7,630 research outputs found
Reengineering the process of manufacturing thermal-cryogenics tanks
Includes bibliographical references
Model charged cylindrical nanopore in a colloidal dispersion: charge reversal, overcharging and double overcharging
Using the hypernetted-chain/mean spherical approximation (HNC/MSA) integral
equations we study the electrical double layer inside and outside a model
charged cylindrical vesicle (nanopore) immersed into a primitive model
macroions solution, so that the macroions are only present outside the
nanopore, i.e., the vesicle wall is impermeable only to the external macroions.
We calculate the ionic and local linear charge density profiles inside and
outside the vesicle, and find that the correlation between the inside and
outside ionic distributions causes the phenomena of overcharging (also referred
to as surface charge amplification) and/or charge reversal. This is the first
time overcharging is predicted in an electrical double layer of cylindrical
geometry. We also report the new phenomenon of double overcharging. The present
results can be of consequence for relevant systems in physical-chemistry,
energy storage and biology, e.g., nanofilters, capacitors and cell membranes.Comment: 10 pages, 4 figure
The radial plot in meta-analysis : approximations and applications
Fixed effects meta-analysis can be thought of as least squares analysis of the radial plot, the plot of standardized treatment effect against precision (reciprocal of the standard deviation) for the studies in a systematic review. For example, the least squares slope through the origin estimates the treatment effect, and a widely used test for publication bias is equivalent to testing the significance of the regression intercept. However, the usual theory assumes that the within-study variances are known, whereas in practice they are estimated. This leads to extra variability in the points of the radial plot which can lead to a marked distortion in inferences that are derived from these regression calculations. This is illustrated by a clinical trials example from the Cochrane database. We derive approximations to the sampling properties of the radial plot and suggest bias corrections to some of the commonly used methods of meta-analysis. A simulation study suggests that these bias corrections are effective in controlling levels of significance of tests and coverage of confidence intervals
Large Deviations for Random Power Moment Problem
We consider the set M_n of all n-truncated power moment sequences of
probability measures on [0,1]. We endow this set with the uniform probability.
Picking randomly a point in M_n, we show that the upper canonical measure
associated with this point satisfies a large deviation principle. Moderate
deviation are also studied completing earlier results on asymptotic normality
given by \citeauthorChKS93 [Ann. Probab. 21 (1993) 1295-1309]. Surprisingly,
our large deviations results allow us to compute explicitly the (n+1)th moment
range size of the set of all probability measures having the same n first
moments. The main tool to obtain these results is the representation of M_n on
canonical moments [see the book of \citeauthorDS97].Comment: Published by the Institute of Mathematical Statistics
(http://www.imstat.org) in the Annals of Probability
(http://www.imstat.org/aop/) at http://dx.doi.org/10.1214/00911790400000055
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