1,720,968 research outputs found
Sediment and nutrient export by water from an agricultural catchment: an analysis of hysteresis patterns in the upper Relau River, Penang
No full textA small drainage basin (0.5 km2) was selected on the Relau hill to evaluate sediment and nutrient export. Stream flow gauging, water depth and gulp water samples were collected manually on a weekly basis between November 2001 to October 2002 with additional gauging and water samples taken during storm events. The concentrations of sediment and nutrient were analysed to determine the quality of the river water and the health of the catchment. The highest suspended sediment concentrations and nutrients concentration in upper Relau catchment are, in most cases, associated with periods of high discharge during the monitoring period. Hysteresis relationships between SSC, NO3-N, TN, orthophosphate and TP concentration with discharge (Q) shows some form of pattern of variation during the monitoring period. The hysteresis approach was used to identify the sources of SSC, NO3-N and orthophosphate in streams. The findings from this study are common to most drainage systems having seasonal bimodal discharge. We describe the mechanisms of SSC, NO3-N and orthophosphate, TN and TP concentrations generation with discharge magnitudes, highlighting the importance of storm events in the transportation of pollutants from this small hill-land catchment where agriculture is the dominant land use
Water quality of streams and wells of north Perlis: a comparative analysis
No full textWater resources in catchment area came from various sources. Water from the surface infiltrate and leached down to the ground water. Land use activities on the surface will affect water quality of both surface and underground water. Underground water has been use by Malaysian as their water resources. Perlis and Kelantan are the two states in Malaysia that have a lot of wells still in use for water supply especially during dry season. This study investigates the spatial and temporal changes in water quality of surface and ground water of north Perlis from July 2001-December 2001. Results indicate that generally well water had lower physico-chemical values and nutrient content compared to stream water. A significant difference was observed for DO, pH, SRP and turbidity. The higher concentrations of calcium in wells reflecting the influence of geology on water quality. Nutrient contamination is minimal and the most probable source of water pollution is from agricultural runoff, fertilizers and domestic waste causing the water quality of north Perlis to degrade
Longitudinal variation of water quality in Sungai Jarum catchment - linking ecology with hydrology for reservoir management
No full textIn recent years, human activities, such as urbanization and agriculture, have been blamed for the degradation of water quality in many developing countries. Rivers draining agricultural land are susceptible to diffused or non-point source pollution. A study was conducted in Timah Tasoh catchment areas with the aim to investigate the effect of land use activities and eutrophication of the Timah Tasoh reservoir. A water quality monitoring programme was carried out from January 2001. This paper, however, focuses on the longitudinal variation of water quality parameters of Sungai Jarum as one of the two major water sources for the reservoir. The study was carried out from July to December 2001. Most physical parameters (temperature, dissolved oxygen, pH, conductivity, total dissolved solids, TDSturbidity) and nutrients varied between stations along the river. The general trend was that the water quality was getting better approaching the reservoir, where nutrient contents decreased longitudinally from its sources in the upper catchment to the reservoir. A reduction of almost 80% and 90% was observed for nitrogen and phosphorus, respectively at Tasoh, and a further reduction from Tasoh to the reservoir. Sedimentation and nutrient uptake by plant along the river corridor and in the littoral zones is the most probable cause for the reduction in nutrient contents and help maintaining good water quality of the reservoir
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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