3,079 research outputs found

    Assessment of mapping exposed ferrous and ferric iron compounds using Skylab-EREP data

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    The author has identified the following significant results. The S190B color photography is as useful as LANDSAT data for the mapping of color differences in the rocks and soils of the terrain. An S192 ratio of 0.79 - 0.89 and 0.93 - 1.05 micron bands produced an apparently successful delineation of ferrous, ferric, and other materials, in agreement with theory and ratio code studies. From an analysis of S191 data, basalt and dacite were separated on the basis of differences in spectral emissivity in the 8.3 - 12 micron region

    A new genus and species of pemphredonine wasp in Late Cretaceous Vendean amber (Hymenoptera: Crabronidae)

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    International audienceA new genus and species of pemphredonine wasp is described and figured in Late Cretaceous (Cenomanian to Santonian) amber from VendĂ©e, in northwestern France. Menopsila dupeae n. gen. and sp., is based on a partial male preserved in a small sliver of translucent amber. The genus is placed incertae sedis within the Pemphredonini, as it intermingles features, likely plesiomorphies, of various lineages within the tribe. It likely represents a stem group to one or more of the constituent subtribes, yet it is arguably most similar to the Spilomenina.Un nouveau genre et une nouvelle espĂšce de guĂȘpe pemphredonine sont dĂ©crits de l’ambre crĂ©tacĂ© supĂ©rieur (CĂ©nomanien Ă  Santonien) de VendĂ©e, nord-ouest de la France. Menopsila dupeae n. gen. et sp., est basĂ© sur un mĂąle fragmentaire prĂ©servĂ© dans un minuscule morceau d’ambre translucide. Le genre est placĂ© incertae sedis au sein des Pemphredonini, car mĂȘlant des caractĂšres probablement plĂ©siomorphes de plusieurs lignĂ©es de cette tribu. Il reprĂ©sente vraisemblablement un groupe souche de l’une ou plus des sous-tribus constitutives des Pemphredonini, mais il est sans doute plus proche des Spilomenina

    Scaling property and peculiar velocity of global monopoles

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    We investigate the scaling property of global monopoles in the expanding universe. By directly solving the equations of motion for scalar fields, we follow the time development of the number density of global monopoles in the radiation dominated (RD) universe and the matter dominated (MD) universe. It is confirmed that the global monopole network relaxes into the scaling regime and the number per hubble volume is a constant irrespective of the cosmic time. The number density n(t)n(t) of global monopoles is given by n(t)≃(0.43±0.07)/t3n(t) \simeq (0.43\pm0.07) / t^{3} during the RD era and n(t)≃(0.25±0.05)/t3n(t) \simeq (0.25\pm0.05) / t^{3} during the MD era. We also examine the peculiar velocity vv of global monopoles. For this purpose, we establish a method to measure the peculiar velocity by use of only the local quantities of the scalar fields. It is found that v∌(1.0±0.3)v \sim (1.0 \pm 0.3) during the RD era and v∌(0.8±0.3)v \sim (0.8 \pm 0.3) during the MD era. By use of it, a more accurate analytic estimate for the number density of global monopoles is obtained.Comment: 17 pages, 8 figures, to appear in Phys. Rev.

    Increasing the efficacy of automated instruction set extension

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    The use of Instruction Set Extension (ISE) in customising embedded processors for a specific application has been studied extensively in recent years. The addition of a set of complex arithmetic instructions to a baseline core has proven to be a cost-effective means of meeting design performance requirements. This thesis proposes and evaluates a reconfigurable ISE implementation called “Configurable Flow Accelerators” (CFAs), a number of refinements to an existing Automated ISE (AISE) algorithm called “ISEGEN”, and the effects of source form on AISE. The CFA is demonstrated repeatedly to be a cost-effective design for ISE implementation. A temporal partitioning algorithm called “staggering” is proposed and demonstrated on average to reduce the area of CFA implementation by 37% for only an 8% reduction in acceleration. This thesis then turns to concerns within the ISEGEN AISE algorithm. A methodology for finding a good static heuristic weighting vector for ISEGEN is proposed and demonstrated. Up to 100% of merit is shown to be lost or gained through the choice of vector. ISEGEN early-termination is introduced and shown to improve the runtime of the algorithm by up to 7.26x, and 5.82x on average. An extension to the ISEGEN heuristic to account for pipelining is proposed and evaluated, increasing acceleration by up to an additional 1.5x. An energyaware heuristic is added to ISEGEN, which reduces the energy used by a CFA implementation of a set of ISEs by an average of 1.6x, up to 3.6x. This result directly contradicts the frequently espoused notion that “bigger is better” in ISE. The last stretch of work in this thesis is concerned with source-level transformation: the effect of changing the representation of the application on the quality of the combined hardwaresoftware solution. A methodology for combined exploration of source transformation and ISE is presented, and demonstrated to improve the acceleration of the result by an average of 35% versus ISE alone. Floating point is demonstrated to perform worse than fixed point, for all design concerns and applications studied here, regardless of ISEs employed

    Cosmological Evolution of Global Monopoles

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    We investigate the cosmological evolution of global monopoles in the radiation dominated (RD) and matter dominated (MD) universes by numerically solving field equations of scalar fields. It is shown that the global monopole network relaxes into the scaling regime, unlike the gauge monopole network. The number density of global monopoles is given by n(t)≃(0.43±0.07)/t3n(t) \simeq (0.43\pm0.07) / t^{3} during the RD era and n(t)≃(0.25±0.05)/t3n(t) \simeq (0.25\pm0.05) / t^{3} during the MD era. Thus, we have confirmed that density fluctuations produced by global monopoles become scale invariant and are given by Ύρ∌7.2(5.0)σ2/t2\delta \rho \sim 7.2(5.0) \sigma^{2} / t^{2} during the RD (MD) era, where σ\sigma is the breaking scale of the symmetry.Comment: 6 pages, 2 figures, to appear in Phys. Rev. D (R

    Lagrangian evolution of global strings

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    We establish a method to trace the Lagrangian evolution of extended objects consisting of a multicomponent scalar field in terms of a numerical calculation of field equations in three dimensional Eulerian meshes. We apply our method to the cosmological evolution of global strings and evaluate the energy density, peculiar velocity, Lorentz factor, formation rate of loops, and emission rate of Nambu-Goldstone (NG) bosons. We confirm the scaling behavior with a number of long strings per horizon volume smaller than the case of local strings by a factor of ∌\sim 10. The strategy and the method established here are applicable to a variety of fields in physics.Comment: 5 pages, 2 figure

    Crowdsourcing Image Extraction and Annotation: Software Development and Case Study

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    We describe the development of web-based software that facilitates large-scale, crowdsourced image extraction and annotation within image-heavy corpora that are of interest to the digital humanities. An application of this software is then detailed and evaluated through a case study where it was deployed within Amazon Mechanical Turk to extract and annotate faces from the archives of Time magazine. Annotation labels included categories such as age, gender, and race that were subsequently used to train machine learning models. The systemization of our crowdsourced data collection and worker quality verification procedures are detailed within this case study. We outline a data verification methodology that used validation images and required only two annotations per image to produce high-fidelity data that has comparable results to methods using five annotations per image. Finally, we provide instructions for customizing our software to meet the needs for other studies, with the goal of offering this resource to researchers undertaking the analysis of objects within other image-heavy archives

    Numerical simulations of string networks in the Abelian-Higgs model

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    We present the results of a field theory simulation of networks of strings in the Abelian Higgs model. Starting from a random initial configuration we show that the resulting vortex tangle approaches a self-similar regime in which the length density of lines of zeros of ϕ\phi reduces as t−2t^{-2}. We demonstrate that the network loses energy directly into scalar and gauge radiation. These results support a recent claim that particle production, and not gravitational radiation, is the dominant energy loss mechanism for cosmic strings. This means that cosmic strings in Grand Unified Theories are severely constrained by high energy cosmic ray fluxes: either they are ruled out, or an implausibly small fraction of their energy ends up in quarks and leptons.Comment: 4pp RevTeX, 3 eps figures, clarifications and new results included, to be published in Phys. Rev. Let
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