A Framework for Modelling Video Content

Submitted for the degree of Doctor of Philosoph

The Role of Personality in Predicting Drug and Alcohol Use Among Sexual Minorities

Research consistently demonstrates that sexual minority status is associated with increased risk of problematic substance use. Existing literature in this area has focused on group-specific minority stress factors (e.g., victimization and internalized heterosexism). However, no known research has tested the incremental validity of personality traits as predictors of substance use beyond identified group-specific risk factors. A sample of 704 sexual minority adults was recruited nationally from lesbian, gay, bisexual, transgender, queer, and questioning community organizations and social networking Web sites and asked to complete an online survey containing measures of personality, sexual minority stress, and substance use. Hierarchical regression models were constructed to test the incremental predictive validity of five-factor model personality traits over and above known sexual minority risk factors. Consistent with hypotheses, extraversion and conscientiousness were associated with drug and alcohol use after accounting for minority stress factors, and all factors except agreeableness were associated with substance use at the bivariate level of analysis. Future research should seek to better understand the role of normal personality structures and processes conferring risk for substance use among sexual minorities

Ecological Momentary Assessment of Daily Discrimination Experiences and Nicotine, Alcohol, and Drug Use Among Sexual and Gender Minority Individuals

Objective: Sexual and gender minority (SGM) individuals experience elevated rates of minority stress, which has been linked to higher rates of nicotine and substance use. Research on this disparity to date is largely predicated on methodology that is insensitive to within day SGM-based discrimination experiences, or their relation to momentary nicotine and substance use risk. We address this knowledge gap in the current study using ecological momentary assessment (EMA). Method: Fifty SGM individuals, between 18 and 45 years of age, were recruited from an inland northwestern university, regardless of their nicotine or substance use history, and invited to participate in an EMA study. Each were prompted to provide data, six times daily (between 10:00 a.m. and 10:00 p.m.) for 14 days, regarding SGM-based discrimination, other forms of mistreatment, and nicotine, drug, and alcohol use since their last prompt. Results: Discrimination experiences that occurred since individuals’ last measurement prompt were associated with greater odds of nicotine and substance use during the same measurement window. Substance use was also more likely to occur in relation to discrimination reported two measurements prior in lagged models. Relative to other forms of mistreatment, discrimination effects were consistently larger in magnitude and became stronger throughout the day/evening. Conclusion: This study adds to existing minority stress research by highlighting the both immediate and delayed correlates of daily SGM-based discrimination experiences. These results also contribute to our understanding of daily stress processes and provide insight into ways we might mitigate these effects using real-time monitoring and intervention technology

IN A NUTSHELL: NUTRITIONAL AND ENVIRONMENTAL FACTORS IMPACTING SMALL MAMMAL SEED SELECTION IN NORTHEASTERN FORESTS

Rodents often play vital roles in their ecosystems as seed predators and dispersers and can significantly influence the succession and assembly of plant communities. We conducted seed tray experiments to assess the nutritional and environmental factors that influence selection and foraging time of three common rodent granivores: the white-footed mouse (Peromyscus leucopus), the deer mouse (Peromyscus maniculatus), and the southern red-backed vole (Myodes gapperi) for three common seeds: American beech (Fagus grandifolia), red maple (Acer rubrum), and eastern hemlock (Tsuga canadensis). This work was conducted at Bartlett Experimental Forest located within White Mountain National Forest in New Hampshire. Using mixed-effects multinomial logistic models, we identified a strong preference in all three rodent species for American beech seeds, likely due to the combination of its high energetic value and low content of harmful secondary compounds when compared to the other seed types. When beech availability was low, the white footed mouse showed a secondary preference for hemlock, the red-backed vole for red maple, and the deer mouse equal preference for both. Red maple seeds individually contain more energy than eastern hemlock seeds but also contain significantly more harmful secondary compounds. An elongated cecum may allow voles to process these compounds faster and more completely than mice, allowing them to safely forage on the red maple seeds. The resulting divergence in secondary preferences may lessen competition when beech availability is low and facilitate coexistence. Beech was not only the primary seed selected, but its availability was also the primary factor influencing foraging time. For all three rodent species, time on tray increased as beech availability decreased. The impacts of environmental factors on selection and time on tray varied by species and were only significant when beech availability was low. Effects of precipitation and stem density on selection are consistent with predator avoidance behaviors, with larger seeds more likely to be chosen in the rain and under denser shrub cover. The effects of day of year appeared significant but may have been confounded by changing levels of naturally available seeds. Precipitation and luminosity also impacted foraging time. Animals spent less time on tray in the rain, consistent with thermoregulatory behaviors. Animals also spent less time on tray on more luminous nights, consistent with predator avoidance behaviors. Our results illustrate the complexity of rodent foraging behaviors and decisions, with selections being driven by many factors. The most important of these factors is seed quality, though this can be influenced by other factors such as seed availability and environmental changes. These findings contribute to our understanding of rodent foraging patterns and underscore the importance of identifying factors influencing these patterns

Supercooled: An Equilibrium, Melting-Based, Energy Distribution Approach for Describing the Phenomenology of Metastable Liquids

The glass transition remains one of the great open problems of modern physics. This dissertation aims to increase understanding of this topic by studying the rich phenomenology of supercooled liquids, the metastable precursors to the glassy state. Principally, we aim to discover what underlying physics leads to the dramatic, non-Arrhenius increase of the viscosity and relaxation time of supercooled liquids, and what thermodynamic properties govern this physics. We propose a novel framework and associated viscosity function applicable to all supercooled liquids/glassy systems, and rigorously assess both the performance and implications of this model. We demonstrate that the theoretical framework uncovers an underlying universality in the dynamics of supercooled liquids over as much as 16 decades. We extend the model to describe the thermodynamics of supercooled liquids, as well as dynamical features outside of the viscosity/relaxation time. We conclude by discussing a micro structural link, and investigate a growing length scale associated with local rigidity, and percolating clusters of mid range order

IN A NUTSHELL: NUTRITIONAL AND ENVIRONMENTAL FACTORS IMPACTING SMALL MAMMAL SEED SELECTION IN NORTHEASTERN FORESTS

Rodents often play vital roles in their ecosystems as seed predators and dispersers and can significantly influence the succession and assembly of plant communities. We conducted seed tray experiments to assess the nutritional and environmental factors that influence selection and foraging time of three common rodent granivores: the white-footed mouse (Peromyscus leucopus), the deer mouse (Peromyscus maniculatus), and the southern red-backed vole (Myodes gapperi) for three common seeds: American beech (Fagus grandifolia), red maple (Acer rubrum), and eastern hemlock (Tsuga canadensis). This work was conducted at Bartlett Experimental Forest located within White Mountain National Forest in New Hampshire. Using mixed-effects multinomial logistic models, we identified a strong preference in all three rodent species for American beech seeds, likely due to the combination of its high energetic value and low content of harmful secondary compounds when compared to the other seed types. When beech availability was low, the white footed mouse showed a secondary preference for hemlock, the red-backed vole for red maple, and the deer mouse equal preference for both. Red maple seeds individually contain more energy than eastern hemlock seeds but also contain significantly more harmful secondary compounds. An elongated cecum may allow voles to process these compounds faster and more completely than mice, allowing them to safely forage on the red maple seeds. The resulting divergence in secondary preferences may lessen competition when beech availability is low and facilitate coexistence. Beech was not only the primary seed selected, but its availability was also the primary factor influencing foraging time. For all three rodent species, time on tray increased as beech availability decreased. The impacts of environmental factors on selection and time on tray varied by species and were only significant when beech availability was low. Effects of precipitation and stem density on selection are consistent with predator avoidance behaviors, with larger seeds more likely to be chosen in the rain and under denser shrub cover. The effects of day of year appeared significant but may have been confounded by changing levels of naturally available seeds. Precipitation and luminosity also impacted foraging time. Animals spent less time on tray in the rain, consistent with thermoregulatory behaviors. Animals also spent less time on tray on more luminous nights, consistent with predator avoidance behaviors. Our results illustrate the complexity of rodent foraging behaviors and decisions, with selections being driven by many factors. The most important of these factors is seed quality, though this can be influenced by other factors such as seed availability and environmental changes. These findings contribute to our understanding of rodent foraging patterns and underscore the importance of identifying factors influencing these patterns

A Quinean Critique of Ostrich Nominalism

Ostrich nominalists often cite Quine’s criterion of ontological commitment in order to claim that their view is more parsimonious than rival positions in ontology such as realism. We show that Quine’s criterion, properly understood, does not support this claim. Indeed, we show that ostrich nominalism has a far more profligate ontology than realism

Sexual Minority Stress and Suicide Risk: Identifying Resilience through Personality Profile Analysis

Sexual minority-based victimization, which includes threats or enacted interpersonal violence, predicts elevated suicide risk among sexual minority individuals. However, research on personality factors that contribute to resilience among sexual minority populations is lacking. Using the Five-Factor Model, we hypothesized that individuals classified as adaptive (vs. at-risk) would be at decreased risk for a suicide attempt in the context of reported lifetime victimization. Sexual minority-identified young adults between the ages of 18 and 25 years (N = 412) were recruited nationally and asked to complete an online survey containing measures of personality, sexual minority stress, and lifetime suicide attempts. A 2-stage cluster analytic method was used to empirically derive latent personality profiles and to classify respondents as adaptive (lower neuroticism and higher extroversion, agreeableness, conscientiousness, and openness) or at-risk (higher neuroticism, lower extroversion, agreeableness, conscientiousness, and openness) on the basis of their Five-Factor Personality trait scores. Adaptive individuals were slightly older and less likely to conceal their sexual orientation, but they reported similar rates of victimization, discrimination, and internalized heterosexism as their at-risk counterparts. Logistic regression results indicate that despite reporting similar rates of victimization, which was a significant predictor of lifetime suicide attempt, adaptive individuals evidenced decreased risk for attempted suicide in the context of victimization relative to at-risk individuals. These findings suggest that an adaptive personality profile may confer resilience in the face of sexual minority-based victimization. This study adds to our knowledge of sexual minority mental health and highlights new directions for future research

Evidence for the intense exchange of MazG in marine cyanophages by horizontal gene transfer

Background: S-PM2 is a phage capable of infecting strains of unicellular cyanobacteria belonging to the genus Synechococcus. S-PM2, like other myoviruses infecting marine cyanobacteria, encodes a number of bacterial-like genes. Amongst these genes is one encoding a MazG homologue that is hypothesized to be involved in the adaption of the infected host for production of progeny phage. Methodology/Principal Findings: This study focuses on establishing the occurrence of mazG homologues in other cyanophages isolated from different oceanic locations. Degenerate PCR primers were designed using the mazG gene of S-PM2. The mazG gene was found to be widely distributed and highly conserved among Synechococcus myoviruses and podoviruses from diverse oceanic provinces. Conclusions/Significance: This study provides evidence of a globally connected cyanophage gene pool, the cyanophage mazG gene having a small effective population size indicative of rapid lateral gene transfer despite being present in a substantial fraction of cyanophage. The Prochlorococcus and Synechococcus phage mazG genes do not cluster with the host mazG gene, suggesting that their primary hosts are not the source of the mazG gene