12,475 research outputs found

    Interaction and Expressivity in Video Games: Harnessing the Rhetoric of Film

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    The film-maker uses the camera and editing creatively, not simply to present the action of the film but also to set up a particular relation between the action and the viewer. In 3D video games with action controlled by the player, the pseudo camera is usually less creatively controlled and has less effect on the player’s appreciation of and engagement with the game. This paper discusses methods of controlling games by easy and intuitive interfaces and use of an automated virtual camera to increase the appeal of games for users

    Cometary Astrometry

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    Modern techniques for making cometary astrometric observations, reducing these observations, using accurate reference star catalogs, and computing precise orbits and ephemerides are discussed in detail and recommendations and suggestions are given in each area

    Carbon and nitrogen dynamics: Greenhouse gases in groundwater beneath a constructed wetland treating municipal wastewater

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    Conference oral presentationConstructed wetlands (CW) act as nitrogen (N) sinks and reactors facilitating a number of physical, chemical and biological processes. The N removal efficiency of through-flowing water in such systems when used to treat municipal wastewater is variable. Their overall removal efficiencies do not specifically explain which N species have been removed by physical attenuation, and by biological assimilation or transformation to other forms. A wider understanding of how N removal occurs would help elucidate how losses of N and associated gases from CW impact on water and air quality. The objective of this study is to investigate the C and N cycling processes in the porewater of soils immediately adjacent, up-gradient and down- gradient to helophyte —vegetated CW cells

    Host Selection of the giant willow aphid (Tuberolachnus salignus)

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    The giant willow aphid [Tuberolachnus salignus (Gmelin)] has recently become noteworthy as a potential pest species due to the increased uptake of willow, its host-plant, for use in growing biomass for energy production. In this paper we describe host selection studies of T. salignus on short rotation coppice (SRC) willow varieties in laboratory bioassays and field experiments. In laboratory olfactometry tests, T. salignus was significantly attracted to certain SRC willow varieties, but not to others. Field trials during 2007 and 2008 showed that T. salignus infestation levels varied significantly on different SRC willow varieties and that levels are highest on the varieties to which they are most strongly attracted in the laboratory bioassays

    Active and passive microwave measurements in Hurricane Allen

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    The NASA Langley Research Center analysis of the airborne microwave remote sensing measurements of Hurricane Allen obtained on August 5 and 8, 1980 is summarized. The instruments were the C-band stepped frequency microwave radiometer and the Ku-band airborne microwave scatterometer. They were carried aboard a NOAA aircraft making storm penetrations at an altitude of 3000 m and are sensitive to rain rate, surface wind speed, and surface wind vector. The wind speed is calculated from the increase in antenna brightness temperature above the estimated calm sea value. The rain rate is obtained from the difference between antenna temperature increases measured at two frequencies, and wind vector is determined from the sea surface normalized radar cross section measured at several azimuths. Comparison wind data were provided from the inertial navigation systems aboard both the C-130 aircraft at 3000 m and a second NOAA aircraft (a P-3) operating between 500 and 1500 m. Comparison rain rate data were obtained with a rain radar aboard the P-3. Evaluation of the surface winds obtained with the two microwave instruments was limited to comparisons with each other and with the flight level winds. Two important conclusions are drawn from these comparisons: (1) the radiometer is accurate when predicting flight level wind speeds and rain; and (2) the scatterometer produces well behaved and consistent wind vectors for the rain free periods

    First Detection of a Strong Magnetic Field on a Bursty Brown Dwarf: Puzzle Solved

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    We report the first direct detection of a strong, 5 kG magnetic field on the surface of an active brown dwarf. LSR J1835+3259 is an M8.5 dwarf exhibiting transient radio and optical emission bursts modulated by fast rotation. We have detected the surface magnetic field as circularly polarized signatures in the 819 nm sodium lines when an active emission region faced the Earth. Modeling Stokes profiles of these lines reveals the effective temperature of 2800 K and log gravity acceleration of 4.5. These parameters place LSR J1835+3259 on evolutionary tracks as a young brown dwarf with the mass of 55±\pm4 MJ_{\rm J} and age of 22±\pm4 Myr. Its magnetic field is at least 5.1 kG and covers at least 11% of the visible hemisphere. The active region topology recovered using line profile inversions comprises hot plasma loops with a vertical stratification of optical and radio emission sources. These loops rotate with the dwarf in and out of view causing periodic emission bursts. The magnetic field is detected at the base of the loops. This is the first time that we can quantitatively associate brown dwarf non-thermal bursts with a strong, 5 kG surface magnetic field and solve the puzzle of their driving mechanism. This is also the coolest known dwarf with such a strong surface magnetic field. The young age of LSR J1835+3259 implies that it may still maintain a disk, which may facilitate bursts via magnetospheric accretion, like in higher-mass T Tau-type stars. Our results pave a path toward magnetic studies of brown dwarfs and hot Jupiters.Comment: ApJ, in pres

    The interpretation of the field angle dependence of the critical current in defect-engineered superconductors

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    We apply the vortex path model of critical currents to a comprehensive analysis of contemporary data on defect-engineered superconductors, showing that it provides a consistent and detailed interpretation of the experimental data for a diverse range of materials. We address the question of whether electron mass anisotropy plays a role of any consequence in determining the form of this data and conclude that it does not. By abandoning this false interpretation of the data, we are able to make significant progress in understanding the real origin of the observed behavior. In particular, we are able to explain a number of common features in the data including shoulders at intermediate angles, a uniform response over a wide angular range and the greater discrimination between individual defect populations at higher fields. We also correct several misconceptions including the idea that a peak in the angular dependence of the critical current is a necessary signature of strong correlated pinning, and conversely that the existence of such a peak implies the existence of correlated pinning aligned to the particular direction. The consistency of the vortex path model with the principle of maximum entropy is introduced.Comment: 14 pages, 7 figure

    Calorons in Weyl Gauge

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    We demonstrate by explicit construction that while the untwisted Harrington-Shepard caloron AμA_\mu is manifestly periodic in Euclidean time, with period β=1T\beta=\frac{1}{T}, when transformed to the Weyl (A0=0A_0=0) gauge, the caloron gauge field AiA_i is periodic only up to a large gauge transformation, with winding number equal to the caloron's topological charge. This helps clarify the tunneling interpretation of these solutions, and their relation to Chern-Simons numbers and winding numbers.Comment: 10 pages, 10 figures, a sign typo in equation 27 is correcte
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