874 research outputs found

    New Measurements of Venus Winds with Ground-Based Doppler Velocimetry at CFHT

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    operations with observations from the ground using various techniques and spectral domains (Lellouch and Witasse, 2008). We present an analysis of Venus Doppler winds at cloud tops based on observations made at the Canada France Hawaii 3.6-m telescope (CFHT) with the ESPaDOnS visible spectrograph. These observations consisted of high-resolution spectra of Fraunhofer lines in the visible range (0.37-1.05 μm) to measure the winds at cloud tops using the Doppler shift of solar radiation scattered by cloud top particles in the observer's direction (Widemann et al., 2007, 2008). The observations were made during 19-20 February 2011 and were coordinated with Visual Monitoring Camera (VMC) observations by Venus Express. The complete optical spectrum was collected over 40 spectral orders at each point with 2-5 seconds exposures, at a resolution of about 80000. The observations included various points of the dayside hemisphere at a phase angle of 67°, between +10° and -60° latitude, in steps of 10° , and from +70° to -12° longitude relative to sub-Earth meridian in steps of 12°. The Doppler shift measured in scattered solar light on Venus dayside results from two instantaneous motions: (1) a motion between the Sun and Venus upper cloud particles; (2) a motion between the observer and Venus clouds. The measured Doppler shift, which results from these two terms combined, varies with the planetocentric longitude and latitude and is minimum at meridian ΦN = ΦSun - ΦEarth where the two components subtract to each other for a pure zonal regime. Due to the need for maintaining a stable velocity reference during the course of acquisition using high resolution spectroscopy, we measure relative Doppler shifts to ΦN. The main purpose of our work is to provide variable wind measurements with respect to the background atmosphere, complementary to simultaneous measurements made with the VMC camera onboard the Venus Express. We will present first results from this work, comparing with previous results by the CFHT/ESPaDOnS and VLT-UVES spectrographs (Machado et al., 2012), with Galileo fly-by measurements and with VEx nominal mission observations (Peralta et al., 2007, Luz et al., 2011). Acknowledgements: The authors acknowledge support from FCT through projects PTDC/CTE-AST/110702/2009 and PEst-OE/FIS/UI2751/2011. PM and TW also acknowledge support from the Observatoire de Paris. Lellouch, E., and Witasse, O., A coordinated campaign of Venus ground-based observations and Venus Express measurements, Planetary and Space Science 56 (2008) 1317-1319. Luz, D., et al., Venus's polar vortex reveals precessing circulation, Science 332 (2011) 577-580. Machado, P., Luz, D. Widemann, T., Lellouch, E., Witasse, O, Characterizing the atmospheric dynamics of Venus from ground-based Doppler velocimetry, Icarus, submitted. Peralta J., R. Hueso, A. Sánchez-Lavega, A reanalysis of Venus winds at two cloud levels from Galileo SSI images, Icarus 190 (2007) 469-477. Widemann, T., Lellouch, E., Donati, J.-F., 2008, Venus Doppler winds at Cloud Tops Observed with ESPaDOnS at CFHT, Planetary and Space Science, 56, 1320-1334

    Susceptibility of microcosm subgingival dental plaques to lethal photosensitisation

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    Photodynamic therapy (PDT) offers potential as a non-invasive treatment of periodontal 15 disease. In this study, microcosm biofilms were grown in vitro under conditions designed 16 to mimic subgingival plaques typically found in patients with periodontitis. To 17 investigate potential PDT modalities, biofilms were exposed to light from a helium/neon 18 laser in conjunction with a photosensitiser, toluidine blue (TBO), at varying output and 19 concentration, respectively. To determine cytotoxic effects, viability profiling was 20 undertaken on whole biofilms using standard plating methods, and on horizontal cross-21 sections of biofilms using confocal laser-scanning microscopy (CLSM) in conjunction 22 with a differential viability stain. A light energy dose of 94.5 J in combination with 81.7 23 .M TBO was found to be optimal, achieving significant kills of over 97%. CLSM 24 enabled visualisation of the effects of PDT in three dimensions. Viability profiling of the 25 CLSM images revealed that lethal photosensitisation was most effective in the upper 26 layers of biofilm. PDT was found to reduce the viability of subgingivally-modelled 27 plaques in vitro by a similar magnitude to chlorhexidine digluconate (CHL), which is 28 commonly used to treat periodontal disease. The findings of this study indicate that PDT 29 may be an effective alternative to conventional modalities in the treatment of periodontal 30 disease. 3

    Purposeful Outdoor Learning Empowers Children to Deal with School Transitions.

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    UK schoolchildren are vulnerable to transitional stress between primary and secondary school, which may impact negatively upon their psychological health and academic achievement. This is experienced most acutely by children from ethnic minorities and lower socio-economic status (SES) households. Outdoor Adventure (OA) residential programmes are purported to develop behavioural adaptations which enable positive educational transitions of children. Personal, social and academic skills (self-reliance, getting along with others, curriculum alignment) may be best acquired through bespoke nature-based residential OA programmes. A mixed methods study evaluated the efficacy of a bespoke OA programme for developing school children's psychological well-being and self-determination during their transition into secondary school. Participants were representantives of ethnic minorities and lower SES groups. A bespoke OA residential programme achieved the strongest scale of change in children's psychological well-being (F (30,69) = 1.97 < 0.05) and self-determination (effect size 0.25) compared to a generic OA residential and a non-OA school-based induction programme. Qualitative testimonies illuminated personal experiences and processes underpinning the perceived changes in the self-determination domains of Autonomy (the capacity to self-direct learning), Competence (the ability to complete tasks) and Relatedness (developing connections with others). Providing early opportunities for children to take control for their own learning through nature-based tailored OA programming improves their psychological well-being and adaptability to combat transitional stress

    Trajectories of Resilience in University Inductees following Outdoor Adventure (OA) Residential Programmes

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    Even before COVID-19, university inductees were vulnerable to transitional stressors, which impact upon their psychological well-being and ability to complete their studies. Resilience, as a psychological construct, may be analogous to holding the functioning that supports higher-level academic performance in twenty-first century higher education (HE). Given the significant investment HE requires, coupled with students’ capacity to develop their resilience, universities may be expected to promote psychological resilience in new students. Linking HE to resilience, outdoor adventure (OA) residential programmes have enabled inductees to build components of resilience (i.e., increased self-perception, feelings of control, and intrapersonal relationships) that may heighten their immediate and longer-term academic performance. Yet, few studies have examined the sustainability of these effects. Across five annual cohorts, the self-perceived resilience of 2500 inductees was profiled across three time-point trajectories: (i) pre-OA programme, (ii) post-OA programme, and (iii) three months post-OA programme. Further, the functionality of inductees’ enduring resilience was evaluated for predicting their prospective academic performance at the end of their first year of study. Students’ self-perceived resilience, well-being, and positive recollection of OA experiences reflected their bounce-back ability and a healthy trajectory of productive functioning. Students reporting higher levels of resilience after three months of following the programme were more likely to achieve better prospective academic outcomes. The large sample size ensured that a powerful detection of change was established across time. However, given the absence of a comparison condition across all time points, any lasting improvements in students’ resilience was unable to be attributed to the OA programme. Nonetheless, the results give significant grounds for further research in this direction, including the study of more distinct narrative enquiries at follow-up. In this way, pedagogical practices, supporting effective interventions, may be deployed with incoming students, with the aim of building and maintaining students’ on-going resilience across different learning contexts

    Outdoor Adventure Builds Resilient Learners for Higher Education: A Quantitative Analysis of the Active Components of Positive Change.

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    The inability of young adults to adapt to university life has been attributed to their declining resilience. Resilience refers to any individuals' capacity to change or modify behaviour in response to environmental hazards, so they thrive. Outdoor Adventure (OA) residential programmes have helped higher education inductees to acquire skills associated with resilience such as increased self-perception, better interpersonal relationships. However, this study addresses important gaps in existing literature by deploying a high-quality research design to examine the short-term impact of OA experiences on inductees' resilience and to identify the active components of those experiences that best cultivate inductees' adaptive capabilities. Multivariate analyses evaluated the efficacy of OA programming to build the resilience of over 2500 inductees. Significant positive gains were reported in the resilience of inductees attending 1-week residential OA programmes measured by an Effect size (ES) = 0.38 and 6.29% increase. Compared to students inducted at university, this represented an 8.35% greater increase in resilience (ES difference = -0.526). Camp-based experiences such as mastering new skills, developing new relationships and being female predicted heightened resilience. A defined blend of embodied, adventure-based meaningful challenges provides a template for helping university inductees to re-adjust, grow and persevere

    Type of diet modulates the metabolic response to sleep deprivation in rats

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    <p>Abstract</p> <p>Background</p> <p>Evidence suggests that sleep loss is associated with an increased risk of obesity and diabetes; however, animal models have failed to produce weight gain under sleep deprivation (SD). Previous studies have suggested that this discrepancy could be due to more extreme SD conditions in experimental animals, their higher resting metabolic rate than that of humans, and the decreased opportunity for animals to ingest high-calorie foods. Thus, our objective was to determine whether diets with different textures/compositions could modify feeding behavior and affect the metabolic repercussions in SD in rats.</p> <p>Methods</p> <p>Three groups of male rats were used: one was designated as control, one was sleep deprived for 96 h by the platform technique (SD-96h) and one was SD-96h followed by a 24-h recovery (rebound). In the first experiment, the animals were fed chow pellets (CPs); in the second, they received high-fat diet and in the third, they were fed a liquid diet (LD).</p> <p>Results</p> <p>We observed that SD induces energy deficits that were related to changes in feeding behavior and affected by the type of diet consumed. Regardless of the diet consumed, SD consistently increased animals' glucagon levels and decreased their leptin and triacylglycerol levels and liver glycogen stores. However, such changes were mostly avoided in the rats on the liquid diet. SD induces a wide range of metabolic and hormonal changes that are strongly linked to the severity of weight loss.</p> <p>Conclusions</p> <p>The LD, but not the CP or high-fat diets, favored energy intake, consequently lessening the energy deficit induced by SD.</p

    Isotropy of the velocity of light and the Sagnac effect

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    In this paper, it is shown, using a geometrical approach, the isotropy of the velocity of light measured in a rotating frame in Minkowski space-time, and it is verified that this result is compatible with the Sagnac effect. Furthermore, we find that this problem can be reduced to the solution of geodesic triangles in a Minkowskian cylinder. A relationship between the problems established on the cylinder and on the Minkowskian plane is obtained through a local isometry.Comment: LaTeX, 13 pages, 3 eps figures; typos corrected, added references, minor changes; to appear in "Relativity in Rotating Frames", ed. G. Rizzi G. and M.L. Ruggiero, Kluwer Academic Publishers, Dordrecht (2003

    Siblings, Stories and the Self: the sociological significance of young people’s sibling relationships

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    This article explores the significance of intra-generational ties with siblings to sociological understandings of the formation of social identity and sense of self in young people’s lives. Drawing on data from a qualitative study exploring young people’s sense of who they are and who they have the potential to become in the future, it is demonstrated that young people’s identities are often constructed in relation to how they are similar to or different from their sibling(s). Literature expounding the role of stories in the construction of the self is used to suggest that the comparing that is at the heart of the relational construction of sibling identities can occur through the telling and re-telling of family stories within the politics and power dynamics of existing relationships. The article concludes by suggesting that sibling relationships be conceptualized as part of a web of relationships in which young people are embedded
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