1,720,961 research outputs found
Towards better integrators for dissipative particle dynamics simulations
Get PDFCoarse-grained models that preserve hydrodynamics provide a natural approach to study collective properties of soft-matter systems. Here, we demonstrate that commonly used integration schemes in dissipative particle dynamics give rise to pronounced artifacts in physical quantities such as the compressibility and the diffusion coefficient. We assess the quality of these integration schemes, including variants based on a recently suggested self-consistent approach, and examine their relative performance. Implications of integrator-induced effects are discussed
Integration schemes for dissipative particle dynamics simulations: From softly interacting systems towards hybrid models
No full textWe examine the performance of various commonly used integration schemes in dissipative particle dynamics simulations. We consider this issue using three different model systems, which characterize a variety of different conditions often studied in simulations. Specifically, we clarify the performance of integration schemes in hybrid models, which combine microscopic and mesoscale descriptions of different particles using both soft and hard interactions. We find that in all three model systems many commonly used integrators may give rise to surprisingly pronounced artifacts in physical observables such as the radial distribution function, the compressibility, and the tracer diffusion coefficient. The artifacts are found to be strongest in systems, where interparticle interactions are soft and predominated by random and dissipative forces, while in systems governed by conservative interactions the artifacts are weaker. Our results suggest that the quality of any integration scheme employed is crucial in all cases where the role of random and dissipative forces is important, including hybrid models where the solvent is described in terms of soft potentials. Regarding the integration schemes, the best overall performance is found for integrators in which the velocity dependence of dissipative forces is taken into account, and particularly good performance is found for an approach in which velocities and dissipative forces are determined self-consistently. Remaining temperature deviations from the desired limit can be corrected by carrying out the self-consistent integration in conjunction with an auxiliary thermostat, in a manner that is similar in spirit to the well-known Nose-Hoover thermostat. Further, we show that conservative interactions can play a significant role in describing the transport properties of simple fluids, in contrast to approximations often made in deriving analytical theories. In general, our results illustrate the main problems associated with simulation methods in which dissipative forces are velocity dependent, and point to the need to develop new techniques to resolve these issues. (C) 2002 American Institute of Physics.PT: J; CR: AHLRICHS P, 1999, J CHEM PHYS, V111, P8225 ALLEN MP, 1993, COMPUTER SIMULATION BESOLD G, 2000, PHYS REV E A, V62, R7611 BOON JP, 1980, MOL HYDRODYNAMICS DENOTTER WK, 2000, INT J MOD PHYS C, V11, P1179 DENOTTER WK, 2001, EUROPHYS LETT, V53, P426 DUNWEG B, 1991, INT J MOD PHYS C, V2, P817 DZWINEL W, 2000, INT J MOD PHYS C, V11, P1 DZWINEL W, 2000, J COLLOID INTERF SCI, V225, P179 ESPANOL P, 1995, EUROPHYS LETT, V30, P191 ESPANOL P, 1999, PHYS REV E, V59, P6340 ESPANOL P, 1999, PHYS REV LETT, V83, P4542 FLEKKOY EG, 1999, PHYS REV LETT, V83, P1775 FLEKKOY EG, 2000, PHYS REV E A, V62, P2140 FORREST BM, 1995, J CHEM PHYS, V102, P7256 FRENKEL D, 1996, UNDERSTANDING MOL SI GARDINER CW, 1983, HDB STOCHASTIC METHO GIBSON JB, 1999, INT J MOD PHYS C, V10, P241 GROOT RD, 1997, J CHEM PHYS, V107, P4423 GROOT RD, 1999, J CHEM PHYS, V110, P9739 HANSEN JP, 1986, THEORY SIMPLE LIQUID HOOGERBRUGGE PJ, 1992, EUROPHYS LETT, V19, P155 LADD AJC, 1993, PHYS REV LETT, V70, P1339 LADD AJC, 1994, J FLUID MECH, V271, P285 LADD AJC, 1994, J FLUID MECH, V271, P311 LECUYER P, 1988, COMMUN ACM, V31, P742 MALEVANETS A, 1999, J CHEM PHYS, V110, P8605 MALEVANETS A, 2000, EUROPHYS LETT, V52, P231 MALEVANETS A, 2000, J CHEM PHYS, V112, P7260 MARSH CA, 1997, EUROPHYS LETT, V38, P411 MARSH CA, 1997, PHYS REV E, V56, P1676 MARTYNA GJ, 1995, J CHEM PHYS, V102, P8071 MASTERS AJ, 1999, EUROPHYS LETT, V48, P1 MURAT M, 1998, J CHEM PHYS, V108, P4340 NIKUNEN P, UNPUB NOVIK KE, 1998, J CHEM PHYS, V109, P7667 PAGONABARRAGA I, 1998, EUROPHYS LETT, V42, P377 PRESS WH, 1972, NUMERICAL RECIPES FO, P271 SERRANO M, 2001, PHYS REV E 2, V64 SHELLEY JC, 2000, CURR OPIN COLLOID IN, V5, P101 SODDEMANN T, 2001, EUR PHYS J E, V6, P409 SPENLEY NA, 2000, EUROPHYS LETT, V49, P534 THIJSSEN JM, 1999, COMPUTATIONAL PHYSIC TUCKERMAN ME, 2000, J PHYS CHEM B, V104, P159 VATTULAINEN I, UNPUB VENTUROLI M, 1999, PHYS CHEM COMM, V10 VERLET L, 1967, PHYS REV, V159, P98 WARREN PB, 1998, CURR OPIN COLLOID IN, V3, P620; NR: 48; TC: 37; J9: J CHEM PHYS; PG: 13; GA: 525TLSource type: Electronic(1
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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