The main objective of this research was to determine the seed bank longevity of Melinis repens at two Southern Florida sites. Seeds were divided among different exposure levels (shade versus sun) and depths (surface versus buried) and tested for baseline viability using 2,3,5-Triphenyl-tetrazolium chloride. Statistical analysis determined that at the pine rockland site there was a significant interaction between time, exposure, and depth. The initial mean viability at this site declined from 49.71% to 11.26% and 13.06% for sun/buried seeds and sun/surface seeds, respectively, by month 8. The mean viability of shade/surface seeds and shade/buried seeds declined to 24.56% and 22.06% after 8 months. There were no significant effects in the Florida scrub. In order for land managers to completely remove this species from a site, treatment with herbicide will need to continue for a minimum of one year to effectively kill all viable seeds in the seed bank.

Thesis advisor: Peter Ireland / Retirees with limited financial resources face numerous risks, including out-living their money (longevity risk), investment losses (market risk), unexpected health expenses (health risk), the unforeseen needs of family members (family risk), and even retirement benefit cuts (policy risk). This study systematically values and ranks the financial impacts of these risks from both the objective and subjective perspectives and then compares them to show the gaps between retirees’ actual risks and their perceptions of the risks in a unified framework. It finds that 1) under the empirical analysis, the greatest risk is longevity risk, followed by health risk; 2) under the subjective analysis, retirees perceive market risk as the highest-ranking risk due to their exaggeration of market volatility; and 3) the longevity risk and health risk are valued less in the subjective ranking than in the objective ranking, because retirees underestimate their life spans and their health costs in late life. / Thesis (PhD) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

The United States of America is globally known as the land of opportunity, freedom, independence, equality, and above all, the American Dream. American writer and historian, James Truslow Adams, coined the phrase “American Dream” in his 1931 book The Epic of America. The American Dream is the belief that anyone, regardless of where they were born or what class they were born into, they can attain their own version of success in society through hard work, sacrifice, and taking risks. Post-World War II, the demand for home ownership rapidly increased. The development of Levittown provided single-family homes for white nuclear families, which was highly idealized by society and became a part of the American Dream. Against this backdrop, this thesis project addresses the role of architecture in adapting existing communities to serve the more comprehensive view of today’s family structures. This development concept results in a supportive and flexible environment where families of all configurations and backgrounds are accepted. In doing so, its surrounding environment will be exposed to a multi-generational and multi-cultural community, resulting in a richer and more interactive environment. Numerous co-benefits emerge from this model, including flexibility within existing and new homes, a supportive community, and synergies between different family structures.

Early exposure to hypoxia is related to a variety of physiological and metabolic changes that have lasting effects on organisms’ physiology and life history. We measured the effects of maternal and embryonic mild, intermittent hypoxia on the life history of four clones of microcrustacean Daphnia magna, an emerging model organism for the studies of senescence and longevity. Daphnia individuals were produced parthenogenically, maintained in individual vials, and fed standard algal concentration daily. The cohort consisted of 189 individuals. We measured body size at first reproduction, fecundity (including late-life fecundity peak), offspring sex ratio, and longevity. We found no effect of maternal and embryonic hypoxia on body size and longevity; however, there was a slight but statistically significant increase in age-specific mortality in the early hypoxia treatment cohort. Daphnia from the hypoxia group showed higher early fecundity which disappeared by the age of 100 days. A late-life spike in fecundity was observed at the age of 100 days when hypoxia group individuals showed significantly lower fecundity. There was little evidence of a trade-off between early- and late-life fecundity. Finally, early hypoxia affected mid-life male production in one of the four clones, and we discuss possible physiological changes triggered by maternal and embryonic exposure to hypoxia.

No description available.

The services that urban trees provide to human society and the natural environment are widely recognized, but urban trees are in jeopardy due to climate change and urban stressors. With drought as a major threat in many areas, it is important for the future of urban forestry to select species composition based upon performance under water stress. Certain leaf functional traits can help horticulturalists more accurately predict water usage of urban trees. Comprehension through rigorous experimentation is lacking, partly due to the thousands of mostly exotic species. Previous studies suggest that species whose leaves have a denser arrangement of smaller stomata and a higher leaf mass per area (LMA) are better adapted to low water availability. We sampled 70 urban tree species California and analyzed their stomatal length, stomatal density, and LMA. We compared the traits with water use data from the Water Use Classification of Landscape Species to assess possible correlations. All pairwise trait comparisons show significant correlation (P < 0.05), and LMA is significantly higher in low water use species compared to medium water use species (P= 0.0045). After using independent contrasts to incorporate phylogenetic relationships, significance was lost, implying that basal divergences are responsible for observed trends. Other potential explanations for differences in species water usage are foliar longevity (deciduous vs. evergreen) and stomatal distribution (amphistomatous vs. hypostomatous). Low water use species are more likely to be evergreen and amphistomatous compared to medium water use species. Consideration of all these traits in combination with good management practices can help ensure future success of urban forests.

Orientador: Edvaldo Aparecido Amaral da Silva / Resumo: Os oligossacarídeos da família rafinose (OFR), presentes nas sementes/grãos de soja, são açúcares solúveis considerados fatores antinutricionais para humanos e animais monogástricos, e por isso, limitam o uso da cultura para estes. Entretanto, estes compostos aparentam exercer um papel fundamental na aquisição da qualidade fisiológica das sementes de soja. Diante disso, genótipos mutantes que expressam o fenótipo de baixo ou ultrabaixo teor de OFR têm sido estudados visando à eficiência da alimentação humana e animal. Portanto, é preciso elucidar as funções dos OFR sobre as propriedades da qualidade fisiológica de sementes, a fim de preconizar materiais genéticos de alta qualidade, com capacidade de armazenamento e propagação. Todavia, a qualidade fisiológica e os teores de açúcares solúveis podem ser alterados em função da genética do genótipo ou do ambiente. Por isso, genótipos mutantes em OFR podem apresentar a aquisição da qualidade fisiológica distinta quando produzidos em diferentes ambientes. Objetivou-se com este trabalho elucidar a contribuição dos OFR na aquisição da qualidade fisiológica de sementes de soja em genótipos que expressam teores contrastantes destes. Para tal, foram utilizadas sementes com fenótipos para baixo e ultrabaixo teor de OFR, mutantes nas enzimas rafinose sintase (rs) 2 e rs2 rs3, respectivamente, em comparação a genótipos com alelos funcionais para RS2 (teores normais de OFR), produzidos em três safras. As sementes foram colhidas em diferente... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The raffinose family of oligosaccharides (OFR), present in soybean seeds/grains, are soluble sugars considered as antinutritional factors for humans and monogastric animals, and therefore, they limit the use of the crop. However, these compounds seem to play a fundamental role in the acquisition of physiological quality of soybean seeds. Thus, mutant genotypes expressing phenotype of low or ultralow content of OFR have been studied aiming at the efficiency of human and animal feeding. Therefore, it is necessary to elucidate the functions of OFR on the properties of physiological seed quality, in order to recommend materials of high-quality genetic material with storability and propagation capacity. The physiological quality and soluble sugar content may be altered in genetic or environmental function. Therefore, mutant OFR genotypes may acquire distinct physiological quality when grown in different environments. The aim of this research was to elucidate the contribution of OFR in the acquisition of the physiological quality of soybean seeds in genotypes that express contrasting contents for these in three experimental crops. For this, seeds with low and ultralow OFR phenotypes, mutants in raffinose synthase (rs) 2 and rs2 rs3, respectively, were used in comparison to genotypes with RS2 functional alleles (normal OFR levels). The seeds were harvested at different phenological stages during their maturation. Subsequently, it was evaluated for all genotypes studied in all harves... (Complete abstract click electronic access below) / Mestre

Healthspan describes the length of time an individual lives without disability or chronic disease. Characteristic to aging is the risk for the onset of both through a progressive accumulation of deficits in normal physiologic function. In the past, the declines associated with aging were simply accepted as inevitable. Today, longevity research has undergone a meteoric rise in popularity. This is due to several landmark studies demonstrating that what was once thought of as inevitable has potential to be delayed. This thesis aims to consolidate current theories of biochemical processes believed to underlie aging, and explore their interconnections. Furthermore, current pharmaceutical and lifestyle interventions being studied to promote longevity and target these specific pathways will be analyzed for safety and practicality for use in a primary care setting. Through a shift from symptom-based care to personalized preventative care, the goal is to maximize function into older age and empower individuals to live life to the fullest well beyond what was previously imagined.

Thesis advisor: Erika Sabbath / As college degrees become increasingly standard expectations for middle-to-high wage positions in the workforce, growing numbers of children and parents in the United States are accruing and repaying loans for postsecondary education. At the same time, the United States is witnessing unprecedented rates of longevity and a subsequent need for more intentional financial planning for retirement that starts earlier in life. The goal of this three-paper dissertation is to explore how student loans are experienced within families and discover the ways in which borrowers of different ages perceive and prioritize retirement and longevity-planning in light of their student loans. Utilizing qualitative and quantitative data collected through a concurrent triangulation mixed methods study design, the first two papers explored how student loan borrowers make, negotiate, and experience student loans within their family of origin. Paper 1 focused on the family context of borrowers repaying loans for their own education, and Paper 2 focused on the family context of borrowers repaying loans for a child or grandchildren education, several of whom were also repaying additional loans for their own educational expenses. Ultimately, the ways in which families communicated about student loans during repayment played at least a partial role in how they experienced the loans as part of their overall family dynamics. Shifting from a focus on family dynamics to longevity planning, Paper 3 focused on ways in which borrowers perceive and plan for longevity in light of the loans they carry for themselves and/or family members. Results suggest that planning for future financial security for oneself and/or family members may be less achievable with the presence of student loan debt. The main contribution of this dissertation is its attempt to understand the ways in which borrowers experience student loans in family systems and longevity planning contexts. This dissertation has also highlighted gaps in knowledge that policymakers, practitioners, and scholars can begin to address with current and potential student loan borrowers. / Thesis (PhD) — Boston College, 2019. / Submitted to: Boston College. Graduate School of Social Work. / Discipline: Social Work.

Obesity and obesity related diseases represent a leading cause of mortality in the United States and worldwide. Our research is oriented towards the role of lipid metabolism in longevity. Adipose triglyceride lipase, or ATGL, is a rate limiting enzyme in the lipolytic pathway. The nematode, C. elegans has many conserved biologic pathways to mammals, and the lipolytic pathway is one of them. The homologues include the insulin receptor (DAF-2), FoxO1 (DAF-16), and ATGL (ATGL-1). In this study, we use C. elegans as a model to study the role of lipolysis in longevity. It has been previously shown in our lab that overexpression of ATGL-1::GFP increases lifespan. To confirm that the increase in longevity was due to the overexpression of ATGL-1, we have used RNA interference to downregulate expression of ATGL-1::GFP. We have corroborated that ATGL-1::GFP worms have longer lifespans, than wildtype N2 worms. We have also found that RNAi control diet does not affect lifespan of ATGL-1::GFP strains. However, ATGL-1::GFP strains on an RNAi GFP diet demonstrate reduced levels of ATGL-1::GFP and have shorter lifespans compared to their control counterparts. Our findings confirm that overexpression of ATGL-1 increases lifespan of C. elegans probably due to its role in reducing fat content.