bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and analysis of power‐CMOS‐gate‐based switched‐capacitor DC–DC converter with step‐down and step‐up modes
Authors: Chang Yuen‐Haw
Published: January 2005

A unified multi‐stage power‐CMOS‐transmission‐gate‐based quasi‐switched‐capacitor (QSC) DC–DC converter is proposed to integrate both step‐down and step‐up modes all in one circuit configuration for low‐power applications. In this paper, by using power‐CMOS‐transmission‐gate as a bi‐directional switch, the various topologies for step‐down and step‐up modes can be integrated in the same circuit configuration, and the configuration does not require any inductive elements, so the IC fabrication is promising for realization. In addition, both large‐signal state‐space equation and small‐signal transfer function are derived by state‐space averaging technique, and expressed all in one unified formulation for both modes. Based on the unified model, it is all presented for control design and theoretical analysis, including steady‐state output and power, power efficiency, maximum voltage conversion ratio, maximum power efficiency, maximum output power, output voltage ripple percentage, capacitance selection, closed‐loop control and stability, etc. Finally, a multi‐stage QSC DC–DC converter with step‐down and step‐up modes is made in circuit layout by PSPICE tool, and some topics are discussed, including (1) voltage conversion, output ripple percentage, and power efficiency, (2) output robustness against source noises and (3) regulation capability of converter with loading variation. The simulated results are illustrated to show the efficacy of the unified configuration proposed. Copyright © 2003 John Wiley & Sons, Ltd.
Analysis, modelling and optimization of a gain boosted telescopic amplifier
Authors: Aloisi W. , Giustolisi G. , Palumbo G.
Published: January 2005

In this paper, a thorough analysis of a gain‐boosted telescopic amplifier (GBTA) is presented and a systematic design procedure for optimizing its time response will be given. Specifically, the GBTA closed‐loop time response will be analysed in detail and the constraints eliminating the well‐known ‘slow settling component’ found. Subsequently, an optimization strategy based on the comparison between the GBTA time response and the time response of a pure two‐pole amplifier (referred to as the target system) will be described. This strategy allows the designer to develop a GBTA starting from the target system specifications in a simple and systematic way. The proposed procedure has been validated by means of simulations and excellent agreement found between the simulated and the expected results. Copyright © 2003 John Wiley & Sons, Ltd.
Modelling, design and realization of micromachined millimetre‐wave band‐pass filters
Authors: Bartolucci Giancarlo , Neculoiu Dan , Dragoman Mircea , Giacomozzi Flavio , Marcelli Romolo , Müller Alexandru
Published: January 2005

This paper describes the design, the realization and the experimental characterization of a micromachined band‐pass filter with a working frequency of 38GHz. The synthesis of the structure has been carried out by means of the image parameter representation of two‐port networks. A coupled line coplanar configuration has been adopted for the filtering network. The good agreement between theoretical and experimental results demonstrates the validity of the proposed design approach. Copyright © 2003 John Wiley & Sons, Ltd.
First direct implementation of a true random source on programmable hardware
Authors: Callegari S. , Rovatti R. , Setti G.
Published: January 2005

True random sources are not implementable in digital hardware, so that many practical applications have historically relied on pseudo‐random generators in order to avoid the potentially long prototyping times and the costs of dedicated analog design. However, pseudo‐random sources have liabilities that make them hardly suitable for some tasks (notably security related ones). Previous attempts to conciliate security, cost‐effectiveness, and rapid development included the exploitation of the analog accessory parts often present on programmable devices. In these designs some analog blocks are used for their side effects (noise amplification) rather than for their originally intended behaviour. Conversely, here we report adirectimplementation of a true random source on programmable, low‐cost, general‐purpose hardware, where all blocks are used only for their nominal function. To the best of the authors' knowledge, this is the first proposal of this sort. The design exploits an FPAA, and is based on a non‐linear system exhibiting chaotic behaviour. Measures confirm the correct operation, high throughput, and robustness of the system. Copyright © 2005 John Wiley & Sons, Ltd.
Pixel‐level snakes on the CNNUM: algorithm design, on‐chip implementation and applications
Authors: Vilariño David L. , Rekeczky Csaba
Published: January 2005

In this paper, a new algorithm for the cellular active contour technique called pixel‐level snakes is proposed. The motivation is twofold: on the one hand, a higher efficiency and flexibility in the contour evolution towards the boundaries of interest are pursued. On the other hand, a higher performance and suitability for its hardware implementation onto a cellular neural network (CNN) chip‐set architecture are also required. Based on the analysis of previous schemes the contour evolution is improved and a new approach to manage the topological transformations is incorporated. Furthermore, new capabilities in the contour guiding are introduced by the incorporation of inflating/deflating terms based on the balloon forces for the parametric active contours. The entire algorithm has been implemented on a CNN universal machine (CNNUM) chip set architecture for which the results of the time performance measurements are also given. To illustrate the validity and efficiency of the new scheme several examples are discussed including real applications from medical imaging. Copyright © 2005 John Wiley & Sons, Ltd.
CNN‐based architecture for real‐time object‐oriented video coding applications
Authors: Grassi Giuseppe , Grieco Luigi A.
Published: January 2005

This paper presents a new CNN‐based architecture for real‐time video coding applications. The proposed approach, by exploiting object‐oriented CNN algorithms and MPEG encoding capabilities, enables low bit‐rate encoder/decoder to be designed. Simulation results using Claire video sequence show the effectiveness of the proposed scheme. Copyright © 2005 John Wiley & Sons, Ltd.
Input and system identification of the Hualien soil–structure interaction system using earthquake response data
Authors: Choi Jun‐Seong , Lee Jong Seh , Yun Chung‐Bang
Published: January 2005

This paper presents an input and system identification technique for a soil–structure interaction system using earthquake response data. Identification is carried out on the Hualien large‐scale seismic test structure, which was built in Taiwan for international joint research. The identified quantities are the input ground acceleration as well as the shear wave velocities of the near‐field soil regions and Young's moduli of the shell sections of the structure. The earthquake response analysis on the soil–structure interaction system is carried out using the finite element method incorporating the infinite element formulation for the unbounded layered soil medium and the substructured wave input technique. The criterion function for the parameter estimation is constructed using the frequency response amplitude ratios of the earthquake responses measured at several points of the structure, so that the information on the input motion may be excluded. The constrained steepest descent method is employed to obtain the revised parameters. The simulated earthquake responses using the identified parameters and input ground motion show excellent agreement with the measured responses. Copyright © 2003 John Wiley & Sons, Ltd.
Adaptive bang–bang control for the vibration control of structures under earthquakes
Authors: Lim C. W. , Chung T. Y. , Moon S. J.
Published: January 2005

An adaptive method based on the modified bang–bang control algorithm is proposed for the vibration control of structures subjected to unexpected severe seismic loads greater than the design loads. A hydraulic‐type active mass damper was made and experiments were carried out in the laboratory using a one‐story test structure and a five‐story test structure with the active mass damper. Through numerical simulations and experiments it was confirmed that the proposed method works well to suppress the vibration of structures subjected to unexpected severe seismic loads greater than the design loads without causing any unstable situations. Copyright © 2003 John Wiley & Sons, Ltd.
Cyclic tests on large‐scale models of existing bridge piers with rectangular hollow cross‐section
Authors: Pinto A. V. , Molina J. , Tsionis G.
Published: January 2005

Cyclic tests on two large‐scale models of existing bridge piers with rectangular hollow cross‐section were performed in the ELSA laboratory. The prototype structure is an existing reinforced concrete highway bridge constructed in Austria in 1975. The piers presented several seismic deficiencies and consequently they showed poor hysteretic behaviour and limited deformation capacity as well as undesirable failure modes that do not comply with the requirements of modern codes for seismic‐resistant structures. Experimental data are compared to numerical and empirical predictions. Copyright © 2003 John Wiley & Sons, Ltd.
An improved capacity spectrum method for ATC‐40
Authors: Lin Yu‐Yuan , Chang Kuo‐Chun
Published: January 2005

In order to account for the non‐linear behavior of structures via non‐linear static procedure, the capacity spectrum method has been adopted by ATC‐40 for evaluation and retrofit of reinforced concrete buildings. For elastic‐perfectly‐plastic SDOF systems, the accuracy of the capacity spectrum method depends only on the acceleration response spectrum chosen to form the demand spectrum and the adopted model for calculating the equivalent viscous damping ratios. According to this method, the pseudo‐acceleration response spectrum (PSa) is used to create the demand diagram. It is found that the ATC‐40 procedure, using its Type A hysteretic model, may be inaccurate especially for systems with damping ratios greater than 10% and periods longer than 0.15sec. In order to improve the accuracy of the capacity spectrum method, this study proposes to use the real absolute acceleration response spectrum (S0.a) instead of the PSa to establish the demand diagram. The step‐by‐step procedure of the improved method and examples are implemented in this paper to illustrate the calculations of earthquake‐induced deformations. In addition, three selected models of equivalent viscous damping are also compared in this paper to assess the accuracy of the model used in the ATC‐40 procedure. Results show that the WJE damping model may be used by the capacity spectrum method to reasonably predict the inelastic displacements when the ductility demand (μ) of the structures is less than 4, whereas the damping model proposed by Kowalsky can be implemented when μ>4.0. Alternatively, the damping model proposed by Kowalsky may be used to calculate the equivalent viscous damping for the entire range of ductility. Copyright © 2003 John Wiley & Sons, Ltd.
Seismic collapse analysis of reinforced concrete framed structures using the finite element method
Authors: Isobe Daigoro , Tsuda Michihiro
Published: January 2005

A new finite element code using the Adaptively Shifted Integration (ASI) technique with a linear Timoshenko beam element is applied to the seismic collapse analysis of reinforced concrete (RC) framed structures. This technique can express member fracture as a plastic hinge located at either end of an element with simultaneous release of the resultant forces in the element. Contact between members is also considered in order to obtain results that agree more closely with actual behavior, such as intermediate‐layer failure. By using the proposed code, sufficiently reliable solutions have been obtained, and the results reveal that this code can be used in the numerical estimation of the seismic design of RC framed structures. Copyright © 2003 John Wiley & Sons, Ltd.
Numerical study of the seismic behaviour of a part of the Parthenon Pronaos
Authors: Psycharis I. N. , Lemos J. V. , Papastamatiou D. Y. , Zambas C. , Papantonopoulos C.
Published: January 2005

A numerical study of the seismic behaviour of a proposed restoration of the Parthenon Pronaos is presented. The column‐architrave classical structure was represented by a discrete element model, with the assumption of rigid blocks and frictional joints. Time domain analyses were performed, considering the geometric and material non‐linear behaviour at the joints. The deformation and failure modes of drum columns subject to seismic excitations of various types and intensities were analysed. The adverse influence of drum imperfections on structural safety was examined. A proposal of reinforcement with titanium connections was analysed, and it was found that architrave connections generally improve the response by decreasing the permanent displacements, while titanium dowels between the column drums do not improve significantly the behaviour and in some cases they may be unfavourable to the safety of the structure. Copyright 2003 John Wiley & Sons, Ltd.
Experimental verification of torsional response control of asymmetric buildings using MR dampers
Authors: Yoshida Osamu , Dyke Shirley J. , Giacosa Luca M. , Truman Kevin Z.
Published: January 2005

This paper proposes a semiactive control system to reduce the coupled lateral and torsional motions in asymmetric buildings subjected to horizontal seismic excitations. Magnetorheological (MR) dampers are applied as semiactive control devices and the control input determination is based on a clipped‐optimal control algorithm which uses absolute acceleration feedback. The performance of this method is studied experimentally using a 2‐story building model with an asymmetric stiffness distribution. An automated system identification methodology is implemented to develop a control‐oriented model which has the natural frequencies observed in the experimental system. The parameters for the MR damper model are identified using experimental data to develop an integrated model of the structure and MR dampers. To demonstrate the performance of this control system on the experimental structure, a shake table is used to reproduce an El Centro 1940 N–S earthquake as well as a random white noise excitation. The responses for the proposed control system are compared to those of passive control cases in which a constant voltage is applied to the MR damper. Copyright © 2003 John Wiley & Sons, Ltd.
A method of coupling non‐linear hyperbolic systems: examples in CFD and plasma physics
Authors: Godlewski E. , Raviart P. A.
Published: January 2005

This paper analyses a method of coupling systems of conservation laws with examples in two fluid flows. Copyright © 2005 John Wiley & Sons, Ltd.
Reduced basis simulations as a tool for generating turbulent inlet‐data for two opposing jets
Authors: Johansson Peter S. , Andersson Helge I.
Published: January 2005

Reduced basis simulations are used in order to generate turbulent inlet boundary conditions for a direct numerical simulation of two opposing wall jets. The two entering jets are fully turbulent channel flows of Reynolds number 180, based on friction velocity and half channel height. The inflow turbulence is generated by solving dynamical equations for the large scales only, while less energetic small scales are added randomly. The proper orthogonal decomposition method is used to identify the large scale modes used in the basis set. Mean velocity and turbulence statistics have been reported in various planes of the interaction region and the outwash jet. The increase in maximum turbulence energy from the inlet jet to the stagnation region is about 500%. The spreading rate of the merged jet was found to be 0.125. Copyright © 2005 John Wiley & Sons, Ltd.
On optimization, control and shape design of an arterial bypass
Authors: Rozza Gianluigi
Published: January 2005

Multi‐level geometrical approaches in the study of aorto‐coronaric bypass anastomoses configurations are discussed. The theory of optimal control based on adjoint formulation is applied in order to optimize the shape of the incoming branch of the bypass (the toe) into the coronary. At this level, two possible options are available in shape design: one implements local boundary variations in computational domain, the other, based on the theory of small perturbations, makes use of a linearized design in a reference domain. At a coarser level, reduced basis methodologies based on parametrized partial differential equations are developed to provide (a) a sensitivity analysis for geometrical quantities of interest in bypass configurations and (b) rapid and reliable prediction of integral functional outputs. The aim is (i) to provide design indications for arterial surgery in the perspective of future development for prosthetic bypasses, (ii) to develop multi‐level numerical methods for optimization and shape design by optimal control, and (iii) to provide an input–output relationship led by models with lower complexity and computational costs. We have numerically investigated a reduced model based on Stokes equations and a vorticity cost functional (to be minimized) in the down‐field zone of bypass: a Taylor like patch has been found. A feedback procedure with Navier–Stokes fluid model is proposed based on the analysis of wall shear stress‐related indexes. Copyright © 2005 John Wiley & Sons, Ltd.
Preconditioners for inhomogeneous anisotropic problems in spherical geometry
Authors: Brown D. E. , Nichols N. K. , Bell M. J.
Published: January 2005

Elliptic equations arising in free‐surface ocean models are typically solved using iterative methods. Anisotropy associated with standard spherical co‐ordinate systems causes the convergence of the iterative methods to be slow, particularly in polar regions. This behaviour is demonstrated here using a diagonally preconditioned conjugate gradient method (PCG) method to solve a Helmholtz elliptic model problem with a standard five‐point discretization scheme on a 2D spherical domain. The cause of the poor polar convergence is shown to be the increased importance, with increased mesh anisotropy, of eigenmodes with strong polar signals. Block diagonal and alternating direction implicit (ADI) preconditioners are found to give improved convergence. Crown copyright 2005. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.
Adaptive particle distribution for smoothed particle hydrodynamics
Authors: Lastiwka Martin , Quinlan Nathan , Basa Mihai
Published: January 2005

A framework for adaptively inserting and removing particles with smoothed particle hydrodynamics (SPH) has been developed. A number of SPH variants were examined for use in an adaptive method. A minimum of linear consistency in the method has proven critical. Algorithms for particle placement and reassignment are discussed and results for a shock tube problem are shown. Copyright © 2005 John Wiley & Sons, Ltd.
Unsteady turbulent flow with sudden pressure gradient changes
Authors: Chung Yongmann M.
Published: January 2005

Direct numerical simulations are performed for a turbulent flow subjected to a sudden change in pressure gradient. The calculations are started from a fully developed turbulent channel flow at Reτ=180. The pressure gradient of the channel flow is then changed abruptly. The responses of the turbulence quantities (e.g. turbulence intensities, Reynolds shear stress, and vorticity fluctuations) and the near‐wall turbulence structure to the pressure gradient change are investigated. It is found that there are two different relaxations: a fast relaxation at the early stage and a slow one at the later stage. The early response of the velocity fluctuations shows an anisotropic response to the near‐wall turbulence. Copyright © 2005 John Wiley & Sons, Ltd.
Synthesis of some new azole, azepine, pyridine, and pyrimidine derivatives using 6‐hydroxy‐4H‐4‐oxo[1]‐benzopyran‐3‐ carboxaldehyde as a versatile starting material
Authors: Abdel‐Rahman A. H. , Hammouda M. A. A. , El‐Desoky S. I.
Published: January 2005

Condensation of 3‐formyl chromone 1 with hydroxylamine hydrochloride afforded the corresponding oxime 2 that was converted to nitrile 3. Refluxing of oxime 2 and/or nitrile 3 with aceturic or hippuric acid gave 16 and 17. Treatment of 1 with semicarbazide hydrochloride and thiosemicarbazide afforded the corresponding carbazones 5–6 that underwent cyclization with ethyl bromoacetate and/or chloroacetone yielding 7–8. Also 1 reacted with acyclic active methylene reagents, e.g. malononitrile, ethyl cyanoacetate, and ethyl acetoacetate to form compounds 11, 12, and 13. Reaction of 1 with bifunctional reagents, e.g. benzil, o‐phenylenediamine, o‐aminophenol, and o‐aminothiophenol yielding the corresponding imidazolyl bezopyranone and azepine derivatives 14–20. Condensation of 1 with acyclic or heterocyclic compounds containing active methylene group, e.g. hippuric acid forming the condensed products 21–27. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:20–27, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20048
Synthesis of novel chiral 2‐oxo‐ and 2‐thio‐1,3,2‐oxazaphospholidines via asymmetric cyclization of L‐methionol with (thio)phosphoryl dichlorides
Authors: Liu Ling‐yan , Chen Ru‐yu , Huang You
Published: January 2005

In order to search for novel antitumor and antiviral agents with high activity and low toxicity, a series of chiral 2‐thio(oxo)‐1,3,2‐oxazaphospholidines were synthesized via the reaction of L‐methionol with all kinds of (thio)phosphoryl dichlorides in THF in the presence of triethylamine at room temperature. The structures of all of the new compounds were confirmed by elemental analyses, 1H, 31P NMR, and IR spectra. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:33–38, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20060
Synthesis of substituted benzoindolinothiazepines using 5‐ and 6‐nitroindolines
Authors: Laconde G. , Depreux P. , Berthelot P. , Hénichart J.‐P.
Published: January 2005

Here is proposed a method of synthesis of benzoindolothiazepine compounds using Friedel‐ Crafts reactions conditions from indolines. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:39–43, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20063
One‐pot synthesis of pyridine derivatives via diels‐alder reactions of 2,4‐dimethyl‐5‐methoxyoxazole
Authors: Bondock Samir
Published: January 2005

A novel series of pyridine derivatives with anticipated biological activity have been synthesized via Diels‐Alder reactions of 2,4‐dimethyl‐5‐methoxyoxazole with different types of dienophiles. The regioselectivity of the cycloaddition was inverted from methylacrylate to tert‐butylacrylate. The structural elucidation of the new compounds was carried on the basis of spectral and X‐ray analyses. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:49–55, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20064
Facile synthesis of 2‐alkylthio‐3‐amino‐4 H‐imidazol‐4‐ones and 2H‐imidazo[2,1‐b]‐1,3,4‐thiadiazin‐6(7H)‐ones via N‐vinylic iminophosphorane
Authors: Ding Ming‐Wu , Fu Bo‐Qiao , Yuan Ju‐Zhen
Published: January 2005

2‐Alkylthio‐3‐amino‐4H‐imidazol‐4‐ ones 5 were synthesized by S‐alkylation of 2‐thioxo‐3‐amino‐4‐imidazolidinones 4, which were obtained via cyclization of isothiocyanates 2 with hydrazine hydrate. 5l–n reacted with Ph3P, C2Cl6, and NEt3 to give 2H‐imidazo[2,1‐b]‐1,3,4‐thiadiazin‐ 6(7H)‐ones 7a–c in good yields. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:76–80, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20069
Reactions of 2‐amino‐3‐cyano‐4,5,6,7‐tetrahydrobenzo[b]thiophene and 2‐amino‐3‐cyano‐4,7‐diphenyl‐5‐methyl‐4H‐pyrano[2,3‐c] pyrazole with phenylisocyanate, carbon disulfide, and thiourea
Authors: Youssef Ahmed S. A. , Kandeel Kamal A. , Fouli Fouli A. , Abou‐Elmagd Wael S. I.
Published: January 2005

2‐Amino‐3‐cyano‐4,5,6,7‐tetrahydrobenzo[b]thiophene 1a or 2‐amino‐3‐cyano‐4,7‐di‐ phenyl‐5‐methyl‐4H‐pyrano[2,3‐c]pyrazole 2a reacted with phenylisocyanate in dry pyridine to give 2‐(3‐phenylureido)‐3‐cyanobenzo[b]thiophene 1b or 2‐disubstituted amino‐3‐cyanopyranopyrazole 2b derivative. However, when 1a and 2a were refluxed with carbon disulfide in 10% ethanolic sodium hydroxide solution, they afforded the thieno[2,3‐d]pyrimidin‐2,4‐dithione derivative 5 in the former case, 2,4‐dicyano‐1,3‐bis(dithio carboxamino)cyclobuta‐1,3‐ diene 6 and pyrazolopyranopyrido[2,3‐d]pyrimidin‐ 2,4‐dithione derivative 7 in the latter one. Treatment of 2a with thiourea in refluxing ethanol in the presence of potassium carbonate gave 2,2′‐dithiobispyrimidine derivative 9 (major) in addition to pyranopyrazole derivative 10 and 2,2′‐dithiobis ethoxypyrimidine derivative 11 in minor amounts. The structures of all products were evidenced by microanalytical and spectral data. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:6–11, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20070
Using the 1,2‐dihydro‐1,2‐diphosphinine ring as a template for the synthesis of new bicyclic structures and new trans‐chelating bis‐phosphines
Authors: Huy Ngoc Hoa Tran , Chaigne Pauline , Déchamps Ingrid , Ricard Louis , Mathey François
Published: January 2005

The 1,2‐dihydro‐1,2‐diphosphinine decacarbonylditungsten complex 1 has been used as a synthetic equivalent of the corresponding 1,2‐dianion 2. These two 1,2‐positions can be linked by a (CH2)4 bridge to yield a [4.4.0] bicyclic structure 6 whose identity has been confirmed by X‐ray crystal structure analysis. Alternatively, two ω‐iodohexyl chains can be grafted onto these positions and the resulting diiodo derivative 9 transformed into a long‐chain bis‐phosphine 10 by reaction with lithium diphenylphosphide. This bis‐phosphine gives a chelate complex with PdCl2 whose trans‐stereochemistry was established by X‐ray crystal structure analysis. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:44–48, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20073
Achieving data compatibility over space and time: creating consistent geographical zones
Authors: Norman Paul , Rees Philip , Boyle Paul
Published: January 2005

The importance of boundary specification and problems with using arbitrarily defined subnational areas for the collection and dissemination of socioeconomic data are widely recognised. Much research has focused on the modifiable areal unit problem and on custom zone design, but the practical difficulties created by temporal inconsistencies in zonal boundaries have received less consideration. The UK experiences frequent administrative boundary changes causing difficulties in producing comparable statistics through time. Unless a consistent geographical approach is taken with time‐series data, it cannot be known whether changes in the relationships between variables collected for areas at different points in time are real or an artefact of boundary changes. After illustrating the nature of the boundary change problems to be overcome, this paper appraises strategies that can be adopted and develops a method by which time‐series data can be established on a consistent geographical basis. Copyright © 2003 John Wiley & Sons, Ltd.
Who is the counter‐urban mover? Evidence from the Swedish urban system
Authors: Lindgren Urban
Published: January 2005

This study analyses differences between counter‐urban movers and movers heading for other destinations. Through the elaboration of a spatial model based upon settlement structure and functional hinterlands, counter‐urban migration can be measured on the ground throughout the urban system. Empirical analysis of the counter‐urban mover is rendered possible by access to a comprehensive longitudinal micro‐database that contains demographic, socio‐economic and detailed geographic information for all Swedish citizens. Binomial and multinomial logit models are estimated to capture the partial effects of variables related to the individual, the household, the labour market, life course events, and regional economic conditions on the choice of migration destination. The results of the analyses show that counter‐urban movers are more likely to be older, born in Sweden or any other Scandinavian country, less well‐off, having a university qualification, living single, being outside the labour force, and becoming unemployed close to the migration event. The emerging picture of the Swedish counter‐urban mover reveals an individual who may be striving for other qualities in life, where career and earnings are of minor importance. Somewhat unexpectedly, the counter‐urban movers show no systematic differences depending on their place of departure. No clear hierarchy‐specific effects across the urban system can be found. Copyright © 2003 John Wiley & Sons, Ltd.
A comparison of migration behaviour in Japan and Britain using spatial interaction models
Authors: Yano Keiji , Nakaya Tomoki , Fotheringham A. Stewart , Openshaw Stan , Ishikawa Yoshitaka
Published: January 2005

Several recent papers have compared the measurement of migration in different countries, and some have compared migration patterns to the extent that these can be compared cross‐nationally. In this paper we measure and comment on differences in the behaviour of migrants in two systems, Japan and Britain. In both countries the focus of attention is on interregional migration. Migration behaviour is measured in terms of elasticities of migration responses to various aspects of destination attractiveness, namely distance from the origin, population size and relative accessibility to other destinations. Origin‐specific migration destination choice models are calibrated to obtain this information. The results reveal interesting differences in the factors underlying destination attractiveness in the two countries which have important implications both for the way in which migration is modelled, and for the impacts of migration on the urban systems in both countries. Copyright © 2003 John Wiley & Sons, Ltd.
Mechanical performance and osteoblast‐like cell responses of fluorine‐substituted hydroxyapatite and zirconia dense composite
Authors: Kim Hae‐Won , Knowles Jonathan C. , Li Long‐Hao , Kim Hyoun‐Ee
Published: January 2005

A fluorine‐substituted hydroxyapatite (FHA) and zirconia (ZrO2) dense composite (50:50 by volume) was fabricated, and its feasibility for hard tissue applications was investigated in terms of its mechanical properties and osteoblast‐like cell (MG63) responses in vitro. The incorporation of fluorine into the hydroxyapatite (HA) structure was highly effective in producing a completely dense apatite–ZrO2 composite through a pressureless sintering route, by preventing the thermal degradation of the apatite and ZrO2. The resultant FHA–ZrO2 dense composite had excellent mechanical properties, such as flexural strength (310 MPa), fracture toughness (3.4 MPam1/2), hardness (10 GPa), and elastic modulus (160 GPa). The flexural strength and fracture toughness of the composite showed a noticeable improvement by a factor of ∼4 with respect to the pure apatites (HA and FHA). The MG63 cellular responses to the composite were assessed in terms of the cell proliferation (cell number and [3H]‐thymidine incorporation) and differentiation (alkaline phosphatase activity, osteocalcin, and collagen production). The cells on the FHA–ZrO2 composite spread and grew well, and proliferated actively during the culture period. The expression of alkaline phosphatase, osteocalcin, and collagen by the cells on the composite showed a similar trend to that on the pure apatites, although slight down‐regulations were observed, implying that the FHA–ZrO2 50:50 composite retains the osteoblastic functionality and traits of the pure HA ceramics to a high degree. This finding, in conjunction with the considerable improvements in mechanical properties, supports the extended use of this composite for hard tissue applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 258–268, 2005
Temporal effects of a COX‐2‐selective NSAID on bone ingrowth
Authors: Goodman Stuart B. , Ma Ting , Mitsunaga Lance , Miyanishi Keita , Genovese Mark C. , Smith R. Lane
Published: January 2005

The effects of a short course of a COX‐2 inhibitor on bone healing when the drug is discontinued are unknown. We examined the effects of rofecoxib on bone ingrowth over a 6‐week period using a well‐defined animal model. The Bone Harvest Chamber was implanted bilaterally in mature rabbits. After osseointegration of the chamber, the following treatments were given for 6 weeks each, followed by a harvest in each case: control‐no drug; oral rofecoxib (12.5 mg/day) for the first 2 of 6 weeks; washout period‐no drug; oral rofecoxib for the last 2 of 6 weeks; washout period‐no drug; rofecoxib given continuously for all 6 weeks. Harvested specimens were snap‐frozen, cut into serial 6‐μm sections, and stained with hematoxylin and eosin and alkaline phosphatase (osteoblast marker), and processed using immunohistochemistry to identify the vitronectin receptor (osteoclast‐like cells). Rofecoxib given continuously for 6 weeks yielded statistically less bone ingrowth compared to the control treatment. Rofecoxib given during the initial or final 2 weeks of a 6‐week treatment did not appear to interfere with bone ingrowth. This suggests that the effects of COX‐2 inhibitors on bone are less profound when the drug is administered for a short period of time. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 279–287, 2005
Cellular evaluation of oral chemotherapy carriers
Authors: Blanchette James , Peppas Nicholas A.
Published: January 2005

Hydrogel nanospheres composed of methacrylic acid and poly(ethylene glycol) were loaded with bleomycin and tested as a potential oral delivery system for chemotherapeutic agents. The gastrointestinal epithelium was modeled through the use of Caco‐2 monolayers for studies of permeation enhancement by the carriers as well as bleomycin transport. Bleomycin efficacy following release from the carrier was evaluated with a DLD‐1 tumor cell model. The nanospheres release bleomycin in response to a pH increase similar to that seen when passing from the stomach into the upper small intestine. These carriers can also increase the permeability of a model of the epithelial barrier, which would hopefully improve drug transport into the bloodstream. Efficacy studies using a tumor cell model showed retention of activity for bleomycin following loading and release from the nanospheres. The carriers described performed well during in vitro evaluation and can hopefully expand the spectrum of chemotherapeutic agents capable of being administered orally. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 381–388, 2005
Adherent apatite coating on titanium substrate using chemical deposition
Authors: Rohanizadeh R. , LeGeros R.Z. , Harsono M. , Bendavid A.
Published: January 2005

Plasma‐sprayed “HA” coatings on commercial orthopedic and dental implants consist of mixtures of calcium phosphate phases, predominantly a crystalline calcium phosphate phase, hydroxyapatite (HA) and an amorphous calcium phosphate (ACP) with varying HA/ACP ratios. Alternatives to the plasma‐spray method are being explored because of some of its disadvantages. The purpose of this study was to deposit an adherent apatite coating on titanium substrate using a two‐step method. First, titanium substrates were immersed in acidic solution of calcium phosphate resulting in the deposition of a monetite (CaHPO4) coating. Second, the monetite crystals were transformed to apatite by hydrolysis in NaOH solution. Composition and morphology of the initial and final coatings were identified using X‐ray diffraction (XRD), Scanning Electron Microscopy, and Energy Dispersive Spectroscopy (EDS). The final coating was porous and the apatite crystals were agglomerated and followed the outline of the large monetite crystals. EDS revealed the presence of calcium and phosphorous elements on the titanium substrate after removing the coating using tensile or scratching tests. The average tensile bond of the coating was 5.2 MPa and cohesion failures were observed more frequently than adhesion failures. The coating adhesion measured using scratch test with a 200‐μm‐radius stylus was 13.1N. Images from the scratch tracks demonstrated that the coating materials were squashed without fracturing inside and/or at the border of the tracks until the failure point of the coating. In conclusion, this study showed the potential of a chemical deposition method for depositing a coating consisting of either monetite or apatite. This method has the advantage of producing a coating with homogenous composition on even implants of complex geometry or porosity. This method involves low temperatures and, therefore, can allow the incorporation of growth factors or biogenic molecules. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 428–438, 2005
Assessment of left ventricular function by breath‐hold cine MR imaging: Comparison of different steady‐state free precession sequences
Authors: Kunz R. Peter , Oellig Florian , Krummenauer Frank , Oberholzer Katja , Romaneehsen Bernd , Vomweg Toni W. , Horstick Georg , Hayes Carmel , Thelen Manfred , Kreitner Karl‐Friedrich
Published: January 2005

Purpose

To compare steady‐state free precession (SSFP) sequence protocols with different acquisition times (TA) and temporal resolutions (tRes) due to the implementation of a view sharing technique called shared phases for the assessment of left ventricular (LV) function by breath‐hold cine magnetic resonance (MR) imaging.

Materials and Methods

End‐diastolic and end‐systolic volumes (EDV, ESV) were measured in contiguous short‐axis slices with a thickness of 8 mm acquired in 10 healthy male volunteers. The following true fast imaging with steady‐state precession (TrueFISP) sequence protocols were compared: protocol A) internal standard of reference, segmented: tRes 34.5 msec, TA 18 beats per slice; protocol B) segmented, shared phases: tRes 34.1 msec, TA 10 beats per slice; and protocol C) real‐time, shared phases, parallel acquisition technique: tRes 47.3 msec, TA 24 beats for 12 slices covering the entire left ventricle.

Results

Phase sharing leads to a significant decrease in EDV, stroke volume (SV), and ejection fraction (EF) (median difference −7.0 mL [*], −9.6 mL, and −3.4%, respectively, for protocol B; −15.3 mL, −13.3 mL, and −2.4% for protocol C; P = 0.002, *P = 0.021). The observed median difference of real‐time EDV and SV estimates is of clinical relevance. Real‐time cine MR imaging shows a greater variability of EDV and SV. No relevant differences in ESV were observed.

Conclusion

The true cine frame duration of both shared phases sequence protocols exceeds the period of isovolumetric contraction (IVCT) of the left ventricle resulting in a systematic and significant underestimation of EDV and consequently SV and EF. SSFP sequence protocol par‐ameters, particularly tRes and use of view sharing techniques, should therefore be known at follow‐up examinations in order to be able to assess LV remodeling in patients with heart failure. J. Magn. Reson. Imaging 2005;21:140–148. © 2005 Wiley‐Liss, Inc.
The role of edema and demyelination in chronic T1 black holes: A quantitative magnetization transfer study
Authors: Levesque Ives , Sled John G. , Narayanan Sridar , Santos A. Carlos , Brass Steven D. , Francis Simon J. , Arnold Douglas L. , Pike G. Bruce
Published: January 2005

Purpose

To use quantitative magnetization transfer imaging (qMTI) in an investigation of T1‐weighted hypointensity observed in clinical magnetic resonance imaging (MRI) scans of multiple sclerosis (MS) patients, which has previously been proposed as a more specific indicator of tissue damage than the more commonly detected T2 hyperintensity.

Materials and Methods

A cross‐sectional study of 10 MS patients was performed using qMTI. A total of 60 MTI measurements were collected in each patient at a resolution of 2 × 2 × 7 mm, over a range of saturation pulses. The observed T1 and T2 were also measured. qMT model parameters were estimated using a voxel‐by‐voxel fit.

Results

A total of 65 T2‐hyperintense lesions were identified; 53 were also T1 hypointense. In these black holes, the qMTI‐derived semisolid pool fraction F correlated negatively with T1,obs (r2 = 0.76; P < 0.0001). The water pool absolute size (PDf) showed a weaker correlation with T1,obs (positive, r2 = 0.53; P < 0.0001). The magnetization transfer ratio (MTR) showed a similarly strong correlation with F and a weaker correlation with PDf (r2 = 0.18; P < 0.04).

Conclusion

T1 increases in chronic black holes strongly correlated with the decline in semisolid pool size, and somewhat less to the confounding effect of edema. MTR was less sensitive than T1,obs to liquid pool changes associated with edema. J. Magn. Reson. Imaging 2005;21:103–110. © 2005 Wiley‐Liss, Inc.
Coronary artery wall imaging: Initial experience at 3 Tesla
Authors: Koktzoglou Ioannis , Simonetti Orlando , Li Debiao
Published: January 2005

Purpose

To assess the feasibility of black‐blood turbo spin‐echo imaging of the left anterior descending coronary artery wall at 3 Tesla under free‐breathing and breath‐hold conditions.

Materials and Methods

Proton density‐weighted black‐blood turbo spin‐echo imaging of the left anterior descending coronary artery was performed on 15 volunteers on a 3 T whole body scanner with an eight channel phased array coil. Volunteers were imaged during free‐breathing (with navigators, N = 5), or with breath‐hold (N = 5), or both (N = 2). Imaging was not possible in three volunteers due to either gradient or radiofrequency (RF) coupling with the electrocardiogram (ECG). Images were analyzed to determine coronary artery wall thickness, wall area, lumen diameter, and lumen area. Signal‐to‐noise and contrast‐to‐noise ratios were calculated.

Results

Coronary artery wall thickness, wall area, lumen diameter, and lumen area measurements were consistent with previous magnetic resonance (MR) measurements of the coronary wall at 1.5 Tesla.

Conclusion

Coronary wall imaging using free‐breathing and breath‐hold two‐dimensional black‐blood TSE is feasible at 3 T. Further improvement in resolution and image quality is required to detect and characterize coronary plaque. J. Magn. Reson. Imaging 2005;21:128–132. © 2005 Wiley‐Liss, Inc.
MR imaging of the normal appendix and acute appendicitis
Authors: Nitta Norihisa , Takahashi Masashi , Furukawa Akira , Murata Kiyoshi , Mori Masayuki , Fukushima Masanobu
Published: January 2005

Purpose

To describe the MR appearance of the normal appendix and the MR imaging characteristics of acute appendicitis with correlation to pathological severity.

Materials and Methods

A total of 20 volunteers participated in this study to demonstrate normal appendices by MR imaging. A total of 37 consecutive patients with clinically diagnosed acute appendicitis were also scanned. T1‐weighted (T1WI) spin‐echo images, T2‐weighted (T2WI) fast spin‐echo, and fat‐suppressed spectral presaturation inversion recovery T2‐weighted (T2SPIR) fast spin‐echo images were obtained. The MR criteria for considering acute appendicitis were as follows: 1) thickening of the appendiceal wall with high intensity on T2WI or T2SPIR; 2) dilated lumen filled with high intensity material on T2WI or T2SPIR; and 3) increased intensity of periappendiceal tissue on T2WI or T2SPIR.

Results

The visibility of a normal appendix on MR imaging was 90% (18/20). It appeared as a cord‐like structure of medium intensity without fluid collection in the lumen. A total of 30 cases with clinically diagnosed acute appendicitis had positive MR findings and all except one were pathologically proven. The one had cecal diverticulitis. These cases demonstrated filled lumen, with a hypointense wall on T1WI and slightly hyperintense on T2WI or T2SPIR. MR findings correlated well with pathological severity, especially a thicker wall, periappendiceal high intensity, and ascites were useful for suspecting severe appendicitis.

Conclusion

Correct diagnosis of acute appendicitis was obtained with MRI, and correlated well with its pathological severity. MRI is a powerful alternative for diagnosing acute appendicitis especially for the patients in whom the radiation is major concern. J. Magn. Reson. Imaging 2005;21:156–165. © 2005 Wiley‐Liss, Inc.
Myometrial invasion and cervical invasion by endometrial carcinoma: Evaluation by CO2‐volumetric interpolated breathhold examination (VIBE)
Authors: Akaeda Tomoyoshi , Isaka Keiichi , Takayama Masaomi , Kakizaki Dai , Abe Kimihiko
Published: January 2005

Purpose

To assess myometrial invasion and cervical invasion by endometrial carcinoma, using CO2‐volumetric interpolated breathhold examination (VIBE) enabling more precise evaluation of depth of tumor invasion.

Materials and Methods

CO2‐VIBE was performed in 21 cases of endometrial carcinoma (Stage Ia–IIb) prior to treatment. The images were interpreted by performing multiplanar reconstruction (MPR), and the findings obtained from the images (degree of myometrial invasion and presence or absence of cervical invasion) were assessed in comparison with the histopathological diagnosis.

Results

The sites of the endometrial carcinoma lesions were clearly visualized by the CO2‐VIBE method. Evaluation of the degree of myometrial invasion enabled a high correct diagnosis rate of 90.5%, and evaluation for the presence of cervical invasion also allowed a high correct diagnosis rate of 90.5%.

Conclusion

VIBE permits evaluation of any plane desired by means of thin slices, and it is a truly revolutionary method for preoperative evaluation of depth of invasion of endometrial carcinoma that enables highly accurate determination of the extent of lesion sites and degree of invasion before treatment. J. Magn. Reson. Imaging 2005;21:166–171. © 2005 Wiley‐Liss, Inc.