23,144 research outputs found
Small Area Shrinkage Estimation
The need for small area estimates is increasingly felt in both the public and
private sectors in order to formulate their strategic plans. It is now widely
recognized that direct small area survey estimates are highly unreliable owing
to large standard errors and coefficients of variation. The reason behind this
is that a survey is usually designed to achieve a specified level of accuracy
at a higher level of geography than that of small areas. Lack of additional
resources makes it almost imperative to use the same data to produce small area
estimates. For example, if a survey is designed to estimate per capita income
for a state, the same survey data need to be used to produce similar estimates
for counties, subcounties and census divisions within that state. Thus, by
necessity, small area estimation needs explicit, or at least implicit, use of
models to link these areas. Improved small area estimates are found by
"borrowing strength" from similar neighboring areas.Comment: Published in at http://dx.doi.org/10.1214/11-STS374 the Statistical
Science (http://www.imstat.org/sts/) by the Institute of Mathematical
Statistics (http://www.imstat.org
A Methodology for Information Flow Experiments
Information flow analysis has largely ignored the setting where the analyst
has neither control over nor a complete model of the analyzed system. We
formalize such limited information flow analyses and study an instance of it:
detecting the usage of data by websites. We prove that these problems are ones
of causal inference. Leveraging this connection, we push beyond traditional
information flow analysis to provide a systematic methodology based on
experimental science and statistical analysis. Our methodology allows us to
systematize prior works in the area viewing them as instances of a general
approach. Our systematic study leads to practical advice for improving work on
detecting data usage, a previously unformalized area. We illustrate these
concepts with a series of experiments collecting data on the use of information
by websites, which we statistically analyze
Conversion of neutron stars to strange stars as the central engine of gamma-ray bursts
We study the conversion of a neutron star to a strange star as a possible
energy source for gamma-ray bursts. We use different recent models for the
equation of state of neutron star matter and strange quark matter. We show that
the total amount of energy liberated in the conversion is in the range of (1-4)
10^{53} ergs (one order of magnitude larger than previous estimates) and is in
agreement with the energy required to power gamma-ray burst sources at
cosmological distances.Comment: ApJ, 530, 2000 February 20, Lxxx (in press
Quantum Markov chains, sufficiency of quantum channels, and Renyi information measures
A short quantum Markov chain is a tripartite state such that
system can be recovered perfectly by acting on system of the reduced
state . Such states have conditional mutual information
equal to zero and are the only states with this property. A quantum channel
is sufficient for two states and if there exists
a recovery channel using which one can perfectly recover from
and from . The relative
entropy difference
is equal to
zero if and only if is sufficient for and . In
this paper, we show that these properties extend to Renyi generalizations of
these information measures which were proposed in [Berta et al., J. Math. Phys.
56, 022205, (2015)] and [Seshadreesan et al., J. Phys. A 48, 395303, (2015)],
thus providing an alternate characterization of short quantum Markov chains and
sufficient quantum channels. These results give further support to these
quantities as being legitimate Renyi generalizations of the conditional mutual
information and the relative entropy difference. Along the way, we solve some
open questions of Ruskai and Zhang, regarding the trace of particular matrices
that arise in the study of monotonicity of relative entropy under quantum
operations and strong subadditivity of the von Neumann entropy.Comment: v4: 26 pages, 1 figure; reorganized and one open question solved with
Choi's inequality (at the suggestion of an anonymous referee
Quantum discord between relatively accelerated observers
We calculate the quantum discord between two free modes of a scalar field
which start in a maximally entangled state and then undergo a relative,
constant acceleration. In a regime where there is no distillable entanglement
due to the Unruh effect, we show that there is a finite amount of quantum
discord, which is a measure of purely quantum correlations in a state, over and
above quantum entanglement. Even in the limit of infinite acceleration of the
observer detecting one of the modes, we provide evidence for a non-zero amount
of purely quantum correlations, which might be exploited to gain non-trivial
quantum advantages.Comment: 4 pages, 2 figure
A Green-function approach to transport phenomena in quantum pumps
We present a general treatment to study transport phenomena in systems
described by tight-binding Hamiltonians coupled to reservoirs and with one or
more time-periodic potentials. We apply this treatment to the study of
transport phenomena in a double barrier structure with one and two harmonic
potentials. Among other properties, we discuss the origin of the sign of the
net current.Comment: To appear in PR
On the Observability of "Invisible" / "Nearly Invisible" Charginos
It is shown that if the charginos decay into very soft leptons or hadrons +
due to degeneracy/ near- degeneracy with the LSP or the sneutrino,
the observability of the recently proposed signal via the single photon (+ soft
particles) + channel crucially depends on the magnitude of the \SNU
mass due to destructive interferences in the matrix element squared. If the
\SNU's and, consequently, left-sleptons are relatively light, the size of the
signal, previously computed in the limit \MSNU \to \infty only, is
drastically reduced. We present the formula for the signal cross section in a
model independent way and discuss the observability of the signal at LEP 192
and NLC energies.Comment: 27 pages, Late
Probing thermality beyond the diagonal
We investigate the off-diagonal sector of eigenstate thermalization using
both local and non-local probes in 2-dimensional conformal field theories. A
novel analysis of the asymptotics of OPE coefficients via the modular bootstrap
is performed to extract the behaviour of the off-diagonal matrix elements. We
also probe this sector using semi-classical heavy-light Virasoro blocks. The
results demonstrate signatures of thermality and confirms the entropic
suppression of the off-diagonal elements as necessitated by the eigenstate
thermalization hypothesis.Comment: 27 pages, 2 figure
Strong converse theorems using R\'enyi entropies
We use a R\'enyi entropy method to prove strong converse theorems for certain
information-theoretic tasks which involve local operations and quantum or
classical communication between two parties. These include state
redistribution, coherent state merging, quantum state splitting, measurement
compression with quantum side information, randomness extraction against
quantum side information, and data compression with quantum side information.
The method we employ in proving these results extends ideas developed by Sharma
[arXiv:1404.5940], which he used to give a new proof of the strong converse
theorem for state merging. For state redistribution, we prove the strong
converse property for the boundary of the entire achievable rate region in the
-plane, where and denote the entanglement cost and quantum
communication cost, respectively. In the case of measurement compression with
quantum side information, we prove a strong converse theorem for the classical
communication cost, which is a new result extending the previously known weak
converse. For the remaining tasks, we provide new proofs for strong converse
theorems previously established using smooth entropies. For each task, we
obtain the strong converse theorem from explicit bounds on the figure of merit
of the task in terms of a R\'enyi generalization of the optimal rate. Hence, we
identify candidates for the strong converse exponents for each task discussed
in this paper. To prove our results, we establish various new entropic
inequalities, which might be of independent interest. These involve conditional
entropies and mutual information derived from the sandwiched R\'enyi
divergence. In particular, we obtain novel bounds relating these quantities, as
well as the R\'enyi conditional mutual information, to the fidelity of two
quantum states.Comment: 40 pages, 5 figures; v4: Accepted for publication in Journal of
Mathematical Physic
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