bluuebunny/crossref_metadata_2025 huggingface dataset:
A surface‐based integral‐equation formulation for coupled electromagnetic and circuit simulation
Authors: Jandhyala Vikram , Wang Yong , Gope Dipanjan , Richard C. J. , Shi
Published: October 2002

A surface‐based integral‐equation formulation for coupled electromagnetic and circuit simulation is presented. The approach is sufficiently general to model arbitrarily shaped structures and high‐frequency skin effects. The formulation is implemented in both an equivalent circuit form for spice compatibility, and in a more general form as a coupled‐matrix system outside spice. The overall approach can be interpreted as either a modified surface‐only partial element equivalent circuit approach, or as a circuit‐coupled version of the surface‐based method of moments. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 103–106, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10386
Air‐gap type TFBAR‐based filter topologies
Authors: Kim Kun‐Wook , Kim Gwang‐Yong , Yook Jong‐Gwan , Park Han‐Kyu
Published: October 2002

Extremely small bandpass filters with TFBARs using aluminum nitride piezoelectric material have been realized in this study. Resonator modeling has been performed based on the modified Butterworth–Van Dyke (MBVD) model from the measured frequency responses of a single resonator. The predicted filter responses are compared with measured frequency data. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 386–387, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10470
Complete assignment of the NMR spectra of [D‐Leu1]‐microcystin‐LR and analysis of its solution structure
Authors: Schripsema Jan , Dagnino Denise
Published: October 2002

[D‐Leu1]‐microcystin‐LR is a recently discovered microcystin. We report the isolation of this microcystin analogue from a Microcystis aeruginosa strain isolated from the Lagoa de Iquipari, Rio de Janeiro, Brazil. The 1H and 13C NMR spectra were completely assigned in both MeOH‐d4 and DMSO‐d6. Further, the solution structure of this compound was investigated with the use of two‐dimensional NMR and the amide proton temperature dependence, and was compared with those of its analogs, microcystin‐RR and microcystin‐LR. Copyright © 2002 John Wiley & Sons, Ltd.
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

A 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

Local 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

High‐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

To 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

Glycogen 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

Carpal 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

Myotonic 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

Functional 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

Three‐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

An 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

In 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

In 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

In 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

The 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

In 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

This 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

The 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

This 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.
Analytical integrations in 2D BEM elasticity
Authors: Salvadori Alberto
Published: October 2002

In the context of two‐dimensional linear elasticity, this paper presents the closed form of the integrals that arise from both the standard (collocation) boundary element method and the symmetric Galerkin boundary element method. Adopting polynomial shape functions of arbitrary degree on straight elements, finite part of Hadamard, Cauchy principal values and Lebesgue integrals are computed analytically, working in a local coordinate system. For the symmetric Galerkin boundary element method, a study on the singularity of the external integral is conducted and the outer weakly singular integral is analytically performed. Numerical tests are presented as a validation of the obtained results. Copyright © 2001 John Wiley & Sons, Ltd.
Arbitrary Lagrangian–Eulerian (ALE) formulation for hyperelastoplasticity
Authors: Rodríguez‐Ferran Antonio , Pérez‐Foguet Agustí , Huerta Antonio
Published: October 2002

The arbitrary Lagrangian–Eulerian (ALE) description in non‐linear solid mechanics is nowadays standard for hypoelastic–plastic models. An extension to hyperelastic–plastic models is presented here. A fractional‐step method—a common choice in ALE analysis—is employed for time‐marching: every time‐step is split into a Lagrangian phase, which accounts for material effects, and a convection phase, where the relative motion between the material and the finite element mesh is considered. In contrast to previous ALE formulations of hyperelasticity or hyperelastoplasticity, the deformed configuration at the beginning of the time‐step, not the initial undeformed configuration, is chosen as the reference configuration. As a consequence, convecting variables are required in the description of the elastic response. This is not the case in previous formulations, where only the plastic response contains convection terms. In exchange for the extra convective terms, however, the proposed ALE approach has a major advantage: only the quality of the mesh in the spatial domain must be ensured by the ALE remeshing strategy; in previous formulations, it is also necessary to keep the distortion of the mesh in the material domain under control. Thus, the full potential of the ALE description as an adaptive technique can be exploited here. These aspects are illustrated in detail by means of three numerical examples: a necking test, a coining test and a powder compaction test. Copyright © 2001 John Wiley & Sons, Ltd.
A simple algorithm for localized construction of non‐matching structural interfaces
Authors: Park K. C. , Felippa C. A. , Rebel G.
Published: October 2002

A simple and effective algorithm for the modular construction of non‐matched interfaces is presented for the partitioned solution of large‐scale structural problems. The formulation is based on a recently developed four‐field variational principle, which introduces a connection frame between the interfaced partitions. A key result of the present study is a frame nodal placement criterion that uniquely determines the frame discretization into piecewise linear elements so that the interface patch test condition is satisfied a priori. The method is demonstrated with several 2D and 3D example problems. Copyright © 2002 John Wiley & Sons, Ltd.
An hp‐adaptive finite element method for electromagnetics—part II: A 3D implementation
Authors: Rachowicz W. , Demkowicz L.
Published: October 2002

This is the second of papers describing implementations of the hp‐adaptive, mixed finite element (FE) method for the solution of steady‐state Maxwell's equations proposed in Demkowicz and Vardapetyan (Comput. Methods Appl. Mech. Engng. 1998; 152(1–2):103–124). The paper presents a three‐dimensional version of the method based on hexahedral elements of possibly variable order. The elements can be subsected (isotropically or anisotropically), and their orders can be enriched, which allows for non‐uniform distribution of element sizes h and orders p—the hp adaptation. A few numerical examples illustrate the capability of the method. Copyright © 2001 John Wiley & Sons, Ltd.
A 3D brick element based on Hu–Washizu variational principle for mesh distortion
Authors: Cao Yan Ping , Hu Ning , Lu Jian , Fukunaga Hisao , Yao Zhen Han
Published: October 2002

In order to improve the accuracy of the mixed element for irregular meshes, a penalty‐equilibrating 3D‐mixed element based on the Hu–Washizu variational principle has been proposed in this paper. The key idea in this work is to introduce a penalty term into the Hu–Washizu three‐field functional, which can enforce the stress components to satisfy the equilibrium equations in a weak form. Compared with the classical hybrid and mixed elements, this technique can efficiently reduce the sensitivity of the element to mesh distortion. The reason for the better results of this penalty technique has been investigated by considering a simple 2D problem. From this investigation, it has been found that the penalty parameter here plays the role of a scaling factor to reduce the influence of the parasitic strain or stress, which is similar to the devised selective scaling factor proposed by Sze. Furthermore, compared with the hybrid stress element, the proposed element based on the three‐field variational principle is more suitable for material non‐linear analysis. Numerical examples have demonstrated the improved performance of the present element, especially in stress computation when FEM meshes are irregular. Copyright © 2002 John Wiley & Sons, Ltd.
Classical and advanced multilayered plate elements based upon PVD and RMVT. Part 2: Numerical implementations
Authors: Carrera Erasmo , Demasi Luciano
Published: October 2002

This paper presents numerical evaluations related to the multilayered plate elements which were proposed in the companion paper (Part 1). Two‐dimensional modellings with linear and higher‐order (up to fourth order) expansion in the z‐plate/layer thickness direction have been implemented for both displacements and transverse stresses. Layer‐wise as well as equivalent single‐layer modellings are considered on both frameworks of the principle of virtual displacements and Reissner mixed variational theorem. Such a variety has led to the implementation of 22 plate theories. As far as finite element approximation is concerned, three quadrilaters have been considered (four‐, eight‐ and nine‐noded plate elements). As a result, 22×3 different finite plate elements have been compared in the present analysis. The automatic procedure described in Part 1, which made extensive use of indicial notations, has herein been referred to in the considered computer implementations. An assessment has been made as far as convergence rates, numerical integrations and comparison to correspondent closed‐form solutions are concerned. Extensive comparison to early and recently available results has been made for sample problems related to laminated and sandwich structures. Classical formulations, full mixed, hybrid, as well as three‐dimensional solutions have been considered in such a comparison. Numerical substantiation of the importance of the fulfilment of zig‐zag effects and interlaminar equilibria is given. The superiority of RMVT formulated finite elements over those related to PVD has been concluded.

Two test cases are proposed as ‘desk‐beds’ to establish the accuracy of the several theories. Results related to all the developed theories are presented for the first test case. The second test case, which is related to sandwich plates, restricts the comparison to the most significant implemented finite elements. It is proposed to refer to these test cases to establish the accuracy of existing or new higher‐order, refined or improved finite elements for multilayered plate analyses. Copyright © 2002 John Wiley & Sons, Ltd.
Arbitrary order edge elements for electromagnetic scattering simulations using hybrid meshes and a PML
Authors: Ledger P. D. , Morgan K. , Hassan O. , Weatherill N. P.
Published: October 2002

The use of arbitrary order edge elements for the simulation of two‐dimensional electromagnetic scattering problems on hybrid meshes of triangles and quadrilaterals is described. Single‐frequency incident waves, generated by a source in the far field, are considered and the solution is determined in the frequency domain. For numerical simulation, the solution domain is truncated at a finite distance from the perfectly conducting scatterer and the non‐reflecting boundary condition at the truncated boundary is imposed by the use of a perfectly matched layer (PML). Several examples are included to demonstrate the performance of the proposed procedure. Copyright © 2002 John Wiley & Sons, Ltd.
The probability approach to numerical solution of nonlinear parabolic equations
Authors: Milstein G. N.
Published: October 2002

A number of new layer methods for solving semilinear parabolic equations and reaction‐diffusion systems is derived by using probabilistic representations of their solutions. These methods exploit the ideas of weak sense numerical integration of stochastic differential equations. In spite of the probabilistic nature these methods are nevertheless deterministic. A convergence theorem is proved. Some numerical tests are presented. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 490–522, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/num.10020
Cancer as an epigenetic disease: DNA methylation and chromatin alterations in human tumours
Authors: Esteller Manel , Herman James G.
Published: October 2002

Cancer is an epigenetic disease at the same level that it can be considered a genetic disease. In fact, epigenetic changes, particularly DNA methylation, are susceptible to change and are excellent candidates to explain how certain environmental factors may increase the risk of cancer. The delicate organization of methylation and chromatin states that regulates the normal cellular homeostasis of gene expression patterns becomes unrecognizable in the cancer cell. The genome of the transformed cell undergoes simultaneously a global genomic hypomethylation and a dense hypermethylation of the CpG islands associated with gene regulatory regions. These dramatic changes may lead to chromosomal instability, activation of endogenous parasitic sequences, loss of imprinting, illegitimate expression, aneuploidy, and mutations, and may contribute to the transcriptional silencing of tumour suppressor genes. The hypermethylation‐associated inactivation affects virtually all of the pathways in the cellular network, such as DNA repair (hMLH1, BRCA1, MGMT, …︁), the cell cycle (p16INK4a, p14ARF, p15INK4b, …︁), and apoptosis (DAPK, APAF‐1, …︁). The aberrant CpG island methylation can also be used as a biomarker of malignant cells and as a predictor of their behaviour, and may constitute a good target for future therapies. Copyright © 2002 John Wiley & Sons, Ltd.
Overexpression of peroxiredoxins I, II, III, V, and VI in malignant mesothelioma
Authors: Kinnula V. L. , Lehtonen S. , Sormunen R. , Kaarteenaho‐Wiik R. , Kang S. W. , Rhee S. G. , Soini Y.
Published: October 2002

Peroxiredoxins (Prxs) are a recently characterized group of thiol‐containing proteins with efficient antioxidant capacity, capable of consuming hydrogen peroxide in living cells. Altogether six distinct Prxs have been characterized in mammalian tissues. Their expression was investigated in histological samples of mesothelioma and in cell lines established from the tumours of mesothelioma patients. Four cases with histopathologically healthy pleura from non‐smokers were used as controls. Healthy pleural mesothelium was negative or very weakly positive for all Prxs. In mesothelioma, the most prominent reactivity was observed with Prxs I, II, V, and VI. Prx I was highly or moderately expressed in 25/36 cases, the corresponding figures for Prxs II–VI being 27/36 (Prx II), 13/36 (Prx III), 2/36 (Prx IV), 24/36 (Prx V), and 30/36 (Prx VI). Positive staining was observed both in the cytosolic and the nuclear compartment, with the exception of Prx III, which showed no nuclear reactivity. The staining pattern of Prxs III and V was granular. Immunoelectron microscopic localization of Prxs was in accordance with the immunohistochemical findings, showing diffuse cytoplasmic localization for Prxs I, II, IV, and VI and distinct mitochondrial labelling for Prxs III and V. There was no significant association between the extent of staining and different Prxs. It appeared that Prxs may not have prognostic significance, but being prominently expressed in most mesotheliomas these proteins, at least in theory, may play a role in the primary drug resistance of this disease. Copyright © 2002 John Wiley & Sons, Ltd.
Current understanding of cellular and molecular events in intervertebral disc degeneration: implications for therapy
Authors: Freemont A. J. , Watkins A. , Le Maitre C. , Jeziorska M. , Hoyland J. A.
Published: October 2002

Until recently, material removed from the intervertebral disc (IVD) at surgery consisted either of ‘loose bodies’ from the centre of the IVD or discal tissue displaced (prolapsed) into the intervertebral root or spinal canals. This material is best regarded as a by‐product of disc degeneration and therefore not representative of the disease process itself. Recent advances in surgical techniques, particularly anterior fusion, in which large segments of the anterior part of the IVD are excised with the anatomical relationships between different components intact, have generated material that can be investigated with modern molecular and cell biological techniques. This is an important area of study because degeneration of the lumbar IVDs is associated, perhaps causally, with low back pain, one of the most common and debilitating conditions in the West. ‘Degeneration’ carries implications of inevitable progression of wear‐and‐tear associated conditions. Modern research on human IVD tissue has shown that this is far from the case and that disruption of the micro‐anatomy described as degeneration is an active process, regulated by locally produced molecules. The exciting consequence of this observation is the possibility of being able to inhibit or even reverse the processes of degeneration using targeted therapy. Copyright © 2002 John Wiley & Sons, Ltd.
Analysis of key cell‐cycle checkpoint proteins in colorectal tumours
Authors: McKay Judith A. , Douglas Joy J. , Ross Val G. , Curran Stephanie , Loane Joseph F. , Ahmed Fareeda Y. , Cassidy Jim , McLeod Howard L. , Murray Graeme I.
Published: October 2002

Aberrations in the components of cell‐cycle checkpoints are a common feature of many tumours and several have been shown to have prognostic significance in colorectal cancer. In this study, seven components of cell‐cycle control [cyclin D1, retinoblastoma (pRb), p21, p27, p16, p53, and proliferating cell nuclear antigen (PCNA)] were examined in a large series of well‐characterized colorectal adenocarcinomas using immunohistochemistry to ascertain co‐regulation and influence on survival. The majority (92%) of the tumours had abnormal staining of ⩾2 cell‐cycle control factors. Expression of cyclin D1 protein was correlated with both p21 (p<0.001) and p27 (p=0.033), suggesting co‐regulation of these proteins in colorectal tumours. Only cyclin D1 (p=0.048) and p53 (p=0.025) were directly associated with PCNA levels, suggesting a more important role in the proliferative capacity of tumour cells. Significant associations between cell cycle‐related proteins and clinicopathological data were observed: cyclin D1 and p53 proteins were correlated with patient age (p=0.042 and p<0.001, respectively) and p53 (p=0.01) and p21 (p=0.024) proteins were associated with tumour site. Expression of cyclin D1 protein was the only protein examined that was related to improved outcome in these patients (p=0.0266), but itwas not an independent predictor of survival. These results suggest that loss of control of cell‐cycle checkpoints is a common occurrence in colorectal tumours and may be an important therapeutic target. Copyright © 2002 John Wiley & Sons, Ltd.
The Wnt pathway, epithelial–stromal interactions, and malignant progression in phyllodes tumours
Authors: Sawyer Elinor J. , Hanby Andrew M. , Rowan Andrew J. , Gillett Cheryl E. , Thomas Rachel E. , Poulsom Richard , Lakhani Sunil R. , Ellis Ian O. , Ellis Paul , Tomlinson Ian P. M.
Published: October 2002

In a previous study of phyllodes tumours, it has been shown that both the stroma and the epithelium can exhibit distinct molecular changes, suggesting that both are part of the neoplastic process. In view of this finding, it was decided to study stromal–epithelial interactions in these tumours by examining the Wnt–APC–β‐catenin pathway. β‐catenin and cyclin D1 immunohistochemistry was performed on 119 phyllodes tumours. Eighty‐six (72%) showed stromal nuclear β‐catenin localization and in 57% the staining was moderate or strong; however, of the eight malignant tumours in the series, seven showed absent or weak nuclear staining (p<0.025). In no tumour was nuclear β‐catenin staining seen in the epithelial component. Moderate or strong stromal cyclin D1 staining correlated with nuclear stromal β‐catenin staining (p<0.05). Forty‐five of the tumours, including two malignant lesions, were screened for β‐catenin exon 3 mutations using SSCP and sequencing, but none was found. Loss of heterozygosity (LOH) of the marker D5S346 was used to infer APC mutation, but only one (benign) tumour showed LOH. Wnt2 and Wnt5a mRNA was localized by in situ hybridization in 13 cases (three malignant) chosen to reflect the different β‐catenin staining patterns. There was an association between strong nuclear β‐catenin staining of stromal cells and epithelial Wnt5a expression (p<0.0015). These data suggest that stromal proliferation in benign phyllodes tumours relies on abnormalities in the Wnt pathway which result not from mutation, but from Wnt5a expression in the epithelium. In the progression to malignancy, the stromal proliferation appears to become independent of the Wnt pathway and, presumably, of the epithelial component of these tumours. Copyright © 2002 John Wiley & Sons, Ltd.
Malignancy‐associated allelic losses on the X‐chromosome in foregut but not in midgut endocrine tumours
Authors: Pizzi Silvia , D'Adda Tiziana , Azzoni Cinzia , Rindi Guido , Grigolato Piergiovanni , Pasquali Claudio , Corleto Vito D. , Delle Fave Gianfranco , Bordi Cesare
Published: October 2002

Information on genetic changes involved in the progression of gastroenteropancreatic (GEP) endocrine tumours is scanty. On the other hand, the identification of molecular markers of malignancy could be crucial for the prognostic evaluation of these neoplasms, which is hardly predictable on the basis of conventional histological criteria. An association of X‐chromosome deletions with malignancy has already been found in gastric endocrine tumours. To investigate this further, a comparative loss of heterozygosity (LOH) analysis was performed on 17 pancreatic endocrine tumours (PETs) and 17 intestinal (ten ileal, six appendiceal, and one rectal) carcinoids from female patients. The relationship of X‐chromosome LOH with the ploidy status of the neoplasms was also investigated. LOH was found in six of eight malignant PETs (60% of the informative markers), but was infrequent in the nine benign ones (4.5%). In contrast, although retention of heterozygosity was consistently observed in benign midgut tumours, LOH was infrequent in malignant carcinoids (15%). No correlation was found between LOH and the ploidy status. These results indicate an association between X‐chromosome LOH and malignancy in foregut endocrine tumours. The lack of such an association in midgut carcinoids suggests that different molecular mechanisms are involved in the progression of these two categories of endocrine neoplasms, which are otherwise considered to be closely related. These findings emphasize the need for further molecular studies on GEP endocrine tumours, carefully subdivided according to their anatomical site of origin. Copyright © 2002 John Wiley & Sons, Ltd.
Evaluation of seven oestrogen receptor β antibodies for immunohistochemistry, western blotting, and flow cytometry in human breast tissue
Authors: Skliris G. P. , Parkes A. T. , Limer J. L. , Burdall S. E. , Carder P. J. , Speirs V.
Published: October 2002

Two oestrogen receptors, ERα and ERβ, exist. While much is known about ERα, the role of ERβ is still undefined, especially at the protein level. The aim of this study was to determine the utility of seven ERβ antibodies (14C8, 8D5, PAI313, PPG5/10, N19, 9.88, and D7N) raised against different domains of ERβ in three commonly used laboratory applications, namely immunohistochemistry, western blot, and flow cytometry, using human breast material. For immunohistochemical analysis of frozen material, PAI313 and D7N gave stronger and more specific signals than 14C8, 8D5, and PPG5/10. In paraffin sections, 14C8, closely followed by PPG5/10, gave by far the most superior nuclear immunoreactivity, compared with the other antibodies tested. In general, flow cytometry results mirrored the immunohistochemistry data for paraffin sections, with antibodies ranked 14C8>8D5≥PAI‐313>PPG5/10>D7N. For western blotting, 8D5 and D7N yielded the strongest and most consistent bands, with weaker bands seen with the others. It is concluded that ERβ protein can be detected using specific antibodies. However, there is considerable variation between the specificity and application of these antibodies, highlighting the fact that careful optimization is required when selecting an antibody for use in a particular laboratory technique. Copyright © 2002 John Wiley & Sons, Ltd.