bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Cohort Study to Assess the Impact of Depression on Patients with Kidney Disease
Authors: Zimmermann Paulo Roberto , Camey Suzi Alves , De Jesus Mari Jair 
Published: January 2007

Aims: This study assessed the impact of depression on mortality and quality of life of patients with kidney disease. Material: This study was conducted at Hospital São Lucas of Pontificia Universidade Católica of Rio Grande do Sul, Porto Alegre, Brazil, with a cohort of 125 patients seen from 1996 to 2004 (mean follow-up=77.6 months). Patients undergoing renal replacement therapy were asked to fill in the Beck Depression Inventory (BDI). At the completion of follow-up, 72 patients were alive, and 56 answered the BDI and the Medical Outcome Study Short Form General Health Survey (SF-36) to assess quality of life. Main outcome measures were mortality and quality of life. Results: Initial analysis showed that mortality was associated with age, treatment modality—continuous ambulatory peritoneal dialysis (CAPD) or hemodialysis (hd)—and depression. When controlling for age, gender, depression, and treatment modality in a multiple regression analysis, transplantation (tx), gender and age was associated with lower mortality. However, levels of depression at the end of follow-up were strongly associated with quality of life. Conclusions: Depression was not associated with mortality of patients with kidney disease when controlling for gender, age, and treatment modality. Transplantation was the main factor associated with lower mortality. Depression was, however, a strong predictor of quality of life. Number of depressive symptoms was directly associated with lower quality of life in most of the items of the SF-36.
Quality of Life and Associated Factors among Adults with Epilepsy in Nigeria
Authors: Mosaku Kolawole S. , Fatoye Femi O. , Komolafe Morenikeji , Lawal Musiliu , Ola Bola A. 
Published: January 2007

Objective: Epilepsy is a common condition worldwide and has been observed to affect quality of life (QOL). Though, much has been written on this subject among western populations, little research has been done in developing countries of Africa including Nigeria. The study aims to identify factors associated with quality of life among adult epilepsy patients in this environment. Method: Respondents were evaluated using the 10-item Quality of Life in Epilepsy Inventory (QOLIE-10), the 30-item General Health Questionnaire (GHQ-30), the modified Mini Mental State Examination (mMMSE), and the Hospital Anxiety and Depression Scale (HADS). Diagnosis of epilepsy was based on clinical and electroencephalographic findings. Results: The mean age of the 51 respondents was 27.7years ( SD = 9.7). Thirteen (25.5%) had an average of 2 seizure episodes in the month preceding the interview, while 37 (72.5%) have had the condition for more than 5 years. Factors that were significantly associated with overall quality of life included being female ( p < 0.05), seizure frequency ( p < 0.01), using more than 1 anti-epileptic drugs (AEDs) ( p < 0.01), GHQ-30 score ( p < 0.01), high anxiety score ( p < 0.001), and high depression score ( p < 0.01). Multiple regression analysis showed that depressive symptoms were the single most important factor explaining low QOL. Other factors were GHQ-30 score, seizure frequency, and being a woman. Conclusion: Controlling seizures and paying attention to the psychological needs of adult epileptics will have a positive effect on the QOL among Nigerian epileptics.
On quasi‐likelihood inference in generalized linear mixed models with two components of dispersion
Authors: Sutradhar Brajendra C. , Rao R. Prabhakar 
Published: January 2007

AbstractThe authors propose a quasi‐likelihood approach analogous to two‐way analysis of variance for the estimation of the parameters of generalized linear mixed models with two components of dispersion. They discuss both the asymptotic and small‐sample behaviour of their estimators, and illustrate their use with salamander mating data.
A fast distance‐based approach for determining the number of components in mixtures
Authors: Sahu Sujit K. , Cheng Russell C. H. 
Published: January 2007

AbstractThe authors propose a procedure for determining the unknown number of components in mixtures by generalizing a Bayesian testing method proposed by Mengersen & Robert (1996). The testing criterion they propose involves a Kullback‐Leibler distance, which may be weighted or not. They give explicit formulas for the weighted distance for a number of mixture distributions and propose a stepwise testing procedure to select the minimum number of components adequate for the data. Their procedure, which is implemented using the BUGS software, exploits a fast collapsing approach which accelerates the search for the minimum number of components by avoiding full refitting at each step. The performance of their method is compared, using both distances, to the Bayes factor approach.
Simple estimation of the mode of a multivariate density
Authors: Abraham Christophe , Biau Gérard , Cadre Benoît 
Published: January 2007

AbstractThe authors consider an estimate of the mode of a multivariate probability density using a kernel estimate drawn from a random sample. The estimate is defined by maximizing the kernel estimate over the set of sample values. The authors show that this estimate is strongly consistent and give an almost sure rate of convergence. This rate depends on the sharpness of the density near the true mode, which is measured by a peak index.
Exactly optimal sampling designs for processes with a product covariance structure
Authors: Mukherjee Bhramar 
Published: January 2007

AbstractThe author considers the problem of finding exactly optimal sampling designs for estimating a second‐order, centered random process on the basis of finitely many observations. The value of the process at an unsampled point is estimated by the best linear unbiased estimator. A weighted integrated mean squared error or the maximum mean squared error is used to measure the performance of the estimator. The author presents a set of necessary and sufficient conditions for a design to be exactly optimal for processes with a product covariance structure. Expansions of these conditions lead to conditions for asymptotic optimality.
Empirical likelihood confidence regions for comparison distributions and roc curves
Authors: Claeskens Gerda , Jing Bing‐Yi , Peng Liang , Zhou Wang 
Published: January 2007

AbstractAbstract: The authors derive empirical likelihood confidence regions for the comparison distribution of two populations whose distributions are to be tested for equality using random samples. Another application they consider is to ROC curves, which are used to compare measurements of a diagnostic test from two populations. The authors investigate the smoothed empirical likelihood method for estimation in this context, and empirical likelihood based confidence intervals are obtained by means of the Wilks theorem. A bootstrap approach allows for the construction of confidence bands. The method is illustrated with data analysis and a simulation study.
Nonparametric estimation of renewal processes from count data
Authors: Guédon Yann , Cocozza‐Thivent Christiane 
Published: January 2007

AbstractAbstract: The authors address the problem of estimating an inter‐event distribution on the basis of count data. They derive a nonparametric maximum likelihood estimate of the inter‐event distribution utilizing the EM algorithm both in the case of an ordinary renewal process and in the case of an equilibrium renewal process. In the latter case, the iterative estimation procedure follows the basic scheme proposed by Vardi for estimating an inter‐event distribution on the basis of time‐interval data; it combines the outputs of the E‐step corresponding to the inter‐event distribution and to the length‐biased distribution. The authors also investigate a penalized likelihood approach to provide the proposed estimation procedure with regularization capabilities. They evaluate the practical estimation procedure using simulated count data and apply it to real count data representing the elongation of coffee‐tree leafy axes.
Loss functions for estimation of extrema with an application to disease mapping
Authors: Wright Deanne L. , Stern Hal S. , Cressie Noel 
Published: January 2007

AbstractIt is often of interest to find the maximum or near maxima among a set of vector‐valued parameters in a statistical model; in the case of disease mapping, for example, these correspond to relative‐risk “hotspots” where public‐health intervention may be needed. The general problem is one of estimating nonlinear functions of the ensemble of relative risks, but biased estimates result if posterior means are simply substituted into these nonlinear functions. The authors obtain better estimates of extrema from a new, weighted ranks squared error loss function. The derivation of these Bayes estimators assumes a hidden‐Markov random‐field model for relative risks, and their behaviour is illustrated with real and simulated data.
Local influence for generalized linear mixed models
Authors: Zhu Hong‐Tu , Lee Sik‐Yum 
Published: January 2007

AbstractThe authors describe a method for assessing model inadequacy in maximum likelihood estimation of a generalized linear mixed model. They treat the latent random effects in the model as missing data and develop the influence analysis on the basis of a Q‐function which is associated with the conditional expectation of the complete‐data log‐likelihood function in the EM algorithm. They propose a procedure to detect influential observations in six model perturbation schemes. They also illustrate their methodology in a hypothetical situation and in two real cases.
Formation of 1D Poly(3,4‐ethylenedioxythiophene) Nanomaterials in Reverse Microemulsions and Their Application to Chemical Sensors
Authors: Yoon H. , Chang M. , Jang J. 
Published: February 2007

Abstract1D poly(3,4‐ethylenedioxythiophene) (PEDOT) nanomaterials, including ellipsoidal nanoparticles, nanorods, and nanotubes, are fabricated via chemical oxidation polymerization in reverse (water‐in‐oil) microemulsions. The reverse cylindrical micelles are prepared with sodium bis(2‐ethylhexyl) sulfosuccinate (AOT) and aqueous FeCl3 solution in hexane. The morphology of the final products is determined by carefully tuning the degree of oxidation potential at the micelle surface. Notably, the fabrication of gram‐scale amounts of products is possible under optimized synthetic conditions, suggesting that this methodology is appropriate for the large‐scale production of the corresponding nanomaterials. The as‐prepared PEDOT nanomaterials are applied to the precise detection of alcohol vapors. The chemical sensors based on the PEDOT nanomaterials present excellent reversibility and reproducibility in response.
Surface‐Modified High‐k Oxide Gate Dielectrics for Low‐Voltage High‐Performance Pentacene Thin‐Film Transistors
Authors: Kim C. S. , Jo S. J. , Lee S. W. , Kim W. J. , Baik H. K. , Lee S. J. 
Published: January 2007

AbstractIn this study, pentacene thin‐film transistors (TFTs) operating at low voltages with high mobilities and low leakage currents are successfully fabricated by the surface modification of the CeO2–SiO2 gate dielectrics. The surface of the gate dielectric plays a crucial role in determining the performance and electrical reliability of the pentacene TFTs. Nearly hysteresis‐free transistors are obtained by passivating the devices with appropriate polymeric dielectrics. After coating with poly(4‐vinylphenol) (PVP), the reduced roughness of the surface induces the formation of uniform and large pentacene grains; moreover, –OH groups on CeO2–SiO2 are terminated by C6H5, resulting in the formation of a more hydrophobic surface. Enhanced pentacene quality and reduced hysteresis is observed in current–voltage (I–V) measurements of the PVP‐coated pentacene TFTs. Since grain boundaries and –OH groups are believed to act as electron traps, an OH‐free and smooth gate dielectric leads to a low trap density at the interface between the pentacene and the gate dielectric. The realization of electrically stable devices that can be operated at low voltages makes the OTFTs excellent candidates for future flexible displays and electronics applications.
Salicylaldimine Ruthenium Alkylidene Complexes: Metathesis Catalysts Tuned for Protic Solvents
Authors: Binder Joseph B. , Guzei Ilia A. , Raines Ronald T. 
Published: February 2007

AbstractTuning the electronic and steric environment of olefin metathesis catalysts with specialized ligands can adapt them to broader applications, including metathesis in aqueous solvents. Bidentate salicylaldimine ligands are known to stabilize ruthenium alkylidene complexes, as well as allow ring‐closing metathesis in protic media. Here, we report the synthesis and characterization of exceptionally robust olefin metathesis catalysts bearing both bidentate salicylaldimine and N‐heterocyclic carbene ligands, including a trimethylammonium‐functionalized complex adapted for polar solvents. NMR spectroscopy and X‐ray crystallographic analysis confirm the structures of the complexes. Although the N‐heterocyclic carbene–salicylaldimine ligand combination limits the activity of these catalysts in non‐polar solvents, this pairing enables efficient ring‐closing metathesis of both dienes and enynes in methanol and methanol/water mixtures under air.
Enantioselective Hydrogenation of N‐Acetyldehydroamino Acids over Supported Palladium Catalysts
Authors: Szöllősi György , Szabó Emese , Bartók Mihály 
Published: February 2007

AbstractThe enantioselective hydrogenation of two N‐acetyldehydroamino acids over Cinchona alkaloid‐modified, supported palladium catalysts has been studied. Moderate enantioselectivities, up to 36 %, were obtained in the hydrogenation of 2‐acetamidocinnamic acid over cinchonidine‐modified Pd/TiO2 under low hydrogen pressure. Increase in the pressure or use of benzylamine as additive led to a gradual decrease in the enantiomeric excess and eventually inversion of the sense of the enantioselectivity. On the contrary, the optical purity of the product resulting from the hydrogenation of 2‐acetamidoacrylic acid was significantly increased by addition of benzylamine to the reaction mixture. Enantiomeric excess values up to 58 % and 60 % were obtained over Pd/Al2O3 modified by cinchonidine and cinchonine, respectively. These optical purities are the best obtained in the hydrogenation of dehydroamino acid derivatives over chirally modified heterogeneous metal catalysts.
A Novel Propargylation/Cycloisomerization Tandem Process Catalyzed by a Ruthenium(II)/Trifluoroacetic Acid System: One‐Pot Entry to Fully Substituted Furans from Readily Available Secondary Propargylic Alcohols and 1,3‐Dicarbonyl Compounds
Authors: Cadierno Victorio , Gimeno José , Nebra Noel 
Published: February 2007

AbstractA simple and highly efficient method for the preparation of tetrasubstituted furans starting from readily accessible propargylic alcohols and commercially available 1,3‐dicarbonyl compounds has been developed. The process, which proceeds in a one‐pot manner, involves the initial propargylation of the 1,3‐dicarbonyl compound promoted by trifluoroacetic acid, and subsequent cycloisomerization of the resulting γ‐ketoalkyne catalyzed by the 16‐electron allyl‐ruthenium(II) complex [Ru(η3‐2‐C3H4Me)(CO)(dppf)][SbF6].
A Basic Water Quality Model for the River Neckar: Part 1 – model development, parameter sensitivity and identifiability, calibration and validation
Authors: Haag Ingo 
Published: January 2007

AbstractIn order to simulate and forecast dissolved oxygen (DO) in the central part of River Neckar, we developed a Basic Water Quality Model (BWQM). The present paper gives a comprehensive description of model development, model structure along with the governing equations, sensitivity and identifiability analyses as well as calibration and validation. The development of BWQM was guided by two major restrictions: it has to account for all relevant processes affecting DO, and it should only be based on readily available data and system knowledge. These restrictions led to a model, calculating nine state variables, including DO, phytoplankton, nutrients, and biochemical oxygen demand. However, due to limited data, the representation of phytoplankton is quite simple. A local sensitivity analysis led to a subset of five parameters, which are much more sensitive than the 22 other parameters. These five parameters are all closely connected with phytoplankton dynamics, highlighting the importance of phytoplankton for the DO budget. On the basis of an a priori identifiability analysis, four out of the five most sensitive parameters were chosen for model calibration. The calibrated model performed well in simulating DO and phytoplankton. Given the data availability and the present state of system knowledge, BWQM comes close to representing the optimal model with respect to predicting DO and phytoplankton.
Spatio‐genetic population structure in mustached tamarins, Saguinus mystax
Authors: Huck Maren , Roos Christian , Heymann Eckhard W. 
Published: February 2007

AbstractDispersal and philopatry influence gene flow and thus the spatio‐genetic structure within and between populations. In callitrichids the flexible social and mating system corresponds with a variable migration pattern where both sexes might be philopatric or might disperse. We investigated the relationship between the spatio‐genetic structure and migration patterns in a population of mustached tamarins, Saguinus mystax. Using the rapidly evolving hypervariable region I (HVI) of the mitochondrial control region and 11 microsatellite markers we detected a high variation (HVI: 16 haplotypes in 69 individuals; microsatellites: HO = 0.75, average: 7.45 alleles/locus), with mating partners usually not sharing the same haplotype, indicating that matings are generally between partners that are not closely related. Similar high variance of haplotype differences for male‐male and female‐female pairs, along with a slightly higher number of haplotype differences in males show that both sexes habitually migrate. Spatial analyses suggest that females usually migrate longer distances, corresponding to very limited breeding positions for females in a polyandrous social mating system. Am J Phys Anthropol, 2007. © 2007 Wiley‐Liss, Inc.
Thermal oxidative degradation of bicomponent PP/PET fiber during thermal bonding process
Authors: Wang X. Y. , Gong R. H. 
Published: January 2007

AbstractThe effects of the thermal bonding temperature, dwell time, and the type of mold materials on the thermal oxidative degradation of the PP sheath of bicomponent fibers were investigated using the Fourier Transform Infrared Spectra (FTIR) and Thermal Gravimetry/Differential Scanning Calorimetry (TG‐DSC) techniques. The samples were prepared on a new 3D nonwovens process based on air‐laying and through‐air thermal bonding. The fiber material was a commercial polypropylene (PP)/polyester (PET) (sheath/core) bicomponent staple fiber. The results reveal that ketone developed following β‐scission in the thermally bonded nonwovens. The level of thermal oxidative degradation increases with increase in the bonding temperature, dwell time, and the thermal conductivity of the mold material. Such thermal oxidative degradation led to the slight widening of the melting peaks of the fiber PP sheath in the thermally bonded nonwovens, and a slight decreasing of melting point compared with those of the as‐received fiber. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 391–397, 2007
Microstructural transformation of wool during stretching with tensile curves
Authors: Liu Hongling , Yu Weidong 
Published: January 2007

AbstractThe microstructural transformation of wool fiber during the stretching process was investigated by the tensile tests and TEM micrograph observation. The results showed that water breaks some of the hydrogen bonds in the fiber, whereas the sodium bisulfite solution breaks some of the disulphide crosslinks between the peptide molecules, then the wool fiber is easy to be stretched. Two types of transformations were found during the stretching process, that is, the slippage of molecule chains or microstructural elements and the α→β transformation. The α→β transformation is dominant, in particular, during the low stretching rate process. In addition, the stretching slenderization tends to increase the tenacity of wool fiber and decrease its extension at break. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 816–822, 2007
Spherical cellulose–nickel powder composite matrix customized for expanded bed application
Authors: Xia Hai‐Feng , Lin Dong‐Qiang , Yao Shan‐Jing 
Published: January 2007

AbstractExpanded bed adsorption (EBA) is an integrated technology for capturing target biomolecules directly from particle‐containing feedstock. The adsorbents are the key base to achieve the EBA process and should be designed specially. In present work a new type of composite particles for EBA application was prepared with cellulose as the skeleton, and nickel powder as the densifier through the method of water‐in‐oil suspension thermal regeneration. Two fractions of spherical particles with mean sizes of 101–119 μm and 168–217 μm were obtained and the effects of nickel powder addition on the physical properties of composite particles were analyzed. The results indicated that the cellulose–nickel powder composite particles prepared have appropriate wet density of 1.14–1.78 g/mL, water content of 51–75%, porosity of 81–93%, pore radius of 41–59 nm, and specific surface area of 30–42 m2/mL of wet particles. The bed expansion factor at the range of 2–3 was investigated and correlated with Richardson–Zaki equation. In addition, the bed stability with composite particles prepared was demonstrated with the observation of liquid mixing in expanded bed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 740–747, 2007
Kinetics of sulfur vulcanization of 1,4‐cis‐polyisoprene by differential scanning calorimetry
Authors: Kolesnikova N. N. , Ostroukhova O. A. , Popov A. A. 
Published: January 2007

AbstractThe vulcanization of 1,4‐cis‐polyisoprene was studied by differential scanning calorimetry under isothermal and nonisothermal conditions. On the basis of thermal characteristics obtained, the kinetic parameters of crosslinking (the induction period, maximum rate, and effective energy of activation) were determined. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 754–757, 2007
Surface modification and physical properties of various UHMWPE‐fiber‐reinforced modified epoxy composites
Authors: Lin S. P. , Han J. L. , Yeh J. T. , Chang F. C. , Hsieh K. H. 
Published: January 2007

AbstractTwo surface modification methods—plasma surface treatment and chemical agent treatment—were used to investigate their effects on the surface properties of ultrahigh‐molecular‐weight polyethylene (UHMWPE) fibers. In the analyses, performed using electron spectroscopy for chemical analysis, changes in weight, and scanning electron microscope observations, demonstrated that the two fiber‐surface‐modified composites formed between UHMWPE fiber and epoxy matrix exhibited improved interfacial adhesion and slight improvements in tensile strengths, but notable decreases in elongation, relative to those properties of the composites reinforced with the untreated UHMWPE fibers. In addition, three kinds of epoxy resins—neat DGEBA, polyurethane‐crosslinked DGEBA, and BHHBP‐DGEBA—were used as resin matrices to examine the tensile and elongation properties of their UHMWPE fiber‐reinforced composites. From stress/strain measurements and scanning electron microscope observations, the resin matrix improved the tensile strength apparently, but did not affect the elongation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 655–665, 2007