1,720,966 research outputs found
Nucleation and growth of myrmekite during ductile shear deformation in metagranites
No full textMyrmekite is extensively developed along strain gradients of continuous, lower amphibolite facies shear
zones in metagranites of the Gran Paradiso unit (Western Alps). To evaluate the role of stress, strain
energy and fluid phase in the formation of myrmekite, we studied a sample suite consisting of weakly
deformed porphyric granites (WDGs), foliated granites (FGs) representative of intermediate strains, and
mylonitic granites (MGs). In the protolith, most K-feldspar is microcline with different sets of perthite
lamellae and fractures. In the WDGs, abundant quartz-oligoclase myrmekite developed inside Kfeldspar
only along preexisting perthite lamellae and fractures oriented at a high angle to the incremental
shortening direction. In the WDGs, stress played a direct role in the nucleation of myrmekites along
interfaces already characterized by high stored elastic strain because of lattice mismatch between Kfeldspar
and albite. In the FGs and MGs, K-feldspar was progressively dismembered along the growing
network of microshear zones exploiting the fine-grained recrystallized myrmekite and perthite
aggregates. This was accompanied by a more pervasive fluid influx into the reaction surfaces, and
myrmekite occurs more or less pervasively along all the differently oriented internal perthites and
fractures independently of the kinematic framework of the shear zone. In the MGs, myrmekite forms
complete rims along the outer boundary of the small K-feldspar porphyroclasts, which are almost
completely free of internal reaction interfaces. Therefore, we infer that the role of fluid in the nucleation
of myrmekite became increasingly important as deformation progressed and outweighed that of stress.
Mass balance calculations indicate that, in Al–Si-conservative conditions, myrmekite growth was
associated with a volume loss of 8.5%. This resulted in microporosity within myrmekite that enhanced
the diffusion of chemical components to the reaction sites and hence the further development of
myrmekite
Strain dependent variation of microstructure and texture in naturally deformed Carrara marble
No full textThis study investigates the microstructure and texture variations across a mm-scale shear zone in Carrara marble of the Alpi Apuane (Italy).
The microstructures have been investigated for grain size, texture, and shape fabrics. Textures have been measured with Computer-Integrated
Polarization Microscopy (CIP) and Electron Back Scattered Diffraction (EBSD) separating porphyroclast and recrystallized grains. The deformation,
which post-dates an earlier deformation phase and subsequent annealing, is strongly localized. The microstructures and textures change
across the shear strain gradient and are interpreted to preserve a time sequence of progressive stages of deformation. The bulk shear strain rate is
estimated to be about 1011 sec1 at deformation temperatures of approximately 325 C 30 C.
The protomylonite is characterized by a core mantle structure with a bimodal grain size distribution which changes gradually to a completely
dynamically recrystallized microstructure with a unimodal grain size distribution in the mylonitic center of the shear zone. Core-mantlestructures
are produced by dominant rotation recrystallization accompanied by some grain boundary migration. The microstructural transition
from protomylonite to mylonite coincides with a change in texture. With increasing strain the single c-axis maximum of an earlier inherited
texture in the protomylonite is replaced by a similar texture in a different orientation (maximum normal to the shear plane) which is consistent
with dominant basal hai and r h2201i slip. The microstructural and textural variations depend on the proportion of recrystallized grains. As
dynamic recrystallization progresses with finite strain the texture development is finite strain-dependent. The comparison of the microstructures
and textures to other natural and to experimental examples explains the progressive change of the texture and demonstrates the texture evolution
produced by dynamic recrystallization
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
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