bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maximal voluntary ventilation in myasthenia gravis
Authors: Heliopoulos Ioannis , Patlakas Georgios , Vadikolias Kostantinos , Artemis Nicolaos , Kleopa Kleopas A. , Maltezos Eustratios , Piperidou Haritomeni 
Published: May 2003

AbstractAssessment of respiratory muscle weakness is important at all stages of myasthenia gravis. The maximal voluntary ventilation (MVV) is an objective dynamic method for measuring the working capacity of respiratory muscles. The clinical value of this method was studied in 24 newly diagnosed patients with myasthenia gravis, classified according to Osserman criteria (grades I, IIa, and IIb). The MVV values were normal in group I, whereas a characteristic “myasthenic pattern” of decremental respiratory volumes was demonstrated during MVV in group IIa and IIb patients, with or without dyspnea. Despite some limitations and lack of specificity, MVV may be a valuable tool in the assessment of respiratory dysfunction in patients with myasthenia gravis. Muscle Nerve, 27: 715–719, 2003
Ambulatory foot temperature measurement: A new technique in polyneuropathy evaluation
Authors: Kang Peter B. , Hoffman Stuart N. , Krimitsos Ellen , Rutkove Seward B. 
Published: May 2003

AbstractComplaints of abnormal foot temperature are common among patients with polyneuropathy. However, there is no published method of ambulatory foot temperature measurement to identify possible thermoregulatory disturbances in these patients. We configured a digital electronic thermometer and thermocouple to measure and record distal foot and ambient temperatures simultaneously every minute for 24 to 48 h. Sixteen patients with polyneuropathy and 5 normal subjects were studied; 12 patients with polyneuropathy and 4 normal subjects had at least 24 h of successful recording. The data obtained from these patients were consistent and easily summarized by standard statistical methods. In the others, technical difficulties produced nonphysiological readings. In the patients with polyneuropathy, changes in foot temperature mirrored ambient temperature fluctuations more closely than in normal subjects. This technique shows promise in studying temperature regulation in the feet and may provide new insights into neuropathy‐associated pain and the pathogenesis of polyneuropathy. Muscle Nerve 27: 737–742, 2003
Morphological changes in muscle tissue of patients with infantile Pompe's disease receiving enzyme replacement therapy
Authors: Winkel Léon P. F. , Kamphoven Joep H. J. , Van Den Hout Hannerieke J. M. P. , Severijnen Lies A. , Van Doorn Pieter A. , Reuser Arnold J. J. , Van Der Ploeg Ans T. 
Published: May 2003

AbstractPompe's disease (glycogen storage disease type II) is an autosomal recessive myopathy caused by lysosomal α‐glucosidase deficiency. Enzyme replacement therapy (ERT) is currently under development for this disease. We evaluated the morphological changes in muscle tissue of four children with infantile Pompe's disease who received recombinant human α‐glucosidase from rabbit milk for 72 weeks. The patients were 2.5–8 months of age at entry. Prior to treatment, all patients showed lysosomal glycogen storage in skeletal and smooth muscle cells, vascular endothelium, Schwann cells, and perineurium. The first response to treatment was noticed in vascular endothelium and in peripheral nerves after 12 weeks of treatment at an enzyme dose of 15–20 mg/kg. Increasing the dose to 40 mg/kg led, after 72 weeks of treatment, to a reduction of glycogen storage and substantial improvement of muscle architecture in the least affected patient. Not all patients responded equally well, possibly due to differences in degree of glycogen storage and concomitant muscle pathology at the start of treatment. We conclude that intravenous administration of recombinant human α‐glucosidase from rabbit milk can improve muscle morphology in classic infantile Pompe's disease when treatment is started before irreversible damage has occurred. Muscle Nerve 27: 743–751, 2003
Quantitative ultrasonography of skeletal muscles in children: Normal values
Authors: Scholten R.R. , Pillen S. , Verrips A. , Zwarts M.J. 
Published: May 2003

AbstractThe purpose of this study was to establish normal values of muscle thickness, ratio of muscle thickness to subcutaneous fat thickness, and muscle echo intensity in children between 11 weeks and 16 years of age. Transverse scans of four muscles were made by standardized real‐time ultrasound examination. The scans were digitized, and mean echo intensity was measured using gray‐scale analysis. A multiple regression equation was used to study which independent parameter (age, height, weight, or sex) influenced the variables for each muscle. Muscle thickness depended on the child's weight. The other parameters did not significantly influence muscle thickness after correction for weight. The ratio of muscle thickness to subcutaneous fat thickness depended on age. Echo intensity showed no correlation with either of the variables. As a result, all normal values, including the equation to calculate them, are described. These normal data may help to determine the diagnostic value of muscle ultrasound in children with suspected neuromuscular disease. Muscle Nerve 27: 693–698, 2003
Quantitative skeletal muscle ultrasonography in children with suspected neuromuscular disease
Authors: Pillen S. , Scholten R.R. , Zwarts M.J. , Verrips A. 
Published: May 2003

AbstractWe determined prospectively the diagnostic value of quantitative ultrasonography in detecting neuromuscular disorders in children. Ultrasonographic scans of four muscles were made in 36 children with symptoms or signs suggestive of neuromuscular disease, such as muscle weakness and hypotonia. The muscle thickness, ratio of muscle thickness to subcutaneous fat thickness, and echo intensity were determined in each muscle. The echo intensity was measured using computer‐assisted gray‐scale analysis. Thirteen of the 36 patients had a neuromuscular disorder (6 a myopathy and 7 a neuropathy). Differentiation between neuromuscular diseases and nonneuromuscular diseases could be made on the basis of echo intensities with a sensitivity of 92%, a specificity of 90%, a positive predictive value of 86%, and a negative predictive value of 95%. We conclude that computer‐assisted quantitative analysis of muscle echo intensity is a reliable method to discriminate between neuromuscular and nonneuromuscular diseases in children. Muscle Nerve 27: 699–705, 2003
Motoneuron excitability and the F wave
Authors: Espiritu M. Geraldine , Lin Cindy S.‐Y. , Burke David 
Published: May 2003

AbstractFor three motoneuron pools that differ in excitability to Ia inputs [tibialis anterior (TA), abductor pollicis brevis (APB), and soleus], F‐wave parameters were measured at rest, during voluntary contraction, and following prolonged vibration. There was an inverse relationship between F‐wave chronodispersion and F‐wave persistence at rest, and this appeared to be related to the ease of recording the H reflex for the motoneuron pool. During a steady voluntary contraction, overall F‐wave activity increased in amplitude but decreased in duration for TA and APB. Following vibration of the test muscle at 50 HZ for 10 min there was a long‐lasting depression of the H reflexes of TA and APB, but no significant change in F‐wave measurements. These findings are consistent with the view that reflex discharges can prevent F waves in low‐threshold motor units, and that chronodispersion is affected by the extent of reflex activity; that is, chronodispersion and related F‐wave measurements do not measure motor properties exclusively. The findings also suggest that F waves provide a flawed measure of the excitability of the motoneuron pool. Muscle Nerve 27: 720–727, 2003
Simultaneous backward stability of Gauss and Gauss–Jordan elimination
Authors: Peña J. M. 
Published: May 2003

AbstractIt is well known that some pivoting strategies are backward stable for Gauss elimination but are not backward stable for Gauss–Jordan elimination (GJE) when these procedures are used to solve a linear system Ax=b. We analyse the simultaneous backward stability for Gauss and GJE of several pivoting strategies, including a pivoting strategy which we call double partial pivoting. Copyright © 2002 John Wiley & Sons, Ltd.
Algebraic formulations for the solution of the nullspace‐free eigenvalue problem using the inexact Shift‐and‐Invert Lanczos method
Authors: Simoncini V. 
Published: May 2003

AbstractGiven the generalized symmetric eigenvalue problem Ax=λMx, with A semidefinite and M definite, we analyse some algebraic formulations for the approximation of the smallest non‐zero eigenpairs, assuming that a sparse basis for the null space is available. In particular, we consider the inexact version of the Shift‐and‐Invert Lanczos method, and we show that apparently different algebraic formulations provide the same approximation iterates, under some natural hypotheses. Our results suggest that alternative strategies need to be explored to really take advantage of the special problem setting, other than reformulating the algebraic problem. Experiments on a real application problem corroborate our theoretical findings. Copyright © 2002 John Wiley & Sons, Ltd.
A shell problem ‘highly sensitive’ to thickness changes
Authors: Bathe Klaus‐Jürgen , Chapelle Dominique , Lee Phill‐Seung 
Published: May 2003

AbstractIn general, shell structural problems can be identified to fall into one of the categories of membrane‐dominated, bending‐dominated and mixed shell problems. The asymptotic behaviour with a well‐defined load‐scaling factor shows distinctly into which category a given shell problem falls. The objective of this paper is to present a shell problem and its solution for which there is no convergence to a well‐defined load‐scaling factor as the thickness of the shell decreases. Such shells are unduly sensitive in their behaviour because the ratio of membrane to bending energy stored changes significantly and indeed can fluctuate with changes in shell thickness. We briefly review the different asymptotic behaviours that shell problems can display, and then present the specific problem considered and its numerical solution using finite element analysis. Copyright © 2003 John Wiley & Sons, Ltd.
Exploiting partial or complete geometrical symmetry in 3D symmetric Galerkin indirect BEM formulations
Authors: Bonnet Marc 
Published: May 2003

AbstractProcedures based on group representation theory, allowing the exploitation of geometrical symmetry in symmetric Galerkin BEM formulations, are investigated. In particular, this investigation is based on the weaker assumption of partial geometrical symmetry, where the boundary has two disconnected components, one of which is symmetric; e.g. this can be very useful for defect identification problems. The main development is expounded in the context of 3D Neumann elastostatic problems, considered as model problems; and then extended to SGBIE formulations for Dirichlet and/or scalar problems. Both Abelian and non‐Abelian finite symmetry groups are considered. The effectiveness of the present approach is demonstrated through numerical examples, where both partial and complete symmetry are considered, in connection with both Abelian and non‐Abelian symmetry groups. Copyright © 2003 John Wiley & Sons, Ltd.
Mechanically based models: Adaptive refinement for B‐spline finite element
Authors: Kagan Pavel , Fischer Anath , Bar‐Yoseph Pinhas Z. 
Published: May 2003

AbstractThis article presents two new methods for adaptive refinement of a B‐spline finite element solution within an integrated mechanically based computer aided engineering system. The proposed techniques for adaptively refining a B‐spline finite element solution are a local variant of np‐refinement and a local variant of h‐refinement. The key component in the np‐refinement is the linear co‐ordinate transformation introduced into the refined element. The transformation is constructed in such a way that the transformed nodal configuration of the refined element is identical to the nodal configuration of the neighbour elements. Therefore, the assembly proceeds as with classic finite elements, while the solution approximation conforms exactly along the inter‐element boundaries. For the h‐refinement, this transformation is introduced into a construction that merges the super element from the finite element world with the hierarchical B‐spline representation from the computational geometry. In the scope of developing sculptured surfaces, the proposed approach supports C0 as well as the Hermite B‐spline C1 continuous shapes. For sculptured solids, C0 continuity only is considered in this article. The feasibility of the proposed methods in the scope of the geometric design is demonstrated by several examples of creating sculptured surfaces and volumetric solids. Numerical performance of the methods is demonstrated for a test case of the two‐dimensional Poisson equation. Copyright © 2003 John Wiley & Sons, Ltd.
On a consistent hourglass stabilization technique to treat large inelastic deformations and thermo‐mechanical coupling in plane strain problems
Authors: Reese Stefanie 
Published: May 2003

AbstractIn linear elasticity, the concept of reduced integration combined with hourglass stabilization can be directly derived from a mixed method, if certain assumptions are made. Such a derivation is much more difficult when the relation between stress and strain is highly non‐linear. Earlier works use the linearized form of a classical multi‐field functional in order to derive the hourglass stabilization analytically. In the present contribution, it is shown how such stabilization techniques can be directly derived at the level of the weak form. Crucial to the new concept is a Taylor expansion of the constitutively dependent quantities with respect to the centre of the element. The approach is suitable for various kinds of inelastic material models and thermo‐mechanical coupling. One of the important features of the new element technology is its computational efficiency which is especially visible when the numerical effort at the element level is very high. Copyright © 2003 John Wiley & Sons, Ltd.
Algebraic elimination of slide surface constraints in implicit structural analysis
Authors: Chow Edmond , Manteuffel Thomas A. , Tong Charles , Wallin Bradley K. 
Published: May 2003

AbstractSlide surface and contact boundary conditions can be implemented via Lagrange multipliers in the algebraic equations in implicit structural analysis. This indefinite set of equations is difficult to solve by iterative methods and is often too large to be solved by direct methods. When there are m constraints and there exists a set of m variables where each variable is only involved in a single constraint, we advocate a direct elimination technique which leaves a sparse, positive definite system to solve by iterative methods. We prove that the amount of ‘fill‐in’ created by this process is independent of the size of the slide surfaces. In addition, the eigenvalues of the reduced matrix do not differ significantly from the eigenvalues of the unconstrained matrix. This method can be extended to the case where constrained surfaces intersect and leads to a graph theoretic approach for determining which variables can be eliminated efficiently for constraints with more general structure. Published in 2003 by John Wiley & Sons, Ltd.
Some observations on unsymmetric radial basis function collocation methods for convection–diffusion problems
Authors: Li Jichun , Chen C. S. 
Published: May 2003

AbstractIn this paper, we re‐investigate the unsymmetric radial basis function (RBF) collocation method for solving convection–diffusion problems with high Péclet number as in Power and Barraco (Computers and Mathematics with Applications 2002; 43:551). By testing different RBFs and different numbers of nodes, we found that the unsymmetric method can still solve high Péclet number problems reasonably well by using more nodes and domain decomposition techniques. Compared to solving one large problem, the domain decomposition method is shown to be very efficient and can improve the accuracy especially when the Péclet number is not that high. From our tests, it seems that the RBFs r4 ln r and r8 ln r are not very stable, while r6 ln r, r5 and r7 perform very well. Copyright © 2003 John Wiley & Sons, Ltd.
Topology optimization with implicit functions and regularization
Authors: Belytschko T. , Xiao S. P. , Parimi C. 
Published: May 2003

AbstractTopology optimization is formulated in terms of the nodal variables that control an implicit function description of the shape. The implicit function is constrained by upper and lower bounds, so that only a band of nodal variables needs to be considered in each step of the optimization. The weak form of the equilibrium equation is expressed as a Heaviside function of the implicit function; the Heaviside function is regularized to permit the evaluation of sensitivities. We show that the method is a dual of the Bends–Kikuchi method. The method is applied both to problems of optimizing single material and multi‐material configurations; the latter is made possible by enrichment functions based on the extended finite element method that enable discontinuous derivatives to be accurately treated within an element. The method is remarkably robust and we found no instances of checkerboarding. The method handles topological merging and separation without any apparent difficulties. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis and characterization of conducting copolymers from aniline and o‐anisidine in HCl solutions
Authors: Rehan HH , Al‐Mazroa SH , Al‐Fawzan FF 
Published: May 2003

AbstractConducting poly(aniline‐co‐o‐anisidine) (PAS) films with different ratios of aniline units in the polymer chain were prepared by oxidative polymerization of different molar ratios of aniline and o‐anisidine in 1 M HCl using cyclic voltammetry. Due to the much higher reactivity of o‐anisidine, the structure and properties of PASs were found to be dominated by the o‐anisidine units. The polymerization of poly‐o‐anisidine and PASs followed zero‐order kinetics with respect to formation of the polymer (film thickness) and the autocatalytic polymerization of aniline was completely inhibited. In contrast to polyaniline, a decrease in the polymerization temperature was found to increase the amount of copolymer formed and its redox charge. The presence of aniline units in PASs led to a pronounced increase in the molecular weight and conductivity, and a decrease in the solubility in organic solvents. Repetitive charging/discharging cycles showed that PASs resist degradation more than polyaniline. Copyright © 2003 Society of Chemical Industry
Study of the effect of BDMA catalyst in the epoxy novolac curing process by isothermal DSC
Authors: Firouzmanesh MR , Azar A Aref 
Published: May 2003

AbstractEpoxy novolac/anhydride cure kinetics has been studied by differential scanning calorimetry under isothermal conditions. The system used in this study was an epoxy novolac resin (DEN431), with nadic methyl anhydride as hardener and benzyldimethylamine as accelerator. Kinetic parameters including the reaction order, activation energy and kinetic rate constants, were investigated. The cure reaction was described with the catalyst concentration, and a normalized kinetic model developed for it. It is shown that the cure reaction is dependent on the cure temperature and catalyst concentration, and that it proceeds through an autocatalytic kinetic mechanism. The curing kinetic constants and the cure activation energies were obtained using the Arrhenius kinetic model. A suggested kinetic model with a diffusion term was successfully used to describe and predict the cure kinetics of epoxy novolac resin compositions as a function of the catalyst content and temperature. Copyright © 2003 Society of Chemical Industry
Effect of solvent exposure on the properties of hydroxy‐terminated polybutadiene‐based polyurethanes
Authors: Gupta Tarakranjan , De Debasish , Adhikari Basudam 
Published: May 2003

AbstractHydroxy‐terminated polybutadiene‐based prepolyurethanes and diamine chain extended polyurethane‐ureas were prepared and treated with various organic solvents in the moisture‐cured state in order to modify their ultimate strength. FTIR studies with solvent‐treated polyurethanes and polyurethane‐ureas confirmed that organic solvents penetrated inside the polyurethane hard segments and affected hydrogen bonding. The polar and non‐polar solvents showed different abilities to penetrate into polyurethane hard segments. Solvent treatment after moisture curing increased the tensile strength of these polyurethanes and polyurethane‐ureas with respect to control samples. The stress–strain behaviour of solvent‐treated polyurethane follows the constrained junction model. The change in hard segment crystallinity on solvent treatment has been explained by wide‐angle X‐ray diffraction study. The better orientation in polybutadiene soft segments evidenced from SEM (scanning electron microscopy) pictures is believed to be the main reason behind the improved tensile properties of solvent‐treated polyurethane samples. The effect of solvent treatment, as well as stretching, on the diffusion coefficient of hexane in polyurethanes was investigated. Copyright © 2003 Society of Chemical Industry
Analysis of the swelling dynamics of crosslinked P(N‐iPAAm‐co‐MAA) copolymers, the corresponding homopolymers and their interpenetrating networks. Kinetics of water penetration into the gel above the pKaof MAA comonomeric units
Authors: Díez‐Peña E , Quijada‐Garrido I , Frutos P , Barrales‐Rienda JM 
Published: May 2003

AbstractThe effect of composition on the swelling kinetics of a series of crosslinked poly(N‐isopropylacrylamide)s [P(N‐iPAAm)] and poly(methacrylic acid)s [P(MAA)], their statistical copolymers P(N‐iPAAm‐co‐MAA), and some sequential interpenetrating networks (IPNs) has been studied at pHs above the pKa of MAA comonomeric units. The swelling process of the hydrogels upon immersion in buffer solutions was monitored by the weight change as a function of time. First‐order kinetics apply better than second‐order kinetics which fail, especially for predicting swelling equilibrium values. However, hydrogels presenting hydrogen bonding between MAA and N‐iPAAm units do not obey either first‐order or second‐order kinetics. The high n values found indicate that the swelling process is mostly controlled by polymer relaxation. Copyright © 2003 Society of Chemical Industry
Kinetic model of mechanism of alternating radical copolymerization and its quantitative treatment method
Authors: Liu Guo‐Dong , Zhang Yan , Qu Xiong‐Wei , Zhang Liu‐Cheng 
Published: May 2003

AbstractA general mechanism is proposed in this paper with the assumption of homopolymerization, cross‐propagation and kinetically‐controlled termination and a quantitative treatment method is developed. The model proposed is different from that of Shirota and Shan. The kinetic models concerning the participation of charge‐transfer complexed (CTC) monomer and homopolymerization or otherwise, and kinetic‐ or diffusion‐controlled termination are generalized into one equation. The quantitative treatment method proposed can give monomer reactivity ratios without concerning the specific kinetic model. Meanwhile, information on the termination process can also be acquired from the quantitative treatment method. Copyright © 2003 Society of Chemical Industry