1,721,002 research outputs found
Scaling regimes and fluctuations of observables in computer glasses approaching the unjamming transition
Full text linkUnder decompression, disordered solids undergo an unjamming transition where
they become under-coordinated and lose their structural rigidity. The
mechanical and vibrational properties of these materials have been an object of
theoretical, numerical, and experimental research for decades. In the study of
low-coordination solids, understanding the behavior and physical interpretation
of observables that diverge near the transition is of particular importance.
Several such quantities are length scales ( or ) that characterize the
size of excitations, the decay of spatial correlations, the response to
perturbations, or the effect of physical constraints in the boundary or bulk of
the material. Additionally, the spatial and sample-to-sample fluctuations of
macroscopic observables such as contact statistics or elastic moduli diverge
approaching unjamming. Here, we discuss important connections between all of
these quantities, and present numerical results that characterize the scaling
properties of sample-to-sample contact and shear modulus fluctuations in
ensembles of low-coordination disordered sphere packings and spring networks.
Overall, we highlight three distinct scaling regimes and two crossovers in the
disorder quantifiers and as functions of system size
and proximity to unjamming . As we discuss, relates to the
standard deviation of the sample-to-sample distribution of the
quantity (e.g. excess coordination or shear modulus ) for
an ensemble of systems. Importantly, has been linked to
experimentally accessible quantities that pertain to sound attenuation and the
density of vibrational states in glasses.Comment: updated after peer revie
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
Ultrahigh Poisson's ratio glasses
Full text linkThe manner in which metallic glasses fail under external loading is known to
correlate well with those glasses' Poisson's ratio : low-
(compressible) glasses typically feature brittle failure patterns with scarce
plastic deformation, while high- (incompressible) glasses typically fail
in a ductile manner, accompanied by a high degree of plastic deformation and
extensive liquid-like flow. Since the technological utility of metallic glasses
depends on their ductility, materials scientists have been concerned with
fabricating high- glassy alloys. To shed light on the underlying
micromechanical origin of high- metallic glasses, we employ computer
simulations of a simple glass-forming model with a single tunable parameter
that controls the interparticle-potential's stiffness. We show that the
presented model gives rise to ultra high- glasses, reaching
and thus exceeding the most incompressible laboratory metallic glass. We
discuss the possible role of the so-called unjamming transition in controlling
the elasticity of ultra high- glasses. To this aim, we show that our
higher- computer glasses host relatively softer quasilocalized glassy
excitations, and establish relations between their associated characteristic
frequency, macroscopic elasticity, and mechanical disorder.Comment: 9 pages, 9 figure
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
Effects of coordination and stiffness scale-separation in disordered elastic networks
Full text linkMany fibrous materials are modeled as elastic networks featuring a
substantial separation between the stiffness scales that characterize different
microscopic deformation modes of the network's constituents. This scale
separation has been shown to give rise to emergent complexity in these systems'
linear and nonlinear mechanical response. Here we study numerically a simple
model featuring said stiffness scale-separation in two-dimensions and show that
its mechanical response is governed by the competition between the
characteristic stiffness of collective nonphononic soft modes of the stiff
subsystem, and the characteristic stiffness of the soft interactions. We
present and rationalize the behavior of the shear modulus of our complex
networks across the unjamming transition at which the stiff subsystem alone
loses its macroscopic mechanical rigidity. We further establish a relation in
the soft-interaction-dominated regime between the shear modulus, the
characteristic frequency of nonphononic vibrational modes, and the mesoscopic
correlation length that marks the crossover from a disorder-dominated response
to local mechanical perturbations in the near-field, to a linear,
continuum-like response in the far field. The effects of spatial dimension on
the observed scaling behavior are discussed, in addition to the interplay
between stiffness scales in strain-stiffened networks, which is relevant to
understanding the nonlinear mechanics of non-Brownian fibrous biomatter.Comment: 10 pages, 9 figures. v2: slightly modified analysis and additional
figur
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
- …
