17,382 research outputs found
Bondi-Sachs Energy-Momentum for the CMC Initial Value Problem
The constraints on the asymptotic behavior of the conformal factor and
conformal extrinsic curvature imposed by the initial value equations of general
relativity on constant mean extrinsic curvature (CMC) hypersurfaces are
analyzed in detail. We derive explicit formulas for the Bondi-Sachs energy and
momentum in terms of coefficients of asymptotic expansions on CMC hypersurfaces
near future null infinity. Precise numerical results for the Bondi-Sachs
energy, momentum, and angular momentum are used to interpret physically
Bowen-York solutions of the initial value equations on conformally flat CMC
hypersurfaces of the type obtained earlier by Buchman et al. [Phys. Rev. D
80:084024 (2009)].Comment: version to be published in Phys. Rev.
Biogeography of Wood-Boring Crustaceans (Isopoda: Limnoriidae) Established in European Coastal Waters
Marine wood-borers of the Limnoriidae cause great destruction to wooden structures exposed in the marine environment. In this study we collated occurrence data obtained from field surveys, spanning over a period of 10 years, and from an extensive literature review. We aimed to determine which wood-boring limnoriid species are established in European coastal waters; to map their past and recent distribution in Europe in order to infer species range extension or contraction; to determine species environmental requirements using climatic envelopes. Of the six species of wood-boring Limnoria previously reported occurring in Europe, only Limnoria lignorum, L. quadripunctata and L. tripunctata are established in European coastal waters. L. carinata and L. tuberculata have uncertain established status, whereas L. borealis is not established in European waters. The species with the widest distribution in Europe is Limnoria lignorum, which is also the most tolerant species to a range of salinities. L. quadripunctata and L. tripunctata appear to be stenohaline. However, the present study shows that both L. quadripunctata and L. tripunctata are more widespread in Europe than previous reports suggested. Both species have been found occurring in Europe since they were described, and their increased distribution is probably the results of a range expansion. On the other hand L. lignorum appears to be retreating poleward with ocean warming. In certain areas (e.g. southern England, and southern Portugal), limnoriids appear to be very abundant and their activity is rivalling that of teredinids. Therefore, it is important to monitor the distribution and destructive activity of these organisms in Europe
Arlis/ANZ 2.0
We've all been hearing about Web 2.0 and Library 2.0 lately. But just what are they all about, and is there anything there that Arlis/ANZ can take advantage of in order to better go about its business? Can there, should there, be an Arlis/ANZ 2.0? Arlis/ANZ, the Arts Libraries Society of Australia and New Zealand, is preparing to review it's online prescence. The Arlis/ANZ website is now three years old, and has been well maintained during that time. However it has not yet been systematically reviewed in terms of content, functionality, and strategic direction. The Arlis/ANZ Website version 'One' will be redeveloped into Arlis/ANZ Website version 'Two'. Although much of that review will concentrate on the structure, look and feel of the site, the review process offers an opportunity to incorporate Web 2.0 developments. By incorporating that 'best' of Web 2.0 in a strategic manner, Arlis/ANZ 2.0 - the website - has powerful potential to contribute toward the strength, cohesion and ongoing development of Arlis/ANZ 2.0 - the Society
Computation of the inverse Laplace Transform based on a Collocation method which uses only real values
We develop a numerical algorithm for inverting a Laplace transform (LT), based on Laguerre polynomial series expansion of the
inverse function under the assumption that the LT is known on the real axis only. The method belongs to the class of Collocation
methods (C-methods), and is applicable when the LT function is regular at infinity. Difficulties associated with these problems are due
to their intrinsic ill-posedness. The main contribution of this paper is to provide computable estimates of truncation, discretization,
conditioning and roundoff errors introduced by numerical computations. Moreover, we introduce the pseudoaccuracy which will be
used by the numerical algorithm in order to provide uniform scaled accuracy of the computed approximation for any x with respect
to ex . These estimates are then employed to dynamically truncate the series expansion. In other words, the number of the terms of
the series acts like the regularization parameter which provides the trade-off between errors.
With the aim to validate the reliability and usability of the algorithm experiments were carried out on several test functions
Quasipolynomial size frege proofs of Frankl's Theorem on the trace of sets
We extend results of Bonet, Buss and Pitassi on Bondy's Theorem and of Nozaki, Arai and Arai on Bollobas' Theorem by proving that Frankl's Theorem on the trace of sets has quasipolynomial size Frege proofs. For constant values of the parameter t, we prove that Frankl's Theorem has polynomial size AC(0)-Frege proofs from instances of the pigeonhole principle.Peer ReviewedPostprint (author's final draft
Slepton Non-Universality in the Flavor-Effective MSSM
Supersymmetric theories supplemented by an underlying flavor-symmetry
provide a rich playground for model building aimed at
explaining the flavor structure of the Standard Model. In the case where
supersymmetry breaking is mediated by gravity, the soft-breaking Lagrangian
typically exhibits large tree-level flavor violating effects, even if it stems
from an ultraviolet flavor-conserving origin. Building on previous work, we
continue our phenomenological analysis of these models with a particular
emphasis on leptonic flavor observables. We consider three representative
models which aim to explain the flavor structure of the lepton sector, with
symmetry groups , and .Comment: References added, minor typos corrected. 28 pages, 8 figure
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