1,722,175 research outputs found

    Clemens, M.

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    Planches de l'article de Clemens M. M. Bayer

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    Planches de l'article de Clemens M. M. Bayer. In: Épigraphie et iconographie. [Actes du Colloque tenu à Poitiers, 5-8 octobre 1995] Poitiers : Centre d'études supérieures de civilisation médiévale, 1996. pp. 1-5. (Civilisation Médiévale, 2

    Computer-aided detection of cerebral aneurysms in angiographies

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    Magdeburg, Univ., Fak. für Informatik, Diss., 2013von Clemens M. Hentschk

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed

    Asteroid impact risk

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    Asteroid impacts are a hazard to human populations. A method to assess the impact risk of hazardous asteroids was developed in this work, making use of the universal concept of risk culminating in the Asteroid Risk Mitigation Optimization and Research (ARMOR) tool. Using this tool, the global spatial risk distribution of a threatening asteroid can be calculated and expressed in the units of expected casualties (= fatalities). Risk distribution knowledge enables disaster managers to plan for a potential asteroid impact through identification of high risk regions and estimation of total risk as a scalar value. Expressing the risk in terms of expected casualties would allow the placement of the asteroid threat on the same scale as other human hazards. Thus, this unit provides an accessible way of defining thresholds for asteroid threat response protocols, of communicating the threat utilizing a new hazard scale, and of allocating adequate resources to address the hazard by comparison with other natural disasters. To accomplish risk estimation, vulnerability models were needed that relate the severity of impact effects (wind blast, overpressure shock, thermal radiation, cratering, seismic shaking, ejecta out-throw, and tsunami) on the human population and a novel comprehensive suite of such models were derived and presented. The need for high fidelity impact effect and vulnerability modelling, as opposed to a simplified, impact location based approach, for risk estimation of a specific asteroid threat was analysed and confirmed. Subsequently, the method of ARMOR was applied to asteroid 2015 RN35 to produce an example risk distribution output. Additional analysis shows that the general impact location distribution of asteroids is approximately uniform, confirming, for the first time, a common assumption made in planetary defense. Extensive global simulations were performed utilizing an artificial sample of 50,000 impactors with sizes up to 400m to identify which impact effects are most hazardous to the human population. Aerothermal effects are most hazardous while tsunamis only contribute moderately to the overall hazard. The average land impactor is an order of magnitude more dangerous than a similar water impactor and asteroids smaller than 50-60m (density ≈ 3100 kg/m3) are expected to airburst rather than reach the surface. Furthermore, the average loss estimate for asteroid impactors enables fast threat analysis of newly discovered asteroids and helps determine the asteroid size that contributes most to the residual asteroid impact risk. These results provide new insights to inform efficient preparation for a future asteroid threat. In the future, ARMOR can be used to perform on-ground risk driven asteroid detection mission design which would reduce risk of an incoming asteroid progressively and this is not accomplished with current methods

    Variations on the Author

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    “Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship

    Appropriate Similarity Measures for Author Cocitation Analysis

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    We provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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