bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of networks and protocols in the adversarial queueing model for packet routing
Authors: Goel Ashish
Published: August 2002

The adversarial queueing theory model for packet routing was suggested by Borodin et al. We give a complete and simple characterization of all networks that are universally stable in this model. We show that the same characterization also holds for networks which are stable given that the packet forwarding protocol is FIFO (First in First out). We also show that a specific greedy protocol, SIS (Shortest in System), is stable against 0/1 stochastic adversaries. © 2001 John Wiley & Sons, Inc.
On the construction of combinedk‐fault‐tolerant Hamiltonian graphs
Authors: Hung Chun‐Nan , Hsu Lih‐Hsing , Sung Ting‐Yi
Published: August 2002

A graphGis a combinedk‐fault‐tolerant Hamiltonian graph (also called a combinedk‐Hamiltonian graph) ifG−Fis Hamiltonian for every subsetF⊂ (V(G) ∪E(G)) with |F| =k. A combinedk‐Hamiltonian graphGwith |V(G)| =nis optimal if it has the minimum number of edges among alln‐nodek‐Hamiltonian graphs. Using the concept of node expansion, we present a powerful construction scheme to construct a larger combinedk‐Hamiltonian graph from a given smaller graph. Many previous graphs can be constructed by the concept of node expansion. We also show that our construction maintains the optimality property in most cases. The classes of optimal combinedk‐Hamiltonian graphs that we constructed are shown to have a very good diameter. In particular, those optimal combined 1‐Hamiltonian graphs that we constructed have a much smaller diameter than that of those constructed previously by Mukhopadhyaya and Sinha, Harary and Hayes, and Wang et al. © 2001 John Wiley & Sons, Inc.
Pharmacological evidence for GABAergic regulation of specific behaviors inDrosophila melanogaster
Authors: Leal Sandra M. , Neckameyer Wendi S.
Published: August 2002

We have identified several GABAergic‐modulated behaviors inDrosophila melanogasterby employing a pharmacological approach to disrupt GABA transporter functionin vivo. Systemic treatment of adult female flies with the GABA transport inhibitorsDL‐2,4‐diaminobutyric acid (DABA) or R,S‐nipecotic acid (NipA), resulted in diminished locomotor activity, deficits in geotaxis, and the induction of convulsive behaviors with a secondary loss of the righting reflex. Pharmacological evidence suggested that the observed behavioral phenotypes were specific to disruption of GABA transporter function and GABAergic activity. The effects of GABA reuptake inhibitors on locomotor activity were dose dependent, pharmacologically distinct, and paralleled their known effects in mammalian systems. Recovery of normal locomotor activity and the righting reflex in DABA‐ and NipA‐treated flies was achieved by coadministration of bicuculline (BIC), a GABA receptor antagonist that supresses GABAergic activity in mammals. Recovery of these behaviors was also achieved by coadministration of gabapentin, an anticonvulsant agent that interacts with mammalian GABAergic systems. Finally, behavioral effects were selective because other specific behaviors such as feeding activity and female sexual receptivity were not affected. Related pharmacological analyses performedin vitroon isolatedDrosophilasynaptic plasma membrane vesicles demonstrated high affinity, saturable uptake mechanisms for [3H]‐GABA; further competitive inhibition studies with DABA and NipA demonstrated their ability to inhibit [3H]‐GABA transport. The existence of experimentally accessible GABA transporters inDrosophilathat share conserved pharmacological properties with their mammalian counterparts has resulted in the identification of specific behaviors that are modulated by GABA. © 2002 Wiley Periodicals, Inc. J Neurobiol 50: 245–261, 2002; DOI 10.1002/neu.10030
Decreased calretinin expression in cerebellar granule cells in the leaner mouse
Authors: Nahm Sang‐Soep , Tomlinson Dana J. , Abbott Louise C.
Published: August 2002

We investigated calretinin expression in cerebellar granule cells of 30‐day‐old leaner mice to understand possible changes in calcium homeostasis due to the calcium channel mutation that these mice carry. Quantitative in situ hybridization histochemistry showed decreased calretinin mRNA expression in the leaner cerebellum. Immunohistochemical staining also revealed decreased calretinin immunoreactivity in the leaner cerebellum. To exclude the effect of granule cell loss that occurs in the leaner mouse when comparing cerebellar calretinin expression, the number of granule cells per unit area in the cerebellum was compared to the wild‐type cerebellum. Granule cell counts per unit area of cerebellum revealed similar numbers of granule cells present in wild‐type and leaner mice. Laser capture microdissection (LCM) was employed to obtain an equal number of granule cells from wild‐type and leaner mice. Western blot analysis with LCM‐procured cerebellar granule cells showed decreased calretinin expression in leaner granule cells. These results indicate that there is an absolute decrease in calretinin expression in leaner granule cells even when granule cell loss is taken into account. Decreased calretinin expression in leaner granule cells may contribute to altered calcium buffering capacity. This alteration could be an adaptive change due to the calcium channel dysfunction, and may result in abnormal neuronal excitability and gene expression. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 313–322, 2002
NMDA receptor regulation of cell death in the rat olfactory bulb
Authors: Fiske Brian K. , Brunjes Peter C.
Published: August 2002

Cell death is widespread in the developing nervous system and is under complex regulation by numerous intra‐ and intercellular mechanisms. Blockade of the N‐methyl‐D‐aspartate (NMDA) subtype of glutamate receptor has been shown to promote cell death in the developing brain (Ikonomidou et al., 1999), suggesting that afferent functional activation is an important regulator of cell survival. The olfactory bulb, the first central relay for olfactory information from the nose, is well suited for examining the role of afferent activity in neuronal development. Functional deprivation is easily performed by surgical blockade of airflow to one side of the nasal passage, which results in dramatic alterations in postnatal development of the bulb (Brunjes, 1994), including enhanced neuronal loss (Frazier and Brunjes, 1988; Najbauer and Leon, 1995). The present report examined the specific role of NMDA receptor activation in regulating cell survival within the rat bulb. Pharmacological blockade of receptors with the noncompetitive channel blocker MK‐801 (3 × 0.5 mg/kg i.p.) resulted in profound increases in cell death within 24 h. Furthermore, in contrast to other regions, where the effects of receptor blockade were confined to the first 2 postnatal weeks (Ikonomidou et al., 1999), enhancement of cell death was seen in the deeper granule cell‐containing regions of the bulb with injections as late as postnatal day 28. In addition, the effects of MK‐801 were much more dramatic than those seen after unilateral naris closure, suggesting that NMDA receptor activation may mediate additional survival pathways in the bulb beyond that provided by first nerve input. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 223–232, 2001
Barrier variational generation of quasi‐isometric grids
Authors: Garanzha V. A.
Published: August 2002

A grid generation method based on the minimization of the discrete barrier functional with feasible set consisting of quasi‐isometric grids is suggested. The deviation from isometry for given grid connectivity and prescribed boundary conditions is minimized via the contraction of the feasible set into a small vicinity of the optimal grid. Formulation of functional with given metrics in both physical and logical spaces allows to consider the adaptive grid generation in terms of quasi‐isometric grids and cover many practical applications. A fast and reliable grid untangling procedure based on the penalty‐like reformulation of barrier functional and the continuation technique is described. Numerical experiments demonstrate that the suggested functional produces high‐quality grids with small global condition numbers. Copyright © 2001 John Wiley & Sons, Ltd.
An inverse eigenvalue method for frequency isolation in spring–mass systems
Authors: Egaña Juan C. , Kuhl Nelson M. , Santos Luis C.
Published: August 2002

The action of external vibrating forces on mechanical structures can cause severe damages when resonance occurs. The removal of natural frequencies of the structure from resonance bands is therefore of great importance. This problem is called frequency isolation problem and is the subject of this paper. A new inverse eigenvalue method is proposed and applied to spring–mass systems, which have generated much interest in the literature as prototypes of vibrating structures. The novelty of the method lies in using the zeros of the frequency response function at the last mass as control variables in an optimization problem to minimize the impact of redesign. Numerically accurate algorithms for computing the sensitivity with respect to the control variables are presented, which form the basis of an efficient multidimensional search strategy to solve the frequency isolation problem. Copyright © 2001 by John Wiley & Sons, Ltd.
Decoupling preconditioners in the implicit parallel accurate reservoir simulator (IPARS)
Authors: Lacroix Sébastien , Vassilevski Yuri V. , Wheeler Mary F.
Published: August 2002

This paper presents an overview of two‐stage decoupling preconditioning techniques employed in the implicit parallel accurate reservoir simulator (IPARS) computational framework for modelling multi‐component multi‐phase flow in porous media. The underlying discretization method is implicit Euler in time and mixed finite elements or cell‐centred finite differences in space. IPARS permits rigorous, physically representative coupling of different physical and numerical flow models in different parts of the domain and accounts for structural discontinuities; the framework currently includes eight physical models. For simplicity of exposition, we have restricted our discussion to a two‐phase oil–water model and a three‐phase black oil model. Our decoupling approach involves extracting a pressure equation from the fully coupled linearized system thus allowing for a more accurate preconditioning of a discrete elliptic problem of lower dimension. Copyright © 2001 John Wiley & Sons, Ltd.
Kinematically admissible meshless approximation using modified weight function
Authors: Kang Myung‐Seok , Youn Sung‐Kie
Published: August 2002

In meshless methods, in general, the shape functions do not satisfy Kronecker delta properties at nodal points. Therefore, imposing essential boundary conditions is not a trivial task as in FEM. In this regard, there has been a great deal of endeavor to find ways to impose essential boundary conditions. In this study, a new scheme for imposing essential boundary conditions is developed. Weight functions are modified by multiplying with auxiliary weight functions and the resulting shape functions satisfy Kronecker delta properties on the boundary nodes. In addition, the resulting shape functions possess linear interpolation features on the boundary segments where essential boundary conditions are prescribed. Therefore, the essential boundary conditions can be exactly satisfied with the new method. More importantly, the imposition of essential boundary conditions using the present method is infinitely easy as in the finite element method. Numerical examples show that the method also retains high convergence rate comparable to the Lagrange multiplier method. Copyright © 2001 John Wiley & Sons, Ltd.
Frequency‐domain analysis of time‐integration methods for semidiscrete finite element equations—part II: Hyperbolic and parabolic–hyperbolic problems
Authors: Muğan Ata , Hulbert Gregory M.
Published: August 2002

Time‐integration methods for semidiscrete finite element equations of hyperbolic and parabolic– hyperbolic types are analysed in the frequency domain. The discrete‐time transfer functions of six popular methods are derived, and subsequently the forced response characteristics of single modes are studied in the frequency domain. Three characteristic numbers are derived which eliminate the parameter dependence of the frequency responses. Frequency responses and L2‐norms of the phase and magnitude errors are calculated, and comparisons are given of the methods. As shown; the frequency‐domain analysis explains all time‐domain properties of the methods, and gives more insight into the subject. Copyright © 2001 John Wiley & Sons, Ltd.
Application of upper bound method to the powder‐forging of cup‐shaped axisymmetric preforms for estimating punch load
Authors: Cho J. R. , Jeong H. S.
Published: August 2002

This paper is concerned with the analytic derivation of the punch load required to forge cup‐shaped axisymmetric porous preforms. Splitting the two‐dimensional preform domain into three rectangular regions, we assumed the kinematically admissible velocity fields to apply the upper bound method. According to the resulting formulas, we developed an incremental numerical algorithm for computing time‐discretized step‐wise punch loads and preform volumes. In order to illustrate the validity of the proposed estimate, we compared the numerical results obtained by the present analysis with those by the finite element simulation. From the comparison made through different preform dimensions, we observed that the present analysis expects the reliable upper bounds of process step‐wise punch loads. Copyright © 2001 John Wiley & Sons, Ltd.
A variance propagation algorithm for stochastic heat and mass transfer problems in food processes
Authors: Scheerlinck Nico , Verboven Pieter , Stigter Johannes D. , De Baerdemaeker Josse , Van Impe Jan F. , Nicolai Bart M.
Published: August 2002

A variance propagation algorithm for stochastic coupled heat and mass transfer problems subjected to first order autoregressive random process boundary conditions was developed. The algorithm is based on the finite element formulation of Luikov's coupled heat and mass transfer equations and involves the numerical solution of coupled Lyapunov and Sylvester matrix differential equations. It offers a cheap alternative to the Monte Carlo method for the computation of the mean value and variance of the temperature and moisture content field. The algorithm is generally applicable and can easily be inserted in any existing finite element code. Also, it can be extended to other types of random processes. The algorithm was applied to analyse the drying of a soybean kernel. Simulation results show that random fluctuations of the process conditions may cause considerable variability of the temperature and the moisture content within the drying soybean kernel. This is an important feature to take into account for the design of a drying process, and for thermal food processes in general. Copyright © 2001 John Wiley & Sons, Ltd.
Iterative solution of large‐scale acoustic scattering problems with multiple right hand‐sides by a domain decomposition method with Lagrange multipliers
Authors: Tezaur Radek , Macedo Antonini , Farhat Charbel
Published: August 2002

An extension of the FETI‐H method is designed for the solution of acoustic scattering problems with multiple right‐hand sides. A new local pre‐conditioning of this domain decomposition method is also presented. The potential of the resulting iterative solver is demonstrated by numerical experiments for two‐dimensional problems with high wavenumbers, as many as 2.5 million complex degrees of freedom, and a sweep on the angle of the incident wave. Preliminary results for a three‐dimensional submarine problem are also included. The FETI‐H method, whose numerical scalability with respect to the mesh and subdomain sizes was previously established, is shown here to be also numerically scalable with respect to the wavenumber. Copyright © 2001 John Wiley & Sons, Ltd.
An improved weighting method with multibounds formulation and convex programming for multicriteria structural optimization
Authors: Zhang W. H. , Domaszewski M. , Fleury C.
Published: August 2002

This paper presents an improved weighting method for multicriteria structural optimization. By introducing artificial design variables, here called as multibounds formulation (MBF), we demonstrate mathematically that the weighting combination of criteria can be transformed into a simplified problem with a linear objective function. This is a unified formulation for one criterion and multicriteria problems. Due to the uncoupling of involved criteria after the transformation, the extension and the adaptation of monotonic approximation‐based convex programming methods such as the convex linearization (CONLIN) or the method of moving asymptotes (MMA) are made possible to solve multicriteria problems as efficiently as for one criterion problems. In this work, a multicriteria optimization tool is developed by integrating the multibounds formulation with the CONLIN optimizer and the ABAQUS finite element analysis system. Some numerical examples are taken into account to show the efficiency of this approach. Copyright © 2001 John Wiley & Sons, Ltd.
A large‐strain elasto–plastic shell formulation using the Morley triangle
Authors: Kolahi A. S. , Crisfield M. A.
Published: August 2002

The paper describes a large‐strain elasto–plastic formulation for shells, which is based on the faceted ‘Morley triangle’, with rotation variables only being provided at each mid‐side in the form of a rotation about the side.A co‐rotational formulation is adopted, with the local deformation gradient being obtained from a polar decomposition using F=RU. The material description is then based around ‘logeU’, with U being decomposed into principal directions. Plasticity is treated with the aid of the multiplicative F=FeFp. In contrast to many earlier formulations with the Morley triangle, the current formulation is invariant to the node numbering. In order to achieve this invariance, it is necessary to re‐visit the origins of the Morley triangle and to re‐cast the formulation as a special form of ‘discrete‐Kirchhoff approach’. The associated constraint is now applied in relation to the ‘current configuration’. Copyright © 2001 John Wiley & Sons, Ltd.
An efficient parallel procedure for the simulation of crack growth using the cohesive surface methodology
Authors: Lingen F. J. , Tijssens M. G. A.
Published: August 2002

Simulations of crack growth that are based on the cohesive surface methodology typically involve ill‐conditioned systems of equations and require much processing time. This paper shows how these systems of equations can be solved efficiently by adopting the domain decomposition approach in which the finite element mesh is partitioned into multiple blocks. The system of equations is then reduced to a much smaller system of equations that is solved with an iterative algorithm in combination with a powerful two‐level preconditioner. Although the solution algorithm is more efficient than a direct solution algorithm on a single‐processor computer, it becomes really attractive when used on a parallel computer. This is demonstrated for a large scale simulation of crack growth in a polymer using a Cray T3E with 64 processors. Copyright © 2001 John Wiley & Sons, Ltd.
Fully stressed frame structures unobtainable by conventional design methodology
Authors: Mueller Keith M. , Burns Scott A.
Published: August 2002

A structure is said to be fully stressed if every member of the structure is stressed to its maximum allowable limit for at least one of the loading conditions. Fully stressed design is most commonly used for small and medium size frames where drift is not a primary concern. There are several potential methods available to the engineer to proportion a fully stressed frame structure. The most commonly used methods are those taught to all structural engineering students and are very easy to understand and to implement. These conventional methods are based on the intuitive idea that if a member is overstressed, it should be made larger. If a member is understressed, it can be made smaller, saving valuable material.

It has been found that a large number of distinct fully stressed designs can exist for a single frame structure subjected to multiple loading conditions. This study will demonstrate that conventional methods are unable to converge to many, if not most, of these designs. These unobtainable designs are referred to as ‘repellers’ under the action of conventional methods. Other, more complicated methods can be used to locate these repelling fully stressed designs. For example, Newton's method can be used to solve a non‐linear system of equations that defines the fully stressed state. However, Newton's method can be plagued by divergence and also by convergence to physically meaningless solutions. This study will propose a new fully stressed design technique that does not have these problems. Copyright © 2001 John Wiley & Sons, Ltd.
Higher‐order boundary element methods for transient diffusion problems. Part I: Bounded flux formulation
Authors: Grigoriev M. M. , Dargush G. F.
Published: August 2002

Despite the significant number of publications on boundary element methods (BEM) for time‐dependent problems of heat diffusion, there still remain issues that need to be addressed, most importantly accuracy of the numerical modelling. Although very precise for steady‐state problems, the common boundary element methods applied to transient problems do not yield highly accurate numerical solutions. This paper investigates the reasons that prohibit achievement of a high level of accuracy for transient heat diffusion problems with continuous temperature and bounded heat flux solutions. In order to greatly enhance the commonly used boundary element formulations, we propose higher‐order time interpolation functions, including quadratic and quartic approximations. We show that the use of higher‐order time functions greatly reduces the numerical error concentrated in the corner regions, and results in very good uniformity of the flux and temperature distributions along the boundaries for problems where uniform distributions are expected.

In order to highlight the importance of proper resolution both in time and space for the transient problems, we consider one‐ and two‐dimensional formulations in this paper. High‐order boundary elements using quartic shape functions, as well as high‐order bi‐quartic volume cells, are used to attain mesh‐independent numerical solutions. We consider four transient heat diffusion problems that possess exact solutions to investigate the convergence rate and accuracy of the higher‐order boundary element formulations. A very high level of accuracy is possible for both one‐ and two‐dimensional formulations. Additionally, we show that the accuracy of a commercially available finite‐element code is far less than that of the boundary element methods for a given spatial and temporal discretization. Copyright © 2002 John Wiley & Sons, Ltd.
A parallel computational method in steady power‐law creep
Authors: Klebanov I. M. , Davydov A. N.
Published: August 2002

A new approach to parallelization of materially non‐linear problems in solid mechanics is developed. It is based on approximating generalized models of subdomains. The procedure does not retain the same substructuring technique used in a linear version. The convergence proof of the single‐ and multilevel‐domain decomposition algorithms uses the principle of minimum potential energy dissipation and investigated properties of the substructural models. The high efficiency of the approach introduced is shown through the study of several examples. The method developed in this paper for steady creep can be used without modification to solve non‐linear elasticity problems and, at active loading, plasticity problems for bodies of the power‐law strain–stress diagrams. Copyright © 2001 John Wiley & Sons, Ltd.
A generalized recursive formulation for constrained flexible multibody dynamics
Authors: Bae D. S. , Han J. M. , Choi J. H. , Yang S. M.
Published: August 2002

This research develops a relative co‐ordinate formulation for the multibody flexible dynamics. The velocity transformation method is notationally compact, because the Cartesian generalized velocities are simultaneously transformed to the relative generalized velocities in a matrix form. However, inherent computational efficiency in the recursive kinematics between two adjacent bodies has not been exploited. This research presents a recursive formulation which is both notationally compact and computationally efficient. The velocity transformation method is used to derive the equations of motion and their derivatives. Matrix operations associated with the velocity transformation matrix in the resulting equations of motion and their derivatives are classified into several categories. A joint library of the generalized recursive formulas is developed for each category. When one category is encountered in implementing the equations of motion and their derivatives, the corresponding recursive formulas in the category are invoked. When a new force or joint module is added to a general purpose programme in the relative co‐ordinate formulation, the modules for the rigid body are not reusable for the flexible body. Since the flexible body dynamics handles additional generalized co‐ordinates associated with deformation, implementation of the flexible dynamics is generally complicated and prone to coding mistakes. A virtual rigid body is introduced at every joint and force reference frames. A virtual flexible body joint is introduced between two body reference frames of the virtual and original bodies. This makes a flexible body subjected to only the kinematic admissibility condition for the virtual flexible body joint. As a result, the only extra work to handle the flexible bodies is to add the virtual flexible body joint modules in all recursive formulas. Since computation time in a relative co‐ordinate formulation is approximately proportional to the number of relative co‐ordinates, computational overhead due to the additional virtual bodies and joints are minor. Meanwhile, implementation convenience is dramatically improved. Copyright © 2001 John Wiley & Sons, Ltd.
Rapid Skill Obsolescence in an IT Company: A Case Study of Acxiom Corporation
Authors: Standridge Jeff , Autrey Ramona
Published: August 2002

Although most employees in this fast‐changing business world need to keep their skills up‐to‐date, nowhere is this requirement as essential as among information technology workers. At Acxiom Corporations, an IT company, this need was pressing. And the firm found that reliance on the classic KSA—knowledge, skills, and abilities—measures was not meeting the need. Instead, it took a broader look at corporate goals and how its people could meet them—and has linked targeted behaviors to the achievement of those goals, making them the basis for career development, performance, evaluation, and compensation. © 2001 by John Wiley & Sons, Inc.
Strategic adaptation to change: A practical system for achieving breakthrough performance
Authors: Stein Martin M.
Published: August 2002

One of the best ways to understand the value of and need for organizational learning is to begin by setting a
goal. Then examine the organizational barriers to achieving it—and design the policies, programs, and
practices that will overcome them. This process, properly sustained, can continuously upgrade an
organization's core competencies and intellectual capital. People get energized, knowledge gets communicated
and applied, and change becomes a challenge rather than a threat. © 2002 Wiley Periodicals,
Inc.
A wake‐up call for not only terrorist threats
Authors: Viollis Paul
Published: August 2002

The terrorist attacks of September 11 underscore the omnipresent threats posed to employers. In addition to
those to our personal and national security from terrorists, incidents of workplace violence have increased more
than 750 percent in the last three years. The onus is on each organizational leader and business professional to
closely scrutinize this epidemic of violence, uncover the common denominators, and expeditiously formulate
solutions before tragedy strikes. We must embrace a new corporate environment free of the full range of recognized
hazards. © 2002 Wiley Periodicals, Inc.
Obstacles—and Overcoming Them—to Leadership Among Professional Workers
Authors: Fisher Jr. James R.
Published: August 2002

It's not news that, over the past few decades, the heart of the U.S. workforce has traded blue collars for white. Management, the author argues, has not changed commensurately. He outlines the need for leadership to replace traditional top‐down management, identifies obstacles to leadership by professional workers and discusses how those obstacles can, and must, be overcome. © 2001 John Wiley & Sons, Inc.
What Companies Do Beyond the Basics To Retain Scarce Talent
Authors: Herman Roger E. , Gioia‐Herman Joyce L.
Published: August 2002

Most companies are suffering from staffing difficulties, increasing the importance of employee retention. Creative approaches are giving many employers a competitive edge in the war for talent. Examples of the strategies of enlightened employers offer models to follow and may stimulate some refreshing ideas. © 2001 John Wiley & Sons, Inc.
Blocking of carbachol‐induced calcium mobilization by glutamate receptor antagonists
Authors: Naarala Jonne , Tervo Pirkko , Loikkanen Jarkko , Savolainen Kai
Published: August 2002

The aim of this study was to explore whether glutamatergic‐ and muscarinic cholinergic receptor systems have interactions in controlling intracellular calcium concentrations. We report here that cholinergic receptor‐stimulated elevations of intracellular calcium can be blocked dose‐dependently by N‐methyl‐D‐aspartate (NMDA) and metabotropic glutamate receptor antagonists, but not by an AMPA/kainate antagonist, in human SH‐SY5Y neuroblastoma cells. It seems likely that cholinergic and glutamatergic receptor classes may be under partial control of each other. There are number of in vivo observations to suggest that, in addition to cholinergic system, also other neurotransmitter systems are involved in cholinergic neuronal excitation and subsequent convulsions. The SH‐SY5Y cell line may prove to be a useful in vitro model to study cholinergic and glutamatergic interactions.
The spatial pattern of the vacuolation (‘spongiform change’) in the cerebral cortex in variant Creutzfeldt‐Jakob disease (vCJD)
Authors: Armstrong R. A. , Cairns N. J. , Ironside J. W. , Lantos P. L.
Published: August 2002

The spatial pattern of the vacuolation (‘spongiform change’) was studied in areas of the cerebral cortex in 11 cases of variant Creutzfeldt‐Jakob disease (vCJD). The vacuoles were evenly distributed along the cortex in 40/106 (38%) areas studied and randomly distributed in 6/106 (5.6%) areas. In 22/106 (21%) areas, the vacuoles were aggregated into clusters, 50–1600 μm in diameter and which were distributed in a regular pattern parallel to the pia mater. In 38/106 (36%) areas, large clusters of vacuoles, at least 1600 μm in diameter, were present. No significant differences in spatial patterns were observed between the different cortical regions or between the upper and lower laminae. In addition, age at onset and duration of the disease had no significant affect on spatial patterns. The spatial distribution of the vacuolation contrasts with that reported in sporadic CJD (sCJD) suggesting a different pattern of cortical degeneration in vCJD.
Tetraethylammonium‐induced changes in intracellular calcium in Alzheimer donor fibroblasts
Authors: Brzyska Maria , Michalski Andrzej , Elbaum Danek
Published: August 2002

In this paper we analyzed the operation of K+ channels by measuring the extracellular calcium influx in response to tetraethylammonium (TEA) depolarization. We compared TEA‐induced intracellular calcium changes in fibroblasts obtained from Alzheimer Disease (AD) patients, aged (AC) and young (YC) healthy subjects. Subsequently we analyzed the effects of incubation of these fibroblasts with beta‐amyloid on calcium responses. Our results indicated that depolarization with TEA did not abolish calcium responses in any of the tested cell groups. TEA‐elicited calcium changes in AD cells were significantly greater than those observed in AC or YC cells. Responses were delayed in AD fibroblasts with respect to AC or YC cells. Incubation with beta‐amyloid did not alter the other effects: response amplitude in AD cells was still greater than in AC or YC cells; AD responses were still delayed with respect to AC and YC responses. These results support the earlier findings that calcium responses were altered in AD cells but suggest their delay rather than inhibition.
Sulfatide does not induce apoptosis in arylsulfatase A‐deficient cells
Authors: Habetha Matthias
Published: August 2002

Deficiency of arylsulfatase A (ASA) causes metachromatic leukodystrophy (MLD). Patients suffering from this inherited disease show reduced or complete loss of ability to degrade sulfatide. Sulfatide is an abundant lipid of mammalian cellular membrances and preferentially localised in brain tissue. Neurological symptoms of MLD‐patients, therefore, may be caused by increased amoounts of cellular sulfatide. In the present study I have tested this idea by treating various cell lines with sulfatide and examining the rate of apoptosis. Four mammalian cell lines including the mouse glial cell lines 11+/+C1 and ASA‐deficient 17–/–A1 have been used. I show that exogenously applied sulfatide was incorporated and intracellularly stored in these cells. Incorporation of sulfatide was at a lower level in the presence of recombinant ASA. FACS analysis of propidiumiodide stained cells revealed that treatment of cells with sulfatide had no effect on apoptosis.
Tonotopic mapping of c‐fos expression in the dorsal cochlear nucleus of the hamster
Authors: Bahu Samer J. , Kaltenbach James A. , Zhang Jinsheng , Khariwala Samir S. , Afman Chad E. , Hnatiuk Mark
Published: August 2002

We used the hamster as a model for identifying frequency specific loci in the dorsal cochlear nucleus (DCN) using c‐fos immunocytochemistry. Animals were divided into three groups. The animals in the first group were stimulated with tone bursts at a frequency of 5kHz, those in the second group at 10kHz, and those in the third at 17kHz. The bursts were 50 msecs in duration and were presented for 1 hour at 67 dB SPL (4/sec). Brain tissue was obtained and procedures for c‐fos assay were performed. Following stimulation distinct clusters of immunolabeled nuclei were found within the DCN. Cluster locations varied as a function of frequency. For the 5 kHz stimulus group, clusters were found at a mean position of 33% of the distance from the lateral to the medial extremities of the DCN. For exposures of 10 kHz, the bands were positioned approximately 50% of this distance, and for 17 kHz at approximately 67% of the lateral to medial distance. These results are consistent with the pattern of tonotopic organization which has been demonstrated in the DCN using electrophysiological procedures.
An adaptive displacement/pressure finite element scheme for treating incompressibility effects in elasto‐plastic materials
Authors: Suttmeier Franz–Theo
Published: August 2002

In this article, a mixed finite element formulation is described for coping with (nearly) incompressible behavior in elasto‐plastic problems. In addition to the displacements, an auxiliary variable, playing the role of a pressure, is introduced resulting in Stokes‐like problems. The discretization is done by a stabilized conforming Q1/Q1‐element, and the corresponding algebraic systems are solved by an adaptive multigrid scheme using a smoother of block Gauss–Seidel type. The adaptive algorithm is based on the general concept of using duality arguments to obtain weighted a posteriori error bounds. This procedure is carried out here for the described discretization of elasto‐plastic problems. Efficiency and reliability of the proposed adaptive method is demonstrated at (plane strain) model problems. © 2001 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 17:369–382, 2001
An optimal‐order error estimate for MMOC and MMOCAA schemes for multidimensional advection‐reaction equations
Authors: Wang Hong
Published: August 2002

In this article, we analyze the modified method of characteristics (MMOC) and an improved version of the MMOC, named the modified method of characteristics with adjusted advection (MMOCAA), for multidimensional advection‐reaction transport equations in a uniform manner. We derive an optimal‐order error estimate for these schemes. Numerical results are presented to verify the theoretical estimates. © 2002 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 18: 69–84, 2002
Clinical trials in the 21st century: The case for participant‐centered research¶
Authors: Gross Deborah , Fogg Louis
Published: August 2002

Informed consumers of the 21st century increasingly will be hesitant to enroll in randomized clinical trials (RCTs) because they will be unwilling to (a) submit to random assignment; (b) complete assessments that are too lengthy, intrusive, or irrelevant; or (c) comply with protocols that do not meet their needs. Research centered on the needs and interests of participants is likely to engender greater participation and commitment than are traditional RCTs. Recommendations for making clinical trials more participant centered include: (a) expanding our conceptualizations of study validity, (b) involving consumers as advisers in the development and execution of clinical trials, and (c) offering participants reasonable alternatives to random assignment. © 2001 John Wiley & Sons, Inc. Res Nurs Health 24:530–539, 2001
Occipital perforations in a late neolithic probable aurochs (Bos primigenius bojanus) cranium from Letchworth, Hertfordshire, UK
Authors: Baxter Ian L.
Published: August 2002

An example of ante‐mortem occipital perforations in the cranium of a probable aurochs (Bos primigenius) cow from a late Neolithic archaeological site at Letchworth, Hertfordshire is presented. This is the second reported occurrence thus far of cranial perforations in a wild bovid and lends support to a congenital cause of the condition in archaeological domestic cattle skulls. Copyright © 2002 John Wiley & Sons, Ltd.
The role of cetacea in prehistoric and historic Atlantic Scotland
Authors: Mulville Jacqui
Published: August 2002

Whalebone has been recovered from many archaeological sites in Atlantic Scotland. Through an examination of material excavated from the Western Isles (Outer Hebrides) this paper explores the methods by which whales and whalebone were procured. Using historical and ethnographic data the possibility that cetaceans were naturally stranded or actively hunted is considered, and for the latter the methods of capture are discussed. The ways in which whale carcasses were utilized: as meat, blubber, skins, artefacts and as an architectural material, is examined through the analysis of archaeozoological material. Using these data the value of whales and whale bone in the islands can be determined. The potential for further study is discussed in the light of the growing volume of material available for study and advances in scientific techniques such as DNA analysis. Copyright © 2002 John Wiley & Sons, Ltd.
Unified approach to linear quadratic regulator with time‐scale property
Authors: Singh Hardev , Brown Ronald H. , Subbaram Naidu D.
Published: August 2002

A method for decomposition of unified (continuous/discrete) linear quadratic regulator with two‐time‐scale property is presented. The composite and the reduced‐order controls are formulated in standard unified domain. By appropriate transformations, it is shown that the results of continuous‐time (CT) and discrete‐ time (DT) obtained previously using two separate techniques, can be obtained by this single unified technique. With this method, there is no need to consider two‐time scale systems in continuous and the discrete domains separately. This paper also presents some numerical examples to illustrate the theoretical results. Copyright © 2001 John Wiley & Sons, Ltd.
Optimal weighting design for distributed parameter systems estimation
Authors: Ouarit Mostafa , Yvon Jean‐Pierre , Henry Jacques
Published: August 2002

This paper presents a method which aims at improving parameter estimation in dynamical systems. The general principle of the method is based on a modification of the least‐squares objective function by means of a weighting operator, in view to improve the conditioning of the identification problem. First we recall a previous work using variational calculus in order to obtain the weighting operators through a linear equation. Then we propose a new approach which consists of determining the weights by formulating an optimization problem including positive semidefinite constraints (linear matrix inequalities, LMI). Copyright © 2001 John Wiley & Sons, Ltd.
Restricted structure control of multiple model systems with Series 2 DOF tracking and feedforward action
Authors: Grimble M. J.
Published: August 2002

The solution of a scalar optimal control problem is discussed where the feedback, series tracking and feedforward controllers are chosen to have a very simple. Each controller term may be chosen to be of reduced order, lead/lag, or PID forms, and the controller is required to minimize an LQG cost‐index. The optimization is based upon a cost‐function which also allows separate costing of the terms due to the feedback, tracking and feedforward controllers. The system model can be uncertain and can be represented by a set of models over which the optimization is performed. This provides a form of robust optimal control that might even be applied to non‐linear systems that can be approximated by a set of linearized models.

The theoretical problem considered is to obtain the causal, stabilizing, feedback, series‐tracking and feedforward controllers, of a prespecified form, that minimize an LQG criterion over the set of possible linear plant models. The underlying practical problem of importance is to obtain a simple method of tuning low‐order controllers, given only an approximate model of the process. The results are illustrated in a power generation control problem for a system represented by 12 different linearized plant models. The single feedback controller that is obtained has a simple form and stabilizes the full set of models. Copyright © 2001 John Wiley & Sons, Ltd.
Seeing eye to eye: organizational behaviour, brokering and building trust in Tanzania
Authors: Hewitt Tom , Wangwe Sam , Wield David
Published: August 2002

The focus of this article is organizational behaviour in and around the private sector in Tanzania at a time of transition through liberalization and the promotion of private sector activity; how the private sector has re‐emerged in the very recent past; how it operates as a group or, more accurately, as a set of groups, and the relationships between its component parts and with other development organizations (notably public actors: the state and aid donors). Within this framework our interest is in how organizational behaviour is mediated and trust is built through the brokering of relations between different organizations which intersect the public and private (and what this means for the public sphere). The article assesses the usefulness of a three‐level framework for analysing organizational and institutional transformation, shows that some tentative but modest change is occurring, and that a range of incomplete but positive political processes are happening. We show that institutional development is the weak link in these processes. Copyright © 2002 John Wiley & Sons, Ltd.
School vouchers and academic performance: results from three randomized field trials
Authors: Howell William G. , Wolf Patrick J. , Campbell David E. , Peterson Paul E.
Published: August 2002

This article examines the effects of school vouchers on student test scores in New York, New York, Dayton,
Ohio, and Washington, DC. The evaluations in all three cities are designed as randomized field trials. The
findings, therefore, are not confounded by the self‐selection problems that pervade most observational
data. After 2 years, African Americans who switched from public to private school gained, relative to their
public‐school peers, an average of 6.3 National Percentile Ranking points in the three cities on the Iowa
Test of Basic Skills. The gains by city were 4.2 points in New York, 6.5 points in Dayton, and 9.2 points in
Washington. Effects for African Americans are statistically significant in all three cities. In no city are
statistically significant effects observed for other ethnic groups, after either 1 or 2 years. © 2002 by
the Association for Policy Analysis and Management.
Synthesis and magnetic properties of poly(p‐phthaloyl‐disacetylaceton‐ethylenediimine) metal complexes
Authors: Wang Yun‐Pu , Chai Chun‐Peng , Wang Rong‐Min
Published: August 2002

Macrocyclic Schiff‐base ligand, bisacetylaceton‐ethylenediimine (BAE) and its transition metal complexes M(BAE) (M = Cu2+, Ni2+) were synthesized. The complexes having characteristics of aromatic systems and well‐defined one‐dimensional structures, reacted with p‐phthaloyl chloride, to obtain polymer complexes. The complexes were characterized by elemental analysis, inductively coupled plasma (ICP), FT‐IR, and thermal analysis and show good thermal stability. ESR spectra analysis discovered that there are free radicals in the chain of polymers, indicating that a weak magnetic spin‐exchange interaction operates between the metal ions and free radicals. It is found that, as the bridging p‐phthaloyl group is able to propagate the magnetic exchange interaction, the polymer complexes show paramagnetic properties by measurement of temperature dependence of the magnetic property, and obey Curie–Weiss law. Copyright © 2001 John Wiley & Sons, Ltd.
Monodispersed polystyrene latex particles functionalized by the macromonomer technique. II. Application in immunodiagnosis
Authors: Gibanel Sebastien , Heroguez Valerie , Gnanou Yves , Aramendia Esteban , Bucsi Alexander , Forcada Jacqueline
Published: August 2002

Monodispersed polymer colloids with aldehyde and acetal functionalities, introduced by the macromonomer technique, were synthesized by a two‐step emulsion polymerization process. The latex samples so formed were chosen as the polymeric support to carry out covalent coupling with the antibody IgG anti‐C reactive protein, to test the utility of the latex–protein complexes formed in immunoassays. More than the 45% of the initially linked protein was covalently coupled in the acetal latex samples. Copyright © 2001 John Wiley & Sons, Ltd.
Controlled, micro‐scale film formation of waterborne dispersions
Authors: Krupers Maarten J. , Fischer Hartmut R. , Schuurman Arjan G.A. , Vercauteren Frank F.
Published: August 2002

The film formation on a micro‐scale of latex material is described. Waterborne polymer dispersions dried below their Tg are treated by laser or direct heat treatment by means of a tip (diameter 5 µ m) of a micro thermal analysis apparatus (µ ‐TA). Both methods give a linewidth, line thickness and dot‐sizes in the micron range. The layer thickness decreases during fusion of the particles because of the loss of voids during film formation. Non treated areas can be washed away selectively. Laser treatment gives a more smooth surface than direct thermal treatment with a µ‐TA tip. Copyright © 2001 John Wiley & Sons, Ltd.
Comparison of fuel cell performance of selected fluoropolymer and hydrocarbon based grafted copolymers incorporating acrylic acid and styrene sulfonic acid
Authors: Horsfall J. A. , Lovell K. V.
Published: August 2002

Fuel cell tests have been carried out on ion exchange membranes produced by the radiation grafting of either acrylic acid or styrene monomers (followed by a sulphonation reaction) onto selected hydrocarbon and fluoropolymer films. Relationships between the membranes' intrinsic properties, composition, ion exchange capacity and equilibrium water content and their respective fuel cell performance have been established. Copyright © 2002 John Wiley & Sons, Ltd.