7,686 research outputs found
Statistical Analysis of a Posteriori Channel and Noise Distribution Based on HARQ Feedback
In response to a comment on one of our manuscript, this work studies the
posterior channel and noise distributions conditioned on the NACKs and ACKs of
all previous transmissions in HARQ system with statistical approaches. Our main
result is that, unless the coherence interval (time or frequency) is large as
in block-fading assumption, the posterior distribution of the channel and noise
either remains almost identical to the prior distribution, or it mostly follows
the same class of distribution as the prior one. In the latter case, the
difference between the posterior and prior distribution can be modeled as some
parameter mismatch, which has little impact on certain type of applications.Comment: 15 pages, 2 figures, 4 table
Varying-coefficient functional linear regression
Functional linear regression analysis aims to model regression relations
which include a functional predictor. The analog of the regression parameter
vector or matrix in conventional multivariate or multiple-response linear
regression models is a regression parameter function in one or two arguments.
If, in addition, one has scalar predictors, as is often the case in
applications to longitudinal studies, the question arises how to incorporate
these into a functional regression model. We study a varying-coefficient
approach where the scalar covariates are modeled as additional arguments of the
regression parameter function. This extension of the functional linear
regression model is analogous to the extension of conventional linear
regression models to varying-coefficient models and shares its advantages, such
as increased flexibility; however, the details of this extension are more
challenging in the functional case. Our methodology combines smoothing methods
with regularization by truncation at a finite number of functional principal
components. A practical version is developed and is shown to perform better
than functional linear regression for longitudinal data. We investigate the
asymptotic properties of varying-coefficient functional linear regression and
establish consistency properties.Comment: Published in at http://dx.doi.org/10.3150/09-BEJ231 the Bernoulli
(http://isi.cbs.nl/bernoulli/) by the International Statistical
Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm
Imprints of neutrino-pair flavor conversions on nucleosynthesis in ejecta from neutron-star merger remnants
The remnant of neutron star mergers is dense in neutrinos. By employing
inputs from one hydrodynamical simulation of a binary neutron star merger
remnant with a black hole of in the center, dimensionless spin
parameter and an accretion torus of , the neutrino emission
properties are investigated as the merger remnant evolves. Initially, the local
number density of is larger than that of everywhere above
the remnant. Then, as the torus approaches self-regulated equilibrium, the
local abundance of neutrinos overcomes that of antineutrinos in a funnel around
the polar region. The region where the fast pairwise flavor conversions can
occur shrinks accordingly as time evolves. Still, we find that fast flavor
conversions do affect most of the neutrino-driven ejecta. Assuming that fast
flavor conversions lead to flavor equilibration, a significant enhancement of
nuclei with mass numbers is found as well as a change of the lanthanide
mass fraction by more than a factor of a thousand. Our findings hint towards a
potentially relevant role of neutrino flavor oscillations for the prediction of
the kilonova (macronova) lightcurves and motivate further work in this
direction.Comment: 16 pages, 12 figures, minor modifications to match the published
versio
On the nuclear robustness of the r process in neutron-star mergers
We have performed r-process calculations for matter ejected dynamically in
neutron star mergers based on a complete set of trajectories from a
three-dimensional relativistic smoothed particle hydrodynamic simulation. Our
calculations consider an extended nuclear network, including spontaneous,
- and neutron-induced fission and adopting fission yield distributions
from the ABLA code. We have studied the sensitivity of the r-process abundances
to nuclear masses by using different models. Most of the trajectories,
corresponding to 90% of the ejected mass, follow a relatively slow expansion
allowing for all neutrons to be captured. The resulting abundances are very
similar to each other and reproduce the general features of the observed
r-process abundance (the second and third peaks, the rare-earth peak and the
lead peak) for all mass models as they are mainly determined by the fission
yields. We find distinct differences in the abundance yields at and just above
the third peak, which can be traced back to different predictions of neutron
separation energies for r-process nuclei around neutron number . The
remaining trajectories, which contribute 10% by mass to the total integrated
abundances, follow such a fast expansion that the r process does not use all
the neutrons. This also leads to a larger variation of abundances among
trajectories as fission does not dominate the r-process dynamics. The total
integrated abundances are dominated by contributions from the slow abundances
and hence reproduce the general features of the observed r-process abundances.
We find that at timescales of weeks relevant for kilonova light curve
calculations, the abundance of actinides is larger than the one of lanthanides.
Hence actinides can be even more important than lanthanides to determine the
photon opacities under kilonova conditions. (Abridged)Comment: 17 pages, 7 figures, resubmitted to PRC addressing referee comment
A Labelled Sequent Calculus for Public Announcement Logic
Public announcement logic(PAL) is an extension of epistemic logic (EL) with
some reduction axioms. In this paper, we propose a cut-free labelled sequent
calculus for PAL, which is an extension of that for EL with sequent rules
adapted from the reduction axioms. This calculus admits cut and allows
terminating proof search
Metabolism of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) atropisomers in tissue slices from phenobarbital or dexamethasone-induced rats is sex-dependent.
1. Chiral polychlorinated biphenyls (PCBs) such as PCB 136 enantioselectively sensitize the ryanodine receptor (RyR). In light of recent evidence that PCBs cause developmental neurotoxicity via RyR-dependent mechanisms, this suggests that enantioselective PCB metabolism may influence the developmental neurotoxicity of chiral PCBs. However, enantioselective disposition of PCBs has not been fully characterized. 2. The effect of sex and cytochrome P450 (P450) enzyme induction on the enantioselective metabolism of PCB 136 was studied using liver tissue slices prepared from naïve control (CTL), phenobarbital (PB; CYP2B inducer) or dexamethasone (DEX; CYP3A inducer) pretreated adult Sprague-Dawley rats. PCB 136 metabolism was also examined in hippocampal slices derived from untreated rat pups. 3. In liver tissue slices, hydroxylated PCB (OH-PCB) profiles depended on sex and inducer pretreatment, and OH-PCB levels followed the rank orders male > female and PB > DEX > CTL. In contrast, the enantiomeric enrichment of PCB 136 and its metabolites was independent of sex and inducer pretreatment. Only small amounts of PCB 136 partitioned into hippocampal tissue slices and no OH-PCB metabolites were detected. 4. Our results suggest that enantioselective metabolism, sex and induction status of P450 enzymes in the liver may modulate the neurotoxic outcomes of developmental exposure to chiral PCBs
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