1,720,984 research outputs found
Dynamics of long term fluvial response in postglacial catchments of the Ladakh Batholith, Northwest Indian Himalaya
Full text linkUpland rivers control the large-scale topographic form of mountain belts, allow coupling of climate and tectonics at the earth’s surface and are responsible for large scale redistribution of sediment from source areas to sinks. However, the details of how these rivers behave when perturbed by changes to their boundary conditions are not well understood. I have used a combination of fieldwork, remotely sensed data, mathematical analysis and computer modelling to investigate the response of channels to well constrained changes in the forcings upon them, focussing in particular on the effects of glacial remoulding of the catchments draining the south flank of the Ladakh batholith, northwest Indian Himalaya. The last glacial maximum for these catchments is atypically old (~100 ka), and this allows investigation of the response to glaciation on a timescale not usually available. The geomorphology of the catchments is divided into three distinct domains on the basis of the behaviour of the trunk stream – an upper domain where the channel neither aggrades above or incises into the valley form previously carved by glacial abrasion, a middle domain where the channel incises a gorge down into glacial sediments which mantle the valley floor, and a lower domain where the channel aggrades above this postglacial sediment surface. This landscape provides a framework in which to analyze the processes and timescales of fluvial response to glacial modification. The dimensions of the gorge and the known dates of glacial retreat record a time averaged peak river incision rate of approximately 0.5 mm/y; the timescale for the river long profile to recover to a smooth, concave up form must exceed 1 Ma. These values are comparable with those from similarly sized catchments that have been transiently perturbed by changing tectonics, but have never been quoted for a glacially forced basin-scale response.
I have also demonstrated that lowering of the upper reaches of the Ladakh channel long profiles by glacial processes can systematically and nonlinearly perturb the slope-area (concavity) scaling of the channel downstream of the resulting profile convexities, or knickzones. The concavity values are elevated significantly above the expected equilibrium values of 0.3-0.6, with the magnitude controlled by the relative position of the knickzone within the catchment, and thus also by the degree of glacial modification of the fluvial system. This work also documents the existence of very similar trends in measured concavities downstream of long profile convexities in other transiently responding river systems in different tectonoclimatic settings, including those responding to changes in relative channel uplift. This previously unrecognised unity of response across a wide variety of different environments argues that such a trend is an intrinsic property of river response to perturbation. Importantly, it is consistent with the scaling expected from variation in incision efficiency driven by evolving sediment flux downstream of knickzones. The pervasive nature of this altered scaling, and its implications for fluvial erosion laws in perturbed settings, have significant consequences for efforts to interpret past changes in forcings acting on river systems from modern topography.
I follow this by examining in detail the channel hydraulics of the Ladakh streams as they incise in response to the glacial perturbation. I present a new framework under which the style of erosion of a natural channel can be characterized as either detachment- or transport-limited based upon comparison of the downstream distribution of shear stress with the resulting magnitude of incision. This framework also allows assessment of the importance of sediment flux driven effects in studied channels. This approach is then used to demonstrate that fluvial erosion and deposition in the Ladakh catchments is best modelled as a sediment flux dependent, thresholded, detachment-limited system. The exceptional quality of the incision record in this landscape enables an unprecedented calibration of the sediment flux function within this incision law for three different trunk streams. The resulting curves are not compatible with the theoretically-derived parabolic form of this relation, instead showing nonzero erosion rates at zero sediment flux, a rapid rise and peak at relative sediment fluxes of less than 0.5 and a quasi exponential decrease in erosional efficiency beyond this. The position of the erosional efficiency peak in relative sediment flux space and the magnitude of the curve are shown to be both variable between the catchments explored and also correlated with absolute sediment flux in the streams
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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