bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiple minima hypersurfaces studies of aluminosilicate hydration
Authors: Pérez‐Badell Yoana , Montero Luis A. 
Published: August 2009

AbstractHydrothermal zeolite synthesis is a complex process that is difficult to analyze experimentally. In this work, the role of water as solvent on the formation of aluminate and aluminosilicate clusters is described by quantum chemical calculations. The multiple minima hypersurfaces approach was used. It combines quantum chemical Hamiltonians for the calculation of the internal energy with statistical modeling and formulae for the calculation of thermodynamic functions of association. The structures of most probable hydration clusters are proposed and some of their association properties are calculated. Ab initio and semiempirical calculations of the structures and relevant reactions of aluminate and aluminosilicate fragments were reported. The results could be employed for an interpretation of the aluminosilicate synthesis. Calculations demonstrate the importance of considering other than the deepest minimum structures, giving a significant role to consider entropy of association. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Directed mechanical motion in nonequilibrium nanosystems: Occurrence conditions and kinematic controllability
Authors: Dekhtyar Marina L. , Korochkova Taisiya Ye. , Rozenbaum Viktor M. 
Published: August 2009

AbstractThe directed mechanical motion of nanoscale objects along a phase boundary can result from strongly nonequilibrium processes, which transfer the energy of various external sources to the system. This effect is particularly relevant in Brownian (molecular or biological) motors known for their high efficiency of chemical‐to‐kinetic energy conversion. Here, we formulate the necessary conditions for nanoparticle surface‐parallel motion to occur under the action of external nonequilibrium fluctuations of various nature; the ways to provide such conditions are also considered. As shown, the magnitude and sign of the average directed velocity are dictated by the competition between the spatial and temporal asymmetry of the potential energy. The theoretical models are exemplified by high‐efficiency Brownian nanoengines, molecular pumps, dipole rotators, and photo‐induced molecular motors. The latter serve to illustrate the kinematic controllability of motors by varying their molecular structure and photoexcitation parameters. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010
Accurate environmental bioindication in floodplains in spite of an extreme flood event
Authors: Follner Klaus , Hofacker Anke , Glaeser Judith , Dziock Frank , Gerisch Michael , Foeckler Francis , Ilg Christiane , Schanowski Arno , Scholz Mathias , Henle Klaus 
Published: August 2009

AbstractThe ecological reaction of species on environmental factors can differ both, temporally and geographically. Therefore, bioindicator systems must be shown to remain accurate at different places and points of time. Extreme events pose challenges for testing this robustness, which has not yet been explored systematically. The unique opportunity of the extreme flooding of the river Elbe in August 2002 was used for such a test. The bioindicator system for mean groundwater depth during the vegetation period and annual duration of inundation in floodplains studied here was developed with data collected in 1999. Data from 2003 were used to analyse the dependence of the bioindication results on the humidity of the study plots and taxonomic group (plants, molluscs and carabid beetles). For the duration of inundation, the accuracy of bioindication in 2003 was similar to that in 1999, except for the medium‐humid and dry plots using molluscs as indicators. For groundwater depth, the accuracy of bioindication in 2003 was similar to that of the reference year except in the dry plots with significantly lower accuracy for all species groups. With a few exceptions, the bioindicator system is shown to be robust and to remain accurate in spite of an extreme flood event. In conclusion, the relevance of extreme events for the robustness of bioindicator systems differs between the indicated parameters and taxonomic groups. The results stress the need to take into account the limits of the working range and the occurrence of extreme events, when testing and applying bioindicator systems. Copyright © 2009 John Wiley & Sons, Ltd.
Error analysis and regression mode of the V‐grooved sample in the atomic force microscope simulation measurement mode by the molecular mechanics
Authors: Lin Zone‐Ching , Huang Jen‐Ching , Yeh Chun‐Hui 
Published: August 2009

AbstractBased on the molecular mechanics, this study uses the two‐body potential energy function to construct a trapezoidal cantilever nano‐scale simulation measurement model of contact mode atomic force microscopy (AFM) under the constant force mode to simulate the measurement the nano‐scale V‐grooved standard sample. We investigate the error of offset distance of the cross‐section profile when using the probes with different trapezoidal cantilever probe tip radii (9.5, 8.5, and 7.5 Å) to scan the peak of the V‐grooved standard sample being reduced to one‐tenth (1/10) of its size, and use the offset error to inversely find out the regression equation. We analyze how the tip apex as well as the profile of the tip edge oblique angle and the oblique edge angle affects the offset distance. Furthermore, a probe with a larger radius of 9.5 nm is used to simulate and measure the offset error of scan curve, and acquire the regression equation. By the conversion proportion coefficient of size (ω), and revising the size‐reduced regression equation during the small size scale, a revised regression equation of a larger size scale can be acquired. The error is then reduced, further enhancing the accuracy of the AFM scanning and measurement. SCANNING 31: 147–159, 2009. © 2009 Wiley Periodicals, Inc.
Interval estimation for the difference in paired areas under the ROC curves in the absence of a gold standard test
Authors: Hsieh Hsin‐Neng , Su Hsiu‐Yuan , Zhou Xiao‐Hua 
Published: August 2009

AbstractReceiver operating characteristic (ROC) curves can be used to assess the accuracy of tests measured on ordinal or continuous scales. The most commonly used measure for the overall diagnostic accuracy of diagnostic tests is the area under the ROC curve (AUC). A gold standard (GS) test on the true disease status is required to estimate the AUC. However, a GS test may sometimes be too expensive or infeasible. Therefore, in many medical research studies, the true disease status of the subjects may remain unknown. Under the normality assumption on test results from each disease group of subjects, using the expectation‐maximization (EM) algorithm in conjunction with a bootstrap method, we propose a maximum likelihood‐based procedure for the construction of confidence intervals for the difference in paired AUCs in the absence of a GS test. Simulation results show that the proposed interval estimation procedure yields satisfactory coverage probabilities and interval lengths. The proposed method is illustrated with two examples. Copyright © 2009 John Wiley & Sons, Ltd.
A semi‐parametric threshold regression analysis of sexually transmitted infections in adolescent women
Authors: Yu Zhangsheng , Tu Wanzhu , Lee Mei‐Ling Ting 
Published: August 2009

AbstractTime‐to‐event analysis of sexually transmitted infection data is often complicated by the existence of nonproportional hazards and nonlinear independent variable effects. Methods without the proportional hazards assumption, such as threshold regression models, have been successfully used in many applications. This paper seeks to extend the existing threshold regression models to accommodate the nonlinear independent variable effects. Specifically, we incorporated penalized and regression splines to the threshold regression models for added modeling flexibility. Cross validation methods were used for the selection of the number of knots and for the determination of smoothing parameters. Variance estimates were proposed for inference purposes. Simulation results showed that the proposed methods were able to achieve nonparametric function and parametric coefficient estimates that are close to their true values. Simulation also demonstrated satisfactory performance of variance estimates. Using the proposed methods, we analyzed time from sexual debut to the first infection withChlamydia trachomatisinfection in a group of young women. Analysis shows that the lifetime number of sexual partners has a nonlinear effect on the risk ofC. trachomatisinfection and the infection risks were differential by ethnicity and age of sexual debut. Copyright © 2009 John Wiley & Sons, Ltd.
A conditional sequential sampling procedure for drug safety surveillance
Authors: Li Lingling 
Published: August 2009

AbstractWe propose a practical group sequential method, a conditional sequential sampling procedure, to test if a drug of interest (D) leads to an elevated risk for an adverse event E compared with a comparison drug C. The method is designed for prospective drug safety surveillance studies, in which, for each considered drug, a summary table with the exposed person‐times and the associated numbers of adverse events summed by strata defined by several potential confounders, is collected and updated periodically using the health plans' administrative claims data. This new approach can be applied to test for elevated relative risk whenever the data are updated. Our approach adjusts for multiple testing to preserve the overall type I error with any specified α‐spending function. Furthermore, it automatically adjusts for temporal trend and population heterogeneity across strata by conditioning on the numbers of adverse events within each stratum during each time period. Therefore, this approach is very flexible and applies to a wide class of settings. We conduct a simulation study to evaluate its performance under various scenarios. The approach is also applied to an example to examine if Rofecoxib leads to an increased relative risk for acute myocardial infraction (AMI) compared with its two counterparts Diclofenac and Naproxen, respectively. We end with discussions. Copyright © 2009 John Wiley & Sons, Ltd.
Bayesian analysis of a matched case–control study with expert prior information on both the misclassification of exposure and the exposure–disease association
Authors: Liu Juxin , Gustafson Paul , Cherry Nicola , Burstyn Igor 
Published: August 2009

AbstractWe propose a Bayesian adjustment for the misclassification of a binary exposure variable in a matched case–control study. The method admits a priori knowledge about both the misclassification parameters and the exposure–disease association. The standard Dirichlet prior distribution for a multinomial model is extended to allow separation of prior assertions about the exposure–disease association from assertions about other parameters. The method is applied to a study of occupational risk factors for new‐onset adult asthma. Copyright © 2009 John Wiley & Sons, Ltd.
An improved test of latent‐variable model misspecification in structural measurement error models for group testing data
Authors: Huang Xianzheng 
Published: August 2009

AbstractWe consider structural measurement error models for group testing data. Likelihood inference based on structural measurement error models requires one to specify a model for the latent true predictors. Inappropriate specification of this model can lead to erroneous inference. We propose a new method tailored to detect latent‐variable model misspecification in structural measurement error models for group testing data. Compared with the existing diagnostic methods developed for the same purpose, our method shows vast improvement in the power to detect latent‐variable model misspecification in group testing design. We illustrate the implementation and performance of the proposed method via simulation and application to a real data example. Copyright © 2009 John Wiley & Sons, Ltd.
Using frameworks to develop a distributed conferencing system: an experience report
Authors: Calefato Fabio , Lanubile Filippo 
Published: August 2009

AbstractApplication frameworks are a powerful means to reduce software development costs while improving quality. However, at the same time they are difficult to select and understand, as well as hard to learn, use, and debug effectively and efficiently. In this paper we report the story of eConference, a distributed conferencing system that was developed as part of a broader research effort. Here we discuss the lessons learned from the evolution of our conferencing tool over four generations, which have been necessary to find good frameworks and build a flexible distributed tool. Copyright © 2009 John Wiley & Sons, Ltd.
Netzwerkbildung aus Planquadraten und Tetraedern am Beispiel polynärer Palladiumphosphate MPd2(PO4)2 (M = Ca, Cd, Hg), MPdP2O7 (M = Ca, Sr, Ba, Zn, Hg, Pb) und PbPdSi(P2O7)21)[1]
Authors: Panagiotidis Kosta , Hoffbauer Wilfried , Glaum Robert 
Published: August 2009

AbstractStarting from PdO, HgO and P4O10 yellow, plate‐like single crystals of HgPdP2O7 were obtained by chemical vapour transport experiments (600 °C → 500 °C, addition of PdCl2). Micro‐crystalline PbPdP2O7 is synthesized by heating (Tmax = 700 °C) stoichiometric amounts of PdO, PbO, and phosphoric acid. Using chemical vapour transport experiments (800 °C → 700 °C, addition of PdCl2) brown plate‐like single crystals of PbPdP2O7 were obtained besides yellow needles of PbPdSi(P2O7)2. Brown, prismatic crystals of HgPd2(PO4)2 with edge‐lengths up to 1 mm were grown by solvothermal reactions of PdO and HgO with conc. H3PO4 (400 °C, 7d, cooling: 1°/h). The structures of all compounds were determined and refined from X‐ray single crystal data (HgPdP2O7: C2/c, a = 14.117(2) Å, b = 4.884(1) Å, c = 8.802(1) Å, β = 100.9(1)°; PbPdP2O7: Pnma, a = 13.440(1) Å, b = 5.966(1) Å, c = 7.368(1) Å; PbPdSi(P2O7)2: P21/m, a = 4.593(1) Å, b = 17.169(1) Å, c = 6.435(1) Å, β = 101.71(1)°; HgPd2(PO4)2: Fddd, a = 6.955(1) Å, b = 11.342(1) Å, c = 15.840(1) Å). According to IP Guinier‐photographs microcrystalline powders of MPd2(PO4)2 (M = Cd, Ca) and MPdP2O7 (M = Ca, Sr, Ba, Zn) are isotypic to HgPd2(PO4)2 and PbPdP2O7, respectively. 31P‐MAS‐NMR studies on HgPdP2O7 and CaPd2(PO4)2 are in accordance with one independent site for phosphorus. Their chemical shifts were determined to δiso = 24.2 , δaniso = 83.0 , η = 0.43 for HgPdP2O7 and δiso = 32.1 , δaniso = 36.0 , η = 0,84 for CaPd2(PO4)2.
Two‐Dimensional Lanthanide‐Containing Coordination Frameworks: Structure, Magnetic and Luminescence Properties
Authors: Gao Ting , Li Guang‐Ming , Yan Peng‐Fei , Zhang Ju‐Wen , Sun Wen‐Bin , Suda Masayuki , Einaga Yasuaki 
Published: August 2009

AbstractTwo lanthanide‐containing 2D coordination polymers, [Ln(H2salen)1.5(NO3)3]n [H2salen = N,N′‐ ethylenebis(salicylideneimine); Ln = Gd (1), Dy (2)], have been prepared by self‐assembly method. The molecular magnetism and luminescence of the metal complexes had been studied. Complex 1 exhibits antiferromagnetic interaction between spin carriers. Complex 2 emits the H2salen ligand luminescence.
Central neuromuscular dysfunction of the deltoid muscle in patients with chronic rotator cuff tears
Authors: Berth Alexander , Pap Géza , Neuman Wolfram , Awiszus Friedemann 
Published: August 2009

AbstractBackgroundPrevious surface electromyogram (EMG) studies have shown that chronic rotator cuff tears (RCT) may be associated with a altered activation of adjacent shoulder muscles. The effect of RCT on central neuromuscular control mechanisms of the shoulder girdle muscles such as the deltoideus muscle (DM), a key muscle of shoulder function, has as not yet been studied in detail.Materials and methodsThis study investigated the corticospinal excitability of the DM to assess the effects of RCT on the central neuromuscular function of proximal upper limb muscles. The motor-evoked potentials (MEP) in response to transcranial magnetic stimulation of DM on both sides were obtained from patients with unilateral RCT and compared with healthy control subjects.ResultsIn patients, stimulus response curves of DM demonstrated a bilateral hyperexcitability at rest and a hypoexcitability during voluntary activation (F = 3.82,P = 0.007).ConclusionsThe DM hyperexcitability may be related to alterations in the sensory output from the shoulder. The insufficient facilitation of the DM points toward a bilateral central activation deficit. These findings seem to be assigned to adaptive changes in the motor cortex as a consequence of chronic RCT, and the neuromuscular alteration of the DM should be considered when treating patients with RCT.
Autistic behavior in boys with fragile X syndrome: social approach and HPA-axis dysfunction
Authors: Roberts Jane E. , Clarke Megan A. , Alcorn Kaitlyn , Carter John C. , Long Anna C. J. , Kaufmann Walter E. 
Published: August 2009

AbstractThe primary goal of this study was to examine environmental and neuroendocrine factors that convey increased risk for elevated autistic behavior in boys with Fragile X syndrome (FXS). This study involves three related analyses: (1) examination of multiple dimensions of social approach behaviors and how they vary over time, (2) investigation of mean levels and modulation of salivary cortisol levels in response to social interaction, and (3) examination of the relationship of social approach and autistic behaviors to salivary cortisol. Poor social approach and elevated baseline and regulation cortisol are discernible traits that distinguish boys with FXS and ASD from boys with FXS only and from typically developing boys. In addition, blunted cortisol change is associated with increased severity of autistic behaviors only within the FXS and ASD group. Boys with FXS and ASD have distinct behavioral and neuroendocrine profiles that differentiate them from those with FXS alone and typically developing boys.
Synthesis and Properties of Alkylbetaine Zwitterionic Gemini Surfactants
Authors: Xie Zhanfeng , Feng Yujun 
Published: August 2009

AbstractA series of alkylbetaine zwitterionic gemini surfactants, 1,2‐bis[N‐methyl‐N‐carboxymethyl‐alkyl‐ammonium]ethane (CnAb, n = 8, 10, 12, or 14), were synthesized by alkylation of N,N′‐dimethylethylenediamine with an alkyl bromide, followed by reaction with sodium 2‐bromoacetate. Their solution properties were characterized by surface tension, steady‐state fluorescence, and rheological measurements. Surface‐tension measurements showed CnAb had lower critical micelle concentration (CMC) and higher efficiency in lowering the surface tension than their corresponding monomeric surfactants. The logCMC of CnAb decreased linearly with increasing chain lengths up to 12. Viscosity measurements showed only C10Ab could enhance aqueous solution viscosity at high concentrations.
Analysis of Cod‐Liver Oil Adulteration Using Fourier Transform Infrared (FTIR) Spectroscopy
Authors: Rohman Abdul , Che Man Yaakob B. 
Published: August 2009

AbstractAnalysis of the adulteration of cod‐liver oil with much cheaper oil‐like animal fats has become attractive in recent years. This study highlights an application of Fourier transform infrared (FTIR) spectroscopy as a nondestructive and fast technique for the determination of adulterants in cod‐liver oil. Attenuated total reflectance measurements were made on pure cod‐liver oil and cod‐liver oil adulterated with different concentrations of lard (0.5–50% v/v in cod‐liver oil). A chemometrics partial least squares (PLS) calibration model was developed for quantitative measurement of the adulterant. Discriminant analysis method was used to classify cod‐liver oil samples from common animal fats (beef, chicken, mutton, and lard) based on their infrared spectra. Discriminant analysis carried out using seven principal components was able to classify the samples as pure or adulterated cod‐liver oil based on their FTIR spectra at the selected fingerprint regions (1,500–1,030 cm−1).
A 7‐year follow‐up of multidisciplinary rehabilitation among chronic neck and back pain patients. Is sick leave outcome dependent on psychologically derived patient groups?
Authors: Bergström Gunnar , Bergström Cecilia , Hagberg Jan , Bodin Lennart , Jensen Irene 
Published: August 2009

ABSTRACTA valid method for classifying chronic pain patients into more homogenous groups could be useful for treatment planning, that is, which treatment is effective for which patient, and as a marker when evaluating treatment outcome. One instrument that has been used to derive subgroups of patients is the Multidimensional Pain Inventory (MPI). The primary aim of this study was to evaluate a classification method based on the Swedish version of the MPI, the MPI‐S, to predict sick leave among chronic neck and back pain patients for a period of 7 years after vocational rehabilitation. As hypothesized, dysfunctional patients (DYS), according to the MPI‐S, showed a higher amount of sickness absence and disability pension expressed in days than adaptive copers (AC) during the 7‐years follow‐up period, even when adjusting for sickness absence prior to rehabilitation (355.8days, 95% confidence interval, 71.7; 639.9). Forty percent of DYS patients and 26.7% of AC patients received disability pension during the follow‐up period. However, this difference was not statistically significant. Further analyses showed that the difference between patient groups was most pronounced among patients with more than 60days of sickness absence prior to rehabilitation. Cost‐effectiveness calculations indicated that the DYS patients showed an increase in production loss compared to AC patients. The present study yields support for the prognostic value of this subgroup classification method concerning long‐term outcome on sick leave following this type of vocational rehabilitation.
Quantitative reconstruction of Holocene precipitation changes in southern Patagonia
Authors: Tonello Marcela Sandra , Mancini Maria Virginia , Seppä Heikki 
Published: August 2009

AbstractHolocene variations in annual precipitation (Pann) were reconstructed from pollen data from southern Argentinian Patagonia using a transfer function developed based on a weighted-averaging partial least squares (WA-PLS) regression. The pollen–climate calibration model consisted of 112 surface soil samples and 59 pollen types from the main vegetation units, and modern precipitation values obtained from a global climate database. The performance (r2 = 0.517; RMSEP = 126 mm) of the model was comparable or slightly lower than in other comparable pollen–climate models. Fossil pollen data were obtained from a sediment core from Cerro Frias site (50°24'S, 72°42'W) located at the forest-steppe ecotone. Reconstructed Pann values of about 200 mm suggest dry conditions during the Pleistocene–Holocene transition (12,500–10,500 cal yr BP). Pann values were about 300–350 mm from 10,500 to 8000 cal yr BP and increased to 400–500 mm between 8000 and 1000 cal yr BP. An abrupt decrease in Pann at about 1000 cal yr BP was associated with a Nothofagus decline. The reconstructed Pann suggests a weakening and southward shift of the westerlies during the early Holocene and intensification, with no major latitudinal shifts, during the mid-Holocene at high latitudes in southern Patagonia.