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Scaling temperature dependence of disease dynamics from individuals to populations
No full textThere is growing interest among ecologists to develop mechanistic models that can generate generalizable predictions across multiple levels of biological organization. A key question is whether and how host and parasite contributions to infection can be disentangled, and to what degree these separate contributions affect population level transmission dynamics. The Metabolic Theory of Ecology (MT) provides a framework to investigate physiological processes such as metabolism, reproductive rates, host defenses, and parasite infectivity. The amphibian fungal pathogen <Batrachochytrium dendrobatidis (Bd) is a popular host-parasite system to experimentally investigate temperature dependent infection dynamics. In Chapter 2, I validated methods for decontaminating nitrile and cotton gloves after handling Bd infected Xenopus laevis. In Chapter 3, I conducted two Bd infection experiments to quantify temperature-dependent infection on individual X. laevis and found persistent acclimation effects and increased infection loads on frogs following a drop in temperature, consistent with the Temperature Variability Hypothesis (TVH). In Chapter 4, I quantified MT-based thermal performance curves (TPC) to estimate a key metabolic parameter (activation energy, EA) for 60 amphibian species, allowing me to investigate taxonomic and environmental predictors of species specific EA. Temperate species had wider thermal breadths than tropical species and EA was positively correlated with mean environmental temperature within order Caudata, consistent with the Climate Variability Hypothesis (CVH). To test whether MT-based thermal mismatch models can successfully describe individual infections, I built and parameterized models using independent proxies for host and parasite metabolic performance. These models successfully captured the individual infection dynamics observed in Chapter 3 and provided new insights into the thermal biology of this infection. To investigate population-level transmission dynamics, I conducted a controlled temperature outdoor mesocosm Bd transmission experiment with small populations of X. laevis and tracked infections via weekly skin swabs (Chapter 6). Frog populations at 10 C had dramatically higher infection loads compared to individually housed frogs at the same temperature. In Chapter 7, I developed and fully parameterized an Individual Based Model (IBM) that nested individual level MT-based mismatch models within population level transmission dynamics, successfully predicting the higher infection loads and mortality rates observed in the population level experiment
Why should i tell you? Differences in self-disclosure among sexual minorities are associated with experiences with minority stress
No full textMinority stress has been identified as a significant contributor to mental/physical health disparities within sexual minority populations. The Minority Stress Model describes different sources of stress, such as distal (e.g., victimization) and proximal stressors (e.g., internalized stigma), alongside ameliorating processes, such as social support, that can influence health outcomes. The stressors that an individual might experience are partially influenced by sexual orientation, with some identities experiencing stressors that are specific to that sexual identity. One avenue through which minority stress might impact health outcomes is through disclosure of a minority identity, an experience that is often associated with positive health outcomes but may invite stigma. Across three sets of analyses, gay/lesbian, bi+, and asexual participants reported experiences with minority stress, past experiences with disclosure, and willingness to disclose their identity as a sexual minority in two hypothetical contexts. The first research question examined differences in coming out milestones, finding that asexual participants reported discovering, identifying with, and disclosing their sexual minority identity at later ages over shorter intervals than gay/lesbian and bi+ samples. The second research question demonstrated indirect effects of the associations between discrimination events and microaggressions and likelihood to disclose through the proximal stressors expectations of rejection and internalized stigma, although these associations differed by sexual orientation. The third research question demonstrated that community connectedness moderated the association between expectations of rejection and likelihood to disclose orientation, but only for the asexual sample. Across these analyses, different orientations reported consistent differences in the minority stressors that were associated with disclosure, which could help clinicians customize treatments to better address their minority clients’ needs
Does the possibility of no surgery in watch and wait for rectal cancer affect patient decision-making?
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