<p> Ageism, or discrimination based on assumptions about abilities and cognitive understanding based on a worker&rsquo;s age, still prevails in the modern workplace, often disguised as business decisions, lack of advancement opportunities, and continuing mandatory retirement ages. Additionally, negative assumptions about younger workers also exist, some of which harm young workers in the workplace. All forms of ageism have negative effects on the workplace, such as disrupting morale, being dismissive of the experiences and value that older workers contribute, and in return set precedence for other forms of discrimination. Ageism can impact everyone in the workplace. Although the passage of anti-discrimination legislation has curtailed some of the more obvious forms of discrimination, the psychological underpinnings behind age- discriminatory behavior still exist and must be mitigated to ensure a fair playing field for all people. In this study, the researcher examined ways a worker can be discriminated against based on assumptions about age and explores ways discriminatory behavior can be mitigated. Furthermore, the full extent to which anti-discrimination legislation has provided a positive, and occasionally negative impact is also discussed. Discrimination never truly goes away; it only changes form. When the psychological motivators behind discrimination are not properly addressed, managers themselves might harbor discriminatory assumptions about their workers. A quantitative method was employed to identify factors and determine the best ways to combat factors that contribute to age discrimination. The findings indicated that some forms of ageism can be combatted by using certain forms of cognitive conditioning and self-assessment for hiring managers. All of the participants were hiring managers who took part in cognitive exercises designed to gain information about their opinions, but also induce a self-reflective means of evaluating their own prejudices. The evidence indicated that some factors, such as gender, do not play as large of a role as previously assumed, but that the age of the manager does play a small role in age discrimination in hiring. It was concluded that ageism does still exist, but that these assumptions can be countered effectively, which implies that better sensitivity and managerial training could be beneficial for hiring managers.</p><p>

Reconsolidation theory states that stabilized memories can be reactivated and altered in some way; the memory must then be made stable once again by a process known as reconsolidation. A substantial number of studies have aimed to examine this process and the conditions under which it can occur in animal models and young adults. However, few studies have examined the impact of aging on memory reconsolidation. It has been established that aging affects episodic memories, as a result of several different changes in aging. Further, associative, source, and context memories have been found to be affected by aging. Additionally, consolidation, the process that occurs prior to reconsolidation, has been linked to age-related memory deficits. Given these changes with age, it is possible that memory reconsolidation could also be affected. This dissertation sought to examine the effects of aging on reconsolidation in an established set-learning paradigm typically utilized in young adults to demonstrate reconsolidation-mediated memory updating. In Experiment 1, older adult participants were taught sets of objects on two different days, with one group receiving a reminder intended to reactivate the first day's memory. On a third day, a recognition memory task was given. We found that reconsolidation processes seem relatively intact in our population of older adults. Further, source confusion was implicated in addition to memory updating as the cause of memory errors in the group that received the reminder. Other measures, such as spatial awareness and sleep, were utilized to help explain the outcome of the experiment. In Experiment 2, young adults performed the same procedure as in Experiment 1 to determine the role of some of the aspects of the procedure in this paradigm. Specifically, we wanted to establish whether an added task, spread across the two days of learning, influenced the outcome of this paradigm. It was concluded that this task likely had an influence, such that even the group that did not receive the reminder showed evidence of memory updating. We also wanted to determine a baseline for the spatial awareness task used in the previous experiment. However, results were inconclusive. In Experiment 3, we investigated the time line of errors made by older adults by testing their memory for the first set of objects shortly after they learned the second set, as opposed to on a third day. However, free recall was used as the memory task, unlike the previous two experiments. Unexpectedly, errors were immediately apparent for the group that did not receive the reminder but not for the group that did. The conclusion of this experiment was that the task used to test memory may play a major role in the outcome of this paradigm when performed by older adults. Further testing will need to be performed to fully understand this result. Overall, memory reconsolidation appears to be intact in older adults, though perhaps not in the form seen in young adults. Reconsolidation seen in older adults could be affected by different modes of reactivation, sleep, and methods of memory testing. However, several of the present results could be open to multiple interpretations, which require future research to untangle.

Ce travail de thèse est consacré à l’étude du vieillissement UV d’un caoutchouc EPDM (éthylène propylène diène monomère) avec une attention spéciale sur les additifs du système de vulcanisation. Pour cela nous avons utilisé des techniques particulièrement adaptées à l’analyse de surface telles que le ToF-SIMS, l’XPS, l’ATR-FTIR, le MEB-EDX et l’AFM. Dans un premier temps nous avons pu déterminer la composition chimique de la surface du caoutchouc EPDM vulcanisé à l’état initial. Nous avons pu identifier les sous-produits de vulcanisation et déterminer de manière qualitative leur répartition en surface. Les profils en profondeur ToF-SIMS ont permis de mettre en évidence une couche d’enrichissement en additifs à le surface du caoutchouc dont l’origine pourrait provenir de leur migration par cristallisation ou « effet bloom » par vulcanisation. Dans la seconde partie, nous avons étudié l’effet du vieillissement artificiel SEPAP sur le caoutchouc et sur les additifs. Nos résultats montrent que la surface du caoutchouc ainsi que les deux accélérateurs de vulcanisation, le MBTS (2,2’-Dithiobis(benzothiazole)) et le ZBPT (Zinc O, O-Dibutylphosphorodithioate) subissent des changements chimiques et morphologiques profonds caractérisés par une oxydation chimique et une dégradation structurale. Les études cinétiques ont montré que les changements chimiques les plus importants étaient observés pendant les 100 premières heures. Nous avons examiné un caoutchouc industriel, actuellement utilisé dans l’étanchéité de carrosserie, afin de mieux comprendre le comportement des agents de mise en oeuvre à l’état initial et au cours du vieillissement. Ces agents de mise en oeuvre jouent un rôle clé dans la composition chimique du caoutchouc à l’état initial malgré la faible quantité incorporée. Nous avons montré que ces composés recouvrent la surface et forment une couche épaisse d’environ 500 nm, très résistante au vieillissement. / This thesis is devoted to the study of UV aging of an EPDM rubber with particular emphasis on additives involved invulcanization. For this purpose, we use techniques suitable for surface analysis such as ToF-SIMS, XPS, ATR-FTIR, SEMEDXand AFM. We first determine the initial chemical composition of the surface of the EPDM rubber. We identify the by-products of vulcanization and qualitatively determine their distribution on the surface. The ToF-SIMS depth profiles exhibit a layer enriched in additives on the surface of the rubber due to migration by crystallization or by the “bloom effect” after vulcanization. In addition, images from 3D profiles show that some of these additives are adsorbed on the no-black fillers. In the second part, we study the effect of artificial aging on the rubber and the additives. Our results indicate that both the surface of the rubber and the two rubber accelerators, MBT and ZBPT, undergoes significant chemical and morphological changes characterized by chemical oxidation and structural degradation. Our Kinetic studies show that the most important chemical changes take place during the first 100h. The final chapter is devoted to the study of industrial rubber, currently used in vehicle body seals, and discusses on understanding of the behavior of the processing agents in the initial state and during aging. These agents play a key role in the chemical composition of the rubber in the initial state, despite the small amounts incorporated. We show that these compounds cover the surface and form a layer about 500 nm thick, very resistant to aging.

Previous fMRI studies have demonstrated that older adults who perform as well as young adults on certain cognitive tasks recruit additional brain regions relative to younger adults while performing these tasks. This phenomenon has been interpreted as a compensatory response and may reflect an effort to maintain performance in the face of increasing changes in cognitive difficulty or age-related brain changes in structure and/or function. Whether the compensatory response is specific to older adults or represents a more general response of any individual to increasing task difficulty is unclear. The present fMRI experiment explored age differences in brain activity associated with increases in task difficulty in two tasks, an episodic-retrieval task that is expected to be difficult for older compared to young adults, and a lexical-semantic task that is expected to be more difficult for young compared to older adults. In the lexical-semantic task, participants judged whether pairs of words were synonyms or antonyms. In the episodic task that followed, participants made yes/no memory judgments for the word pairs previously presented. Difficulty was manipulated using word frequency -low frequency words are more difficult in the lexical-semantic judgment task and easier in the episodic task. Young (ages 18-24) and older healthy adults (ages 60-83) were scanned on a 3T GE magnet using a single-shot spiral pulse sequence. Behavioral results showed a double dissociation – older adults were adversely affected by word frequency in the episodic but not the semantic task, while young adults were adversely affected by word frequency in the semantic but not the episodic task. Both groups showed activation in similar task-related and task-general regions regardless of difficulty level). Age-related differences were observed for task-specific and linear increases due to difficulty. Linear increases in fMRI activation were associated with younger adults showing increased task difficulty in bilateral task-related regions during the lexical semantic task, whereas in the episodic retrieval task only activating bilateral posterior cortices. As difficulty increased, older adults showed unilateral brain activations: left regions for the lexical-semantic task and medial and right hemisphere regions for the episodic retrieval task. Most importantly, difficulty load increases paralleled the groups' behavioral results: younger adults showed greater increases in activity in the lexical-semantic task compared to older adults, but not in the episodic retrieval task, whereas older adults showed the opposite pattern, with greater increases in activation only in the episodic task when compared to younger adults. Thus, younger and older adults recruit regions differently in response to increases in difficulty. Our results suggest that increases in fMRI activation as difficulty increases occur as an interaction to deal with task difficulty and the inherent abilities of the individuals, rather than occurring only in older adults, or in older adults across all tasks, regardless of their abilities in that domain.

[pt] O objetivo da presente tese é a modelagem matemática e a simulação gráfica do processo de envelhecimento facial humano. Para modelar este processo foram realizadas as seguintes etapas: estudo dos principais aspectos envolvidos no envelhecimento facial, observação do efeitos visíveis do envelhecimento sobre a face, definição das principais regiões faciais relacionadas com o processo de envelhecimento, medição das variações destas regiões ao longo do tempo em um grupo de pessoas, elaboração de um modelo de envelhecimento comum a todo o grupo e criação de curvas de envelhecimento facial. A partir destas curvas características, utilizando-se técnicas de Processamento de Imagens, foi elaborado um programa de simulação gráfica do envelhecimento facial (Warping de Envelhecimento Facial). Um vez que a quantificação do envelhecimento foi obtida, tornou-se, deste modo, possível visualizá-lo com base científica. A modelagem de um fenômeno biológico e mecânico que ocorre com todos, contribui com as diversas áreas envolvidas no campo da Bio-Engenharia. Conhecendo-se o processo de envelhecimento torna-se possível: propor novas técnicas para retardar ou atenuar tais efeitos, servir de base para pesquisas que permitem avaliar os esforços mecânicos que a pele é submetida ao longo do tempo, apoiar a decisão sobre a idade ideal de intervenção cirúrgica e possivelmente auxiliar no reconhecimento de pessoas que encontram-se por muito tempo desaparecidas. / [en] This thesis describes a mathermatical model and graphical simulation for human being facial ageing phenomenon. The modelling procedure was defined as follows: study about the main characteristics of the facial ageing, the definition and measurement of the main affected áreas by the ageing; the generation of na ageing pattern based on the variation of the measured areas and the definition of ageing curves. The graphical simulation was based on the use of image processing techniques. A graphical software was developed using waríng procedures which promotes on facial images based on the mentioned ageing curves. Once the ageing phenomenon was mathematically modelled it is possible its scientific visualization. The main applications of the implemented software are in the Bioengineering área. The proposed model na help the understandig of the ageing which can be used in the development of new techniques to control its effects. The software also can be used as a decision support system in surgical área allowing the proposition of the ideal age for plastic surgery. Besides these scientific applications, social one is the assistance in the edentification of disappeared people.

<p> Semantic network breakdown has been posited to be related to the progressive declines observed in Alzheimer&rsquo;s disease (AD) and its prodromes. While the relationship between semantic memory and AD has been established, the relationship between semantic memory and instrumental activities of daily living (IADL) is less clear. The current study was designed to elucidate this relationship by examining a semantic clustering index on the California Verbal Learning Test, Second Edition (CVLT-II) and the measure&rsquo;s ability to predict functional compromise of healthy older participants and those with Alzheimer&rsquo;s disease or Mild Cognitive Impairment (MCI) on two measures of IADLs&mdash;the Everyday Cognition Scale (ECog) and the Functional Activities Questionnaire (FAQ). The results revealed that semantic clustering performance differentiated between AD, amnestic MCI, and normal control participants. The FAQ distinguished between AD and non-AD participants, while the ECog differentiated between AD, amnestic MCI, and normal controls. When considering all diagnostic groups, semantic clustering was predictive of instrumental ADL functioning as measured by the ECog and FAQ, but the addition of an executive functioning covariate (Trails B) significantly improved the predictive models. In excluding the AD group from the analysis, semantic clustering was predictive of instrumental ADL functioning as measured by the FAQ beyond that of Trails B. In excluding the AD group, semantic clustering was not predictive of instrumental ADL functioning as measured by the ECog.</p><p>

Abstract not available.

The current thesis examined local and whole-body heat loss responses during heat stress at rest, exercise and/or pharmacological stimuli as a function of increasing age. The first study examined the effects of age on whole-body heat loss and heat storage during passive exposure to conditions representative of the upper temperature extremes in Canada. The results demonstrate that the cumulative change in body heat content after 2 h of rest was significantly greater in older adults in a hot-dry (older: 212±25; young: 131±27 kJ, P=0.018) and hot-humid (older: 426±37; young: 317±45 kJ, P=0.037) condition. The second study evaluated the maximal capacity of whole-body evaporative heat loss as a function of age and aerobic fitness. The findings demonstrate that whole-body evaporative heat loss was significantly lower in middle-aged untrained (Ex2: 426±34; Ex3:497±17 W) and older (Ex2: 424±38; Ex3: 485±44 W) compared to young (Ex2: 472±42; Ex3: 558±51 W) and middle-aged trained (Ex2: 474±21; Ex3: 552±23 W) males at the end of the last two exercise bouts (P<0.05). The third study assessed the maximal capacity of whole-body evaporative heat loss in females and found that whole-body evaporative heat loss was significantly lower (P=0.002) in the older (Ex2: 343±39 W; Ex3: 389±29 W) compared to the young (Ex2: 383±34 W; Ex3: 437±36 W) females at the end of the second and third exercise-induced heat loads of 325 and 400 W, while no differences were observed during recovery (P=0.693). The fourth study examined nitric oxide-dependent sweating during exercise/rest cycles in young and older adults. We showed that nitric oxide-dependent sweating during short bouts of exercise in the heat is observed in young males, but not in older adults. The fifth study examined: 1) the extent to which peripheral factors (i.e., sweat gland and skin vasodilatory function) contribute to the postexercise suppression of heat loss; and 2) whether age-related differences exist in the mechanisms modulating postexercise heat loss. The findings demonstrate that there were no differences in sweat rate between the no exercise resting condition and a postexercise condition at either an acetylcholine (ACh) or methacholine (MCh) site for the young (ACh: P=0.992 and MCh: P=0.710) or older (ACh: P=0.775 and MCh: P=0.738) adults. However, older adults had a lower sweating response for both the no exercise resting condition (ACh: P=0.049 and MCh: P=0.006) and postexercise condition (ACh: P=0.050 and MCh: P=0.029) compared to their younger counterparts. Taken together, the current thesis shows true age-related impairments in the ability to dissipate heat exist during both a passive and exercise-induced heat stress over a certain heat load threshold. Specifically, older adults have an impaired ability to dissipate heat compared to young adults during rest in hot-dry and hot-humid conditions. Additionally, middle-aged untrained and older adults have a reduced capacity to dissipate heat at an exercise-induced heat load of ≥400 W for males and ≥325 W for females, which becomes more pronounced at as the level of heat load increases. However, the age-related impairment in heat loss can be attenuated by maintaining a high level of aerobic fitness. Furthermore, age-related impairments in sweating may be associated with age-related reductions in nitric oxide-mediated sweating. However, there does not appear to be age-related differences in the modulation of heat loss postexercise.

The purpose of this thesis was to review research on the developmental physiological processes of aging which have significance for adult learning. Attention was directed, specifically, to the progressive, age-related changes most immediately associated with the skills of communication: vision, audition, speech, reaction and movement times to visual and auditory stimuli, perception, retention, and performance facility. Affective reaction to physiological aging was also considered. In recognition of the interdisciplinary nature of the relationship of aging to learning, research from diverse areas was examined. Psychological inferences, in some instances, predominate since the study is concerned not with aging but with learning concomitant with the aging processes. References of recent date were normally consulted. Investigations have revealed no "typical adult" nor even a typical or an average progression in any aspect of physiological development; therefore, an individualized response to any adult learning situation can be expected. The evidence with the greatest impact for the education of adults lies in the areas of previous learning, recency of learning, and habits of learning. There are educational needs not now met by adult education; not the least of these is the need for understanding the processes involved in physiological aging. It is well categorized that older people can learn and under certain conditions do learn, but adults being different learners require a different social, educational, and physical environment in which to learn. The facilities at present provided for child-youth education and "adapted" for adults present some frustrating physical limitations for adult learners. Adults have distinctive needs for learning. Where these needs have been catered to, the measure of success has been high, the failure rate low. There is an awareness of the fallacy of setting arbitrary limits to successful achievement based solely on chronological divisions. / Education, Faculty of / Educational Studies (EDST), Department of / Graduate

The purpose of this study was to examine the phenomenon of aging at the cellular level in vitro. Some of the biological mechanisms underlying the aging process, which may invoke a change at the level of the DNA were studied. Morphological changes were analysed with phase-contrast microscopy and functional changes by the use of tritiated thymidine in combination with autoradiography as well as by cell treatment with colchicine. A method is described for obtaining "aged" or "old" cells in vitro. In the human cells (human embryonic kidney) as well as the rat, mouse, and Syrian hamster cells, morphological changes in vitro are basically the same as aging progresses. These include transformation to a polygonal, epithelial -1ike shape; binucleation; an accumulation of "age pigments" around the nucleus; the appearance of ragged edges of the cell membrane; an increase in the overall cell size; and a loss of a regular (often parallel) orientation to adjacent cells. The mitotic rate and DNA-synthesizing capacity in "young" and "aged" cells were examined using autoradiography and cell treatment with colchicine. Evidence is presented that DNA-synthesizing aged cells are non-proliferating while DNA-synthesizing young cells are mitotically active. The significance of DNA-synthesis in non-dividing "aged" cells is discussed. The number of population doublings (generation times or cell divisions) that it takes hamster and mouse cells to age in vitro was also investigated. Thirteen and six cell generation times were found to cause hamster and mouse cells to age with a loss of proliferative capacity. The effect of various molarities of 4-nitroquinoline-1 oxide (4-NQO), on DNA of aged cells, which results in an unscheduled DNA-repair synthesis, was studied using autoradiography. It appears that an aged cell responds to these concentrations in much the same way as young cells; however, there does seem to be a slightly greater sensitivity to toxic doses of 4-NQO in aged cells. Autoradiographic studies also revealed that the duration of DNA-repair is the same in both aged and young cells, but the former appear to have a decreased capacity to repair damage to the DNA of the pretreated cells caused by the 4-NQO. The significance of this apparent decrease in the DNA-repair capacity of "aged" cells is discussed. Mouse cells, aged in vitro, were exposed to human adenovirus type 12 (strain Huie). Evidence is presented that this external agent stimulated these aged cells to increase DNA-synthesis and also pushed them into mitosis (for at least one cell division). The possibility that this might be an accountable mechanism for the observation of an accumulation of mutations in aged cells is evaluated. Aged cells were examined for frequencies and types of chromosome aberrations after exposure to adenovirus type 12. Among the most common are chromatid breaks and double fragments. As well, old cells exhibited a much higher frequency of chromosome aberrations than young cells after viral exposure. A comparison of this in vitro system of cell aging with an in vivo system is presented. The application of all of the aforementioned results and observations concerning the cellular aging process to the problem of carcinogenesis and neoplasia is emphasized. / Science, Faculty of / Zoology, Department of / Graduate