505 research outputs found

    Uncertainty in Semantic Schema Integration

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    In this paper we present a new method of semantic schema integration, based on uncertain semantic mappings. The purpose of semantic schema integration is to produce a unified representation of multiple data sources. First, schema matching is performed to identify the semantic mappings between the schema objects. Then, an integrated schema is produced during the schema merging process based on the identified mappings. If all semantic mappings are known, schema merging can be performed (semi-)automatically

    The influence of cycloplegic in objective refraction

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    The purpose of this study was to compare refractions measured with an autorefractor and retinoscopy in cycloplegic and non-cycloplegic eyes. The objective refractions were performed in 199 right eyes from 199 healthy young adults with a mean age of 21.6 ±2.66 years. The measurements were performed first without cycloplegia and repeated 30 minutes later with cycloplegia. Data were analyzed using Fourier decomposition of the power profile. More negative values of component M and J0 were give by non-cycloplegic autorefraction compared to cycloplegic autorefraction (p<0.001). However more positive values were given by non-cycloplegic autorefraciton regarding to the J45 vector, althought this differences were not statistically significant (p=0.233). Regarding retinoscopy, more negative values of component M where obtained with non-cycloplegic retinoscopy (p<0.001); for the cylindrical vectors J0 and J45 the retinoscopy without cycloplegic yields more negative values (p= 0.234; p= 0.112, respectively). Accepting that differences between cycloplegic and non-cycloplegic retinoscopy are only due to accommodative response, present results confirm that when performed by an experienced clinician, retinoscopy is a more reliable method to obtain objective start point for refraction under non-cycloplegic conditions

    The Cow: Discovery of a Luminous, Hot, and Rapidly Evolving Transient

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    We present the ATLAS discovery and initial analysis of the first 18 days of the unusual transient event, ATLAS18qqn/AT2018cow. It is characterized by a high peak luminosity (~1.7 × 1044 erg s−1), rapidly evolving light curves (>5 mag rise to peak in ~3.5 days), and hot blackbody spectra, peaking at ~27,000 K that are relatively featureless and unchanging over the first two weeks. The bolometric light curve cannot be powered by radioactive decay under realistic assumptions. The detection of high-energy emission may suggest a central engine as the powering source. Using a magnetar model, we estimated an ejected mass of 0.1–0.4 M {}_{\odot }, which lies between that of low-energy core-collapse events and the kilonova, AT2017gfo. The spectra cooled rapidly from 27,000 to 15,000 K in just over two weeks but remained smooth and featureless. Broad and shallow emission lines appear after about 20 days, and we tentatively identify them as He i although they would be redshifted from their rest wavelengths. We rule out that there are any features in the spectra due to intermediate mass elements up to and including the Fe group. The presence of r-process elements cannot be ruled out. If these lines are due to He, then we suggest a low-mass star with residual He as a potential progenitor. Alternatively, models of magnetars formed in neutron star mergers, or accretion onto a central compact object, give plausible matches to the data

    The Role of Published Materials in Curriculum Development and Implementation for Secondary School Design and Technology in England and Wales

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    This is a postprint of an article whose final and definitive form has been published in the International Journal of Technology and Design Education. The original publication is available at www.springerlink.com.This paper discusses the ways in which teachers exploited a set of curriculum materials published as a vehicle for curriculum innovation, and the relationship between chosen modes of exploitation and teachers’ own perceptions of how the materials had ’added value’ to their teaching. The materials in question were developed by the Nuffield Design and Technology Project (’the Project’) to offer a pedagogy appropriate to the statutory curriculum for secondary school design and technology education in England and Wales (DFE/WO 1995). The Project had sought both to inform the statutory curriculum, and respond to its requirements. An earlier case study (Givens 1997) laid the foundations for the survey that is reported here. This paper focuses on the teaching of pupils aged 11–14. It finds that while most teachers made at least some use of all the various components of the publications, they were selective. While the Study Guide, which carries out a meta-cognitive dialogue with pupils, was generally underused, those teachers who did use it perceived greater value added by the materials as a whole to the quality of pupils’ work, their effectiveness in design and technology and their autonomy

    Synchronous online CPD: empirical support for the value of webinars in career settings

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    The careers profession in England is facing unprecedented challenges. Initiatives to improve service delivery while keeping costs low are attractive and online training holds the promise of high impact at low cost. The present study employs a qualitative methodology to evaluate a series of online ‘webinars’ conducted with 15 careers advisers. Results showed that the technology itself could impede learning, and participants missed out on the peer-to-peer interaction that takes place in a ‘bricks and mortar’ setting, but overall participants found that access to relevant, good quality training from the convenience of their workplace more than compensated for the challenges. The article offers conceptual support for the viability of online learning through the theory of equivalency, andragogy and transactional distance theory, and makes recommendations for practice

    Cultural and academic adjustment of refugee youth: Introduction to the special issue

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    © 2017 Elsevier Ltd In this introduction to the IJIR special issue on refugee youth in academic settings, the editors sought manuscripts that examined both challenges and effective practices in countries of temporary and permanent refugee resettlement. We welcomed diverse methodological approaches and empirical work at all levels and types of education (formal, non-formal, and informal). Our final selections do not fully represent the field of refugee education, as eight of the nine are studies in third countries of permanent resettlement, a designation received by only about one percent of the total refugee population. Perspectives came from the social sciences: psychology, sociology, anthropology, and sociolinguistic disciples. Themes of the articles fall into two broad categories: 1) educational challenges due to trauma, acculturation stressors, and educational issues; and 2) educational practices intended to address some of these challenges. Although the resettlement category is the smallest of the UNHCR's “durable solutions,” the authors present important findings to support refugee students’ success. These have to do with collaborative processes, issues of identity, the use of social media, and teacher training in multicultural and language support. In considering future work in this field, we conclude that dimensions of justice need to be more fully examined in other refugee solutions (such as repatriation and local integration in the first country of refuge). We recommend that more research be conducted on the current European “migrant crisis.” We also call for scholars to be public intellectuals in venues that can reframe the characterization of refugees in opposition to “fake news” fanning public fears

    Cultural and academic adjustment of refugee youth: Introduction to the special issue

    Get PDF
    © 2017 Elsevier Ltd In this introduction to the IJIR special issue on refugee youth in academic settings, the editors sought manuscripts that examined both challenges and effective practices in countries of temporary and permanent refugee resettlement. We welcomed diverse methodological approaches and empirical work at all levels and types of education (formal, non-formal, and informal). Our final selections do not fully represent the field of refugee education, as eight of the nine are studies in third countries of permanent resettlement, a designation received by only about one percent of the total refugee population. Perspectives came from the social sciences: psychology, sociology, anthropology, and sociolinguistic disciples. Themes of the articles fall into two broad categories: 1) educational challenges due to trauma, acculturation stressors, and educational issues; and 2) educational practices intended to address some of these challenges. Although the resettlement category is the smallest of the UNHCR's “durable solutions,” the authors present important findings to support refugee students’ success. These have to do with collaborative processes, issues of identity, the use of social media, and teacher training in multicultural and language support. In considering future work in this field, we conclude that dimensions of justice need to be more fully examined in other refugee solutions (such as repatriation and local integration in the first country of refuge). We recommend that more research be conducted on the current European “migrant crisis.” We also call for scholars to be public intellectuals in venues that can reframe the characterization of refugees in opposition to “fake news” fanning public fears

    Metabolic Rift or Metabolic Shift? Dialectics, Nature, and the World-Historical Method

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    Abstract In the flowering of Red-Green Thought over the past two decades, metabolic rift thinking is surely one of its most colorful varieties. The metabolic rift has captured the imagination of critical environmental scholars, becoming a shorthand for capitalism’s troubled relations in the web of life. This article pursues an entwined critique and reconstruction: of metabolic rift thinking and the possibilities for a post-Cartesian perspective on historical change, the world-ecology conversation. Far from dismissing metabolic rift thinking, my intention is to affirm its dialectical core. At stake is not merely the mode of explanation within environmental sociology. The impasse of metabolic rift thinking is suggestive of wider problems across the environmental social sciences, now confronted by a double challenge. One of course is the widespread—and reasonable—sense of urgency to evolve modes of thought appropriate to an era of deepening biospheric instability. The second is the widely recognized—but inadequately internalized—understanding that humans are part of nature

    Sensitivity of Chaos Measures in Detecting Stress in the Focusing Control Mechanism of the Short-Sighted Eye

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    yesWhen fixating on a stationary object, the power of the eye’s lens fluctuates. Studies have suggested that changes in these so-called microfluctuations in accommodation may be a factor in the onset and progression of short-sightedness. Like many physiological signals, the fluctuations in the power of the lens exhibit chaotic behaviour. A breakdown or reduction in chaos in physiological systems indicates stress to the system or pathology. The purpose of this study was to determine whether the chaos in fluctuations of the power of the lens changes with refractive error, i.e. how short-sighted a subject is, and/or accommodative demand, i.e. the effective distance of the object that is being viewed. Six emmetropes (EMMs, non-short-sighted), six early-onset myopes (EOMs, onset of short-sightedness before the age of 15), and six late-onset myopes (LOMs, onset of short-sightedness after the age of 15) took part in the study. Accommodative microfluctuations were measured at 22 Hz using an SRW-5000 autorefractor at accommodative demands of 1 D (dioptres), 2 D, and 3 D. Chaos theory analysis was used to determine the embedding lag, embedding dimension, limit of predictability, and Lyapunov exponent. Topological transitivity was also tested for. For comparison, the power spectrum and standard deviation were calculated for each time record. The EMMs had a statistically significant higher Lyapunov exponent than the LOMs ( 0.64±0.330.64±0.33 vs. 0.39±0.20 D/s0.39±0.20 D/s ) and a lower embedding dimension than the LOMs ( 3.28±0.463.28±0.46 vs. 3.67±0.493.67±0.49 ). There was insufficient evidence (non-significant p value) of a difference between EOMs and EMMs or EOMs and LOMs. The majority of time records were topologically transitive. There was insufficient evidence of accommodative demand having an effect. Power spectrum analysis and assessment of the standard deviation of the fluctuations failed to discern differences based on refractive error. Chaos differences in accommodation microfluctuations indicate that the control system for LOMs is under stress in comparison to EMMs. Chaos theory analysis is a more sensitive marker of changes in accommodation microfluctuations than traditional analysis methods
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