1,720,958 research outputs found
Exportação de nutrientes em plantações de eucalipto e de pinheiro
Full text linkMestrado em Engenharia do AmbienteAs perdas de azoto e fósforo totais, por escorrência e às escalas de parcela e bacia, foram estudadas durante o ano hidrológico 2011/12 em plantações de Eucalyptus globulus e Pinus pinaster em duas micro bacias pertencentes à bacia hidrográfica do rio Vouga (centro de Portugal). Durante o período de estudo, foram recolhidas e analisadas 64 amostras de escorrência superficial à escala de parcela (32 em pinhal e 32 em eucaliptal), e 122 amostras de escoamento nos ribeiros, 72 delas durante os picos de cheia. As determinações de azoto e fósforo totais foram realizadas por um método colorimétrico integrado num sistema por injeção em fluxo. Os resultados mostraram diferenças na exportação de nutrientes nos dois tipos de uso do solo, tanto à escala de bacia como à escala de parcela, estando claramente condicionadas pelas diferenças na geração de escorrência nos dois tipos de floresta. As estimativas de exportação de fósforo total para eucaliptal foram de 0,032 kg/ha·ano e de 0,063 kg/ha·ano para o pinhal. No entanto, para o azoto total as exportações foram mais elevadas com 0,467 kg/ha·ano para o eucaliptal e de 1,457 kg/ha·ano para o pinhal.Total nitrogen and phosphorus loses in surface runoff at plot scale and in total streamflow at catchment scale were studied during the hydrological year 2011/12 in Eucalyptus globulus and Pinus pinaster stands in two micro-catchments belonging to Vouga river basin (north-central Portugal). During the study period were collected and analyzed a total of 64 samples of surface runoff (32 in pine and 32 in eucalypt) and 122 total streamflow samples at catchment scale, 72 during the peak flow events. Total nitrogen and phosphorus determinations were done using a colorimetric method and integrated in a flow injection system. The results showed differences in nutrient exports from both land uses at plot and catchment scale that can be related to the differences in runoff and streamflow generation in both types of forest. The estimated total phosphorus exports were 0.032 kg/ha·year for eucalypt and 0.063 kg/ha·year for pine. Exports of total nitrogen were higher 0.467 kg/ha·year for eucalipt and 1.457 kg/ha·year for pine
Investigación dos procesos que regulan o caudal e a calidade das augas na bacía do río Anllóns
Full text linkAssessing the impacts of sustainable agricultural practices for water quality improvements in the Vouga catchment (Portugal) using the SWAT model
No full textThe extensive use of fertilizers has become one of themost challenging environmental issues in agricultural catchment
areas. In order to reduce the negative impacts fromagricultural activities and to accomplish the objectives of
the European Water Framework Directive we must consider the implementation of sustainable agricultural
practices. In this study, we assess sustainable agricultural practices based on reductions in N-fertilizer application
rates (from 100% to 0%) and N-applicationmethods (single, split and slow-release) across key agricultural land use
classes in the Vouga catchment, Portugal. The SWAT model was used to relate sustainable agricultural practices,
agricultural yields and N-NO3 water pollution deliveries. Results show that crop yields as well as N-NO3 exportation
rates decrease with reductions in N-application rates and single N-application methods lead to lower crop
yields and higher N-NO3 exportation rates as compared to split and slow-release N-application methods
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
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