1,720,989 research outputs found
Fluid-mediated, brittle-viscous deformation cycles at the brittle-ductile transition
No full textCrustal deformation at the brittle-ductile transition may take place by a combination of competing brittle fracturing and viscous flow processes. This competition may be triggered by variations of properties (e.g., T, P, density) of the fluid hosted by the fault at the time of deformation. Hence, a joint (micro)structural and geochemical approach to the study of the deformation processes and of the assisting fluid phase(s) provides insights into the dynamic evolution of strength in the seismogenic crust. Fault zones in the Olkiluoto nuclear waste disposal site in SW Finland exhibit a mixed brittle-ductile deformation style, and represent excellent targets to study coexisting ductile and brittle deformation in quartz-rich systems. We present results from a fault zone characterized by complex kinematics and reactivation history, as demonstrated by at least two types of synkinematic quartz-chlorite veins (types 1 and 2). Microstructural analysis documents a variety of fully ductile quartz deformation features (WEB’s, bulging and subgrain rotation recrystallization) overprinting and overprinted by mixed brittle-ductile textures (recrystallized cataclasites and healed fractures). Fluid inclusion microthermometry and chlorite geothermometry constrain deformation within the fault to 250-350°C, which is the typical T range defining the greenschist facies metamorphism at the base of the seismogenic crust. We propose that the repeated rheological switches from frictional to viscous deformation mechanisms were controlled by transient and repeated changes of fluid properties. If these variations took place at seismic velocities, the exhumed microstructural record would witness seismic cycles, with type 1 and type 2 veins reflecting discrete failure events during the shocks. The brittle-ductile deformation microstructures would represent instead the interseismic creep
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
Switching deformation mode and mechanisms during subduction of continental crust: a case study from Alpine Corsica
Full text linkThe switching in deformation mode (from distributed to localized) and mechanism (viscous versus frictional)
represent a relevant issue in the frame of processes of crustal deformation in turn connected with the concept of the
brittle-“ductile” transition and seismogenesis. On the other hand the role of brittle precursors in nucleating crystal-
plastic shear zones has received more and more consideration being now recognized as having a fundamental
role in the localization of deformation and shear zone development, thus representing a case in which switching
deformation mode and mechanisms interact and relate to each other. This contribution analyses an example of a
crystal plastic shear zone localized by brittle precursor formed within a host granitic-mylonite during deformation
in subduction-related environment
Strength of Dry and Wet Quartz in the Low-Temperature Plasticity Regime: Insights From Nanoindentation
Full text linkAt low-temperature and high-stress conditions, quartz deformation is controlled by the kinetics of dislocation glide, that is, low-temperature plasticity (LTP). To investigate the relationship between intracrystalline H2O content and the yield strength of quartz LTP, we have integrated spherical and Berkovich nanoindentation tests at room temperature on natural quartz with electron backscatter diffraction and secondary-ion mass spectrometry measurements of intracrystalline H2O content. Dry (<20 wt ppm H2O) and wet (20–100 wt ppm H2O) crystals exhibit comparable indentation hardness. Quartz yield strength, which is proportional to indentation hardness, seems to be unaffected by the intracrystalline H2O content when deformed under room temperature, high-stress conditions. Pre-indentation intracrystalline microstructure may have provided a high density of dislocation sources, influencing the first increments of low-temperature plastic strains. Our results have implications for fault strength at the frictional-viscous transition and during transient deformation by LTP, such as seismogenic loading and post-seismic creep
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
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