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Application of the transient storage model to analyze advective hyporheic exchange with deep and shallow sediment beds
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Hyporheic Flows in Stratified Beds
No full textSurface-subsurface exchange fluxes are receiving increasing interest because of their
importance in the fate of contaminants, nutrients, and other ecologically relevant
substances in a variety of aquatic systems. Solutions have previously been developed
for pore water flows induced by geometrical irregularities such as bed forms for the cases
of homogeneous sediment beds and idealized heterogeneous beds, but these solutions
have not accounted for the fact that streambed sediments are subject to sorting processes
that often produce well-defined subsurface structures. Sediments at the streambed
surface are often coarser than the underlying material because of size-selective sediment
transport, producing relatively thin armor layers. Episodic erosional and depositional
processes also create thick layers of different composition within the porous medium,
forming stratified beds. A series of experiments were conducted to observe conservative
solute transport in armored and stratified beds. An analytical solution was developed
for advective exchange with stratified beds and provides appropriate scaling of the
physical variables that control exchange flows. The results show that armor layers are too
thin to significantly alter the advective pumping process but provide significant solute
storage at short time scales. Stratified beds with layers of significant thickness favor
development of horizontal flow paths within the bed and change the rate of solute transfer
across the stream-subsurface interface compared to homogeneous beds
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
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