5,761 research outputs found

    Short-scale turbulent fluctuations driven by the electron-temperature gradient in the national spherical torus experiment

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    Measurements with coherent scattering of electromagnetic waves in plasmas of the National Spherical Torus Experiment indicate the existence of turbulent fluctuations in the range of wave numbers k(perpendicular to)rho(e)=0.1-0.4, corresponding to a turbulence scale length nearly equal to the collisionless skin depth. Experimental observations and agreement with numerical results from a linear gyrokinetic stability code support the conjecture that the observed turbulence is driven by the electron-temperature gradient.X1155sciescopu

    Adolescent cannabis use, change in neurocognitive function, and high-school graduation: A longitudinal study from early adolescence to young adulthood

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    The main objective of this prospective longitudinal study was to investigate bidirectional associations between adolescent cannabis use (CU) and neurocognitive performance in a community sample of 294 young men from ages 13 to 20 years. The results showed that in early adolescence, and prior to initiation to CU, poor short-term and working memory, but high verbal IQ, were associated with earlier age of onset of CU. In turn, age of CU onset and CU frequency across adolescence were associated with (a) specific neurocognitive decline in verbal IQ and executive function tasks tapping trial and error learning and reward processing by early adulthood and (b) lower rates of high-school graduation. The association between CU onset and change in neurocognitive function, however, was found to be accounted for by CU frequency. Whereas the link between CU frequency across adolescence and change in verbal IQ was explained (mediated) by high school graduation, the link between CU frequency and tasks tapping trial and error learning were independent from high school graduation, concurrent cannabis and other substance use, adolescent alcohol use, and externalizing behaviors. Findings support prevention efforts aimed at delaying onset and reducing frequency of CU

    Interpreting and acting upon home blood pressure readings: A qualitative study

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    This article is made available through the Brunel Open Access Publishing Fund. Copyright @ 2013 Vasileiou et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: Recent guidelines recognize the importance of home blood pressure monitoring (HBPM) as an adjunct to clinical measurements. We explored how people who have purchased and use a home blood pressure (BP) monitor make sense of, and act upon, readings and how they communicate with their doctor about the practice of home monitoring. Methods: A qualitative study was designed and participants were purposively recruited from several areas in England, UK. Semi-structured in-depth interviews were conducted with 18 users of home BP monitors. The transcribed data were thematically analysed. Results: Interpretation of home BP readings is complex, and is often characterised by uncertainty. People seek to assess value normality using ‘rules of thumb’, and often aim to identify the potential causes of the readings. This is done by drawing on lay models of BP function and by contextualising the readings to personal circumstances. Based on the perceived causes of the problematic readings, actions are initiated, mostly relating to changes in daily routines. Contacting the doctor was more likely when the problematic readings persisted and could not be easily explained, or when participants did not succeed in regulating their BP through their other interventions. Most users had notified their doctor of the practice of home monitoring, but medical involvement varied, with some participants reporting disinterest or reservations by doctors. Conclusions: Involvement from doctors can help people overcome difficulties and resolve uncertainties around the interpretation of home readings, and ensure that the rules of thumb are appropriate. Home monitoring can be used to strengthen the patient-clinician relationship

    Fine structural changes of fluid catalytic catalysts and characterization of coke formed resulting from heavy oil devolatilization

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    Coke formation from heavy oil cracking and the associated change in the porous structure of fluid catalytic cracking (FCC) catalysts has been studied using a comprehensive range of techniques, including 2D and 3D imaging and carbon/coke characterization techniques. The carbon/coke formed from heavy oil devolatilization has been investigated with a range of oil-to-FCC catalyst ratios (1:3, 1:2, 1:1, 2:1 and 3:1) to simulate the ageing of FCC catalysts in an operating oil refinery. Carbon/coke was formed on all used FCC catalyst samples and was found to generally increase in quantity with the increasing oil-to-FCC catalyst ratios. Coke formation has been correlated with the observed porosity change of the FCC catalyst. Higher quantities of carbon/coke formed on the FCC catalyst due to higher oil-to-FCC catalyst ratios (simulated increase in time on-stream) leads to a decrease of total pore volume and surface area. X-Ray computed tomography (X-Ray CT) studies allowed 3-dimensional imaging of used catalyst particles and showed that the zeolite component of the FCC catalyst remains evenly distributed throughout the FCC particle from the centre to the exterior for pristine and used FCC catalyst particles. This technique showed that while the interior porous structure of the FCC catalyst particle is not affected by the coking, the exterior porous structure is substantially modified for all used FCC catalyst samples. This process of pore collapse and/or clogging at the surface of the particles is likely to have a significant effect on the deactivation of FCC catalysts that is commonly observed. The deeper insight into this process gained through this study is important for understanding how FCC catalysts change with time-on-stream and eventually deactivate and may allow for future catalysts to be developed that are more resistant to deactivation

    The role of the exit in the initial screening of investment opportunities: The case of business angel syndicate gatekeepers

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    The exit process has been largely ignored in business angel research.. The practitioner community identifies the difficulty in achieving exits as the most pressing problem for investors. This has been attributed to the failure of investors to adopt an exit-centric approach to investing. The validity of this claim is examined via a study of the investment approach of 21 ‘gatekeepers’ (managers) of angel groups in Scotland and Northern Ireland. Most gatekeepers say that they do consider the exit when they invest. However, this is contradicted by a verbal protocol analysis which indicates that the exit is not a significant consideration in their initial screening process. The small number of exits achieved by the groups is consistent with the general lack of an exit-centric approach to investing. Only three groups exhibit evidence of a strong exit-centric approach to investing. The lack of exits may have a negative impact on the level of future angel investment activity

    A Randomized Clinical Trial Comparing Individual Cognitive Behavioral Therapy and Child-Centered Therapy for Child Anxiety Disorders

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    This study compared individual cognitive behavioral therapy (CBT) and a supportive child-centered therapy (CCT) for child anxiety disorders on rates of treatment response and recovery at posttreatment and 1-year follow-up, as well as on real-world measures of emotional functioning. Youth (N = 133; ages 9–14) with anxiety disorders (generalized, separation, and/or social anxiety) were randomized using a 2:1 ratio to CBT (n = 90) or CCT (n = 43), which served as an active comparison. Treatment response and recovery at posttreatment and 1-year follow-up were assessed by Independent Evaluators, and youth completed ecological momentary assessment of daily emotions throughout treatment. The majority of youth in both CBT and CCT were classified as treatment responders (71.1% for CBT, 55.8% for CCT), but youth treated with CBT were significantly more likely to fully recover, no longer meeting diagnostic criteria for any of the targeted anxiety disorders and no longer showing residual symptoms (66.7% for CBT vs. 46.5% for CCT). Youth treated with CBT also reported significantly lower negative emotions associated with recent negative events experienced in daily life during the latter stages of treatment relative to youth treated with CCT. Furthermore, a significantly higher percentage of youth treated with CBT compared to CCT were in recovery at 1-year follow-up (82.2% for CBT vs. 65.1% for CCT). These findings indicate potential benefits of CBT above and beyond supportive therapy on the breadth, generalizability, and durability of treatment-related gains

    Creating Awareness of Sleep-Wake Hours by Gamification

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    This book constitutes the refereed proceedings of the 11th International Conference on Persuasive Technology, PERSUASIVE 2016, held in Salzburg, Austria, in April 2016

    Epidemic space

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    The aim of this article is to highlight the importance of 'spatiality' in understanding the materialization of risk society and cultivation of risk sensibilities. More specifically it provides a cultural analysis of pathogen virulence (as a social phenomenon) by means of tracing and mapping the spatial flows that operate in the uncharted zones between the microphysics of infection and the macrophysics of epidemics. It will be argued that epidemic space consists of three types of forces: the vector, the index and the vortex. It will draw on Latour's Actor Network Theory to argue that epidemic space is geared towards instability when the vortex (of expanding associations and concerns) displaces the index (of finding a single cause)
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