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D Quigley

Publications and source records attributed to D Quigley.

10 recordsLinked to original sources
PubMed2005

Progression of phase behavior for a sequence of model core-softened potentials.

A series of phase diagrams is obtained in three dimensions for a smooth pair potential with an outer well and a repulsive inner shoulder. Condensed phase boundaries are located using free energy calculations. Liquid-vapor equilibria are obtained with multicanonical methods. As the depth of the outer well is increased, a simple-hexagonal to close-packed transition appears in the solid, leading to a discontinuity in the slope of the melting curve. For deeper wells the simple hexagonal melting temperature exhibits a maximum with respect to pressure. The onset of the predicted metastable isostructural transition is also studied.

Journal Article↗
PubMed2005

Phase behavior of a three-dimensional core-softened model system.

The phase behavior of a three-dimensional model substance interacting via a continuous core-softened pair potential is studied. A combination of thermodynamic integration and free-energy augmented metadynamics is employed to identify the ground state structure as simple hexagonal. A transition to close packing is predicted at high pressure. The melting line is traced, which when combined with the liquid-vapor line, allows the liquid to be studied over its entire thermodynamically stable range. We find no liquid anomalies in the range of pressures for which the vaporization transition exists. Our results therefore support suggestions that the anomalous behavior of such fluids is unique to the two-dimensional case.

Journal Article↗
PubMed2004

Langevin dynamics in constant pressure extended systems.

The advantages of performing Langevin dynamics in extended systems are discussed. A simple Langevin dynamics scheme for producing the canonical ensemble is reviewed, and is then extended to the Hoover ensemble. We show that the resulting equations of motion generate the isobaric-isothermal ensemble. The Parrinello-Rahman ensemble is then discussed and we show that despite the presence of intrinsic probability gradients in this system, a Langevin dynamics approach samples the extended phase space in the correct fashion. The implementation of these methods in the ab initio plane wave density functional theory code CASTEP [M. D. Segall, P. L. D. Lindan, M. J. Probert, C. J. Pickard, P. J. Hasnip, S. J. Clarke, and M. C. Payne, J. Phys.: Condens. Matter 14, 2717 (2003)] is demonstrated.

Journal Article↗
PubMed2004

Marijuana use and epilepsy: prevalence in patients of a tertiary care epilepsy center.

The authors sought to determine the prevalence of marijuana use in patients with epilepsy by performing a telephone survey in a tertiary care epilepsy center. Twenty-one percent of subjects had used marijuana in the past year with the majority of active users reporting beneficial effects on seizures. Twenty-four percent of all subjects believed marijuana was an effective therapy for epilepsy. Despite limited evidence of efficacy, many patients with epilepsy believe marijuana is an effective therapy for epilepsy and are actively using it.

Adult↗
PubMed2000

The assessment of radiation exposures in Native American communities from nuclear weapons testing in Nevada.

Native Americans residing in a broad region downwind from the Nevada Test Site during the 1950s and 1960s received significant radiation exposures from nuclear weapons testing. Because of differences in diet, activities, and housing, their radiation exposures are only very imperfectly represented in the Department of Energy dose reconstructions. There are important missing pathways, including exposures to radioactive iodine from eating small game. The dose reconstruction model assumptions about cattle feeding practices across a year are unlikely to apply to the native communities as are other model assumptions about diet. Thus exposures from drinking milk and eating vegetables have not yet been properly estimated for these communities. Through consultations with members of the affected communities, these deficiencies could be corrected and the dose reconstruction extended to Native Americans. An illustration of the feasibility of extending the dose reconstruction is provided by a sample calculation to estimate radiation exposures to the thyroid from eating radio-iodine-contaminated rabbit thyroids after the Sedan test. The illustration is continued with a discussion of how the calculation results may be used to make estimates for other tests and other locations.

Adolescent↗
PubMed1996

On the origin of lateral asymmetry.

Lateral asymmetry refers to unequal fluorescent intensity between adjacent regions of sister chromatids. It has been observed in the centromeric regions of mitotic chromosomes of mouse or human origin when cells are grown in 5-bromo-2'-deoxyuridine (BrdU) for a single round of DNA synthesis. The chromosome-orientation fluorescence in situ hybridization (CO-FISH) technique was used with pseudodiploid mouse cells to show that the regions of asymmetrical brightness coincide with major satellite repetitive DNA, and that the more heavily BrdU-substituted chromatid is the one that fluoresces less brightly. These observations support a 20 year old hypothesis on the origin of lateral asymmetry. Other observations suggest that differential loss of DNA from the heavily substituted chromatid also contributes to lateral asymmetry.

Animals↗
PubMedDate not supplied

Participatory research strategies in nuclear risk management for native communities.

The Nuclear Risk Management for Native Communities (NRMNC) project is a collaborative academic, community-based, tribal project, which conducts the three essential elements of participatory research: research, education, and community action, named here as "community-based hazards management." This article describes the goals and outcomes of this effort in assisting Native American communities in Nevada, Utah, and Southern California affected by nuclear fallout from U.S. weapons testing in the 1950s and 1960s. The NRMNC project sought to create new models for dealing with health research and risk communication needs in an environmental justice setting. The following results of this four-year project are discussed: (1) building a community-based environmental health infrastructure, (2) building community capacities through workshops and educational materials, (3) conducting both technical and community research, and (4) facilitating community-based hazards management planning. We describe such positive outcomes as the improvements in the scientific database through participatory research activities, the development of equitable relationships between scientists and community members, and the creation of a sustaining program intervention for long-term community needs. The project's outcomes are presented as an expansion to limited scientific risk management outcomes in the environmental health field that often are solely quantitative and lack relevance to community concerns about environmental health impacts from contamination.

California↗
PubMedDate not supplied

Reducing the incidence of ventilator-related pneumonia.

Ventilator-related pneumonia is costly not only in terms of treatment, equipment, and length of stay but also in terms of patient morbidity and mortality. From October 1995 through March 1996 an increase in ventilator-related pneumonia cases, of which 83% were caused by methicillin-resistant Staphylococcus aureus (MRSA), was noted at a Veterans Affairs medical center. A multidisciplinary team based on the TQI model and using TQI tools, methodology, and principles of problem solving was subsequently formed to look into ventilator-related pneumonia. The team's data collection and analysis efforts identified numerous opportunities for improvement. The primary outcome has been a decrease in the incidence of ventilator-related pneumonia that has resulted in substantial cost savings.

Benchmarking↗