bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical bonding in view of electron charge density and kinetic energy density descriptors
Authors: Jacobsen Heiko
Published: December 2008

Stalke's dilemma, stating that different chemical interpretations are obtained when one and the same density is interpreted either by means of natural bond orbital (NBO) and subsequent natural resonance theory (NRT) application or by the quantum theory of atoms in molecules (QTAIM), is reinvestigated. It is shown that within the framework of QTAIM, the question as to whether for a given molecule two atoms are bonded or not is only meaningful in the context of a well‐defined reference geometry. The localized‐orbital‐locator (LOL) is applied to map out patterns in covalent bonding interaction, and produces results that are consistent for a variety of reference geometries. Furthermore, LOL interpretations are in accord with NBO/NRT, and assist in an interpretation in terms of covalent bonding. © 2008 Wiley Periodicals, Inc.J Comput Chem, 2009.
Reaction mechanism of palladium‐catalyzed silastannation of allenes by density functional theory
Authors: Wang Meiyan , Cheng Lin , Hong Bo , Wu Zhijian
Published: December 2008

The reaction mechanism of Pd(0)‐catalyzed allenes silastannation reaction is investigated by the density functional method B3LYP. The overall reaction mechanism is examined. For the allene insertion step, the PdSi bond is preferred over the PdSn bond. The electronic mechanism of the allene insertion into PdSi bond to form σ‐vinylpalladium (terminal‐insertion) and σ‐allylpalladium (internal‐insertion) insertion products is discussed in terms of the electron donation and back‐donation. It is found that the electron back‐donation is significant for both terminal‐ and internal‐insertion. During allene insertion into PdSi bond, internal‐insertion is preferred over terminal‐insertion. By using methylallene, the regio‐selectivity for the monosubstituted allene insertion into PdSi and PdSn bond is analyzed. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009
Conceptual DFT properties‐based 3D QSAR: Analysis of inhibitors of the nicotine metabolizing CYP2A6 enzyme
Authors: Van Damme Sofie , Bultinck Patrick
Published: December 2008

Structure‐activity relationships of 46 P450 2A6 inhibitors were analyzed using the 3D‐QSAR methodology. The analysis was carried out to confront the use of traditional steric and electrostatic fields with that of a number of fields reflecting conceptual DFT properties: electron density, HOMO, LUMO, and Fukuif−function as 3D fields. The most predictive models were obtained by combining the information of the electron density with the Fukuif−function (r2= 0.82,q2= 0.72), yielding a statistically significant and predictive model. The generated model was able to predict the inhibition potencies of an external test set of five chemicals. The result of the analysis indicates that conceptual DFT‐based molecular fields can be useful as 3D QSAR molecular interaction fields. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009
First‐principles calculations of the stability and electronic properties of the PbTiO3 (110) polar surface
Authors: Zhang Guo‐Xu , Xie Ying , Yu Hai‐Tao , Fu Hong‐Gang
Published: December 2008

The structural and electronic properties of five terminations of cubic lead titanate (PbTiO3) (110) polar surface were investigated by first‐principles total‐energy calculations using a periodic slab model. On the PbTiO termination, an anomalous filling of conduction band was observed, whereas on the O2 termination, two surface oxygen atoms formed a peroxo group, demonstrating that the electronic structures of the two stoichiometric terminations undergo significant changes with respect to bulk materials. However, for the three nonstoichiometric TiO‐, Pb‐, and O‐terminated surfaces, their electronic structures are very similar to bulk. Charge redistribution results for the five terminations confirmed that electronic structure and surface composition changes are responsible for their polarity compensation. However, which mechanism actually dominates the stabilization process depends upon energetic considerations. A thermodynamic stability diagram suggested that the two stoichiometric terminations are unstable; however, the three nonstoichiometric terminations can be stabilized in some given regions. Furthermore, this study indicates that the very different stabilities and surface states filling behaviors of the PbTiO3 (110) polar surface with respect to SrTiO3 and BaTiO3 ones seem to originate from the partially covalent characteristics of PbO pairs. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009
Numerical examination of the extended phase‐space volume‐preserving integrator by the Nosé‐Hoover molecular dynamics equations
Authors: Queyroy Séverine , Nakamura Haruki , Fukuda Ikuo
Published: December 2008

This article illustrates practical applications to molecular dynamics simulations of the recently developed numerical integrators [Phys Rev E 2006, 73, 026703] for ordinary differential equations. This method consists of extending any set of ordinary differential equations in order to define a time invariant function, and then use the techniques of divergence‐free solvable decomposition and symmetric composition to obtain volume‐preserving integrators in the extended phase space. Here, we have developed the technique by constructing multiple extended‐variable formalism in order to enhance the handling in actual simulation, and by constituting higher order integrators to obtain further accuracies. Using these integrators, we perform constant temperature molecular dynamics simulations of liquid water, liquid argon and peptide in liquid water droplet. The temperature control is obtained through an extended version of the Nosé‐Hoover equations. Analyzing the effects of the simulation conditions including time step length, initial values, boundary conditions, and equation parameters, we investigate local accuracy, global accuracy, computational cost, and sensitivity along with the sampling validity. According to the results of these simulations, we show that the volume‐preserving integrators developed by the current method are more effective than traditional integrators that lack the volume‐preserving property. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009
Multiple Markov transition matrix method: Obtaining the stationary probability distribution from multiple simulations
Authors: Sakuraba Shun , Kitao Akio
Published: December 2008

We herein propose the multiple Markov transition matrix method (MMMM), an algorithm by which to estimate the stationary probability distribution from independent multiple molecular dynamics simulations with different Hamiltonians. Applications to the potential of mean force calculation in combination with the umbrella sampling method are presented. First, the performance of the MMMM is examined in the case of butane. Compared with the weighted histogram analysis method (WHAM), the MMMM has an advantage with respect to the reasonable evaluation of the stationary probability distribution even from nonequilibrium trajectories. This method is then applied to Met‐enkephalin nonequilibrium simulation. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009
Overexpression of ΔNp63 in a human nasopharyngeal carcinoma cell line downregulates CKIs and enhances cell proliferation
Authors: Chiang Chi‐Tai , Chu Wing‐Keung , Chow Shu‐Er , Chen Jan‐Kan
Published: December 2008

p63 belongs to a member of the tumor suppressor protein p53 family. Due to alternative promoter usage, two types of p63 proteins are produced. The ΔNp63 isoform lacks the N‐terminal transactivation domain and is thought to antagonize TAp63 and p53 in target gene regulation. ΔNp63 has been found to be overexpressed in numerous human squamous cell carcinomas, including nasopharyngeal carcinoma (NPC). However, the role of ΔNp63 overexpression in NPC pathogenesis has not been clear. In this study, we use a ΔNp63 overexpressing human NPC cell line (NPC‐076) to explore the possible roles of ΔNp63 in cell proliferation and cell‐cycle regulation. We found that the proliferation of NPC‐076 cell is greatly suppressed when the overexpressed ΔNp63 is silenced by specific ΔNp63 siRNA. Further studies show that ΔNp63 silencing results in the upregulation of CKIs, including p27kip1 and p57kip2 in both mRNA and protein levels. Cell‐cycle analysis shows that ΔNp63 silencing also results in an increased G1 phase cell and apoptotic cell population. Our findings indicate that ΔNp63 plays important roles in the regulation of NPC‐076 cell‐cycle progression, and may play a role in the maintenance of NPC‐076 tumor cell phenotype. J. Cell. Physiol. 219: 117–122, 2009. © 2008 Wiley‐Liss, Inc.
A novel role of ERK5 in integrin‐mediated cell adhesion and motility in cancer cells via Fak signaling
Authors: Sawhney Rajinder S. , Liu Wensheng , Brattain Michael G.
Published: December 2008

In metastatic cancer, high expression levels of vitronectin (VN) receptors (integrins), FAK, and ERK5 are reported. We hypothesized that integrin‐mediated ERK5 activation via FAK may play a pivotal role in cell adhesion, motility, and metastasis. ERK5 and FAK phosphorylation when metastatic MDA‐MB‐231 and PC‐3 cells were plated on VN was enhanced. Further experiments showed co‐immunoprecipitation of integrins β1, αVβ3, or αVβ5 with ERK5 and FAK. To gain better insight into the mechanism of ERK5, FAK, and VN receptors in cell adhesion and motility, we performed loss‐of‐function experiments using integrin blocking antibodies, and specific mutants of FAK and ERK5. Ectopic expression of dominant negative ERK5/AEF decreased ERK5 and FAK (Y397) phosphorylation, cell adhesion, and haptotactic motility (micromotion) on VN. Additionally, DN FAK expression attenuated ERK5 phosphorylation, cell adhesion, and motility. This study documents the novel finding that in breast and prostate cancer cells, ERK5 is a critical target of FAK in cell adhesion signaling. Using different cancer cells, our experiments unveil a novel mechanism by which VN receptors and FAK could promote cancer metastasis via ERK5 activation. J. Cell. Physiol. 219: 152–161, 2009. © 2008 Wiley‐Liss, Inc.
Molecular genetics of ameloblast cell lineage
Authors: Bei Marianna
Published: December 2008

Late tooth morphogenesis is characterized by a series of events that determine crown morphogenesis and the histodifferentiation of epithelial cells into enamel‐secreting ameloblasts and of mesenchymal cells into dentin‐secreting odontoblasts. Functional ameloblasts are tall, columnar, polarized cells that synthesize and secrete a number of enamel‐specific proteins. After depositing the full thickness of enamel matrix, ameloblasts shrink in size and regulate enamel maturation. Amelogenesis imperfecta (AI) is a heterogeneous group of inherited defects in enamel formation. Clinically, AI presents as a spectrum of enamel malformations that are categorized as hypoplastic, hypocalcified, or hypomaturation types, based upon the thickness and hardness of the enamel. The different types of AI are inherited, either as X‐linked, autosomal‐dominant, or autosomal‐recessive traits. Recently, several gene mutations have been identified to cause the subtypes of AI. How these genes, however, coordinate their function to control amelogenesis is not understood. In this review, we discuss the role of genes that play definitive role on the determination of ameloblast cell fate and life cycle based on studies in transgenic animals. J. Exp. Zool. (Mol. Dev. Evol.) 312B:437–444, 2009. © 2008 Wiley‐Liss, Inc.
Positional dependence of FDTD mode detection in photonic crystal systems
Authors: Stark G. A. , Mishrikey M. , Robin F. , Jaeckel H. , Hafner C. , Vahldieck R. , Erni D.
Published: December 2008

We have developed an algorithm for evaluating the accuracy and reliability of photonic crystal (PhC) simulations, and used it to analyze the influence of excitation and detector placement in finite‐difference time‐domain algorithm (FDTD) simulations of two canonical PhC systems. In order to perform this computationally expensive analysis, we evaluated the use of filter diagonalization as an alternative to the Fourier Transform for mode detection, and developed a parallelization algorithm to take advantage of the inherent concurrency in simulating periodic systems. A map of locations where mode detection fails was generated, and we show that this is equivalent to a map of the node densities of the system. In addition to the expected high nodal densities at the symmetry areas of each system, we find more difficult to characterize patterns of high nodal density for the higher‐order modes. Based on the observed behavior we are able to provide concrete rules to optimize the detection and excitation of modes in FDTD simulations of PhC systems. Although PhCs were studied, the presented strategies and results apply to the much broader class of all computational time‐domain problems where Bloch–Floquet boundary conditions are used. Copyright © 2008 John Wiley & Sons, Ltd.
Halide‐ion‐assisted increase of surface‐enhanced hyper‐Raman scattering: a clear observation of the chemical effect
Authors: Palonpon Almar , Ichimura Taro , Verma Prabhat , Inouye Yasushi , Kawata Satoshi
Published: December 2008

We show that the increase of surface‐enhanced hyper‐Raman scattering (SEHRS) intensity of organic dye molecules adsorbed on single silver (Ag) colloid aggregate in the presence of halide ions is a direct evidence of the chemical effect in the enhancement mechanism. Time‐dependent SEHRS measurements before and after adding halide ions enabled us to distinctly observe the chemical effect. The presence of the halide ions results to a more stable chemical interaction between metal and dye molecule, making it more resistant against photodegradation effects. This study can contribute in elucidating the chemical effect mechanism and aid in the development of SEHRS as a useful spectroscopic tool. Copyright © 2008 John Wiley & Sons, Ltd.
Evaluating the guest experience at theme parks: an empirical investigation of key attributes
Authors: Milman Ady
Published: December 2008

The study identified and documented a consumer‐oriented attribute inventory for evaluating theme parks. Data were collected from 608 Central Florida residents, domestic and international tourists who identified and ranked the level of importance of 41 attributes and park characteristics when visiting a typical theme park. Further analysis of the data using factor analysis identified seven key constructs that summarised important areas of concern when consumers evaluate theme parks. The majority of these factors were related to guest experiences such as (i) entertainment variety and quality; (ii) courtesy, cleanliness, safety and security; (iii) food variety and value for money; (iv) quality of theming and design; (v) availability and variety of family‐oriented activities; (vi) quality and variety of rides and attractions; and (vii) pricing and value for money. Implications for theme park owners, operators and marketing executives were discussed in light of the increasing demand for distinctive guest experiences while visiting theme parks. Copyright © 2008 John Wiley & Sons, Ltd.
Structure and Properties of Mono‐, Di‐, Tri‐ and Multiblock Segmented Copolymers with Diamide Hard Segments
Authors: Arun Araichimani , Dullaert Konraad , Gaymans Reinoud J.
Published: December 2008

Well‐defined segmented block copolymers were studied as the number and position of hard segments in the chain was varied. The hard segments were diamides of uniform length (A), and the synthesized copolymers were mono‐, di‐, tri‐ or multiblock using the soft segment (B), poly(tetramethylene oxide), with a molecular weight of 2 900 g mol−1 and extended with terephthalate groups to reach a maximum of 20 000 g mol−1. The diamide segments in the chain displayed very high crystallinities and a ribbon‐like structure with high aspect ratio. The copolymer without hard segments was a semi‐solid. For the materials with one diamide unit in the chain, the modulus was high but the yield and fracture strengths low. When two or more diamide units were used, both the modulus and values for the yield and fracture strengths were high.

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Macromol. Chem. Phys. 24/2008
Authors: Papagiannopoulos Aristeidis , Fernyhough Christine M. , Waigh Thomas A. , Radulescu Aurel
Published: December 2008

Cover: The structure of charged flexible comb polymers is examined in solution. High resolution probes based on light, X‐rays, and neutrons are used, providing information on nanometer to hundreds of nanometer length scale morphologies. Scaling models are developed for the chain conformation for isolated (dilute) and overlapping (semidilute) combs. Further details can be found in the article by A. Papagiannopoulos, C. M. Fernyhough, T. A. Waigh* and A. Radulescu, on page 2475.
Fluorescence Investigations of Oxygen‐Doped Simple Amine Compared with Fluorescent PAMAM Dendrimer
Authors: Chu Chih‐Chien , Imae Toyoko
Published: December 2008

Blue emission of oxygen‐doped tertiary amine (triethylamine), a key unit of fluorescent poly(amido amine) dendrimer, was demonstrated. It was found that the fluorescence intensity could be further enhanced if the tertiary amines locate densely in the dendrimer interior as the branching sites. Moreover, a solvatochromic phenol blue, instead of oxygen, is able to induce the blue fluorescence of the tertiary amino‐branching sites based on a guaranteed host‐guest complexation of phenol blue molecules and dendrimer interior.

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Co‐Continuous Polymeric Nanostructures via Simple Melt Mixing of PS/PMMA
Authors: Pu Gongwei , Luo Yingwu , Lou Qianchuan , Li Bogeng
Published: December 2008

Blends of polystyrene/poly(methyl methacrylate) (PS/PMMA) (30/70) prepared by simple melt mixing form a droplet (PS) in‐matrix (PMMA) morphology. It is found that addition of a carefully designed copolymer PS‐b‐P(S‐ran‐MMA) (SSM) compatibilizer could convert the morphology into a co‐continuous system. Indeed, the continuity of the dispersed PS phase increased with an increase in PS‐b‐P(S‐ran‐MMA) content, and a fully co‐continuous morphology (continuity = 100%) was obtained at 20% SSM fraction with a characteristic size of 100 nm.

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Cross‐Linking and Degradation Properties of Plasma Enhanced Chemical Vapor Deposited Poly(2‐hydroxyethyl methacrylate)
Authors: Pfluger Courtney A. , Carrier Rebecca L. , Sun Bing , Ziemer Katherine S. , Burkey Daniel D.
Published: December 2008

Plasma Enhanced Chemical Vapor Deposition (PECVD) of poly‐2‐hydroxyethyl methacrylate (pHEMA) biocompatible, biodegradable polymer films were produced alone and cross‐linked with ethylene glycol diacrylate (EGDA). Degree of cross‐linking was controlled via manipulation of the EGDA flow rate, which influenced the amount of swelling and the extent of degradation of the films in an aqueous solution over time. Noncross‐linked pHEMA films swelled 10% more than cross‐linked films after 24 h of incubation in an aqueous environment. Increasing degree of film cross‐linking decreased degradation over time. Thus, PECVD pHEMA films with variable cross‐linking properties enable tuning of gel formation and degradation properties, making these films useful in a variety of biologically significant applications.

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FEM analysis of localized deformation behaviour in pseudoelastic NiTi shape memory alloys
Authors: Wang X.M. , Lu Z.Z. , Yue Z.F. , Deng C.H.
Published: December 2008

This paper takes into account the localized deformation behaviour of a pseudoelastic NiTi shape memory alloy with finite element method. A three‐dimensional micromechanical model has been developed, in which the difference between the elastic properties of austenite and martensite is considered. The model is implemented as User MATerial subroutine (UMAT) into ABAQUS. Then, a polycrystalline NiTi shape memory alloy with [1 1 1] texture under tensile loading is simulated. The main features of the propagation of the deformation band reported in literatures are captured in the simulation. It is also shown that the initiation and propagation of the deformation bands are strongly affected by the geometry of the specimens.
Entwicklung des Reibnietens als neues Fügeverfahren für Kunststoff und Leichtbaulegierungen
Authors: Amancio‐Filho S. T. , dos Santos J. F.
Published: December 2008

Die steigenden Forderungen nach Umweltverträglichkeit, Kosteneinsparung, und hochleistungsfähigen Endprodukten hat Wissenschaftler und Ingenieure veranlasst neue Materialien und Technologien zu entwickeln. Daraus resultierten beispielsweise die Polymer‐Metall Hybridstrukturen. Diese werden insbesondere in Transport‐ und moderner Bauindustrie angewandt. Geeignete herkömmliche Fügeverfahren dafür (Kleben und mechanische Fügeverfahren) sind üblicherweise entweder teuer, weisen limitierte Festigkeit und Anwendbarkeit auf oder sind nicht umweltfreundlich. Die im Rahmen dieser Arbeit behandelte neue Reibnieten („FricRiveting”︁) Methode für Polymer‐Metall Mischverbindungen wurde hierfür als alternative, zuverlässige, umweltfreundliche, und potenziell kostengünstige Punktverbindungstechnik entwickelt, beschrieben und nachgewiesen. In der einfachsten Variante des Reibnietens dringt eine in Rotation versetzte zylinderförmige metallische Niete in die Oberfläche eines oder mehrerer Kunststoff‐Grundwerkstoffe ein. Aufgrund der hohen Rotation bzw. des hohen Axialdruckes wird Reibungswärme erzeugt. Mit Erreichen einer vorprogrammierten Zeit erhöht sich die Prozesstemperatur signifikant. Dadurch wird die Spitze der Niete plastifiziert; in diesem Moment wird die Rotation verzögert und der Axialdruck in die Fügepartner erhöht. Als Folge verformt sich die Nietenpitze entsprechend des Druckverhältnisses. Nach der Abkühlungsphase wird die verformte Nietspitze formschlüssig im Kunststoff verankert. Die in dieser Arbeit vorgeschlagenen Theorien, und Mechanismen wurden bei Verbindungen von Polyetherimid (PEI) und Aluminium 2024‐T351 (Al‐Cu‐Mg Legierung) nachgewiesen. Punkt‐ und Überlappverbindungen mit hohem Festigkeits‐Wirkungsgrad unter Raumtemperatur (der Zugfestigkeit‐ Wirkungsgrad betrug bis zu ca. 97 % der Nietfestigkeit und der Scherzugfestigkeit‐Wirkungsgrad betrug bis zu ca. 70 % der Kunststofffestigkeit) wurden reibgenietet. Zum Schluss wurden die Gefügeänderung und mikrostrukturellen Eigenschaften dieser reibgenieteten Verbindungen beschrieben. Die im Laufe dieser Arbeit entstandenen wissenschaftlichen bzw. technischen Ergebnisse beweisen die Durchführbarkeit des Reibnietens. Als Ergebnis dieser Arbeit kann das Reibnieten als potenzielle zuverlässige, einfache, kostengünstige, und umweltfreundliche Fügetechnik für Polymer‐Metall Verbindungen vorgeschlagen werden.
Carbonated hydroxyapatite nanopowders for preparation of bioresorbable materials
Authors: Kovaleva E. S. , Shabanov M. P. , Putlayev V. I. , Filippov Ya. Yu. , Tretyakov Y. D. , Ivanov V. K.
Published: December 2008

Incorporation of carbonate ions to the crystal structure of carbonated hydroxyapatite (CHAp) leads to the formation of point defects (vacancies) in Ca‐ and OH‐sublattices as well as to microstrains revealed in CHAp nanocrystals. Various techniques, such as XRD, FTIR, TEM, FESEM/EDX, TG/DTA, AES (ICP), wet chemical analysis, Ca‐ionometry, microvolumetric analysis of evolved CO2, BET adsorption, were applied to determine an efficiency of carbonate substitution, and to quantify the elemental composition, as well as to characterize the structure of the carbonated hydroxyapatite and the site(s) of carbonate substitution. It was shown that there is insignificant incorporation of Na into the crystal structure of HAp. Over the range of 0–4 % wt. (x<0.25), the substitution of OH‐ by CO32‐ takes place leading to A‐Type of CHAp, further increase of CO32‐‐content enhances PO43‐‐substitution giving AB‐type of CHAp. According to in vitro test, the bioactivity of the samples is increasing with the growth of carbonate content due to accumulation of the defects in CHAp nanocrystals.
On the impact of managerial bonus systems on firm profit and market competition: the cases of pure profit, sales, market share and relative profits compared
Authors: Jansen Thijs , van Lier Arie , van Witteloostuijn Arjen
Published: December 2008

By designing remuneration schemes based on a bonus rewarding specific firm‐level outcomes, the owners/shareholders of a firm can manipulate the behavior of their managers. In practice, different bonus anchors take center stage: some are profit‐based, others use sales as the key yardstick and still different ones focus on relative performance vis‐à‐vis a peer group. In this paper, we focus on the impact of remuneration schemes on firm‐level profitability. The profit effect is investigated for (all possible combinations of) four bonus systems using delegation games. In the context of a linear Cournot model for two or three firms, we model a two‐ or three‐stage decision structure where, in the first stage (or first two stages), an owner decides on the bonus system for his manager and where, in the final stage, the manager takes the daily output decision for her firm. It appears that the bonus system based on relative (profits) performance is superior throughout. Copyright © 2008 John Wiley & Sons, Ltd.
Wave propagation velocity under a vertically vibrated surface foundation
Authors: Ahn Jaehun , Biscontin Giovanna , Roësset Jose M.
Published: December 2008

The ultimate objective of the research conducted by the authors is to explore the feasibility of determining reliable in situ values of soil modulus as a function of strain. In field experiments, an excitation is applied on the ground surface using large‐scale shakers, and the response of the soil deposit is recorded through receivers embedded in the soil. The focus of this paper is on the simulation and observation of signals that would be recorded at the receiver locations under idealized conditions to provide guidelines on the interpretation of the field measurements. Discrete models are used to reproduce one‐dimensional and three‐dimensional geometries. When the first times of arrival are detected by receivers under the vertical impulse, they coincide with the arrival of the P wave; therefore related to the constrained modulus of the material. If one considers, on the other hand, phase differences between the motions at two receivers, the picture is far more complicated and one would obtain propagation velocities, function of frequency and measuring location, which do not correspond to either the constrained modulus or Young's modulus. It is necessary then to conduct more rigorous and complicated analyses in order to interpret the data. This paper discusses and illustrates these points. Copyright © 2008 John Wiley & Sons, Ltd.
Modeling crack propagation path of anisotropic rocks using boundary element method
Authors: Ke Chien‐Chung , Chen Chao‐Shi , Ku Cheng‐Yu , Chen Chih‐Hao
Published: December 2008

In a cracked material, the stress intensity factors (SIFs) at the crack tips, which govern the crack propagation and are associated with the strength of the material, are strongly affected by the crack inclination angle and the orientation with respect to the principal direction of anisotropy. In this paper, a formulation of the boundary element method (BEM), based on the relative displacements of the crack tip, is used to determine the mixed‐mode SIFs of isotropic and anisotropic rocks. Numerical examples of the application of the formulation for different crack inclination angles, crack lengths, and degree of material anisotropy are presented. Furthermore, the BEM formulation combined with the maximum circumferential stress criterion is adopted to predict the crack initiation angles and simulate the crack propagation paths. The propagation path in cracked straight through Brazilian disc specimen is numerically predicted and the results of numerical and experimental data compared with the actual laboratory observations. Good agreement is found between the two approaches. The proposed BEM formulation is therefore suitable to simulate the process of crack propagation. Copyright © 2008 John Wiley & Sons, Ltd.
Urinary incontinence among institutionalized oldest old Chinese men in Taiwan
Authors: Chen Yi‐Ming , Hwang Shinn‐Jang , Chen Liang‐Kung , Chen Der‐Yuan , Lan Chung‐Fu
Published: December 2008

Aims

To explore prevalence and related factors for urinary incontinence (UI) among the oldest old institutionalized Chinese men in Taiwan.

Methods

All residents living in Banciao Veterans Care Home were invited for study. UI was defined as urinary leakage at least once weekly. Additional data items from the Minimum Data Set (MDS Nursing Home Chinese Version 2.1) were used to explore impact associated with physical function, cognitive status and quality of life (social engagement, SocE). Depressive symptoms were screened by the Short Form Geriatric Depression Scale.

Results

Data from 594 male residents (mean age: 80.9 ± 5.3 years) were analyzed. Among all study subjects, 92.8% were functionally independent, 20.4% had certain cognitive impairment and 8.2% had depressive symptoms. The prevalence of UI in the Banciao Veterans Care Home was 10.1%. Compared with residents without UI, subjects with UI had poorer physical function, cognitive status, and more depressive symptoms. The mean SocE score was 1.5 ± 1.3, and was similar between UI (+) and UI (−) subjects (1.4 ± 1.2 vs. 1.6 ± 1.3, P = 0.411). By multivariate logistic regression, poorer physical functional status, cognitive impairment and depressive symptoms were independent risk factors for UI (P < 0.05).

Conclusions

Poorer physical function, poorer cognitive status and depressive symptoms were all statistically significant independent risk factors for UI. However, SocE score (proxy indicator of quality of life) did not differ between subjects with and without UI. Further investigations are needed to evaluate the impact of UI on quality of life among oldest old institutionalized Chinese men in Taiwan. Neurourol. Urodynam. 28:335–338, 2009. © 2008 Wiley‐Liss, Inc.
Impact of urinary incontinence on the psychological burden of family caregivers
Authors: Gotoh Momokazu , Matsukawa Yoshihisa , Yoshikawa Yoko , Funahashi Yasuhito , Kato Masashi , Hattori Ryohei
Published: December 2008

Aims

The present study was conducted to assess the impact of urinary incontinence on the psychological burden of family caregivers providing care to disabled family members with urinary incontinence.

Materials and Methods

This survey was conducted using an Internet panel for family caregivers in Japan, consisting of 7,316 members. We requested the members to respond to an online questionnaire to assess the impact of urinary incontinence on the burden of caregivers. The questionnaire included basic characteristics, and the Japanese version of the Zarit Caregiver Burden Interview (ZBI) comprising 22 questions related to the impact of the patient's disabilities on the burden of their caregivers. Additionally, the participants were asked to include the level of care need, ranging from 0 to 5 according to the grade of disability of the cared individuals.

Results

Relevant data obtained from 757 caregivers were analyzed. Of these caregivers, 452 provided care to family members with urinary incontinence (group 1), and 305 provided care to those without urinary incontinence (group 2). The mean total ZBI score was significantly higher in group 1 than in group 2 (mean, 40.7 vs. 34.7, P < 0.001). The difference in the scores for each item was also significant in 20 of the 22 items. With regard to the level of care need, irrespective of the level, the ZBI scores in group 1 tended to be higher than those in group 2.

Conclusions

The present survey demonstrated a negative impact of urinary incontinence on the psychological burden of family caregivers. Neurourol. Urodyn. 28:492–496, 2009. © 2008 Wiley‐Liss, Inc.
Partial bladder outlet obstruction reduces the tissue antioxidant capacity and muscle nerve density of the guinea pig bladder
Authors: de Jongh Rik , Dambros Miriam , Haenen Guido R.M.M. , den Hartog Gertjan J.M. , Bast Aalt , van Kerrebroeck Philip E.V. , van Koeveringe Gommert A.
Published: December 2008

Aims

Reactive nitrogen and oxygen species (RNOS) likely play a role in the development of bladder dysfunction related to bladder outlet obstruction. Antioxidants protect against these free radicals. The aim of our study was to investigate the effect of bladder outlet obstruction on the endogenous antioxidant status of the bladder and to correlate this to bladder structure and function.

Methods

In 16 guinea pigs either a partial outlet obstruction or a sham operation was induced. The contractile responses of detrusor strips to electrical field stimulation (EFS), acetylcholine, potassium, and ATP were monitored 4 weeks after the operation. The nerve density in bladder tissue was determined by using the non‐specific nerve marker PGP 9.5. Separate antioxidants and the total antioxidant status were assessed using the trolox equivalent antioxidant capacity (TEAC) test.

Results

Contractile responses of detrusor strips to EFS were for the greater part based on neurogenic stimulation. The nerve‐mediated responses in strips from obstructed bladders were lower compared to the sham group. Obstructed bladders showed a patchy denervation and the nerve density was significantly lower compared to the sham group. The total antioxidant capacity, the glutathione and the glutathione reductase (GR) levels significantly decreased in obstructed bladders compared to the sham group.

Conclusion

This study demonstrates that the antioxidant status of guinea pig bladders exposed to outlet obstruction decreased which might be associated with the observed reduction in nerve density. The results strengthen the hypothesis that oxidative stress is involved in the pathophysiology of bladder dysfunction related to obstructed bladders. Neurourol. Urodynam. 28:461–467, 2009. © 2008 Wiley‐Liss, Inc.
The Number of Voiding Radiographs During Cystourethrography in Women With Stress Incontinence or Prolapse Can Be Reduced to Enhance Safety Without Compromising Study Interpretation
Authors: Guild Jeffrey , Takacs Elizabeth , Kircher Stephen , Arbique Gary , Zimmern Philippe E.
Published: December 2008

Aim

Based on a prior study, over 60% of the average radiation dose per cystourethrography (CU) originated from lateral radiograph images (RI). This analysis focuses on the feasibility of decreasing the number of RI without compromising study interpretation.

Methods

Material and Method: Following IRB approval, all RIs from the initial study in women with incontinence and/or bladder prolapse were assessed at random for reading consistency (inter‐rater reliability (IRR)) and reliability (intra‐rater reliability (IaRR)) by four independent reviewers. Interpretation guidelines on urethral readability were established and 15 repeated RIs tested for IaRR. Two months later, the reviewers selected the best two RIs for each CU with the RI presented in a random order.

Results

From 88 CU exams providing 304 RIs, good IRRs for readability (κ=0.82, ICC=0.80) and interpretation (κ=0.60, ICC=0.57) were found between reviewers. Mean IaRR for readable versus unreadable categories was 87% and among readable images was 95% for interpretation. The RIs judged best had a high IRR (κ=0.83, ICC=0.83) and were predominantly from the early and middle phases of the void.

Conclusion

A high level of agreement was found for urethral readability and interpretation between reviewers of varying experience using pre‐established guidelines. No more than 3 RIs were required for study interpretation and those views were from the early to middle phase of voiding, thus allowing a radiation dose reduction without compromising the quality of the CU exam. Neurourol. Urodynam. 28:385–389, 2009. © 2008 Wiley‐Liss, Inc.
Observations relating to urinary sensation during detrusor overactivity
Authors: Lowenstein Lior , Pham Thythy , Abbasy Shameem , Kenton Kimberly , Brubaker Linda , Mueller Elizabeth R. , Shott Susan , Vardi Yoram , Gruenwald Ilan , FitzGerald Mary P.
Published: December 2008

Aims

To describe the temporal relationship between increases in lower urinary tract (LUT) sensation and changes in detrusor and/or urethral pressures measured in real time.

Methods

We reviewed 33 multichannel urodynamic tracings that included a continuous recording of LUT sensation and that demonstrated detrusor overactivity incontinence (DOI) or detrusor overactivity (DO). Four physicians reviewed each urodynamic tracing and reached agreement about the temporal relationship between LUT sensation and detrusor contraction.

Results

Median age was 60 (36–82) years. Fourteen (42%) had urodynamic diagnoses of mixed incontinence, 18 (55%) had DOI, and 1 (3%) had DO without DOI. We reviewed 119 episodes of detrusor overactivity from the 33 recordings. We found no difference in change in sensation level when comparing DO episodes with DOI episodes or between different urodynamic diagnoses (P > 0.5). There was no dominant temporal pattern seen for the whole group (P = 0.84), that is, there was no evidence that the change in sensation level was more likely to occur before, during, or after DO/DOI episodes. When evaluating the changes in the urethral pressure, the most common pattern seen was an increase in sensation level after a fall in urethral pressure, but no dominant pattern was seen.

Conclusions

Our findings suggest that increased LUT sensation during DO/DOI is not reliably caused by measurable alterations in bladder or urethral pressure. Neurourol. Urodyn. 28:497–500, 2009. © 2008 Wiley‐Liss, Inc.
Design and control of agile automated CONWIP production lines
Authors: Hopp Wallace J. , Iravani Seyed M.R. , Shou Biying , Lien Robert
Published: December 2008

In this article, we study the design and control of manufacturing cells with a mix of manual and automated equipment, operating under a CONWIP pull protocol, and staffed by a single agile (cross‐trained) worker. For a three‐station line with one automated station, we fully characterize the structure of the optimal control policy for the worker and show that it is a static priority policy. Using analytical models and extensive simulation experiments, we also evaluate the effectiveness of practical heuristic control policies and provide managerial insights on automation configuration design of the line. This characterization of the worker control policy enables us to develop managerial insights into the design issues of how best to locate and concentrate automation in the line. Finally, we show that, in addition to ease of control and greater design flexibility, the CONWIP protocol also offers higher efficiency and robustness than does the push protocol. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 2009
Lanchester models and the battle of Britain
Authors: Johnson Ian R. , MacKay Niall J.
Published: December 2008

We fit deterministic generalized Lanchester models to daily sortie and loss data from the Battle of Britain. The best fit for the period 14th August to 30th October 1940 is δB ∼ G1.2, δG ∼ G0.9, where B and G are RAF Fighter Command and Luftwaffe sortie numbers, and δB and δG are daily loss numbers, respectively. The data naturally divide into two phases, with losses (as a proportion of overall sortie numbers) much reduced after 15th September. Fits were generally better for the first phase than for the second, and for British losses than for German; in every case the dependence on G is stronger than that on B. Days with higher sortie numbers on average favored the Luftwaffe, whereas the loss‐ratio was not significantly dependent on the force ratio. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 58: 210–222, 2011
Technical note: A computationally efficient algorithm for undiscounted Markov decision processes with restricted observations
Authors: Davis Lauren B. , Hodgson Thom J. , King Russell E. , Wei Wenbin
Published: December 2008

We present a computationally efficient procedure to determine control policies for an infinite horizon Markov Decision process with restricted observations. The optimal policy for the system with restricted observations is a function of the observation process and not the unobservable states of the system. Thus, the policy is stationary with respect to the partitioned state space. The algorithm we propose addresses the undiscounted average cost case. The algorithm combines a local search with a modified version of Howard's (Dynamic programming and Markov processes, MIT Press, Cambridge, MA, 1960) policy iteration method. We demonstrate empirically that the algorithm finds the optimal deterministic policy for over 96% of the problem instances generated. For large scale problem instances, we demonstrate that the average cost associated with the local optimal policy is lower than the average cost associated with an integer rounded policy produced by the algorithm of Serin and Kulkarni Math Methods Oper Res 61 (2005) 311–328. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 2009
Hybrid numerical techniques for the modelling of radiofrequency coils in MRI
Authors: Li Bing Keong , Liu Feng , Weber Ewald , Crozier Stuart
Published: December 2008

Radiofrequency (RF) coils for use in MRI can have a significant effect on both the signal‐to‐noise‐ratio of MR images and the specific absorption rate inside the biological sample. In the past, prototypes were constructed and tested to investigate the performance of the RF coils and often required several iterations to achieve an acceptable result. However, with the advancement in computational electromagnetic techniques, RF coil modelling has now become the modus operandi of coil design because it can produce accurate numerical results, thus reducing the time and effort spent in designing and prototyping RF coils. Two hybrid methods –method of moments (MoM)/finite difference time domain (FDTD) and MoM/finite element method (FEM) – for RF coil modelling are presented herein. The paper provides a brief overview of FDTD, FEM and MoM. It discusses the hybridisation of these methods and how they are integrated to form versatile techniques. The numerical results obtained from these hybrid methods are compared with experimental results from prototype coils over a range of operating frequencies. The methods are then applied to the design of a new type of phased‐array coil – the rotary phased array. From these comparisons, it can be seen that the numerical methods provide a useful aid for the design and optimisation of RF coils for use in MRI. Copyright © 2008 John Wiley & Sons, Ltd.
Design of multichannel MAC protocols for wireless ad hoc networks
Authors: Lo Shou‐Chih
Published: December 2008

Medium access control (MAC) protocols coordinate channel access between wireless stations, and they significantly affect the network throughput of wireless ad hoc networks. MAC protocols that are based on a multichannel model can increase the throughput by enabling more simultaneous transmission pairs in the network. In this paper, we comprehensively compare different design methods for multichannel MAC protocols. We classify existing protocols into different categories according to the channel negotiation strategies they employ. The common problems that may be encountered in multichannel design are discussed. We then propose a hybrid protocol that combines the advantages of the two methods of a common control channel and a common control period. The simulation results show that our proposed protocol can significantly outperform two representative protocols. Copyright © 2008 John Wiley & Sons, Ltd.
Optimum Steiner ratio for gradient‐constrained networks connecting three points in 3‐space, part I
Authors: Prendergast K. , Thomas D.A. , Weng J.F.
Published: December 2008

It is well known that when there is no gradient constraint, the minimum Steiner ratio for three terminals is achieved with an equilateral triangle, and the ratio is $\sqrt{3} \over 2$. This article shows that in the gradient‐constrained cases, the configuration of three terminals giving the minimum Steiner ratio is also an equilateral triangle. However, there are an infinite number of such triangles with differing orientations in 3‐space. We determine the behavior of the Steiner ratio over all of these equilateral triangles and thereby show that the minimum ratio occurs when the triangle is in the vertical plane with one edge vertical. The minimum ratio tends to $3 \over 4$ as the value of the gradient constraint tends to zero. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
On irreducible no‐hole L(2, 1)‐coloring of trees
Authors: Laskar Renu C. , Matthews Gretchen L. , Novick Beth , Villalpando John
Published: December 2008

We consider a variant of the channel assignment problem in which frequencies are assigned to transmitters in a way that avoids interference while ensuring that all frequencies within the bandwidth are used. This is modeled as an L(2, 1)‐coloring of a graph which is no‐hole and irreducible in the sense that no color can be replaced with a smaller one. In this article, we show that if the network is any tree other than a star, then frequencies may be assigned in this fashion without increasing the bandwidth; that is, we show that for any such tree T, the inh‐span of T is equal to its span. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
Lower bounding techniques for the degree‐constrained network design problem
Authors: Şahin Güvenç , Ahuja Ravindra K.
Published: December 2008

A typical network design problem consists of identifying a subnetwork of a given network that satisfies a set of constraints and minimizes the cost of flow. We consider degree‐constrained network design problems where we specify an upper limit on the number of arcs built at each node. We propose two lower bounding techniques using the concept of lower planes. The first lower bound is based on a known lower plane for network design problems; our second lower bound is stronger than the first, yet has the same polynomial computational complexity. We illustrate both lower bounds using a numerical example, test their performance, and present a real‐life case study from the area of railroad planning problems. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
Heat diffusion in layered media via the thin‐layer method
Authors: Joanni Andreas E. , Kausel Eduardo
Published: December 2008

The thin‐layer method is a semi‐analytical, numerical tool that has been successfully used in the past for wave motion in layered media, and differs from finite elements in that the medium is discretized only along a subset of the problem's dimensions, i.e. it combines partial discretization with analytical solutions. This paper shows that it can be applied just as well to heat diffusion, and results are given for impulsive as well as distributed point and dipole thermal sources with formulations in Cartesian and cylindrical coordinates. In essence, the method involves the discretization of the governing equations in the direction of layering together with analytical solutions for the remaining directions and for the variation in time. The solutions in response to spatially and temporally impulsive sources can also be used as fundamental solutions in the context of a boundary element formulation. This is illustrated herein by means of an example of a concrete slab overlain by two layers of carbon fiber reinforced polymers (CFRP), where a penny‐shaped crack is meant to simulate an area where the CFRP has debonded from the concrete. Copyright © 2008 John Wiley & Sons, Ltd.
Superconvergence of finite volume methods for the Stokes equations
Authors: Cui Ming , Ye Xiu
Published: December 2008

A general superconvergence result of finite volume method for the Stokes equations is obtained by using a L2 projection post‐processing technique. This superconvergence result can be applied to different finite volume methods and to general quasi‐uniform meshes.© 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2009
The ill‐posed retrieval of aerosol extinction coefficient profiles (Poster Presentation)
Authors: Pornsawad P. , Böckmann C. , Ritter C. , Rafler M.
Published: December 2008

We present an improvement for the determination of aerosol extinction coefficient profiles from Raman lidar data in using regularization. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)