2,041 research outputs found
New evidence for strong nonthermal effects in Tycho's supernova remnant
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 erg of the SN
explosion energy this also confirms our previous conclusion that a TeV
gamma-ray flux of erg/(cms) 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 to 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
Bibliography: p. 25.Enumeration continues through succeeding title
The Expectation Monad in Quantum Foundations
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)
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
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
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, , with respect to its
degree . In the present work, we extend these studies and construct
several representations of the derivative of the associated Legendre function
of the first kind, , with respect to the degree , for
. At first, we establish several contour-integral
representations of . They are then
used to derive Rodrigues-type formulas for with . Next, some closed-form
expressions for 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, ; the explicit
representations are suitable for use for numerical purposes in various regions
of the complex -plane. Finally, the derivatives
, and , all with , are evaluated in terms
of .Comment: LateX, 40 pages, 1 figure, extensive referencin
Electrostatic Potentials in Supernova Remnant Shocks
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
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
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
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
- âŠ