1,720,955 research outputs found
Landslide Sediment Flux and Forest Management in Northeastern Vancouver Island, Coastal British Columbia
No full textTo evaluate landslide response of mountain drainage basins to forest management we examine a historical
inventory in northeastern Vancouver Island. The study area is underlain by extrusive (upper Triassic Karmutsen
Formation) and intrusive rocks (Jurassic Island Intrusions). The dataset, compiled via interpretation of sequential aerial photosets, helicopter traverses, and extensive fieldwork, comprises a total of 1961 sediment sources, including 798 field-measured events. Field- and photo-based data cover a time window of approximately 70
years. The effects of forest management on landslide activity are assessed in terms of landslide density, sediment
production, landslide geometry, landslide magnitude-frequency relations, topographic conditions of landslide initiation and deposition, and sediment redistribution across landscape components. Results indicate that forest management alters natural landslide dynamics in many respects. Logging-related debris avalanches are typically smaller. Consequently, the magnitude-frequency relation in logged terrain occupies the small-medium magnitude spectrum (< 6000 m3), with frequencies increasing by over an order of magnitude. Lithologic effects on sediment production appear amplified, in that terrain underlain by extrusive rocks become increasingly more unstable than intrusive ones. Analysis of landslide initiation and deposition zones reveals that forest management promotes colluvial aggradation on mid and lower hillslopes and in gullies. This pattern, which accelerates sediment recharge of gully systems, has the potential of increasing the frequency of channelized debris-flows, hence cause an extended period of disturbance, before sediment dynamics recover to pre-logging conditions. The effects of forest clearing on hillslope-channel coupling are composite: in cutblocks the percentage of sediment delivered to streams is reduced by 20-60% whereas road-related landslides are associated with highestconnectivity to streams
Colluvial sediment dynamics in mountain drainage basins
No full textColluvial sediment dynamics are examined using a 70-year landslide inventory in formerly glaciated
mountain drainage basins of coastal British Columbia, Canada. Landslide sediment transfer is documented by
identifying landslide types, and by characterizing preferential sites of landslide initiation, delivery, and
storage across spatial scales. Data analysis reveals that open-slope landslides delivering material to seasonal
or perennial channels and fluvial terraces are the dominant mechanisms of sediment transfer. This finding
suggests high instability of the low-order channel network and its ongoing re-organization (degradation)
after generalized sediment recharge occurred in the last glacial maximum. In the study period, landslide
activity across the landscape has generated net degradation on planar slopes and first-order colluvial
channels, whereas unchannelled valleys, higher-order colluvial channels and alluvial channels have
accumulated material. The scaling relation of the landslide sediment yield appears to be controlled by the
spatial arrangement of the relict glacial macro-forms. Landslide yield is highest in unchannelled topography,
decreases at the scale of channel initiation (Ad~0.002 km2), and remains constant for drainage areas where
length scales of cirque/valley walls and hanging valley floors overlap (0.002bAdb0.06). Injections of
landslide material start declining consistently beyond areas larger than 0.6 km2 (the scale of relict glacial
trough initiation), where fluvial environments become increasingly disconnected from landslide inputs.
Cumulative yield indicates that colluvial sediment redistribution is limited to small basins; specifically, 90% of
the colluvial load is released at scales smaller than about 0.6 km
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
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