1,720,967 research outputs found
Phase diagram of the ST2 model of water
No full textWe evaluate the free energy of the fluid and crystal phases for the ST2 potential with reaction field corrections for the long-range interactions. We estimate the phase coexistence boundaries in the temperature–pressure plane, as well as the gas–liquid critical point and gas–liquid coexistence conditions. Our study frames the location of the previously identified liquid–liquid critical point relative to the crystalline phase boundaries, and opens the way for exploring crystal nucleation in a model where the metastable liquid–liquid critical point is computationally accessible
Potential energy landscape of the apparent first-order phase transition between low-density and high-density amorphous ice
Full text linkThe potential energy landscape (PEL) formalism is a valuable approach
within statistical mechanics to describe supercooled liquids and
glasses. Here we use the PEL formalism and computer simulations to study
the pressure-induced transformations between low-density amorphous ice
(LDA) and highdensity amorphous ice (HDA) at different temperatures. We
employ the ST2 water model for which the LDA-HDA transformations are
remarkably sharp, similar to what is observed in experiments, and
reminiscent of a first-order phase transition. Our results are
consistent with the view that LDA and HDA configurations are associated
with two distinct regions (megabasins) of the PEL that are separated by
a potential energy barrier. At higher temperature, we find that
low-density liquid (LDL) configurations are located in the same
megabasin as LDA, and that high-density liquid (HDL) configurations are
located in the same megabasin as HDA. We show that the pressure-induced
LDL-HDL and LDA-HDA transformations occur along paths that interconnect
these two megabasins, but that the path followed by the liquid is
different from the path followed by the amorphous solid. At higher
pressure, we also study the liquid-to-ice-VII first-order phase
transition, and find that the behavior of the PEL properties across this
transition is qualitatively similar to the changes found during the
LDA-HDA transformation. This similarity supports the interpretation that
the LDA-HDA transformation is a first-order phase transition between
out-of-equilibrium states. Finally, we compare the PEL properties
explored during the LDA-HDA transformations in ST2 water with those
reported previously for SPC/E water, for which the LDA-HDA
transformations are rather smooth. This comparison illuminates the
previous work showing that, at accessible computer times scales, a
liquid-liquid phase transition occurs in the case of ST2 water, but not
for SPC/E water. Published by AIP Publishing
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
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