23,579 research outputs found

    Relational semantics of linear logic and higher-order model-checking

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    In this article, we develop a new and somewhat unexpected connection between higher-order model-checking and linear logic. Our starting point is the observation that once embedded in the relational semantics of linear logic, the Church encoding of any higher-order recursion scheme (HORS) comes together with a dual Church encoding of an alternating tree automata (ATA) of the same signature. Moreover, the interaction between the relational interpretations of the HORS and of the ATA identifies the set of accepting states of the tree automaton against the infinite tree generated by the recursion scheme. We show how to extend this result to alternating parity automata (APT) by introducing a parametric version of the exponential modality of linear logic, capturing the formal properties of colors (or priorities) in higher-order model-checking. We show in particular how to reunderstand in this way the type-theoretic approach to higher-order model-checking developed by Kobayashi and Ong. We briefly explain in the end of the paper how his analysis driven by linear logic results in a new and purely semantic proof of decidability of the formulas of the monadic second-order logic for higher-order recursion schemes.Comment: 24 pages. Submitte

    Wing surface-jet interaction characteristics of an upper-surface blown model with rectangular exhaust nozzles and a radius flap

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    The wing surface jet interaction characteristics of an upper surface blown transport configuration were investigated in the Langley V/STOL tunnel. Velocity profiles at the inboard engine center line were measured for several chordwise locations, and chordwise pressure distributions on the flap were obtained. The model represented a four engine arrangement having relatively high aspect ratio rectangular spread, exhaust nozzles and a simple trailing edge radius flap

    Nanosecond molecular relaxations in lipid bilayers studied by high energy resolution neutron scattering and in-situ diffraction

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    We report a high energy-resolution neutron backscattering study to investigate slow motions on nanosecond time scales in highly oriented solid supported phospholipid bilayers of the model system DMPC -d54 (deuterated 1,2-dimyristoyl-sn-glycero-3-phoshatidylcholine), hydrated with heavy water. Wave vector resolved quasi-elastic neutron scattering (QENS) is used to determine relaxation times Ï„\tau, which can be associated with different molecular components, i.e., the lipid acyl chains and the interstitial water molecules in the different phases of the model membrane system. The inelastic data are complemented both by energy resolved and energy integrated in-situ diffraction. From a combined analysis of the inelastic data in the energy and time domain, the respective character of the relaxation, i.e., the exponent of the exponential decay is also determined. From this analysis we quantify two relaxation processes. We associate the fast relaxation with translational diffusion of lipid and water molecules while the slow process likely stems from collective dynamics

    Discovery of a supernova associated with GRB 031203: SMARTS Optical-Infrared Lightcurves from 0.2 to 92 days

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    Optical and infrared monitoring of the afterglow site of gamma-ray burst (GRB) 031203 has revealed a brightening source embedded in the host galaxy, which we attribute to the presence of a supernova (SN) related to the GRB ("SN 031203"). We present details of the discovery and evolution of SN 031203 from 0.2 to 92 days after the GRB, derived from SMARTS consortium photometry in I and J bands. A template type Ic lightcurve, constructed from SN 1998bw photometry, is consistent with the peak brightness of SN 031203 although the lightcurves are not identical. Differential astrometry reveals that the SN, and hence the GRB, occurred less than 300 h_71^-1 pc (3-sigma) from the apparent galaxy center. The peak of the supernova is brighter than the optical afterglow suggesting that this source is intermediate between a strong GRB and a supernova.Comment: 11 pages, 3 figures, submitted to ApJ Letter

    Deposition of general ellipsoidal particles

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    We present a systematic overview of granular deposits composed of ellipsoidal particles with different particle shapes and size polydispersities. We study the density and anisotropy of such deposits as functions of size polydispersity and two shape parameters that fully describe the shape of a general ellipsoid. Our results show that, while shape influences significantly the macroscopic properties of the deposits, polydispersity plays apparently a secondary role. The density attains a maximum for a particular family of non-symmetrical ellipsoids, larger than the density observed for prolate or oblate ellipsoids. As for anisotropy measures, the contact forces show are increasingly preferred along the vertical direction as the shape of the particles deviates for a sphere. The deposits are constructed by means of an efficient molecular dynamics method, where the contact forces are efficiently and accurately computed. The main results are discussed in the light of applications for porous media models and sedimentation processes.Comment: 7 pages, 8 figure

    Quasi-Particles in Two-Dimensional Hubbard Model: Splitting of Spectral Weight

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    It is shown that the energy (ε)(\varepsilon) and momentum (k)(k) dependences of the electron self-energy function Σ(k,ε+i0)≡ΣR(k,ε) \Sigma (k, \varepsilon + i0) \equiv \Sigma^{R}(k, \varepsilon) are, ImΣR(k,ε)=−aε2∣ε−ξk∣−γ(k) {\rm Im} \Sigma^{R} (k, \varepsilon) = -a\varepsilon^{2}|\varepsilon - \xi_{k}|^{- \gamma (k)} where aa is some constant, ξk=ε(k)−μ,ε(k)\xi_{k} = \varepsilon(k)-\mu, \varepsilon(k) being the band energy, and the critical exponent γ(k) \gamma(k) , which depends on the curvature of the Fermi surface at k k , satisfies, 0≤γ(k)≤1 0 \leq \gamma(k) \leq 1 . This leads to a new type of electron liquid, which is the Fermi liquid in the limit of ε,ξk→0 \varepsilon, \xi_{k} \rightarrow 0 but for ξk≠0 \xi_{k} \neq 0 has a split one-particle spectra as in the Tomonaga-Luttinger liquid.Comment: 8 pages (LaTeX) 4 figures available upon request will be sent by air mail. KomabaCM-preprint-O

    Comment on "Nucleon elastic form factors and local duality"

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    We comment on the papers "Nucleon elastic form factors and local duality" [Phys. Rev. {\bf D62}, 073008 (2000)] and "Experimental verification of quark-hadron duality" [Phys. Rev. Lett. {\bf 85}, 1186 (2000)]. Our main comment is that the reconstruction of the proton magnetic form factor, claimed to be obtained from the inelastic scaling curve thanks to parton-hadron local duality, is affected by an artifact.Comment: to appear in Phys. Rev.

    Opportunistic linked data querying through approximate membership metadata

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    Between URI dereferencing and the SPARQL protocol lies a largely unexplored axis of possible interfaces to Linked Data, each with its own combination of trade-offs. One of these interfaces is Triple Pattern Fragments, which allows clients to execute SPARQL queries against low-cost servers, at the cost of higher bandwidth. Increasing a client's efficiency means lowering the number of requests, which can among others be achieved through additional metadata in responses. We noted that typical SPARQL query evaluations against Triple Pattern Fragments require a significant portion of membership subqueries, which check the presence of a specific triple, rather than a variable pattern. This paper studies the impact of providing approximate membership functions, i.e., Bloom filters and Golomb-coded sets, as extra metadata. In addition to reducing HTTP requests, such functions allow to achieve full result recall earlier when temporarily allowing lower precision. Half of the tested queries from a WatDiv benchmark test set could be executed with up to a third fewer HTTP requests with only marginally higher server cost. Query times, however, did not improve, likely due to slower metadata generation and transfer. This indicates that approximate membership functions can partly improve the client-side query process with minimal impact on the server and its interface
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