114,093 research outputs found
Quantitative magnetic resonance image analysis via the EM algorithm with stochastic variation
Quantitative Magnetic Resonance Imaging (qMRI) provides researchers insight
into pathological and physiological alterations of living tissue, with the help
of which researchers hope to predict (local) therapeutic efficacy early and
determine optimal treatment schedule. However, the analysis of qMRI has been
limited to ad-hoc heuristic methods. Our research provides a powerful
statistical framework for image analysis and sheds light on future localized
adaptive treatment regimes tailored to the individual's response. We assume in
an imperfect world we only observe a blurred and noisy version of the
underlying pathological/physiological changes via qMRI, due to measurement
errors or unpredictable influences. We use a hidden Markov random field to
model the spatial dependence in the data and develop a maximum likelihood
approach via the Expectation--Maximization algorithm with stochastic variation.
An important improvement over previous work is the assessment of variability in
parameter estimation, which is the valid basis for statistical inference. More
importantly, we focus on the expected changes rather than image segmentation.
Our research has shown that the approach is powerful in both simulation studies
and on a real dataset, while quite robust in the presence of some model
assumption violations.Comment: Published in at http://dx.doi.org/10.1214/07-AOAS157 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Dissociation Between the Growing Opioid Demands and Drug Policy Directions Among the U.S. Older Adults with Degenerative Joint Diseases
We aim to examine temporal trends of orthopedic operations and opioid-related hospital stays among seniors in the nation and states of Oregon and Washington where marijuana legalization was accepted earlier than any others. As aging society advances in the United States (U.S.), orthopedic operations and opioid-related hospital stays among seniors increase in the nation. A serial cross-sectional cohort study using the healthcare cost and utilization project fast stats from 2006 through 2015 measured annual rate per 100,000 populations of orthopedic operations by age groups (45â64 vs 65 and older) as well as annual rate per 100,000 populations of opioid-related hospital stays among 65 and older in the nation, Oregon and Washington states from 2008 through 2017. Orthopedic operations (knee arthroplasty, total or partial hip replacement, spinal fusion or laminectomy) and opioid-related hospital stays were measured. The compound annual growth rate (CAGR) was used to quantify temporal trends of orthopedic operations by age groups as well as opioid-related hospital stays and was tested by RaoâScott correction of Ï2 for categorical variables. The CAGR (4.06%) of orthopedic operations among age 65 and older increased (P...) (See full abstract in article
What makes for prize-winning television?
We investigate the determinants of success in four international television awards festivals between 1994 and 2012. We find that countries with larger markets and greater expenditure on public broadcasting tend to win more awards, but that the degree of concentration in the market for television and rates of penetration of pay-per-view television are unrelated to success. These findings are consistent with general industrial organisation literature on quality and market size, and with media policy literature on public service broadcasting acting as a force for quality. However, we also find that âhome countriesâ enjoy a strong advantage in these festivals, which is not consistent with festival success acting as a pure proxy for television quality
THE CALIBRATION OF INCOMPLETE DEMAND SYSTEMS IN QUANTITATIVE ANALYSIS
We introduce an easily implemented and flexible calibration technique for partial demand systems, combining recent developments in incomplete demand systems and a set of restrictions conditioned on the available elasticity estimates. The technique accommodates various degrees of knowledge on cross-price elasticities, satisfies curvature restrictions, and allows the recovery of an exact welfare measure for policy analysis. The technique is illustrated with a partial demand system for food consumption in Korea for different states of knowledge on cross-price effects. The consumer welfare impact of food and agricultural trade liberalization is measured.calibration, exact welfare measure, incomplete demand systems, policy analysis., Demand and Price Analysis,
Juries and Justice: Are Malpractice and Other Personal Injuries Created Equal?
A study analyzed the civil jury system and the difference in personal injury awards between automobile and deep-pocket defendants, especially in medical malpractice cases. Six conclusions were reached, including the finding that juries sometimes respond emotionally and award some objectively similar cases higher damages than others
Economic Prediction of Sport Performances: From Beijing Olympics to 2010 FIFA World Cup in South Africa
This paper uses forecasting techniques to predict outcomes in the Beijing Olympics and 2010 World Cup using economic variables.sport, Olympics, World Cup
Competitive tendering in the Scottish National Health Service Was it compulsory, and did it make a difference?(*)
This paper examines the implementation of competitive tendering in the Scottish National Health Service. Data relating to cleaning, catering and laundering services-- the three services targeted for competitive tendering--are examined. Our analysis suggests that for the first four years the request to market test was largely ignored in Scotland. In 1987 it become a management requirement, and within three years of its fresh start implementation of this policy more than matched the corresponding experience in England.
A Conditional Empirical Likelihood Based Method for Model Parameter Estimation from Complex survey Datasets
We consider an empirical likelihood framework for inference for a statistical
model based on an informative sampling design. Covariate information is
incorporated both through the weights and the estimating equations. The
estimator is based on conditional weights. We show that under usual conditions,
with population size increasing unbounded, the estimates are strongly
consistent, asymptotically unbiased and normally distributed. Our framework
provides additional justification for inverse probability weighted score
estimators in terms of conditional empirical likelihood. In doing so, it
bridges the gap between design-based and model-based modes of inference in
survey sampling settings. We illustrate these ideas with an application to an
electoral survey
Spin paramagnetism in d-wave superconductors
The Ginzburg-Landau equations are derived from the microscopic theory for
clean layered superconductors with pairing symmetry, including
the Pauli paramagnetism effect. The upper critical field parallel to
the axis is calculated. A comparison with the experimental data for YBCO
suggests that, relative to the orbital effect, the Pauli paramagnetism
contribution to is significant. The reversible magnetization in
high magnetic fields is also calculated, showing strong temperature dependence
of the slope , as a consequence of the spin paramagnetism. A simple
expression for the high temperature spin susceptibility is derived, in a good
agreement with the Knight shift measurements on YBCO.Comment: 8 pages, 3 figures; minor changes are included; reference 35 is
added; shorter version will be published in Phys. Rev. B, scheduled issue 01
July 200
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