29,269 research outputs found

    Warping the Universal Extra Dimensions

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    We develop the necessary ingredients for the construction of realistic models with warped universal extra dimensions. Our investigations are based on the seven dimensional (7D) spacetime AdS_5 x T^2 and we derive the Kaluza-Klein (KK) spectra for gravitons, bulk vectors and the TeV brane localized Higgs boson. We show that, starting with a massive 7D fermion, one may obtain a single chiral massless mode whose profile is readily localized towards the Planck or TeV brane. This allows one to place the standard model fermions in the bulk and construct models of flavor as in Randall-Sundrum models. Our solution also admits the familiar KK parity of UED models so that the lightest odd KK state is stable and may be a dark matter (DM) candidate. As an additional feature the AdS_5 warping ensures that the excited modes on the torus, including the DM candidate, appear at TeV energies (as is usually assumed in UED models) even though the Planck scale sets the dimensions for the torus.Comment: 22 pages. V2 References added and minor changes mad

    Evaluation of Continuous Monitoring as a Tool for Municipal Stormwater Management Programs

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    The purpose of this study is to evaluate the uncertainty attributable to inadequate temporal sampling of stormwater discharge and water quality, and understand its implications for meeting monitoring objectives relevant to municipal separate storm sewer systems (MS4s). A methodology is presented to evaluate uncertainty attributable to inadequate temporal sampling of continuous stormflow and water quality, and a case study demonstrates the application of the methodology to six small urban watersheds (0.8-6.8 km2) and six large rural watersheds (30-16,192 km2) in Virginia. Results indicate the necessity of high-frequency continuous monitoring for accurately capturing multiple monitoring objectives, including illicit discharges, acute toxicity events, and stormflow pollutant concentrations and loads, as compared to traditional methods of sampling. For example, 1-h sampling in small urban watersheds and daily sampling in large rural watersheds would introduce uncertainty in capturing pollutant loads of 3–46% and 10–28%, respectively. Overall, the outcomes from this study highlight how MS4s can leverage continuous monitoring to meet multiple objectives under current and future regulatory environments

    Cosmic ray modulation and merged interaction regions

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    Beyond several AU, interactions among shocks and streams give rise to merged interaction regions in which the magnetic field is turbulent. The integral intensity of . 75 MeV/Nuc cosmic rays at Voyager is generally observed to decrease when a merged interaction region moves past the spacecraft and to increase during the passage of a rarefaction region. When the separation between interaction regions is relatively large, the cosmic ray intensity tends to increase on a scale of a few months. This was the case at Voyager 1 from July 1, 1983 to May 1, 1984, when the spacecraft moved from 16.7 to 19.6 AU. Changes in cosmic ray intensity were related to the magnetic field strength in a simple way. It is estimated that the diffusion coefficient in merged interaction regions at this distance is similar to 0.6 x 10 to the 22nd power sq cm/s

    Gravity on a Little Warped Space

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    We investigate the consistent inclusion of 4D Einstein gravity on a truncated slice of AdS_5 whose bulk-gravity and UV scales are much less than the 4D Planck scale, M_* << M_{Pl}. Such "Little Warped Spaces" have found phenomenological utility and can be motivated by string realizations of the Randall-Sundrum framework. Using the interval approach to brane-world gravity, we show that the inclusion of a large UV-localized Einstein-Hilbert term allows one to consistently incorporate 4D Einstein gravity into the low-energy theory. We detail the spectrum of Kaluza-Klein metric fluctuations and, in particular, examine the coupling of the little radion to matter. Furthermore, we show that Goldberger-Wise stabilization can be successfully implemented on such spaces. Our results demonstrate that realistic low-energy effective theories can be constructed on these spaces, and have relevance for existing models in the literature.Comment: 1+24 page

    Consideration of radar target glint from ST during OMV rendezvous

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    The nature of radar target glint and the factors upon which it depends when using the Hubble Space Telescope as a radar target is discussed. An analysis of the glint problem using a 35 MHz or 94 MHz radar on the orbital maneuvering vehicle is explored. A strategy for overcoming glint is suggested

    A very deep Chandra observation of Abell 1795: The Cold Front and Cooling Wake

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    We present a new analysis of very deep Chandra observations of the galaxy cluster Abell 1795. Utilizing nearly 750 ks of net ACIS imaging, we are able to resolve the thermodynamic structure of the Intracluster Medium (ICM) on length scales of ~ 1 kpc near the cool core. We find several previously unresolved structures, including a high pressure feature to the north of the BCG that appears to arise from the bulk motion of Abell 1795's cool core. To the south of the cool core, we find low temperature (~ 3 keV), diffuse ICM gas extending for distances of ~ 50 kpc spatially coincident with previously identified filaments of H-alpha emission. Gas at similar temperatures is also detected in adjacent regions without any H-alpha emission. The X-ray gas coincident with the H-alpha filament has been measured to be cooling spectroscopically at a rate of ~ 1 Solar Masses/ yr, consistent with measurements of the star formation rate in this region as inferred from UV observations, suggesting that the star formation in this filament as inferred by its Hα\alpha and UV emission can trace its origin to the rapid cooling of dense, X-ray emitting gas. The H-alpha filament is not a unique site of cooler ICM, however, as ICM at similar temperatures and even higher metallicities not cospatial with Hα\alpha emission is observed just to the west of the H-alpha filament, suggesting that it may have been uplifted by Abell 1795's central active galaxy. Further simulations of cool core sloshing and AGN feedback operating in concert with one another will be necessary to understand how such a dynamic cool core region may have originated and why the H-alpha emission is so localized with respect to the cool X-ray gas despite the evidence for a catastrophic cooling flow.Comment: 14 Pages, 10 Figures, Resubmitted to ApJ after first referee report, Higher Resolution Figures available upon reques

    Cosmic ray modulation and turbulent interaction regions near 11 AU

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    When Voyager 2 was near 11 AU, the counting rate of nuclei approx 75 MeV/nucleon decreased during the interval from July, 1982 to November, 1982, and it increased thereafter until August, 1983. A decrease in cosmic ray flux was generally associated with the passage of an interaction region in which the magnetic field strength B was higher than that predicted by the spiral field model, B sub p. Several large enhancements in B/B sup p were associated with merged interaction regions which probably resulted from the interaction of two or more distinct flows. During the passage of interaction regions the cosmic ray intensity decreased at a rate proportional to (B/B sup p -1), and during the passage of rarefaction regions (where B/B sup p 1) the cosmic ray intensity increased at a constant rate. The general form of the cosmic ray intensity profile during this approx 13 month minicycle can be described by integrating these relations using the observed B(t). Latitudinal variations of the interaction regions and of the short-term cosmic ray variations were identified
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