An analysis of the day supervisor's activities

Thesis (M.S.)--Boston Universit

Chiral Vortons and Cosmological Constraints on Particle Physics

We investigate the cosmological consequences of particle physics theories that admit stable loops of current-carrying string - vortons. In particular, we consider chiral theories where a single fermion zero mode is excited in the string core, such as those arising in supersymmetric theories with a D-term. The resulting vortons formed in such theories are expected to be more stable than their non-chiral cousins. General symmetry breaking schemes are considered in which strings formed at one symmetry breaking scale become current-carrying at a subsequent phase transition. The vorton abundance is estimated and constraints placed on the underlying particle physics theories from cosmological observations. Our constraints on the chiral theory are considerably more stringent than the previous estimates for more general theories.Comment: minor corrections made. This version will appear in PR

Examples of Embedded Defects (in Particle Physics and Condensed Matter)

We present a series of examples designed to clarify the formalism of the companion paper `Embedded Vortices'. After summarising this formalism in a prescriptive sense, we run through several examples: firstly, deriving the embedded defect spectrum for Weinberg-Salam theory, then discussing several examples designed to illustrate facets of the formalism. We then calculate the embedded defect spectrum for three physical Grand Unified Theories and conclude with a discussion of vortices formed in the superfluid $^3$He-A phase transition.Comment: final corrections. latex fil

Cosmological Consequences of Slow-Moving Bubbles in First-Order Phase Transitions

In cosmological first-order phase transitions, the progress of true-vacuum bubbles is expected to be significantly retarded by the interaction between the bubble wall and the hot plasma. We examine the evolution and collision of slow-moving true-vacuum bubbles. Our lattice simulations indicate that phase oscillations, predicted and observed in systems with a local symmetry and with a global symmetry where the bubbles move at speeds less than the speed of light, do not occur inside collisions of slow-moving local-symmetry bubbles. We observe almost instantaneous phase equilibration which would lead to a decrease in the expected initial defect density, or possibly prevent defects from forming at all. We illustrate our findings with an example of defect formation suppressed in slow-moving bubbles. Slow-moving bubble walls also prevent the formation of `extra defects', and in the presence of plasma conductivity may lead to an increase in the magnitude of any primordial magnetic field formed.Comment: 10 pages, 7 figures, replaced with typos corrected and reference added. To appear in Phys. Rev.

Evolution of Fields in a Second Order Phase Transition

We analyse the evolution of scalar and gauge fields during a second order phase transition using a Langevin equation approach. We show that topological defects formed during the phase transition are stable to thermal fluctuations. Our method allows the field evolution to be followed throughout the phase transition, for both expanding and non-expanding Universes. The results verify the Kibble mechanism for defect formation during phase transitions.Comment: 12 pages of text plus 17 diagrams available on request, DAMTP 94-8

Cosmic Vortons and Particle Physics Constraints

We investigate the cosmological consequences of particle physics theories that admit stable loops of superconducting cosmic string - {\it vortons}. General symmetry breaking schemes are considered, in which strings are formed at one energy scale and subsequently become superconducting in a secondary phase transition at what may be a considerably lower energy scale. We estimate the abundances of the ensuing vortons, and thereby derive constraints on the relevant particle physics models from cosmological observations. These constraints significantly restrict the category of admissible Grand Unified theories, but are quite compatible with recently proposed effects whereby superconducting strings may have been formed close to the electroweak phase transition.Comment: 33 pages, 2 figures, RevTe

External Stoma Diversion: A Palliative Measure for Peristomal Wound Healing in Resource-Limited Settings

The provision of intestinal stoma care is challenging in austere settings due to limitations in surgical and wound care access as well as the high cost and sparsity of ostomy supplies. As a result, many surgical patients suffer from ostomy-related complications such as peristomal wounds and are unable to find relief for these complications from standard treatments and measures. This article describes the external stoma diversion, a cost-effective palliative surgical procedure that assists in the healing of peristomal wounds in resource-limited settings

Psychological preparation and postoperative outcomes for adults undergoing surgery under general anaesthesia

Acknowledgements We wish to dedicate this work to the memory of Christian Osmer, a dedicated, caring doctor who was committed to achieving the best care for his patients and their relatives. He saw his contribution to this project as a way of advancing best care for surgical patients. We are very grateful for his valuable input to this work and the pleasure we had in working with him. We are grateful to Karen Hovhanisyan (former Trials Search Co-ordinator, Cochrane Anaesthesia, Critical and Emergency Care Group (ACE)) for carrying out the electronic database searches and to Jane Cracknell (Managing Editor, ACE) for her support throughout the review process. We would also like to thank W Alastair Chambers and Manjeet Shehmar for clinical advice relating to judgements about general anaesthesia usage, and Yvonne Cooper and Louise Pike who retrieved documents and screened papers as research assistants in earlier stages of the review. We are grateful to the following colleagues who helped us with foreign language papers - either by screening papers or by providing translation: Stefano Carrubba, Chuan Gao, Chen Ji, Kate Rhie, Reza Roudsari and Alena Vasianovich. We would like to thank Andy Smith (content editor), Nathan Pace (statistical editor), Michael Donnelly, Allan Cyna and Michael Wang (peer reviewers), and Shunjie Chua (consumer referee) for their help and editorial advice during the preparation of this systematic review. We would also like to thank Andrew Smith (content editor), Nathan Pace (statistical editor), Michael Wang and Allan Cyna (peer reviewers), and Lynda Lane (Cochrane Consumer Network representative) for their help and editorial advice during the preparation of the protocol (Powell 2010). Sources of support Internal sources Manchester Centre for Health Psychology, University of Manchester, UK. An award of £2000 was received to support research assistant costs. External sources British Academy, UK. We received a small research grant of £7480 to support research assistant costs.Peer reviewedPublisher PD

Data Collection Challenges and Recommendations for Early Career Researchers

Data collection is critical to the social research process. When implemented correctly, data collection enhances the quality of a social research study. However, doctoral students and early career researchers may encounter challenges with data collection. This article reports on the data collection challenges in dissertation research encountered by doctoral students enrolled in a public health program at a southeastern United States urban university. Each doctoral student shared at least one challenge and how it affected the data collection process. Additionally, the doctoral students shared how the identified challenges were addressed or suggested recommendations. Understanding these experiences of doctoral students is helpful for doctoral students and early career researchers conducting social research. The lessons learned may guide faculty in research mentoring and structuring research seminars for doctoral students

Recruitment in Qualitative Public Health Research: Lessons Learned During Dissertation Sample Recruitment

The purpose of this article is to describe the recruitment challenges faced by eight public health graduate students when conducting qualitative dissertation research. The authors summarize their dissertation studies, describe recruitment challenges, and provide strategies and recommendations used to address challenges. The authors identified twelve recruitment issues which they grouped into three major categories: (a) obtaining consent; (b) working with gatekeepers; and (c) accessing participants. The authors propose three recommendations to consider in participant recruitment, which are: (a) collaborate with gatekeepers; (b) use additional recruitment tools; and (c) understand your target population. The compilation of experiences from multiple graduate students from a diverse selection of topics provides valuable insight and resources when planning a qualitative research study in the field of public health