207 research outputs found

    Influence of radiative damping on the optical-frequency susceptibility

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    Motivated by recent discussions concerning the manner in which damping appears in the electric polarizability, we show that (a) there is a dependence of the nonresonant contribution on the damping and that (b) the damping enters according to the "opposite sign prescription." We also discuss the related question of how the damping rates in the polarizability are related to energy-level decay rates

    Hydrology and Meteorology of the Central Alaskan Arctic: Data Collection and Analysis

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    The availability of environmental data for unpopulated areas of Alaska can best be described as sparse; however, these areas have resource development potential. The central Alaskan Arctic region north of the Brooks Range (referred to as the North Slope) is no exception in terms of both environmental data and resource potential. This area was the focus of considerable oil/gas exploration immediately following World War II. Unfortunately, very little environmental data were collected in parallel with the exploration. Soon after the oil discovery at Prudhoe Bay in November 1968, the U.S. Geological Survey (USGS) started collecting discharge data at three sites in the neighborhood of Prudhoe Bay and one small watershed near Barrow. However, little complementary meteorological data (like precipitation) were collected to support the streamflow observations. In 1985, through a series of funded research projects, researchers at the University of Alaska Fairbanks (UAF), Water and Environmental Research Center (WERC), began installing meteorological stations on the North Slope in the central Alaskan Arctic. The number of stations installed ranged from 1 in 1985 to 3 in 1986, 12 in 1996, 24 in 2006, 23 in 2010, and 7 in 2014. Researchers from WERC also collected hydrological data at the following streams: Imnavait Creek (1985 to present), Upper Kuparuk River (1993 to present), Putuligayuk River (1999 to present, earlier gauged by USGS), Kadleroshilik River (2006 to 2010), Shaviovik River (2006 to 2010), No Name River (2006 to 2010), Chandler River (2009 to 2013), Anaktuvuk River (2009 to 2013), Lower Itkillik River (2012 to 2013), and Upper Itkillik River (2009 to 2013). These catchments vary in size, and runoff generation can emanate from the coastal plain, the foothills or mountains, or any combination of these locations. Snowmelt runoff in late May/early June is the most significant hydrological event of the year, except at small watersheds. For these watersheds, rain/mixed snow events in July and August have produced the floods of record. Ice jams are a major concern, especially in the larger river systems. Solid cold season precipitation is mostly uniform over the area, while warm season precipitation is greater in the mountains and foothills than on the coastal plain (roughly 3:2:1, mountains:foothills: coastal plain).The results reported here are primarily for the drainages of the Itkillik, Anaktuvuk, and Chandler River basins, where a proposed transportation corridor is being considered. Results for 2011 and before can be found in earlier reports.ABSTRACT ..................................................................................................................................... i LIST OF FIGURES ........................................................................................................................ v LIST OF TABLES .......................................................................................................................... x ACKNOWLEDGMENTS AND DISCLAIMER ........................................................................ xiii CONVERSION FACTORS, UNITS, WATER QUALITY UNITS, VERTICAL AND HORIZONTAL DATUM, ABBREVIATIONS, AND SYMBOLS ........................................... xiv ABBREVIATIONS, ACRONYMS, AND SYMBOLS .............................................................. xvi 1 INTRODUCTION ................................................................................................................... 1 2 PRIOR RELATED PUBLICATIONS .................................................................................... 5 3 STUDY AREA ........................................................................................................................ 7 4 PREVIOUS STUDIES .......................................................................................................... 11 5 METHODOLOGY AND EQUIPMENT .............................................................................. 15 5.1 Acoustic Doppler Current Profiler ................................................................................. 17 5.2 Discharge Measurements ............................................................................................... 17 5.3 Suspended Sediments ..................................................................................................... 20 5.3.1 River Sediment ........................................................................................................ 21 5.3.2 Suspended Sediment Observations ......................................................................... 21 5.3.3 Suspended Sediment Discharge .............................................................................. 22 5.3.4 Turbidity ................................................................................................................. 23 5.3.5 Bed Sediment Distribution ...................................................................................... 23 5.3.6 Suspended Sediment Grain-Size Distribution ........................................................ 24 6 RESULTS .............................................................................................................................. 25 6.1 Air Temperature and Relative Humidity ........................................................................ 25 6.2 Wind Speed and Direction ............................................................................................. 30 6.3 Net Radiation .................................................................................................................. 38 6.4 Warm Season Precipitation ............................................................................................ 40 6.5 Cold Season Precipitation .............................................................................................. 46 6.6 Annual Precipitation ....................................................................................................... 52 6.7 Soil ................................................................................................................................. 55 6.7.1 Soil Temperature ..................................................................................................... 56 6.7.1.1 Results ................................................................................................................. 57 6.7.2 Soil Moisture ........................................................................................................... 60 6.7.2.1 Results ................................................................................................................. 61 6.8 North Slope Climatology ............................................................................................... 63 6.8.1 Air Temperature ...................................................................................................... 63 6.8.2 Precipitation ............................................................................................................ 65 6.8.2.1 Warm Season Precipitation ................................................................................. 65 6.8.2.2 Cold Season Precipitation ................................................................................... 68 6.8.2.3 Annual Total Precipitation .................................................................................. 70 6.9 Surface Water Hydrology ............................................................................................... 72 6.9.1 Itkillik River ............................................................................................................ 73 6.9.2 Upper Itkillik River ................................................................................................. 74 6.9.2.1 Dye Trace Results, Upper Itkillik River .............................................................. 81 6.9.3 Lower Itkillik River 2013 Breakup and Spring Flood ............................................ 84 6.9.4 Anaktuvuk River ..................................................................................................... 91 6.9.5 Chandler River ...................................................................................................... 100 6.9.6 Additional Field Observations .............................................................................. 107 6.10 River Sediment Results ................................................................................................ 117 6.10.1 Correlation between Isco and Depth-Integrated Samples ..................................... 117 6.10.2 Suspended Sediment Rating Curves ..................................................................... 118 6.10.3 Suspended Sediment Concentrations .................................................................... 119 6.10.4 Suspended Sediment Discharge ............................................................................ 125 6.10.5 Turbidity ............................................................................................................... 129 6.10.6 Bed Sediment Distribution .................................................................................... 134 6.10.7 Suspended Sediment Grain-Size Distribution ...................................................... 136 7 HYDROLOGIC ANALYSIS .............................................................................................. 139 7.1 Precipitation Frequency Analysis ................................................................................. 139 7.2 Manning’s Roughness Coefficient (n) Calculations Revisited .................................... 142 7.3 Hydrological Modeling ................................................................................................ 147 8 CONCLUSIONS ................................................................................................................. 157 9 REFERENCES .................................................................................................................... 163 10 APPENDICES ..................................................................................................................... 169 Appendix A – Air Temperature and Relative Humidity Appendix B – Wind Speed and Direction: Wind Roses Appendix C – Cumulative Warm Season Precipitation for All Years at Each Station and Cumulative Warm Season Precipitation by Year for All Stations, 2007 to 2013 Appendix D – Soil Temperature and Moisture Content Appendix E – Rating Curves and Discharge Measurement Summarie

    The Muonium Atom as a Probe of Physics beyond the Standard Model

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    The observed interactions between particles are not fully explained in the successful theoretical description of the standard model to date. Due to the close confinement of the bound state muonium (M=μ+eM = \mu^+ e^-) can be used as an ideal probe of quantum electrodynamics and weak interaction and also for a search for additional interactions between leptons. Of special interest is the lepton number violating process of sponteanous conversion of muonium to antimuonium.Comment: 15 pages,6 figure

    Ohm's Law for Plasma in General Relativity and Cowling's Theorem

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    The general-relativistic Ohm's law for a two-component plasma which includes the gravitomagnetic force terms even in the case of quasi-neutrality has been derived. The equations that describe the electromagnetic processes in a plasma surrounding a neutron star are obtained by using the general relativistic form of Maxwell equations in a geometry of slow rotating gravitational object. In addition to the general-relativistic effect first discussed by Khanna \& Camenzind (1996) we predict a mechanism of the generation of azimuthal current under the general relativistic effect of dragging of inertial frames on radial current in a plasma around neutron star. The azimuthal current being proportional to the angular velocity ω\omega of the dragging of inertial frames can give valuable contribution on the evolution of the stellar magnetic field if ω\omega exceeds 2.7×1017(n/σ)s12.7\times 10^{17} (n/\sigma) \textrm{s}^{-1} (nn is the number density of the charged particles, σ\sigma is the conductivity of plasma). Thus in general relativity a rotating neutron star, embedded in plasma, can in principle generate axial-symmetric magnetic fields even in axisymmetry. However, classical Cowling's antidynamo theorem, according to which a stationary axial-symmetric magnetic field can not be sustained against ohmic diffusion, has to be hold in the general-relativistic case for the typical plasma being responsible for the rotating neutron star.Comment: Accepted for publication in Astrophysics & Space Scienc

    Scattering of elastic waves by periodic arrays of spherical bodies

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    We develop a formalism for the calculation of the frequency band structure of a phononic crystal consisting of non-overlapping elastic spheres, characterized by Lam\'e coefficients which may be complex and frequency dependent, arranged periodically in a host medium with different mass density and Lam\'e coefficients. We view the crystal as a sequence of planes of spheres, parallel to and having the two dimensional periodicity of a given crystallographic plane, and obtain the complex band structure of the infinite crystal associated with this plane. The method allows one to calculate, also, the transmission, reflection, and absorption coefficients for an elastic wave (longitudinal or transverse) incident, at any angle, on a slab of the crystal of finite thickness. We demonstrate the efficiency of the method by applying it to a specific example.Comment: 19 pages, 5 figures, Phys. Rev. B (in press

    Visual Ability and Searching Behavior of Adult Laricobius nigrinus, a Hemlock Woolly Adelgid Predator

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    Very little is known about the searching behavior and sensory cues that Laricobius spp. (Coleoptera: Derodontidae) predators use to locate suitable habitats and prey, which limits our ability to collect and monitor them for classical biological control of adelgids (Hemiptera: Adelgidae). The aim of this study was to examine the visual ability and the searching behavior of newly emerged L. nigrinus Fender, a host-specific predator of the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Phylloxeroidea: Adelgidae). In a laboratory bioassay, individual adults attempting to locate an uninfested eastern hemlock seedling under either light or dark conditions were observed in an arena. In another bioassay, individual adults searching for prey on hemlock seedlings (infested or uninfested) were continuously video-recorded. Beetles located and began climbing the seedling stem in light significantly more than in dark, indicating that vision is an important sensory modality. Our primary finding was that searching behavior of L. nigrinus, as in most species, was related to food abundance. Beetles did not fly in the presence of high A. tsugae densities and flew when A. tsugae was absent, which agrees with observed aggregations of beetles on heavily infested trees in the field. At close range of prey, slow crawling and frequent turning suggest the use of non-visual cues such as olfaction and contact chemoreception. Based on the beetles' visual ability to locate tree stems and their climbing behavior, a bole trap may be an effective collection and monitoring tool

    The Immune Landscape of Cancer

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    We performed an extensive immunogenomic analysis of more than 10,000 tumors comprising 33 diverse cancer types by utilizing data compiled by TCGA. Across cancer types, we identified six immune subtypes—wound healing, IFN-γ dominant, inflammatory, lymphocyte depleted, immunologically quiet, and TGF-β dominant—characterized by differences in macrophage or lymphocyte signatures, Th1:Th2 cell ratio, extent of intratumoral heterogeneity, aneuploidy, extent of neoantigen load, overall cell proliferation, expression of immunomodulatory genes, and prognosis. Specific driver mutations correlated with lower (CTNNB1, NRAS, or IDH1) or higher (BRAF, TP53, or CASP8) leukocyte levels across all cancers. Multiple control modalities of the intracellular and extracellular networks (transcription, microRNAs, copy number, and epigenetic processes) were involved in tumor-immune cell interactions, both across and within immune subtypes. Our immunogenomics pipeline to characterize these heterogeneous tumors and the resulting data are intended to serve as a resource for future targeted studies to further advance the field. Thorsson et al. present immunogenomics analyses of more than 10,000 tumors, identifying six immune subtypes that encompass multiple cancer types and are hypothesized to define immune response patterns impacting prognosis. This work provides a resource for understanding tumor-immune interactions, with implications for identifying ways to advance research on immunotherapy

    New Strong-Field QED Effects at ELI: Nonperturbative Vacuum Pair Production

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    Since the work of Sauter, and Heisenberg, Euler and K\"ockel, it has been understood that vacuum polarization effects in quantum electrodynamics (QED) predict remarkable new phenomena such as light-light scattering and pair production from vacuum. However, these fundamental effects are difficult to probe experimentally because they are very weak, and they are difficult to analyze theoretically because they are highly nonlinear and/or nonperturbative. The Extreme Light Infrastructure (ELI) project offers the possibility of a new window into this largely unexplored world. I review these ideas, along with some new results, explaining why quantum field theorists are so interested in this rapidly developing field of laser science. I concentrate on the theoretical tools that have been developed to analyze nonperturbative vacuum pair production.Comment: 20 pages, 9 figures; Key Lecture at the ELI Workshop and School on "Fundamental Physics with Ultra-High Fields", 29 Sept - 2 Oct. 2008, Frauenworth Monastery, Germany; v2: refs updated, English translations of reviews of Nikishov and Ritu
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