1,721,270 research outputs found
Effects of microplastics on evaporation dynamics in porous media
No full textMicroplastics (MPs) pollution is an emerging threat to soil ecosystems. The present study aims to investigate the impacts of MPs on soil water evaporation dynamics and patterns. Two series of laboratory experiments were conducted using sand particles and clay mixed with different MPs to investigate how evaporation dynamics and patterns are influenced by the presence of MPs. Quartz sand including 0, 0.75, 1.5, and 4.5% of Polyethylene (PE) and Polyvinylchloride (PVC) were used to evaluate MPs effects on evaporation rates while bentonite mixed with sand and 0, 0.75, 1.5, 4.5, 6, 8, and 10% of PE and PVC were used to investigate evaporation-induced cracking patterns. The experiments were conducted under controlled laboratory conditions in a climate chamber at constant ambient temperature. Our results suggest that the addition of MPs led to more water evaporation compared to the samples without MPs. Microscopic imaging and analysis enabled us to evaluate the possible MPs effects on the modification of soil characteristics and pore structure affecting the evaporation behavior. Moreover, although increasing MPs concentrations appeared to induce only minor effects on the crack morphology formed as a result of evaporation from the mixture of sand and bentonite, the type of MPs (PE vs PVC) had more notable effects on the drying-induced cracking patterns. The reported experimental data and analysis extend our physical understanding of the parameters influencing soil water evaporation in the presence of MPs
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
Pore scale analyses of evaporation from porous media
No full textEvaporation from porous media is a key process in the hydrologic cycles, waste isolation, biological and food processes and other engineering application. Drying rate and patterns in porous media are strongly influenced by transport properties of the medium and the external evaporative demand. Drying rate from porous media often exhibit a transition from a nearly constant and high evaporation rate (stage 1) supplied by capillary liquid flow to a lower rate (stage 2) supplied by vapor diffusion. During stage 1, continuous liquid pathways connect the receding drying front with evaporating surface and sustain high evaporation rates. At a certain drying front depth, gravity overcomes capillary driving forces and a transition from liquid flow-supported stage-1 to diffusion-supported stage-2 evaporation occurs. The front depth at this transition marks a characteristic length defined by the width of pore size distribution. The extent and existence of hydraulic connections through the unsaturated zone above the drying front has been predicted theoretically and demonstrated experimentally using high resolution x-ray tomography and neutron radiography. In addition to provide detailed information regarding to the dynamics of drying front and water content distribution during evaporation, the concept of capillary characteristic length was extended to partially wettable porous media by systematically considering capillarity of clusters of hydrophilic and hydrophobic grains. Simplified geometrical and statistical assumptions have been applied to describe the porous media with mixed wettability. The theoretical predictions were successfully validated using a set of experiments with sands with different fraction of hydrophobic grains. Additionally, neutron radiography was used to investigate the drying of uniform hydrophilic and hydrophobic sand at high spatial and temporal resolutions to investigate the impact of wettability on drying front and water content dynamics. To explore the effect of liquid continuity and clarify the mass transport mechanisms supplying different stages of evaporation, the evaporation from porous media including hydrophobic sand layers was investigated. Results confirm interruption of capillary flow by hydrophobic layers and overall reduction in evaporative mass loss. Persistence of capillary flow to the interface between hydrophilic and hydrophobic layers was evident by accumulation of dye tracer indicating formation of vaporization plane. Evaporation flux across the hydrophobic layer was purely diffusive and proportional to the diffusion length to the surface (thickness of hydrophobic layer). In a further, theoretical and experimental studies were conducted to analyze evaporation behavior of layered porous media affected by the extent and sequence of layering and capillary characteristics of each layer (wettability, pore size distribution). The proposed model shows that the combination of intrinsic capillary characteristic length and the position of a layer below evaporation surface define the ultimate depth of drying front at the end of stage-1 evaporation. The model was tested in laboratory experiments using Hele-Shaw cells filled with layers of coarse and fine sand. Transition to stage-2 evaporation occurring at a depth defined by exceeding of the weakest "capillary link" in the sequence was confirmed. In addition to analyze the drying behavior of porous media under different conditions, a critical review was performed questioning the concept of enhanced water vapor fluxes from partially-saturated porous media relative to fluxes predicted based on Fick's law. This concept led to various mechanistic and phenomenological enhancement factors to reconcile apparent discrepancies between experiments and predictions made based on macroscopic diffusion theory. These concepts were reevaluated considering the role of capillary-induced liquid flow extending from saturated zone to vaporization plane. It was proved that the continuous capillary liquid flow is the main reason to measure experimentally fluxes more than the prediction by Fick's law of diffusion.LASE
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