6,113 research outputs found

    High resolution spectroscopy of two gamma-ray bursts in November 1978

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    The first results from the ISSEE-3 radiatively colled germanium gamma ray burst spectrometer are presented. Spectra and time histories from two events on the 1978 November 4 and 1978 November 19 are given. A significant difference in the continuum spectra for the two events was observed. Evidence is presented for two spectral features in the features in the November 19 events, a broad one at approximately 420 key KeV and a narrower one at 740 KeV with a suggestion of an accompanying high energy tail

    On pp-filtrations of Weyl modules

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    This paper considers Weyl modules for a simple, simply connected algebraic group over an algebraically closed field kk of positive characteristic p2p\not=2. The main result proves, if p2h2p\geq 2h-2 (where hh is the Coxeter number) and if the Lusztig character formula holds for all (irreducible modules with) regular restricted highest weights, then any Weyl module Δ(λ)\Delta(\lambda) has a Δp\Delta^p-filtration, namely, a filtration with sections of the form Δp(μ0+pμ1):=L(μ0)Δ(μ1)[1]\Delta^p(\mu_0+p\mu_1):=L(\mu_0)\otimes\Delta(\mu_1)^{[1]}, where μ0\mu_0 is restricted and μ1\mu_1 is arbitrary dominant. In case the highest weight λ\lambda of the Weyl module Δ(λ)\Delta(\lambda) is pp-regular, the pp-filtration is compatible with the G1G_1-radical series of the module. The problem of showing that Weyl modules have Δp\Delta^p-filtrations was first proposed as a worthwhile ("w\"unschenswert") problem in Jantzen's 1980 Crelle paper.Comment: Latest version corrects minor mistakes in previous versions. A reference is made to Williamson's recent arXiv posting, providing some relevant discussion in a footnote. [Comments on earlier versions: Previous v. 1 with minor errors and statements corrected. Improved organization. Should replace v. 2 which is an older version (even older than v.1) and was mistakenly posted.

    The Goddard program of gamma ray transient astronomy

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    Gamma ray burst studies are reviewed. The past results, present status and future expectations are outlined regarding endeavors using experiments on balloons, IMP-6 and -7, OGO-3, ISEE-1 and -3, Helios-2, Solar Maximum Mission, the Einstein Observatory, Solar Polar and the Gamma Ray Observatory, and with the interplanetary gamma ray burst networks, to which some of these spacecraft sensors contribute. Additional emphasis is given to the recent discovery of a new type of gamma ray transient, detected on 1979 March 5

    Status of Electroweak Phase Transition and Baryogenesis

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    I review recent progress on the electroweak phase transition and baryogenesis, focusing on the minimal supersymmetric standard model as the source of new physics.Comment: 10 pp, 6 figures; plenary talk given at 6th Workshop on High Energy Physics Phenomenology, 4 Jan. 2000, Chennai, India. v.2: added reference

    Spontaneous Symmetry Breaking in General Relativity. Vector Order Parameter

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    Gravitational properties of a hedge-hog type topological defect in two extra dimensions are considered in General Relativity employing a vector as the order parameter. All previous considerations were done using the order parameter in the form of a multiplet in a target space of scalar fields. The difference of these two approaches is analyzed and demonstrated in detail. Regular solutions of the Einstein equations are studied analytically and numerically. It is shown that the existence of a negative cosmological constant is sufficient for the spontaneous symmetry breaking of the initially plain bulk. Regular configurations have a growing gravitational potential and are able to trap the matter on the brane. If the energy of spontaneous symmetry breaking is high, the gravitational potential has several points of minimum. Identical in the uniform bulk spin-less particles, being trapped within separate minima, acquire different masses and appear to the observer on brane as different particles with integer spins.Comment: 23 pages, 6 figure

    The protein import apparatus of chloroplasts

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    Routing of cytosolically synthesized precursor proteins into chloroplasts is a specific process which involves a multitude of soluble and membrane components. In this review we wil1 focus on early events of the translocation pathway of nuclear coded plastidic precursor proteins and compare import routes for polypeptide of the outer chloroplast envelope to that of internal chloroplast compartments. A number of proteins housed in the chloroplast envelopes have been implied to be involved in the translocation process, but so far a certain function has not been assigned to any of these proteins. The only exception could be an envelope localized hsc 70 homologue which could retain the import competence of a precursor protein in transit into the organelle

    A Comparison of Self-Reported Pain Levels in Minimally-Shod vs Traditionally-Shod Runners

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    Please see the pdf version of the abstract

    Agent Based Modeling for Low-cost Counter UAS Protocol in Prisons

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    Technological advances have led to the prevalence of small unmanned aerial systems (sUAS) which has proven to be a security concern for fixed facilities to include prisons, airports, and forward operating bases. This study explores if agent-based simulation modeling can serve as a useful tool for developing counter unmanned aerial system (C-UAS) parameters for a fixed facility. The relationship between threat speed and a hypothetical C-UAS is explored in an AnyLogic model designed to represent a prison and general sUAS smuggling threats that prisons have experienced in recent years. The data suggests there is a critical threat sUAS speed in which C-UAS failures occur at a much higher frequency and that the relationship is non-linear

    Revegetation of a Waste Disposal Site in the 200 Areas of the Hanford Reservation

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    The study area is located on a portion of a former 17-acre cooling water pond. It was used from October 1951 to April 1954 to receive process vessel cooling water and steam condensate arising from operation of the Redox plant. The pond was taken out of service when an inadvertent release of fission products caused the radionuclide concentrations in the pond sediments to exceed prescribed disposal limits. At that time the pipeline to the pond was plugged and the pond allowed to dry out. The pond was covered with non-contaminated soil fill to prevent the spread of contamination by wind. Russian thistles and bursage became self-established in the area and their roots penetrated to the contaminated area. The fall of 1974 additional soil fill was added and 0.9 ha of this clean soil fill was used to establish a revegetation test area. The soil fill was wetted and compacted to reduce erosion and settling and to provide a moist environment to encourage seed germination. Four soil treatments were chosen for the experiment: a control, and soil amendments of bentonite clay, straw, and a straw/clay mixture. The degree of success of revegetation of various species under the different conditions is discussed

    Testing for Features in the Primordial Power Spectrum

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    Well-known causality arguments show that events occurring during or at the end of inflation, associated with reheating or preheating, could contribute a blue component to the spectrum of primordial curvature perturbations, with the dependence k^3. We explore the possibility that they could be observably large in CMB, LSS, and Lyman-alpha data. We find that a k^3 component with a cutoff at some maximum k can modestly improve the fits (Delta chi^2=2.0, 5.4) of the low multipoles (l ~ 10 - 50) or the second peak (l ~ 540) of the CMB angular spectrum when the three-year WMAP data are used. Moreover, the results from WMAP are consistent with the CBI, ACBAR, 2dFGRS, and SDSS data when they are included in the analysis. Including the SDSS galaxy clustering power spectrum, we find weak positive evidence for the k^3 component at the level of Delta chi' = 2.4, with the caveat that the nonlinear evolution of the power spectrum may not be properly treated in the presence of the k^3 distortion. To investigate the high-k regime, we use the Lyman-alpha forest data (LUQAS, Croft et al., and SDSS Lyman-alpha); here we find evidence at the level Delta chi^2' = 3.8. Considering that there are two additional free parameters in the model, the above results do not give a strong evidence for features; however, they show that surprisingly large bumps are not ruled out. We give constraints on the ratio between the k^3 component and the nearly scale-invariant component, r_3 < 1.5, over the range of wave numbers 0.0023/Mpc < k < 8.2/Mpc. We also discuss theoretical models which could lead to the k^3 effect, including ordinary hybrid inflation and double D-term inflation models. We show that the well-motivated k^3 component is also a good representative of the generic spikelike feature in the primordial perturbation power spectrum.Comment: 23 pages, 6 figures; added new section on theoretical motivation for k^3 term, and discussion of double D-term hybrid inflation models; title changed, added a new section discussing the generic spikelike features, published in IJMP
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