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Search Results: 1 - 10 of 17277 matches for " Andrew Worster "
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Transforma??es da terra: para uma perspectiva agroecológica na história
Worster, Donald;
Ambiente & Sociedade , 2003, DOI: 10.1590/S1414-753X2003000200003
Abstract: this article discusses the formation of the field of environmental history which originated in the 1970s in the middle of the debates on the ecologic crisis and the emergence of the environmental movement. this history rejects the notion that human societies do not cause significant environmental alterations and analyzes the specific conditions of that recurring interaction. the agroecologic system is one of the most typical cases of the intervention of human activity on natural ecosystems in a complex interaction between indigenous plants, exotic vegetation, fertility of the soil and diverse agricultural practices. the roadmap of these changes is essential to understand history from the view point of the environment.
Transforma es da terra: para uma perspectiva agroecológica na história
Worster Donald
Ambiente & Sociedade , 2003,
Abstract: O artigo discute a constitui o do campo da história ambiental, que se deu nos anos 70 em meio aos debates sobre a crise ecológica e a eclos o do movimento ambientalista. Esta história n o aceita a no o de que as sociedades humanas n o produzem altera es ambientais significativas, e interpela as condi es específicas dessa intera o recorrente. O sistema agroecológico representa um dos casos mais típicos de rearranjo da atividade humana sobre os ecossistemas naturais, em uma rela o complexa de intera o entre plantas nativas, vegeta o forasteira, fertilidade dos solos e diversas práticas agrícolas. O itinerário dessas mudan as é essencial para se compreender a história do ponto de vista ambiental
Reviewer agreement trends from four years of electronic submissions of conference abstract
Brian H Rowe, Trevor L Strome, Carol Spooner, Sandra Blitz, Eric Grafstein, Andrew Worster
BMC Medical Research Methodology , 2006, DOI: 10.1186/1471-2288-6-14
Abstract: All abstracts were submitted using an on-line system and assessed by three volunteer CAEP reviewers blinded to the abstracts' source. Reviewers used an on-line form specific for each type of study design to score abstracts based on nine criteria, each contributing from two to six points toward the total (maximum 24). The final score was determined to be the mean of the three reviewers' scores using Intraclass Correlation Coefficient (ICC).495 Abstracts were received electronically during the four-year period, 2001 – 2004, increasing from 94 abstracts in 2001 to 165 in 2004. The mean score for submitted abstracts over the four years was 14.4 (95% CI: 14.1–14.6). While there was no significant difference between mean total scores over the four years (p = 0.23), the ICC increased from fair (0.36; 95% CI: 0.24–0.49) to moderate (0.59; 95% CI: 0.50–0.68). Reviewers agreed less on individual criteria than on the total score in general, and less on subjective than objective criteria.The correlation between reviewers' total scores suggests general recognition of "high quality" and "low quality" abstracts. Criteria based on the presence/absence of objective methodological parameters (i.e., blinding in a controlled clinical trial) resulted in higher inter-rater agreement than the more subjective and opinion-based criteria. In future abstract competitions, defining criteria more objectively so that reviewers can base their responses on empirical evidence may lead to increased consistency of scoring and, presumably, increased fairness to submitters.There is a large body of valuable and high-quality research that is, for whatever reason, never published in full manuscript format[1,2]. In fact, a published abstract is often the only permanent "official" source of information on a research project[3]. Abstracts presented at the meetings of specialty and generalist societies are now recognized as an important component of the grey literature searched in many systematic approaches t
Emergency department length of stay for patients requiring mechanical ventilation: a prospective observational study
Louise Rose, Sara Gray, Karen Burns, Clare Atzema, Alex Kiss, Andrew Worster, Damon C. Scales, Gordon Rubenfeld, Jacques Lee
Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine , 2012, DOI: 10.1186/1757-7241-20-30
Abstract: Prospective observational study of ED LOS for all patients receiving mechanical ventilation at four metropolitan EDs in Toronto, Canada over two six-month periods in 2009 and 2010.We identified 618 mechanically ventilated patients which represented 0.5% (95% CI 0.4%–0.5%) of all ED visits. Of these, 484 (78.3%) received invasive ventilation, 118 (19.1%) received NIV; 16 received both during the ED stay. Median Kaplan-Meier estimated duration of ED stay for all patients was 6.4?h (IQR 2.8–14.6). Patients with trauma diagnoses had a shorter median (IQR) LOS, 2.5?h (1.3–5.1), compared to ventilated patients with non-trauma diagnoses, 8.5?h (3.3–14.0) (p <0.001). Patients requiring NIV had a longer ED stay (16.6?h, 8.2–27.9) compared to those receiving invasive ventilation exclusively (4.6?h, 2.2–11.1) and patients receiving both (15.4?h, 6.4–32.6) (p <0.001). Longer ED LOS was associated with ED site and lower priority triage scores. Shorter ED LOS was associated with intubation at another ED prior to transfer.While patients requiring mechanical ventilation represent a small proportion of overall ED visits these critically ill patients frequently experienced prolonged ED stay especially those treated with NIV, assigned lower priority triage scores at ED presentation, and non-trauma patients.
Tampering by office-based methadone maintenance patients with methadone take home privileges: a pilot study
Michael Varenbut, David Teplin, Jeff Daiter, Barak Raz, Andrew Worster, Pasha Emadi-Konjin, Nathan Frank, Alan Konyer, Iris Greenwald, Melissa Snider-Adler
Harm Reduction Journal , 2007, DOI: 10.1186/1477-7517-4-15
Abstract: When properly prescribed and used, methadone is an effective and safe medication in the treatment of opioid dependence and chronic pain. Prescribed methadone in adequate doses reduces cravings, prevents the onset of withdrawal, is not intoxicating or sedating, and its use does not interfere with normal activities of daily living [1,2]. In addition, methadone maintenance treatment significantly lowers illicit opioid drug use, reduces crime, and enhances social productivity [3].The regulation of methadone varies across the world, with tighter controls in the USA, Canada and Australia [4]. In the Province of Ontario, supervised dosing is an essential component of MMT, and under certain circumstances, the prescribing physician may authorize methadone doses to be consumed by the patient without supervision, that is, by way of take home doses. Such circumstances include when patients demonstrate clinical stability, namely, the social, cognitive and emotional stability necessary to assume responsibility for the care and safeguarding of methadone, and use it only as prescribed [5]. Clinical stability also includes the elimination of sustained problematic drug or alcohol use and demonstration of mostly negative urine drug screens, a stable methadone dose, housing, employment, and/or a stable support system, and adherence to the methadone treatment agreement and program.Potential benefits of take home doses include improved retention in treatment for existing patients, making MMT more attractive to new patients, rewarding patients for abstinence or compliance with treatment, and giving patients more control over some aspects of their treatment. In addition, the quality of life may be improved through the reduction in daily attendance at a MMT clinic [4].However, while the privilege of take home doses has many potential benefits, it is not without potential problems. The issue of methadone diversion is a major concern for all MMT programs, as there is a substantial black marke
Surface Transport in Pre--Melted Films with Application to Grain--Boundary Grooving
Robert W. Style,M. Grae Worster
Physics , 2012, DOI: 10.1103/PhysRevLett.95.176102
Abstract: We present a new model of surface transport in premelted films that is applicable to a wide range of materials close to their melting point. We illustrate its use by applying it to the evolution of a grain boundary groove in a high vapour pressure material and show that Mullins's classical equation describing transport driven by gradients in surface curvature is reproduced asymptotically. The microscopic contact angle at the groove root is found to be modified over a thin boundary layer, and the apparent contact angle is determined. An explicit transport coefficient is derived that governs the evolution rate of systems controlled by surface transport through premelted films. The transport coefficient is found to depend on temperature and diverges as the bulk melting temperature is approached.
Formation of Chimneys in Mushy Layers: Experiment and Simulation
Anthony M. Anderson,Richard F. Katz,Grae Worster
Physics , 2011,
Abstract: In this fluid dyanmics video, we show experimental images and simulations of chimney formation in mushy layers. A directional solidification apparatus was used to freeze 25 wt % aqueous ammonium chloride solutions at controlled rates in a narrow Hele-Shaw cell (1mm gap). The convective motion is imaged with schlieren. We demonstrate the ability to numerically simulate mushy layer growth for direct comparison with experiments.
Floating Extensional Flows
Roiy Sayag,Samuel S. Pegler,M. Grae Worster
Physics , 2011, DOI: 10.1063/1.4747184
Abstract: This fluid dynamics video demonstrate the breaking of axisymmetry in the floating extensional flow of a non-Newtonian fluid.
Axisymmetric viscous gravity currents flowing over a porous medium
Melissa J. Spannuth,Jerome A. Neufeld,J. S. Wettlaufer,M. Grae Worster
Physics , 2009, DOI: 10.1017/S0022112008005223
Abstract: We study the axisymmetric propagation of a viscous gravity current over a deep porous medium into which it also drains. A model for the propagation and drainage of the current is developed and solved numerically in the case of constant input from a point source. In this case, a steady state is possible in which drainage balances the input, and we present analytical expressions for the resulting steady profile and radial extent. We demonstrate good agreement between our experiments, which use a bed of vertically aligned tubes as the porous medium, and the theoretically predicted evolution and steady state. However, analogous experiments using glass beads as the porous medium exhibit a variety of unexpected behaviours, including overshoot of the steady-state radius and subsequent retreat, thus highlighting the importance of the porous medium geometry and permeability structure in these systems.
Can a Massive Graviton be a Stable Particle  [PDF]
Andrew Beckwith
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.25043
Abstract: This document is based on a question asked in the Dark Side of the Universe 2010 conference in Leon, Mexico, when a researcher from India asked the author about how to obtain a stability analysis of massive gravitons. The answer to this question involves an extension of the usual Pauli_Fiertz Langrangian as written by Ortin, with non- zero graviton mass contributing to a relationship between the trace of a revised GR stress-energy tensor (assuming non- zero graviton mass), and the trace of a revised symmetric tensor times a tiny mass for a 4 dimensional graviton. The resulting analysis makes use of Visser’s treatment of a stress en-ergy tensor, with experimental applications discussed in the resulting analysis. If the square of frequency of a massive graviton is real valued and greater than zero, stability can be possibly confirmed experimentally.
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