bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of the electron localization function to radical systems
Authors: Melin Junia , Fuentealba P. 
Published: March 2003

AbstractAn application of the topological electron localization function (ELF) analysis to free radical systems is presented. A separation of the ELF function into its α‐spin and β‐spin contributions has been performed. Methyl and phenyl radicals, ortho‐, meta‐, and para‐benzyne biradicals, and their corresponding radical anions have been chosen with the aim to validate the new ELFα and ELFβ proposed functions. The results show that the ELF separation yields complementary information about the localization of the unpaired electron. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Coupled harmonic oscillator systems: Improved algebraic decoupling approach
Authors: Burrows B. L. , Cohen M. , Feldmann Tova 
Published: March 2003

AbstractWe present a novel explicit decoupling procedure that leads to exact solutions of the Schrödinger equation forNharmonic oscillators in the presence of general bilinear perturbing potentials. This generalizes previous work, which was restricted toorthogonaltransformations with conditions imposed on the perturbing terms. It is shown that the formalism is sufficiently general to embrace bothstationary‐stateandresonance‐stateproblems and, in particular, we include exact model calculations of a free electron interacting with a lattice and a discussion of an application to an ideal ion trap. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Conformational and electronic study ofN‐phenylalkyl‐3,4‐dichloromaleimides: Ab initio and DFT study
Authors: Zamora Miguel A. , Masman Marcelo F. , Bombasaro José A. , Freile Mónica L. , Filho Valdir Cechinel , López Silvia N. , Zacchino Susana A. , Enriz Ricardo D. 
Published: March 2003

AbstractA conformational and electronic study onN‐phenylalkyl‐3,4‐dichloromaleimides, a new series of antifungal compounds, was carried out. In this study ab initio [RHF/3‐21G and RHF/6‐31G(d)] and density functional theory (B3LYP/6‐31G(d)) calculations were performed. The effect of solvent (water) was taken into account by performing calculations with the isodensity polarizable continuum model method. The electronic study of the compounds was carried out using molecular electrostatic potentials. The presence of two symmetrical aromatic systems reduces notably the conformational possibilities of these maleimides. The results permit the recognition of the minimal structural requirements for the production of the antifungal response; a 3,4‐dichloroimido ring and a benzene ring appear to be indispensable. Also, theoretical calculations suggest that the optimum interatomic distance between these moieties is about 3.5–5.0 Å. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Ionic matrices for matrix‐assisted laser desorption/ionization time‐of‐flight detection of DNA oligomers
Authors: Carda‐Broch Samuel , Berthod Alain , Armstrong Daniel W. 
Published: March 2003

AbstractSalts with low melting points, also termed room‐temperature ionic liquids, can be used as matrices in matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF). They have great vacuum stability, and can dissolve polar and apolar solutes including carbohydrates, biological oligomers and proteins. The ionic liquids give much more homogeneous sample solutions compared with solid matrices. We demonstrate the usefulness of using ionic matrices to determine the molecular weight of DNA oligomers by direct TOF mass spectrometric analysis. Three oligonucleotides were tested, (d(pT)10, d(pC)11, and d(pC)12), with several ionic matrices synthesized from different bases associated to two acids (3‐hydroxypicolinic acid and 2,5‐dihydroxybenzoic acid). The results obtained show that the best ionic matrices enhance the ion peak intensity of the oligonucleotides with respect to conventional molecular matrices under our experimental conditions. In one case, an ionic matrix provided a signal‐to‐noise ratio ten times higher than the corresponding molecular matrix. Several of the tested ionic matrices were liquids. However, all working ionic matrices were solids. Copyright © 2003 John Wiley & Sons, Ltd.
Liquid chromatography with electrospray ion‐trap mass spectrometry for the determination of anatoxins in cyanobacteria and drinking water
Authors: Furey Ambrose , Crowley Janet , Lehane Mary , James Kevin J. 
Published: March 2003

AbstractAnatoxin‐a (AN) and homoanatoxin‐a (HMAN) are potent neurotoxins produced by a number of cyanobacterial species. A new, sensitive liquid chromatography/multiple tandem mass spectrometry (LC/MSn) method has been developed for the determination of these neurotoxins. The LC system was coupled, via an electrospray ionisation (ESI) source, to an ion‐trap mass spectrometer in positive ion mode. The [M+H]+ ions at m/z 166 (anatoxin‐a) and m/z 180 (homoanatoxin‐a) were used as the precursor ions for multiple MS experiments. MS2MS4 spectra displayed major fragment ions at m/z 149 (AN), 163 (HMAN), assigned to [MNH3+H]+; m/z 131 (AN), 145 (HMAN), assigned to [MNH3H2O+H]+, and m/z 91 [C7H7]+. Although the chromatographic separation of these neurotoxins is problematic, reversed‐phase LC, using a C18 Luna column, proved successful. Calibration data for anatoxin‐a using spiked water samples (10 mL) in LC/MSn modes were: LC/MS (25–1000 μg/L), r2 = 0.998; LC/MS2 (5–1000(μg/L), r2 = 0.9993; LC/MS3 (2.5–1000 μg/L), r2 = 0.9997. Reproducibility data (% RSD, N = 3) for each LC/MSn mode ranged between 2.0 at 500 μg/L and 7.0 at 10 μg/L. The detection limit (S/N = 3) for AN was better than 0.03 ng (on‐column) for LC/MS3 which corresponded to 0.6 μg/L. Copyright © 2003 John Wiley & Sons, Ltd.
Differentiation of isomeric sulfur heterocycles by electron ionization mass spectrometry: 1,4‐dithiins, 1,4‐dithiafulvenes and their analogues tetrathianaphthalenes, tetrathiafulvalenes and tetrathiapentalenes
Authors: Garín Javier , Orduna Jesús , Royo José María , Quéré Anne‐Marie Le , Müller Harald 
Published: March 2003

AbstractThe electron ionization mass spectra of the title compounds have been studied along with the product ion spectra of their metastable or collisionally activated molecular ions. The relative abundances of ions in the spectra allow unambiguous isomer differentiation. Isomerization of the molecular ions was observed in the metastable ion spectra of tetrathianaphthalenes and tetrathiafulvalenes. This isomerization reaction parallels the electrochemical or base‐induced isomerization observed in solution. The studied tetrathiapentalene derivative does not rearrange to the corresponding tetrathiafulvalene or tetrathianaphthalene isomers. Copyright © 2003 John Wiley & Sons, Ltd.
Enantioselective trace analysis of amphetamine in human plasma by gas chromatography/negative ion chemical ionization mass spectrometry
Authors: Leis Hans‐Jörg , Rechberger Gerald N. , Fauler Günter , Windischhofer Werner 
Published: March 2003

AbstractA method for the quantitative enantioselective analysis of amphetamine in human plasma by gas chromatography/negative ion chemical ionization mass spectrometry (GC/NICI‐MS) is presented. Five‐fold deuterated analogues of both enantiomers were used as internal standard. Plasma sample preparation was performed by a rapid liquid–liquid extraction using n‐hexane. Derivatization with (S)‐(−)‐N‐(heptafluorobutyryl)prolyl chloride was accomplished directly in the n‐hexane extract to avoid loss of amphetamine during sample concentration. The method was validated in the expected concentration range of 0.006 for a pharmacokinetic study. Calibration curves were linear within a range 0.006–50 ng/mL plasma. Precision and accuracy were acceptable over the entire calibration range. Baseline separation of the enantiomers was easily achieved on a 15‐m nonchiral apolar column. The method is simple and robust, and has been applied to the batch analysis of amphetamine enantiomers. Copyright © 2003 John Wiley & Sons, Ltd.
SWI/SNF chromatin remodelling complex and retroviral gene silencing
Authors: Iba Hideo , Mizutani Taketoshi , Ito Taiji 
Published: March 2003

AbstractBecause of the unique infectious cycle of retroviruses which involves the integration of the retroviral genome into the host chromosome, many cellular chromosomal proteins are used by the virus to maintain its gene expression. At the same time, cellular mechanisms for the surveillance and exclusion of non‐self expression by such intragenomic parasites operate as an important host defence system in the cellular nuclei. Retroviruses have strategies for escaping from host defence systems, such as by maintaining or reactivating viral expression in specific host cell types. Understanding such epigenetical regulation would be essential for progress in retroviral virology. In this review, we emphasise the importance of the chromatin remodelling factor SWI/SNF complex as one of the key players in epigenetic regulation of host and viral gene expression. An understanding of these mechanisms will surely lead to new ideas on the pathogenicity of this virus, on the latent infection observed in many other viruses, and further forward the design of unique retroviral vectors for long‐term transgene expression, providing strong tools for human gene therapy and regenerative medicine. Copyright © 2003 John Wiley & Sons, Ltd.
Dynamics and Coupling Actuation of Elastic Underactuated Manipulators
Authors: Zhao Tie Shi , Dai Jian S. 
Published: March 2003

AbstractThis paper investigates the constraint and coupling characteristics of underactuated manipulators by proposing an elastic model of the manipulator and examining the second order constraint equation. A dynamic model and a coupling constraint equation are developed from a Jacobian matrix and the Newton‐Euler formulation. The inertia matrix and the Christoffel tensor are analyzed and decomposed into the part concerning actuated joints and the part concerning passive joints. This decomposition is further extended to the dynamic coupling equation and generates an actuation coupling matrix and a dynamic coupling tensor. Two new dynamic coupling indices are hence identified. One is related to an actuation input and the other is related to centrifugal and Coriolis forces. The former reveals the dynamic coupling between the input and the acceleration of passive joints and gives the actuation effect on the passive joints. The latter reveals the dynamic coupling between the centrifugal and Coriolis forces and the acceleration of passive joints and provides the centrifugal and Coriolis effect on the acceleration of passive joints. The study reveals the coupling characteristics of an underactuated manipulator. This is then demonstrated in a three‐link manipulator and extended to a serial manipulator with passive prismatic joint. © 2003 Wiley Periodicals, Inc.
AgentSalon: Facilitating face‐to‐face knowledge exchange by conversations of personal agents
Authors: Sumi Yasuyuki , Mase Kenji 
Published: March 2003

AbstractThis paper introduces a system called AgentSalon, intended to promote the acquaintance and dialogue of people meeting face to face at a place where people share an interest, a hobby, and a situation, such as a museum, the street, a school, an office, or a conference event. AgentSalon has a large display, which can be shared by multiple users. The personal agents belonging to each user are displayed as character animations, which start the conversation automatically. The personal agent usually operates on the portable guide system called PalmGuide, and provides a personal guide service, while managing the personal interests of the user and the behavior history. When the user connects PalmGuide to AgentSalon by infrared, the personal agent is transferred to AgentSalon together with the personal data. Then the agents start the conversation automatically. The content of the conversation is the interests and the behavior history of the users. The agents exchange views based on experience or make recommendations representing the user. The users listening to the conversation find common topics of interest, as if their minds are connected. Thus, a more valuable conversation should be realized, as if absorbed into the conversation of the agents. In this study, AgentSalon is implemented as a service to the participants of an actual conference. The principles of operation and evaluation are presented. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(4): 21–33, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10117
Automatic heart wall contour extraction from MR images using active contour models: Initial contour setting based on principal component analysis
Authors: Yuasa Mayumi , Watanabe Mutsumi , Nishiura Masahide , Yamaguchi Kojiro , Kondo Takeshi , Anno Hirofumi , Muto Kouichi 
Published: March 2003

AbstractFor the problem of initial value setting, which will become a problem in contour extraction using active contour models, we propose in this paper a scheme for effectively inputting the initial values by facilitating user input with statistical models of the contour shapes of the heart wall. We also describe a scheme for extracting and tracking the left ventricular contour of the heart from the MR images by the edge detection method adapted to low‐contrast images. Moreover, we will show the validity of the proposed scheme by comparison with the manually traced results of physicians. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(4): 72–82, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1202
Signal Processing Architectures for Chemical Sensing Microsystems
Authors: Wilson D. M. , Roppel T. 
Published: March 2003

AbstractThis paper reviews several levels of signal processing and associated architectures for chemical sensing microsystems that use either arrays of optical or of physical sensors. Many chemical sensors, because of their interaction and vulnerability to the environment, have been eliminated from inclusion in sensing systems that require high precision and accuracy. This discussion evaluates parametric vs. nonparametric techniques and linear vs. nonlinear signal processing approaches for addressing chemical classification problems using imperfect sensing technologies. Hardware implementations of signal processing and biologically inspired signal processing are also reviewed. Future research into the development of more accurate chemical classification systems demands the customization of current approaches, so that underlying principles of chemical sensors and associated interfering influences do not overburden the computational space, thereby allowing higher accuracy rates.
CMOS Single Chip Gas Detection Systems — Part I
Authors: Hagleitner C. , Hierlemann A. , Brand O. , Baltes H. 
Published: March 2003

AbstractThe current trend to control indoor air‐quality and to monitor environmental pollution has created a strong demand for miniaturized and inexpensive gas sensors for volatile organic compounds (VOCs). Gas sensor arrays based on industrial CMOS‐processes combined with post‐CMOS micromachining (CMOS MEMS) are a promising approach to low‐cost sensor devices. In this article, the state of research of CMOS‐based gas sensor systems is reviewed, and a platform technology is described, which provides the possibility of monolithically integrating several different transducers on a single chip. A design environment, batch‐fabrication processes, and fast testing procedures were developed to realize an example single‐chip gas detection system. The chip includes the transducers, their biasing circuitry, reference elements, a digital interface, and a temperature sensor. The three polymer‐based transducers and their interface electronics will be detailed in the second part of this article [1].
MEMS in RF Filter Applications: Thin‐film Bulk Acoustic Wave Technology
Authors: Aigner R. 
Published: March 2003

AbstractRF‐MEMS filters will replace conventional filters in mobile communication as they offer better performance at lower cost. Requirements and key performance parameters for filters in next‐generation mobile applications are reviewed in detail. The fundamentals of RF‐MEMS filters — and in particular thin‐film bulk acoustic wave (BAW) filters — are summarized in a comprehensive form. The state‐of‐the‐art in BAW filters and future trends are presented. Supplementary information covers manufacturing and commercialization issues.
Real‐time lock‐in energy loss imaging with a novel high‐speed image processing CCD video camera
Authors: Nishikata Kentarou , Shimazaki Yusuke , Kimura Yoshihide , Takai Yoshizo , Ikuta Takashi , Yumen Hideji 
Published: March 2003

AbstractWe have developed a high‐speed image processing CCD video camera for real‐time energy‐loss imaging using a conventional electron microscope with an energy‐loss imaging facility. As an initial demonstration of real‐time lock‐in energy‐loss imaging, a background‐subtracted energy‐loss image was observed by attaching the high‐speed image processing CCD video camera to an analytical electron microscope equipped with a floating‐type energy‐loss imaging analyser. Copyright © 2003 John Wiley & Sons, Ltd.
Surface modification of PVC endotracheal tubes by oxygen glow discharge to reduce bacterial adhesion
Authors: Balazs D. J. , Triandafillu K. , Chevolot Y. , Aronsson B.‐O. , Harms H. , Descouts P. , Mathieu H. J. 
Published: March 2003

AbstractA d.c. oxygen glow discharge was used to modify medical‐grade poly(vinyl chloride) (PVC) to study how surface chemistry and hydrophilicity influence Pseudomonas aeruginosa adhesion. The effects of plasma exposure time on the resulting surface, including chemical composition, wettability and roughness, were assessed using x‐ray photoelectron spectroscopy, contact angle measurements and atomic force microscopy analysis. A significant alteration in the hydrophilicity of the native PVC surface was observed after oxygen glow discharge treatment. The water contact angle decreased from ∼80° to 8–20°, with a weak dependence of the exposure time used. The change in surface wettability resulted from the incorporation of oxygenated functional groups, including esters, ketones and acids, as indicated by XPS analysis. The amount of oxygen incorporation was shown to be essentially independent of plasma exposure time. However, prolonged plasma exposure resulted in increased surface roughness. Bacterial adhesion efficiency was evaluated for PVC modified by 120 s of plasma exposure, because this exposure time was determined to yield the maximum decrease in contact angle. Oxygen plasma treatment of native PVC was found to yield a 70% reduction in bacterial adhesion for the four strains of Pseudomonas aeruginosa tested. Copyright © 2003 John Wiley & Sons, Ltd.
ToF‐SIMS and XPS surface characterization of novel perfluoropolyether–urethane ionomers from aqueous dispersions
Authors: Canteri R. , Speranza G. , Anderle M. , Turri S. , Radice S. 
Published: March 2003

AbstractIn this work a new class of ionomeric block perfluropolyether (PFPE) polyurethanes are presented; these polymers are obtained in the form of aqueous dispersions due to the presence of hydrophilic sites (ionomeric groups such as acetates or trialkylammonium salts) along the macromolecular chain, offering the chance to combine PFPEs in a variety of possible structures for coating or surface treatments with an environmentally friendly use. X‐ray photoelectron spectroscopy analysis at two different sampling depths, as well as time‐of‐flight secondary ion mass spectrometry analysis modelled by the use of principal component analysis (PCA), were used to investigate the first nanometres of the surface samples. It resulted in a clear surface enrichment in fluorine, and the different extent of the fluorine stratification will be discussed in relation to the ionic character, film‐forming from water and cross‐linking. Copyright © 2003 John Wiley & Sons, Ltd.
Analysis of associations with change in a multivariate outcome variable when baseline is subject to measurement error
Authors: Chambless Lloyd E. , Davis Vicki 
Published: March 2003

AbstractA simple general algorithm is described for correcting for bias caused by measurement error in independent variables in multivariate linear regression. This algorithm, using standard software, is then applied to several approaches to the analysis of change from baseline as a function of baseline value of the outcome measure plus other covariates, any of which might have measurement error. The algorithm may also be used when the independent variables differ by component of the multivariate independent variable. Simulations indicate that under various conditions bias is much reduced, as is mean squared error, and coverage of 95 per cent confidence intervals is good. Copyright © 2003 John Wiley & Sons, Ltd.
An EM‐based semi‐parametric mixture model approach to the regression analysis of competing‐risks data
Authors: Ng S. K. , McLachlan G. J. 
Published: March 2003

AbstractWe consider a mixture model approach to the regression analysis of competing‐risks data. Attention is focused on inference concerning the effects of factors on both the probability of occurrence and the hazard rate conditional on each of the failure types. These two quantities are specified in the mixture model using the logistic model and the proportional hazards model, respectively. We propose a semi‐parametric mixture method to estimate the logistic and regression coefficients jointly, whereby the component‐baseline hazard functions are completely unspecified. Estimation is based on maximum likelihood on the basis of the full likelihood, implemented via an expectation‐conditional maximization (ECM) algorithm. Simulation studies are performed to compare the performance of the proposed semi‐parametric method with a fully parametric mixture approach. The results show that when the component‐baseline hazard is monotonic increasing, the semi‐parametric and fully parametric mixture approaches are comparable for mildly and moderately censored samples. When the component‐baseline hazard is not monotonic increasing, the semi‐parametric method consistently provides less biased estimates than a fully parametric approach and is comparable in efficiency in the estimation of the parameters for all levels of censoring. The methods are illustrated using a real data set of prostate cancer patients treated with different dosages of the drug diethylstilbestrol. Copyright © 2003 John Wiley & Sons, Ltd.