1,721,084 research outputs found
A Combined Atmospheric Rivers and Geopotential Height Analysis for the Detection of High Streamflow Event Probability Occurrence in UK and Germany
Full text linkThe role of atmospheric rivers (ARs) in inducing High Streamflow Events (HSEs) in Europe has been confirmed
by numerous studies. Here, we assume as HSEs the streamflows exceeding the 99th percentile of daily flowrate
time series measured at streamflow gauges.
Among the indicators of ARs are: the Integrated Water Vapor (IWV) and Integrated Water Vapor Transport (IVT).
For both indicators the literature suggests thresholds in order to identify ARs. Furthermore, local thresholds of
such indices are used to assess the occurrence of HSEs in a given region.
Recent research on ARs still leaves room for open issues: 1) The literature is not unanimous in defining which of the
two indicators is better. 2) The selection of the thresholds is based on subjective assessments. 3) The predictability
of HSEs at the local scale associated with these indices seems to be weak and to exist only in the winter months.
In order to address these issues, we propose an original methodology: (i) to choose between the two indicators
which one is the most suitable for HSEs predictions; (ii) to select IWT and/or IVT (IVT/IWV) local thresholds
in a more objective way; (iii) to implement an algorithm able to determine whether a IVT/IWV configuration is
inducing HSEs, regardless of the season. In pursuing this goal, besides IWV and IVT fields, we introduce as further
predictor the geopotential height at 850 hPa (GPH850) field, that implicitly contains information about the pattern
of temperature, direction and intensity of the winds. In fact, the introduction of the GPH850 would help to improve
the assessment of the occurrence of HSEs throughout the year. It is also plausible to hypothesize, that IVT/IWV
local thresholds could vary in dependence of the GPH850 configuration.
In this study, we propose a model to statistically relate these predictors, IVT/IWV and GPH850, to the simultaneous
occurrence of HSEs in one or more streamflow gauges in UK and Germany. Historical data from 57 streamflow
gauges in UK and 61 streamflow gauges in Germany, as well as reanalysis data of the 850 hPa geopotential fields
bounded from 90W to 70E and from 20N to 80N are used. The common period is 1960 to 2012. The link between
GPH850 and HSEs, and more precisely, the identification of the GPH850 states potentially able to generate HSEs
is performed by a combined Kohonen Networks (Self Organized Map, SOM) and Event Syncronization approach.
Complex network and modularity methods are used to cluster streamflow gauges that share common GPH850
configurations. Then a model based on a conditional Poisson distribution is carried out, in which the parameter of
the Poisson distribution is assumed to be a nonlinear function of GPH850 state and IVT/ IWV. This model allows
for the identification of the threshold of IVT/IWV beyond which there is the HSE highest probabilit
21st Century Projections of High Streamflow Events in the UK and Germany
Full text linkRadiative effects of anthropogenic changes in atmospheric composition are expected to enhance the hydrological
cycle leading to more frequent and intense floods. To explore if there will be an increased risk of river flooding
in the future, 21st century projections under global warming scenarios of High Streamflow Events (HSEs) for UK
and German rivers are carried out, using a model that statistically relates large-scale atmospheric predictors - 850
hPa Geopotential Height (GPH850) and Integrated Water Vapor Transport (IVT) - to the occurrence of HSEs in
one or simultaneously in several streamflow gauges. Here, HSE is defined as the streamflow exceeding the 99th
percentile of daily flowrate time series measured at streamflow gauges.
For the common period 1960-2012, historical data from 57 streamflow gauges in UK and 61 streamflow gauges in
Germany, as well as, reanalysis data of GPH850 and IVT fields, bounded from 90W to 70E and from 20N to 80N
are used.
The link between GPH850 configurations and HSEs, and more precisely, identification of the GPH850 states
potentially able to generate HSEs, is performed by a combined Kohonen Networks (Self Organized Map, SOM)
and Event Syncronization approach. Complex network and modularity methods are used to cluster streamflow
gauges that share common GPH850 configurations. Then a model based on a conditional Poisson distribution, in
which the parameter of the Poisson distribution is assumed to be a nonlinear function of GPH850 and IVT, allows
for the identification of GPH850 state and threshold of IVT beyond which there is the HSE highest probability.
Using that model, projections of 21st century changes in frequency of HSEs occurrence in UK and Germany are
estimated using the simulated fields of GPH850 and IVT from selected GCMs belonging to the Coupled Model
Inter-comparison Project Phase 5 (CMIP5). Among the different GCMs, those are selected whose retrospective
predictor fields have consistent statistics with the corresponding reanalysis data
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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
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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