1,721,368 research outputs found
Land tenure, and its influence upon streamflow regimes in Zimbabwe
No full textThere is limited information concerning the effects of traditional land use upon hydrologic regimes in southern Africa, or in the dry tropics. Significant information is presented regarding the legacy of inequitable land distribution and inappropriate colonial and settler land use policies upon hydrologic regimes and water availability in Zimbabwe.The influence of land tenure and land use upon regional variation in streamflow annual yields, flood magnitudes and storm flow volumes, base flow volumes and low flow characteristics is examined utilising a data base of 110 gauged dambo catchments in central Zimbabwe. At a catchment scale the streamflow regimes of nine basins of contrasting land use and land tenure, representative of various precipitation regimes and basin soil complexes in Zimbabwe are examined using standard probability distributions. Particular attention is paid to determining the effect of land tenure upon streamflow volumes and variability, flood frequency using both the annual maximum and partial duration series, dry season flow characteristics, and streamflow drought regimes using both fixed and practical threshold levels.Regionally, land tenure is an indiscriminate factor in describing catchment hydrologic response. There is some evidence to suggest that communal basins exhibit lower evapotranspiration losses than commercial estates. In association with shallow less permeable dambo soil complexes communal basins tend to enhance dry season flows. At a basin scale clear differences are presented between basins within similar soil complexes in all aspects of hydrologic regime, and are explained in terms of basin physiographic and land use characteristics. Land tenure at a basin scale appears to dominate hydrologic response through differing basin evapotranspiration rates and water management characteristics.As Zimbabwe is undergoing widespread land use change through agricultural resettlement, the results have important implications for the understanding of basin hydrologic response and basin water management.</p
An investigation of stoichiometery and thermo-mechanical processing parameters of (Pb,Bi)2Sr2Ca2Cu3Ox superconducting tapes
No full textThis thesis details an investigation into some of the processing parameters associated with the production of (Pb,Bi)-2223 tapes. Both monocore and multifilamentary (Pb, Bi)-2223 silver-sheathed superconducting tapes have been processed and characterised. The relative conversion of (Pb, Bi)-2212 to (Pb, Bi)-2223 has been measured using X-ray diffraction. The critical current density and the associated magnetic field dependence have also been measured. The parameters investigated include the stoichometery of the precursor powder, the mechanical deformation of multifilamentary tapes, the effect of the cooling rate, and the effect of twisting a multifilamentary tape.Two precursor powders were compared. The Endo composition powder ((Pb0.34Bi1.84)Sr1.91Ca2.03Cu3.06Ox) and a second powder, that had an additional 10% excess of (Pb,Bi)-2212 added to the Endo composition ((Pb0.374, Bi2.024)Sr2.101Ca2.133Cu3.266Oy). Both the Endo and 10% excess precursor powders were packed into thin, and thick silver sheaths, and a silver alloy (Ag(99.5%), Ni(0.2%), Mg(0.28%)). Of the three separate studies the thick silver sheath samples produced the best results for both precursor powders. The Endo composition tapes had better characteristics than the 10% excess tapes, with an Ic of 17 A and 14 A, respectively.The mechanical deformation experienced by 37 filament multifilamentary tapes before thermal processing was studied. The final wire diameter, the rolling steps used to convert the wire to a tape were investigated. It was found that tapes with thin, high aspect rotation filaments produced a higher critical current density. High aspect ration filaments were produced within the conductor using small rolling steps of 20 μm followed by one or two 100 μm steps to the as-rolled thickness. Through attempting to optimise both the diameter and the rolling regime a 20% improvement in the Jc was obtained from 12 KAcm-2 to 14.5 KAcm-2.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
- …
