashion seems to intersect two stereotypical assumptions; firstly, that fashion is a sphere exclusively reserved for women; and, secondly, that individuals' interest and engagement with fashion ceases significantly as they grow older. As a consequence, the majority of the existing studies investigating this phenomenon tend to focus on older women, their experiences and expectations towards clothing. While there is no doubt that such scholarship is valuable, such an imbalance needs to be addressed. Via this thesis I aim to contribute to the fulfillment of this identified gap in knowledge. In this research, I have developed a novel hybrid methodology, Arts-Informed Interpretative Phenomenological Analysis. Rooted in phenomenology and arts, this methodology put to the test the concept of 'making' as a valid way of data analysis, equal to writing. My research process built on the concept of the hermeneutic circle; the subsequent activities of writing and making allowed me to constantly move between different elements of the participants' experiences, which in turn facilitated the conditions for more in-depth and holistic understanding and enhanced interpretations. In addition, such an approach gave me the opportunity to utilise my skills and sensibilities as an artist and designer and to blur the boundaries between the artificially disconnected domains of fashion research and practice. This research found that ageing, fashion, clothing, men and masculinities are not disjointed. Fashion and clothing was not only revealed as a valid and useful lens through which individuals' experiences of ageing can be analysed and interpreted but also the experiences of men in this study proved to be rich and meaningful. This research culminated in a unified body of work that has relevance to the fields of psychology, sociology, as well as art and design. A composition of the research outcomes consisted of a series of suit jackets, short films and written accounts offering novel insights into a particular sample of men's individual and shared experiences of ageing. In addition, such a multi-layered composition of research outcomes has the potential to reach audiences beyond academia. Contributions to knowledge are claimed in the three following areas: . The novelty of the topic of investigation into mature men's experiences of ageing through the lens of fashion and clothing; . The uniqueness of the developed hybrid methodology, Arts-Informed Interpretative Phenomenological Analysis; . The originality of the outcomes arising from this investigation.

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Scheuplein, Anna-Lena [Verfasser], and Axel [Akademischer Betreuer] Mecklinger. "The aging episodic memory and factors which influence it : an electrophysiological investigation / Anna-Lena Scheuplein ; Betreuer: Axel Mecklinger." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2015. http://d-nb.info/1152094165/34.

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Robineau, Isabelle. "Les aidants familiaux : de leur reconnaissance à la fraternité." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC0037/document.

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Plus de quatre millions de personnes en France accompagnent un proche âgé dans la vie quotidienne. La moitié d’entre elles sont les enfants qui aident leur parent dit « dépendant » en raison d’un problème de santé. Longtemps confinés dans l’enceinte domestique, les aidants familiaux font l’objet depuis une vingtaine d’années d’une prise de conscience par notre société. En effet, leur investissement quotidien, s’il permet de maintenir à domicile leur aîné, peut toutefois porter atteinte à leur propre vie sociale et à leur propre santé. Les aidants familiaux ont besoin d’être soutenus eux-mêmes et ne se sentent pas suffisamment reconnus.Cette thèse a pour objet d’appréhender le monde des aidants familiaux et de la personne âgée dite dépendante à partir de la dimension morale des normes sociales de reconnaissance mises en évidence par Axel Honneth. Les problématiques des aidants ont été identifiées à partir de trois sphères de reconnaissance que sont l’amour, le droit et la solidarité. Celles-ci ont été considérées comme autant de sources d’injustices.Toutefois, « Aider autrui » peut apporter un lot de gratifications morales, en dépit d’une relation asymétrique engageant celui qui aide. L’implication des aidants familiaux auprès de leurs aînés donne corps à la solidarité de proximité basée sur le don. Bien qu’ils n’en soient pas toujours conscients, les aidants participent au bien commun, en dépit d’une doxa familialiste injonctive présente dans les politiques de la vieillesse de notre pays.La thèse se centre sur l’engagement des aidants pour contredire la vision individualiste et marchande sur laquelle repose la société libérale. L’exemple des aidants permet de penser le lien social sur d’autres critères que la compétitivité et la performance. Ainsi la solidarité de proximité qu’ils incarnent auprès de leurs parents vulnérables s’inscrit dans les valeurs véhiculées par le mouvement du care. Elle permet de réinvestir notre devise républicaine à travers la fraternité et de placer au cœur du débat politique un nouvel esprit du soin de l’autre et du soin de la collectivité dans notre démocratie
More than four million people in France care for a close family member in their daily life. Half of them are children helping their “dependent” relatives due to health problems.Confined to the home for long periods, caregivers have been taken into account by societal choices for the last twenty years. Indeed, their daily investment provides invaluable home-based care, but it can sometimes takes its toll on the caregiver as the family investment can affect their own state of health and social life. Caregivers themselves need support and often feel insufficiently recognized.This thesis focuses on discovering the world of carers for family members and for the elderly known as dependents, starting from the moral aspect of social standards of recognition highlighted by Axel Honneth.Caregivers’ issues have been identified on the basis of the three spheres of recognition that are love, legal relationships and social relationships. They have been considered as many sources of injustice.However, “helping others” can bring its share of moral rewards, despite the unbalanced relationship imposed on the helper. Caregivers’ involvement with their elders are often a source family solidarity based on giving. Not always consciously, caregivers can contribute to a common good, despite an injunctive “familialistic doxa” of the current old-age policies in our country. The thesis emphasizes the helpers’ commitment with the aim of refuting the individualistic and mercantile vision of the free market society. The example of helpers allows us to consider the social bond by other criteria than competitiveness and performance. The local solidarity that the givers embody next to their vulnerable parents are in line with values conveyed by the care movement.It enables us to reinvest in the motto of fraternity, a foundation of the French Republic, and examines a new spirit of caregiving to others and to community, one that is at the heart of our Democracy’s political questions

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Najjar, Raymond. "Non visual photoreception in humans : circadian consequences of spectral modulations of light." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10110.

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Chez les mammifères dont l’Homme, les rythmes circadiens physiologiques et comportementaux sont régulés par l’horloge centrale, localisée dans les noyaux suprachiasmatiques de l’hypothalamus. Possédant une période endogène proche mais pas exactement de 24 heures, cette horloge est constamment synchronisée à la période terrestre par le cycle lumière-obscurité perçu au niveau de l’oeil. Cette synchronisation entraîne l’expression de rythmes appropriés (hormonaux, veille-sommeil, température corporelle, etc.). Les hypothèses de ma thèse sont : 1- une exposition chronique à un spectre lumineux appauvri en longueurs d’ondes courtes, causée par l’opacification du cristallin chez le sujet âgé ou par l’exposition chronique à des lumières artificielles blanches, est à l’origine d’une altération de la réponse du système circadien à la lumière ; 2- une exposition chronique à un spectre lumineux enrichi en longueurs d’ondes courtes chez le sujet jeune, améliore la synchronisation du système circadien, la vigilance, les performances cognitives et la qualité du sommeil. L’objectif de ma thèse est d‘évaluer ces hypothèses selon deux approches : 1. Une approche physiologique : chez le sujet âgé sain, le brunissement physiologique du cristallin oculaire conduit à une filtration des longueurs d’ondes courtes du spectre lumineux. Cette approche inclus la mise au point et la validation d’un système de mesure de transmittance du cristallin in vivo. Ce système est nécessaire pour quantifier la qualité spectrale de la lumière atteignant la rétine. 2. Une approche artificielle : chez des sujets jeunes exposés de manière chronique (63 jours) à des lumières ambiantes blanches ou enrichies en longueurs d’ondes courtes
Physiological and behavioral circadian rhythms in mammals and humans are under the control of a central clock located in the suprachiasmatic nuclei of the hypothalamus. This endogenous clock has a period close to but not exactly 24 hours and therefore needs to be constantly entrained to the 24-h period of the earth, by the light-dark cycle. Light is perceived through the eyes and implicates all the retina’s photoreceptors (rods, cones, melanopsin ganglion cells (ipRGCs)). A properly entrained circadian system leads to an appropriate rhythmic expression of many physiological functions (hormonal secretion, sleep/wake cycles, core body temperature …). My project’s hypotheses are: 1- a chronic exposure to blue deprived light, as occurring in the aged due to lens filtration or under standard indoor lighting, leads to a decreased nonvisual sensitivity to light.; 2- exposure to blue enriched white light in the young subjects enhances non-visual responses to light such as, entrainment of the circadian system, vigilance, mood, sleep quality and cognitive performance. The aim of my thesis is to evaluate these hypotheses using two approaches : 1. A physiological approach: In the aged subject, in whom the ocular crystalline lens specifically filters short wavelength lights, known to be crucial for circadian entrainment. This approach includes the development and clinical validation of a scotopic heterochromatic flicker photometry technique to assess lens transmittance in vivo. This technique is essential to evaluate individual light spectra reaching the retina. 2. An artificial approach: In young subjects chronically exposed (63 days in the Concordia base, Antarctica) solely to standard white or blue enriched white light

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Carvalho, Cyril. "Modulation de la sénescence induite par les oncogènes par les glucocorticoïdes et rôle de EGR1." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS183/document.

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La sénescence cellulaire est un mécanisme suppresseur de tumeur. En effet, elle se caractérise par l’inhibition irréversible de la prolifération cellulaire, en réponse par exemple à l’expression de certains oncogènes activés. In vivo, les névi, dont 80% expriment l’oncogène B-RAF-V600E, sont des exemples visibles d’un tissu composé de cellules exprimant un oncogène et sénescentes, protégeant ainsi de la transformation vers le mélanome. On retrouve cependant B-RAF-V600E dans 50% des mélanomes malin, ce qui implique la possibilité d’un échappement à la sénescence. Lors de ma thèse, j’ai étudié les mécanismes d’induction de sénescence par B-RAF-V600E, et un possible mécanisme d’échappement induit par les glucocorticoïdes (GC). Les GC sont fréquemment utilisés en traitement topique pour leurs propritétés anti-inflammatoire mais aussi comme immunosuppresseurs. Nous avons constaté qu’ils interfèrent avec l’induction de la sénescence in vitro. En étudiant leurs effets sur les modifications du programme transcriptionnel induites par l’expression de B-RAF-V600E, j’ai mis en évidence le rôle d’une de leurs cibles, le facteur de transcription EGR1, dans l’induction de la senescence. Les GC réduisent l’expression de EGR1 et EGR1 contrôle positivement l’expression des inhibiteurs de kinases dépendantes de cycline CDKN2B et CDKN1A. EGR1 se comporte comme un senseur du niveau d’activation de la voie MAPK/ERK pour induire un arrêt rapide de la prolifération. J’ai aussi constaté que les GC, mais pas la perte de EGR1, permettent un échappement total à la sénescence induite par B-RAF-V600E, impliquant l’existence d’autres cibles. Mes résultats montrent le rôle de EGR1 dans l’induction de la sénescence et incitent à évaluer l’effet des glucocorticoïdes sur la tumorigénèse liée à l’expression de B-RAF-V600E et dans l’augmentation de la prévalence des cancers de la peau chez les patients greffés
Cellular senescence is a tumor suppressor mechanism. Indeed, it corresponds to an irreversible cell cycle arrest, in response for instance to the expression of an activated oncogene. In vivo, nevi, 80% of which express the B-RAF-V600E oncogene, are composed of cells that expressed an oncogene and became senescent, protecting against progression to melanoma. Nevertheless, B-RAF-V600E is found in 50% of malignant melanoma, which implies mechanisms of senescence escape. During my PhD, I studied the mechanisms of senescence induction by B-RAF-V600E, and a possible escape mechanism by glucocorticoids (GC). GC are often used in topical treatment of skin diseases for their anti-inflammatory properties, and are also used as immunosuppressant. We observed that they interfere with senescence induction in vitro. While studying the effects of GC, I identifiedone of their targets, transcription factor EGR1, and showed that GC repress EGR1 which positively controls the expression of cell cycle inhibitors CDKN2B and CDKN1A. EGR1 acts as a sensor of the level of MAPK/ERK pathway activation to induce a rapid cell-cycle arrest. I also showed that GC, but not the loss of EGR1, allow full escape to senescence induced by BRAF-V600E, implying the existence of other targets. My results demonstrate the role of EGR1 in senescence induction, and highlight the need to evaluate GC action on tumorigenesis linked to B-RAF-V600E, as well as in the higher prevalence of skin cancers in transplanted patients

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Emile, Mélanie. "Les stéréotypes liés au vieillissement : antécédents, conséquences et modérateurs dans le domaine de l’activité physique." Thesis, Nice, 2014. http://www.theses.fr/2014NICE4105/document.

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Les seniors ne sont pas suffisamment active au regard des recommandations actuelles. Cette inactivité physique serait due en partie à des barrières psychologiques ; les stéréotypes liés au vieillissement. L’objectif de cette thèse est d’identifier le rôle de ces stéréotypes, et leurs conséquences sur l’activité physique. La première étude est la continuité de l’élaboration et de la validation d’un outil psychométrique mesurant les stéréotypes liés à la pratique de l’activité physique des seniors. La deuxième étude révèle que l’ouverture aux expériences et les théories implicites de l’habileté sont des corrélats personnels de l’internalisation des stéréotypes liés au vieillissement, et sont reliés au niveau d’activité physique des seniors. La troisième étude montre que l’adhésion aux stéréotypes liés au vieillissement dans le domaine de l’activité physique prédit la santé par l’ego déplétion en diminuant la vitalité de seniors actifs. La quatrième étude suggère que les théories incrémentielles sont plus efficaces sur une tâche de force lorsqu’elles sont associées à des informations contre-stéréotypées. La dernière étude révèle que les seniors bénéficiant d’un programme de marche et d’une intervention psychosociale, ont obtenu des scores plus élevés de stéréotypes bénéfices de l’activité physique, de perceptions de la valeur physique et de la compétence sportive, d’apparence physique, de qualité de vie et d'endurance physique, et des scores plus faibles de stéréotypes risques de l’activité physique. Ces résultats indiquent que ces stéréotypes ont évolué positivement chez des femmes seniors sédentaires, apportant ainsi un appui à une conception malléable des stéréotypes
Older adults are not sufficiently active against the current recommendations. The approach adapted in this thesis was that physical inactivity was partly due to psychological barriers, notably aging stereotypes. The main objective of this thesis was to identify the role of aging stereotypes, and their relation with physical activity. We defend the thesis that aging stereotypes affect older adults’ health-behaviors. In the first study, we contribute to the validation of a psychometric tool which measuring aging stereotypes in the physical activity domain. The second study reveals that openness to experience and implicit theories of ability are personal correlates of internalization of aging stereotypes, and are linked to the level of physical activity in older adults. The third study shows that endorsement of aging stereotypes in physical activity domain predicted health though ego depletion, including lowering the subjective vitality in active older adults. The fourth study suggests that incremental theories of ability are more effective on a task related to the physical capacities when counter-stereotypical information is given. The last study of this thesis shows that older adults who participated on exercise program combined with psychosocial intervention report higher scores of stereotypes related to benefits of the physical activity, physical self-perceptions, quality of life and physical endurance, and lower scores of stereotypes relative to risks of physical activity

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Machat-From, Laura. "Identity, Old(er) Age and Migrancy : A Social Constructionist Lens." Doctoral thesis, Linköpings universitet, Avdelningen Åldrande och social förändring, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-137460.

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ldentity research in relation to ethnicity and migration has tended to focus an younger people whilst identity research in relation to ageing and old(er) age has not focused an migrants. This inadvertent mutual neglect has led to a lack of identity research that examines the identity categories of old(er) age and migrancy together, a lacuna that this dissertation aims to redress. This dissertation departs from a social constructionist understanding of identity as situationally accomplished in the interplay between how one defines oneself (internally) and how others define one (externally). The questions raised by this perspective and addressed in this dissertation are: When (in what situations) and in relation to whom do old(er) age and migrancy (respectively) seem to become meaningful for identification? How do the identity categories of old(er) age and migrancy seem to be negotiated? The empirical material consists of in-depth interviews with 24 older migrants (13 men, 11 women) aged between 55 and 79 who have been living in Sweden for 18 to 61 years. Interviewees come from 12 different countries that vary in perceived cultural distance from Sweden. The findings suggest that identifications with old(er) age and migrancy seem to be dynamic and flexible rather than necessarily permanently meaningful, thus gaining meaning in specific situations and in relation to particular Others. External definitions furthermore do not always seem to match with internal ones. Regardless of how old(er) age and migrancy are constructed, they seem to be negotiable. This dissertation thus contributes to identity research by studying old(er) age and migrancy together and furthermore sheds light onto how the social constructionist lens allows us to see variability where stability otherwise would be presumed.
ldentitetsforskning rörande etnicitet och migration har huvudsakligen fokuserat på yngre medan identitetsforskning kring äldre och åldrande inte har fokuserat på utrikesfödda. Som en konsekvens därav har identitetsforskningen inte studerat hög(re) ålder och invandrarskap tillsammans, en lucka som denna avhandling avser att fylla. Avhandlingen utgår ifrån en socialkonstruktionistisk förståelse av identitet som situationsbunden och formad genom samspelet mellan hur man definierar sig själv (internt) och hur andra definierar en (externt). Frågorna som väcks genom detta perspektiv och som avhandlingen fokuserar på är: När (i vilka situationer) och i förhållande till vem verkar hög(re) ålder respektive invandrarskap bli betydelsefulla för identifikationer? Hur verkar identitetskategorierna hög(re) ålder och invandrarskap förhandlas? Det empiriska materialet består av djupintervjuer med 24 utrikesfödda äldre (13 män, 11 kvinnor) i åldrarna mellan 55 och 79 som har bott i Sverige mellan 18 och 61 år. lntervjupersonerna kommer från 12 olika länder med olika upplevt kulturellt avstånd från Sverige. Resultaten tyder på att identifikationer med hög(re) ålder och invandrarskap är dynamiska och flexibla snarare än nödvändigtvis permanent meningsfulla, och får därmed betydelse i vissa situationer och i förhållande till särskilda andra. Externa definitioner verkar inte alltid stämma överens med interna definitioner. Oavsett hur hög(re) ålder och invandrarskap är konstruerade så framstår de som förhandlingsbara. Avhandlingen bidrar därmed till identitetsforskningen genom att studera hög(re) ålder och invandrarskap tillsammans och belyser dessutom hur det socialkonstruktionistiska perspektivet tillåter oss att se variation och föränderlighet där stabilitet annars förutsätts.

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Rousselin, Thomas. "Modélisation et interprétation des effets combinés vieillissement/SEE dans les technologies d'échelles nanométriques appliquées au domaine avionique." Thesis, Toulouse, ISAE, 2018. http://www.theses.fr/2018ESAE0044/document.

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L’électronique embarquée dans l’aéronautique, couramment appelé avionique, est chargée d’effectuer des tâches critiques et doit présenter une fiabilité élevée. La technologie Complementary Metal Oxyde Semiconductor (CMOS) est couramment utilisée pour réaliser des composants critiques, comme des mémoires. Les composants CMOS sont susceptibles à deux types d’erreurs : les dégradations liées au vieillissement et les évènements singuliers causés par les particules cosmiques. Or, les conditions d’utilisation de l’avionique renforcent la fréquence d’occurrence de ces deux types d’erreurs. Le vieillissement consiste, pour les composants CMOS, en la dégradation de ses interfaces métal/oxyde et oxyde/semi-conducteur au cours de sa durée de vie. Les composants avioniques subissent un vieillissement accéléré de par leur condition d’utilisation intensive. Le rayonnement cosmique est composé de particules énergétiques d’origine extrasolaire. Certaines de ces particules sont susceptibles d’interagir un composant électronique et d’y déposer de l’énergie, cela peut causer une erreur appelée évènement singulier. L’avionique est particulièrement concernée par cette problématique car ces évènements peuvent être critiques et qu’elle rencontre un flux élevé de particules.Auparavant, la sensibilité aux radiations était considérée comme indépendante du vieillissement. Seulement, les évolutions des technologies CMOS nous amènent à remettre en cause cette hypothèse. Afin d’étudier ce nouveau phénomène, une méthode de modélisation a été développée. Celle-ci couple la modélisation des évènements singuliers à une modélisation électrique circuit du vieillissement. Elle permet d’effectuer des simulations sur un circuit mémoire spécifique dans des environnements radiatifs variés. De ces simulations ressortent l’influence de certains paramètres électriques, qui permettent de proposer une simulation opérationnelle appliquée à l’avionique
CMOS technologies used in avionics are prone to both aging and soft error caused by cosmic rays. The ongoing technology scaling has improved the radiation sensitivity of memory cells while the contribution of degradations mechanisms remained unchanged. Considering this trend, the hypothesis that radiation sensitivity does not change over the lifetime of a component must be challenged. In order to do so, a modelling methodology is proposed. It is based on an existing radiation modelling device and includes an electrical aging modelling. This modelling is used to characterize the aging impact on radiation sensitivity of several memory cells under different radiative environment. The impact of diverse electrical parameters is noted and an operative avionics study is finally proposed

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Peressini, Lopez Paula. "Activité du rétrotransposon L1 dans les cellules musculaires." Electronic Thesis or Diss., Université Côte d'Azur, 2020. http://theses.univ-cotedazur.fr/2020COAZ6007.

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Près de la moitié du génome humain provient d'éléments transposables (TE). Parmi eux, l'élément LINE-1 ou L1 (Long INterspersed Element-1) forme la seule famille d'éléments transposables actuellement active et autonome chez l'Homme. Bien que des centaines de milliers de copies soient dispersées dans le génome humain, seules 80 à 100 d'entre elles sont encore compétentes pour la rétrotransposition, c'est-à-dire capables de se reproduire par un mécanisme de "copier-coller" via un ARN intermédiaire et une étape de transcription inverse. L'activité des L1s peut avoir des conséquences délétères, en particulier par mutagenèse insertionnelle. Elle est néanmoins étroitement régulée au niveau transcriptionnel et post-transcriptionnel. Inversement, des facteurs d'hôtes spécifiques sont nécessaires pour accomplir le cycle réplicatif des L1s. Lorsqu'elles se produisent dans la lignée germinale ou dans l'embryon précoce, les insertions de L1 peuvent être transmises à la génération suivante. La rétrotransposition des L1s a également été décrite dans certains tissus somatiques, comme dans les tumeurs épithéliales et dans le cerveau, à la fois dans les cellules progénitrices neurales et dans les neurones différenciés. Néanmoins, les niveaux d’expression des L1 compétents pour la rétrotransposition, et leur mobilisation, dans d'autres tissus somatiques restent incertains.Ici, nous avons étudié l'activité des rétrotransposons L1 dans les cellules musculaires squelettiques humaines et murines. Nous montrons que la protéine du L1 la plus abondante, ORF1p, qui est essentielle à la rétrotransposition, est indétectable dans nos conditions expérimentales, dans des échantillons murins ou humains de muscle squelettique, alors qu'elle est facilement détectable dans les cellules cancéreuses ou dans les testicules. De même, elle n'est pas détectée dans les myoblastes immortalisés d’origine murine ou humaine. En revanche, nous avons découvert que le L1 est capable de rétrotransposition dans les myoblastes humains et murins lorsqu'elle est exprimée à partir d'un plasmide ou d'une copie intégrée avec un promoteur constitutif ou inductible, respectivement. En conclusion, si l'expression du L1 est inférieure à la limite de détection dans le muscle, les myoblastes sont bien permissifs à la rétrotransposition, ce qui indique que ces cellules expriment tous les facteurs cellulaires nécessaires pour réaliser ce processus, et n'expriment pas de facteurs de restriction significatifs qui bloqueraient la rétrotransposition.Dans l'ensemble, nos résultats suggèrent que l'activité somatique des L1s pourrait ne pas être restreinte au cerveau ou aux cellules cancéreuses, mais pourrait également avoir lieu dans les muscles dans des conditions environnementales ou pathologiques qui déclencheraient leur expression
Almost half of the human genome derives from transposable elements (TE). Among them, the Long INterspersed Element-1 (LINE-1 or L1) forms the only currently active and autonomous transposable element family in humans. Although hundreds of thousands L1 copies are dispersed in the human genome, only 80-100 of them are still retrotransposition competent, i.e. able to replicate by a “copy-and-paste” mechanism via an RNA intermediate and a reverse transcription step. On the one hand, L1 activity can have deleterious consequences, such as insertional mutagenesis, and is tightly regulated at the transcriptional or post-transcriptional levels. However, specific host factors are necessary for completion of L1 replication cycle. When occurring in the germline or in the early embryo, L1 insertions can be transmitted to the next generation. Somatic retrotransposition has been also described in epithelial tumors and in the brain, both in neural progenitor cells and differentiated neurons. Nevertheless, the extent of L1 expression and mobilization in other somatic tissues remains unclear.Here, we investigated the activity of L1 retrotransposons in human and mouse skeletal muscle cells. We show that the most abundant L1 protein, ORF1p, which is essential to retrotransposition, is undetectable under our experimental conditions, in mouse or human muscle samples, while it is readily detected in cancer cells or in testis. Similarly, it was undetected in immortalized mouse or human myoblasts. However, we found that L1 is capable of retrotransposition in human and mouse myoblasts when expressed from a plasmid or from an integrated copy with a constitutive or inducible promoter, respectively. In conclusion, while L1 expression is under the limit of detection in muscle, myoblasts are permissive to retrotransposition, indicating that these cells express all the cellular factors necessary to achieve this process, and do not express significant restriction factors that would prevent retrotransposition.Altogether, our findings suggest that somatic L1 activity could not be confined to the brain or cancer cells, but could also occur in muscles under environmental or pathological conditions that would unleash L1 expression

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Ha-Ahn, Tung. "Influence du vieillissement thermo-oxydatif sur les comportements mécaniques du polychloroprène Influence of thermo-oxidative aging on the mechanical behaviors of polychloroprene /." [S.l. : s.n.], 2007.

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Prashant, Arvind pala. "Approche ecologique de l’’evaluation de la memoire episodique dans le vieillissement normal et les neuropathologies." Thesis, Bordeaux 2, 2013. http://www.theses.fr/2013BOR22121/document.

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A ce jour, nous savons peu de choses sur la manière dont la mémoire épisodique quotidienne, visuellement riche et complexe en termes d’éléments contextuels, est affectée par le vieillissement normal contrairement aux connaissances acquises dans le domaine du vieillissement sur la mémoire épisodique verbale ou visuelle au moyens des tests traditionnels ou des procédures de laboratoire comme le paradigme de rappel libres multi-essais (e.g., utilisé par le California Verbal Learning Test). La présente thèse s’est par conséquent attachée à implémenter ce paradigme traditionnel de rappels libres multi-essais d’évaluation de la mémoire épisodique au sein d’un dispositif RV simulant une visite dans un appartement, le HOMES test (Human Objet Memory of Everyday Scenes test). Cette procédure permet de dériver des indices d’apprentissage, de catégorisation, d’interférence proactive, de bénéfice de la reconnaissance comparée au rappel libre, et de fausses reconnaissances. A cela, nous nous sommes intéressés aux relations entre la mémoire quotidienne et l’action à travers l’effet denavigation active.A l’aide d’études comparatives, nous avons retrouvé le profil mnésique classiquement observé avec le test « papier-crayon », excepté pour l’interférence proactive qui n’est pas observée comme augmentée chez les participants âgés. En effet, des scores de rappel réduits,un bénéfice accru de la reconnaissance, une sensibilité augmentée aux fausses reconnaissances, et des capacités de regroupements sémantiques sont obtenus. Chez les jeunes adultes avec traumatisme crânien (étude 1), un profil identique est observé alors qu’un profil bien différent est obtenu auprès des patients avec maladie Alzheimer (étude 2) avec notamment un tableau associant des déficits plus marqués et des capacités de catégorisation altérées. Les études 3 et 4 adressant l’effet de navigation active chez le sujet jeune et âgé, ont mis en évidence un effet bénéfique de la navigation active sur la reconnaissance chez les deux groupes de sujets. Par contre, la navigation active diminuait les fausses reconnaissances des jeunes mais augmentait celles des âgés. Nous discutons les résultats de ces études sur la mémoire quotidienne à travers les hypothèses de déficit-item spécifique et du déclin fronto-exécutif du vieillissement normal
To this day, very little is known about the way aging affects everyday episodic memory, which is a visually and contextually rich and complex memory. However, episodic memory is traditionally assessed using verbal tasks which are lacking such complexity. One of them, the California Verbal Learning Test (CVLT) uses the multi-trial free recall paradigm that we also implemented in the Human Object Memory of Everyday Scenes test using virtual reality to simulate a visit in an apartment (the HOMES test).This procedure allowed us to assess multiple memory processes such as learning, semantic clustering, proactive interference, recall versus recognition, and false recognitions. We also wanted to investigate the relationship between everyday memory and action through active navigation and its effects on each of these processes. We showed the typical profile of older adults usually obsereved using traditional paper-pencil tests on most of the memory indices except for proactive interference, which was not increased. In fact, older adults showed a reduced free recall performance despite a preserved learning ability across trials, a benefit from recognition but also a higher susceptibility to false recognitions. TBI patients (study 1) showed a profile similar to that of older adults, but patients with Alzheimer disease were impaired on all of the HOMES indices (study 2). Studies 3 and 4 examined the beneficial effect of active navigation in younger and older adults’ everyday memory and showed that that recognition was the measure that benefited the most in both age groups. In contrast, older adults while active navigation decreased false recognitions in younger adults, it actually increased false recognitions in older adults. Our results on everyday memory are discussed in terms of item-specific deficit and executive deficit hypotheses in normal aging

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Alles, Benjamin. "Profils de comportement alimentaire et déclin cognitif chez les personnes âgées en Aquitaine et au Québec." Thesis, Bordeaux 2, 2013. http://www.theses.fr/2013BOR22054/document.

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Les profils de comportement alimentaire ou de consommation de nutriments sont des stratégies prometteuses pour étudier le lien entre nutrition et fonctions cognitives chez les personnes âgées, car ils permettent de prendre en compte la complexité des apports alimentaires. Des profils dits « sains », définis a priori pour évaluer l’adhérence à une alimentation spécifique, ou construits a posteriori à partir des données observées, ont été associés à de meilleures fonctions cognitives. Jusqu’à présent, aucune étude n’avait estimé l’association longitudinale entre profils a posteriori et déclin cognitif. L’objectif principal de cette thèse en cotutelle entre l’Université Bordeaux Segalen et l’Université Laval était d’investiguer l’association entre des profils de nutriments a posteriori et le déclin cognitif par une analyse longitudinale dans deux cohortes de personnes âgées en France et au Canada. Parmi les participants français de l’étude Trois-Cités (3C) et ceux de l’étude longitudinale québécoise NuAge, respectivement 1388 et 1454 sujets avaient des mesures répétées de cognition et des données nutritionnelles à l’inclusion. Une méthode similaire d’analyse en composantes principales a été utilisée, permettant d’identifier trois profils de nutriments dans chaque cohorte. La qualité de l’alimentation et les caractéristiques du mode de vie et socioéconomiques associées à chaque profil de nutriments ont été décrites dans une première étude. Ensuite, des analyses longitudinales ont été menées pour estimer l’association entre la fonction cognitive, son déclin et les profils de nutriments identifiés. Dans les deux cohortes, un premier profil a été observé associé à une meilleure qualité nutritionnelle en opposition à un second profil de moins bonne qualité nutritionnelle. Dans l’étude 3C, le profil « sain » était associé à de meilleures fonctions cognitives à l’inclusion alors que le profil « occidental » était associé à de moins bonnes fonctions cognitives. Aucune association entre profils de nutriments et déclin cognitif dans le temps n’a été observée dans les deux cohortes. Le niveau de preuve concernant des profils de consommation d’aliments ou de nutriments chez l’aîné n’est pas suffisant pour le développement de politiques publiques nutritionnelles de prévention du déclin cognitif
Dietary or nutrient patterns may be promising strategies to investigate the association between nutrition and cognitive function in older persons, because they capture the complexity of food intake. Both a priori defined, measuring adherence to specific diets, and a posteriori data driven dietary patterns have been reported to be associated with better cognitive function in older persons. To date, no study has investigated the link between a posteriori derived nutrient patterns and cognitive decline. The main objective of this thesis, co-directed between University Bordeaux Segalen and University Laval, was to assess the relationship of nutrient patterns with cognitive impairment and decline in two cohorts of older persons from France and Canada in a longitudinal analysis. Among the subjects from the Three-City (3C, France) study and Quebec Longitudinal Study NuAge (Quebec, Canada), respectively 1,388 and 1,454 had nutritional data at baseline and repeated measures of global cognitive function over 5 years. A similar principal component analysis was used in the two samples to derive nutrient patterns and allow the identification of three nutrient patterns in each study. The diet quality, lifestyle and socio-economic characteristics associated with each nutrient pattern were described in a first study. Then, longitudinal analyses were performed in both cohorts to estimate the association between nutrient patterns and cognitive function or decline. In both cohorts, we observed an opposition in diet quality between the first two nutrient patterns. In 3C, the healthy nutrient pattern was associated with better cognitive function at baseline, whereas the western nutrient pattern was associated with cognitive impairment at baseline. No association between any of the nutrient patterns and cognitive decline was reported in both cohorts. To date, the evidence concerning dietary or nutrient patterns and cognitive function in older persons does not yet allow the development of nutritional policies and programs to prevent cognitive decline

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Dufour, Elsa. "Relation entre la microstructure de fibres creuses PVdF, les propriétés physico-chimiques et les performances de filtration." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2015. http://www.theses.fr/2015ENCM0001.

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Le projet NEOPHIL a pour ambition d'élaborer une membrane d'ultrafiltration (UF) en fibre creuse de poly(fluorure de vinylidène) (PVdF) possédant une résistance au colmatage stable dans le temps. Cette propriété peut être acquise par l'ajout d'un copolymère à blocs nommé GEN dans la solution de préparation des fibres en plus de l'additif poly(vinyl pyrrolidone) (PVP) classiquement utilisé. Dans ce travail, nous nous sommes attachés à la détermination des additifs en surface, dans la masse et à établir des profils de concentration par ATR-FTIR, T%-FTIR et microscopie Raman. Ces analyses ont montré que la moitié de la PVP est lessivée dans le bain de coagulation alors que GEN reste quantitativement ancré dans la matrice. Dans le cas de la PVP, les paramètres d'élaboration comme la présence de solvant ou de PVP dans le bain de coagulation influent fortement sur le profil de concentration au niveau des interfaces. Par la suite, une analyse multicritère entre l'hydrophilie apportée par les additifs et le colmatage a été effectuée. Cette étude a été réalisée par des mesures d'angle de contact à l'eau, de rétention d'eau et de pression d'intrusion d'eau sur fibres sèches en relation avec la taille et la distribution des pores, la rugosité de surface (AFM) et la perméabilité à l'eau pure. La rétention d'eau et la pression d'intrusion d'eau semblent les deux techniques les plus pertinentes pouvant relier les propriétés physico-chimiques et les performances de filtration. Une étude préliminaire sur le comportement au vieillissement a également été effectuée qui montre que GEN est peu extrait alors que la PVP disparait en partie par extraction et/ou dégradation. Ce phénomène affecte fortement les différents paramètres étudiés dans l'analyse multicritère
The project NEOPHIL aims to develop an ultrafiltration (UF) membrane hollow fiber from poly (vinylidene fluoride) (PVdF) that resists to fouling amide time. This property can be achieved by adding a block copolymer called GEN in the fiber preparation solution in addition to the classic additive, poly (vinyl pyrrolidone) (PVP). In this work, we focused on the quantification of additives on the surface, in the bulk and establishing the concentration profile by ATR-FTIR, T% -FTIR and Raman microscopy. These analyzes showed that half of the PVP is washed away into the coagulation bath while GEN quantitatively remains anchored in the matrix. In the case of PVP, the formulation parameters such as the presence of solvent or PVP in the coagulation bath greatly affects the concentration profile at the interfaces. In addition a multi-criteria analysis between hydrophilicity provided by the additives and the fouling was established. This study was carried out by measurement of the water contact angle, water retention and water intrusion pressure of dry fibers in relation to the size and distribution of pores, the surface roughness (AFM) and the permeability to pure water. Water retention and water intrusion pressure seem to be the two most relevant techniques that can connect the physicochemical properties and filtration performance. A preliminary study on the aging behavior was also performed showing that GEN is not extracted while the PVP is lost partly by extraction and/or degradation. This phenomenon strongly affects the different parameters studied in the multi-criteria analysis

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Zebian, Abir. "Etude du facteur de réparation de l’ADN, Xeroderma pigmentosum du groupe C (XPC), dans les cellules souches hématopoïétiques." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0223/document.

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Les dommages de l'ADN peuvent s’accumuler dans les cellules souches hématopoïétiques(CSH) suite aux stress externes ou métaboliques et perturber leur fonctionnement et/ou leur maintien.La réparation par excision de nucléotides (NER), initiée par l’arrêt de la transcription (TCR) ou par lareconnaissance de distorsions des régions non transcrites (GGR) de l’ADN, est nécessaire àl’hématopoïèse à long terme. XPC, un facteur clé du système GGR, participe à d’autres réponses austress oxydatif. Le laboratoire a montré que la perte de XPC provoque l’accumulation de mutations, unstress métabolique et la carcinogenèse. Notre objectif est d’évaluer son expression et son rôle dans lemaintien et la différenciation des CSH. Nos résultats montrent qu’il est plus exprimé dans les cellulesimmatures CD34+ que dans les CD34- matures. Aussi, XPC apparaît sous trois poids moléculairesdifférents certainement liés à des modifications post-traductionnelles. Son extinction par ARNinterférence n'affecte ni la prolifération ni la capacité progénitrice in vitro des cellules CD34+.Cependant, les cellules déficientes implantées chez des souris immunodéficientes disparaissentprogressivement suggérant une perte des CSH ou de leur capacité de différenciation. Postulant queles mutations s’accumulent avec le temps, nous avons étudié l’hématopoïèse chez des sourisdéficientes en XPC jeunes et âgées. Les différences décrites dans l’hématopoïèse chez les individusjeunes et âgés sont retrouvées mais, de manière surprenante, aucune différence entre les animauxsauvages et mutés quelque soit l’âge ou le stress génotoxique n’est observée. Les résultats obtenussur les cellules humaines démontrent un rôle potentiel de XPC dans l’hématopoïèse, mais denouvelles investigations sont nécessaires pour mieux comprendre les mécanismes impliqués, et lapossible participation de XPC dans la leucémogenèse
DNA damage may accumulate in hematopoietic stem cells (HSC) due to external ormetabolic stresses, leading to perturbation in their function and/or maintenance. Nucleotide excisionrepair (NER), initiated in the DNA by the stop of transcription (TCR) or by the recognition of distortionsin transcribed regions (GGR), is necessary for long-term hematopoiesis. XPC, a key factor in GGR, isimplicated in oxidative stress. The laboratory has demonstrated that XPC loss leads to theaccumulation of mutations, metabolic stress and carcinogenesis. Our objective is to evaluate XPCexpression and its role in HSC maintenance and differentiation. Results showed that XPC is highlyexpressed in immature CD34+ cells compared to mature CD34- cells. In addition, XPC appeared withthree different molecular weights, certainly linked to post-translational modifications. XPC silencing byshRNA did not affect the proliferation or the progenitor ability of CD34+ cells in vitro. However, deficientcells transplanted in immunodeficient mice disappeared progressively, suggesting the loss of HSCs ortheir differentiation capacity. Postulating that mutations accumulate with time, we have studiedhematopoiesis in young and aged XPC deficient mice. Differences described in young and agedhematopoiesis systems were found but, surprisingly, no difference was observed between wild typeand mutant mice at any age or genotoxic stress. Data from human cells demonstrate a potential rolefor XPC in HSC but new investigations are necessary to better understand the mechanisms implicatedand if XPC may participate in leukemogenesis

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Tong, Xiaohui. "Rôle de la synthèse des miARN par le tissu adipeux dans les pathologies de vieillissement." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30332.

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Au cours du vieillissement, le tissu adipeux devient sénescent ce qui conduit à une altération des capacités fonctionnelles de l'adipocyte. En effet, la senescence est un arrêt du cycle cellulaire qui entraîne la perte de fonction et entretient un profil inflammatoire. Ces changements participent à l'installation progressive de pathologies associées au vieillissement comme le diabète, l'athérosclérose ou les maladies neurodégénératives. Afin de mieux comprendre le rôle des sécrétions de l'adipocyte dans la perte de fonction de cette cellule, nous avons analysé la production de micro ARNs de l'adipocyte âgé chez la souris. Depuis plusieurs années, l'étude des micros ARNs montre que ces molécules pourraient devenir des cibles thérapeutiques de premier plan ou des biomarqueurs spécifiques. Dans ce contexte, nous avons analysé et caractérisé le MiRnome de l'adipocyte chez la souris âgée et nous avons pu démontrer que le Mir-1949 pouvait jouer un rôle important dans la perte de fonction de l'adipocyte au cours du vieillissement. En effet, l'expression et la sécrétion adipocytaire de mir- 1949 sont augmentées avec l'âge et semblent être associées à l'état de senescence de la cellule adipeuse. De plus, l'augmentation de mir-1949 provoque une altération des fonctions de l'adipocyte in vitro. L'ensemble de ces résultats préliminaires montre que mir-1949 pourrait devenir une adipokine d'intérêt à cibler au cours du vieillissement
On the one part, dicer, the RNase III endoribonuclease responsible for microRNAs maturation, has been reported to be decreased in adipocytes during ageing. With the use of tamoxifen inducible dicerlox/lox/ adiponectin-CreERT2 mice, we found that adipocyte dicer deficiency promoted the onset of some of the age-related complications such as reduced adipocyte sizes and dysfunctions in systemic metabolism. The abrogation of white adipocyte markers such as Pparγ, Glut4 or Hsl, indicated that dicer is indispensible for the maintainance of white adipocyte identity. In addition, the results that there were lipid accumulation and fibrosis in liver in tamoxifen treated dicerlox/lox/ adiponectin-CreERT2+ mice, indicated that adipocyte dicer deficiency might contribute to liver aging. Mechanistically, mitochondrial function seemed to be upregulated due to adipocyte dicer deficiency, indicated by increased protein levels of OXPHOS components and PGC1α. In line, mitochondria repressors FOXO1 and FOXO3 were phosphorylated and inactivated, whose downstream antioxidant targets Catalase and Sod were also decreased. Moreover, P16, a marker of senescence, exhibited a trend to be increased due to adipocyte dicer deficiency. Since mitochondrial ROS surplus can lead to DNA damage and senescence, we assured that adipocyte dicer deficiency might induce a combination of mitochondrial activation and reduction in detoxification reduction possibly mediated by the inactivation of FOXO1 and FOXO3a. Finally, the result that nutrient restriction positively regulated dicer level in adipocytes further supported that there is a conserved aging pathway in adipocytes involving dicer. On the other part, through microarray screen and RT-qPCR validation, we reported that aging increased mir-1949 in adipocytes in wild type mice and possibly promoted its secretion from perigonadal adipose tissue in vitro. Correspondingly, in vitro results also suggested that senescence increased mir-1949 production and secretion from adipocytes. Functionally, upregulation of mir-1949 in 3T3-F442A adipocytes negatively regulated mitochondrial complex II protein level and oxygen consumption capability, associated with lipid accumulation. Interestingly, sustained upregulation of mir-1949 during adipogenesis of 3T3-F442A preadipocytes, tended to increase white adipocyte markers, such as Leptin, Glut4 or Hsl. Finally, combined with the results that 24h fasting significantly increased mir-1949 in perigonadal adipose tissue as well as that upregulation of mir-1949 exhibited a trend to increase lipid accumulation in senescent 3T3-F442A adipocytes, we assured that aging increases mir-1949 expression in adipocytes which might try to rescue age-related dysfunctions in adipocytes, such as impaired lipid storage. Nevertheless, the precise actions of mir-1949 need to be validated in vivo by injection of AAV-aP2-mir-1949 mimic into aged mice

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Pons, Mercadé Pere. "Yeasts autolysis on the manufacture of sparkling wines; Influence of aging time on the release of polysaccharides and proteins and the consumption of oxygen by the lees." Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/672221.

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El cava és un vi escumós produït seguint mètode tradicional que consisteix en dues fermentacions. En la primera, el suc de raïm es transforma en un vi base segons un procés de vinificació estàndard. Quan s’acaba la segona fermentació, els vins escumosos s’envelleixen a l’ampolla en contacte amb llevats (mares) durant un temps determinat, durant el qual té lloc el procés d’autòlisi. Durant aquest temps de criança, les mares alliberen macromolècules al vins modulant la composició final i la qualitat. A més, també es creu que les mares tenen un efecte protector en contra l’oxidació. Per aquest motiu, els viticultors asseguren que aquest llarg contacte amb les mares és la principal diferència entre els vins escumosos produïts pel mètode tradicional (o méthode champenoise) i els produïts per altres procediments. En base a aquesta hipòtesi, es va caracteritzar l’autòlisi del llevat en el vi escumós produït per mètode tradicional (Cava) durant un llarg temps d’envelliment dins de l’ampolla (9 anys) mitjançant: quantificació dels polisacàrids i proteïnes alliberats per les mares durant un llarg temps d’envelliment, l’evolució de les característiques sensorials, propietats de color i escuma, controlant la degradació visual del llevat durant el temps d’envelliment mitjançant microscòpia electrònica d’escombratge (SEM) i quantificant l’impacte dels polisacàrids i les proteïnes alliberades per mares en la composició total de les macromolècules dels vins escumosos. Després, es va quantificar la capacitat de consum d’oxigen (OCR) de les mares dels Caves i la seva variació al llarg del temps de criança. Després de confirmar que les mares consumeixen oxigen, es va establir un tercer estudi per confirmar i comprendre millor els mecanismes de l’efecte protector contra l’oxidació per llevats secs inactivats (IDY). Aquests OCR es van comparar amb els antioxidants més comuns utilitzats en l'elaboració del vi: el diòxid de sofre, l’àcid ascòrbic i el glutatió.
El cava es un vino espumoso producido siguiendo el método tradicional que consiste en dos fermentaciones. Cuando se termina la segunda fermentación, los vinos espumosos se envejecen en la botella en contacto con levaduras (lías) durante un tiempo determinado, durante el cual tiene lugar el proceso de autolisis. Durante este tiempo de crianza, las lías liberan macromoléculas al vino modulando la composición final y la calidad. Además, también se cree que las lías tienen un efecto protector en contra la oxidación. Por este motivo, los enólogos aseguran que este largo contacto con las lías es la principal diferencia entre los vinos espumosos producidos por el método tradicional (o méthode champenoise) y los producidos por otros procedimientos. En base a esta hipótesis, se caracterizó la autolisis de la levadura en el vino espumoso producido por método tradicional (Cava) durante un largo tiempo de envejecimiento dentro de la botella (9 años) mediante: cuantificación de los polisacáridos y proteínas liberados por las madres durante el tiempo de envejecimiento, la evolución de las características sensoriales, propiedades de color y espuma, evaluando la degradación visual de la levadura durante el tiempo de envejecimiento mediante microscopía electrónica de barrido (SEM) y cuantificando el impacto de los polisacáridos y las proteínas liberadas por las lías en la composición total de las macromoléculas de los vinos espumosos. Después, se cuantificó la capacidad de consumo de oxígeno (OCR) de las lías de los Cavas y su variación a lo largo del tiempo de crianza. Tras confirmar que las lías consumen oxígeno, se estableció un tercer estudio para confirmar y comprender mejor los mecanismos del efecto protector contra la oxidación por levaduras secas inactivados (IDY). Estos OCR se compararon con los antioxidantes más comunes utilizados en la elaboración del vino: el dióxido de azufre, el ácido ascórbico y el glutatión.
Cava is a sparkling wine produced by the traditional method which involves two fermentations. In the first fermentation the grape juice is transformed into a base wine according to a standard winemaking process. When the second fermentation is complete, the sparkling wines are aged in the bottle in contact with yeast (also called lees) for a certain length of time, during which the process of autolysis takes place. During this ageing time, lees release macromolecules to sparkling wine matrix modulating the final composition and the quality of Sparkling wines. In addition, it is also thought, that lees enable to age longer due to their protective effect against oxidation. For this reason, winemakers say that this long contact with lees are the main difference between sparkling wines produced by the traditional method (or méthode champenoise) and those produced by other procedures. In basis of these hypothesis, a characterization of yeast autolysis in sparkling wine produced by traditional method (Cava) over long aging time inside the bottle (9 years) by: quantification of the polysaccharides and protein, following the evolution of the sensory characteristics, color and foaming properties, monitoring visual degradation of yeast over aging time using Scanning Electron Microscopy (SEM) and quantify the impact of the lees released polysaccharide and proteins in the total sparkling wine macromolecules composition. Then, an evaluation of the oxygen consumption capacity (OCR) of lees of sparkling wine elaborated by traditional method and its variation over long aging time. Furthermore, after confirming that lees really consume oxygen, a third study were set in order to confirm and understand better the mechanisms of the protective effect against oxidation by inactivated dry yeast (IDY). These OCRs were compared with the most common antioxidants used in winemaking: sulfur dioxide, ascorbic acid and glutathione to evaluate their effectiveness.

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Hodzik, Suzanne. "Rôle des fonctions exécutives dans les variations stratégiques au cours du vieillissement." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10054.

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La plupart des travaux empiriques ont montré que les jeunes et les âgés utilisent de nombreuses stratégies pour accomplir des tâches cognitives. Ils mettent aussi en évidence que les âgés (a) utilisent moins de stratégies, (b) utilisent les stratégies disponibles dans des proportions différentes, (c) exécutent moins efficacement les stratégies utilisées, et (d) choisissent, sur chaque problème, moins fréquemment la meilleure stratégie que les jeunes. L’objectif général de cette thèse était de déterminer quels sont les mécanismes sous-tendant la différence de performances jeunes/âgés dans ces différentes dimensions stratégiques. Nous testons l’hypothèse que le déclin des fonctions exécutives médiatise les différences liées à l’âge dans le répertoire, la distribution, l’exécution et la sélection stratégiques. Pour atteindre cet objectif, nous avons adopté une approche corrélationnelle et une approche expérimentale. Les résultats répliquent les principales données concernant les différences jeunes/âgés dans les différentes dimensions stratégiques. De plus, ils mettent en évidence le rôle essentiel des fonctions exécutives, et, en particulier, de la flexibilité cognitive et de l’inhibition, dans la diminution avec l’âge du répertoire, de la sélection et de l’exécution stratégiques. Nous discutons les implications de ces résultats sur le vieillissement et les variations stratégiques, d’une part, et sur les modèles de la sélection stratégique, d’autre part
Empirical studies on strategic variations during aging have shown that young andolder adults use multiple strategies to accomplish cognitive tasks. They also showed that older adults (a) use fewer strategies, (b) do not use available strategies with the same frequency as young adults (c) execute strategies less efficiently, and (d) select less frequently the best strategy than young adults. The aim of this study was to investigate which mechanisms underly the strategic differences in young and older adults. We tested the hypothesis that age related decline of executive functions mediate age-related differences in strategy repertoire, distribution, execution, and selection. To achieve these ends, we adopted correlational and experimental approaches. Results replicated previous data relative to differences between young and older adults in different strategy dimensions. Results also highlight crucial role ofexecutive functions, especially cognitive flexibility and inhibition, in strategy repertoire, selection, and execution. Implications for further our understanding of aging and strategic variations, as well as current theoretical models of strategy selection are discussed

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Gritsaenko, Tatiana. "Modifications de la matrice extracellulaire osseuse dans des conditions pathologiques ou environnementales : caractérisation et conséquences sur les cellules osseuses." Electronic Thesis or Diss., Université Côte d'Azur (ComUE), 2019. http://theses.univ-cotedazur.fr/2019AZUR6034.

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Le tissu osseux est soumis à un remodelage constant au cours duquel les ostéocytes font office de mécanorécepteurs et coordonnent l’activité des ostéoclastes (OCL) qui résorbent le tissu osseux, et des ostéoblastes (OB) qui synthétisent la matrice extracellulaire (MEC) minéralisée. L’objectif de mon projet de thèse était d’étudier les altérations des matrices osseuses induites par certaines conditions physiopathologiques ou environnementales et d’explorer leurs effets sur le comportement des cellules osseuses et sur le tissu osseux. Dans la première partie du projet, j’ai étudié en tant que modèle de pathologie osseuse, des souris dont le gène Recql4, une ADN hélicase, a été inactivé. Chez l’homme, les mutations du gène RECQL4 sont responsables du syndrome Rothmund Thomson de type II associé à différentes anomalies squelettiques dont une perte osseuse prématurée. Dans un premier temps, j’ai caractérisé le phénotype osseux des souris Recql4 / et constaté un vieillissement osseux prématuré chez ces animaux. Ensuite, j’ai analysé ex vivo le comportement des OB et OCL primaires isolés de souris Recql4 / . Nous avons observé que la MEC produite par les OB Recql4 / tend à être moins minéralisée et est significativement plus rigide que la MEC synthétisée par les OB témoins. La perte d’élasticité de la MEC dans le cas du tissu osseux serait associée à une stimulation de la résorption. Ceci corrobore nos analyses histologiques qui révèlent une augmentation de la surface osseuse couverte par les OCL chez les souris mutantes. L’analyse protéomique de matrices synthétisées ex vivo par des OB Recql4 / ou des OB contrôles, a permis l’identification de 204 protéines différentiellement exprimées. Ces résultats étayent l’hypothèse selon laquelle les OB Recql4 / synthétisent une matrice osseuse modifiée. Parmi ces protéines, je me suis focalisée sur celles connues pour être impliquées dans l’organisation de la matrice et/ou la communication cellule matrice. Ces travaux serviront de point de départ à des études à venir visant à explorer l’implication de ces protéines candidates dans la perte osseuse provoquée par la perte de RECQL4 et à examiner le comportement des cellules osseuses sur la MEC modifiée Recql4 / .La deuxième partie de ma thèse concerne l’effet de l’uranium naturel (U) piégé dans la matrice sur les cellules osseuses. L’U est un métal lourd naturellement présent dans l’environnement, qui possède un faible niveau de radioactivité mais une toxicité chimique importante. La matrice osseuse est le principal site de rétention de l’U à long terme dans l’organisme. Cet actinide perturbe le métabolisme de l’os, mais son mode d’action et ses effets sur les cellules osseuses, notamment les OCL, n’est pas connu. J’ai d’abord montré que la présence d’U dans le milieu de culture des OCL stimule ou inhibe la fonction de ces cellules, selon la concentration. J’ai ensuite examiné l’effet de l’U incorporé à la matrice sur les OCL. À cette fin, nous avons développé deux systèmes modèles : une surface osseuse synthétique biomimétique sur laquelle l’U a été adsorbé, et des matrices « biologiques » synthétisées par des OB cultivés en présence d’U. A l’aide de ces modèles, nous démontrons pour la première fois que l’U intégré à la matrice peut être remobilisé par la résorption ostéoclastique. De plus, nos données suggèrent que l’U libéré par résorption pourrait stimuler l'ostéoclastogenèse.En conclusion, mes travaux ont conduit à la caractérisation d’un nouveau modèle murin de vieillissement prématuré des os et à la première démonstration de l’effet de l'uranium sur le comportement des ostéoclastes. Ce travail illustre l’importance que peuvent avoir les altérations de la MEC osseuse sur la fonction des cellules osseuses. En outre, la mise au point de systèmes de culture 3D de cellules osseuses qui miment les microenvironnements osseux normaux ou défectueux sera utile pour identifier de nouveaux mécanismes de la physiopathologie osseuse
Bone tissue undergoes constant remodeling during which osteocytes, cells acting as mechanosensors, coordinate the function of osteoclasts (OCL), resorbing old and damaged bone, and of osteoblasts (OB), synthesizing new mineralized extracellular matrix (ECM). In addition to serving as a support for mineral deposits, the protein network of bone ECM is involved in regulating the behavior of bone cells by modulating their proliferation, differentiation and/or function. The aim of my thesis project was to study bone matrix alterations induced by various pathological or environmental conditions and to explore their consequences on bone cell behavior and/or on bone health.In the first part of my project, RECQL4 deficient mice were used as a model of bone pathology. In humans, bi allelic mutations in the RECQL4 gene, a DNA helicase, are responsible for type II Rothmund Thomson syndrome (RTS II), a rare progeroid disorder associated with a range of skeletal anomalies, including premature bone loss. We first characterized the bone phenotype of Recql4 / mice. We found that bone loss associated with normal aging is accelerated and more pronounced in Recql4 / animals. Next, we performed ex vivo experiments using primary bone cells (OCL and OB) from elderly mice. ECM produced by Recql4 / OB tends to be less mineralized and is significantly stiffer compared to control ECM, suggesting osteoblast dysfunction. Stiffening of ECM is a general feature of aging tissue and is believed to promote bone resorption. This is consistent with our histological data, which show increase in bone surface covered by the OCL in Recql4 / mice compared to control. Proteomic analysis of ECM enriched extracts derived from Recql4 / and Recql4+/ primary OB identified 204 differentially expressed proteins, supporting the hypothesis that Recql4 / OB synthesize a modified bone matrix. Among these proteins, we focused in particular on those important for matrix organization as well as for cell matrix communication. Additional studies are now necessary to explore their possible implication in the accelerated bone loss seen in RECQL4 deficient mice and to examine the behavior of bone cells on Recql4 / bone ECM.A second part of my thesis work was aimed at evaluating the effect of natural uranium trapped in the bone matrix on bone cells. Uranium (U) is a naturally occurring heavy metal widespread in the environment. While its radioactive activity is low, uranium exhibits a strong chemical toxicity. The bone matrix is the main site of U long term retention. In vivo and epidemiological studies have shown that natural U impairs bone metabolism. However, the mechanism of its action and its effects on bone cells, in particular on osteoclasts, remain largely unexplored. We examined for the first time in vitro the effects of natural U on osteoclasts. We first showed that the presence of U in the culture medium stimulates or inhibits osteoclastic function, depending on the U concentrations used. We then examined the effect of U immobilized in bone like matrices on OCL. For this purpose, we developed two model systems: a bone synthetic biomimetic surface onto which U has been adsorbed and “biological” matrices synthetized by OB cultured in the presence of U. By using these models, we demonstrated for the first time that embedded U can be remobilized from the matrix through osteoclastic resorption. Moreover, our data suggest that U released by resorption could stimulate osteoclastogenesis. In conclusion, my work led to the characterization of a new mouse model of premature bone aging, and provided the first evidence of the effect of uranium on osteoclast behavior. In doing so, this work illustrates the importance of bone matrix alterations on bone cell function. In addition, the development of three dimensional bone cell culture systems that mimic normal or defective bone microenvironments will be useful in identifying new mechanisms essential to bone health

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Bigo, Mathilde. "Les pratiques des femmes âgées sur les promenades balnéaires en Bretagne : processus de vieillissement et citadinité." Thesis, Rennes 2, 2015. http://www.theses.fr/2015REN20002/document.

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En France comme dans la plupart des pays du Nord, les personnes âgées représentent une part de plus en plus importante de la population.Parmi elles, les femmes sont les plus nombreuses, et plus encore au fur et à mesure de l’avancée en âge. La féminisation de la population âgée pose des enjeux importants.Elle impose de s’interroger sur la place faiteaux femmes âgées dans notre société. L’objet de la présente thèse est de s’y attacher sous l’angle spécifique des pratiques des femmes âgées sur les promenades de bord de mer. Ces espaces singuliers ont été choisis pour questionner la citadinité. Caractérisant le rapport à la ville exprimé par les pratiques des individus quant à l’appropriation de l’espace,l’ancrage et les sociabilités, la citadinité permet de caractériser l’inclusion de la personne âgée dans la société et, notamment, de voir comment le processus de vieillissement fait son oeuvre dans ces dynamiques d’inclusion.Espaces ressource pour « faire ville » avec les autres, pour la réalisation de soi à l’heure de la retraite, pour continuer à « se tenir face au monde » au grand âge, les promenades balnéaires sont des terrains d’exploration éminemment riches pour appréhender la citadinité des femmes âgées et donc leur inclusion en ville. Au regard du parcours de vie(familial, professionnel, résidentiel), l’analyse des pratiques des femmes âgées a notamment montré une diversité de modes d’inclusion à l’espace. Le recours à la notion de déprise, qui rend compte de l’évolution des pratiques de l’espace au cours de la vieillesse en mettant en lumière ce sur quoi les individus « lâchent prise » et « gardent prise », permet de poser la question du maintien de l’inclusion sociale dans la ville. Par les possibilités de prise qu’elle offre aux femmes vieillissantes, la promenade est un espace ressource pour réajuster les pratiques au fur et à mesure que la déprise le suggère, et, par là, pour maintenir la citadinité. Elle permet de continuer à s’exprimer à travers les pratiques, mais dans des formes différentes, selon que la recherche de sociabilités, de grand air, d’indépendance,d’autonomie, d’imprévu, est constitutive de la citadinité des femmes, à travers les âges
As in many Northern countries, the elderly population in France represents an important increasing part of the population. Generally there are more elderly women than men, and this number increases, as the elderly women get even older. The feminisation of the elderly population raises important issues. It leads one to reflect on the position provided to older women in our society. The goal of this thesis is to look at the specific practices of elderly women on seaside promenade. This spaces are chosen to question citadinité. Examining the relationship between the community and the behaviors of these women, regarding their required space, their anchor and their sociability, the citadinité assess the inclusion of the elderly persons in the society. It helps,especially, to see how the process of aging works in these dynamics of inclusion.Strolls on waterfronts allows the use of space with others, one’s self realization when facing retirement, and the drive to still be an active participant as one ages. These waterfront walksare rich fieldworks to grasp the assimilation of the aged women’s citadinité with their inclusion in the community. Looking at the life course of elderly women (familial,professional, residential), the analysis has shown a grand diversity of modes of inclusion in relation to the space. The application of the notion of déprise, a form of disengagement which looks at the evolution of use of space ,through aging showing on what people « give up » and « hold on», allows to investigate the level of maintenance of social inclusion in the community. Through these characteristics, waterfront walks offers to aging women a resourceful space to readjust practices as the disengagement suggests it, allowing the maintenance of the citadinité. The waterfront walk allows, through the practices, to express oneself, but in various forms as long as the search for social relationships, fresh air,independence, autonomy, novelty, have the power to establish the women’s citadinité through aging

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Pistono, Aurélie. "Exploration du discours dans le vieillissement typique et la maladie d'Alzheimer : liens avec les modifications neurocognitives sous-jacentes." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30147/document.

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Le langage demeure préservé des effets du vieillissement mais précocement atteint dans la Maladie d'Alzheimer (MA). Le discours, en mobilisant l'ensemble des fonctions cognitives, pourrait mettre en évidence davantage de difficultés. Ce travail vise à analyser des productions de patients et de participants âgés typiques en lien avec les changements cognitifs et cérébraux. Une étude s'est intéressée à la production de discours portant sur des événements personnellement vécus. Une deuxième visait à comparer ce type de discours à un discours sur support imagé. Les résultats montrent que les difficultés rencontrées lors d'un discours d'événements vécus seraient corrélées à l'atteinte mnésique des patients. A l'inverse, elles seraient associées à l'atteinte exécutive et lexicale dans un discours imagé. Une dernière étude s'est focalisée sur la variabilité existant chez les participants âgés "typiques". Une analyse en cluster a montré quatre profils de locuteurs, dont un profil "hors-sujet" qui pourrait refléter une zone ambiguë entre vieillissement normal et pathologique. Ce travail pointe des marqueurs de MA prodromale, en lien avec les modifications cognitives et cérébrales. Certaines difficultés seraient liées à une atteinte mnésique ou exécutive indépendamment de l'altération langagière
Language is the most preserved cognitive function from the effects of aging. Unlike typical aging, Alzheimer's disease (AD) is characterized by an early impairment. Analysis of discourse may reveal more difficulties than other tests since it mobilizes a large set of cognitive functions. This work aims to analyze various discourses in AD patients and participants with typical aging, in relation to various cognitive tests as well as neuroimaging data. One study focused on a memory-based discourse. A second study compared a memory-based and in a picture-based discourse. Patients' difficulties were correlated on one hand with memory impairment in the memory-based discourse and on the second hand with lexical-executive impairment in the picture-based discourse. A final study focused on discourse variability in the general aging population. A cluster analysis revealed four profiles of speakers. Among them, an "off-topic" profile could reflect a grey zone between normal and pathological aging. This work allowed us to shed light on deficit markers and compensatory strategies in prodromal AD, in relation with cognitive and cerebral changes. In particular, many difficulties may actually be related to memory or executive impairment, regardless of a language alteration

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DePianto, Daryle Joseph. "Studies on lens fiber cell gene expression & lens differentiation /." Connect to Digital dissertations. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.

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Gao, Weichuan, and Jose Sasian. "Air lens vs aspheric surface: a lens design case study." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/627181.

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We discuss the behavior of air lenses in lens design. The structural aberration coefficients of a thin air lens are derived and compared with their glass thin lens counterpart. Examples are provided for a telephoto lens and the Monochromatic Quartet where air lenses or aspheric surfaces are used.

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Yang, Dingjie. "The Network Lens." Thesis, Linnaeus University, School of Computer Science, Physics and Mathematics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-6626.

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A complex network graphics may be composed of hundreds and thousands of objects, such as nodes and edges. Each object may hold a large number of attributes that might be difficult to explore in the network visualization. Therefore, many visualization tools and approaches have been developed to gain more information from the network graphics. In this paper, we introduce the concept of the Network Lens, a new widget that assists the users to deal with a complex network. The Network Lens is an interactive tool that combines data visualization to a magic lens. With the help of the Network Lens, users can display hidden information of the elements in the network graphics based on their interest. Moreover, the Network Lens supports a series of interactive functions that give the users flexible options to define their own lenses.

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Shepard, III Ralph Hamilton. "Metamaterial Lens Design." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/194734.

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Developments in nanotechnology and material science have produced optical materials with astonishing properties. Theory and experimentation have demonstrated that, among other properties, the law of refraction is reversed at an interface between a naturally occurring material and these so-called metamaterials. As the technology advances metamaterials have the potential to vastly impact the field of optical science.In this study we provide a foundation for future work in the area of geometric optics and lens design with metamaterials. The concept of negative refraction is extended to derive a comprehensive set of first-order imaging principles as well as an exhaustive aberration theory to 4th order. Results demonstrate congruence with the classical theory; however, negative refraction introduces a host of novel properties. In terms of aberration theory, metamaterials present the lens designer with increased flexibility. A singlet can be bent to produce either positive or negative spherical aberration (regardless of its focal length), its contribution to coma can become independent of its conjugate factor, and its field curvature takes on the opposite sign of its focal power. This is shown to be advantageous in some designs such as a finite conjugate relay lens; however, in a wider field of view landscape lens we demonstrate a metamaterial's aberration properties may be detrimental.This study presents the first comprehensive investigation of metamaterial lenses using industry standard lens design software. A formal design study evaluates the performance of doublet and triplet lenses operating at F/5 with a 100 mm focal length, a 20Â° half field of view, and specific geometric constraints. Computer aided optimization and performance evaluation provide experimental controls to remove designer-induced bias from the results. Positive-index lenses provide benchmarks for comparison to metamaterial systems subjected to identical design constraints. We find that idiosyncrasies in a metamaterial lens' aberration content can be exploited to produce imaging systems that are superior to their conventional counterparts. However, in some circumstances the reduced low-order aberration content in a metamaterial lens reduces the effectiveness of aberration balancing and stop shifting. Through a series of design experiments the relative advantages and challenges of using metamaterials in lens design are revealed.

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Weir, I. J. M. "The thermal lens." Thesis, University of Strathclyde, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372116.

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Crouch, Izzy. "Beyond the Lens." Scholarship @ Claremont, 2019. https://scholarship.claremont.edu/scripps_theses/1245.

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Beyond the Lens is a portrait series combining visual images with audiotaped recordings of eight Scripps seniors’ narration of their personal, academic and interpersonal process during the course of their college career. This capstone project seeks to uncover the dynamic nature of the Scripps College community by highlighting the unique evolution of these eight individuals. With this project, I hope to convey that while there is no one specific mold for a Scripps student, there are common threads in the development of key characteristics which propel these participants toward their next steps, among them courage to pursue leadership roles, compassion for underrepresented groups both locally and globally, confidence to make positive changes in their fields of interest and a profound engagement and commitment to their immediate and extended communities. Beyond the Lens not only guides the viewer into the makings of each of these student’s individual profiles but also helps the viewer understand better how the Scripps community shapes their personal ambitions, creating fertile ground for lasting impact. Through the interview process, I examine the enduring imprint of an historically all-women’s college environment, exploring disparate and common threads within each student's experiences, including the effects of in-depth exploration and articulation of multiple perspectives and theoretical positions within academic and non-academic exchanges. Moreover, in these conversations, I ask each student to consider both positive and negative elements of their community and to reflect on their holistic experience at the College in and outside of the classroom. While this capstone is a minute representation of the Scripps community as a whole, it nonetheless provides a glimpse into the influences and processes at play within Scripps College. I aim to demonstrate that being a Scripps student means that we, as a community, are pressed to delve beyond the limited representations so pervasive in our current media soaked lives toward a more complex understanding of ever-evolving forces that occur within ourselves, other members of our community and society at large.

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Amador, Lui. "Deslanting the Lens." Scholarship @ Claremont, 1999. http://scholarship.claremont.edu/cgu_etd/93.

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Deslanting the Lens examines the historical and sociological implications of how Asian men have been represented in popular American film. From the early days of “yellowface” to caricatures like Long Duck Dong, Asian men have been relegated to perpetual foreigner status in American cinema. This paper will explore why the portrayal of Asian men has been limited to very specific ideas about Asian and Asian Americans are in society. This analysis will also include how socio/political events have shaped and influence popular perceptions about Asians, that inform how Asian men continue to be depicted in film.

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Ghosn, Ramy. "Stabilisation des Fluides de Forage de Type Pickering Pour Applications dans les Forages Profonds et Ultra-Profonds." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLY022/document.

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La situation durable de volatilité des prix du pétrole est considérée à la fois comme une menace et un défi par l'industrie pétrolière. Au cours de cette crise, les compagnies pétrolières ont l’opportunité de se recentrer sur la recherche de solutions de production rentables, ce qui implique souvent l’apport des nouvelles technologies, en plus de l'amélioration des processus.Ce travail présente une avancée pour la synthèse d’une nouvelle génération de fluides de forage pétrolier sans surfactants/émulsifiants pour des applications dans le forage des puits profonds et ultra profonds. Cette nouvelle génération repose sur l’introduction des émulsions de Pickering dans la formulation des fluides de forage. Ces dernières sont des émulsions stabilisées uniquement par des particules solides (dans ce cas des particules de silice). Différents types de nano particules de silice de différentes hydrophobicités ont été utilisées pour stabiliser des fluides de forage de types huile-dans-eau et eau-dans-huile. Ces fluides ont été conçus pour être utilisés dans des conditions hostiles de température et de pression. Par conséquent, une caractérisation expérimentale de leur stabilité ainsi que de leurs propriétés rhéologiques sous ces conditions extrêmes étaient nécessaires. Au cours de ce travail, les profils rhéologiques de ces fluides reflétant leurs capacités de nettoyage du puits, leur coulabilité ainsi que leurs capacités à transporter les débris jusqu'à la surface, ont été établis. D’autre part, la stabilité électrique des émulsions ainsi que leur morphologie (distribution de taille des gouttelettes) ont été étudiées et une comparaison avec celles stabilisées par des agents tensioactifs a été établie. Les fluides ont été exposés à un processus de vieillissement qui permet d’étudier l'effet de l'environnement du réservoir hostile sur la stabilité et la rhéologie des nouveaux fluides préparés. Ces fluides de haute qualité se sont révélés très fiables, offrant une grande stabilité et une capacité à résister à des conditions extrêmes de réservoir. Ils représentent une nouvelle génération de fluides de forage ouvrant la voie à une exploitation optimisée de réservoirs profonds et ultra profonds
This enduring situation of volatile oil prices has been seen as a decline and a challenge at the same time for the oil and gas industry. It is during this slump that the oil and gas companies own the opportunity to focus on cost-effective production solutions, which very often means bringing new technologies and further improving processes.This work presents a novel frontier of surfactant-free drilling and completion fluids for deep and ultra-deep wells. This new generation of drilling fluids is based on the principle of Pickering emulsions (emulsions stabilized solely by solid nano particles). Hydrophobic and hydrophilic silica nano particles were used to stabilize Oil-Based Mud and Water-Based Mud. These fluids were designed to be used under hostile conditions of temperature and pressure. Therefore, a concrete characterization of their stability as well as their rheological properties under HTHP conditions was mandatory. Rheological profiles reflecting the flowability, hole cleaning capacity as well as cutting transport ability of the fluids were established. On the other hand, the electrical stability as well as the morphology (Droplet Size Distribution) of the emulsions were studied and compared with surfactant-stabilized drilling fluids. The fluids were submitted to an aging process allowing one to study the effect of hostile reservoir environment on the stability and rheology of the new fluids prepared.These high quality fluids were seen very reliable offering high stability as well as high capacity to withstand extreme reservoir conditions giving rise to a new generation of drilling fluids allowing breaking the frontiers of deep and ultra-deep reservoirs

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Poletti, Céline. "Les variations stratégiques dans les tâches cognitives et motrices au cours du vieillissement." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM3102.

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Des travaux récents ont montré que les relations entre le fonctionnement cognitif et sensori-moteur étaient de plus en fortes au cours du vieillissement, suggérant que des mécanismes communs seraient responsables du déclin avec l’âge des performances cognitives et sensori-motrices. Des variations quantitatives telles que la diminution avec l’âge de la vitesse de traitement ont été proposées comme cause commune pour expliquer le ralentissement cognitif et sensori-moteur. Toutefois, nous ignorons toujours comment ces variations quantitatives pourraient influencer les variations qualitatives au cours du vieillissement. L’objectif de cette thèse était de décrire les variations stratégiques liées à l’âge dans le domaine sensori-moteur d’une part, et de déterminer si les variations stratégiques observées dans le domaine cognitif pouvaient être communes aux variations stratégiques dans le domaine sensori-moteur, d’autre part. Nos données répliquent les principaux résultats observés dans les domaines cognitifs concernant les différences liées à l’âge dans les différentes variations stratégiques ainsi que les phénomènes associés à des variations telles que les effets de difficulté séquentielle, suggérant l’implication de ressources communes telles que les fonctions exécutives. Nos données montrent également une amplification de ces variations stratégiques au cours du vieillissement pathologique et suggèrent une amélioration de l’exécution stratégique après un entraînement. Les résultats présentés dans cette thèse permettent une meilleure compréhension des mécanismes cognitifs sous-jacents au comportement sensori-moteur des adultes jeunes et âgés durant la tâche de Fitts
Recent studies have demonstrated that the relationship between cognitive and sensori-motor functioning is becoming stronger during aging, suggesting that common mechanisms could be responsible for age-related decline in cognitive and sensori-motor performance. Quantitative variations in aging, such as decreased information processing speed have been proposed as a common cause to explain cognitive and sensori-motor slowing. However, we do not know how these quantitative variations can influence the qualitative changes during aging. The main objective of this thesis was to describe age-related strategic changes in the sensori-motor domain and furthermore to determine whether these strategic changes in the sensori-motor domain share similar strategic variations with cognitive domain. To achieve this objective, a total of five studies were conducted where both young and older adults performed the Fitts' task. Our data replicated previous findings relative to those observed in the cognitive domain. On the one hand, age-related differences in strategy repertoire, strategy distribution and strategy execution were found. On the other hand, phenomenon associated with these variations, such as strategy sequential difficulty effects were also observed, suggesting involvement of common resources (i.e., executive functions). Additionally, we showed an amplification of these strategic variations in pathological aging and an improvement in strategic execution after training. These results provide a better understanding of the underlying cognitive mechanisms in young and older adults’ sensori-motor behavior during the Fitts’ task

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Karami, Elham. "Effet de traitements thermiques modérés et de revêtement sur les propriétés vibratoires des bois d’Epicéa et de Mûrier." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT340/document.

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Le bois est couramment utilisé pour la fabrication d’instruments de musique. Les procédés employés consistent souvent en traitements modifiant le matériau en volume ou en surface. Ce travail s’est focalisé sur deux espèces employées dans les instruments à cordes et représentatives de différentes cultures: L’épicéa (Picea abies Karst.) utilisé en Europe et le Mûrier blanc (Morus alba L.) utilisé en Iran. Pour chacune l’effet d’un traitement thermique modéré (<150°C) et d’un revêtement par vernis sur plusieurs propriétés physiques et mécaniques ont été étudiés. Les principaux résultats sont les suivants. A la différence de l’Epicéa, le Mûrier présente un très faible degré d’anisotropie mécanique. Chez les deux espèces, le traitement thermique entraîne une forte chute dde l’amortissement, particulièrement dans la direction radiale pour l’Epicéa, ainsi que du taux d’humidité d’équilibre, sans dégradation marquée comme indiqué par la faible perte de masse. Toutefois, après reconditionnement à haute humidité, une part importante de la modification est récupérée. L’application d’un vernis à base solvent sur le Mûrier entraîne une rigidification continue, tandis que la forte augmentation de l’amortissement observée après l’application est suivie par un retour au bout d’environ 2 mois aux niveau du bois non traité. Pour l’Epicéa, des vernis à base d’huile siccative ont été appliqués et divers paramètres du procédé ont été testé. Dans ce cas la cintétique de stabilisation des propriétés est très lente et des variations notables continuaient à être observée au bout de 5 mois
Wood is commonly used for making musical instruments. During the process it is often subjected to treatments, that either modify its volume or its surface properties. Two species used for for string instruments were studied, representative of different cultures: Spruce (Picea abies Karst.) used in Europe and White Mulberry (Morus alba L.) used in Iran. For each of them the effect of thermal treatment at moderate temperature (<150°C) and of coating on various physical and mechanical properties was studied. The main results are as follows. In contrast to Spruce, Morus has a very low degree of mechanical anisotropy. For both species, thermal treatment induces a strong decrease in damping, especially in R direction for Spruce, and equilibrium moisture content, without marked degradation as indicated by the very small weight loss. However, after reconditioning at high humidity, a significant part of the changes is recovered. The application of a solvent-based varnish on Morus induces a continuous stiffening, while a very strong increase in damping after application is followed, after about 2 months, by a return to values close to those of untreated wood. For Spruce, siccative oil based varnish was applied and several parameters of the process were tested. In this case, the kinetics of property stabilisation are very slow and significant changes were still observable after 5 months

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Pinos, Andrea. "Optical properties and degradation of deep ultraviolet AIGaN-based light-emitting diodes." Doctoral thesis, KTH, Fotonik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-37917.

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Navaux, Julien. "Les transferts intergénérationnels en France : stabilités et ruptures des répartitions entre classes d'âge." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLED021.

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Cette thèse a pour objectif de vérifier si les baby-boomers sont à l’origine d’une rupture de l’équité intergénérationnelle en France. Elle repose sur une application de la méthode des Comptes de Transferts Nationaux, ce qui permet d’obtenir une mesure par âge de la consommation, des ressources individuelles, de l’épargne et des transferts publics et privés entre 1979 et 2011. Des projections sont également réalisées à l’horizon de l’année 2060 grâce au modèle MELETE concernant les transferts publics reçus et le revenu disponible. Les résultats, qui sont établis au regard des principaux critères de justice intergénérationnelle, ne présentent pas de rupture manifeste et généralisée de l’équité entre générations, même si la société française se caractérise par certaines iniquités concernant la répartition des revenus d’actifs et la répartition des pensions de retraite entre générations. Par ailleurs, cette thèse apporte des résultats qui sont utiles à la compréhension de la solidarité familiale en France. Depuis trente ans, l’augmentation du poids économique des donations et des héritages coïncide avec une diminution du poids des aides en sein des ménages et une stabilité du poids des aides entre ménages. Il en résulte que les transferts privés entre ménages sont de moins en moins adaptés aux besoins des bénéficiaires, ce qui est corroboré par une analyse micro-économétrique en panel qui montre que les évènements vécus par les donateurs peuvent déclencher le versement de donations, contrairement aux aides entre ménages qui dépendent exclusivement des évènements vécus par les donataires
The purpose of this dissertation is to asses if baby-boomers are responsible of intergenerational inequities in France. To answer this research question, the dissertation applies the National Transfer Accounts (NTA) methodology to the case of France, for the time period covering 1979-2011, therefore capturing national accounts aggregates such as consumption, individual resources, savings and transfers by age. Projections are conducted up to 2060 for public transfers inflows and for disposable income using the computable general equilibrium model “MELETE”, and the results are drawn from the main criteria of intergenerational justice. The results of this dissertation show that there is no obvious and widespread disruption of fairness between generations in the country. However, France is still characterized by intergenerational inequities seen through the allocation of asset income and publics pensions. The NTA methodology also provides useful results about private transfers in France. Since 1979, the role of wealth transfers increased over time, whereas the role of private transfers within households (intra-household transfers) decreased over this period and the role of regular, occasional and in-kind transfers between household (inter-household transfers) remained stable. It follows that private transfers are less and less responsive to the needs of transfer recipients. In fact, a micro econometric analysis using panel data shows that the life events experienced by transfer givers can trigger the payment of inter vivos wealth transfers, which is not the case for inter-household transfers that depend exclusively on the life events experienced by the recipients

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Dissertations / Theses on the topic 'Aging of the lens'

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