1,720,990 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Computationally efficient inversion of steady-state stochastic moment equations of groundwater flow
No full textThe impact of various sources of uncertainty on predictions of groundwater flow is conveniently tackled by casting the governing equations in a stochastic framework. Different inverse stochastic approaches have been developed to condition hydrogeological models’ predictions not only on direct measurements of parameters but also on information on state variables. Here, we focus on the inversion of stochastic moment equations of groundwater flow, as originally proposed by Hernandez et al. [2003, 2006]. In their approach, hydraulic conductivity is parameterized geostatistically based on measured values at discrete locations and unknown values at discrete pilot points. Prior estimates of pilot point values are obtained by generalized kriging. Posterior estimates at pilot points and (optionally) at measurement points are obtained by calibrating mean flow against measured values of head. The parameters are then projected onto a computational grid via kriging. Maximum likelihood calibration is employed to estimate not only hydraulic but also (optionally) unknown variogram parameters. The latter define the underlying geostatistical model. The approach yields covariance matrices for parameter estimation as well as head and flux prediction errors. The latter are obtained a posteriori by solving corresponding second-moment equations. Hernandez et al. [2003, 2006] implemented their inverse approach on a synthetic scenario, involving a general nonuniform flow condition in a bounded heterogeneous two-dimensional domain. Recently, Hendricks Franssen et al. [2009] performed a comparative synthetic study assessing the relative performance of this moment equations-based inverse method and several types of Monte Carlo inverse methodologies. Results of that study showed that that observed differences between the performances of the tested methods were not very large. However, Monte Carlo inversion of 100 realizations needed considerably more CPU time than geostatistical inversion of moment equations did. Bianchi-Janetti et al. [2009] applied the inverse moment-equations method to characterize the log-transmissivity distribution at a small scale field test site located in Montalto Uffugo (Italy). In their field application, information on hydraulic head is provided through self-potential signals recorded by a few surface electrodes during a pumping test, while only one transmissivity measurement was available.
Notwithstanding the theoretical and conceptual advantages of the method, the inversion of moment equations is still based on an optimization process which requires the numerical calculation of the derivatives of the objective function with respect to model parameters. These are in turn calculated from the derivatives of nodal heads (i.e., the sensitivity matrix). This limits its applicability to situations where the number of parameters, e.g., hydraulic conductivity values at pilot points, is not large because of the associated relevant computational cost. Here, we embed exact equations satisfied by the sensitivity matrix of the (ensemble) mean hydraulic head, up to its second-order of approximation, within the inverse modeling process. This renders the nonlinear inversion of stochastic moment equations feasible for a large number of unknown hydraulic parameters. We illustrate our algorithm and procedure with a synthetic example
Variations on the Author
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Contemporary Asian landscape. Photography as identity
Get PDFReferring to the important exhibition New Topographics (1975), William Jenkins wrote “the
pictures were stripped of any artistic frills and reduced to an essentially topographic state,
conveying substantial amounts of visual information but eschewing entirely the aspects of
beauty, emotion and opinion”. This transformation in photography reflects the deep and quick
changes that are happening in the world, focused on the urban transformation. Over half of
the world’s population now lives in cities and this change of lifestyles has led to a dramatic
transformation in the landscapes that surround us. Particularly from “New Topographics”
can be taken the idea of the use of photography like an urban narrative and descriptive tool.
The cities, in particular the Asiatic ones, are growing frenetically changing skyline and the
perception of the public space. Contemporary landscapes are changing: urbanization caused
a strong impact on the relationship between man and nature, and like the development of our
cities to follow specific urban planning, we try to control our human experience with nature.
These new developments are connected not only to the way that the physical landscape is
changing but, perhaps more importantly, to the way that we are dealing with these changing
environments. The new “documentary” photography reveals not only the impact of the man on
the landscape, but the way it occurs and contracts the interaction between the two. Through
a selection of eastern photographers that use the image as critical reading of contemporary
Asian landscape, this research highlights the role of photography as a needed document
to reflect on the extent of the landscape changes and the antithetical relationship between
permanence and change in urban and extra urban contexts
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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