The Physics of Turbulence in the Boundary Layer

The geometry of the velocity field in a numerically simulated incompressible turbulent boundary layer over a flat plate at Re theta=670 has been studied using the invariants of the velocity gradient tensor. These invariants are computed at every grid point in the flow and used to form the discriminant. Of primary interest are those regions in the flow where the discriminant is positive; regions where, according to the characteristic equation, the eigenvalues of the velocity gradient tensor are complex. An observer moving with a frame of reference which is attached to a fluid particle lying within such a region would see a local flow pattern of the type stable-focus-stretching or unstable-focus-compressing. When the flow is visualized this way, continuous, connected, large-scale structures are revealed that extend from the point just below the buffer layer out to the beginning of the wake region. These structures are aligned with the mean shear close to the wall and arch in the cross-stream direction away from the wall. In some cases the structures observed are very similar to to the hairpin eddy vision of boundary layer structure proposed by Theodorsen. That the structure of the flow is revealed more effectively by the discriminant rather than by the vorticity is important and adds support to recent observations of the discriminant in a channel flow simulation. Of particular importance is the fact that the procedure does not require the use of an arbitrary threshold in the discriminant. Further analysis using computer flow visualization shows a high degree of spatial correlation between regions of positive discriminant, extreme negative pressure fluctuations and large instantaneous values of Reynolds shear stress

Audio and visual characteristics of television news broadcasting: their effects on opinion change

The audio-visual character of television was used as the conceptual focus of this examination of television news broadcasting. The research comprised both a macro and micro level analysis. On the macro level, a study was undertaken to examine the influences of the cultural context of broadcasting with special reference to the structure of television and its news organizations upon the formats and content of television news programmes. A comparative content analysis was carried out of the principle evening newscast during one fortnight of news broadcast by the public and the private broadcast networks, in Britain and Canada, and the NBC in the United States. A special "code" was developed for this purpose which would categorize not only content but also format, with a special emphasis on the relative role of the commentary and the visuals. Comparison between the countries revealed differences in both content and format, pointing to different cultural emphasis upon specific issues. Differences in the formats used in the news revealed a greater trend to entertainment values - particularly the use of the action visuals and the newsreader in the more commercialised cultural settings. Within Canada and Britain, those differences between the public and private sectors which did occur, had to do with the style of news presentation, not with its contents, pointing to the standardization of production within the news organization under the conditions of competition and inter-dependence inherent in the structure of broadcasting in these countries. The micro level study examined the effects of the visual and auditory components of the news story by means of an experimental study. A BBC type newscast about demonstrations was systematically varied in six experimental conditions to examine the relative effects and their interactions of modality, consistency or inconsistency between the modalities and of content bias on retention and opinion change. Specifically designed verb/visual techniques of measuring the impression and the visual retention of the event were used. The results showed that viewers shifted their opinions in the direction of the story bias. Visual information increased the impact of the commentary and had its effects principally on the affective component of the opinion. Where visual information and commentary were at variance, the visuals had greater impact on the affective component, with the commentary influencing the cognitive or belief component more. The research points to the need to extend the concept of bias beyond that traditionally used in communication research, not only beyond content to style of presentation, but also to an examination of the different cultural and organizational factors within the industry in which lead to variations in the emphasis upon the visual element within news programmes

Media Literacy in the Risk Society: Toward a Risk Reduction Strategy

The idea of media literacy prompts an increasingly divisive debate between educators who wish to protect children from the commercialization of global markets and those who challenge critical media studies as misguided, outdated, and ineffective. We have provided a historical overview of changing conceptions of media literacy as preparation and protection in market society, arguing that contemporary concerns about children’s fast food marketing and sedentary lifestyles call for new approaches to the education of citizen‐consumers in a risk society. Our case study demonstrates that a media education programme can provide scaffolding for children’s critical thinking about their sedentary lifestyles and media consumption. Key words: sedentary lifestyles, advertising literacy, media consumption, displacement effects. La notion d’initiation aux médias suscite un débat de plus en plus animé entre, d’une part, les intervenants éducatifs qui désirent protéger les enfants contre la mondialisation de la culture commerciale et, d’autre part, ceux pour qui les études critiques des médias sont peu judicieuses, périmées et inefficaces. Les auteurs présentent un survol historique de l’évolution des façons de voir l’initiation aux médias comme outil de préparation et de protection dans une société marchande et soutiennent que les inquiétudes actuelles au sujet du marketing des repas‐minute auprès des enfants et des modes de vie sédentaire requièrent de nouvelles approches de l’éducation des consommateurs‐citoyens dans une société à risque. L’étude de cas présentée ici démontre qu’un programme d’initiation aux médias peut permettre de charpenter l’esprit critique des enfants au sujet de leur mode de vie sédentaire et de leur consommation des médias. Mots clés : mode de vie sédentaire, littératie en matière de publicité, consommation des médias, effets de déplacement.

The Sequential Organ Failure Assessment score for predicting outcome in patients with severe sepsis and evidence of hypoperfusion at the time of emergency department presentation

Objectives Organ failure worsens outcome in sepsis. The Sequential Organ Failure Assessment (SOFA) score numerically quantifies the number and severity of failed organs. We examined the utility of the SOFA score for assessing outcome of patients with severe sepsis with evidence of hypoperfusion at the time of emergency department (ED) presentation. Design Prospective observational study. Setting Urban, tertiary ED with an annual census of >110,000. Patients ED patients with severe sepsis with evidence of hypoperfusion. Inclusion criteria: suspected infection, two or more criteria of systemic inflammation, and either systolic blood pressure 4 mmol/L. Exclusion criteria age <18 years or need for immediate surgery. Interventions SOFA scores were calculated at ED recognition (T0) and 72 hours after intensive care unit admission (T72). The primary outcome was in-hospital mortality. The area under the receiver operating characteristic curve was used to evaluate the predictive ability of SOFA scores at each time point. The relationship between Δ SOFA (change in SOFA from T0 to T72) was examined for linearity. Results A total of 248 subjects aged 57 ± 16 years, 48% men, were enrolled over 2 years. All patients were treated with a standardized quantitative resuscitation protocol; the in-hospital mortality rate was 21%. The mean SOFA score at T0 was 7.1 ± 3.6 points and at T72 was 7.4 ± 4.9 points. The area under the receiver operating characteristic curve of SOFA for predicting in-hospital mortality at T0 was 0.75 (95% confidence interval 0.68 - 0.83) and at T72 was 0.84 (95% confidence interval 0.77-0.90). The Δ SOFA was found to have a positive relationship with in-hospital mortality. Conclusions The SOFA score provides potentially valuable prognostic information on in-hospital survival when applied to patients with severe sepsis with evidence of hypoperfusion at the time of ED presentation

Assessing the Field of Media Education in British Columbia; a survey of teachers in the present-day BC school system

Abstract The role and impact of audio-visual media have been a matter of considerable debate among Canadian educators for more than sixty years as aids to communicating the curriculum, as forms of artistic and cultural identity, and as part of the critical cultural pedagogies of a liberal education. In British Columbia, the Canadian Association for Media Educators was forged in the early 1990&apos;s and later participated in preparing an integrated media education curriculum for Grades K to 12. Although this initiative legitimated media education within classroom practice, it was not mandatory. This survey of British Columbia teachers set out to determine, why how and to what degree teachers incorporated media education pedagogy into their daily practice. Our survey of eighty teachers in Vancouver and the Lower Mainland indicated that although media literacy has been successfully implemented within the BC school curriculum, its uptake and development is not without challenges. Both a lack of training and resources, combined with the already-busy schedule of teachers, has meant that media literacy remains a secondary objective within Social Studies, English or Humanities lessons. Indeed, many of the specified media education Prescribed Learning Outcomes (PLOs) that teachers believe important are ignored or untaught. With growing evidence that some of the critical literacy ambitions of the integrated curriculum were not finding their way into the classroom we conclude by explaining how our &apos;tune-out the screen&apos; initiative provided a focal point for reemphasizing critical media-education objectives in BC