10,998 research outputs found

    Complexity plots

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    In this paper, we present a novel visualization technique for assisting in observation and analysis of algorithmic\ud complexity. In comparison with conventional line graphs, this new technique is not sensitive to the units of\ud measurement, allowing multivariate data series of different physical qualities (e.g., time, space and energy) to be juxtaposed together conveniently and consistently. It supports multivariate visualization as well as uncertainty visualization. It enables users to focus on algorithm categorization by complexity classes, while reducing visual impact caused by constants and algorithmic components that are insignificant to complexity analysis. It provides an effective means for observing the algorithmic complexity of programs with a mixture of algorithms and blackbox software through visualization. Through two case studies, we demonstrate the effectiveness of complexity plots in complexity analysis in research, education and application

    The Bristol and Bath Railway Path: an ecopoetic sound collaboration

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    An ecopoetic sound piece produced in response to the Bristol and Bath Railway Path, UK

    The A–Z of Social Justice Physical Education: Part 1

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    Education professionals are morally compelled to ensure that all students feel accepted, safe, and are represented in their classes. Physical education is no different, however, specific practitioner orientated strategies to embark in more socially just practices are scarce in physical education literature. This paper provides the first part of an A-Z of social justice education series where practitioners are provided with examples of socially just physical education practices and ideas for use within classes. As an example, the letter A (Ability) unpacks the hyper-focus of physical education programs have placed on physical abilities and the need to be ability aware in all domains within the subject. Thus, it is essential that we prioritize a holistic and well-versed program for all students despite their abilities. Resources for each letter are provided where educators can find more information

    A Program of Photometric Measurements of Solar Irradiance Fluctuations from Ground-based Observations

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    Photometric observations of the sun have been carried out at the San Fernando Observatory since early 1985. Since 1986, observations have been obtained at two wavelengths in order to separately measure the contributions of sunspots and bright facular to solar irradiance variations. Researchers believe that the contributions of sunspots can be measured to an accuracy of about plus or minus 30 ppm. The effect of faculae is much less certain, with uncertainties in the range of plus or minus 300 ppm. The larger uncertainty for faculae reflects both the greater difficulty in measuring the facular area, due to their lower contrast compared to sunspots, and the greater uncertainty in their contrast variation with viewing angle on the solar disk. Recent results from two separate photometric telescopes will be compared with bolometric observations from the active cavity radiometer irradiance monitor (ACRIM) that was on board the Solar Max satellite

    Researching Bradford: A review of social research on Bradford District

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    A synthesis of findings from social research on the District of Bradford. This report synthesises the findings from a wide range of social research undertaken on the District of Bradford, primarily between 1995 and 2005. The researchers reviewed almost 200 pieces of work. The key results are summarised under thematic headings: - The social, economic and institutional context - Community cohesion - Housing, neighbourhoods and regeneration - Business and enterprise - Health, disability and social care - Children and young people - Education, skills and the labour market - Crime and community safety It also identifies a future research agenda. The main purpose of the review was to provide the Joseph Rowntree Foundation and local organisations in Bradford with a firm basis upon which to build future work in the District

    The A-Z of Social Justice Physical Education: Part 2

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    Education has the ability to both reproduce and transform broader social structures. Yet, teachers’ responsibilities are constantly increasing whilst budgets, resources, and staffing are depleted. We argue that we are living in a time of great uncertainty and precarity. As physical educators, we should make attempts to be socially conscious of this precarity and provide equitable environments for all students. This article (the second installment of a two-part series) is an attempt to make an important step in enacting a socially just and informed physical education program. In so doing, we highlight specific ways that teachers and teacher educators can prepare for and teach about precarity in physical education. By providing resources, readings, and examples from practice, we provide a framework that promotes ethics of value, care, and zeal for others

    Vanadium(V) oxo and imido calix[8]arene complexes: synthesis, structural studies, and ethylene homo/copolymerisation capability

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    Interaction of p-tert-butylcalix[8]areneH₈ (L⁸H₈) with in-situ generated [NaVO(Ot-Bu)₄] (from VOCl₃ and four equivalents of NaOtBu) afforded the dark brown complex [Na(NCMe)₅][(VO)₂L⁸H]·4MeCN (1·4MeCN), in which the calix[8]arene adopts a saddle-shaped conformation. Increasing (to four equivalents per L⁸) the amount of [NaVO(Ot-Bu)₄] present in the reaction, led to the formation of the yellow octa-vanadyl complex {[(Na(VO)₄L⁸)(Na(NCMe))₃] [Na(NCMe)₆}₂·10MeCN (2·10MeCN), in which the calix[8]arene adopts a pleated loop conformation. In the presence of adventitious oxygen, reaction of four equivalents of [VO(Ot-Bu)₃] (generated from VOCl₃ and 3KOtBu) with L⁸H₈ afforded the alkali-metal free green complex [(VO)₄L⁸(μ³-O)₂] (3); the solvates 3·3MeCN and 3·3CH₂Cl₂ have been isolated. In both solvates, the L⁸ ligand adopts a shallow saddle-shaped conformation, supporting a core comprising of a (VO)₄O₄ ladder. In the case of lithium, in order to obtain crystalline material, it was found necessary to reverse the order of addition such that lithium tert-butoxide was added to L⁸H₈, and then subsequently treated (at –78 ⁰C) with two equivalents of VOCl₃; crystallization from tetrahydrofuran (THF) afforded {(VO₂)₂Li₆[L⁸](thf)₂(OtBu)₂(Et₂O)₂}·Et₂O (4·Et₂O). In the structure of 4·Et₂O, vanadium, lithium and oxygen form a central lattern-type cage, which is capped top and bottom by an Li₂O₂2 diamond; the calix[8]arene is in a ‘down, down, out, out, down, down’ conformation. When the ‘same reaction’ was extracted into acetonitrile (MeCN), the salt complex [Li(NCMe)₄][(VO)₂L⁸H]·8MeCN (5.8MeCN) was formed. In 5·8MeCN, the [Li(NCMe)₄] cations reside between the anions in the clefts of L⁸H, the latter adopting a saddle-shaped conformation. Use of the imido precursors [V(Nt-Bu)(Ot-Bu)₃] and [V(Np-tolyl)(Ot-Bu)₃] and L⁸H₈, afforded, via an imido exchange, the salt [t-BuNH₃]{[V(p-tolylN)]₂L⁸H}·3½MeCN (6·3½MeCN). The molecular structures of 1 to 6 are reported; data collections for complexes 2·10MeCN, 3·3MeCN and 3·3CH₂Cl₂ required the use of synchrotron radiation. Complexes 1, 3 and 4 have been screened as pre-catalysts for the polymerization of ethylene in the presence of a variety of co-catalysts (with and without a re-activator) at various temperatures and for the co-polymerization of ethylene with propylene; results are compared versus the benchmark catalyst VO(OEt)Cl₂. In some cases, activities as high as 136,000 g/mmol.v.h were achievable, whilst it also proved possible to obtain higher molecular weight polymers (in comparible yields) versus the use of VO(OEt)Cl₂. In the case of the co-polymerization, the incorporation of propylene was 7.1 – 10.9 mol% (cf 10 mol% for VO(OEt)Cl₂), though catalytic activities were lower versus VO(OEt)Cl₂

    Baseline design of the filters for the LAD detector on board LOFT

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    The Large Observatory for X-ray Timing (LOFT) was one of the M3 missions selected for the phase A study in the ESA's Cosmic Vision program. LOFT is designed to perform high-time-resolution X-ray observations of black holes and neutron stars. The main instrument on the LOFT payload is the Large Area Detector (LAD), a collimated experiment with a nominal effective area of ~10 m 2 @ 8 keV, and a spectral resolution of ~240 eV in the energy band 2-30 keV. These performances are achieved covering a large collecting area with more than 2000 large-area Silicon Drift Detectors (SDDs) each one coupled to a collimator based on lead-glass micro-channel plates. In order to reduce the thermal load onto the detectors, which are open to Sky, and to protect them from out of band radiation, optical-thermal filter will be mounted in front of the SDDs. Different options have been considered for the LAD filters for best compromise between high quantum efficiency and high mechanical robustness. We present the baseline design of the optical-thermal filters, show the nominal performances, and present preliminary test results performed during the phase A study.Comment: Proc. SPIE 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, 91446
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