bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nigral degeneration and striatal dopaminergic dysfunction in idiopathic and parkin‐linked Parkinson's disease
Authors: Hu Michele T.M. , Scherfler Christoph , Khan Naheed L. , Hajnal Jo V. , Lees Andrew J. , Quinn Niall , Wood Nicholas W. , Brooks David J. 
Published: October 2005

AbstractWe have used MR segmented inversion recovery ratio imaging (SIRRIM) of the substantia nigra pars compacta to detect and correlate nigral signal change in idiopathic Parkinson's disease (PD) and parkin patients with striatal 18F‐dopa uptake. Nine PD patients, nine parkin patients, and eight control subjects were studied with a combination of MR inversion recovery sequences sensitive to nigral cell loss. Blinded independent observer rating and quantified nigral signal analysis were performed on all subjects. Striatal regions of interest were defined on T1‐weighted MRI coregistered to 18F‐dopa positron emission tomography. On blinded observer rating of the SIRRIM dorsal and ventral nigral images, 25% (2/8) of control subjects, 44% (4/9) of PD patients, and 67% (6/9) of parkin patients were classified as abnormal. Quantified total nigral signal intensities were reduced to a greater extent in the parkin compared to PD patients. There was a greater predilection for signal reduction in the ventral nigral slice of the PD compared to the parkin patient group, who showed a more uniform involvement. All PD and parkin patients were discriminated from controls on the basis of caudate and putamen 18F‐dopa Ki reductions. Our results suggest that MR segmented inversion recovery ratio imaging shows poor sensitivity for discriminating parkin and idiopathic PD patients from normal controls. Where nigral signal abnormalities were seen, parkin patients manifested generalized nigral cell loss with widespread striatal dopamine terminal dysfunction compared with the lateral nigral targeting seen in PD and selective loss of putamen 18F‐dopa uptake. © 2005 Movement Disorder Society
Pergolide versus levodopa monotherapy in early Parkinson's disease patients: The PELMOPET study
Authors: Oertel Wolfgang H. , Wolters Erik , Sampaio Cristina , Gimenez‐Roldan Santiago , Bergamasco Bruno , Dujardin Max , Grosset Donald G. , Arnold Guy , Leenders Klaus L. , Hundemer Hans‐Peter , Lledó Alberto , Wood Andrew , Frewer Paul , Schwarz Johannes 
Published: October 2005

AbstractDopamine agonists are used as initial treatment in patients with Parkinson's disease (PD) to reduce incidence and severity of motor complications. This paradigm is based on long‐term studies, allowing “rescue” therapy with levodopa. The present strict monotherapy study (PELMOPET, the acronym for the pergolide‐versus‐L‐dopa‐monotherapy‐and‐positron‐emission‐tomography trial) evaluated the efficacy and safety of pergolide versus levodopa without levodopa “rescue” medication. This multicenter, double‐blind, randomized, 3‐year trial compared pergolide monotherapy (n = 148) with levodopa monotherapy (n = 146) in dopamine‐naive patients with early PD (Hoehn and Yahr stage 1–2.5). Primary efficacy measures were clinical efficacy, severity and time to onset of motor complications, and disease progression. During the 3 years, severity of motor complications was significantly lower and time to onset of dyskinesia was significantly delayed in the group receiving pergolide (3.23 mg/day) compared with those receiving levodopa (504 mg/day). However, time to onset of motor complications was not longer in patients receiving pergolide after 3 years. Symptomatic relief (assessed by Unified Parkinson's Disease Rating Scale [UPDRS], UPDRS II, and III, Clinical Global Impressions [CGI] severity, and CGI and Patient Global Impressions [PGI] improvement) was significantly greater in patients receiving levodopa. Adverse events led to discontinuation of therapy in 17.6% of pergolide patients and 9.6% of levodopa patients. This is the first study comparing strict monotherapy with a dopamine agonist versus levodopa in previously untreated early PD. In principle, both levodopa and a dopamine agonist such as pergolide seem to be suitable options as initial PD therapy. The choice remains with the treating physician based on the different efficacy and adverse event profiles. © 2005 Movement Disorder Society
Minimal‐energy splines: I. Plane curves with angle constraints
Authors: Jou Emery D. , Han Weimin 
Published: October 2005

AbstractThis is the first in a series of papers on minimal‐energy splines. The paper is devoted to plane minimal‐energy splines with angle constraints. We first consider minimal‐energy spline segments, then general minimal‐energy spline curves. We formulate problems for minimal‐energy spline segments and curves, prove the existence of solutions, justify the Lagrange multiplier rules, and obtain some nice properties (e.g., the infinite smoothness). Finally, we report our computational experience on minimal‐energy splines.
Taylor expansions for distributions
Authors: Estrada R. , Kanwal R. P. 
Published: October 2005

AbstractWe present the Taylor asymptotic expansion of a perturbed distribution of the form
equation image
is a smooth function defined in ℝn. First we present the one‐dimensional theory to illustrate the underlying concepts and then we discuss the multi‐dimensional case. We find that various known results follow as special limits of our results.
Parameter‐dependent operator equations of the Riccati type with application to transport theory
Authors: Kuiper Hendrik J. , Mazumdar Tapas 
Published: October 2005

AbstractWe obtain an existence result for global solutions to initial‐value problems for Riccati equations of the form R′(t) + TR(t) + R(t)T = Tρ A(t)T1−ρ + Tρ B(t)T1−ρ R(t) + R(t)TρC(t) T1−ρ + R(t)TρD(t)T1−ρ R(t), R(0)=R0, where 0 ⩽ ρ ⩽ 1 and where the functions R and A through D take on values in the cone of non‐negative bounded linear operators on L1 (0, W; μ). T is an unbounded multiplication operator. This problem is of particular interest in case ρ = 1 since it arisess in the theories of particle transport and radiative transfer in a slab. However, in this case there are some serious difficulties associated with this equation, which lead us to define a solution for the case ρ = 1 as the limit of solutions for the cases 0 < ρ < 1.
Weak solutions of the Vlasov–Poisson initial boundary value problem
Authors: Alexandre Radjesvarane 
Published: October 2005

AbstractThis paper deals with existence results for a Vlasov‐Poisson system, equipped with an absorbing‐type law for the Vlasov equation and a Dirichlet‐type boundary condition for the Poisson part. Using the ideas of Lions and Perthame [21], we prove the existence of a weak solution having good Lp estimates for moment and electric field, by a good control on the higher moments of the initial data. As an application, we establish a homogenization result in the Hilbertian framework for this type of problem in non‐homogeneous media, following the work by Alexandre and Hamdache [2] for general kinetic equations, and Cioranescu and Mural [11] for the Laplace problem.
Classical solutions of two‐dimensional stokes problems on non‐smooth domains. Part 2: Collocation method for the radon equation
Authors: Lubuma Jean Mbaro‐Saman 
Published: October 2005

AbstractThe non‐uniquely solvable Radon boundary integral equation for the two‐dimensional Stokes‐Dirichlet problem on a non‐smooth domain is transformed into a well posed one by a suitable compact perturbation of the velocity double‐layer potential operator. The solution to the modified equation is decomposed into a regular part and a finite linear combination of intrinsic singular functions whose coefficients are computed from explicit formulae. Using these formulae, the classical collocation method, defined by continuous piecewise linear vector‐valued basis functions, which converges slowly because of the lack of regularity of the solution, is improved into a collocation dual singular function method with optimal rates of convergence for the solution and for the coefficients of singularities.
On the averaging method for rod equations with quadratic non‐linearity
Authors: Buitelaar R. P. 
Published: October 2005

AbstractThe averaging method is used to approximate solutions of systems of linearly coupled, (quadratic) non‐linear dispersive wave equations, which describe extensional–torsional dynamics of a rod. Existence and uniqueness results are established. Error estimates confirm the asymptotic validity of the approximation method on a long time‐scale. The linear couplings between the equations imply that resonance can occur inside a single mode of the solution, but energy can also be transferred to other modes.
Periodic optimal control for parabolic Volterra‐Lotka type equations
Authors: He Feiyue , Leung Anthony , Stojanovic Srdjan 
Published: October 2005

AbstractThis paper considers the optimal harvesting control of a biological species, whose growth is governed by the parabolic diffusive Volterra‐Lotka equation. We prove that such equation with L∞ periodic coefficients has an unique positive periodic solution. We show the existence and uniqueness of an optimal control, and under certain conditions, we characterize the optimal control in terms of a parabolic optimality system. A monotone sequence which converges to the optimal control is constructed.
Similarity solutions of dispersive long‐wave equations in two space dimensions
Authors: Sen‐Yue Lou 
Published: October 2005

AbstractIn this paper, both the direct method and the non‐classical Lie approach are applied to reduce the (2 + 1)‐dimensional dispersive long wave equations. Nine types of two‐dimensional PDE reductions and 13 types of ODE reductions are given. All the known reductions obtained by the classical Lie approach are reobtained as some special cases. Similar to the (1 + 1)‐dimensional case, some types of reductions with essential and logarithmic singular characteristic manifolds are allowed although the model is integrable.
Quaternion non‐linear filter for estimation of rotating body attitude
Authors: Aramanovitch L. I. 
Published: October 2005

AbstractA problem of optimal estimation of a rotating vehicle's attitude with both differential equations of motion and observations of stars by onboard equipment is considered. The problem is formulated like a determinate non‐linear Kalman filter problem in quaternion terms. An exact analytical solution of the problem is also found in quaternion terms. Various types of solutions in accordance with a mutual arrangement of observed stars are presented. An example of only one observed star is demonstrated to support the method. The method is also suited for geodetic applications, e.g. geodetic positioning and navigation systems.
On the roots of the orthogonal polynomials and residual polynomials associated with a conjugate gradient method
Authors: Manteuffel Thomas A. , Otto James S. 
Published: October 2005

AbstractIn this paper we explore two sets of polynomials, the orthogonal polynomials and the residual polynomials, associated with a preconditioned conjugate gradient iteration for the solution of the linear system Ax = b. In the context of preconditioning by the matrix C, we show that the roots of the orthogonal polynomials, also known as generalized Ritz values, are the eigenvalues of an orthogonal section of the matrix C A while the roots of the residual polynomials, also known as pseudo‐Ritz values (or roots of kernel polynomials), are the reciprocals of the eigenvalues of an orthogonal section of the matrix (C A)−1. When C A is selfadjoint positive definite, this distinction is minimal, but for the indefinite or nonselfadjoint case this distinction becomes important. We use these two sets of roots to form possibly nonconvex regions in the complex plane that describe the spectrum of C A.
Stability of block LU factorization
Authors: Demmel James W. , Higham Nicholas J. , Schreiber Robert S. 
Published: October 2005

AbstractMany of the currently popular ‘block algorithms’ are scalar algorithms in which the operations have been grouped and reordered into matrix operations. One genuine block algorithm in practical use is block LU factorization, and this has recently been shown by Demmel and Higham to be unstable in general. It is shown here that block LU factorization is stable if A is block diagonally dominant by columns. Moreover, for a general matrix the level of instability in block LU factorization can be bounded in terms of the condition number K(A) and the growth factor for Gaussian elimination without pivoting. A consequence is that block LU factorization is stable for a matrix A that is symmetric positive definite or point diagonally dominant by rows or columns as long as A is well‐conditioned.
The geometric stiffness of thick shell triangular finite elements for large rotations
Authors: Levy R. , Gal E. 
Published: October 2005

AbstractThis paper is concerned with the development of the geometric stiffness matrix of thick shell finite elements for geometrically nonlinear analysis of the Newton type. A linear shell element that is comprised of the constant stress triangular membrane element and the triangular discrete Kirchhoff Mindlin theory (DKMT) plate element is ‘upgraded’ to become a geometrically nonlinear thick shell finite element. Perturbation methods are used to derive the geometric stiffness matrix from the gradient, in global coordinates, of the nodal force vector when stresses are kept fixed. The present approach follows earlier works associated with trusses, space frames and thin shells. It has the advantage of explicitness and clear physical insight. A special procedure, tailored to triangular elements is used to isolate pure rotations to enable stress recovery via linear elastic constitutive relations. Several examples are solved. The results compare well with those available in the literature. Copyright © 2005 John Wiley & Sons, Ltd.
Augmented canonical forms and factorization of graphs
Authors: Kaveh A. , Sayarinejad M. A. 
Published: October 2005

AbstractThe main aim of this paper is to generalize the previously developed canonical forms by different types of alterations and/or augmentations. These forms provide suitable tools for the decomposition of the matrices of special patterns and lead to efficient aproaches for calculating their eigenvalues.Methods were developed for factorization of symmetric graphs into smaller subgraphs using decompostion and healings (Commun. Numer. Meth. Engng 2003; 19:125–136, 2004; 20:133–146, 2004; 20:889–910; Comput. Struct. 2004; 18:2229–2240). Further factorization was possible only when further symmetries were available. The main drawback was associated with non‐decomposiblity of some of the factors in early stages of decomposition, and in particular healing which often destroyed the symmetry. In this paper, the mathematical concepts related to certain symmetric and unsymmetric graphs are developed, making refined factorization of the graphs feasible. Examples are included to show the simplicity of the operations being involved. Copyright © 2005 John Wiley & Sons, Ltd.
Numerical simulation of fluid flow and temperature field in keyhole double‐sided arc welding process on stainless steel
Authors: Honggang Dong , Hongming Gao , Lin Wu 
Published: October 2005

AbstractDouble‐sided arc welding process powered by a single supply is a type of novel high‐production process. In comparison with the conventional single‐sided arc welding, this process has remarkable advantages in enhancing penetration, minimizing distortion and improving welding production. In this paper, a three‐dimensional steady numerical model is developed for the heat transfer and fluid flow in plasma arc (PA)–gas tungsten arc (GTA) double‐sided keyhole welding process. The model considers the surface tension gradient, electromagnetic force and buoyancy force. A CCD camera is used to observe the size and shape of the keyhole and weld pool. The acquired images are analysed through image processing to obtain the surface diameters of the keyhole on the two sides. A double‐V‐shaped keyhole geometry is then proposed and its characteristic parameters are derived from the images and cross‐section of weld bead. In the numerical model, the keyhole cavum within the weld pool is treated as a whole quality, whose temperature is fixed at the boiling point of the workpiece material. The heat exchange between the keyhole and weld pool is treated as an interior boundary of the workpiece. Based on the numerical model, the distributions of the fluid flow and temperature field are calculated. A comparison of cross‐section of the weld bead with the experimental result shows that the numerical model's accuracy is reasonable. Copyright © 2005 John Wiley & Sons, Ltd.
Space‐time finite elements incorporating characteristics for the burgers' equation
Authors: Varoḡlu Erol , Liam Finn W. D. 
Published: October 2005

AbstractA new finite element method is presented for the numerical solution of the Burgers' equation. The method is based on a weighted residual formulation in which the method of characteristics is incorporated by employing isoparametric space–time elements with the sides joining the nodes at subsequent time levels oriented along the characteristic lines of the hyperbolic partial differential equation associated with the Burgers' equation.This method is capable of solving the Burgers' equation accurately for values of viscosity ranging from very small to large. The utility and accuracy of the method are demonstrated by a number of examples and a comparison of the numerical results with the exact solution is presented in one case.
Automated adaptive two‐dimensional system for the hp‐version of the finite element method
Authors: Georges M. K. , Shephard M. S. 
Published: October 2005

AbstractThis paper presents an automated, adaptive finite element modelling system based on the hp‐version of the finite element method. Error estimation and correction indication procedures with an automatic mesh generator and a p‐version analysis code are combined to provide a computationally efficient modelling environment. Error prediction techniques are employed to find the best combination of finite element discretization, h‐, and overall polynomial order, p‐, needed to achieve the prescribed level of accuracy. The automated adaptive modelling results demonstrate the capability of the modelling system of predicting discretizations to perform a p‐version finite element analysis to achieve prescribed levels of accuracy in the most efficient manner.
Synthesis of a thermoresponsive shell‐crosslinked 3‐layer onion‐like polymer particle with a hyperbranched polyglycerol core
Authors: Wan Decheng , Fu Qiang , Huang Junlian 
Published: October 2005

AbstractA novel thermoresponsive shell crosslinked three‐layer onion‐like polymer particles were prepared using hyperbranched polyglycerol (PG) as parents compound, the periphery hydroxyl groups of PG were transformed into trithiocarbonates (SC(S)S) first; then, it was used as chain transfer agent to prepare star‐like block copolymer of N‐isopropyl acrylamide (NIPA) and N,N‐dimethylaminoethyl acrylate (DMA) in sequence via reversible addition fragmentation chain transfer (RAFT) process. Thus, a three‐layer polymer, PG[SC(S)S(DMA)b(NIPA)]n, was obtained. The middle layer of poly(DMA) was then crosslinked with 1,8‐diiodoctane, and the resulting onion‐like three‐layer polymer showed a lower critical solution temperature (LCST) in water because of the outer layer of poly(NIPA). The LCST value only slightly depended on the crosslinking degree. Finally, the SC(S)S were transformed into thiols by sequential treating with sodium borohydride and formic acid; thus, the core molecule was chemically detached from the crosslinked shell and a novel shell crosslinked polymer particle was obtained. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5652–5660, 2005
Validation of the Distress Thermometer with bone marrow transplant patients
Authors: Ransom Sean , Jacobsen Paul B. , Booth‐Jones Margaret 
Published: October 2005

AbstractThe Distress Thermometer (DT) is a one‐item screening measure of psychological distress in cancer patients. This study examines the operating characteristics of the DT in patients about to undergo bone marrow transplant (BMT). Patients (N=491) completed the DT, the Center for Epidemiological Studies‐Depression Scale (CES‐D), the State‐Trait Anxiety Inventory‐State Version (STAI‐S), the ECOG Performance Status Scale, and the Patient Problem List. DT scores were related to higher depression, higher anxiety, and poorer performance status. Receiver operating characteristic (ROC) curve analyses of DT scores yielded area under the curve estimates of 0.75 when compared to the CES‐D cutoff score of 16, suggesting the DT has acceptable overall accuracy. The DT cutoff score of 4 had the greatest sensitivity and specificity when compared to the CES‐D cutoff score. Patients above this cutoff score reported worse ECOG scores and more practical, family, emotional, and physical problems (all p's⩽0.05) than those below the cutoff. The findings suggest the DT is a useful tool for screening for distress in BMT patients. The optimal DT cutoff score of 4 found here was identical to that found in another study using different criteria. This cutoff score also identified patients with problems likely to reflect psychological distress. Copyright © 2005 John Wiley & Sons, Ltd.
Non‐centrosymmetric molybdates CsLiMoO4 and CsLiMoO4·⅓H2O: crystal growth, polymorphism, efficient Stokes and anti‐Stokes generation and cascaded self‐frequency [χ(3)(SRS) → χ(2)(SFM)] conversion effects
Authors: Becker P. , Bohatý L. , Fröhlich R. , Eichler H. J. , Ueda K. , Takaichi K. , Hanuza J. , Maczka M. , Rhee H. , Kaminskii A. A. 
Published: October 2005

AbstractThe cover picture of this issue of physica status solidi (a) is a structure plot of the unit cells of CsLiMoO4 (left) and CsLiMoO4 · 1/3H2O (right). [MoO4] and [LiO4] groups are represented by green and yellow polyhedra, respectively, Cs is given by orange spheres. Smaller violet spheres represent possible positions of oxygen of water molecules in CsLiMoO4 · 1/3H2O, the occupation factor of these positions being 1/3.
A fast reflectance anisotropy spectrometer for in situ growth monitoring
Authors: Kaspari Christian , Pristovsek Markus , Richter Wolfgang 
Published: October 2005

AbstractWe report on an optical multichannel RAS (Reflectance Anisotropy Spectroscopy) setup capable of measuring at multiple photon energies simultaneously in the spectral range between 1.4 and 5.0 eV at a temporal resolution of up to 30 ms. The setup is specifically designed for time‐resolved studies of surface processes (e.g. epitaxial growth). Its accuracy was evaluated on static surfaces by comparison with RAS spectra acquired using a conventional scanning RAS setup. The performance was demonstrated by studying 2D island growth oscillations during GaAs epitaxy with TMGa and AsH3 or tBAs in metal‐organic vapour phase epitaxy (MOVPE). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)