Significance of Increased CIMT with Coexisting Carotid Plaques in Cerebral White Matter Lesions in Elders

It is very common that increased carotid intima media thickness （CIMT） and carotid plaque coexist in a single subject in elderly patients with white matter lesions （WMLs）. In this study we inves- tigated whether the coexistence of increased CIMT and carotid plaque is more strongly associated with the presence and extent of WMLs than either alone. All patients were classified into 1 of the following 4 groups： without either increased CIMT （I） or carotid plaque （P）： I（-）P（-）; with only increased CIMT： I（＋）P（-）; with only carotid plaque： I（-）P（＋）; and with both increased CIMT and carotid plaque： I（＋）P（＋） The presence and severity of periventricular WMLs （PWMLs） and deep WMLs （DWMLs） were as- sessed and the prevalence of MRI findings by the Cochran-Armitage trend test was calculated. The characteristics of subjects showed that the percentages of patients with increased CIMT and carotid plaque in the DWMLs group and the PWMLs group were significantly higher than those without WMLs group. Both DWMLs and PWMLs were strongly associated with age, carotid plaque and CIMT. Furthermore, the Cochran-Armitage trend test indicated that the prevalence of MRI findings of PWMLs and DWMLs increased in the order of I（-）P（-）〈 I（＋）P（-）〈 I（-）P（＋）〈 I（＋）P（＋） （P〈0.0001）. For the pa- tients with DWMLs, the grades of both I（＋）P（-） and I（＋）P（＋） were increased significantly compared to I（-）P（-） （P〈0.0025, P〈0.05, respectively） without such a difference found in patients with PWMLs. Our results suggested that the coexistence of increased CIMT and carotid plaque is most closely associated with WMLs, and that increased CIMT is associated with the severity of DWMLs, whereas carotid plaque is related to the presence of WMLs.

Bayesian Estimation and Prediction for the Maxwell Failure Distribution Based on Type II Censored Data

We present Bayes estimators, highest posterior density (HPD) intervals, and maximum likelihood estimators (MLEs), for the Maxwell failure distribution based on Type II censored data, i.e. using the first r lifetimes from a group of n components under test. Reliability/Hazard function estimates, Bayes predictive distributions and highest posterior density prediction intervals for a future observation are also considered. Two data examples and a Monte Carlo simulation study are used to illustrate the results and to compare the performances of the different methods.

Foodweb Trophic Level and Diet Inference Using an Extended Bayesian Stable Isotope Mixing Model

You are what you eat (diet) and where you eat (trophic level) in the food web. The relative abundance of pairs of stable isotopes of the organic elements carbon (e.g., the isotope ratio of 13C vs 12C), nitrogen, and sulfur, among others, in the tissues of a consumer reflects a weighted-average of the isotope ratios in the sources it consumes, after some corrections for the processes of digestion and assimilation. We extended a Bayesian mixing model to infer trophic positions of consumer organisms in a food web in addition to the degree to which distinct resource pools (diet sources) support consumers. The novel features in this work include: 1) trophic level estimation (vertical position in foodweb) and 2) the Bayesian exposition of a biologically realistic model [1] including stable isotope ratios and concentrations of carbon, nitrogen, and sulfur, isotopic fractionations, elemental assimilation efficiencies, as well as extensive use of prior information. We discuss issues of parameter identifiability in the complex and most realistic model. We apply our model to simulated data and to bottlenose dolphins (Tursiops truncatus) feeding on several numerically abundant fish species, which in turn feed on other fish and primary producing plants and algae present in St. George Sound, FL, USA. Finally, we discuss extensions from other work that apply to this model and three important general ecological applications. Online supplementary materials include data, OpenBUGS scripts, and simulation details.

海南岛清澜-八门湾潟湖潮汐水动力的模拟研究

基于DELFT3D模型研究了清澜-八门湾潟湖的水位分布和潮汐波内部结构,以及由于人类开垦引起的海岸线变化(以1962年、1985年和2008年为例)对潟湖水动力特性的影响。结果表明,清澜-八门湾潟湖潮汐是由多种分潮耦合而成的复杂驻波,其中K_1,O_1,M_2,S_2和M_4分潮的影响最大。由湾外向湾内传输,由于湾内红树林和浅滩引起的底部损耗增加,M_2,S_2,K_1和O_1分潮幅值减弱;M_4分潮幅值增强,表现出明显的浅水增幅效应;M_2和S_2分潮相位在文教河和文昌江领域表现出明显的干湿效应。不同年代海岸线的研究表明,1985年和2008年间,人类复垦导致潟湖及其潮汐汊道附近的红树林和滩涂区域严重破坏,海岸线缩减,引发了水位降低、纳潮量减少和潟湖潮汐汊道底摩擦弱化,从而削弱了干湿、潮呛和浅水效应。后果提示持续的人类复垦活动将会引发清澜-八门湾潮汐水动力环境的进一步恶化,可能导致未来发生更大的自然灾害。

RADIATION BOUNDARY CONDITIONS FOR MAXWELL'S EQUATIONS:A REVIEW OF ACCURATE TIME-DOMAIN FORMULATIONS

We review time-domain formulations of radiation boundary conditions for Maxwell＇s equations, focusing on methods which can deliver arbitrary accuracy at acceptable compu-tational cost. Examples include fast evaluations of nonlocal conditions on symmetric and general boundaries, methods based on identifying and evaluating equivalent sources, and local approximations such as the perfectly matched layer and sequences of local boundary conditions. Complexity estimates are derived to assess work and storage requirements as a function of wavelength and simulation time.

Stable Isotope Sourcing Using Sampling

Stable isotope mixing models are used to estimate proportional contributions of sources to a mixture, such as in the analysis of animal diets, plant nutrient use, geochemistry, pollution, and forensics. We describe an algorithm implemented as SISUS software for providing a user-specified number of probabilistic exact solutions derived quickly from the extended mixing model. Our method outperforms IsoSource [1], a deterministic algorithm for providing approximate solutions to represent the solution polytope. Our method is an approximate Bayesian large sample procedure. SISUS software is freely available at StatAcumen.com/sisus and as an R package at cran.r-project.org/web/packages/sisus.

IMEX Evolution of Scalar Fields on Curved Backgrounds

Inspiral of binary black holes occurs over a time-scale of many orbits,far longer than the dynamical time-scale of the individual black holes.Explicit evolutions of a binary system therefore require excessively many time-steps to capture interesting dynamics.We present a strategy to overcome the Courant-Friedrichs-Lewy condition in such evolutions,one relying on modern implicit-explicit ODE solvers and multidomain spectral methods for elliptic equations.Our analysis considers the model problem of a forced scalar field propagating on a generic curved background.Nevertheless,we encounter and address a number of issues pertinent to the binary black hole problem in full general relativity.Specializing to the Schwarzschild geometry in KerrSchild coordinates,we document the results of several numerical experiments testing our strategy.

Structure-Preserving Finite-Element Schemes for the Euler-Poisson Equations

We discuss structure-preserving numerical discretizations for repulsive and attractive Euler-Poisson equations that find applications in fluid-plasma and selfgravitation modeling.The scheme is fully discrete and structure preserving in the sense that it maintains a discrete energy law,as well as hyperbolic invariant domain properties,such as positivity of the density and a minimum principle of the specific entropy.A detailed discussion of algorithmic details is given,as well as proofs of the claimed properties.We present computational experiments corroborating our analytical findings and demonstrating the computational capabilities of the scheme.

Generalised variance functions for longitudinal survey data

In this research, we propose longitudinal generalised variance functions (LGVFs) to produceconvenient estimates of variances by incorporating time effect into modelling. Asymptoticproperties of some certain type of estimators are investigated. Simulation studies and implementation of the proposed methods to Current Population Survey (CPS) data show that LGVFswork well in producing standard error estimates.