Ageing is a progressive impairment of function causing decreased defense against environmental challenges and increased risk of many diseases. The development of ageing and ageing-related diseases might be attenuated by nutrients such as carotenoids and polyunsaturated fatty acids. In the present study, for the first time, two nutrient-rich marine microalgae, namely Haematococcus pluvialis (HP) and Schizochytrium mangrovei (SM) were studied for their anti-ageing effects both in vitro and in vivo. Results of nutritional profile analysis confirmed that HP is rich in astaxanthin (AX) (978.9 μg/g). Using rat adrenal medulla pheochromocytoma (PC12) cells as an in vitro model, AX exhibited significant protective effects against oxidative stress induced by H2O2 or amyloid β-peptide (Aβ). To testify whether AX conveys such effects to HP, the anti-ageing property of HP was subsequently investigated on Drosophila melanogaster. In the group of SODn108 mutant fruit flies, lifespan elongation effect was observed, where HP may play as a complement of the defective endogenous antioxidant system to extend the lifespan and ameliorate the age-related decline of locomotor function. On the other hand, a long-term intake of HP (20 mg/mL) induced early mortality of wild type fruit flies, which was associated with the decreased enzymatic activities of CuZn-superoxide dismutase (SOD1) and Mn-superoxide dismutase (SOD2) as well as mRNA down-regulation of SOD1, SOD2, and Catalase (CAT). Further study showed that HP supplementation contributed to the defense of wild type OR fruit flies against chronic but not intensive oxidative stress. The observed ‘bifacial effect’ could be resulted from ‘hormesis’ responses, suggesting the therapeutic instead of the preventive potential of HP against ageing-related diseases. Another microalga SM was found to contain abundant docosahexaenoic acid (DHA) (53 mg/g). The in vitro studies showed that SM failed to protect PC12 cells under H2O2-induced oxidative stress due to its poor anti-oxidative activity. However, from in vivo studies, the SM supplementation significantly extended the lifespan of both wild type and SODn108 mutant fruit flies and ameliorated the age-related decline of locomotor function. Further studies revealed that the observed activities were associated with the mRNA up-regulation of endogenous stress-defending genes such as SOD1 and SOD2, as well as the down-regulation of methuselah (MTH) gene. It has been proposed that antioxidants may protect DHA against oxidative damage. To determine whether there is a synergistic effect for HP and SM, a mixture of these two algal samples was evaluated for its effects on the lifespan of D. melanogaster. Results showed that the wild type fruit flies fed with the mixture had no elevated survival rate, tentatively suggesting that the increased nutritional complexity may trigger elevated metabolic rate and lead to shortened lifespan. In conclusion, results of the present study demonstrated the anti-ageing properties of nutrient-rich microalgae both in vitro and in vivo, suggesting SM possesses the potential to be used as a preventive diet supplementation, while HP may be a suitable candidate as therapeutic agents. Based on these findings, the health benefits of nutrient-rich microalgae for the elderly as well as patients with ageing-related diseases were proposed. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / Pharmacology and Pharmacy / Doctoral / Doctor of Philosophy

Age identity has long been considered a more meaningful and accurate reflection of the aging process than chronological age. However, it is still a mostly unexplored concept among Chinese older adults. What are the correlates of age identity from the perspective of a multidimensional, culturally-shared model of aging? How do Chinese older adults describe their age identities, and are there any recent related trends? Does the adaptive value of youthful age identity in later life, which promotes well-being and successful aging, also exist in the Chinese context? Six studies using quantitative methods were devised to answer the above questions. Data were drawn from the three waves of the Sample Survey on Aged Population in Urban/Rural China (SSAPUR), with Study I using data from the 2006 SSAPUR, Study II using data from the 2000, 2006, and 2010 SSAPURs, and Studies III-VI using 4-year-panel data from the 2006 and 2010 SSAPURs. Study I examined correlates of age identity among Chinese older adults (N = 18,925). The findings reveal that multidimensional age markers, including chronological age, number of chronic conditions, widowhood, loss of both parents, and perceived onset of forgetfulness were all positively associated with age identity. Among these, perceived onset of forgetfulness was the strongest predictor. Study II investigated how Chinese older adults describe their age identities, and whether or not there have been any trends over the most recent decade (N = 20,166 in 2000; N = 19,922 in 2006; N = 19,874 in 2010). The findings reveal that old age is perceived to start at around the chronological age of 60 years, but that women are perceived as becoming old four years earlier than men. The findings also indicate that a majority of Chinese older adults reported feeling old. Nevertheless, there has been a general upward trend for increasingly higher percentages of them to report not feeling old over the recent years. Study III determined the effect of age identity on subjective well-being among Chinese older adults (N = 11,306). The findings indicate that a baseline youthful age identity is associated with better subjective well-being. Study IV investigated the impact of age identity on physical functioning among Chinese older adults (N = 11,366), and its findings indicate that a baseline youthful age identity is related to better physical functioning. Study V examined the impact of age identity on productive engagement, including paid work and volunteering among Chinese older adults (N = 11,473). The findings indicate that relative to abaselineold age identity, a baseline youthful age identity is associated with higher odds of productive engagement. On the basis of Studies III-V, Study VI explored the impact of age identity on a multidimensional conceptualization of successful aging among Chinese older adults (N = 10,070), and its findings indicate that a baseline youthful age identity is associated with higher odds of successful aging. The practical and theoretical implications of the present research are discussed in this thesis, along with its limitations and recommendations for future research. / published_or_final_version / Social Work and Social Administration / Doctoral / Doctor of Philosophy

Soil aging refers to the increase in strength and stiffness that is exhibited over time after it is disturbed. It is common in granular soils, such as sands, occurring over periods from hours to years. There have been relatively numerous laboratory studies on sand aging phenomena. However the majority of these studies were conducted on relatively clean sand (fines content <5%) and were performed under isotropic condition. In nature, granular soils with fines content > 5% are not uncommon. This research is an attempt to gain further insight and understanding of mechanical aging on silty sand by conducting laboratory studies mostly under K0 condition, which better reflects the field condition, at both macro-scale (triaxial test) and micro-scale (fabric test). As many factors (e.g. plasticity of fines, fines content, grain size composition, angularity and shape) affect silty sand behaviour and not all those factors could be investigated during the study period, this study focused on mechanical aging of non-plastic silty sand with 15% fines content. Triaxial tests have been conducted in this study in order to observe creep behavior under different density, initial fabric, and consolidation stress paths (K0 and isotropic). The tests were conducted at low effective confining stress stresses i.e. ’3= 30 – 120 kPa as this is relevant to many geotechnical aging problems (e.g. time effects on freshly deposited or disturbed soils such as in the case of hydraulic fills, mine tailings, and post-liquefaction state of soil behaviour following earthquakes). Creep induced aging effects on undrained shear behaviour at small-strain (<0.1% of shear strain), were investigated, as this strain range is most common in geotechnical structures under gravity-induced working loads. Aging effects on one way cyclic behaviour were also studied. Some new key findings from these tests are as follows: (1) Creep following K0 consolidation indicated that the soil tends to expand radially over time, resulting in a tendency of increasing horizontal stress with time even at low stress. (2) Following K0 consolidation, density appears to have more significant effect on creep compared to initial shear stress ratio and mean effective stress; as demonstrated by loose samples (low stress ratio and mean effectives stress) which exhibited greater creep compared to those of dense sample (higher stress ratio and mean effective stress) (3) For loose soils, there is a trade-off between high confining stresses driving aging and collapsing pore space. Generally higher confining stress was found to increase creep tendency thus enhancing aging, however there was also found to be a certain confining pressure where the aging effects became less due to local structure collapse. (4) Initial fabric plays an important role on creep development, thus aging. For instance, dense dry pluviated samples developed larger axial strain over time but also gained less increase in stiffness compared to dense moist tamped samples. This suggests the importance of specimen preparation for laboratory testing that replicates the field scenarios e.g. natural deposition and associated fabric; (5) Dense K0 consolidated samples produce more increase in stiffness with time than corresponding isotropically consolidated samples. Hence, as the K0 condition generally reflects the level-ground free field stress condition better, it is important to test under K0 if the degree of stiffness gain is important; (6) The number of cycles to trigger cyclic softening and liquefaction for one way cyclic loading increases with the aging duration. In addition there is tendency that the aging effect is more pronounced at lower cyclic stress ratios. Fabric tests under K0 consolidation with similar variables as the triaxial tests were also performed. Some new insights and contributions have been obtained as follows: (1) Moist tamped samples, have particles that are more clustered together and structured than dry pluviated samples; (2) In terms of particle orientation, a change in the degree of orientation for both sand particles and ‘fines’ under constant loading was observed with time. The dominant (i.e. most) rotated particles (sand or “fines’) depends on the initial fabric and density; (3) Over time, under constant loading, growth of micro voids was observed for dense samples while those of loose samples contracted; (4) A new parameter, variance to mean void ratio of void distance, was introduced as a measure of the degree of interlocking during aging. The variance to mean ratio of void distance for moist tamped samples tends to decrease whereas those of dry pluviated samples tends to increase with time. An increase in variance and variance to mean ratio for dry pluviated samples indicates that particles are more clustered together with time; (5) Original work on spatial void distance for the numerical analysis of creep induced aging based on Kang et al. (2012) was conducted (note: the model’s boundary condition allows lateral expansion, which is not the same as the fabric tests conducted). The analysis showed that mean void size in dense soil tends to increase with time under constant load while for loose sample it tends to decrease. However the particles also clustered together more – increasing structure. (6) A microstructural study of “undisturbed samples”, obtained by gel-push sampling, of clean sand (fines content = 4%) and silty sand (fines content = 30%), was conducted to investigate anisotropy of natural fabric of granular soils. The results show that dry pluviation reflects the field condition more, in terms of natural deposition, than moist tamping. In addition, spatial void distance qualitatively indicated the undisturbed samples are relatively “very young”, even in terms of engineering time, as indicated by similar variance to mean ratio and kurtosis with those of 1 hour and 1 week reconstituted samples. This research has shown that there was a relation between changes in the microstructure over time and changes in macro mechanical properties of non-plastic silty sand. Further improvement in theoretical modeling (e.g. numerical modeling of creep on polydisperse granular material) and experimental aspects (e.g. examining different grain size composition and angularity, different fines content, the influence of the shape of sand and fines and use of the photo-elastic method) will allow a better understanding of the sand aging phenomenon in silty sand.

Graduate

published_or_final_version / abstract / Ecology and Biodiversity / Master / Master of Philosophy

<p> In the United States, the number of people in the over 65 year category will rise to 80 million, or 20% of the total population by 2040 (Palmore, 2009). This older group traditionally requires more services ranging from healthcare to housing than younger generations. Skilled nursing facilities provide long-term care for older adults who need around the clock nursing support, and are likewise increasing in number to accommodate this change. </p><p> One of the challenges facing retirement communities is respecting residents&rsquo; rights of autonomy and control while still following the many required laws and regulations placed on skilled nursing establishments (Frank, 2002). Administrators often desire to create a home-like environment, but the setting may still interfere with residents&rsquo; ability to make personal choices, which is an essential component associated with empowerment in the home (Frank, 2002). Given the value of stories in revealing hopes, dreams and perceptions, some researchers suggest that narrative inquiry is a valuable technique for gathering data in studies of the elderly. There is an advantage of older adults presenting their views on life: researchers can gain a better grasp of the needs of any individual by accessing his or her personal accounts of the aging experience (Harrigan &amp; Raiser, 1998). </p><p> This study explored the built environment&rsquo;s role in perceived empowerment by skilled nursing residents. Literature suggests that a sense of control, choice, and autonomy are factors that can determine if an older resident is satisfied with their living conditions that, in turn, may facilitate empowerment and overall well-being. This concept is the foundation for the study&rsquo;s primary research question: What role do empowering elements in the built environment play in supporting quality of life for skilled nursing residents? The Person-Environment (P-E) Fit Theory by Kahana, Lovegreen, Kahana, &amp; Kahana shaped the study&rsquo;s approach (2003), which evaluates the interaction of personal preferences and environmental characteristics along the following four physical and two social domains: Physical Amenities/Aesthetics, Resource Amenities, Safety, Stimulation/Peacefulness, Homogeneity/Heterogeneity, and Interaction/Solitude. As the name suggests, the goal is to have a positive &ldquo;fit&rdquo; of the preferences and characteristics that leads to resident satisfaction and psychological well-being (Kahana et al., 2003). </p><p> The research study was comprised of two phases. The first phase involved interviewing skilled nursing residents which allowed them to share stories with the researcher of their lived experience in their long-term care facilities. They were asked about their perceptions of the spaces in the facilities that the residents determined to be empowering. The second phase took the form of observation mapping in which the researcher tracked the movement and activities of the general population of residents in the common areas of the study&rsquo;s two site facilities. </p><p> Through the residents&rsquo; stories and site observations, this study reviewed a range of residents&rsquo; lived experiences from roommate relations to favorite pastimes to quiet moments. The P-E Fit theory domains proved a helpful model to understand certain physical aspects of empowerment in skilled nursing facilities. However, those domains were not able to fully explain some of the psychosocial concepts that residents expressed, which they perceived to be beneficial. The researcher discovered emerging themes for empowerment that combined both the physical findings as supported by the P-E Fit domains and these additional psychosocial findings that included personal relationships, sense of belonging, sense of identity, and knowledge of community culture. The emerging themes lead to the development of ten guidelines for skilled nursing facilities that identify and recommend empowering elements in the built environment. These included resident room equals home; centralized place to access resources, freedom to access community spaces, centralized social gathering spaces, places for retreat, connection to nature, off-campus adventures, places to explore personal interests, sense of belonging, and safety. The intent is that these guidelines will benefit skilled nursing facility administrators, staff, and other design professionals who seek to empower and improve quality of life for older adults.</p>

Purpose: The purpose of this study was to explore the experience of individuals who are aging with a lifelong and/or early-onset physical impairment. Method: A qualitative methodology was utilized consisting of narrative inquiry informed by the Life Course Perspective. The life course perspective is a dynamic approach that encompasses multiple theories including sociology, human development, and aging, highlighting how social, historical, and cultural contexts shape people’s lives. Narratives are storied ways of knowing and communicating that people use to organize events in their lives and make sense out of their experiences. Nine community-dwelling individuals (3 men; 6 women), aged 26-70, with mild to severe Cerebral Palsy were recruited using a combination of purposive and snowball sampling. Multiple (3-4), in-depth interviews were completed with each participant in order to co-construct their life stories. The data analysis was iterative. NVIVO 8 was used to organize the data, supporting a systematic caparison of emerging themes and categories, as well as the central plot that weaves the participants’ experiences together. Findings: “Defying the Odds” emerged as the central narrative that weaved together their experience of growing up and growing older. Their narrative is depicted through the trajectory of the disordered body that manifests itself in peaks and valleys. Their narrative is also weaved together by three central threads: Achieving a Sense of Belonging, Overcoming being Seen but not Heard, and Striving for Self-Reliance. “Normalization” emerged as a key recurring theme in the participants’ life stories. The focus of rehabilitation on "normalizing" movement, particularly walking, during childhood can lead to social psychological challenges as well as problems later in the life course as people encounter increasing fatigue and decreasing functional abilities but no longer have access to rehabilitation services. Implications: Theoretically, the disordered body needs to be reconceptualized in ways that are more positive. Conceptualizing a theory on aging with disability needs to be pursued. Clinically, we need to work towards developing a continuum of care across the life course with a focus on long-term maintenance and prevention of secondary health problems.

To date, research on cognitive aging has treated attention as a unitary resource that operates according to a single mechanism of top-down selection. However, contemporary theoretical models of attention propose that it is a distributed resource, embedded in distinct cortical subsystems, and operates in a manner that reflects the properties of those subsystems. For instance, perceptual attention is thought to originate in posterior sensory subsystems and filter competing unattended input prior to encoding, resulting in early selection of attended information. Executive attention, by contrast, is thought to originate in frontal control subsystems and filter unattended input after encoding, resulting in late selection of attended information. Guided by a distributed resource model, the work described here focuses on how healthy advanced aging influences early selection mechanisms embedded in posterior subsystems, perceptual encoding, and the relationship with frontal subsystems mediating late selection. To examine perceptual attention in isolation, object discrimination tasks were devised in which perceptual competition between repeated objects was manipulated while holding demand on executive control constant. Cortical mechanisms of early selection were probed using functional magnetic resonance imaging (fMRI) indices of neural response and adaptation. Evidence of an age-related impairment in early selection was detected across two fMRI experiments. Unlike young adults, unattended objects not only interfered with perceptual encoding in older adults, but were co-encoded along with the contents of attended input. Age impairments in early selection were also associated with greater reliance on frontally-mediated late selection resources, and, reduced functional connectivity with basal forebrain nuclei. In sum, the results indicate that with increasing age, frontal control subsystems become increasingly encumbered with compensatory redistribution of function from the perceptual cortices, possibly due to loss of central cholinergic integrity. Many well-described age-related deficits of executive attention may therefore represent a consequence of impaired early selection, rather than its cause.

This study investigated the influence of training on interference in younger and older adults using the Eriksen flanker task. Does flanker interference differ with age and, as practice progresses, does the pattern of interference change? Younger and older adults were given five sessions of training on the flanker task over five successive days. On each trial, participants saw a central target letter flanked vertically by two flanker letters; the flankers could be either compatible or incompatible with the target. Participants were to respond to the identity of the central letter, ignoring the flanker letters. Although older adults were slower overall than younger adults in responding, the two groups showed virtually identical overall benefits from practice. Critically, the two age groups showed equivalent and constant interference due to incompatible flankers at all stages of practice. In the flanker paradigm, aging slows response execution without affecting attention within a trial or learning across trials.