3,514 research outputs found
On dynamical probabilities, or: how to learn to shoot straight
© IFIP International Federation for Information Processing 2016.In order to support, for example, a quantitative analysis of various algorithms, protocols etc. probabilistic features have been introduced into a number of programming languages and calculi. It is by now quite standard to define the formal semantics of (various) probabilistic languages, for example, in terms of Discrete Time Markov Chains (DTMCs). In most cases however the probabilities involved are represented by constants, i.e. one deals with static probabilities. In this paper we investigate a semantical framework which allows for changing, i.e. dynamic probabilities which is still based on time-homogenous DTMCs, i.e. the transition matrix representing the semantics of a program does not change over time
Next-to-Leading Order QCD Corrections to Spectator Effects in Lifetimes of Beauty Hadrons
Theoretical predictions of beauty hadron lifetimes, based on the heavy quark
expansion up to and including order 1/mb^2, do not to reproduce the
experimental measurements of the lifetime ratios tau(B+)/tau(Bd) and
tau(Lambdab)/tau(Bd). Large corrections to these predictions come from
phase-space enhanced 1/mb^3 contributions, i.e. hard spectator effects. In this
paper we calculate the next-to-leading order QCD corrections to the Wilson
coefficients of the local operators appearing at O(1/mb^3). We find that these
corrections improve the agreement with the experimental data. The lifetime
ratio of charged to neutral B mesons, tau(B+)/tau(Bd), turns out to be in very
good agreement with the corresponding measurement, whereas for tau(Bs)/tau(Bd)
and tau(Lambdab)/tau(Bd) there is a residual difference at the 1-sigma level.
We discuss, however, why the theoretical predictions are less accurate in the
latter cases.Comment: 29 pages, 7 figures, uses epsf. Misprints in eqs. (28) and (52)
corrected. Results unchanged. Final version to appear on Nucl.Phys.
Light hadrons with improved staggered quarks: approaching the continuum limit
We have extended our program of QCD simulations with an improved
Kogut-Susskind quark action to a smaller lattice spacing, approximately 0.09
fm. Also, the simulations with a approximately 0.12 fm have been extended to
smaller quark masses. In this paper we describe the new simulations and
computations of the static quark potential and light hadron spectrum. These
results give information about the remaining dependences on the lattice
spacing. We examine the dependence of computed quantities on the spatial size
of the lattice, on the numerical precision in the computations, and on the step
size used in the numerical integrations. We examine the effects of
autocorrelations in "simulation time" on the potential and spectrum. We see
effects of decays, or coupling to two-meson states, in the 0++, 1+, and 0-
meson propagators, and we make a preliminary mass computation for a radially
excited 0- meson.Comment: 43 pages, 16 figure
Mode Confinement in Photonic Quasi-Crystal Point-Defect Cavities for Particle Accelerators
In this Letter, we present a study of the confinement properties of
point-defect resonators in finite-size photonic-bandgap structures composed of
aperiodic arrangements of dielectric rods, with special emphasis on their use
for the design of cavities for particle accelerators. Specifically, for
representative geometries, we study the properties of the fundamental mode (as
a function of the filling fraction, structure size, and losses) via 2-D and 3-D
full-wave numerical simulations, as well as microwave measurements at room
temperature. Results indicate that, for reduced-size structures, aperiodic
geometries exhibit superior confinement properties by comparison with periodic
ones.Comment: 4 pages, 4 figures, accepted for publication in Applied Physics
Letter
Estimating offspring production using capture-mark-recapture and genetic methods in red squirrels.
Reproductive rate is a key demographic
parameter of life history and population ecology.
In traditional population-ecology studies of small
mammals, this and other vital rates are inferred from
capture-mark-recapture (CMR) data. However, CMR
assumes that immigrants at first capture can be distinguished
from unmarked locally born offspring, an
assumption not always met. We verified CMR estimates
of locally born red squirrel (Sciurus vulgaris) offspring as
a measure of reproductive rate, with candidate offspring
(CO)\u2013candidate parent (mothers, CPs) assignment by
CERVUS, using ten DNA microsatellite loci. Seventytwo
of 122 candidate offspring (59%) were assigned to
52 of 125 CPs in six populations. Estimates of mean
litter size were 1.5 young (range 1\u20133). The 50 CO (41%)
not assigned to a reproducing female in the study site
were considered immigrants. Parentage assignment also
provided evidence of dispersal between two of our sites.
Overall, CMR and CERVUS agreed in 77% of cases.
Considering only the 55 juveniles determined as locally
born by CMR, 50 (91%) were also assigned as local
offspring with CERVUS. The main discrepancy between
the two methods was that 22 subadult squirrels classified
immigrants by CMR, were assigned by CERVUS to
females which had reproduced in our sites. It is concluded
that although in our study system agreement
between CMR and CERVUS in determining local offspring
was high, using genetic parentage assignment
helped to correctly classify some subadults, considered
immigrants by CMR, as locally born. Hence, in largescale
demographic studies, combining CMR with parentage
assignment will allow more precise estimates of
reproduction and dispersal
Prospects for detecting Gamma-Ray Bursts with the Cherenkov Telescope Array
The Large Area Telescope (LAT) on the Fermi gamma-ray satellite telescope observes Gamma-Ray Bursts (GRBs) at energies above 100 MeV. Thanks to a new detection algorithm and a new event reconstruction, it is expected to publish a catalogue with more than 100 GRBs. This work aims at revising the prospects for GRB alerts with the Cherenkov Telescope Array (CTA) based on the new LAT results. We start by considering the simulation of the observations with the full CTA of two extremely bright events, the long GRB 130427A and the short GRB 090510; then we investigate how these GRBs would be observed by different subsamples of the array pointing to different directions, adopting the \u201ccoupled divergent\u201d mode
Deixis discursiva y cohésion textual: recursos para la redacción de textos
Existe una forma de la deixis discursiva que ha recibido poca atención, y sin embargo puede resultar de gran apoyo en la lingüística aplicada, en particular para la enseñanza de la redacción. Se trata de la dinámica del despliegue textual a partir de unidades de cohesión textual basados en los demostrativos neutros. Para el caso del español, es la situación particular de su uso comosintetizadores de información (deícticos discursivos) que facilitan la continuidad temática y el despliegue textual del universo del discurso. Con fundamento en la pragmática contrastiva y los estudios de cohesión textual, el artículo aborda el uso de los deícticos discursivos como prototípicos de la comunicación oral y de la redacción de inexpertos en el manejo de la escritura, y que pueden servir de apoyo para el monitoreo y la revisión de la redacción, tanto paraescritores de español en lengua materna como para la enseñanza de español como L2. En el artículo se comparan textos orales obtenidos de situaciones comunicativas cotidianas con escritos de estudiantes universitarios, lo que permite describir y analizar las características de la deixis discursiva, para finalmente proponer algunas rutas para mejorar la enseñanza de la escritura enel nivel de la cohesión del texto escrito
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