bluuebunny/crossref_metadata_2025_split huggingface dataset:
Semilinear wave equation with time dependent potential
Authors: Visciglia Nicola 
Published: November 2004

AbstractWe consider the following semilinear wave equation:
equation image
for (t,x) ∈ ℝt × ℝ. We prove that if the potential V(t,x) is a measurable function that satisfies the following decay assumption:
∣V(t,x)∣⩽C(1+t)(1+∣x∣) for a.e. (t,x) ∈ ℝt × ℝ
where C, σ0>0 are real constants, then for any real number λ that satisfies ${1+\sqrt{2}&#60; \lambda &#60;3}$ there exists a real number ρ(f,g,λ)>0 such that the equation has a global solution provided that 0<ρ⩽ρ(f,g,λ). Copyright © 2004 John Wiley & Sons, Ltd.
Floating table isotropic projection (FLIPR) acquisition: A time‐resolved 3D method for extended field‐of‐view MRI during continuous table motion
Authors: Fain Sean B. , Browning Fred J. , Polzin Jason A. , Du Jiang , Zhou Yong , Block Walter F. , Grist Thomas M. , Mistretta Charles A. 
Published: November 2004

AbstractIn this work, 3D vastly undersampled isotropic projection (VIPR) acquisition is used simultaneously with continuous table motion to extend the superior/inferior (S/I) FOV for MR angiograms. The new technique is termed floating table isotropic PR (FLIPR). The use of 3D PR in conjunction with table motion obviates the need to locate and prescribe imaging volumes containing the major blood vessels over the large superior–inferior (S/I) ranges encountered in whole‐body imaging. In addition, the FLIPR technique provides extended anterior–posterior (A/P) abdominal coverage, isotropic spatial resolution, and temporal resolution. In volunteer studies, FLIPR MR angiograms with 1.6‐mm isotropic spatial resolution that approached whole body in extent were acquired in less than 2 min. Magn Reson Med 52:1093–1102, 2004. © 2004 Wiley‐Liss, Inc.
Perfusion assessment with bolus differentiation: A technique applicable to hyperpolarized tracers
Authors: Johansson E. , Olsson L.E. , Månsson S. , Petersson J.S. , Golman K. , Ståhlberg F. , Wirestam R. 
Published: November 2004

AbstractA new technique for assessing tissue blood flow using hyperpolarized tracers, based on the fact that the magnetization of a hyperpolarized substance can be destroyed permanently, is described. Assessments of blood flow with this technique are inherently insensitive to arterial delay and dispersion, and allow for quantification of the transit time and dispersion in the arteries that supply the investigated tissue. Renal cortical blood flow was studied in six rabbits using a 13C‐labeled compound (2‐hydroxyethylacrylate) that was polarized by the parahydrogen‐induced polarization (PHIP) technique. The renal cortical blood flow was estimated to be 5.7/5.4 ± 1.6/1.3 ml/min per milliliter of tissue (mean ± SD, right/left kidney), and the mean transit time and dispersion in the renal arteries were determined to be 1.47/1.42 ± 0.07/0.07 s and 1.78/1.93 ± 0.40/0.42 s2, respectively. Magn Reson Med 52:1043–1051, 2004. © 2004 Wiley‐Liss, Inc.
Quantification of the 31P metabolite concentration in human skeletal muscle from RARE image intensity
Authors: Greenman Robert L. 
Published: November 2004

AbstractA method is described for quantifying the cellular phosphorus‐31 (31P) concentration in human skeletal muscle based on RARE (rapid acquisition with relaxation enhancement) image intensities. The 31P concentrations were calculated using relaxation rates, RF coil spatial characteristics, and RARE signal intensities from foot muscle and an external 31P standard. 31P RARE and 1H T2‐weighted images of the foot muscles in 11 normal subjects were acquired at 3.0 T using a double‐tuned (31P/1H) birdcage coil. 31P PRESS (point‐resolved spectroscopy) spectra were acquired to verify the measurable 31P concentrations in a multiecho acquisition. The mean measured concentration was 26.4 ± 3.1 mM (mean ± SD) from RARE signal intensities averaged over the entire imaged foot anatomy and 27.6 ± 4.1 mM for a 3 × 3 pixel region‐of‐interest measurement. The 31P RARE image acquisition time was 4 min with a 0.55 cm3 voxel size. These results demonstrate that the 31P concentration can be accurately measured noninvasively in human muscle from RARE images acquired in short scan times with relatively high spatial resolution. Magn Reson Med 52:1036–1042, 2004. © 2004 Wiley‐Liss, Inc.
Spatial correlations of laminar BOLD and CBV responses to rat whisker stimulation with neuronal activity localized by Fos expression
Authors: Lu Hanbing , Patel Sachin , Luo Feng , Li Shi‐Jiang , Hillard Cecilia J. , Ward B. Douglas , Hyde James S. 
Published: November 2004

AbstractThe spatial relationship between a measured fMRI signal and its underlying neuronal activity remains unclear. One obstacle is the localization of neuronal activity; another is the spatial resolution of fMRI. In the present study, high‐resolution BOLD and CBV fMRI experiments (voxel size: 156 × 156 × 2000 μm3) were conducted in the rat whisker barrel cortex at 3 T; neuronal activity across cortical layers was mapped using the Fos expression technique. Results show that BOLD response is weighted by blood volume and that pixels with high BOLD response can be located at the cortical surface or in deep layers, depending on local vasculature. In contrast to BOLD response, the pixels with high CBV response were consistently clustered in the deep cortical layers. Percentage‐CBV change in cortical layers IV–V was 7.3 ± 1.5%, which was significantly higher than in layers I–III (4.1 ± 0.9%) and VI (4.3 ± 0.7%) (mean ± SEM). The laminar distribution of CBV response correlates well with neuronal activity localized by Fos expression. We conclude that neuronal activity can be inferred from CBV fMRI data with high spatial accuracy. The data indicate that both intracolumn functional connectivity and neurovascular coupling can be studied using CBV fMRI. Magn Reson Med 52:1060–1068, 2004. © 2004 Wiley‐Liss, Inc.
System reliability based on diffusion models for fatigue crack growth
Authors: Ebrahimi Nader 
Published: November 2004

AbstractDiffusion processes are commonly used to describe the dynamics of complex systems arising in a wide range of application fields. In this paper we propose, on the basis of diffusion processes, two models concerned with the stochastic behavior of fatigue cracks in a system. They are then used to get the distribution of the failure time, the first time the crack size of at least one of the cracks exceeds a given value. Several properties of our proposed models are presented, and the unknown parameters are estimated by the method of maximum likelihood. From these an estimate of failure time distribution is obtained. In this part, contrary to common practice, we do not assume availability of failure data. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2005
Relaxation induced by ferritin: a better understanding for an improved MRI iron quantification
Authors: Gossuin Yves , Muller Robert N. , Gillis Pierre 
Published: November 2004

AbstractFerritin, the iron storing protein, is known to darken T2‐weighted MRI. This darkening can be used to non‐invasively measure iron content. However, ferritin's behavior is not the same in tissue as in solution, a discrepancy that remains unexplained by the recently developed theory matching the NMR properties of ferritin solutions. A better understanding of the relaxation induced by ferritin in tissue could help for the development of new MRI protocols of iron quantification. In this short review, the main relaxation properties of ferritin in solution and in tissue are presented together with a discussion of the possible reasons for the faster transverse relaxation observed in tissues. Copyright © 2004 John Wiley & Sons, Ltd.
High‐resolution MR imaging of mouse brain microvasculature using the relaxation rate shift index Q
Authors: Wu Ed X. , Tang Haiying , Jensen Jens H. 
Published: November 2004

AbstractMagnetic resonance imaging (MRI) is a powerful method for in vivo quantification of tissue properties. It has been previously proposed that the index Q ≡ δR2/(δR)2/3, where ΔR2 and δR are the spin echo and gradient echo relaxation rate shifts caused by the injection of an intravascular contrast agent, may be useful for characterizing microvasculature. In particular, Q is expected to correlate well with the density of microvessels. This study presents high‐resolution in vivo Q‐maps of normal mouse brain obtained with a superparamagnetic iron oxide contrast agent at a field of level of 9.4 T. Normative Q values are derived for several regions of interest and significant interregional variations are observed. Microvessel densities estimated from the Q‐maps are found to be in reasonable accord with histologically determined values. A possible application of Q‐maps is the assessment of angiogenic activity in tumors. Copyright © 2004 John Wiley & Sons, Ltd.
Iron oxide MR contrast agents for molecular and cellular imaging
Authors: Bulte Jeff W. M. , Kraitchman Dara L. 
Published: November 2004

AbstractMolecular and cellular MR imaging is a rapidly growing field that aims to visualize targeted macromolecules or cells in living organisms. In order to provide a different signal intensity of the target, gadolinium‐based MR contrast agents can be employed although they suffer from an inherent high threshold of detectability. Superparamagnetic iron oxide (SPIO) particles can be detected at micromolar concentrations of iron, and offer sufficient sensitivity for T2(*)‐weighted imaging. Over the past two decades, biocompatible particles have been linked to specific ligands for molecular imaging. However, due to their relatively large size and clearance by the reticuloendothelial system (RES), widespread biomedical molecular applications have yet to be implemented and few studies have been reproduced between different laboratories. SPIO‐based cellular imaging, on the other hand, has now become an established technique to label and detect the cells of interest. Imaging of macrophage activity was the initial and still is the most significant application, in particular for tumor staging of the liver and lymph nodes, with several products either approved or in clinical trials. The ability to now also label non‐phagocytic cells in culture using derivatized particles, followed by transplantation or transfusion in living organisms, has led to an active research interest to monitor the cellular biodistribution in vivo including cell migration and trafficking. While most of these studies to date have been mere of the ‘proof‐of‐principle’ type, further exploitation of this technique will be aimed at obtaining a deeper insight into the dynamics of in vivo cell biology, including lymphocyte trafficking, and at monitoring therapies that are based on the use of stem cells and progenitors. Copyright © 2004 John Wiley & Sons, Ltd.
Adaptivity for finite volume on unstructured triangular meshes: a study of thermal injury in teeth
Authors: Martins Marcio Arêdes , Oliveira Leandro Soares , Valle Ramón Molina 
Published: November 2004

AbstractThis paper presents a numerical study of thermal injury in teeth, caused both by convective heating, due to drinking of hot beverage and mastication of foods, and by laser irradiation in dental treatment. The numerical study employs an adaptive finite volume method on unstructured triangular meshes to solve the governing equations. An adaptive time stepping methodology was also used in order to control the solution error. Adaptive methodologies are adequate to solve such problems since steep gradients will develop at specific locations in the domain of study. The convective heating results were compared to experimental data available in the literature. Laser treatment results are in agreement to the temperature increasing observed in literature. The simulation results demonstrate that both the error estimate and adaptive methodology herein proposed are suitable and reliable for the controlled solution of parabolic problems. Copyright © 2004 John Wiley & Sons, Ltd.
Investigation for aneuploidy of chromosomes 7, 9, 10, 17 and p53 gene deletions between low and high grade glial tumors using interphase FISH technique
Authors: Yakut Tahsin , Bekar Ahmet , Egeli Unal , Doygun Muammer , Ercan İlker , Yigit Barboros , Ogul Erhan 
Published: November 2004

AbstractWe investigated for aneuploidy of chromosomes 7, 9, 10, 17, and p‐53 gene deletions in 36 glial tumor tissues, using interphase fluorescence in sity hybridization (FISH), and compared the frequencies of abnormalities between low and high grade tumors. Among the 13 low grade tumors; 1 had trisomy 7, 1 had monosomy 9, 2 had monosomy 10, 1 had monosomy 17, 1 had p53 deletion, and among the 23 high grade tumors; 10 had trisomy 7, 1 had monosomy 9, 7 had monosomy 10, 2 had monosomy 17, 6 had p 53 deletion. The results indicated that neither aneuploidy of chromosome 9, nor chromosome 17 are prominent findings between low or high grade of glial tumors, although high‐grade glial tumors have higher rates of trisomy 7 (43.5%), monosomy 10 (30.4%) and p53 (26%) deletion than low‐grade ones. Statistical results showed significant difference between trisomy 7 and high grade astorocytomas (p=0.031). Considering these chromosomal abnormalities we suggest that trisomy 7, loss of chromosome 10 and alterations of the p53 gene have important role associated with glial tumor development and trisomy 7 is the most important genetic changes associated with glial tumor progression.
Influence of prenatal noise and music on the 5‐hydroxytryptamine synthesis and the tryptophan hydroxylase expression in the raphe nuclei of young rats
Authors: Kim Eun‐Kyung , Kim Hong , Lee Myoung‐Hwa , Kim Young‐Sick , Yang Hye‐Young , Chang Hyun‐Kyung , Lee Taeck‐Hyun , Jang Mi‐Hyeon , Shin Min‐Chul , Lee Sam‐Jun , Lee Hee‐Hyuk , Shin Mal‐Soon , Kim Chang‐Ju 
Published: November 2004

AbstractDuring the prenatal period, development of individual is influenced by the environmental factors. In mammals, 5‐hydroxytryptamine (5‐HT) is a central neurotransmitter that regulates behavioral functions in the vertebrate brain. Tryptophan hydroxylase (TPH) is a rate‐limiting enzyme in the 5‐HT synthesis. Various stresses are known to modulate the 5‐HT synthesis and the TPH expression. In the present study, the influence of prenatal noise and music aplication on the 5‐HT synthesis and the TPH expression in the dorsal and median raphe of young rats was investigated. Prenatal noise application increased the 5‐HT synthesis and the TPH expression in the dorsal and median raphe nuclei of offspring. Prenatal music application, in contrast, decreased the 5‐HT synthesis and the TPH expression in the dorsal and median raphe nuclei of offspring. The present study suggests that prenatal stimuli including noise and music may affect the emotional state of offspring.
Minimum fuel powered dynamic soaring of unmanned aerial vehicles utilizing wind gradients
Authors: Zhao Yiyuan J. , Qi Ying Celia 
Published: November 2004

AbstractThis paper studies optimal powered dynamic soaring flights of unmanned aerial vehicles (UAVs) that utilize low‐altitude wind gradients for reducing fuel consumptions. Three‐dimensional point‐mass UAV equations of motion are used, and linear wind gradients are assumed. Fundamental UAV performance parameters are identified through the normalization of the equations of motion. In particular, a single wind condition parameter is defined that represents the combined effect of air density, UAV wing loading, and wind gradient slope on UAV flight. An optimal control problem is first used to determine bounds on wind conditions over which optimal powered dynamic soaring is meaningful. Then, powered UAV dynamic soaring flights through wind gradients are formulated as non‐linear optimal control problems. For a jet‐engined UAV, performance indices are selected to minimize the average thrust required per cycle of powered dynamic soaring that employs either variable or constant thrust. For a propeller‐driven UAV, in comparison, performance indices are selected to minimize the average power required per cycle of powered dynamic soaring with either variable or constant power. All problem formulations are subject to UAV equations of motion, UAV operational constraints, proper initial conditions, and terminal conditions that enforce a periodic flight. These optimal control problems are converted into parameter optimization with a collocation method and solved numerically using the parameter optimization software NPSOL. Analytical gradient expressions are derived for the numerical solution process. Extensive numerical solutions are obtained for a wide range of wind conditions and UAV performance parameters. Results reveal basic features of powered dynamic soaring flights through linear wind gradients. Copyright © 2004 John Wiley & Sons, Ltd.
Polyhedral risk measures in electricity portfolio optimization
Authors: Eichhorn Andreas , Römisch Werner , Wegner Isabel 
Published: November 2004

AbstractWe compare different multiperiod risk measures taken from the class of polyhedral risk measures with respect to the effect they show when used in the objective of a stochastic program. For this purpose, simulation results of a stochastic programming model for optimizing the electricity portfolio of a German municipal power utility are presented and analyzed. This model aims to minimize risk and expected overall cost simultaneously. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Robust Process Control by Dynamic Stochastic Programming
Authors: Steinbach Marc C. 
Published: November 2004

AbstractUnnecessarily conservative behavior of standard process control techniques can be avoided by stochastic programming models when the distribution of random disturbances is known. In an earlier study we have investigated such an approach for tank level constraints of a distillation process. Here we address techniques that have accelerated the numerical solution of the large and expensive stochastic programs by a factor of six, and then present a refined optimization model for the same application. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Two‐step Schemes for SDEs with Small Noise
Authors: Buckwar Evelyn , Winkler Renate 
Published: November 2004

AbstractWe consider linear multi‐step methods for stochastic differential equations and present a theorem ensuring their numerical stability and strong convergence. We use this to study the properties of two‐step schemes for stochastic differential equations with small noise. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Optimization of Non‐Negative Density Solutions of Stationary Fokker‐Planck Equations
Authors: Wedig Walter V. 
Published: November 2004

AbstractClassical solution methods of Fokker‐Planck equations (see e.g. [1], [2], [3]) lead to negative densities at least in the tales where the density solutions strongly approach zero. To avoid these inconsistencies the paper proposes to apply central differences schemes in combination with large‐scaled quadratic optimization programming [4]. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling and Optimization of a Silicon Tuning Fork Gyroscope
Authors: Kugi A. , Thull D. , Seidel H. 
Published: November 2004

AbstractThis contribution deals with the systematic derivation of an analytical model for a silicon tuning fork gyroscope with piezoelectric drive and piezoresistive read‐out. The mathematical model serves as a basis for optimizing the overall sensor structure, for testing the electronic circuitry and for investigating the influence of disturbances, e.g. due to fabrication tolerances, on the measurement quality. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improved error estimates for a Maxwell‐Landau‐Lifschitz system
Authors: Slodička Marián , Cimrák Ivan 
Published: November 2004

AbstractWe study Maxwell's system coupled with the Landau‐Lifshitz (LL) equation. We consider the nonlinear dissipative case with a neglected exchange field. For a recent numerical scheme conserving magnitude of the magnetization we derive new error estimates and establish a better rate of convergence. These theoretical results are demonstrated on a numerical example. For computations we use the software package ALBERT. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of UV irradiation on physico‐mechanical properties of EPDM/buckminsterfullerene composite
Authors: Jin Wonseop , Kader M. Abdul , Ko Weon‐Bae , Nah Changwoon 
Published: November 2004

AbstractEthylene propylene diene rubber‐fullerene (EPDM/C60) composite, partially crosslinked by ultraviolet (UV) radiation, was prepared and characterized for crosslink density, mechanical properties and thermal behavior. FT‐IR analysis showed peak disappearance at 1688 cm−1, corresponding to the unsaturation of EPDM, and the appearance of new peaks relating to the formation of oxidation products of C60, such as epoxide, keto, aldehyde and carboxylic groups. Solubility studies demonstrated the dissolution of pristine EPDM in toluene even after a longer period of UV exposure, whereas EPDM/C60 composite became insoluble and/or swollen after 6 hr of UV exposure, indicating the formation of partial crosslinking between EPDM and C60. Differential scanning calorimetry (DSC) measurements revealed an increase in the glass transition temperature peak of UV‐cured EPDM. Thermogravimetric analysis (TGA) showed that UV exposure reduced the thermal decomposition temperature of EPDM/C60, pristine EPDM and dicumyl peroxide (DCP)‐cured EPDM. The modulus, tensile stress and elongation at break of EPDM/C60 composites were greatly influenced by the duration of UV irradiation. Comparison of UV‐cured EPDM/C60 composite with DCP‐cured EPDM confirmed the superior strength properties of the former system. Copyright © 2004 John Wiley & Sons, Ltd.
HPLC investigation of water soluble ternary polyacrylic acid‐Cu2+‐protein complexes
Authors: Taşdelen Betül Dinçer , Bayülken Seval 
Published: November 2004

AbstractIn this present work, complex formation of polyacrylic acid (PAA) with bovine serum albumin (BSA) in the presence of divalent copper ions (Cu2+) was investigated using high performance liquid chromatography (HPLC). HPLC results determined the most suitable metal concentration and protein/polymer ratio for maximum complex formation between polymer and protein molecules. Copyright © 2004 John Wiley & Sons, Ltd.
Pathogen‐induced actin filament rearrangement in infectious diseases
Authors: Rottner Klemens , Lommel Silvia , Wehland Jürgen , Stradal Theresia EB 
Published: November 2004

AbstractHost defence mechanisms involve the establishment and maintenance of numerous barriers to infectious microbes, including skin and mucosal surfaces, connective tissues, and a sophisticated immune system to detect and destroy invaders. Defeating these defence mechanisms and breaching the cell membrane barrier is the ultimate challenge for most pathogens. By invading the host and, moreover, by penetrating into individual host cells, pathogens gain access to a protective niche, not only to avoid immune clearance, but also to replicate and to disseminate from cell to cell within the infected host. Many pathogens are accomplishing these challenges by exploiting the actin cytoskeleton in a highly sophisticated manner as a result of having evolved common as well as unique strategies. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.