59,409 research outputs found

    Precision thrust gage Patent

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    Development of temperature compensated thrust measuring gage for measuring forces as function of time in environment with varying temperatur

    Electromechanical flowmeter accurately monitors fluid flow

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    Electromechanical flowmeter remotely and accurately monitors the flow rate and total volume of a transparent liquid discharged from a dispensing system. A dual dispensing tube system provides a relative reference level which permits compensation for temperature variations

    Passively regulated water electrolysis rocket engine Patent

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    Water electrolysis rocket engine with self- regulating stoichiometric fuel mixing regulato

    Fluid flow meter with comparator reference means Patent

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    Photometric flow meter with comparator reference mean

    A Spinorial Hamiltonian Approach to Gravity

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    We give a spinorial set of Hamiltonian variables for General Relativity in any dimension greater than 2. This approach involves a study of the algebraic properties of spinors in higher dimension, and of the elimination of second-class constraints from the Hamiltonian theory. In four dimensions, when restricted to the positive spin-bundle, these variables reduce to the standard Ashtekar variables. In higher dimensions, the theory can either be reduced to a spinorial version of the ADM formalism, or can be left in a more general form which seems useful for the investigation of some spinorial problems such as Riemannian manifolds with reduced holonomy group. In dimensions 0(mod4)0 \pmod 4, the theory may be recast solely in terms of structures on the positive spin-bundle V+\mathbb{V}^+, but such a reduction does not seem possible in dimensions 2(mod4)2 \pmod 4, due to algebraic properties of spinors in these dimensions.Comment: 20 pages, Latex 2e. Published versio

    Jumping bristletail (Insecta: Apterygota: Microcoryphia) records in the southeastern United States

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    Few records of Microcoryphia exist for the southeastern United States, with named species being reported only from Arkansas, Tennessee, and the mid-Atlantic states, and with an unnamed species being reported from Georgia. Records are here provided from 291 specimens housed in the Mississippi Entomological Museum, including ten new species-level state records. This is also the first published report of the order Microcoryphia from Alabama and Mississippi. Species include the machilids Pedetontoides atlanticus Mendes in Alabama, Arkansas, Georgia, Mississippi, and North Carolina; Pedetontus cf. atlanticus in Kentucky; Pedetontus (Verhoeffilis) gershneri Allen in Arkansas; and Pedetontus (Pedetontus) saltator Wygodzinsky and Schmidt in Mississippi and North Carolina; and the meinertellid Machiloides banksi (Silvestri) in Alabama, Arkansas, Mississippi, and North Carolina

    Lsdiff M and the Einstein Equations

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    We give a formulation of the vacuum Einstein equations in terms of a set of volume-preserving vector fields on a four-manifold M{\cal M}. These vectors satisfy a set of equations which are a generalisation of the Yang-Mills equations for a constant connection on flat spacetime.Comment: 5 pages, no figures, Latex, uses amsfonts, amssym.def and amssym.tex. Note added on more direct connection with Yang-Mills equation

    The ADHM construction and non-local symmetries of the self-dual Yang-Mills equations

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    We consider the action on instanton moduli spaces of the non-local symmetries of the self-dual Yang-Mills equations on R4\mathbb{R}^4 discovered by Chau and coauthors. Beginning with the ADHM construction, we show that a sub-algebra of the symmetry algebra generates the tangent space to the instanton moduli space at each point. We explicitly find the subgroup of the symmetry group that preserves the one-instanton moduli space. This action simply corresponds to a scaling of the moduli space.Comment: AMSLatex, 19 pages, no figures. Some discussions clarified, and citations made more accurate. I am grateful to the referee for detailed comments. Version to appear in Communications in Mathematical Physic

    Searching with Tags: Do Tags Help Users Find Things?

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    This study examines the question of whether tags can be useful in the process of information retrieval. Participants searched a social bookmarking tool specialising in academic articles (CiteULike) and an online journal database (Pubmed). Participant actions were captured using screen capture software and they were asked to describe their search process. Users did make use of tags in their search process, as a guide to searching and as hyperlinks to potentially useful articles. However, users also made use of controlled vocabularies in the journal database to locate useful search terms and of links to related articles supplied by the database
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