1,720,983 research outputs found
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
A Target Fish Community to Guide River Restoration
No full textA method is proposed and demonstrated to specify a fish community to serve as a target for planning river restoration projects and as an endpoint for evaluating programme progress. Our target fish community is appropriate for small rivers in southern New England with basins characterized by dispersed human activities. Our study was part of a multi-agency improvement effort of the Quinebaug River in southern Massachusetts and northeast Connecticut, USA. We identify fish species expected to be found in streams, lakes, and river reaches of the Quinebaug River basin. An expected rank order of abundance was computed using fish surveys from rivers identified by restoration programme managers as being in a desirable condition for a human-dominated landscape. The rank order of species was converted to expected community proportions following a theoretical log–log relation between species abundances and occurrences in complex communities. Criteria from a committee of agency and water use representatives were influential in specifying a target community; so the overall method blends policy, objective zoogeography analyses, and theory-based parameters of community structure. We believe the use of a target community can be an important element in the design and evaluation of river restoration where the aim cannot be to copy pristine, natural ecosystem properties.Peer reviewe
Predicting ecological outcomes of stream creation using fish community attributes
No full textWe demonstrated an approach for predicting a new stream environment and the fishes it can support in terms of species composition, population density, and biomass. The challenge was to depict the future of a flowing stream in a setting where no present stream existed. The habitat of the Peconic River was field–surveyed and digitally mapped for three water–level conditions: run, glide and pool. Biomass estimates, in g/m2, were calculated for species historically found in the river, and species percent biomass was used to determine the number of each species likely to occur in each habitat type. The total biomass for all sites in each habitat type was averaged to predict biomass per unit area by habitat type. Biomass was then linked to habitat type to enable an estimate of where each fish species would be located and in what proportions. Biomass was predicted to increase with the amount of water in the Peconic River system. Pools are expected to exist with greater frequency at low and mid water and runs are expected to be more prevalent at high water. Glides are only expected when water levels are low. The total predicted biomass for the Peconic River study section in low water is expected to be 7 kg for glides, 13 kg for runs and 11 kg for pools. In mid water, 34 kg of biomass is expected for runs and 88 kg for pools. In high water, 370 kg of biomass is expected for runs and 62 kg for pools. Chain pickerel (Esox niger) is expected to comprise the highest biomass in all habitat types at all water levels. The results from this study are important to decision makers seeking a solution to an environmental problem through creation of a waterway in a heavily populated and altered environmental setting.Peer reviewe
Landscape scale assessment of stream channel and riparian habitat restoration needs
No full textHuman modifications of streams and rivers have caused extensive stream channel and riparian degradation. Cost-effective, rapid assessment tools can be used to better manage such areas by identifying the status of habitats for restoration planning and protection. We used a spatially explicit, reach-scale geographic information system modeling strategy to examine stream channel and riparian condition and prioritize restoration actions. The stream channel condition index uses information on land use, road and railroad density, and sinuosity. The riparian condition index uses calculations of percent forest, patch density, and convexity based on land cover in the floodplain. Reaches were classified into restoration categories based on stream channel and riparian condition model results, land ownership, slope, position in the subwatershed, and adjacency to high-quality habitat. We compared modeled restoration priority rankings with those in the management plan for the East Credit subwatershed in Ontario, Canada. Predicted stream channel restoration priority rankings matched field-based classifications for 86% of the reaches in the East Credit subwatershed. Predicted riparian restoration priority rankings matched field-based classifications for 81% of the reaches. Our methods replicate with fairly good accuracy the results obtained using intensive field surveys and stakeholder input. Managers can use these cost-effective strategy development tools to identify candidate reaches for further study and prioritize stream channel and riparian restoration actions over large regions.Peer reviewe
A GIS Framework for Fish Habitat Prediction at the River Basin Scale
No full textWe present a geographic information system (GIS) framework to classify stream habitats and provide fish distribution predictions comprehensively at the landscape scale. Stream segments were classified into one of eighteen habitat types using three landscape attributes: stream size (three categories), stream quality (three categories), and water quality (two categories). An extensive literature search was undertaken to classify fish species into the same eighteen habitat types based on preferences for the three landscape attributes. We tested our framework in 39 sites throughout the upper Allegheny River basin in western New York. No difference was detected between observed and predicted numbers of fish species among stream habitats. Further, field collected bankfull width measurements, stream quality ratings, and water quality sampling results were largely consistent with predicted values. The habitat type expected to have the greatest fish species richness was large streams or small rivers with intact stream quality and suitable water quality. Our framework is rapidly applied, comprehensive, inexpensive, and built on widely available data thereby offering an efficient alternative to traditional field-based efforts for regional habitat classification and fish distribution prediction
Modeling Aquatic Macroinvertebrate Richness Using Landscape Attributes
No full textWe used a rapid, repeatable, and inexpensive geographic information system (GIS) approach to predict aquatic macroinvertebrate family richness using the landscape attributes stream gradient, riparian forest cover, and water quality. Stream segments in the Allegheny River basin were classified into eight habitat classes using these three landscape attributes. Biological databases linking macroinvertebrate families with habitat classes were developed using life habits, feeding guilds, and water quality preferences and tolerances for each family. The biological databases provided a link between fauna and habitat enabling estimation of family composition in each habitat class and hence richness predictions for each stream segment. No difference was detected between field collected and modeled predictions of macroinvertebrate families in a paired t-test. Further, predicted stream gradient, riparian forest cover, and total phosphorus, total nitrogen, and suspended sediment classifications matched observed classifications much more often than by chance alone. High gradient streams with forested riparian zones and good water quality were predicted to have the greatest macroinvertebrate family richness and changes in water quality were predicted to have the greatest impact on richness. Our findings indicate that our model can provide meaningful landscape scale macroinvertebrate family richness predictions from widely available data for use in focusing conservation planning efforts.Peer reviewe
A Water Quality Model for Regional Stream Assessment and Conservation Strategy Development
No full textNonpoint-source (NPS) pollution remains the primary source of stream impairment in the United States. Many problems such as eutrophication, sedimentation, and hypoxia are linked with NPS pollution and reduced water quality for aquatic and terrestrial organisms. Increasingly, NPS pollution models have been used for landscape scale pollution assessment and conservation strategy development. Our modeling approach functions at a scale between simple landscape level assessments and complex, data intensive modeling by providing a rapid, landscape scale geographic information system (GIS) model with minimal data requirements and widespread applicability. Our model relies on curve numbers, literature-derived pollution concentrations, and land status to evaluate total phosphorus (TP), total nitrogen (TN) and suspended solids (SS) at the reach scale. Model testing in the Chesapeake Bay watershed indicated that predicted distributions of water quality classes were realistic at the reach scale but precise estimates of pollution concentrations at the local scale can have errors. Application of our model in the tributary watersheds along Lake Ontario suggested that it is useful to managers in watershed planning by rapidly providing important information about NPS pollution conditions in areas where large data gaps exist, comparisons among stream reaches across numerous watersheds are required, or regional assessments are sought.Peer reviewe
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