4,364 research outputs found

    On the fine structure of medium energy electron fluxes in the auroral zone and related effects in the ionospheric D-region

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    This study is based on measurements of trapped and precipitated electrons of energy &gt;30 keV and &gt;100 keV observed by polar orbiting environmental satellites during overpasses of the imaging riometer at Kilpisjärvi, Finland. The satellites are in sun-synchronous orbits of about 850 km altitude, recording the electron fluxes at 2-s time resolution. The riometer measures the radiowave absorption at 38.2 MHz, showing the spatial pattern within a 240 km field of view. <br><br> The analysis has focussed on two areas. Having found a close correlation between the radiowave absorption and the medium-energy electron fluxes during satellite overpasses, empirical relationships are derived, enabling one quantity to be predicted from the other for three sectors of local time. It is shown that small-scale variations observed during a pass are essentially spatial rather than temporal. <br><br> Other properties, such as the spectra and the relation between precipitated and trapped components, are also considered in the light of the theory of pitch angle scattering by VLF waves. It is found that the properties and behaviour depend strongly on the time of day. In the noon sector, the precipitated and trapped fluxes are highly correlated through a square law relationship

    Small carbon chains in circumstellar envelopes

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    Observations were made for a number of carbon-rich circumstellar envelopes using the Phoenix spectrograph on the Gemini South telescope to determine the abundance of small carbon chain molecules. Vibration-rotation lines of the ν3\nu_{3} antisymmetric stretch of C3_{3} near 2040 cm1^{-1} (4.902 μ\mum) have been used to determine the column density for four carbon-rich circumstellar envelopes: CRL 865, CRL 1922, CRL 2023 and IRC +10216. We additionally calculate the column density of C5_{5} for IRC +10216, and provide an upper limit for 5 more objects. An upper limit estimate for the C7_{7} column density is also provided for IRC+10216. A comparison of these column densities suggest a revision to current circumstellar chemical models may be needed

    The estimation of D-region electron densities from riometer data

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    International audienceAt high latitude the hard electron precipitation associated with auroral activity is a major source of ionization for the D-region, one consequence being the absorption of radio waves. Direct measurements of the D-region electron density are not readily available, however. This paper investigates the relationship between the electron density at altitudes between 100 and 70 km and the total radio absorption observed with a riometer, with a view to using the latter to predict the former. Tables are given of the median electron density corresponding to 1 dB absorption at 27.6 MHz for each hour of the day, and it is shown that at certain heights the estimates will be accurate to within a factor of 1.6 on 50% of the occasions. A systematic variation with time of day is probably associated with a progressive hardening of the typical electron spectrum during the morning hours. There is also evidence for a seasonal effect possibly due to seasonal variations of the mesosphere

    The measurement of household socio-economic position in tuberculosis prevalence surveys: a sensitivity analysis.

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    OBJECTIVE: To assess the robustness of socio-economic inequalities in tuberculosis (TB) prevalence surveys. DESIGN: Data were drawn from the TB prevalence survey conducted in Lusaka Province, Zambia, in 2005-2006. We compared TB socio-economic inequalities measured through an asset-based index (Index 0) using principal component analysis (PCA) with those observed using three alternative indices: Index 1 and Index 2 accounted respectively for the biases resulting from the inclusion of urban assets and food-related variables in Index 0. Index 3 was built using regression-based analysis instead of PCA to account for the effect of using a different assets weighting strategy. RESULTS: Household socio-economic position (SEP) was significantly associated with prevalent TB, regardless of the index used; however, the magnitude of inequalities did vary across indices. A strong association was found for Index 2, suggesting that the exclusion of food-related variables did not reduce the extent of association between SEP and prevalent TB. The weakest association was found for Index 1, indicating that the exclusion of urban assets did not lead to higher extent of TB inequalities. CONCLUSION: TB socio-economic inequalities seem to be robust to the choice of SEP indicator. The epidemiological meaning of the different extent of TB inequalities is unclear. Further studies are needed to confirm our conclusions

    Intervention Mapping: Physical Activity with Socially Disadvantaged Women - ePoster

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    Introduction Socially disadvantaged women (SDW) have lower levels of physical activity (PA), health inequalities and poorer health outcomes. These are associated with social determinants of health, e.g. Socioeconomic position and ethnic minority. Developing effective behaviour change programmes for SDW is complex due to disparities such as limited income and/or culturally inappropriate settings. These intricacies are often overlooked in PA policy. Consequently, interventions aimed at SDW often fail to show adequate reach, adoption and/or maintenance of PA. Therefore, we aim to inform policy and practice by developing needs-led PA interventions with SDW using Intervention Mapping (IM). IM begins with a needs assessment and follows an iterative six step process for planning interventions. Method Needs assessment tasks involved regular researcher participation in local PA sessions with SDW. The researcher also conducted 17 semi-structured interviews with SDW and community PA practitioners on the topic of PA. This data was thematically analysed and used within the first step of IM: to create a logic model of the PA health problem. Results Data gathered from interviews shows PA variety and suitable opportunities in Leeds and surrounding areas are lacking for SDW. These insights have demonstrated that the needs of SDW are essential to inform IM, PA policy and practice. Conclusion IM begins with a needs-led approach when tackling the health problem of inactivity for SDW. IM will continue to be used to design a comprehensive tool for practice and inform PA policy for SDW

    Improved Searches for HI in Three Dwarf Spheroidal Galaxies

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    Previous searches for HI in our Galaxy's dwarf spheroidal companions have not been complete enough to settle the question of whether or not these galaxies have HI, especially in their outer parts. We present VLA observations of three dwarf spheroidals: Fornax, Leo II, and Draco, all of which have known stellar velocities. The new data show no HI emission or absorption. Column density limits in emission are 4--7 x 10^18 atoms/cm^2 in the centers of the galaxies. The importance of the new observations is that they cover larger areas than previous searches and they are less plagued by confusion with foreground (Galactic) HI. The apparent absence of neutral gas in the Fornax dwarf spheroidal is especially puzzling because recent photometry shows evidence of stars only 10^8 years old. We discuss whether the VLA observations could have missed significant amounts of HI.Comment: 20 pages, 7 figures; to appear in the Astronomical Journa

    Establishing Social Work Practices in England: The Early Evidence

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    Social Work Practices (SWPs) were established in England in 2009 to deliver social work services to looked after children and care leavers. The introduction of independent social work-led organisations generated controversy focused on issues such as the privatisation of children's services and social workers' conditions of employment. This paper reports early findings from the evaluation of four of these pilots, drawing on interviews with children and young people, staff, and local authority and national stakeholders. The SWPs assumed a variety of organisational forms. The procurement process was demanding, with protracted negotiations over matters such as budgetary control and providing a round-the-clock service. Start-up was facilitated by an established relationship between the SWP provider and the local authority. Once operational, SWPs continued to rely on local authorities for various functions; in most cases, local authorities retained control of placement budgets. Levels of consultation and choice offered to children and young people regarding the move to an SWP varied considerably. Children's understanding about SWPs was generally low except in the pilot where most children retained their original social worker. These early findings show some dilution of the original SWP model, while the pilots' diversity allows the benefits of particular models to emerge

    Creating year 7 bubbles to support primary to secondary school transition: a positive pandemic outcome?

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    In this paper, we explore the benefits of new forms of in-school grouping for children moving from primary to secondary school during the COVID-19 pandemic in England. Our three-phase study with over 400 students and teachers found that protective measures to limit COVID-19 though year group ‘bubbles’ generated an environment more aligned to children’s previous primary school experience. This natural experiment smoothed the process of transition by providing a better correspondence with students’ developmental needs, especially for those on the cusp of adolescence. We recommend that physical, administrative and pedagogical school structures are reimagined for this age group to this end
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