2,041 research outputs found

    New evidence for strong nonthermal effects in Tycho's supernova remnant

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    For the case of Tycho's supernova remnant (SNR) we present the relation between the blast wave and contact discontinuity radii calculated within the nonlinear kinetic theory of cosmic ray (CR) acceleration in SNRs. It is demonstrated that these radii are confirmed by recently published Chandra measurements which show that the observed contact discontinuity radius is so close to the shock radius that it can only be explained by efficient CR acceleration which in turn makes the medium more compressible. Together with the recently determined new value Esn=1.2×1051E_{sn}=1.2\times 10^{51} erg of the SN explosion energy this also confirms our previous conclusion that a TeV gamma-ray flux of (2−5)×10−13(2-5)\times 10^{-13} erg/(cm2^2s) is to be expected from Tycho's SNR. Chandra measurements and the HEGRA upper limit of the TeV gamma-ray flux together limit the source distance dd to 3.3≀d≀43.3\leq d\leq 4 kpc.Comment: 5 pages, 4 figures. Accepted for publication in Astrophysics and Space Science, Proc. of "The Multi-Messenger Approach to High-Energy Gamma-ray Sources (Third Workshop on the Nature of Unidentified High-Energy Sources)", Barcelona, July 4-7, 200

    Ground-water levels and pumpage in East St. Louis area, Illinois, 1890-1961

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    Bibliography: p. 25.Enumeration continues through succeeding title

    The Expectation Monad in Quantum Foundations

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    The expectation monad is introduced abstractly via two composable adjunctions, but concretely captures measures. It turns out to sit in between known monads: on the one hand the distribution and ultrafilter monad, and on the other hand the continuation monad. This expectation monad is used in two probabilistic analogues of fundamental results of Manes and Gelfand for the ultrafilter monad: algebras of the expectation monad are convex compact Hausdorff spaces, and are dually equivalent to so-called Banach effect algebras. These structures capture states and effects in quantum foundations, and also the duality between them. Moreover, the approach leads to a new re-formulation of Gleason's theorem, expressing that effects on a Hilbert space are free effect modules on projections, obtained via tensoring with the unit interval.Comment: In Proceedings QPL 2011, arXiv:1210.029

    Determination of the anomalous dimension of gluonic operators in deep inelastic scattering at O(1/N_f)

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    Using large N_f methods we compute the anomalous dimension of the predominantly gluonic flavour singlet twist-2 composite operator which arises in the operator product expansion used in deep inelastic scattering. We obtain a d-dimensional expression for it which depends on the operator moment n. Its expansion in powers of epsilon = (4-d)/2 agrees with the explicit exact three loop MSbar results available for n less than or equal to 8 and allows us to determine some new information on the explicit n-dependence of the three and higher order coefficients. In particular the n-dependence of the three loop anomalous dimension gamma_{gg}(a) is determined in the C_2(G) sector at O(1/N_f).Comment: 26 latex pages, 7 postscript figure

    An overview of jets and outflows in stellar mass black holes

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    In this book chapter, we will briefly review the current empirical understanding of the relation between accretion state and and outflows in accreting stellar mass black holes. The focus will be on the empirical connections between X-ray states and relativistic (`radio') jets, although we are now also able to draw accretion disc winds into the picture in a systematic way. We will furthermore consider the latest attempts to measure/order jet power, and to compare it to other (potentially) measurable quantities, most importantly black hole spin.Comment: Accepted for publication in Space Science Reviews. Also to appear in the Space Sciences Series of ISSI - The Physics of Accretion on to Black Holes (Springer Publisher

    On the derivative of the associated Legendre function of the first kind of integer order with respect to its degree

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    In our recent works [R. Szmytkowski, J. Phys. A 39 (2006) 15147; corrigendum: 40 (2007) 7819; addendum: 40 (2007) 14887], we have investigated the derivative of the Legendre function of the first kind, PÎœ(z)P_{\nu}(z), with respect to its degree Îœ\nu. In the present work, we extend these studies and construct several representations of the derivative of the associated Legendre function of the first kind, PΜ±m(z)P_{\nu}^{\pm m}(z), with respect to the degree Îœ\nu, for m∈Nm\in\mathbb{N}. At first, we establish several contour-integral representations of ∂PΜ±m(z)/∂Μ\partial P_{\nu}^{\pm m}(z)/\partial\nu. They are then used to derive Rodrigues-type formulas for [∂PΜ±m(z)/∂Μ]Îœ=n[\partial P_{\nu}^{\pm m}(z)/\partial\nu]_{\nu=n} with n∈Nn\in\mathbb{N}. Next, some closed-form expressions for [∂PΜ±m(z)/∂Μ]Îœ=n[\partial P_{\nu}^{\pm m}(z)/\partial\nu]_{\nu=n} are obtained. These results are applied to find several representations, both explicit and of the Rodrigues type, for the associated Legendre function of the second kind of integer degree and order, Qn±m(z)Q_{n}^{\pm m}(z); the explicit representations are suitable for use for numerical purposes in various regions of the complex zz-plane. Finally, the derivatives [∂2PÎœm(z)/∂Μ2]Îœ=n[\partial^{2}P_{\nu}^{m}(z)/\partial\nu^{2}]_{\nu=n}, [∂QÎœm(z)/∂Μ]Îœ=n[\partial Q_{\nu}^{m}(z)/\partial\nu]_{\nu=n} and [∂QÎœm(z)/∂Μ]Îœ=−n−1[\partial Q_{\nu}^{m}(z)/\partial\nu]_{\nu=-n-1}, all with m>nm>n, are evaluated in terms of [∂PΜ−m(±z)/∂Μ]Îœ=n[\partial P_{\nu}^{-m}(\pm z)/\partial\nu]_{\nu=n}.Comment: LateX, 40 pages, 1 figure, extensive referencin

    Electrostatic Potentials in Supernova Remnant Shocks

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    Recent advances in the understanding of the properties of supernova remnant shocks have been precipitated by the Chandra and XMM X-ray Observatories, and the HESS Atmospheric Cerenkov Telescope in the TeV band. A critical problem for this field is the understanding of the relative degree of dissipative heating/energization of electrons and ions in the shock layer. This impacts the interpretation of X-ray observations, and moreover influences the efficiency of injection into the acceleration process, which in turn feeds back into the thermal shock layer energetics and dynamics. This paper outlines the first stages of our exploration of the role of charge separation potentials in non-relativistic electron-ion shocks where the inertial gyro-scales are widely disparate, using results from a Monte Carlo simulation. Charge density spatial profiles were obtained in the linear regime, sampling the inertial scales for both ions and electrons, for different magnetic field obliquities. These were readily integrated to acquire electric field profiles in the absence of self-consistent, spatial readjustments between the electrons and the ions. It was found that while diffusion plays little role in modulating the linear field structure in highly oblique and perpendicular shocks, in quasi-parallel shocks, where charge separations induced by gyrations are small, and shock-layer electric fields are predominantly generated on diffusive scales.Comment: 7 pages, 2 embedded figures, Accepted for publication in Astrophysics and Space Science, as part of the HEDLA 2006 conference proceeding

    Solidification of Al alloys under electromagnetic pulses and characterization of the 3D microstructures under synchrotron x-ray tomography

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    A novel programmable electromagnetic pulse device was developed and used to study the solidification of Al-15 pct Cu and Al-35 pct Cu alloys. The pulsed magnetic fluxes and Lorentz forces generated inside the solidifying melts were simulated using finite element methods, and their effects on the solidification microstructures were characterized using electron microscopy and synchrotron X-ray tomography. Using a discharging voltage of 120 V, a pulsed magnetic field with the peak Lorentz force of ~1.6 N was generated inside the solidifying Al-Cu melts which were showed sufficiently enough to disrupt the growth of the primary Al dendrites and the Al2Cu intermetallic phases. The microstructures exhibit a strong correlation to the characteristics of the applied pulse, forming a periodical pattern that resonates the frequency of the applied electromagnetic field

    Metagenomic study of the viruses of African straw-coloured fruit bats: detection of a chiropteran poxvirus and isolation of a novel adenovirus

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    Viral emergence as a result of zoonotic transmission constitutes a continuous public health threat. Emerging viruses such as SARS coronavirus, hantaviruses and henipaviruses have wildlife reservoirs. Characterising the viruses of candidate reservoir species in geographical hot spots for viral emergence is a sensible approach to develop tools to predict, prevent, or contain emergence events. Here, we explore the viruses of Eidolon helvum, an Old World fruit bat species widely distributed in Africa that lives in close proximity to humans. We identified a great abundance and diversity of novel herpes and papillomaviruses, described the isolation of a novel adenovirus, and detected, for the first time, sequences of a chiropteran poxvirus closely related with Molluscum contagiosum. In sum, E. helvum display a wide variety of mammalian viruses, some of them genetically similar to known human pathogens, highlighting the possibility of zoonotic transmission

    Probing Sub-Micron Forces by Interferometry of Bose-Einstein Condensed Atoms

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    We propose a technique, using interferometry of Bose-Einstein condensed alkali atoms, for the detection of sub-micron-range forces. It may extend present searches at 1 micron by 6 to 9 orders of magnitude, deep into the theoretically interesting regime of 1000 times gravity. We give several examples of both four-dimensional particles (moduli), as well as higher-dimensional particles -- vectors and scalars in a large bulk-- that could mediate forces accessible by this technique.Comment: 32 pages, 5 figures, RevTeX4, expanded discussion of interactions, references added, to appear in PR
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