504 research outputs found
2015 ACVIM Small Animal Consensus Statement on Seizure Management in Dogs
This report represents a scientific and working clinical consensus statement on seizure management in dogs based on current literature and clinical expertise. The goal was to establish guidelines for a predetermined, concise, and logical sequential approach to chronic seizure management starting with seizure identification and diagnosis (not included in this report), reviewing decision‐making, treatment strategies, focusing on issues related to chronic antiepileptic drug treatment response and monitoring, and guidelines to enhance patient response and quality of life. Ultimately, we hope to provide a foundation for ongoing and future clinical epilepsy research in veterinary medicine
An Infrared Divergence Problem in the cosmological measure theory and the anthropic reasoning
An anthropic principle has made it possible to answer the difficult question
of why the observable value of cosmological constant (
GeV) is so disconcertingly tiny compared to predicted value of vacuum
energy density GeV. Unfortunately, there is a
darker side to this argument, as it consequently leads to another absurd
prediction: that the probability to observe the value for randomly
selected observer exactly equals to 1. We'll call this controversy an infrared
divergence problem. It is shown that the IRD prediction can be avoided with the
help of a Linde-Vanchurin {\em singular runaway measure} coupled with the
calculation of relative Bayesian probabilities by the means of the {\em
doomsday argument}. Moreover, it is shown that while the IRD problem occurs for
the {\em prediction stage} of value of , it disappears at the {\em
explanatory stage} when has already been measured by the observer.Comment: 9 pages, RevTe
Alfv\'en Reflection and Reverberation in the Solar Atmosphere
Magneto-atmospheres with Alfv\'en speed [a] that increases monotonically with
height are often used to model the solar atmosphere, at least out to several
solar radii. A common example involves uniform vertical or inclined magnetic
field in an isothermal atmosphere, for which the Alfv\'en speed is exponential.
We address the issue of internal reflection in such atmospheres, both for
time-harmonic and for transient waves. It is found that a mathematical boundary
condition may be devised that corresponds to perfect absorption at infinity,
and, using this, that many atmospheres where a(x) is analytic and unbounded
present no internal reflection of harmonic Alfv\'en waves. However, except for
certain special cases, such solutions are accompanied by a wake, which may be
thought of as a kind of reflection. For the initial-value problem where a
harmonic source is suddenly switched on (and optionally off), there is also an
associated transient that normally decays with time as O(t-1) or O(t-1 ln t),
depending on the phase of the driver. Unlike the steady-state harmonic
solutions, the transient does reflect weakly. Alfv\'en waves in the solar
corona driven by a finite-duration train of p-modes are expected to leave such
transients.Comment: Accepted by Solar Physic
Equilibration processes in the Warm-Hot Intergalactic Medium
The Warm-Hot Intergalactic Medium (WHIM) is thought to contribute about 40-50
% to the baryonic budget at the present evolution stage of the universe. The
observed large scale structure is likely to be due to gravitational growth of
density fluctuations in the post-inflation era. The evolving cosmic web is
governed by non-linear gravitational growth of the initially weak density
fluctuations in the dark energy dominated cosmology. Non-linear structure
formation, accretion and merging processes, star forming and AGN activity
produce gas shocks in the WHIM. Shock waves are converting a fraction of the
gravitation power to thermal and non-thermal emission of baryonic/leptonic
matter. They provide the most likely way to power the luminous matter in the
WHIM. The plasma shocks in the WHIM are expected to be collisionless.
Collisionless shocks produce a highly non-equilibrium state with anisotropic
temperatures and a large differences in ion and electron temperatures. We
discuss the ion and electron heating by the collisionless shocks and then
review the plasma processes responsible for the Coulomb equilibration and
collisional ionisation equilibrium of oxygen ions in the WHIM. MHD-turbulence
produced by the strong collisionless shocks could provide a sizeable
non-thermal contribution to the observed Doppler parameter of the UV line
spectra of the WHIM.Comment: 13 pages, 4 figures, accepted for publication in Space Science
Reviews, special issue "Clusters of galaxies: beyond the thermal view",
Editor J.S. Kaastra, Chapter 8; work done by an international team at the
International Space Science Institute (ISSI), Bern, organised by J.S.
Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke
Multimessenger astronomy with the Einstein Telescope
Gravitational waves (GWs) are expected to play a crucial role in the
development of multimessenger astrophysics. The combination of GW observations
with other astrophysical triggers, such as from gamma-ray and X-ray satellites,
optical/radio telescopes, and neutrino detectors allows us to decipher science
that would otherwise be inaccessible. In this paper, we provide a broad review
from the multimessenger perspective of the science reach offered by the third
generation interferometric GW detectors and by the Einstein Telescope (ET) in
particular. We focus on cosmic transients, and base our estimates on the
results obtained by ET's predecessors GEO, LIGO, and Virgo.Comment: 26 pages. 3 figures. Special issue of GRG on the Einstein Telescope.
Minor corrections include
Magnetic Fields, Relativistic Particles, and Shock Waves in Cluster Outskirts
It is only now, with low-frequency radio telescopes, long exposures with
high-resolution X-ray satellites and gamma-ray telescopes, that we are
beginning to learn about the physics in the periphery of galaxy clusters. In
the coming years, Sunyaev-Zeldovich telescopes are going to deliver further
great insights into the plasma physics of these special regions in the
Universe. The last years have already shown tremendous progress with detections
of shocks, estimates of magnetic field strengths and constraints on the
particle acceleration efficiency. X-ray observations have revealed shock fronts
in cluster outskirts which have allowed inferences about the microphysical
structure of shocks fronts in such extreme environments. The best indications
for magnetic fields and relativistic particles in cluster outskirts come from
observations of so-called radio relics, which are megaparsec-sized regions of
radio emission from the edges of galaxy clusters. As these are difficult to
detect due to their low surface brightness, only few of these objects are
known. But they have provided unprecedented evidence for the acceleration of
relativistic particles at shock fronts and the existence of muG strength fields
as far out as the virial radius of clusters. In this review we summarise the
observational and theoretical state of our knowledge of magnetic fields,
relativistic particles and shocks in cluster outskirts.Comment: 34 pages, to be published in Space Science Review
Regional Adoption of Business-to-Business Electronic Commerce in China: Role of E-Readiness
Adoption of B2B e-commerce is a powerful driver of economic success in developed and developing countries. However, adoption rates in developing countries lag far behind. This paper draws on the Perceived eReadiness Model and research on the influence of inter-organizational relationships and economic-cultural contexts to explain the importance of three factors—inter-organizational power dependence, cooperativeness, and regional economic-cultural differences—for achieving higher levels of Internet-based Electronic Data Interchange (EDI) in the developing country of China. We employ survey data to empirically test both the individual and joint influence of these factors. The findings suggest that beyond intra-organizational and external factors, managers and policy makers wanting to promote Internet-based EDI adoption in developing countries must also account for the inter-organizational relationships of firms and the economic and cultural circumstances of the regions in which they operate
Physics of Solar Prominences: I - Spectral Diagnostics and Non-LTE Modelling
This review paper outlines background information and covers recent advances
made via the analysis of spectra and images of prominence plasma and the
increased sophistication of non-LTE (ie when there is a departure from Local
Thermodynamic Equilibrium) radiative transfer models. We first describe the
spectral inversion techniques that have been used to infer the plasma
parameters important for the general properties of the prominence plasma in
both its cool core and the hotter prominence-corona transition region. We also
review studies devoted to the observation of bulk motions of the prominence
plasma and to the determination of prominence mass. However, a simple inversion
of spectroscopic data usually fails when the lines become optically thick at
certain wavelengths. Therefore, complex non-LTE models become necessary. We
thus present the basics of non-LTE radiative transfer theory and the associated
multi-level radiative transfer problems. The main results of one- and
two-dimensional models of the prominences and their fine-structures are
presented. We then discuss the energy balance in various prominence models.
Finally, we outline the outstanding observational and theoretical questions,
and the directions for future progress in our understanding of solar
prominences.Comment: 96 pages, 37 figures, Space Science Reviews. Some figures may have a
better resolution in the published version. New version reflects minor
changes brought after proof editin
Modified granular impact force laws for the OSIRIS-REx touchdown on the surface of asteroid (101955) Bennu
The OSIRIS-REx mission collected a sample from the surface of the asteroid (101955) Bennu in October 2020. Here we study the impact of the OSIRIS-REx Touch-and-Go Sampling Acquisition Mechanism (TAGSAM) interacting with the surface of an asteroid in the framework of granular physics. Traditional approaches to estimating the penetration depth of a projectile into a granular medium include force laws and scaling relationships formulated from laboratory experiments in terrestrial-gravity conditions. However, it is unclear that these formulations extend to the OSIRIS-REx scenario of a 1300-kg spacecraft interacting with regolith in a microgravity environment. We studied the TAGSAM interaction with Bennu through numerical simulations using two collisional codes, pkdgrav and GDC-i. We validated their accuracy by reproducing the results of laboratory impact experiments in terrestrial gravity. We then performed TAGSAM penetration simulations varying the following geotechnical properties of the regolith: packing fraction (P), bulk density, inter-particle cohesion (σc), and angle of friction (ϕ). We find that the outcome of a spacecraft-regolith impact has a non-linear dependence on packing fraction. Closely packed regolith (P≳0.6) can effectively resist the penetration of TAGSAM if ϕ≳28° and/or σc≳50 Pa. For loosely packed regolith (P≲0.5), the penetration depth is governed by a drag force that scales with impact velocity to the 4/3 power, consistent with energy conservation. We discuss the importance of low-speed impact studies for predicting and interpreting spacecraft-surface interactions. We show that these low-energy events also provide a framework for interpreting the burial depths of large boulders in asteroidal regolith
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
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