1,721,611 research outputs found
Ecosystem exploitation and trophodynamic indicators: a comparison between the Northern Adriatic Sea and Southern New England
Full text linkIn an ecosystem-based resource management context, it is crucial to assess the relationships between
community structure and ecosystem function and how those relationships change with resource extraction.
To elucidate how changes in resource use can affect community structure and ecosystem function,
we executed a comparative analysis of two different ecosystems subjected to notable fishing pressure.
We contrasted the Northern Adriatic Sea (NAS) and Southern New England (SNE) ecosystems by examining
outputs from comparable steady-state models. Both ecosystems have relatively high fishing pressure
and a high biomass of benthic invertebrates. The basic structure of the food webs shows
differences both in the number and definition of the functional groups, as described in the models. Fisheries,
on the contrary, show similarities both in terms of catches and discards. Almost all statistics summarizing
the structure and flows showed values three times higher in the SNE than in the NAS ecosystem,
but despite this difference the two ecosystems exhibited similar, overall properties. Biomass ratios and
the Mixed Trophic Impact (MTI) analysis showed that both ecosystems are dominated by the benthic
compartment. Removing the biomass effect, however, shows a clear top-down effect, with a high rank
achieved by fishing activities. In general terms, the low mean trophic level of catches and the high primary
production required (PPR) values result in a high overexploitation level of the ecosystem, as highlighted
by the L index. We conclude by exploring how comparative studies will continue to be valuable as
ecosystem-based management is further implemented
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
Simulations and interpretations of cumulative trophic theory
Full text linkExamining marine ecosystems in a distinct way can produce new ecological, theoretical and applied insights. The common “S” and “hockey stick” -shaped curves, which result from examining the cumulative biomass and trophic level and the cumulative production and cumulative biomass curves of marine ecosystems, have strong potential to elucidate the mechanisms of marine food webs. These curves are based on the cumulative trophic theory, which can be summarized as the integration of biomass and production across trophic level that results from the relatively simple trophic transfer equation. Here we test the behavior of this theory via modeled simulations of the transfer equation under a variety of common mechanisms that can influence marine ecosystems. The simulated scenarios we present and evaluate here explore bottom-up driven changes (production, growth), internal dynamics (transfer efficiency) or top-down driven changes (mortality, selectivity), as well as multi-mechanism scenarios (overfishing and eutrophication) that are commonly experienced in marine ecosystems. We explore these scenarios at high, medium or low levels of change for each feature to ascertain how they can result in major changes to the realized trophodynamics of a marine ecosystem. Our results lend credence to the generality of the cumulative trophic theory by predicting the empirically observed “S” and “hockey stick” -shaped curves under a wide range of possible mechanisms. Given that common, repeatable and predictable dynamics is a key hallmark of increasingly robust theories, the application of cumulative trophic theory in managing marine ecosystems enables more repeatable and predictable responses across a wide range of conditions
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
Biomass accumulation across trophic level: analysis of landings for the Mediterranean Sea
Full text linkThe need to implement Ecosystem-Based-Management (EBM) in marine ecosystems and the recent adoption of European Union directives, such as the Marine Strategy Framework Directive (MSFD), make indicators that are able to describe ecosystem state particularly relevant. The trophodynamic context is promising in that it can define integrative ecosystem indicators from modelling and field data. Here we analyze energy accumulation across trophic levels (TLs), i.e. the accumulation of energy in various biomass components of an ecosystem. The analysis of biomass accumulation across TLs, previously applied to surveys and model output data, was applied to a time series (1970 to 2010) of landings in the Mediterranean Sea and its 8 sub-areas. The standardized cumulative biomass versus TL curves for each year were fit to a logistic function, revealing that the accumulation pattern was detectable using landings data and confirming prior patterns. Parameters describing the curve shape, i.e. basal biomass, inflection point and steepness, were considered as possible indicators for assessing changes of ecosystem state through time. These parameters were able to detect systems modification in terms of both space and time and exhibited differential sensitivity to external drivers. The inflection point was mainly fishery-driven, whereas steepness seems to respond to environmental features, indicating an ability to discriminate across major ecosystem drivers. The application of Monte Carlo un certainty analysis showed that all of the parameters are sufficiently robust to possible sampling errors in the TL assignment to the different taxa. Collectively, these results confirm the robustness of patterns for cumulative biomass across TL curves seen in a growing number of marine eco systems. These emergent features suggest that this approach could produce useful ecosystem indicators for the implementation of EBM and the MSFD
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
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