991 resultados para Bubble rise velocity
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We report on our findings based on the analysis of observations of the Type II-L supernova LSQ13cuw within the framework of currently accepted physical predictions of core-collapse supernova explosions. LSQ13cuw was discovered within a day of explosion, hitherto unprecedented for Type II-L supernovae. This motivated a comparative study of Type II-P and II-L supernovae with relatively well-constrained explosion epochs and rise times to maximum (optical) light. From our sample of twenty such events, we find evidence of a positive correlation between the duration of the rise and the peak brightness. On average, SNe II-L tend to have brighter peak magnitudes and longer rise times than SNe II-P. However, this difference is clearest only at the extreme ends of the rise time versus peak brightness relation. Using two different analytical models, we performed a parameter study to investigate the physical parameters that control the rise time behaviour. In general, the models qualitatively reproduce aspects of the observed trends. We find that the brightness of the optical peak increases for larger progenitor radii and explosion energies, and decreases for larger masses. The dependence of the rise time on mass and explosion energy is smaller than the dependence on the progenitor radius. We find no evidence that the progenitors of SNe II-L have significantly smaller radii than those of SNe II-P.
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Wavelet entropy assesses the degree of order or disorder in signals and presents this complex information in a simple metric. Relative wavelet entropy assesses the similarity between the spectral distributions of two signals, again in a simple metric. Wavelet entropy is therefore potentially a very attractive tool for waveform analysis. The ability of this method to track the effects of pharmacologic modulation of vascular function on Doppler blood velocity waveforms was assessed. Waveforms were captured from ophthalmic arteries of 10 healthy subjects at baseline, after the administration of glyceryl trinitrate (GTN) and after two doses of N(G)-nitro-L-arginine-methyl ester (L-NAME) to produce vasodilation and vasoconstriction, respectively. Wavelet entropy had a tendency to decrease from baseline in response to GTN, but significantly increased after the administration of L-NAME (mean: 1.60 ± 0.07 after 0.25 mg/kg and 1.72 ± 0.13 after 0.5 mg/kg vs. 1.50 ± 0.10 at baseline, p < 0.05). Relative wavelet entropy had a spectral distribution from increasing doses of L-NAME comparable to baseline, 0.07 ± 0.04 and 0.08 ± 0.03, respectively, whereas GTN had the most dissimilar spectral distribution compared with baseline (0.17 ± 0.08, p = 0.002). Wavelet entropy can detect subtle changes in Doppler blood velocity waveform structure in response to nitric-oxide-mediated changes in arteriolar smooth muscle tone.
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The asymmetries observed in the line profiles of solar flares can provide important diagnostics of the properties and dynamics of the flaring atmosphere. In this paper the evolution of the Hα and Ca ii λ8542 lines are studied using high spatial, temporal, and spectral resolution ground-based observations of an M1.1 flare obtained with the Swedish 1 m Solar Telescope. The temporal evolution of the Hα line profiles from the flare kernel shows excess emission in the red wing (red asymmetry) before flare maximum and excess in the blue wing (blue asymmetry) after maximum. However, the Ca ii λ8542 line does not follow the same pattern, showing only a weak red asymmetry during the flare. RADYN simulations are used to synthesize spectral line profiles for the flaring atmosphere, and good agreement is found with the observations. We show that the red asymmetry observed in Hα is not necessarily associated with plasma downflows, and the blue asymmetry may not be related to plasma upflows. Indeed, we conclude that the steep velocity gradients in the flaring chromosphere modify the wavelength of the central reversal in the Hα line profile. The shift in the wavelength of maximum opacity to shorter and longer wavelengths generates the red and blue asymmetries, respectively.
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We describe five children who died of clinical rabies in a three month period (September to November 2011) in the Queen Elizabeth Central Hospital. From previous experience and hospital records, this number of cases is higher than expected. We are concerned that difficulty in accessing post-exposure prophylaxis (PEP) rabies vaccine may be partly responsible for this rise. We advocate: (a) prompt course of active immunisation for all patients with significant exposure to proven or suspected rabid animals. (b) the use of an intradermal immunisation regime that requires a smaller quantity of the vaccine than the intramuscular regime and gives a better antibody response. (c) improved dog rabies control measures.
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Acute respiratory infections are the leading cause of global child mortality. In the developing world, nasal oxygen therapy is often the only treatment option for babies who are suffering from respiratory distress. Without the added pressure of bubble Continuous Positive Airway Pressure (bCPAP) which helps maintain alveoli open, babies struggle to breathe and can suffer serious complications, and frequently death. A stand-alone bCPAP device can cost $6,000, too expensive for most developing world hospitals. Here, we describe the design and technical evaluation of a new, rugged bCPAP system that can be made in small volume for a cost-of-goods of approximately $350. Moreover, because of its simple design--consumer-grade pumps, medical tubing, and regulators--it requires only the simple replacement of a <$1 diaphragm approximately every 2 years for maintenance. The low-cost bCPAP device delivers pressure and flow equivalent to those of a reference bCPAP system used in the developed world. We describe the initial clinical cases of a child with bronchiolitis and a neonate with respiratory distress who were treated successfully with the new bCPAP device.
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Hypothesis: As the anterior and posterior semicircular canals are vital to the regulation of gaze stability, particularly during locomotion or vehicular travel, we tested whether the high velocity vestibulo‐ocular reflex (VOR) of the three ipsilesional semicircular canals elicited by the modified Head Impulse Test would correlate with subjective dizziness or vertigo scores after vestibular neuritis (VN). Background: Recovery following acute VN varies with around half reporting persistent symptoms long after the acute episode. However, an unanswered question is whether chronic symptoms are associated with impairment of the high velocity VOR of the anterior or posterior canals. Methods: Twenty patients who had experienced an acute episode of VN at least three months earlier were included in this study. Participants were assessed with the video head impulse test (vHIT) of all six canals, bithermal caloric irrigation, the Dizziness Handicap Inventory (DHI) and the Vertigo Symptoms Scale short‐form (VSS). Results: Of these 20 patients, 12 felt that they had recovered from the initial episode whereas 8 did not and reported elevated DHI and VSS scores. However, we found no correlation between DHI or VSS scores and the ipsilesional single or combined vHIT gain, vHIT gain asymmetry or caloric paresis. The high velocity VOR was not different between patients who felt they had recovered and patients who felt they had not. Conclusions: Our findings suggest that chronic symptoms of dizziness following VN are not associated with the high velocity VOR of the single or combined ipsilesional horizontal, anterior or posterior semicircular canals.
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This interdisciplinary study examines the contribution that a book-review magazine makes to the cultural identity of its readers. It is the result of reflections on the cultural work of Books in Canada , on whether or not this periodical was a cultural worksite and if that is the case how it performed that cultural work. In addition, it interrogates factors that may have contributed to the magazine's demise. The study affirms that Books in Canada, a cultural enterprise from 1971 to 2008, mirrored and helped to shape book and literary culture in Canada through its circulation, through the personalities of its editors, through its front covers and through its reviewers and their reviews. Furthermore, it proposes that the demise of the enterprise was due to a combination of factors. The study begins with an introduction to book reviewing and special-interest magazines. Chapter I examines the interplay between selected visual and textual contents published in Books in Canada in its founding years. These components reflected and helped to fuel the cultural nationalism that was sweeping Canada subsequent to the 1967 World's Fair in Montreal. There were also persistent rumours and comments about the magazine that caused certain"cracks in the foundation" to appear. Chapter II compares the aims and editorial challenges of Val Clery, founder of Books in Canada , with those of Adrien Thério, founder of Lettres québécoises, and of the editors of the magazines' twentieth-anniversary issues, Paul Stuewe in the case of the former and André Vanasse in the case of the latter. Evidence in the content of the magazine, editorial and otherwise, indicated that the"contracts" that the editors made with their readers over the years were similar, to reflect and shape a cultural identity, but the result of their"projects," that is, the nature of those identities, was distinctly different. Evidently then, personal aims, preferences and political leanings of editors can have a major impact on the content of a book-review magazine and thus on the cultural work that it does. Therefore, in Chapter III, I focus on selected contents published during the tenures of two of Books in Canada 's key editors, Paul Stuewe and Olga Stein, in order to understand ways that their choices constituted a form of cultural work. The second part of this chapter moves from an analysis of the cultural work of editors to an examination of the cultural work of reviewers. Here, through a close-reading of a selection of reviews published in Books in Canada, and in other periodicals, I argue that reviewers do cultural work in the way that they negotiate their presence in a review, and in how they signal that presence through lexical choices and through the degree of intellectual interaction that they invite. Intellectual interaction is at the core of Chapter IV.This chapter consists of close readings of some of the"billboards" of the enterprise, that is, the front covers of Books in Canada , in order to show how these important components do cultural work by requiring readers to make an intellectual leap from image to text. Chapter V suggests that book reviews, the company's"bills of goods," do cultural work in much the same way as the paratexts of a book. One of my own reviews is offered as a case-study along with a number of other reviews of how central components of a book-review magazine do cultural work through the illocutionary force of their sentences. The first part of Chapter VI, the final chapter, measures the legacy of the magazine, in particular, the annual Books in Canada First Novel Award. Created in 1976, this prize is awarded to the author of the novel judged by a Books in Canada prize committee to be the best first novel in English of the year. The second part of Chapter VI sheds light on factors that may have contributed to the closure of the enterprise, including the copyright uproar that accompanied the agreement that Adrian Stein, publisher of Books in Canada and Olga Stein's husband, made in 2001 with the online book merchant, Amazon.com. Furthermore, this penultimate section of the study suggests that one of the most important factors in the magazine's demise was the decision by the Steins to exploit their position as owners, publisher, and editor of a book-review periodical, a government-subsidized one at that, to publish their own lengthy pre-trial defense of Conrad Black. The chapter then zooms back from the particular to the general with a broader consideration of the impact of technology and globalization on the book industry and on the ability of Books in Canada to survive in any form, print or digital.
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Une évaluation de l'évaluabilité du programme d'intervention Son-Rise a été réalisée. Ce programme de stimulation relationnelle, basé à la maison et dirigé par les parents, s'adresse aux enfants autistes et à leur famille, et vise à développer les habiletés sociales par le jeu en suivant les intérêts de l'enfant. Le peu de littérature scientifique disponible au sujet de ce programme fait ressortir la pertinence de l'évaluer en commençant par une évaluation de son évaluabilité. Une analyse des documents principaux du programme ainsi que dix entrevues avec des parties prenantes variées ont mené à des recommandations pour les évaluations futures. Le programme Son-Rise serait suffisamment bien construit et stable pour être évaluable, mais son contexte d'implantation pourrait être un obstacle à l'évaluation.
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Senior thesis written for Oceanography 445
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Senior thesis written for Oceanography 445
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The aim of this paper is to reflect on how conceptions of networked learning have changed, particularly in relation to educational practices and uses of technology, that can nurture new ideas of networked learning to sustain multiple and diverse communities of practice in institutional settings. Our work is framed using two theoretical frameworks: Giddens's (1984) structuration theory and Callon & Latour's (1981) Actor Network Theory as critiqued by Fox (2005) in relation to networked learning. We use these frameworks to analyse and critique ideas of networked learning embodied in both cases. We investigate three questions: (a) the role of individual agency in the development of networked learning; (b) the impact of technological developments on approaches to supporting students within institutional infrastructures; and (c) designing networked learning to incorporate Web 2.0 practices that sustain multiple communities and foster engagement with knowledge in new ways. We use an interpretivist approach by drawing on experiential knowledge of the Masters programme in Networked Collaborative Learning and the decision making process of designing the virtual graduate schools. At this early stage, we have limited empirical data related to the student experience of networked learning in current and earlier projects. Our findings indicate that the use of two different theoretical frameworks provided an essential tool in illuminating, situating and informing the process of designing networked learning that involves supporting multiple and diverse communities of practice in institutional settings. These theoretical frameworks have also helped us to analyze our existing projects as case studies and to problematize and begin to understand the challenges we face in facilitating the participation of research students in networked learning communities of practice and the barriers to that participation. We have also found that this process of theorizing has given us a way of reconceptualizing communities of practice within research settings that have the potential to lead to new ideas of networked learning.
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This article reflects growing academic interest in the careers and historical significance of professional women town planners, an interest clearly registered in Planning Perspectives and other publications. Unlike other women town planners, however, the career of Monica Felton remains largely obscure. It was certainly short-lived, beginning as it did on the London County Council in 1937 and ending spectacularly while she was Chairman of Stevenage Development Corporation in 1951. Felton became an outcast from both her profession and her country when she gave up on new town development to campaign against British and American involvement in the Korean War in 1951. This article emphasizes her distinctive contribution to the evolving roles of women in British town planning during the mid-twentieth century and shows how this contribution was obscured by her fall from grace.