bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conditional ablation of neurones in transgenic mice
Authors: Isles Anthony R. , Ma Dan , Milsom Chloe , Skynner Michael J. , Cui Wei , Clark John , Keverne Eric B. , Allen Nicholas D. 
Published: August 2002

AbstractConditional targeted ablation of specific cell populations in living transgenic animals is a very powerful strategy to determine cell functions in vivo. This approach would be of particular value to study the functions of distinct neuronal populations; however, the transgene of choice for conditional cell ablation studies in mice, the herpes simplex virus thymidine kinase gene, cannot be used to ablate neurones as its principal mode of action relies on cell proliferation. Here we report that expression of the E.coli nitroreductase gene (Ntr) and metabolism of the prodrug CB1954 (5‐aziridin‐1‐yl‐2‐4‐dinitrobenzamide) to its cytotoxic derivative can be used to conditionally and acutely ablate specific neuronal populations in vivo. As proof of principal, we have ablated olfactory and vomeronasal receptor neurones by expressing Ntr under the control of the olfactory marker protein (OMP) gene promoter. We demonstrate that following CB1954 administration, olfactory and vomeronasal receptor neurones expressing the transgene were selectively eliminated from the olfactory epithelium (OE), and projections to the olfactory bulb (OB) were lost. The functional efficacy of cell ablation was demonstrated using a highly sensitive behavioural test to show that ablated mice had lost the olfactory ability to discriminate distinct odors and were consequently rendered anosmic. Targeted expression of Ntr to specific neuronal populations using conventional transgenes, as described here, or by “knock‐in” gene targeting using embryonic stem cells may be of significant value to address the functions of distinct neuronal populations in vivo. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 183–193, 2001
Combination of Jacobi–Davidson and conjugate gradients for the partial symmetric eigenproblem
Authors: Notay Y. 
Published: August 2002

AbstractTo compute the smallest eigenvalues and associated eigenvectors of a real symmetric matrix, we consider the Jacobi–Davidson method with inner preconditioned conjugate gradient iterations for the arising linear systems. We show that the coefficient matrix of these systems is indeed positive definite with the smallest eigenvalue bounded away from zero. We also establish a relation between the residual norm reduction in these inner linear systems and the convergence of the outer process towards the desired eigenpair. From a theoretical point of view, this allows to prove the optimality of the method, in the sense that solving the eigenproblem implies only a moderate overhead compared with solving a linear system. From a practical point of view, this allows to set up a stopping strategy for the inner iterations that minimizes this overhead by exiting precisely at the moment where further progress would be useless with respect to the convergence of the outer process. These results are numerically illustrated on some model example. Direct comparison with some other eigensolvers is also provided. Copyright © 2001 John Wiley & Sons, Ltd.
Inverse optimal design of cooling conditions for continuous quenching processes
Authors: Ruan Yimin 
Published: August 2002

AbstractThis paper presents an inverse design methodology to obtain a required yield strength with an optimal cooling condition for the continuous quenching of precipitation hardenable sheet alloys. The yield strength of a precipitation hardenable alloy can be obtained by allowing solute to enter into solid solution at a proper temperature and rapidly cooling the alloy to hold the solute in the solid solution. An aging process may be needed for the alloy to develop the final mechanical property. The objective of the design is to optimize the quenching process so that the required yield strength can be achieved. With the inverse design method, the required yield strength is specified and the sheet thermal profile at the exit of the quenching chamber can also be specified. The conjugate gradient method is used to optimize the cooling boundary condition during quenching. The adjoint system is developed to compute the gradient of the objective functional. An aluminium sheet quenching problem is presented to demonstrate the inverse design method. Copyright © 2001 John Wiley & Sons, Ltd.
A semi‐analytical locally transversal linearization method for non‐linear dynamical systems
Authors: Roy D. , Ramachandra L. S. 
Published: August 2002

AbstractAn numeric‐analytical, implicit and local linearization methodology, called the locally transversal linearization (LTL), is developed in the present paper for analyses and simulations of non‐linear oscillators. The LTL principle is based on deriving the locally linearized equations in such a way that the tangent space of the linearized equations transversally intersects that of the given non‐linear dynamical system at that particular point in the state space where the solution vector is sought. For purposes of numerical implementation, two different numerical schemes, namely LTL‐1 and LTL‐2 schemes, based on the LTL methodology are presented. Both LTL‐1 and LTL‐2 procedures finally reduce the given set of non‐linear ordinary differential equations (ODEs) to a set of transcendental algebraic equations valid over a short interval of time or over a short segment of the evolving trajectories as projected on the phase space. While in the LTL‐1 scheme the desired solution vector at a forward time point enters the linearized differential equations as an unknown parameter, in the LTL‐2 scheme a set of unknown residues enters the linearized system as parameters. A limited set of examples involving a few well‐known single‐degree‐of‐freedom (SDOF) non‐linear oscillators indicate that the LTL methodology is capable of accurately predicting many complicated non‐linear response patterns, including limit cycles, quasi‐periodic orbits and even strange attractors. Copyright © 2001 John Wiley & Sons, Ltd.
Genetic optimization of stiffened plates and shells
Authors: Marcelin J. L. 
Published: August 2002

AbstractThis work gives two examples of application of stochastic techniques for the optimization of stiffened plates or shells. The research strategy consists in substituting, for finite‐element calculations in the optimization process, an approximate response of a neural network, or an approximate response from the Ritz method. More precisely, the paper describes the use of a backpropagation neural network or the Ritz method in creating function approximations for use in computationally intensive design optimization based on genetic algorithms. Two examples of applications are presented; the first one deals with the optimization of stiffeners on a plate by varying their positions, while having well‐defined dimensions; the second example deals with the optimization of a thin shell subject to buckling. Copyright © 2001 John Wiley & Sons, Ltd.
Evolutionary thickness design with stiffness maximization and stress minimization criteria
Authors: Li Qing , Steven Grant P. , Xie Y. M. 
Published: August 2002

AbstractA shape or topology design with the stiffness maximized and the maximum stress minimized is usually of practical significance in structural optimization. This paper proposes a thickness based evolutionary procedure for such multicriteria design problems. To make the multicriteria optimization suit to more realistic structural situations, multiple maximum stress locations and multiple load cases are taken into account in this paper. To balance the stiffness and stress criteria, a weighting average scheme is adopted to identify the overall effects on the two components of design objective due to varying an element's thickness. Adopting the proposed optimization procedure, a design with maximized static stiffness and minimized peak stress is achieved by gradually shifting material from the under‐utilized regions onto the over‐utilized ones. The examples show the capabilities of the proposed method for solving multicriteria size and topology designs for both single and multiple load cases. Copyright © 2001 John Wiley & Sons, Ltd.
Efficient simulation of parameter‐dependent vehicle dynamics
Authors: Stämpfle M. , Hunt K. J. , Kalkkuhl J. 
Published: August 2002

AbstractThe vast majority of dynamical systems depend on system parameters. In this paper, we consider dynamical systems that arise from variation of two parameters within given parameter domains. Efficient adaptive methods for simultaneous simulation of such dynamical systems with parameter sets are presented. To enhance performance two key principles are introduced. Firstly, the principle of changing activity enables different states of activity for points of the parameter domain. And secondly, the principle of changing roles enables the usage of points of the parameter domain as mesh nodes, error grid points, and additional spare points in a flexible way. Various methods are tested on a model that describes the dynamics of a passenger vehicle. The model includes longitudinal and lateral motion as well as rotation around the vertical axis. As an example, the behaviour of the side slip angle is computed as a function of the vehicle mass and the height of the centre of gravity. The side slip angle is of special interest since it is an indicator for vehicle stability and thus passenger safety. Copyright © 2001 John Wiley & Sons, Ltd.
Singular perturbations for sensitivity analysis in symmetric bifurcation buckling
Authors: Godoy Luis A. , Banchio Enrique G. 
Published: August 2002

AbstractA direct procedure for the evaluation of imperfection‐sensitivity in bifurcation problems is presented. The problems arise in the context of the general theory of elastic stability (Koiter's theory) for discrete structural systems, in which the total potential energy is employed together with a stability criterion based on energy derivatives. The imperfection sensitivity of critical states, such as bifurcations and trifurcations, is usually represented as a plot of the critical load versus the amplitude ε of the imperfection considered. However, such plots have a singularity at the point with ε=0, so that a regular perturbation expansion of the solution is not possible. In this work, we describe a direct procedure to obtain the sensitivity of the critical load (eigenvalue of the bifurcation problem) and the sensitivity of the critical direction (eigenvector of the bifurcation problem) using singular perturbation analysis. The perturbation expansions are constructed as a power series in terms of the imperfection amplitude, in which the exponents and the coefficients are the unknowns of the problem. The solution of the exponents is obtained by means of trial and error using a least degenerate criterion, or by geometrical considerations. To compute the coefficients a detailed formulation is presented, which employs the conditions of equilibrium and stability at the critical state and their contracted forms. The formulation is applied to symmetric bifurcations, and the coefficients are solved up to third‐order terms in the expansion. The algorithmis illustrated by means of a simple example (a beam on an elastic foundation under axial load) for which the coefficients are computed and the imperfection‐sensitivity is plotted. Copyright © 2001 John Wiley & Sons, Ltd.
Fast exact linear and non‐linear structural reanalysis and the Sherman–Morrison–Woodbury formulas
Authors: Akgün Mehmet A. , Garcelon John H. , Haftka Raphael T. 
Published: August 2002

AbstractSeveral exact fast static structural reanalysis techniques, introduced by researchers mostly for truss structures and some for frames and plate structures, are reviewed. Most utilize the property that the solution of a system of linear equations can be updated inexpensively when the matrix is changed by a low‐rank increment. This paper shows that these methods are variants of the well‐known Sherman–Morrison and Woodbury (SMW) formulas for the update of the inverse of a matrix. In addition, the paper extends the low‐cost linear reanalysis in the spirit of the SMW formulas to some non‐linear reanalysis problems. For a linear reanalysis, the extension reduces to the SMW formulas. Copyright © 2001 John Wiley & Sons, Ltd.
Variational Delaunay approach to the generation of tetrahedral finite element meshes
Authors: Krysl Petr , Ortiz Michael 
Published: August 2002

AbstractWe describe an algorithm which generates tetrahedral decomposition of a general solid body, whose surface is given as a collection of triangular facets. The principal idea is to modify the constraints in such a way as to make them appear in an unconstrained triangulation of the vertex set à priori. The vertex set positions are randomized to guarantee existence of a unique triangulation which satisfies the Delaunay empty‐sphere property. (Algorithms for robust, parallelized construction of such triangulations are available.) In order to make the boundary of the solid appear as a collection of tetrahedral faces, we iterate two operations, edge flip and edge split with the insertion of additional vertex, until all of the boundary facets are present in the tetrahedral mesh. The outcome of the vertex insertion is another triangulation of the input surfaces, but one which is represented as a subset of the tetrahedral faces. To determine if a constraining facet is present in the unconstrained Delaunay triangulation of the current vertex set, we use the results of Rajan which re‐formulate Delaunay triangulation as a linear programming problem. Copyright © 2001 John Wiley & Sons, Ltd.
NMDA receptor mediates the response of trigeminovascular neurons of rats
Authors: Ahn Dong K. , Ju Jin S. , Park Jae S. 
Published: August 2002

AbstractThe present study was performed to evaluate the characteristics of excitory amino acid receptors in the synaptic transmission of trigeminovascular neurons in trigeminal subnucleus caudalis. Extracellular single‐unit recording of trigeminovascular neurons driven from dura or the superior sagittal sinus was made with a central barrel of seven‐barrel micropipette. DL‐2 amino‐5 phosphonovaleric acid, N‐methyl‐D‐aspartic acid (NMDA) receptor antagonist, produced a reversible inhibition of mechanical‐evoked responses in 10 of 12 examined trigeminovascular neurons. The maximal inhibition was 59 ± 5 % of the control. However, CNQX did not affect trigeminovascular neuronal responses. Substance P also facilitated NMDA‐evoked responses in 8 of 10 examined trigeminovascular neurons. The maximal facilitation was 153 ± 13 % of the control. These results imply that the NMDA receptor has a major role in the transmission of vascular headache (migraine) in trigeminovascular neurons and substance P also seems to be involved in maintenance migraine symptom.
Effect of brain‐derived neurotrophic factor in neural differentiation of mouse embryonic stem cells and neural precursor cells
Authors: Kang S.K. , Lee R.H. , Jung J.S. 
Published: August 2002

AbstractEmbryonic stem (ES) cells, which have pluripotency in differentiation, have been considered as an excellent source for cell replacement therapy of damaged tissues. Although neurotrophic factors induce neural differentiation in neural precursor cells, their actions in ES cells are not clear. This study was designated to examine the effect of brain‐derived neurotrophic factor (BDNF) on neural differentiation in mouse ES cells. Undifferentiated mouse ES cells were maintained at suspension culture in the presence of leukemia inhibitory factor (LIF), and neural precursor cells were isolated from the subventricular zone (SVZ) of the 2–3 day old mice brain. Oct‐4 was expressed in undifferentiated ES cells and neural precursor cells, of which expression was markedly decreased by induction of differentiation. RT‐PCR analysis showed that neural differentiation of ES cells induced expression of various neural markers, and that BDNF increased their expression. Western blot analysis demonstrated that BDNF induced expression of synaptophysin, a neuronal marker, and inhibited expression of glial fibrillary acidic protein, a glial marker. Undifferentiated ES cells expressed TrkA, TrkB and TrkC, of which expressions were increased during differentiation. Neural differentiation increased their expression, and BDNF further increased them. The treatment of BDNF during differentiation decreased expression of Notch1. These results indicated that BDNF induces neural differentiation and inhibits glial differentiation in ES cells as well as neuronal precursor cells.
Small dense‐cored vesicles are depleted of the classical synaptic vesicle membrane proteins synaptobrevin, synaptotagmin and Rab3
Authors: Strecker S. , Partoens P. , Slembrouck D. , Wang J‐M. , Courtoy P.J. , Nouwen E. , De Potter W.P. 
Published: August 2002

AbstractTo verify the association of vesicular docking/fusion proteins to small dense‐cored vesicles, we further purified a small dense‐cored vesicle population from rat vas deferens and searched for three components of the vesicular docking/fusion machinery known to act on target receptors at the plasma membrane: synaptobrevin (p18), synaptotagmin (p65) and the small GTPase Rab3. Further purification of small dense‐cored vesicles actually resulted in a depletion of these proteins, arguing against a direct participation of small dense‐cored vesicles in the exocytotic process. This finding points to a functional difference between small dense‐cored vesicles and either large dense‐cored or small clear synaptic vesicles.
Strategies associated with altered segment parameters during voluntary gait modifications
Authors: Reid M.J. , Prentice S.D. 
Published: August 2002

AbstractThe coordination of movement results from complex interactions between neural and mechanical systems. To investigate the influence of limb mechanics on the control strategies used during gait modifications, participants were instructed to walk and step over various obstacles (2,10, & 30cm) with and without an external mass (4.5kg) attached around the centre of mass of each leg segment. Overall, with the attached mass there was an increase in the amount of pull‐off energy applied at the hip, while the contribution of the knee to limb flexion decreased particularly for the higher obstacles. It was further found that knee action during weighted conditions served more to slow the backward motion of the leg following toe off than to flex the knee. The modifications employed to accomodate the change in limb dynamics illustrate both the flexibility of the locomotor control system and its sensitivity to the mechanical properties of the limb.
Neuroprotective effect of nicardipine on cadmium‐induced Purkinje cell death in rat cerebellum
Authors: Bağirici Faruk , Genç Hayri , Tan Faruk , Demir Şerif 
Published: August 2002

AbstractThe present study was designed to investigate the effects of nicardipine on cadmium‐induced Purkinje cell loss in cerebellum of rats. Animals were divided into three groups as control, cadmium and cadmium + nicardipine groups. Saline, cadmium sulphate (0,0021 mg/kg) and cadmium sulphate (0,0021 mg/kg) + nicardipine (1 mg/kg) were intracortically administered respectively. All rats were observed for one week, but only the rats in the third group were injected nicardipine (10 mg/kg/day, i.p.) during this period. One week later, all rats were perfused intracardially. Series of frontal sections from cerebella were stained with Thionin staining. Purkinje cells were counted under ×400 magnification via a light microscopeCadmium administration caused 25–35 % decrease in Purkinje cell density in Crus I, Crus II and Lobulus Simplex areas of cerebellum in cadmium group (p<0.05). The Purkinje cell density was 16–23 % less in nicardipine‐treated group than control and cells were partially protected from toxic effects of cadmium significantly (p<0.05).These results suggest that cadmium has neurotoxic effects on Purkinje cells in cerebellum and nicardipine may protect neurons from cadmium‐induced toxicity (p<0.05).
Implicit kinetic schemes for scalar conservation laws
Authors: Botchorishvili Ramaz 
Published: August 2002

AbstractBased on kinetic formulation for scalar conservation laws, we present implicit kinetic schemes. For time stepping these schemes require resolution of linear systems of algebraic equations. The scheme is conservative at steady states. We prove that if time marching procedure converges to some steady state solution, then the implicit kinetic scheme converges to some entropy steady state solution. We give sufficient condition of the convergence of time marching procedure. For scalar conservation laws with a stiff source term we construct a stiff numerical scheme with discontinuous artificial viscosity coefficients that ensure the scheme to be equilibrium conserving. We couple the developed implicit approach with the stiff space discretization, thus providing improved stability and equilibrium conservation property in the resulting scheme. Numerical results demonstrate high computational capabilities (stability for large CFL numbers, fast convergence, accuracy) of the developed implicit approach. © 2002 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 18: 26–43, 2002
Marine resources from an urban Moche (470–600 ad) area in the ‘Huacas del Sol y de la Luna’ archaeological complex (Trujillo, Peru)
Authors: Roselló E. , Vásquez V. , Morales A. , Rosales T. 
Published: August 2002

AbstractAn analysis of the marine animal remains retrieved in a sector of Huacas de Moche archaeological complex is presented. The area,14C‐dated between 470 and 600 ad (Moche IV/V), includes a poorly diversified fauna with two dominating species (donax clam and hake) despite the large number of secondary taxa (71). Such faunal spectrum corresponds to a secondary type of cropping strategy, likely to go through some kind of cultural filter (market), thus indirectly certifying the social complexity of Moche urban centres in general and the centralized and redistributive nature of Moche economy in particular. From an environmental standpoint most of the taxa indicate ‘normal’ (i.e. non‐El Niño–Southern Oscillation (ENSO)) conditions and their abundance and ecological affinities correspond to what one could expect to find at present on the shores of the Moche Valley. The fish assemblage, moreover, suggests the existence of a low status population whereas complementary data indicate that a few of the taxa might not have had exclusively dietary connotations. Copyright © 2001 John Wiley & Sons, Ltd.
Polymer bound glutamic acid salicylaldehyde Schiff‐base complex ­catalyst for oxidation of olefins with ­dioxygen
Authors: Wang Rong‐Min , Hao Cheng‐Jun , He Yu‐Feng , Wang Yun‐Pu , Xia Chun‐Gu 
Published: August 2002

AbstractThe polymer bound Schiff‐base ligand (PS‐SalGlu) has been prepared from polystyrene bound salicylaldehyde and glutamic acid, and its complex (PS‐SalGlu‐Co) has also been synthesized. The polymer ligand and its complex were characterized by infrared spectroscopy, small area X‐ray photoelectron spectroscopy, and inductively coupled plasma‐atomic emission spectro (ICP‐AFS). In the presence of the complex, cyclohexene can be effectively oxidized by molecular oxygen without reductant. The long‐chain linear aliphatic olefins, such as 1‐octene, 1‐decene, 1‐dodecene and 1‐tetradecene, can be directly oxidized by molecular oxygen catalyzed by PS‐SalGlu‐Co, which affords the 1,2‐epoxy alkane. Copyright © 2001 John Wiley & Sons, Ltd.