Results 1  50 of 1824  
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Okuda Hidekazu H Research Institute for Science and Engineering, Waseda University, Tokyo,   2014
Eumelanin is a brownblack pigment comprising 5,6dihydroxyindole (DHI) and its 2carboxy derivative (DHICA), but the detailed structure of eumelanin is unclear. Chemical degradation is a powerful tool for analyzing melanin. H2 O2 oxidation degradation of eumelanin affords pyrrole2,3,5tricarboxylic acid (PTCA) and pyrrole2,3dicarboxylic acid (PDCA). The ratio of PDCA to PTCA ...


Hill Tammy   2013
Data from a probability sample were used to estimate wetland and stream mitigation success from 2007 to 2009 across North Carolina (NC). "Success" was defined as whether the mitigation site met regulatory requirements in place at the time of construction. Analytical results were weighted by both component counts and mitigation ...


Tang Kenneth   2011
OBJECTIVE: The Work Instability Scale for Rheumatoid Arthritis (RAWIS) is a promising prognostic tool for future work disability outcomes. Rasch analysis was conducted to examine the psychometric performance of the RAWIS in workrelated upper limb disorders. STUDY DESIGN AND SETTING: Eligible injured workers (n=396) attending a Shoulder and Elbow Specialty ...


Logan Brent R   2011
Many timetoevent studies are complicated by the presence of competing risks and by nesting of individuals within a cluster, such as patients in the same center in a multicenter study. Several methods have been proposed for modeling the cumulative incidence function with independent observations. However, when subjects are clustered, one ...


Chen WenYen   2011
Spectral clustering algorithms have been shown to be more effective in finding clusters than some traditional algorithms, such as kmeans. However, spectral clustering suffers from a scalability problem in both memory use and computational time when the size of a data set is large. To perform clustering on large data ...


Warton David I   2011
Summary A modification of generalized estimating equations (GEEs) methodology is proposed for hypothesis testing of highdimensional data, with particular interest in multivariate abundance data in ecology, an important application of interest in thousands of environmental science studies. Such data are typically counts characterized by high dimensionality (in the sense that ...


Luo Xianghua   2011
The gap times between recurrent events are often of primary interest in medical and epidemiology studies. The observed gap times cannot be naively treated as clustered survival data in analysis because of the sequential structure of recurrent events. This paper introduces two important building blocks, the averaged counting process and ...


Siwek M   2011
Genetic structure and relationship amongst the main goat populations in Sicily (Girgentana, Derivata di Siria, Maltese and Messinese) were analysed using information from 19 microsatellite markers genotyped on 173 individuals. A posterior Bayesian approach implemented in the program STRUCTURE revealed a hierarchical structure with two clusters at the first level ...


Calzado Carmen J   2011
This works tries to establish the performance of truncated CI calculations on the evaluation of magnetic coupling parameters with respect to available FCI estimates on a set of carbonberyllium clusters. First, second and thirdneighbor magnetic coupling constants have been evaluated and many body effective parameters as the cyclic terms. They ...


Hutmacher Matthew M   2011
Continuous bounded outcome data are unlikely to meet the usual assumptions for mixedeffects models of normally distributed and independent subjectspecific and residual random effects. Additionally, overly complicated model structures might be necessary to account adequately for nondrug (timedependent) and drug treatment effects. A transformation strategy with a likelihood component for ...


Hutmacher Matthew M   2011
Continuous bounded outcome data are unlikely to meet the usual assumptions for mixedeffects models of normally distributed and independent subjectspecific and residual random effects. Additionally, overly complicated model structures might be necessary to account adequately for nondrug (timedependent) and drug treatment effects. A transformation strategy with a likelihood component for ...


Kim YangJin   2010
Intervalcensored data are commonly found in studies of diseases that progress without symptoms, which require clinical evaluation for detection. Several techniques have been suggested with independent assumption. However, the assumption will not be valid if observations come from clusters. Furthermore, when the cluster size relates to response variables, commonly used ...


Zhang Jian   2010
Summary Clustering is a widely used method in extracting useful information from gene expression data, where unknown correlation structures in genes are believed to persist even after normalization. Such correlation structures pose a great challenge on the conventional clustering methods, such as the Gaussian mixture (GM) model, kmeans (KM), and ...


Yuan KeHai   2010
This article introduces two simple scatter plots for model diagnosis in structural equation modeling. One plot contrasts a residualbased Mdistance of the structural model with the Mdistance for the factor score. It contains information on outliers, good leverage observations, bad leverage observations, and normal cases. The other plot contrasts the ...


Teerenstra Steven   2010
Cluster randomized trials in health care may involve three instead of two levels, for instance, in trials where different interventions to improve quality of care are compared. In such trials, the intervention is implemented in health care units ("clusters") and aims at changing the behavior of health care professionals working ...


Li Xiangzhu   2010
The concept of Cconditions, originally introduced in the framework of the multireference (MR), generalmodelspace (GMS), stateuniversal (SU), coupledcluster (CC) approach with singles and doubles (GMSSUCCSD) to account for the internal amplitudes that vanish in the case of a complete model space, is applied to a stateselective or statespecific Mukherjee MRCC ...


Ip Edward H   2011
Designing cluster randomized trials in clinical studies often requires accurate estimates of intraclass correlation, which quantifies the strength of correlation between units, such as participants, within a cluster, such as a practice. Published ICC estimates, even when available, often suffer from the problem of wide confidence intervals. Using data from ...


Chen Qingfeng   2011
Many clustering approaches have been developed for biological data analysis, however, the application of traditional clustering algorithms for RNA structure data analysis is still a challenging issue. This arises from the existence of complex secondary structures while clustering. One of the most critical issues of cluster analysis is the development ...


Segal Mark R   2011
Methods for formally evaluating the clustering of events in space or time, notably the scan statistic, have been richly developed and widely applied. In order to utilize the scan statistic and related approaches, it is necessary to know the extent of the spatial or temporal domains wherein the events arise. ...


Stephenson L T   2010
A limiting characteristic of the atomprobe technique is the nondetection of ions and this embodies a significant "missing information" problem in investigations of atomic clustering phenomena causing difficulty in the interpretation of any atomprobe experiment. It is shown that the measurable clustersize distribution can be modeled by a mixed binomial ...


Lex Alexander   2010
When analyzing multidimensional, quantitative data, the comparison of two or more groups of dimensions is a common task. Typical sources of such data are experiments in biology, physics or engineering, which are conducted in different configurations and use replicates to ensure statistically significant results. One common way to analyze this ...


He Zhaoshui   2010
Recently, there has been a growing interest in multiway probabilistic clustering. Some efficient algorithms have been developed for this problem. However, not much attention has been paid on how to detect the number of clusters for the general nway clustering (n ≥ 2). To fill this gap, this problem is ...


Li Qing   2010
Multilevel analytical techniques are being applied in condom use research to ensure the validity of investigation on environmental/structural influences and clustered data from venuebased sampling. The literature contains reports of consistent associations between perceived gatekeeper support and condom use among entertainment establishmentbased female sex workers (FSWs) in Guangxi, China. However, ...


Nardelli A   2011
The Scalar RelativisticZero Order Regular ApproximationTime Dependent Density Functional Theory has been employed to study the sulfur Ledge XANES spectrum of the [Au(25)(SCH(3))(18)](+) model cluster, with the aim to reproduce and rationalize previous experimental data. The salient experimental features are properly described by the present calculation. The model cluster contains ...


Mahadevi A Subha   2010
An exhaustive study on the clusters of benzene (Bz)(n), n = 28, at MP2/631++G(∗∗) level of theory is reported. The relative strengths of CHπ and ππ interactions in these aggregates are examined, which eventually govern the pattern of cluster formation. A linear scaling method, viz., molecular tailoring approach (MTA), is ...


Oleksy Karel   2010
Equilibrium geometries and dissociation energies of He(N)(+) clusters have been calculated for N=335 using an extended genetic algorithm approach and a semiempirical model of intracluster interactions [P. J. Knowles, J. N. Murrell, and E. J. Hodge, Mol. Phys. 85, 243 (1995)]. A general aufbau principle is formulated for both ionic ...


Taylor Leslie   2011
Encouragement design studies are particularly useful for estimating the effect of an intervention that cannot itself be randomly administered to some and not to others. They require a randomly selected group receive extra encouragement to undertake the treatment of interest, where the encouragement typically takes the form of additional information ...


Viviani Roberto   2011
This study investigates the emergence of characteristic patterns in clusters thresholded at uncorrected significance levels, using as a case study rest perfusion images obtained with the continuous arterial spin labelling technique (CASL). The origin of these patterns is traced back to the existence of largescale spatial covariance, a violation of ...


Guo Yuchun   2010
Clusters of proteinDNA interaction events involving the same transcription factor are known to act as key components of invertebrate and mammalian promoters and enhancers. However, detecting closely spaced homotypic events from ChIPSeq data is challenging because random variation in the ChIP fragmentation process obscures event locations. The Genome Positioning System ...


Guevara P   2011
This paper presents a clustering method that detects the fiber bundles embedded in any MRdiffusion based tractography dataset. Our method can be seen as a compressing operation, capturing the most meaningful information enclosed in the fiber dataset. For the sake of efficiency, part of the analysis is based on clustering ...


SalimiKhorshidi Gholamreza G Centre for Functional MRI of the Brain (FMRIB), University of Oxford, Oxford, UK.   2011
In nonstationary images, cluster inference depends on the local image smoothness, as clusters tend to be larger in smoother regions by chance alone. In order to correct the inference for such nonstationary, cluster sizes can be adjusted according to a local smoothness estimate. In this study, adjusted cluster sizes are ...


Covariate adjusted weighted normal spatial scan statistics with applications to study geographic ...
Huang Lan   2010
In the field of cluster detection, a weighted normal modelbased scan statistic was recently developed to analyze regional continuous data and to evaluate the clustering pattern of predefined cells (such as state, county, tract, school, hospital) that include many individuals. The continuous measures of interest are, for example, the survival ...


Rodríguez Galdón Beatriz B Department of Analytical Chemistry, Food Science and Nutrition, University of La Laguna, Avenida Astrofísico Francisco Sánchez s/n, 38201 La Laguna, Santa Cruz de Tenerife,   2010
Eight cultivars of different colored onions (white, golden, and red) were evaluated for fresh bulbs cultivated and grown under the same environmental and agronomical conditions. Cluster analysis and principal component analysis, based on different flavonoids, total phenols, and pungency, data showed that the onions were not clustered according to variety ...


Wang Zhi Min   2010
This brief presents a curve clustering technique based on a new multivariate model. Instead of the usual Gaussian random effect model, our method uses the multivariate tdistribution model which has better robustness to outliers and noise. In our method, we use the Bspline curve to model curve data and apply ...


Zheng Xiujuan   2011
Tracer kinetic modeling with dynamic positron emission tomography (PET) requires a plasma timeactivity curve (PTAC) as an input function. Several imagederived input function (IDIF) methods that rely on drawing the region of interest (ROI) in large vascular structures have been proposed to overcome the problems caused by the invasive approach ...


Wu Xiaoru   2011
Detecting data fabrication is of great importance in clinical trials. As the role of statisticians in detecting abnormal data patterns has grown, a large number of statistical procedures have been developed, most of which are based on descriptive statistics. Based upon the fact that substantial data fabrication cases have certain ...


Tzortzis Grigorios F   2010
Multiview clustering partitions a dataset into groups by simultaneously considering multiple representations (views) for the same instances. Hence, the information available in all views is exploited and this may substantially improve the clustering result obtained by using a single representation. Usually, in multiview algorithms all views are considered equally important, ...


Wright Mark H   2010
The development of new highthroughput genotyping products requires a significant investment in testing and training samples to evaluate and optimize the product before it can be used reliably on new samples. One reason for this is current methods for automated calling of genotypes are based on clustering approaches which require ...


Sow T M A   2010
This study identified the sensory characteristics and consumer preference for chicken meat in Guinea. Five chicken samples [live village chicken, live broiler, live spent laying hen, readytocook broiler, and readytocook broiler (imported)] bought from different locations were assessed by 10 trained panelists using 19 sensory attributes. The ANOVA results showed ...


Spruyt Karen   2010
To classify pediatric sleep disordered breathing (SDB) using unbiased approaches. In children, decisions regarding severity and treatment of SDB are conducted solely based on empirical observations. Although recognizable entities clearly exist under the SDB spectrum, neither the number of SDB categories nor their specific criteria have been critically defined. Retrospective ...


Gangnon Ronald E   2010
Maps of estimated disease rates over multiple time periods are useful tools for gaining etiologic insights regarding potential exposures associated with specific locations and times. In this paper, we describe an extension of the GangnonClayton model for spatial clustering to spatiotemporal data. As in the purely spatial model, a large ...


Schwämmle Veit   2010
Fuzzy cmeans clustering is widely used to identify cluster structures in highdimensional datasets, such as those obtained in DNA microarray and quantitative proteomics experiments. One of its main limitations is the lack of a computationally fast method to set optimal values of algorithm parameters. Wrong parameter values may either lead ...


Parkhill John A   2010
Paired, activespace treatments of static correlation are augmented with additional amplitudes to produce a hierarchy of parsimonious and efficient cluster truncations that approximate the total energy. The number of parameters introduced in these models grow with system size in a tractable way: two powers larger than the static correlation model ...


Wang Yongtao   2011
In this paper, we present a robust and efficient approach to extract motion layers from a pair of images with large disparity motion. First, motion models are established as: 1) initial SIFT matches are obtained and grouped into a set of clusters using our developed topological clustering algorithm; 2) for ...


Philippe Thomas   2010
Local magnification effects and trajectory overlaps related to the presence of a second phase (clusters) are key problems and still open issues in the assessment of quantitative composition data in threedimensional atom probe tomography (APT) particularly for tiny soluteenriched clusters. A model based on the distribution of distance of first ...


Deckman Jason   2010
It is demonstrated how the problem of ground state estimation of an nbody system can be recast as the less demanding problem of finding the global minimum of an effective potential in the 3ndimensional coordinate space. The latter emerges when the solution of the imaginarytime Schrödinger equation is approximated by ...


He Jiankui   2010
Clustered regularly interspaced short palindromic repeats (CRISPR) in bacterial and archaeal DNA have recently been shown to be a new type of antiviral immune system in these organisms. We here study the diversity of spacers in CRISPR under selective pressure. We propose a population dynamics model that explains the biological ...


Lezcano Leonardo   2012
Clinical archetypes are modular definitions of clinical data, expressed using standard or open constraintbased data models as the CEN EN13606 and openEHR. There is an increasing archetype specification activity that raises the need for techniques to associate archetypes to support better management and user navigation in archetype repositories. This paper ...


Li Xiaoyun   2011
Summary In some biomedical studies involving clustered binary responses (say, disease status), the cluster sizes can vary because some components of the cluster can be absent. When both the presence of a cluster component as well as the binary disease status of a present component are treated as responses of ...


Reich Brian J BJ Department of Statistics, North Carolina State University, Raleigh, North Carolina 27695, USA.   2011
Identifying homogeneous groups of individuals is an important problem in population genetics. Recently, several methods have been proposed that exploit spatial information to improve clustering algorithms. In this article, we develop a Bayesian clustering algorithm based on the Dirichlet process prior that uses both genetic and spatial information to classify ...


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