46,049 research outputs found

    Higgs with Hadronic Signatures

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    The decay of the Higgs boson to b quarks should be the dominant decay mode, but it has not yet been conclusively established. The LHC run 1 results are recalled and the current status of the LHC Run 2 studies is reviewed. The analysis is approaching decisive sensitivity.Comment: 4 page Moriond QCD 2017 writeu

    Analysis of a Model Biological Switch

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    A model mechanism proposed by Murray [Phil. Traps. Roy. Soc. London B, 295 (1981), pp. 473–496] for generating wing patterns and eyespots on butterflies and moths is based on a morphogen (S) activated biological switch for a gene product (g). We analyse one of the resulting partial differential equation systems, namely S_t = DΔS - kS, g_t = k_tS + αg (g-k_2) (g_c-g ), where D,k,k_1 ,k_2 ,g_c > k_2 and α are positive constants. We determine analytically the size of the spatial domain where g → g_c as t → ∞ after an influx of S at the origin. This gives the size of the eyespot in terms of the mechanism parameters. The analytical problem is a nontrivial singular perturbation expansion which we discuss in detail

    Simultaneous localization and map-building using active vision

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    An active approach to sensing can provide the focused measurement capability over a wide field of view which allows correctly formulated Simultaneous Localization and Map-Building (SLAM) to be implemented with vision, permitting repeatable long-term localization using only naturally occurring, automatically-detected features. In this paper, we present the first example of a general system for autonomous localization using active vision, enabled here by a high-performance stereo head, addressing such issues as uncertainty-based measurement selection, automatic map-maintenance, and goal-directed steering. We present varied real-time experiments in a complex environment.Published versio

    Development of a prototype waste collection system /the Hydro-John/

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    Characteristics of prototype waste collection system for spacecraft application

    Correction of laser range tracking data for atmospheric refraction at elevations above 10 degrees

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    A formula for correcting laser measurements of satellite range for the effect of atmospheric refraction is given. The corrections apply above 10 deg elevation to satellites whose heights exceed 70 km. The meteorological measurements required are the temperature, pressure, and relative humidity of the air at the laser site at the time of satellite pass. The accuracy of the formula was tested by comparison with corrections obtained by ray-tracing radiosonde profiles. The standard deviation of the difference between the refractive retardation given by the formula and that calculated by ray-tracing was less than about 0.04% of the retardation or about 0.5 cm at 10 deg elevation, decreasing to 0.04 cm near zenith

    A computer vision approach to classification of birds in flight from video sequences

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    Bird populations are an important bio-indicator; so collecting reliable data is useful for ecologists helping conserve and manage fragile ecosystems. However, existing manual monitoring methods are labour-intensive, time-consuming, and error-prone. The aim of our work is to develop a reliable system, capable of automatically classifying individual bird species in flight from videos. This is challenging, but appropriate for use in the field, since there is often a requirement to identify in flight, rather than when stationary. We present our work in progress, which uses combined appearance and motion features to classify and present experimental results across seven species using Normal Bayes classifier with majority voting and achieving a classification rate of 86%

    Causality Violations in Cascade Models of Nuclear Collisions

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    Transport models have successfully described many aspects of intermediate energy heavy-ion collision dynamics. As the energies increase in these models to the ultrarelativistic regime, Lorentz covariance and causality are not strictly respected. The standard argument is that such effects are not important to final results; but they have not been seriously considered at high energies. We point out how and why these happen, how serious of a problem they may be and suggest ways of reducing or eliminating the undesirable effects.Comment: RevTeX, 23 pages, 9 (uuencoded) figures; to appear in Phys. Rev

    Matrix partitioning and EOF/principal component analysis of Antarctic Sea ice brightness temperatures

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    A field of measured anomalies of some physical variable relative to their time averages, is partitioned in either the space domain or the time domain. Eigenvectors and corresponding principal components of the smaller dimensioned covariance matrices associated with the partitioned data sets are calculated independently, then joined to approximate the eigenstructure of the larger covariance matrix associated with the unpartitioned data set. The accuracy of the approximation (fraction of the total variance in the field) and the magnitudes of the largest eigenvalues from the partitioned covariance matrices together determine the number of local EOF's and principal components to be joined by any particular level. The space-time distribution of Nimbus-5 ESMR sea ice measurement is analyzed