Valued occupational roles and life satisfaction among south Florida HIV-infected and non-infected homosexual males: An exploratory study

A study was conducted in order to describe and understand the occupational role behavior of gay men with particular interest on understanding the impact of an HIV diagnosis on their roles and life satisfaction. A 137-item questionnaire was developed for this study and distributed through various gay community groups in south Florida. The process resulted in ranked description of 24 valued occupational roles of gay men (n = 80) along with a general understanding of potential shifts that may occur in those roles as a result of becoming infected with HIV. The study concludes that a diagnosis of HIV infection impacts gay men both by altering their value for particular roles and by darkening the images they hold of their future. The study also identified key factors which may contribute to the greater life satisfaction of gay men including greater confidence in personal knowledge of HIV, a more optimistic outlook an life, the use of stronger coping styles, and perceiving stronger social support and lower stress. ^

Ecological correlates of successful colonization in the life history of the Cuban treefrog, {\it Osteopilus septentrionalis\/} (Anura: Hylidae)

Ten correlates of successful colonization were tested and met in the life history of the Cuban treefrog in Florida and the Caribbean. Like many successful colonizing species of animals, the Cuban treefrog was highly fecund; reproduction was possible at a small body size in males (27.0 mm) and females (45.0 mm), and large females could lay large clutches and eggs throughout the year. Generation times were short in this species thereby accelerating the colonization process. Tadpoles and post-metamorphic individuals could exploit a wide range of physical conditions with respect to weather conditions and structure of the habitat. The Cuban treefrog occupied the terrestrial-arboreal niche which was only marginally exploited by other species in Florida. Habitat preference of the Cuban treefrog was for mesophytic forests and disturbed areas, and both habitats were found in native and introduced ranges. The ability to coexist with man further enabled the Cuban treefrog to expand its geographic range. A broad diet enabled the Cuban treefrog to exploit a wide range of prey species and sizes thereby alleviating an important constraint to colonization success. The Cuban treefrog was gregarious and vagile, thereby accelerating the process of dispersal which is crucial to the colonization process. Thus, many features in its life history enabled the Cuban treefrog to rapidly disperse and colonize, often in high population densities, many kinds of sites in its native and introduced range. Conformity to these correlates by the Cuban treefrog ultimately provides predictive power regarding the future colonization of this tropical frog. ^

Cultural differences in possible selves during later life

This study explored the ways in which culture may influence the future self-representations of older adults. Cultural differences are explained within the theoretical paradigm of individualism vs. collectivism. The sample consisted of 100 older adults, comprised of 50 Spanish-speaking natives and 50 English-speaking natives. Their ages ranged from 60 to over 90 years. Participants were given interviews consisting of demographic information and The Possible Selves Inventory. Results indicate that the possible selves of native English-speakers were more reflective of characteristics of an individualistic culture, and the possible selves of native Spanish-speakers reflect the characteristics of a collectivistic culture. The findings of this study serve to bridge a gap in the literature on the influence culture has on the possible selves older adults envision. ^

Dynamic Behavior and Fatigue Life of Highway Bridges Due to Doubling Heavy Vehicles

An increase in the demand for the freight shipping in the United States has been predicted for the near future and Longer Combination Vehicles (LCVs), which can carry more loads in each trip, seem like a good solution for the problem. Currently, utilizing LCVs is not permitted in most states of the US and little research has been conducted on the effects of these heavy vehicles on the roads and bridges. In this research, efforts are made to study these effects by comparing the dynamic and fatigue effects of LCVs with more common trucks. Ten Steel and prestressed concrete bridges with span lengths ranging from 30’ to 140’ are designed and modeled using the grid system in MATLAB. Additionally, three more real bridges including two single span simply supported steel bridges and a three span continuous steel bridge are modeled using the same MATLAB code. The equations of motion of three LCVs as well as eight other trucks are derived and these vehicles are subjected to different road surface conditions and bumps on the roads and the designed and real bridges. By forming the bridge equations of motion using the mass, stiffness and damping matrices and considering the interaction between the truck and the bridge, the differential equations are solved using the ODE solver in MATLAB and the results of the forces in tires as well as the deflections and moments in the bridge members are obtained. The results of this study show that for most of the bridges, LCVs result in the smallest values of Dynamic Amplification Factor (DAF) whereas the Single Unit Trucks cause the highest values of DAF when traveling on the bridges. Also in most cases, the values of DAF are observed to be smaller than the 33% threshold suggested by the design code. Additionally, fatigue analysis of the bridges in this study confirms that by replacing the current truck traffic with higher capacity LCVs, in most cases, the remaining fatigue life of the bridge is only slightly decreased which means that taking advantage of these larger vehicles can be a viable option for decision makers.

Factors Affecting Current and Future Treeline Locations and Dynamics in the Peruvian Andes

The elevational distributions of tropical treelines are thought to be determined by temperature, and are predicted to shift upslope in response to global warming. In contrast to this hypothesis, global-scale studies have shown that only half of all studied treelines are shifting upslope. Understanding how treelines will respond to climate change has important implications for global biodiversity, especially in the tropics, because tropical treelines generally represent the upper-elevation distribution limit of the hyper-diverse cloudforest ecosystem. In Chapter 1, I introduce the idea that grasslands found above tropical treelines may represent a potential grass ceiling which forest species cannot cross or invade. I use an extensive literature review to outline potential mechanisms which may be acting to stabilize treeline and prevent forest expansion into high-elevation grasslands. In Chapters 2-4, I begin to explore these potential mechanisms through the use of observational and experimental methods. In Chapter 2, I show that there are significant numbers of seedlings occurring just outside of the treeline in the open grasslands and that seed rain is unlikely to limit seedling recruitment above treeline. I also show that microclimates outside of the closed-canopy cloudforest are highly variable and that mean temperatures are likely a poor explanation of tropical treeline elevations. In Chapter 3, I show that juvenile trees maintain freezing resistances similar to adults, but nighttime radiative cooling near the ground in the open grassland results in lower cold temperatures relative to the free atmosphere, exposing seedlings of some species growing above treeline to lethal frost events. In Chapter 4, I use a large-scale seedling transplant experiment to test the effects of mean temperature, absolute low temperature and shade on transplanted seedling survival. I find that increasing mean temperature negatively affects seedling survival of two treeline species while benefiting another. In addition, low temperature extremes and the presence of shade also appear to be important factors affecting seedling survival above tropical treelines. This work demonstrates that mean temperature is a poor predictor of tropical treelines and that temperature extremes, especially low temperatures, and non-climatic variables should be included in predictions of current and future tropical treeline dynamics.