bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic lung morphology of methacholine‐induced heterogeneous bronchoconstriction
Authors: Chen Ben T. , Johnson G. Allan 
Published: November 2004

AbstractHyperpolarized (HP) 3helium (3He) dynamic MRI was used to investigate airway response in rats following intravenous (i.v.) bolus administration of a contractile agent, methacholine (MCh). The method provides direct visualization of the ventilated regions within the lung. Heterogeneous bronchoconstriction following the i.v. MCh injection was evident using this technique. These 3He dynamic lung images revealed that the inspired fresh air was shunted to the less‐constricted regions after the MCh challenge in a similar manner as described by Laplace's relationship for the stability between adjacent alveoli. The airways in the more‐constricted regions became nearly closed, resulting in air trapping, while the airways in the less‐constricted regions remained effectively open, leading to overinflation. These data suggest a lung model of airway constriction partitioned into ventilated and nonventilated regions. These nonventilated regions are heterogeneously distributed in the lung and this distribution cannot be deduced from spirometric measurement of the whole lung. We demonstrate that a combination of functional 3He images and anatomical 1H images provide an effective method to diagnose regional lung abnormalities in rats. Magn Reson Med 52:1080–1086, 2004. © 2004 Wiley‐Liss, Inc.
Quantitative analysis of diffusion tensor orientation: Theoretical framework
Authors: Wu Yu‐Chien , Field Aaron S. , Chung Moo K. , Badie Benham , Alexander Andrew L. 
Published: November 2004

AbstractDiffusion‐tensor MRI (DT‐MRI) yields information about the magnitude, anisotropy, and orientation of water diffusion of brain tissues. Although white matter tractography and eigenvector color maps provide visually appealing displays of white matter tract organization, they do not easily lend themselves to quantitative and statistical analysis. In this study, a set of visual and quantitative tools for the investigation of tensor orientations in the human brain was developed. Visual tools included rose diagrams, which are spherical coordinate histograms of the major eigenvector directions, and 3D scatterplots of the major eigenvector angles. A scatter matrix of major eigenvector directions was used to describe the distribution of major eigenvectors in a defined anatomic region. A measure of eigenvector dispersion was developed to describe the degree of eigenvector coherence in the selected region. These tools were used to evaluate directional organization and the interhemispheric symmetry of DT‐MRI data in five healthy human brains and two patients with infiltrative diseases of the white matter tracts. In normal anatomical white matter tracts, a high degree of directional coherence and interhemispheric symmetry was observed. The infiltrative diseases appeared to alter the eigenvector properties of affected white matter tracts, showing decreased eigenvector coherence and interhemispheric symmetry. This novel approach distills the rich, 3D information available from the diffusion tensor into a form that lends itself to quantitative analysis and statistical hypothesis testing. Magn Reson Med 52:1146–1155, 2004. © 2004 Wiley‐Liss, Inc.
Correction of high‐order eddy current induced geometric distortion in diffusion‐weighted echo‐planar images
Authors: Shen Yuji , Larkman David J. , Counsell Serena , Pu Ida M. , Edwards David , Hajnal Joseph V. 
Published: November 2004

AbstractDiffusion‐weighted images acquired with the echo‐planar imaging technique are highly sensitive to eddy current induced geometric distortions that vary with the magnitude and direction of the diffusion sensitizing gradients. Such distortions cause misalignment of images acquired with different diffusion strengths and orientations. This in turn can result in errors when calculating maps of the apparent diffusion coefficient and diffusion tensor. Previous correction methods either require separate calibration data or only deal with low‐order errors. In this study, we demonstrate a method that can correct for higher‐order errors. The method relies on collecting pairs of images with diffusion sensitizing gradients reversed. This paired data are first corrected for shifts and linear distortion and then combined to cancel higher‐order errors. All acquired data contribute to the final results. The method has been tested by simulation, on phantoms, on adult volunteers, and on neonatal brain examinations. Magn Reson Med 52:1184–1189, 2004. © 2004 Wiley‐Liss, Inc.
Modeling and analyzing multiple station baggage screening security system performance
Authors: Jacobson Sheldon H. , McLay Laura A. , Kobza John E. , Bowman Jon M. 
Published: November 2004

AbstractIn the aftermath of the tragic events of 11 September 2001, numerous changes have been made to aviation security policy and operations throughout the nation's airports. The allocation and utilization of checked baggage screening devices is a critical component in aviation security systems. This paper formulates problems that model multiple sets of flights originating from multiple stations (e.g., airports, terminals), where the objective is to optimize a baggage screening performance measure subject to a finite amount of resources. These measures include uncovered flight segments (UFS) and uncovered passenger segments (UPS). Three types of multiple station security problems are identified and their computational complexity is established. The problems are illustrated on two examples that use data extracted from the Official Airline Guide. The examples indicate that the problems can provide widely varying solutions based on the type of performance measure used and the restrictions imposed by the security device allocations. Moreover, the examples suggest that the allocations based on the UFS measure also provide reasonable solutions with respect to the UPS measure; however, the reverse may not be the case. This suggests that the UFS measure may provide more robust screening device allocations. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2005.
Potentiation of (DL)‐3,4‐methylenedioxymethamphetamine (MDMA)‐induced toxicity by the serotonin 2A receptior partial agonist d‐lysergic acid diethylamide (LSD), and the protection of same by the serotonin 2A/2C receptor antagonist MDL 11,939
Authors: Armstrong Brian D. , Paik Elena , Chhith Seririthanar , Lelievre Vincent , Waschek James A. , Howard Sherrel G. 
Published: November 2004

AbstractTo elucidate the role of the serotonin (5‐HT)2A/2C receptors in 3,4‐methylenedioxymethamphetamine (MDMA)‐induced neurotoxicity, MDMA was administered to rats and the presence of the serotonin transporter (5‐HTT) was assessed at the protein level with immunohistochemistry (IHC), and the RNA level with a Northern blotting technique. d‐lysergic acid diethylamide (LSD) and MDL 11,939 were given in conjunction with MDMA in order to assess the importance of 5‐HT receptors in MDMA‐induced neurotoxicity. The hypothesis is that the MDMA + LSD‐treated animals should have more neurotoxicity as measured by loss of 5‐HTTs compared to the MDMA‐treated animals. Moreover, the loss of 5‐HTTs should be attenuated in animals given the combination of MDMA + MDL 11,939, as the latter drug is a selective 5‐HT2A/2C antagonist. The results showed that MDMA‐induced neurotoxicity was dose dependently increased by LSD. Moreover, the drug MDL 11,939 attenuated MDMA‐induced neurotoxicity, suggesting that 5‐HT2A/2C receptors are involved in MDMA‐induced neurotoxicity.
Effect of two different cytoprotectives, ethiofos and β‐NGF, on cisplatin‐induced toxicity in Schwann cell cultures; a preliminary study
Authors: Jirsová K. , Mandys V. , Bär P.R. 
Published: November 2004

AbstractTwo cytoprotective agents, ethiofos (WR2721) and nerve growth factor (NGF), were used to diminish cisplatin‐induced toxicity in Schwann cell cultures. The effect of both studied agents was estimated by a micronucleus test and the comet assay. The comet assay was performed in cultured human Schwann cells isolated from sural nerve biopsies, and the micronucleus test was used in primary cultures of Schwann cells isolated from foetal rat dorsal root ganglia (DRG). A dose‐dependent increase in the number of cells displaying DNA damage was found at both concentrations of cisplatin, 0.5 and 1.0 μM. No significant protective effect of either β‐NGF or WR‐2721 was observed in human Schwann cell cultures. A significant protective effect was obtained in the cultures of Schwann cells isolated from foetal rat DRG, when treated simultaneously with 0.5 μM cisplatin and 10 ng/ml β‐NGF. WR‐2721 was not effective in these cells.
Effects of 5‐HT1 receptor agonist on the excitability of medial vestibular nuclear neurons
Authors: Park Jong‐Seong , Jeong Han‐Seong , Kim Tae‐Sun , Kim Yo‐Sik , Kim Jae‐Ha , Jang Myung‐Joo , Kim Ja‐Yeon , Huang Mei 
Published: November 2004

AbstractThe aim of this study is to explore the action of 5‐HT1 receptor on spontaneous firing activity of the rat medial vestibular nuclear neurons by patch clamp experiments. The spontaneous firing was increased in 45.5% and decreased in 54.5% of the neurons tested with 5‐carboxamidotryptamine, non‐selective 5‐HT1 receptor agonist. And the whole potassium currents of medial vestibular nuclear neurons was decreased in 64% and increased in 36% of cells tested with 5‐carboxamidotryptamine. The spontaneous firing rate was increased by 8‐OH‐DPAT, selective 5‐HT1A receptor agonist in 73.3% and was not changed in 26.7%. Whole potassium currents were decreased in 84.2% and was not affected in 15.8% by 8‐OH‐DPAT. These results suggest that 5‐HTIA receptor of the medial vestibular nuclear neurons mediates excitatory effects whereas inhibitory effects are mediated by other 5‐HT1 receptors.
Ouabain‐induced reversal of astrocytic GLT‐1 crucial to neuronal death in neuron/astrocyte co‐cultures
Authors: Tanaka Motoki , Kawahara Koichi , Hosoya Rui , Kosugi Tatsuro , Nakajima Takayuki , Yamada Takeshi 
Published: November 2004

AbstractWe investigated whether the role of the astrocytic glutamate transporter GLT‐1 is reversed when the ionic gradient across plasma membrane has collapsed, and if so, whether the reversal is crucial to neuronal death. To estimate the direction of glutamate transport by GLT‐1, Na+ movement coupled with glutamate transport in astrocytes was analyzed in mixed astrocyte/neuron cultures. The rise in astrocytic intracellular Na+ due to glutamate exposure was suppressed by co‐treatment with dihydrokainate (DHK). In contrast, the ouabain‐induced rise in Na+ was significantly enhanced by DHK, suggesting that the role of GLT‐1 was reversed. We then analyzed whether the reversal increased the amount of extracellular glutamate, and was crucial to excitotoxic neuronal death. Ouabain treatment resulted in a marked rise in glutamate and in neuronal death, and both the rise and cell death were significantly attenuated by DHK treatment.
A general effective method for combining collocation and DDM: An application of discontinuous Galerkin methods
Authors: Herrera Ismael , Yates Robert 
Published: November 2004

AbstractDomain decomposition methods (DDM) have received much attention in recent years. They constitute the most effective means of using parallel computing resources to model continuous systems. However, combining collocation procedures with domain decomposition methods presents complications that must be overcome in order to profit from the advantages of parallel computing. The present paper belongs to a line of research in which a theory that constitutes a general and systematic formulation of discontinuous Galerkin methods (dG) is being investigated. Based on it, a new method of collocation of general applicability, TH‐collocation, was recently introduced. For a broad class of symmetric and positive continuous systems, TH‐collocation yields symmetric and positive matrices. This clears the way for applying effectively DDM and parallel computing, in combination with collocation, to such systems. In this paper the general procedure is explained with some detail and then is applied to develop an effective method for processing elliptic equations of second order. This, by the way, overcomes the difficulties encountered in a previous Herrera and Pinder's article. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005.
The great auk (Pinguinus impennis) in the Netherlands during the Roman period
Authors: Groot M. 
Published: November 2004

AbstractBones of the great auk (Pinguinus impennis) have been found in four archaeological sites in the Netherlands in recent years. These sites all date to the early Roman period. The great auk is believed never to have been a breeding bird in the Netherlands, which makes the presence of the bones remarkable. The history and ecology of the great aukare outlined. Some possible reasons are discussed for the presence of the great auk in Dutch waters during the early Roman period. Copyright © 2004 John Wiley & Sons, Ltd.
Robust continuous‐time controller design via structural Youla–Kučera parameterization with application to predictive control
Authors: Kowalczuk Z. , Suchomski P. 
Published: November 2004

AbstractThis paper addresses the continuous‐time control of uncertain linear SISO plants and its nominal and robust stability and nominal and robust performance objectives. A specific application of the Youla–Kučera (Q) parameterization concept leads to a new development of observer‐like controller structures. This method is combined with a nominal design of continuous‐time generalized predictive control suitable for both minimum‐phase and non‐minimum‐phase plants. The subsequent design procedure consists of two steps. Firstly, the nominal stability and nominal performance of the control system are established by using an analytical design methodology, based on a collection of closed‐loop prototype characteristics with definite time‐domain specifications. And secondly, a generic structure of the controller is enhanced by suitable Q‐parameters guaranteeing that the control system has the required robustness properties. The proposed structural (reduced‐order) Q‐parameterization relies on an observer structure of controllers, which can be easily enhanced with certain filters necessary for control robustification. To reduce the complexity of the resulting robust controllers, we suggest using a structural factorization, which allows for simple forms of robustifying (phase‐lag) correctors of low order, easy for implementation, and convenient for optimization and tuning. Two numerical examples are given to illustrate the composed technique and its practical consequences. Copyright © 2004 John Wiley & Sons, Ltd.
Mean‐risk optimization of electricity portfolios
Authors: Eichhorn Andreas , Gröwe‐Kuska Nicole , Liebscher Andrea , Römisch Werner , Spangardt Gorden , Wegner Isabel 
Published: November 2004

AbstractWe present a mathematical model with stochastic input data for mean‐risk optimization of electricity portfolios containing several physical components and energy derivative products. The model is designed for the optimization horizon of one year in hourly discretization. The aim consists in maximizing the mean book value of the portfolio at the end of the optimization horizon and, at the same time, in minimizing the risk of the portfolio decisions. The risk is measured by the conditional value‐at‐risk and by some multiperiod extension of CVaR, respectively.We present numerical results for a large‐scale realistic problem adapted to a municipal power utility and study the effects of varying weighting of risk. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parallel Strategies Applied to FE Simulations of Multiphasic Problems
Authors: Ehlers Wolfgang , Graf Tobias , Ammann Martin , Wieners Christian 
Published: November 2004

AbstractWhile the theoretical background of various porous media models is well understood, it is still a demanding task to deal with these models numerically. In this contribution, a triphasic model is presented, which is capable of describing partially saturated soils. In quasi‐static conditions, this model results in the primary variables solid displacement, pore‐liquid pressure and pore‐gas pressure. For a stable numerical implementation, Taylor‐Hood elements are required, which need quadratic ansatz functions for the displacement and linear ansatz functions for the pressure terms. Looking at numerical simulations in 2‐d, challenging finite element calculations have already been realized in combination with adaptivity in time and space [1]. Nevertheless, new strategies have to be considered for a realization of applications of the model in 3‐d in order to handle the huge amount of unknowns arising from the discretization with Taylor‐Hood elements. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some Remarks on Modelling and Simulation of Thin Film Flow
Authors: Becker Jürgen , Grün Günther 
Published: November 2004

AbstractRecenty, convergent and nonnegativity preserving numerical schemes for the thin film equation have been developed and applied successfully to model the flow of thin films of Newtonian liquids on homogeneous surfaces. It is the aim of this paper to discuss two related, but more involved physical settings. The first topic is flow on chemically structured surfaces which is of great interest in a number of microfluidic applications. We will formulate a convergent, nonnegativity preserving scheme and compare the simulations with recent physical experiments. The second part deals with power‐law‐fluids. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modified carrageenan. 5. Preparation, swelling behavior, salt‐ and pH‐sensitivity of partially hydrolyzed crosslinked carrageenan‐graft‐polymethacrylamide superabsorbent hydrogel
Authors: Pourjavadi A. , Sadeghi M. , Hosseinzadeh H. 
Published: November 2004

AbstractThe polysaccharide, kappa‐carrageenan (κC) was chemically modified to achieve a novel superabsorbent hydrogel via graft copolymerization of methacrylamide (MAM) onto the substrate followed by alkaline hydrolysis. Ammonium persulfate (APS) and N,N′‐methylene bisacrylamide (MBA) were used as a free‐radical initiator and a crosslinker, respectively. The saponification reaction was carried out using sodium hydroxide aqueous solution. Either κC‐g‐PMAM or hydrolyzed κC‐g‐PMAM (PMAM: polymethacrylamide) was characterized by FT‐IR spectroscopy. The effect of grafting variables (i.e. concentration of MBA, MAM, and APS) and alkaline hydrolysis conditions (i.e. NaOH concentration, hydrolysis time and temperature) were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The swelling capacity of these hydrogels was also measured in various salt solutions. Results indicated that the swelling ratios decreased with an increase in the ionic strength of the salt solutions. This behavior can be attributed to charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations. Absorbency of superabsorbing hydrogels was examined in buffer solutions with pH range 1–13. Also, the pH reversibility and on–off switching behavior, at pH values 3.0 and 8.0, makes the synthesized hydrogels good candidates for controlled delivery of bioactive agents. Finally, swelling kinetics in distilled water and various salt solutions was preliminary investigated. Results showed that the swelling in water was faster than in saline solutions. Copyright © 2004 John Wiley & Sons, Ltd.
UV curable waterborne polyurethane acrylate dispersions based on hyperbranched aliphatic polyester: effect of molecular structure on physical and thermal properties
Authors: Asif Anila , Shi Wenfang 
Published: November 2004

AbstractA novel waterborne hyperbranched polyurethane acrylate for aqueous dispersions (WHPUDs) based on hydroxy‐functionalized hyperbranched aliphatic polyester Boltorn™ H20 was investigated. The effects of structural composition and crosslinking density have been studied in terms of swellability by water, thermal degradation, viscosity changes as well as transmission electron microscopy (TEM) morphology. The swell ratio showed an increasing trend with the higher concentration of ionic group, which is due to the increased total surface area of particles. The results of thermogravimetric analysis (TGA) for cured WHPUD films indicated good thermal stability with no appreciable weight loss until 200°C. The activation energies were evaluated and were found in the range 154–186 kJ mol−1. It was observed that an increase in hard segment content provoked the increases in thermal degradation temperature and activation energy of waterborne dispersions. The transmission electron photographs revealed that the average particle sizes of aqueous dispersions were in the range 30–125 nm. Owing to the enlargement of the stabilization site, the particle size decreased as the content of carboxyl group and degree of neutralization increased. The viscosity of WHPUDs increased rapidly with increasing the degree of neutralization. Moreover, water showed a favorable viscosity reduction effect. Copyright © 2004 John Wiley & Sons, Ltd.
Hereditary haemolytic anaemias: unexpected sequelae of mutations in the genes for erythroid membrane skeletal proteins
Authors: Birkenmeier Connie S , Barker Jane E 
Published: November 2004

AbstractAlthough the haemolytic anaemia may be the primary concern for hereditary spherocytosis and elliptocytosis patients, it is clear that their situation can be compromised by primary and secondary defects in erythroid and non‐erythroid systems of the body. All seven of the red cell membrane skeletal proteins discussed in this review are also expressed in non‐erythroid tissues, and mutations in their genes have the potential to cause non‐erythroid defects. In some instances, such as the protein 4.1R and ANK1 neurological deficits, the diagnosis is clear. In other instances, because of the complex expression patterns involved, the non‐erythroid effects may be difficult to assess. An example is the large multidomain, multifunctional band 3 protein. In this case, the location of the mutation can cause defects in one functional domain or isoform and not the other. In other cases, such as the beta‐adducin null mutation, other isoforms may partially compensate for the primary deficiency. In such cases, it may be that the effects of the deficit are subtle but could increase under stress or with age. To be completely successful, treatment strategies must address both primary and secondary effects of the anaemia. If gene replacement therapy is to be used, the more that is known about the underlying genetic mechanisms producing the multiple isoforms the better we will be able to design the best replacement gene. The various animal models that are now available should be invaluable in this regard. They continue to contribute to our understanding of both the primary and the secondary effects and their treatment. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.