Stability Conditions and Branes at Singularities

I use Bridgeland's definition of a stability condition on a triangulated category to investigate the stability of D-branes on Calabi-Yau cones given by the canonical line bundle over a del Pezzo surface. In this context, I prove the existence of the decay of a D3-brane into a set of fractional branes. This is an important aspect of the derivation of quiver gauge theories from branes at singularities via the technique of equivalences of categories. Some important technical aspects of this equivalence are discussed. I also prove that the representations corresponding to skyscraper sheaves supported off the zero section are simple.Comment: 22 pages, uses utarticle.cls, dcpic.sty, v2: published versio

Dipoles, Twists and Noncommutative Gauge Theory

T-duality of gauge theories on a noncommutative $T^d$ can be extended to include fields with twisted boundary conditions. The resulting T-dual theories contain novel nonlocal fields. These fields represent dipoles of constant magnitude. Several unique properties of field theories on noncommutative spaces have simpler counterparts in the dipole-theories.Comment: 20pp LaTeX, amsfonts and amssymb, JHEP format and ref adde

The architectural impact of using ground-source heat pumps in commercial buildings in Las Vegas

A series of parametric studies evaluate the architectural impacts on the design and long term performance of ground-coupled heat pump systems over a fixed period of time. The results are applied to a commercial office building in order to assess the net impact of combining various energy efficiency strategies. The conclusion of the comprehensive study is that energy efficient design strongly contributes to a reduction in the required size of a ground-coupled heat pump system. A comparative life-cycle cost analysis validates these results by using the same commercial office building design to evaluate a ground-coupled heat pump system against two other commonly used HVAC systems for commercial building applications; The analysis indicates that ground-coupled heat pump systems perform competitively against other systems in terms of life-cycle costs. The impact on the ground temperature at the ground-loop in such a system rises significantly over the simulation period of 25 years. This condition strongly suggests that ground-coupled heat pump systems that do not incorporate a secondary means of heat disposal such as a cooling tower or absorption chiller may not be the most suitable HVAC system type for commercial office buildings in Las Vegas. (Abstract shortened by UMI.)

Feasibility and Acceptability of Mindfulness-Based Relapse Prevention and Adjunct Mobile Technology in Rural Communities

While problematic substance use transcends geographic regions, rural communities appear to be especially impacted. More prevalent problematic substance use and associated problems in these areas are exacerbated by lack of consistent access to evidence-based practices. Mindfulness-Based Relapse Prevention (MBRP) combines standard cognitive-behavioral relapse prevention with formal and informal mindfulness training, and may be a novel and effective treatment approach for substance use disorders (SUD) in these isolated areas. The current study explored feasibility and acceptability, and potential differences in variance accounted for by group randomization on substance use and secondary outcomes, between MBRP and treatment as usual (TAU) in a rural treatment setting, as well as the impact of a specially designed mobile application on treatment engagement and enactment. No differences were observed in variance of substance use or secondary outcome by groups; however, participants in TAU vs. MBRP were more likely to drop out of treatment against medical advice. The mobile application did not appear to impact treatment engagement or enactment. Implications and limitations are discussed

Moduli spaces for Bondal quivers

Given a sufficiently nice collection of sheaves on an algebraic variety V, Bondal explained how to build a quiver Q along with an ideal of relations in the path algebra of Q such that the derived category of representations of Q subject to these relations is equivalent to the derived category of coherent sheaves on V. We consider the case in which these sheaves are all locally free and study the moduli spaces of semistable representations of our quiver with relations for various stability conditions. We show that V can often be recovered as a connected component of such a moduli space and we describe the line bundle induced by a GIT construction of the moduli space in terms of the input data. In certain special cases, we interpret our results in the language of topological string theory.Comment: 17 pages, major revisio