1,720,961 research outputs found
Monitoring the fluvial palynomorph load in a lowland temperate catchment and its relationship to suspended sediment and discharge
Get PDFDespite it being a component of the seston we know very little about fluvial (waterborne) pollen and spore (palynomorph) transport. This paper presents the results of a monitoring programme conducted over two years and at a catchment scale in South West England. A hierarchical monitoring network was established with flood peak samples taken at 9 sub-catchments, intra-hydrograph samples taken in two sub-catchments and time-integrated sampling undertaken at one location. In addition sampling was undertaken of probable palynomorph sources such as channel bed and bank sediments, and the airborne pollen flux was monitored using modified Tauber traps. The results support previous research in illustrating how the vast majority of fluvial pollen and spores are transported during floods (91%) and that the main control on waterborne palynomorph assemblages is the catchment vegetation and its spatial distribution but with a long-distance (extra-catchment) component. However, strong seasonal effects are also shown, and the importance of distinctive sources such as the riparian input, bed re-suspension and overland flow into drains and tributaries is revealed. Fine sediment in river pools appears to act as a selective store of damaged cereal type pollen grains derived from arable fields. Although pollen does form part of composite particles the data presented here suggest that the majority of the pollen is transported as single grains. Fluvial palynomorph loading is strongly dependant upon discharge and so concentrations in laminated or varved sediments could be regarded as a proxy for flood magnitude
Monitoring fluvial pollen transport, its relationship to catchment vegetation and implications for palaeoenvironmental studies
Get PDFDespite being the most important source of pollen and spore input into most lakes and near-shore marine sediments, we know very little about fluvial (waterborne) pollen and spore transport. This paper presents the results of a dedicated monitoring programme conducted over 2 years and at a catchment scale in South West England. The land use of the nine sub-catchments monitored was determined using Landsat Thematic Data. At two stations, pollen and spore sampling through storm hydrographs was undertaken whilst at the other 7 sub-catchments only peak flow samples were collected. Samples were also collected from re-suspended bed material, riverbanks and at low flows. Airborne pollen flux was monitored using modified Tauber traps. The results support previous research illustrating how the vast majority of fluvial pollen and spores are transported during floods (in this case 91%) and that the main control on waterborne pollen and spore assemblages is the catchment vegetation. However, strong seasonal effects are shown as well as the importance of distinctive sources, such as the riparian input, bed re-suspension and overland flow into drains and tributaries. Fine sediment in river pools appears to act as a selective store of damaged cereal-type pollen grains in arable catchments and this can reduce the inherent underestimate of arable land from pollen diagrams with a high fluvial input and increase the visibility of early agriculture. In order to simulate the likely result of a flood-dominated influx to a small lake scenario, modelling was undertaken whereby different sub-catchments were substituted in order to represent changes in catchment vegetation under a constant hydrological regime. The results show the dampened response of land use groups to catchment land use change, and the frequent occurrence of anomalous single-level peaks due to seasonal flushes from specific near-stream vegetation types. Both these features are commonly seen in lake pollen diagrams. Fluvial pollen and spore loading is dependant upon discharge and so concentrations in laminated or varved sediments could be regarded as a proxy for flood magnitude. The implications for this study on the interpretation of lake and near-shore marine pollen and spore diagrams are discussed and it is argued that a more quantitative approach to waterborne pollen could improve the estimation of land use from lakes in the temperate zone
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
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