2,482 research outputs found
Interface relaxation in electrophoretic deposition of polymer chains: Effects of segmental dynamics, molecular weight, and field
Using different segmental dynamics and relaxation, characteristics of the
interface growth is examined in an electrophoretic deposition of polymer chains
on a three (2+1) dimensional discrete lattice with a Monte Carlo simulation.
Incorporation of faster modes such as crankshaft and reptation movements along
with the relatively slow kink-jump dynamics seems crucial in relaxing the
interface width. As the continuously released polymer chains are driven (via
segmental movements) and deposited, the interface width grows with the
number of time steps , (--,
which is followed by its saturation to a steady-state value . Stopping the
release of additional chains after saturation while continuing the segmental
movements relaxes the saturated width to an equilibrium value ().
Scaling of the relaxed interface width with the driving field , remains similar to that of the steady-state width. In
contrast to monotonic increase of the steady-state width , the relaxed
interface width is found to decay (possibly as a stretched exponential)
with the molecular weight.Comment: 5 pages, 7 figure
Genetic analysis of cognitive failures (CFQ); A study of Dutch adolescent twins and their parents
A substantial part of the inter-individual variation in everyday cognitive failures in memory, perception and motor control can be attributed to genetic factors. Cognitive failures were assessed with the Cognitive Failures Questionnaire (Broadbent, Cooper, FitzGerald and Parkes, 1982) in a large sample of Dutch adolescent twin pairs and their biological parents. The heritability for CFQ scores was around 50 per cent. There was no association between CFQ scores and age or educational level. Both in the parental generation (aged 46 years on average) and in the o€spring generation (aged 17.7 years on average) women had somewhat higher mean CFQ scores than men. There were no sex di€erences in heritabilities. The part of the variance that could not be attributed to genetic factors was best explained by environmental in¯uences unique to the individual. There was no evidence for the in¯uence of shared environment on CFQ scores. CFQ scores of husband and wife were correlated (r ˆ 0.22) and this association was modeled as phenotypic assortment. The correlations between parents and o€spring were somewhat lower than the correlations between dizygotic twins. Under a model with equal heritabilities in parents and o€spring, there was some evidence that the genetic factors that in¯uence cognitive failures in the two generations are partly di€erent. # 1998 John Wiley & Sons, Ltd
Looking backward: From Euler to Riemann
We survey the main ideas in the early history of the subjects on which
Riemann worked and that led to some of his most important discoveries. The
subjects discussed include the theory of functions of a complex variable,
elliptic and Abelian integrals, the hypergeometric series, the zeta function,
topology, differential geometry, integration, and the notion of space. We shall
see that among Riemann's predecessors in all these fields, one name occupies a
prominent place, this is Leonhard Euler. The final version of this paper will
appear in the book \emph{From Riemann to differential geometry and relativity}
(L. Ji, A. Papadopoulos and S. Yamada, ed.) Berlin: Springer, 2017
Physics in Riemann's mathematical papers
Riemann's mathematical papers contain many ideas that arise from physics, and
some of them are motivated by problems from physics. In fact, it is not easy to
separate Riemann's ideas in mathematics from those in physics. Furthermore,
Riemann's philosophical ideas are often in the background of his work on
science. The aim of this chapter is to give an overview of Riemann's
mathematical results based on physical reasoning or motivated by physics. We
also elaborate on the relation with philosophy. While we discuss some of
Riemann's philosophical points of view, we review some ideas on the same
subjects emitted by Riemann's predecessors, and in particular Greek
philosophers, mainly the pre-socratics and Aristotle. The final version of this
paper will appear in the book: From Riemann to differential geometry and
relativity (L. Ji, A. Papadopoulos and S. Yamada, ed.) Berlin: Springer, 2017
ZFITTER v.6.21 - A Semi-Analytical Program for Fermion Pair Production in e+e- Annihilation
We describe ZFITTER, a Fortran program based on a semi-analytical approach to
fermion pair production in e+e- annihilation at a wide range of centre-of-mass
energies, including the PETRA, TRISTAN, LEP1/SLC, and LEP2 energies. A flexible
treatment of complete O(alpha) QED corrections and of some higher order
contributions is made possible with three calculational chains containing
different realistic sets of restrictions in the photon phase space. Numerical
integrations are at most one-dimensional. Complete O(alpha) weak loop
corrections supplemented by selected higher-order terms may be included. The
program calculates Delta r, the Z width, differential cross-sections, total
cross-sections, integrated forward-backward asymmetries, left-right
asymmetries, and for tau pair production also final-state polarization effects.
Various interfaces allow fits to be performed with different sets of free
parameters.Comment: 200 pages, Latex2e, 26 figures, 4 tables; uses axodraw, epsfig, epsf,
graphicx, espcrc1; typos of v.1 corrected, version for subm. to Comp. Phys.
Commu
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