Browsing by Subject "vulnerability"
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Item Agricultural Livelihoods and Climate Change: Employing the Livelihood Vulnerability Index in Bluefields, Jamaica(2014-08-20) Fath, KevinThe purpose of this quantitative study was to examine agricultural livelihood vulnerability to climate change in Bluefields, Westmoreland, Jamaica based on the Livelihoods Vulnerability Index (LVI). Additionally, this study sought to examine relationships between selected characteristics of adopter innovativeness and farmer vulnerability level. Random sampling was used to select participants (N=52). Personal interviews were conducted with farmers using an instrument consisting of LVI components representing livelihood strategies, natural and physical assets, socio-demographic profile, social networks, water issues, food issues, and natural disasters and climate variability. The instrument also contained questions related to selected characteristics of adopter innovativeness: years of farming experience, relative income, farm size, access to credit, contact with extension services, distance to market, and head of household age. LVI data were aggregated using an indexing approach to create scores for comparison across vulnerability components. The study showed farmers in Bluefields have the greatest amount of vulnerability in the area of social networks and water issues. Low numbers of farmers owned their land, had contact with extension services, or used irrigation. Most farmers reported having problems with access to seeds and planting material, depended on their farms for food, and experienced frequent crop failure. Only one adopter innovativeness characteristic was significantly correlated to farmer vulnerability scores. A moderate negative association was observed between perceived relative income and farmer vulnerability. Farmers in Bluefields are vulnerable to climate change. Development organizations and local change agents should target the areas of greatest vulnerability illuminated by this study. Vulnerability and its contributing factors (exposure, sensitivity, and adaptive capacity) should be reassessed with the LVI and other methods to monitor changes in Bluefields over time.Item Individual sensitivity to novelty and (+)-3,4-methylenedioxymethamphetamine: Roles for serotonin and GABA neurotransmission(2005-01-27) Julie Danielle Ross; Kathryn A. Cunningham; Thomas A. Kent; Terry E. Robinson; Mary L. Thomas; Cheryl S. WatsonDrug addiction continues to be a problem in our society, and better understanding of the neuroanatomical and neurochemical alterations that delineate the switch between causal drug use and compulsive drug addiction is needed. Characterizing what makes one individual more vulnerable to the development of compulsive drug-taking behaviors may hold the key to this complex phenomenon. Because individual differences in humans exist to the subjective effects of 3,4-methylenedioxymethamphetamine (MDMA) and these differences are rooted, in part, in individual sensitivity to the drug effects, we utilized two animal models of increased sensitivity in the current studies. First, in a sensitization animal model we examined the mechanisms of increased sensitivity to (+)-MDMA and found a critical role for serotonin (5-HT) neurotransmission, in particular the 5-HT2A receptor (5-HT2AR) in the nucleus accumbens (NAc) and prefrontal cortex (PFC). We then carried this finding into a model of individual difference in which animals are separated based on their differential locomotor response to a novel environment into high responder rats (HR) and low responder rats (LR). In addition to an increased sensitivity to (+)-MDMA, we uncovered basal differences in the 5-HT system between HR and LR rats, an increased level of expression of the 5-HT2AR in the NAc of HR rats in particular. Additionally, we examined the brain structures activated secondary to novelty in HR vs. LR rats and the phenotype-specific behavioral changes after repeated exposure to the environment. Our findings revealed a strong influence of GABA neurotransmission that may underlie the differences between HR vs. LR behavioral phenotypes. These findings lend support to the idea that the neural systems underlying drug-induced and stress-induced behaviors overlap and may help to understand how individual sensitivity to both (+)-MDMA and novelty may confer an increased vulnerability to the development of compulsive drug-taking behavior.Item Seismic fragility and retrofitting for a reinforced concrete flat-slab structure(Texas A&M University, 2004-09-30) Bai, Jong-WhaThe effectiveness of seismic retrofitting applied to enhance seismic performance was assessed for a five-story reinforced concrete (RC) flat-slab building structure in the central United States. In addition to this, an assessment of seismic fragility that relates the probability of exceeding a performance level to the earthquake intensity was conducted. The response of the structure was predicted using nonlinear static and dynamic analyses with synthetic ground motion records for the central U.S. region. In addition, two analytical approaches for nonlinear response analysis were compared. FEMA 356 (ASCE 2000) criteria were used to evaluate the seismic performance of the case study building. Two approaches of FEMA 356 were used for seismic evaluation: global-level and member-level using three performance levels (Immediate Occupancy, Life Safety and Collapse Prevention). In addition to these limit states, punching shear drift limits were also considered to establish an upper bound drift capacity limit for collapse prevention. Based on the seismic evaluation results, three possible retrofit techniques were applied to improve the seismic performance of the structure, including addition of shear walls, addition of RC column jackets, and confinement of the column plastic hinge zones using externally bonded steel plates. Finally, fragility relationships were developed for the existing and retrofitted structure using several performance levels. Fragility curves for the retrofitted structure were compared with those for the unretrofitted structure. For various performance levels to assess the fragility curves, FEMA global drift limits were compared with the drift limits based on the FEMA member-level criteria. In addition to this, performance levels which were based on additional quantitative limits were also considered and compared with FEMA drift limits.