1,721,137 research outputs found
Embolism propagation in Adiantum leaves and a biomimetic system
No full text<p><span>Drought poses a significant threat to forest survival worldwide by potentially </span><span>generating air bubbles that obstruct sap transport within plants’ hydraulic </span><span>systems. However, the detailed mechanism of air entry and propagation at </span><span>the scale of the veins remains elusive. Building up on a biomimetic model of </span><span>leaf which we developed, we propose a direct comparison of the air embolism </span><span>propagation in</span> <span>Adiantum</span> <span>(maidenhair fern) leaves, presented in Brodribb</span> <span>et al. </span><span>(PNAS 2016, Ref. [1]) and in our biomimetic leaves. In particular, we evidence </span><span>that the jerky dynamics of the embolism propagation observed in</span> <span>Adiantum </span><span>leaves can be recovered via the introduction of micrometric constrictions in </span><span>the section of our biomimetic veins, mimicking the nanopores present in the </span><span>bordered pit membranes in real leaves. We show that the intermittency in </span><span>the propagation can be retrieved by a simple model coupling the variations </span><span>of pressure induced by the constrictions and the variations of the volume of </span><span>the compliant microchannels. Our study marks a step with the design of a </span><span>biomimetic leaf that reproduces particular aspects of embolism propagation </span><span>in real leaves, utilizing a minimal set of controllable and readily tunable </span><span>components. This biomimetic leaf constitutes a promising physical analog and </span><span>sets the stage for future enhancements to fully embody the unique physical </span><span>features of embolizing real leaves.</span></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
Foam flow in an inhomogeneous confined media
No full textNous présentons une étude expérimentale de l’écoulement d’une mousse 2D (une monocouche de bulles) confinée dans une cellule de Hele-Shaw. Le milieu modélise une fracture ouverte rendue inhomogène par la présence d’un défaut local réduisant ou augmentant l’écartement de la cellule. Ce défaut fait varier la perméabilité du milieu et perturbe l’écoulement. Le suivi des bulles par transparence de la cellule permet alors la mesure des champs moyens de vitesse et de déformation, ainsi que la répartition des événements plastiques. Ces champs sont ensuite analysés en fonction des différents paramètres de contrôle du milieu, de l’écoulement, du défaut et de la mousse, que nous avons fait varier extensivement dans de nombreuses expériences. Nous retrouvons la forte asymétrie amont-aval caractéristique des écoulements de fluides viscoélastiques en présence d’un obstacle plein, et confirmons son origine élastique (contrôlée par la fraction liquide de la mousse). Nous montrons une forte corrélation linéaire des profils longitudinaux de vitesse et de déformation dans les régions loin en amont (lorsque la mousse se charge élastiquement) et en aval (lorsqu’elle relaxe) de l’obstacle plein ou partiel. Nous mettons également en évidence l’importance de la friction contre les plaques pour des confinements ou débits forts, faisant émerger des sillages positifs, à la suite d’une expansion locale, couplés à une orientation des bulles orthogonale à l’écoulement, ou encore des distorsions particulières de bulles. Par ailleurs, nous quantifions la perméabilité du défaut en fonction de l’écartement, en étudiant le rapport de la vitesse dans le défaut et de la vitesse moyenne dans la cellule loin du défaut. Nous examinons enfin, dans une étude indépendante, la dynamique de l’interface d’un fluide simple confiné, entrant et sortant d’un obstacle local partiel, en mettant en évidence une hystérésis lors de cycles d’imbibition et de drainage.We present an experimental study of a 2D foam, composed of a single monolayer of bubbles, forced to flow in a confining Hele-Shaw cell, which models an open fracture. A defect localized in the center of the cell, increasing or decreasing locally its gap, strongly disturbs the foam flow. The transparency of the cell allows to directly observe and monitor the bubbles’ motion and deformation. We therefore performed a systematic study of the average bubble velocity and deformation fields, as well as the spatial distribution of the bubble rearrangements, as a function of the control parameters of the experiments: the imposed driving velocity, the cell and defect geometry (gap and height), as well as the bubble size and liquid foam fraction (controlling the foam rheology). For a localized constriction, we observe a strong fore-aft asymmetry of the velocity field, with an extended region downstream, where the foam velocity is much larger than the imposed driving one. We confirm here the elastic origin of such "overshoot" » or "negative-wake", typical of viscoelastic fluid flows around an obstacle. We also show a linear correlation between longitudinal profiles of velocity and deformation in the regions far from the obstacle, both upstream (where the foam is loaded elastically) and downstream (where it relaxes). We furthermore show the importance of the friction against the wall plates for strong confinement and/or flow rates, leading to positive wakes after a local increase of the gap cell, coupled with a transversal orientation of the bubbles, as well as to strong unusual bubbles distortions. In addition, we quantify the defect permeability, by computing the evolution of the bubble velocity within the defect as a function of its height. Finally, in a complementary study, within an international collaboration, we have investigated the interfacial dynamics of a simple fluid, forced to flow through a local partial obstacle in a confining cell. We show that the two-phase interface displacements are strongly affected by the imposed flow rate, leading to asymmetric imbibition–drainage hysteresis cycles
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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