1,721,298 research outputs found
The charging of composites in the space environment
Full text linkThesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1997.Includes bibliographical references (v.2, leaves 268-273).by Steven Andrew Czepiela.M.S
The impact of mesoscale jet activity on plankton heterogeneity and primary production : a numerical modelling study
No full textThis thesis presents a study of the effect of a developing instability of an open ocean mesoscale jet on the local ecosystem. Previous observational and modelling studies of the physical characteristics of open ocean frontal jets show large vertical velocities. These can have consequences for the plankton community through both the upwelling of nutrients and the redistribution of biota in the water column. A coupled numerical physical ecosystem model is developed to investigate the effect of the dynamics of a frontal jet on the ecosystem.The evolution of the instability of a mesoscale jet is found to give rise to both the vertical transport of nutrients into the euphotic zone and subduction of biota out of the euphotic zone. The upwelling of nutrients stimulates increases in primary production, with resulting increases in phytoplankton stocks. The increase in primary production can be locally of the order of 100%, and of the order of 10% when averaged over the frontal region. Biota subducted from the surface waters forms remnant populations of plankton below the euphotic zone destined for depletion. The action of upwelling and subduction introduces spatial heterogeneity in the plankton biomass and primary production at a variety of length scales. The length scales are of the order of a few kilometres for thin filaments and up to 50 km for coherent features.The major reaction of the ecosystem is through the formation of coherent physical structures that act to transfer water parcels across the frontal jet and vertically along sloping isopycnals. The formation of the coherent features is found to be very dependent on the stratification associated with the front. It is suggested that the gradient in isopycnal thickness across the jet can play a large role in whether coherent features form and in determining the magnitude of cross frontal transport.With increases in primary production occurring over several degrees of latitude and mostly resulting from increases in new production, frontal dynamics may make a significant contribution to the strength of the biological pump. Also with the relatively small scale of frontal features, these dynamic regions for the ecosystem are not able to be resolved in biogeochemical or climate models. With the aim of relating the effect of the frontal dynamics on the ecosystem to properties of the larger scale fields, a parameterisation of tracer fluxes is tested, based on the diffusion of isopycnal thickness. The evolution of along front average quantities is found to be well represented in the parameterisation model runs, and for the oligotrophic conditions at Bermuda in the summer months, the parameterised runs can also reproduce the increases in new production by considering vertical fluxes of a passive nitrate tracer.</p
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
