bluuebunny/crossref_metadata_2025_split huggingface dataset:
3D MRA coronary axis determination using a minimum cost path approach
Authors: Wink Onno , Frangi Alejandro F. , Verdonck Bert , Viergever Max A. , Niessen Wiro J. 
Published: October 2002

AbstractA method is introduced to automatically find the coronary axis based on two or more user‐defined points, even in the presence of a severe stenosis. The coronary axis is determined by finding a minimum cost path (MCP) in a feature image in which the tubular‐like structures are enhanced. The results of the proposed method were compared with manually drawn central axes to estimate the accuracy. In 32 3D TFE‐EPI acquisitions of patients and volunteers, 14 right coronary arteries (RCAs), 15 left anterior descending arteries (LADs), and eight left circumflex arteries (LCXs) were manually tracked twice by two operators to determine a reference axis and to assess the inter‐ and intra‐user variability. On average, the maximum distance to the reference axis, based on only two user‐defined points, is less than 1.5 mm; the average distance is around 0.65 mm, which is less than the average in‐plane resolution. The results of the method are comparable to those of the manual operators. Magn Reson Med 47:1169–1175, 2002. © 2002 Wiley‐Liss, Inc.
Automatic control of hyperthermic therapy based on real‐time Fourier analysis of MR temperature maps
Authors: Quesson Bruno , Vimeux Frédéric , Salomir Rares , de Zwart Jacco A. , Moonen Chrit T.W. 
Published: October 2002

AbstractLocal hyperthermia is increasingly being used for therapeutic purposes, such as tumor ablation. Heat conduction and energy absorption in vivo during the hyperthermic procedure are largely unknown, thus making feedback temperature control highly desirable. Here, a general method for temperature control based on Fourier transformation (FT) of the bio‐heat equation is presented, taking into account heat diffusion (D) and energy absorption (α) together with temperature distribution derived from rapid, continuous MR temperature mapping. The main advantages of the new method are: 1) the spatial distribution of heat deposition and conduction over the full region of interest (ROI) is taken into account, and 2) the high speed resulting from the use of fast FT (FFT) of temperature maps allows rapid feedback coupling. Initial tests based on MRI‐guided focused ultrasound (FUS) demonstrated that high‐quality temperature regulation can be obtained even for erroneous values of D and α, so long as their relative error remained in the same range. Performance of the automated control procedure was validated ex vivo and in vivo on rabbit thigh using moderate FUS heating. During the procedure, the standard deviation (SD) of the temperature remained in the range of temperature noise obtained by MRI, indicative of the performance of the regulation algorithm. Magn Reson Med 47:1065–1072, 2002. © 2002 Wiley‐Liss, Inc.
Comparison of quantitative perfusion imaging using arterial spin labeling at 1.5 and 4.0 Tesla
Authors: Wang Jiongjiong , Alsop David C. , Li Lin , Listerud John , Gonzalez‐At Julio B. , Schnall Mitchell D. , Detre John A. 
Published: October 2002

AbstractHigh‐field arterial spin labeling (ASL) perfusion MRI is appealing because it provides not only increased signal‐to‐noise ratio (SNR), but also advantages in terms of labeling due to the increased relaxation time T1 of labeled blood. In the present study, we provide a theoretical framework for the dependence of the ASL signal on the static field strength, followed by experimental validation in which a multislice pulsed ASL (PASL) technique was carried out at 4T and compared with PASL and continuous ASL (CASL) techniques at 1.5T, both in the resting state and during motor activation. The resting‐state data showed an SNR ratio of 2.3:1.4:1 in the gray matter and a contrast‐to‐noise ratio (CNR) of 2.7:1.1:1 between the gray and white matter for the difference perfusion images acquired using 4T PASL, 1.5T CASL, and 1.5T PASL, respectively. However, the functional data acquired using 4T PASL did not show significantly improved sensitivity to motor cortex activation compared with the 1.5T functional data, with reduced fractional perfusion signal change and increased intersubject variability. Possible reasons for these experimental results, including susceptibility effects and physiological noise, are discussed. Magn Reson Med 48:242–254, 2002. © 2002 Wiley‐Liss, Inc.
CDNA microarray analysis of gene expression in fibroblasts of patients with x‐linked Emery–Dreifuss muscular dystrophy
Authors: Tsukahara Toshifumi , Tsujino Seiichi , Arahata Kiichi 
Published: October 2002

AbstractTo clarify the molecular nature of the pathogenesis in X‐linked Emery–Dreifuss muscular dystrophy (EDMD), we monitored the expression of 2400 genes in control and EDMD fibroblasts by using complementary DNA (cDNA) microarray techniques. A total of 60 genes whose expression was altered in EDMD fibroblasts when compared with control fibroblasts were identified. Twenty‐eight genes whose expression was altered with the emerin deficiency were rescued by infection with a recombinant adenovirus expressing emerin. The altered expression in five genes, including the lamin A/C gene, was confirmed by reverse transcription–polymerase chain reaction. Our preliminary results suggest a correlation between disease similarity and gene expression. We conclude that the cDNA microarray is a very efficient tool to clarify genetic and pathological features of diseases. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 898–901, 2002
Impaired performance of skeletal muscle in α‐glucosidase knockout mice
Authors: Hesselink Reinout P. , Gorselink Marchel , Schaart Gert , Wagenmakers Anton J.M. , Kamphoven Joep , Reuser Arnold J.J. , Van der Vusse Ger J. , Drost Maarten R. 
Published: October 2002

AbstractGlycogen storage disease type II (GSD II) is an inherited progressive muscle disease in which lack of functional acid α‐glucosidase (AGLU) results in lysosomal accumulation of glycogen. We report on the impact of a null mutation of the acid α‐glucosidase gene (AGLU−/−) in mice on the force production capabilities, contractile mass, oxidative capacity, energy status, morphology, and desmin content of skeletal muscle. Muscle function was assessed in halothane‐anesthetized animals, using a recently designed murine isometric dynamometer. Maximal torque production during single tetanic contraction was 50% lower in the knockout mice than in wild type. Loss of developed torque was found to be disproportionate to the 20% loss in muscle mass. During a series of supramaximal contraction, fatigue, expressed as percentile decline of developed torque, did not differ between AGLU−/− mice and age‐matched controls. Muscle oxidative capacity, energy status, and protein content (normalized to either dry or wet weight) were not changed in knockout mice compared to control. Alterations in muscle cell morphology were clearly visible. Desmin content was increased, whereas α‐actinin was not. As the decline in muscle mass is insufficient to explain the degree in decline of mechanical performance, we hypothesize that the large clusters of noncontractile material present in the cytoplasm hamper longitudinal force transmission, and hence muscle contractile function. The increase in muscular desmin content is most likely reflecting adaptations to altered intracellular force transmission. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 873–883, 2002
Serial studies of carpal tunnel syndrome during and after pregnancy
Authors: Weimer Louis H. , Yin June , Lovelace Robert E. , Gooch Clifton L. 
Published: October 2002

AbstractCarpal tunnel syndrome (CTS) is a frequent and underdiagnosed complication of pregnancy. Conservative therapies are common initial measures, but data on the course of improvement are limited. We report a case of pregnancy‐associated CTS with unusually detailed serial electrophysiologic studies before and after wrist splinting. Physiologic measures reached a nadir and then rapidly improved following conservative therapy, paralleling clinical improvement. Responses took between 6 and 20 months postpartum to approach baseline values. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
Effects of age and gene dose on skeletal muscle sodium channel gating in mice deficient in myotonic dystrophy protein kinase
Authors: Reddy Sita , Mistry Dilaawar J. , Wang Qing Cai , Geddis Lisa M. , Kutchai Howard C. , Moorman J. Randall , Mounsey J. Paul 
Published: October 2002

AbstractMyotonic muscular dystrophy (DM) is characterized by abnormal skeletal muscle Na channel gating and reduced levels of myotonic dystrophy protein kinase (DMPK). Electrophysiological measurements show that mice deficient in Dmpk have reduced Na currents in muscle. We now find that the Na channel expression level is normal in mouse muscle partially or completely deficient in Dmpk. Reduced current amplitudes are not changed by age or gene dose, and the reduction is not due to changes in macroscopic or microscopic gating kinetics. The mechanism of abnormal membrane excitability in DM may in part be silencing of muscle Na channels due to Dmpk deficiency. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
Reinnervation of muscles after transection of the sciatic nerve in adult rats
Authors: Ijkema‐Paassen Jos , Meek Marcel F. , Gramsbergen Albert 
Published: October 2002

AbstractFunctional recovery after transection of the sciatic nerve in adult rats is poor, probably because of abnormalities in reinnervation. Denervation and reinnervation patterns were studied morphologically in the lateral gastrocnemius (LGC), tibialis anterior (TA), and soleus (SOL) muscles for 21 weeks after nerve transection (motor endplates by acetylcholinesterase staining; nerves by silver impregnation). Motor endplates in the TA showed improving morphology with age, and, at 21 weeks, three‐quarters of these were normal. Poorest recovery was observed in the SOL, as, at 21 weeks, only one‐third of the motor endplates had a normal morphology. Polyneuronal innervation initially was more pronounced in the SOL, but, at 21 weeks, 10% of the motor endplates in all three muscles were still polyneuronally innervated. Our results indicate important differences in the reinnervation of these three hindleg muscles, and, even at 5 months, abnormalities were still present. These factors may in part explain the abnormal locomotion in rats as well as the limited recovery of function observed clinically in humans after nerve transection. © 2002 Wiley Periodicals Inc. Muscle Nerve 25: 000–000, 2002
Three‐dimensional analysis of single pile response to lateral soil movements
Authors: Pan J. L. , Goh A. T. C. , Wong K. S. , Selby A. R. 
Published: October 2002

AbstractThree‐dimensional finite element analysis was carried out to investigate the behaviour of single piles subjected to lateral soil movements and to determine the ultimate soil pressures acting along the pile shaft. The finite element analysis program ABAQUS was used for the analysis and run on a SUN Workstation. The von Mises constitutive model was employed to model the non‐linear stress–strain soil behaviour. The pile was assumed to have linear elastic behaviour. This was considered to be a reasonable approximation, as the maximum stress developed in the pile did not exceed the yield stress of the concrete pile. The length of the pile is 15 m, the width of the square pile is 1 m. The three‐dimensional finite element mesh used in the analysis was optimized taking into account the computing capacity limitations of the Sun Workstation. The computed ultimate soil pressures agreed well with those from the literature. The shapes of the soil pressure versus soil movement curves and the soil pressure versus the relative soil–pile displacement curves as well as the magnitude of the relative soil–pile displacement to mobilize the ultimate soil pressures were in reasonable agreement with those reported by other researchers. Copyright © 2002 John Wiley & Sons, Ltd.
A Generalized Backward Euler algorithm for the numerical integration of an isotropic hardening elastoplastic model for mechanical and chemical degradation of bonded geomaterials
Authors: Tamagnini Claudio , Castellanza Riccardo , Nova Roberto 
Published: October 2002

AbstractAn extended version of the classical Generalized Backward Euler (GBE) algorithm is proposed for the numerical integration of a three‐invariant isotropic‐hardening elastoplastic model for cemented soils or weak rocks undergoing mechanical and non‐mechanical degradation processes. The restriction to isotropy allows to formulate the return mapping algorithm in the space of principal elastic strains. In this way, an efficient and robust integration scheme is developed which can be applied to relatively complex yield surface and plastic potential functions. Moreover, the proposed algorithm can be linearized in closed form, thus allowing for quadratic convergence in the global Newton iteration. A series of numerical experiments are performed to illustrate the accuracy and convergence properties of the algorithm. Selected results from a finite element analysis of a circular footing on a soft rock layer undergoing chemical weathering are then presented to illustrate the algorithm performance at the boundary value problem level. Copyright © 2002 John Wiley & Sons, Ltd.
Fuzzy parameters analysis of time‐dependent fracture of concrete dam models
Authors: Barpi Fabrizio , Valente Silvio 
Published: October 2002

AbstractIn order to apply the mechanical properties (measured on material specimens or laboratory‐sized models) to large structures (such as concrete dams), a non‐linear theory able to predict the size‐scale effect has to be used. One of these theories was first proposed by Hillerborg and co‐workers (fictitious crack model) and is based on the earlier works by Barenblatt and Dugdale for metals (cohesive crack model). It is based on the existence of a fracture process zone (FPZ), where the material undergoes strain softening. The behaviour of the material outside the FPZ is linear elastic.A large number of short‐time laboratory tests were executed, by varying the load, under crack mouth opening displacement control. Since concrete exhibits a time‐dependent behaviour, an interaction between creep and micro‐crack growth occurs in the FPZ. Therefore, different testing conditions can be applied: rupture can be achieved by keeping the load constant before peak value (pre‐peak tests), or after peak value and after an unloading and reloading procedure (post‐peak tests). The crack propagation rate is shown to be small enough to neglect inertial forces and large enough to keep the time‐dependent behaviour of the process zone as dominant compared to the behaviour of the undamaged and viscoelastic zone.Due to the variability in material microstructure from one specimen to another, experimental data show large ranges of scatter. Well established methods in probability theory require sufficient experimental data in order to assume a probability density distribution. The objective of this study is to investigate the ranges of variation of the time response under constant load in simple structural elements associated with pre‐selected variation (fuzziness) in the main material parameters. For situations where the values of the material parameters are of a non‐stochastic nature, the fuzzy set approach to modelling variability has been proposed as a better and more natural approach. Copyright © 2002 John Wiley & Sons, Ltd.
Optimal service rates of a service facility with perishable inventory items
Authors: Berman O. , Sapna K.P. 
Published: October 2002

AbstractIn this paper we optimally control service rates for an inventory system of service facilities with perishable products. We consider a finite capacity system where arrivals are Poisson‐distributed, lifetime of items have exponential distribution, and replenishment is instantaneous. We determine the service rates to be employed at each instant of time so that the long‐run expected cost rate is minimized for fixed maximum inventory level and capacity. The problem is modelled as a semi‐Markov decision problem. We establish the existence of a stationary optimal policy and we solve it by employing linear programming. Several numerical examples which provide insight to the behavior of the system are presented. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 464–482, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10021
On the (S − 1, S) lost sales inventory model with priority demand classes
Authors: Dekker R. , Hill R.M. , Kleijn M.J. , Teunter R.H. 
Published: October 2002

AbstractIn this paper an inventory model with several demand classes, prioritised according to importance, is analysed. We consider a lot‐for‐lot or (S − 1, S) inventory model with lost sales. For each demand class there is a critical stock level at and below which demand from that class is not satisfied from stock on hand. In this way stock is retained to meet demand from higher priority demand classes. A set of such critical levels determines the stocking policy. For Poisson demand and a generally distributed lead time, we derive expressions for the service levels for each demand class and the average total cost per unit time. Efficient solution methods for obtaining optimal policies, with and without service level constraints, are presented. Numerical experiments in which the solution methods are tested demonstrate that significant cost reductions can be achieved by distinguishing between demand classes. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 593–610, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10032
Regulation of neuronal excitability in Drosophila by constitutively active CaMKII
Authors: Park Demian , Coleman Melissa J. , Hodge James J. L. , Budnik Vivian , Griffith Leslie C. 
Published: October 2002

AbstractThe ability of calcium/calmodulin‐dependent protein kinase II (CaMKII) to become calcium independent after autophosphorylation makes this enzyme a temporal marker of neuronal activity. Here we show that the calcium‐independent form of CaMKII has unique effects on larval viability, locomotion, and neuronal excitability in Drosophila. Expression of constitutively active T287D, but not calcium‐dependent T287A, mutant CaMKII in Drosophila neurons resulted in decreased viability, behavioral defects, and failure of action potential propagation. The actions of T287D may be mediated, at least in part, by increased potassium conductances. Expression of T287D CaMKII also stimulated an increase in the number of boutons at the larval neuromuscular junction, but did not affect the mechanics of release. This study defines a role for autophosphorylation of CaMKII in the regulation of multiple neuronal functions including the intrinsic properties of neurons. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 24–42, 2002
Interval static displacement analysis for structures with interval parameters
Authors: Chen Suhuan , Lian Huadong , Yang Xiaowei 
Published: October 2002

AbstractIn this paper, a new method to solve the uncertain static displacement problem of structures with interval parameters is presented. It is difficult to obtain all possible solutions with sharp bounds even if an optimum scheme is adopted when there are many uncertain parameters. With the interval mathematics, the interval finite element equation is developed. Based on the perturbation and the interval extension, the upper and lower bounds of the static displacements are obtained, in which the sharp bounds are guaranteed by the interval calculation operators. Two numerical examples, a box cantilever beam and an automobile frame, are given to illustrate the validity of the present method. Copyright © 2001 John Wiley & Sons, Ltd.
Computational micro‐mechanical model of flexible woven fabric for finite element impact simulation
Authors: Tabiei Ala , Ivanov Ivelin 
Published: October 2002

AbstractThis work presents a computational material model of flexible woven fabric for finite element impact analysis and simulation. The model is implemented in the non‐linear dynamic explicit finite element code LSDYNA. The material model derivation utilizes the micro‐mechanical approach and the homogenization technique usually used in composite material models. The model accounts for reorientation of the yarns and the fabric architecture. The behaviour of the flexible fabric material is achieved by discounting the shear moduli of the material in free state, which allows the simulation of the trellis mechanism before packing the yarns. The material model is implemented into the LSDYNA code as a user defined material subroutine. The developed model and its implementation is validated using an experimental ballistic test on Kevlar woven fabric. The presented validation shows good agreement between the simulation utilizing the present material model and the experiment. Copyright © 2001 John Wiley & Sons, Ltd.
Overlapping Schwarz preconditioners for spectral element discretizations of convection‐diffusion problems
Authors: Pavarino Luca F. 
Published: October 2002

AbstractThe classical overlapping Schwarz algorithm is here extended to stabilized spectral element discretizations of convection‐diffusion problems. The algorithm solves iteratively the resulting non‐symmetric system of linear equations by a preconditioned GMRES method. The preconditioner is built from local convection‐diffusion solvers on overlapping subdomains and from a coarse convection‐diffusion solver on a coarse mesh defined by the subdomain boundaries. Several numerical experiments on test problems in the plane indicate that this algorithm retains the fast convergence rate and optimal scalability properties of classical overlapping methods for diffusion dominated problems. Fast convergence is also obtained for convection dominated problems without closed streamlines and with a moderate number of subdomains. Copyright © 2001 John Wiley & Sons, Ltd.
Non‐weak/strong solutions in gas dynamics: a C11p‐version STLSFEF in Eulerian frame of reference using ρ, u, p primitive variables
Authors: Surana K. S. , Van Dyne David G. 
Published: October 2002

AbstractThis paper presents a space–time least squares finite element formulation of one‐dimensional transient Navier–Stokes equations (governing differential equations: GDE) for compressible flow in Eulerian frame of reference using ρ, u, p as primitive variables with C11 type p‐version hierarchical interpolations in space and time. Time marching procedure is utilized to compute time evolutions for all values of time. For high speed gas dynamics the C11 type interpolations in space and time possess the same orders of continuity in space and time as the GDE. It is demonstrated that with this approach accurate numerical solutions of Navier–Stokes equations are possible without any assumptions or approximations. In the approach presented here SUPG, SUPG/DC, SUPG/DC/LS operators are neither used nor needed. Time accurate numerical simulations show resolution of shock structure (i.e. shock speed, shock relations and shock width) to be in excellent agreement with the analytical solutions. The role of diffusion i.e. viscosity (physical or artificial) and thermal conductivity on shock structure is demonstrated. Riemann shock tube is used as a model problem. True time evolutions are reported beginning with the first time step until steady shock conditions are achieved. In this approach, when the computed error functionals become zero (computationally), the computed non‐weak solutions have characteristics as those of the strong solutions of the gas dynamics equations. Copyright © 2001 John Wiley & Sons, Ltd.