11,800 research outputs found
Linear -positive sets and their polar subspaces
In this paper, we define a Banach SNL space to be a Banach space with a
certain kind of linear map from it into its dual, and we develop the theory of
linear -positive subsets of Banach SNL spaces with Banach SNL dual spaces.
We use this theory to give simplified proofs of some recent results of
Bauschke, Borwein, Wang and Yao, and also of the classical Brezis-Browder
theorem.Comment: 11 pages. Notational changes since version
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A verified and optimized Stream X-Machine testing method, with application to cloud service certification
The Stream X-Machine (SXM) testing method provides strong and repeatable guarantees of functional correctness, up to a specification. These qualities make the method attractive for software certification, especially in the domain of brokered cloud services, where arbitrage seeks to substitute functionally equivalent services from alternative providers. However, practical obstacles include: the difficulty in providing a correct specification, the translation of abstract paths into feasible concrete tests, and the large size of generated test suites. We describe a novel SXM verification and testing method, which automatically checks specifications for completeness and determinism, prior to generating complete test suites with full grounding information. Three optimisation steps achieve up to a ten-fold reduction in the size of the test suite, removing infeasible and redundant tests. The method is backed by a set of tools to validate and verify the SXM spec-ification, generate technology-agnostic test suites and ground these in SOAP, REST or rich-client service implementations. The method was initially validated using seven specifications, three cloud platforms and five grounding strategies
The Stellar Content Near the Galactic Center
High angular resolution J, H, K, and L' images are used to investigate the
stellar content within 6 arcsec of SgrA*. The data, which are complete to K ~
16, are the deepest multicolor observations of the region published to date.Comment: 34 pages, including 12 figure
Itinerant ferromagnetism in an atomic Fermi gas: Influence of population imbalance
We investigate ferromagnetic ordering in an itinerant ultracold atomic Fermi
gas with repulsive interactions and population imbalance. In a spatially
uniform system, we show that at zero temperature the transition to the
itinerant magnetic phase transforms from first to second order with increasing
population imbalance. Drawing on these results, we elucidate the phases present
in a trapped geometry, finding three characteristic types of behavior with
changing population imbalance. Finally, we outline the potential experimental
implications of the findings.Comment: 10 pages, 4 figures, typos added, references adde
Coming to America: Multiple Origins of New World Geckos
Geckos in the Western Hemisphere provide an excellent model to study faunal assembly at a continental scale. We generated a time-calibrated phylogeny, including exemplars of all New World gecko genera, to produce a biogeographic scenario for the New World geckos. Patterns of New World gecko origins are consistent with almost every biogeographic scenario utilized by a terrestrial vertebrate with different New World lineages showing evidence of vicariance, dispersal via temporary land bridge, overseas dispersal, or anthropogenic introductions. We also recovered a strong relationship between clade age and species diversity, with older New World lineages having more species than more recently arrived lineages. Our data provide the first phylogenetic hypothesis for all New World geckos and highlight the intricate origins and ongoing organization of continental faunas. The phylogenetic and biogeographical hypotheses presented here provide an historical framework to further pursue research on the diversification and assembly of the New World herpetofauna
Parametric correlations versus fidelity decay: the symmetry breaking case
We derive fidelity decay and parametric energy correlations for random matrix
ensembles where time--reversal invariance of the original Hamiltonian is broken
by the perturbation. Like in the case of a symmetry conserving perturbation a
simple relation between both quantities can be established.Comment: 8 pages, 8 figure
Transcytosis in MDCK cells: identification of glycoproteins transported bidirectionally between both plasma membrane domains.
MDCK cells display fluid-phase transcytosis in both directions across the cell. Transcytosis of cell surface molecules was estimated by electron microscopic analysis of streptavidin-gold-labeled frozen sections of biotinylated cells. Within 3 h, approximately 10% of the surface molecules, biotinylated on the starting membrane domain, were detected on the opposite surface domain irrespective of the direction of transcytosis. This suggests that the transcytosis rates for surface molecules are equal in both directions across the cell as shown previously for fluid-phase markers
Critical States in Disordered Superconducting Films
When subject to a pair-breaking perturbation, the pairing susceptibility of a
disordered superconductor exhibits substantial long-ranged mesoscopic
fluctuations. Focusing on a thin film subject to a parallel magnetic field, it
is proposed that the quantum phase transition to the bulk superconducting
condensate may be preempted by the formation of a glass-like phase with
multi-fractal correlations of a complex order parameter. Although not
universal, we argue that such behavior may be a common feature of quantum
critical phenomena in disordered environments.Comment: 7 pages, 1 eps figur
Reification and Truthmaking Patterns
Reification is a standard technique in conceptual modeling, which consists of including in the domain of discourse entities that may otherwise be hidden or implicit. However, deciding what should be rei- fied is not always easy. Recent work on formal ontology offers us a simple answer: put in the domain of discourse those entities that are responsible for the (alleged) truth of our propositions. These are called truthmakers. Re-visiting previous work, we propose in this paper a systematic analysis of truthmaking patterns for properties and relations based on the ontolog- ical nature of their truthmakers. Truthmaking patterns will be presented as generalization of reification patterns, accounting for the fact that, in some cases, we do not reify a property or a relationship directly, but we rather reify its truthmakers
Geodetic, teleseismic, and strong motion constraints on slip from recent southern Peru subduction zone earthquakes
We use seismic and geodetic data both jointly and separately to constrain coseismic slip from the 12 November 1996 M_w 7.7 and 23 June 2001 M_w 8.5 southern Peru subduction zone earthquakes, as well as two large aftershocks following the 2001 earthquake on 26 June and 7 July 2001. We use all available data in our inversions: GPS, interferometric synthetic aperture radar (InSAR) from the ERS-1, ERS-2, JERS, and RADARSAT-1 satellites, and seismic data from teleseismic and strong motion stations. Our two-dimensional slip models derived from only teleseismic body waves from South American subduction zone earthquakes with M_w > 7.5 do not reliably predict available geodetic data. In particular, we find significant differences in the distribution of slip for the 2001 earthquake from models that use only seismic (teleseismic and two strong motion stations) or geodetic (InSAR and GPS) data. The differences might be related to postseismic deformation or, more likely, the different sensitivities of the teleseismic and geodetic data to coseismic rupture properties. The earthquakes studied here follow the pattern of earthquake directivity along the coast of western South America, north of 5°S, earthquakes rupture to the north; south of about 12°S, directivity is southerly; and in between, earthquakes are bilateral. The predicted deformation at the Arequipa GPS station from the seismic-only slip model for the 7 July 2001 aftershock is not consistent with significant preseismic motion
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