54 research outputs found

    Audio-based event detection for sports video

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    In this paper, we present an audio-based event detection approach shown to be effective when applied to the Sports broadcast data. The main benefit of this approach is the ability to recognise patterns that indicate high levels of crowd response which can be correlated to key events. By applying Hidden Markov Model-based classifiers, where the predefined content classes are parameterised using Mel-Frequency Cepstral Coefficients, we were able to eliminate the need for defining a heuristic set of rules to determine event detection, thus avoiding a two-class approach shown not to be suitable for this problem. Experimentation indicated that this is an effective method for classifying crowd response in Soccer matches, thus providing a basis for automatic indexing and summarisation

    ASCA X-ray observations of the disk wind in the dwarf nova Z Camelopardalis

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    We present ASCA observations of the dwarf nova Z Camelopardalis during outburst and during a transition from quiescence to another outburst. At the beginning of the transition the X-ray count rate was an order of magnitude higher and the spectrum much harder than during the outburst. As the transition progressed, the spectrum remained hard as the X-ray flux decreased by a factor of 3, with no spectral softening. Spectral modelling reveals an optically-thin, high-temperature component (kT≈\approx10 keV) which dominates the transition observation and is also observed during outburst. This is expected from material accreting onto the white dwarf surface. The outburst spectra require additional emission at lower temperatures, either through an additional discrete temperature component, or a combination of a cooling flow model and an ionised absorber. Fits to both observations show large amounts of absorption (NH=8−9×1021N_H=8-9\times10^{21}cm−2^{-2}), two orders of magnitude greater than the measured interstellar value, and consistent with UV measurements of the outburst. This suggests that a disk wind is present even in the earliest stages of outburst, possibly before the outburst heating wave has reached the boundary layer.Comment: 9 pages, 9 figures, MNRAS Accepte

    Concentration Dependence of Superconductivity and Order-Disorder Transition in the Hexagonal Rubidium Tungsten Bronze RbxWO3. Interfacial and bulk properties

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    We revisited the problem of the stability of the superconducting state in RbxWO3 and identified the main causes of the contradictory data previously published. We have shown that the ordering of the Rb vacancies in the nonstoichiometric compounds have a major detrimental effect on the superconducting temperature Tc.The order-disorder transition is first order only near x = 0.25, where it cannot be quenched effectively and Tc is reduced below 1K. We found that the high Tc's which were sometimes deduced from resistivity measurements, and attributed to compounds with .25 < x < .30, are to be ascribed to interfacial superconductivity which generates spectacular non-linear effects. We also clarified the effect of acid etching and set more precisely the low-rubidium-content boundary of the hexagonal phase.This work makes clear that Tc would increase continuously (from 2 K to 5.5 K) as we approach this boundary (x = 0.20), if no ordering would take place - as its is approximately the case in CsxWO3. This behaviour is reminiscent of the tetragonal tungsten bronze NaxWO3 and asks the same question : what mechanism is responsible for this large increase of Tc despite the considerable associated reduction of the electron density of state ? By reviewing the other available data on these bronzes we conclude that the theoretical models which are able to answer this question are probably those where the instability of the lattice plays a major role and, particularly, the model which call upon local structural excitations (LSE), associated with the missing alkali atoms.Comment: To be published in Physical Review

    Movement of Heterorhabditis amazonensis and Steinernema arenarium in search of corn fall armyworm larvae in artificial conditions

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    Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) is considered to be the main pest of maize crops in Brazil. Entomopathogenic nematodes (EPN) may be used to control this pest and exhibit different, unique abilities to search for their hosts. The movement of EPN in relation to S. frugiperda was evaluated. To test for horizontal movement, a styrofoam enclosure filled with sand was divided into segments, nematodes were placed at the entrance to the enclosure and a larva was placed at the end of each division. The same approach was used to evaluate vertical movement; however, PVC pipes were used in this case. In general, the mortality was inversely proportional to the initial distance between host and nematodes. In the vertical displacement test, both nematodes were able to kill the larvae up to a distance of 25 cm. Therefore, the infective juveniles of H. amazonensis and S. arenarium can search out, infect and kill larvae of S. frugiperda at distances of up to 60 cm and 25 cm of horizontal and vertical displacement, respectively

    An X-ray survey of the young open cluster NGC 2516

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    Procedures for evaluating growth-promoting qualities of cell culture reagents

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