Minority Stress: A Model for Understanding Sexual Minority Adolescents’ Mental Health

Taken together, the three papers included in this dissertation offer an investigation of sexual minority adolescents’ stress as a predictor of adverse mental health outcomes (Paper 1), as being influenced by school and home climates (Paper 2), and as a measurable model for stress across levels (Paper 3). Results from this series of studies generally support theory and findings from other studies in that minority stress was found to be a meaningful predictor of mental health in sexual minority youth and that school and home climates were found to be important for understanding sexual minority youth wellbeing. However, the current set of papers went beyond confirming past research and offered new contributions to the literature by identifying differences in the levels at which minority stress’ predicts mental health (Paper 1), showing how school and home climates both influence sexual minority youths’ wellbeing and that school climates offer a better explanation for the wellbeing of sexual minority adolescents (Paper 2), and providing support for the measurement of minority stress for adolescents. Findings from this series of studies may help support the knowledge and measurement necessary for informing mental health providers’ practice to reduce mental health disparities in sexual minority youth

The Moderating Role of Psychological Inflexibility in the Relationship Between Minority Stress, Substance Misuse, and Suicidality in LGB+ Adolescents

Adolescence is a difficult time, especially for those who do not identify as heterosexual (e.g., gay, lesbian, bisexual, asexual, pansexual; LGB+). Increased rates of substance abuse and suicidality are well documented outcomes that tend to be worse in the LGB+ adolescent community than in mainstream groups. Minority stress, the effect of unique stressors experienced by those in the LGB+ community explained by external and societal influences, has been accepted within the research community as a theory used to explain the health disparities seen in this group. This study proposed a possible further explanation, in addition to minority stress, that helps clarify the relationship between minority stress and negative outcomes, and that is changeable through Acceptance and Commitment Therapy (ACT). Psychological inflexibility, a rigid reaction to life events that is inconsistent with values and often promotes avoidant behavior, and five of its six key sub-processes (experiential avoidance, cognitive fusion, lack of values, preoccupation with the past or future, and inaction) was posited as influencing the strength of the relationship between minority stress and substance misuse or suicidality. Interactions with both global psychological inflexibility and its sub-processes were examined using statistical models to explore relationships between minority stress and both suicidality and substance misuse in the LGB+ adolescent community. A sample of 152 LGB+ adolescents participated. Significant interactions were found in models of substance misuse but not suicidality, with global psychological inflexibility, cognitive fusion, and obstruction of valued living as moderators that strengthened the relationship between minority stress and substance misuse. Implications based on results suggest that psychological inflexibility as a mechanism of change in LGB+ adolescents is worth further study. Additional examination into the effectiveness of ACT in LGB+ populations struggling with minority stress’ effects and/or substance misuse should be conducted to advance the understanding of these results

Properties of cage rearrangements observed near the colloidal glass transition

We use confocal microscopy to study the motions of particles in concentrated colloidal systems. Near the glass transition, diffusive motion is inhibited, as particles spend time trapped in transient ``cages'' formed by neighboring particles. We measure the cage sizes and lifetimes, which respectively shrink and grow as the glass transition approaches. Cage rearrangements are more prevalent in regions with lower local concentrations and higher disorder. Neighboring rearranging particles typically move in parallel directions, although a nontrivial fraction move in anti-parallel directions, usually from pairs of particles with initial separations corresponding to the local maxima and minima of the pair correlation function $g(r)$, respectively.Comment: 5 pages, 4 figures; text & figures revised in v

Local molecular field theory for the treatment of electrostatics

We examine in detail the theoretical underpinnings of previous successful applications of local molecular field (LMF) theory to charged systems. LMF theory generally accounts for the averaged effects of long-ranged components of the intermolecular interactions by using an effective or restructured external field. The derivation starts from the exact Yvon-Born-Green hierarchy and shows that the approximation can be very accurate when the interactions averaged over are slowly varying at characteristic nearest-neighbor distances. Application of LMF theory to Coulomb interactions alone allows for great simplifications of the governing equations. LMF theory then reduces to a single equation for a restructured electrostatic potential that satisfies Poisson's equation defined with a smoothed charge density. Because of this charge smoothing by a Gaussian of width sigma, this equation may be solved more simply than the detailed simulation geometry might suggest. Proper choice of the smoothing length sigma plays a major role in ensuring the accuracy of this approximation. We examine the results of a basic confinement of water between corrugated wall and justify the simple LMF equation used in a previous publication. We further generalize these results to confinements that include fixed charges in order to demonstrate the broader impact of charge smoothing by sigma. The slowly-varying part of the restructured electrostatic potential will be more symmetric than the local details of confinements.Comment: To be published in J Phys-Cond Matt; small misprint corrected in Eq. (12) in V

Vacuum Energy Density for Massless Scalar Fields in Flat Homogeneous Spacetime Manifolds with Nontrivial Topology

Although the observed universe appears to be geometrically flat, it could have one of 18 global topologies. A constant-time slice of the spacetime manifold could be a torus, Mobius strip, Klein bottle, or others. This global topology of the universe imposes boundary conditions on quantum fields and affects the vacuum energy density via Casimir effect. In a spacetime with such a nontrivial topology, the vacuum energy density is shifted from its value in a simply-connected spacetime. In this paper, the vacuum expectation value of the stress-energy tensor for a massless scalar field is calculated in all 17 multiply-connected, flat and homogeneous spacetimes with different global topologies. It is found that the vacuum energy density is lowered relative to the Minkowski vacuum level in all spacetimes and that the stress-energy tensor becomes position-dependent in spacetimes that involve reflections and rotations.Comment: 25 pages, 11 figure

Reconstructing the global topology of the universe from the cosmic microwave background

If the universe is multiply-connected and sufficiently small, then the last scattering surface wraps around the universe and intersects itself. Each circle of intersection appears as two distinct circles on the microwave sky. The present article shows how to use the matched circles to explicitly reconstruct the global topology of space.Comment: 6 pages, 2 figures, IOP format. To be published in the proceedings of the Cleveland Cosmology and Topology Workshop 17-19 Oct 1997. Submitted to Class. Quant. Gra

Circles in the Sky: Finding Topology with the Microwave Background Radiation

If the universe is finite and smaller than the distance to the surface of last scatter, then the signature of the topology of the universe is writ large on the microwave background sky. We show that the microwave background will be identified at the intersections of the surface of last scattering as seen by different ``copies'' of the observer. Since the surface of last scattering is a two-sphere, these intersections will be circles, regardless of the background geometry or topology. We therefore propose a statistic that is sensitive to all small, locally homogeneous topologies. Here, small means that the distance to the surface of last scatter is smaller than the ``topology scale'' of the universe.Comment: 14 pages, 10 figures, IOP format. This paper is a direct descendant of gr-qc/9602039. To appear in a special proceedings issue of Class. Quant. Grav. covering the Cleveland Topology & Cosmology Worksho

Exact Polynomial Eigenmodes for Homogeneous Spherical 3-Manifolds

Observational data hints at a finite universe, with spherical manifolds such as the Poincare dodecahedral space tentatively providing the best fit. Simulating the physics of a model universe requires knowing the eigenmodes of the Laplace operator on the space. The present article provides explicit polynomial eigenmodes for all globally homogeneous 3-manifolds: the Poincare dodecahedral space S3/I*, the binary octahedral space S3/O*, the binary tetrahedral space S3/T*, the prism manifolds S3/D_m* and the lens spaces L(p,1).Comment: v3. Final published version. 27 pages, 1 figur