bluuebunny/crossref_metadata_2025 huggingface dataset:
Critical load of an axially compressed sandwich cylindrical panel
Authors: Laszczyk Zbigniew , Szyc Waclaw
Published: January 2007

The problem of critical load of an axially compressed open sandwich cylindrical shell with two straightlinear edges free is presented. Large angle of the shell sector, geometrical and physical symmetry of the facings are assumed. The simply formula for calculation critical stress in the shell is presented. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vibration of a porouse‐cellular circular plate
Authors: Magnucka‐Blandzi Ewa
Published: January 2007

The subject of investigation is a circular porous‐cellular plate under uniform pressure. Mechanical properties of the isotropic porous cellular metal vary accross the thickness of the plate. Middle plane of the plate is its symmetry plane. Fields of diseplacements and stresses with respect the nonlinear hypothesis are described. Basing on Hamilton principle three motion equations of the plate are formulated. These equations are approximately solved. The vibration problem is reduced to the second‐order differential equation. Numerical investigations are realised for family of plates. Natural frequencies are determined. The obtained results are shown in Figures. To the end of the investigation comparition analyses with respect to homogeneous plates is presented. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A novel h‐adaptive finite element method for standard dissipative media at finite strains based on energy minimization
Authors: Mosler J. , Ortiz M.
Published: January 2007

A novel h‐adaptive finite element strategy for standard dissipative media at finite strains based on energy minimization is presented. The method can be applied to any (incremental) minimization problem to be analyzed by finite elements. Similarly to an error estimator by Babǔska & Rheinboldt, the proposed error indicator is based on solving a local Dirichlet‐type problem. However, in contrast to the original work, a different error indicator is considered. Provided the underlying physical problem is governed by a minimization problem, the difference between the energy of the elements defining the local problem computed from the initial finite element interpolation and that associated with the local Dirichlet‐type problem is used as an indicator. If this difference reaches a certain threshold, the elements defining the local problem are refined by applying a modified longest edge bisection according to Rivara. Since this re‐meshing strategy leads to a nested family of triangulations, the transfer of history variables necessary to describe dissipative materials is relatively inexpensive. The presented h‐adaption is only driven by energy‐minimization. As a consequence, anisotropic meshes may evolve if they are energetically favorable. The versatility and rate of convergence of the resulting approach are illustrated by means of selected numerical examples. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Frictional Contact of Rubber on rough Surfaces
Authors: Nettingsmeier Jana , Wriggers Peter
Published: January 2007

The aim of this work is to investigate the frictional behaviour of rubber on rough rigid surfaces. Rubber friction is composed of hysteretic and adhesional effects. The main focus lies on the hysteresis theory which motivates rubber friction with the internal damping inside the viscoelastic material.

It is necessary to perform a multiscale analysis to regard the roughness of the surface on all important length scales. The fractal surface is approximated by a superposition of harmonic functions. The simulations will start at the lowest wavelength and proceed to larger scales by replacing the smaller roughness with the ascertained friction law. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bicriterion Optimization of Cold‐Formed Thin‐Walled Beams
Authors: Rodak Marcin
Published: January 2007

Bicriterion optimization of cold‐formed thin‐walled beams is presented in this paper. Simply supported beams with the crosssection similar to I‐section are considered. They are loaded with bending moments on both ends. The area of the cross section and relative maximum deflection are optimization criteria. The geometrical, strength and stability constraints are taken into account during the optimization process. The results of an example problem are presented in the form of tables. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anisotropic damage of shock wave‐loaded plates
Authors: Stoffel Marcus , Schmidt Rüdiger , Weichert Dieter
Published: January 2007

In the present study circular metal plates are subjected to impulsive loadings in shock tubes. The damage growth in the plate specimens until failure is predicted by finite element simulations. The aim is to validate the applied isotropic and anisotropic damage laws by means of comparisons between calculated and measured deformations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inverse Identification of Delamination Regions in Layered CFRP‐Composites
Authors: Tsotsova Rumena , Schnack Eckart
Published: January 2007

In this paper we are concerned with the complete non‐destructive reconstruction (shape, depth and topology) of delaminations in one damaged interface in layered composites using the Cauchy data on the outer boundary. The proposed method combines an iterative algorithm for solution of mixed ill‐posed elliptical boundary value problems and a parameter estimation in sense of the ill‐posed optimization problems. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vibrations of a Pendulum with Oscillating Support and Extra Torque
Authors: Borowiec Marek , Litak Grzegorz , Troger Hans
Published: January 2007

The motion of a driven planar pendulum with vertically periodically oscillating point of suspension and under the action of an additional constant torque is investigated. We study the influence of the torque strength on the transition to chaotic motions of the pendulum using Melnikov's analysis. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation and Measurements of Rolling Tire Dynamics
Authors: Brinkmeier Maik , Nackenhorst Udo
Published: January 2007

The simulation of rolling tires including stationary rolling, modal analysis, excitation with roughness of road surfaces and sound radiation is presented for state of the art industrial tire models. The target of this research, part of the german project “Leiser Straßenverkehr”, is the reduction of trafic noise, whereas the main source, namely the tire/road system, is investigated in contrast to other techniques like sound insulating walls.

The needs and methods for the solution of the resulting large scale problems are discussed next to special properties of rotating structures, high frequency behavior of rubber material and approaches for the reduction of computational cost. For the validation of the model measurements of real tires and roads are used. These include shaker tests of the standing tire and acoustics of tires rolling on a drum. The same set–ups are applied to the simulation for the comparison of frequency response functions and sound pressure levels. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electro‐vibro‐acoustic Simulation of Linear Vibrations in Ducts
Authors: Kletschkowski Thomas , Sachau Delf , Umer Draz Rana
Published: January 2007

Due to standing waves the creation of artificial free‐field conditions is required to detect sound sources in weakly damped interiors. Normally sound absorbing material is mounted on the interior walls to eliminate unwanted reflections. In contrast to this time consuming procedure, the present paper describes a local approach that is based on a sound intensity probe with an active free‐field (SIAF). To study the dynamical behavior of a first SIAF‐prototype that consists of two electro‐dynamical loudspeakers mounted at the ends of a duct, an electro‐vibro‐acoustical model was implemented in Matlab/Simulink, and the dynamic behavior of the system was analyzed numerically. The results of these simulations proved that a one‐dimensional free‐field can be produced successfully, if a wave‐separation approach together with an adaptive LMS‐algorithm is applied. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient Calculation of Tread Block Vibrations
Authors: Moldenhauer Patrick , Kröger Matthias
Published: January 2007

A model is presented that allows to calculate the dynamics of tyre tread blocks. The numerical efficiency is achieved by the combination of static and important modal ansatz functions, also known as Hurty/Craig/Bampton transformation. Nonlinear single point contacts provide the contact forces and consider the surface roughness. The non‐smooth friction characteristic is approximated an arctan function and a parameter study of the slope parameter is conducted. Typical stickslip limit cycles of the tread block are shown. These phenomena can have a part in the tyre/road noise. Experimental results qualitatively agree with the modelled tread block vibrations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impedance Losses in Negative Capacitance Circuits for Semi‐Passive Vibration Control with Piezo‐Ceramics
Authors: Oleskiewicz Robert , Neubauer Marcus , Krzyzynski Tomasz
Published: January 2007

Damping or absorbing effect in vibration control applications with piezo elements may be customized by an external impedance shunt branch connected to the plates of the piezo element. The negative capacitance present in the shunt significantly improves the damping and absorbing performance of such systems. The circuit is built up of an electronic gyrator realized by the operational amplifier, which is in reality not the ideal element. Therefore the performance of the proposed systems is limited, concerning the maximum voltages and currents at which the operational amplifiers can operate. In the paper, the finite gain of the operational amplifier, together with the loss impedances and the feedback gain factor is studied. The influence of the certain imperfections in the design of the electronic gyrator is based on 1DOF mechanical oscillator, with a piezo stack. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quietschen von KFZ‐Scheibenbremsen
Authors: Schlagner S. , von Wagner U.
Published: January 2007

Quietschen ist ein lästiges Problem bei KFZ‐Scheibenbremsen, welches aus Selbsterregten Schwingungen resultiert. In der vorliegenden Arbeit wird der Frage nachgegangen, inwieweit der Phasenversatz zwischen Reibungskräften und in‐plane Bewegung des Bremsbelags ein Kriterium für die Quietschfreudigkeit einer Scheibenbremse sein kann. Entsprechende Ansätze ergeben sich aus theoretischen Vorüberlegungen [1] und experimentellen Untersuchungen [2]. Anhand von einfachen Modellen wird hier geklärt, ob diese beiden Größen den Anregungsmechanismus für Bremsenquietschen abbilden können. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inverse Eigenvalue Problems in Structural Dynamics
Authors: Wagner Nils
Published: January 2007

We consider the numerical solution of inverse eigenvalue problems (IEP). Two different formulations are used. The methods are applied to a certain mechanical system. Due to the special structure of the mass and stiffness matrix we benefit from a secular equation. The roots of that equation are the eigenvalues of the system. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the crosswind stability of high speed railway vehicles
Authors: Wetzel Christian , Proppe Carsten
Published: January 2007

The crosswind stability against overturning is a major national design criterium for high‐speed railway vehicles. Due to the increasing interoperability in Europe it has also become an important international task. Especially modern light‐weight trains are at risk to fail and counter‐measures as for example wind‐fences or adding extra weight in the underbelly are always very expensive. In recent years efforts were made to derive an uniform rule in certifying railway vehicles. In this case especially probabilistic methods were proposed. These probabilistic technics are common design criteria for wind turbines. This paper presents a sophisticated method to compute the reliability of railway vehicles under strong crosswind. In consideration of the given gust signal and the high‐frequency, turbulent fluctuations of the wind the response of a simplified train model is computed. The major failure criterium to determine the reliability is the lowest wheel‐rail contact force of the railway vehicle. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling and Computation of 3D Discontinuities in Solids
Authors: Jäger P. , Mergheim J. , Kuhl E. , Steinmann P.
Published: January 2007

Strong and weak discontinuities can appear in different fields of mechanics. Some obvious examples where strong discontinuities arise are stationary and propagating cracks. This manuscript will thus discuss a geometrically nonlinear, meshindependent finite element framework for the modelling of stationary and propagating cracks in three dimensional continua. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Constitutive Model for Magnetostrictive Materials ‐ Theory and Finite Element Implementation
Authors: Linnemann Konrad , Klinkel Sven
Published: January 2007

A 3D macroscopic constitutive law for hysteresis effects in magnetostrictive materials is presented and a finite element implementation is provided. The novel aspect of the thermodynamically consistent model is an additive decomposition of the magnetic and the strain field in a reversible and an irreversible part. Employing the irreversible magnetic field is advantageous for a finite element implementation, where the displacements and magnetic scalar potential are the nodal degrees of freedom. To consider the correlation between the irreversible magnetic field and the irreversible strains a one‐to‐one relation is assumed. The irreversible magnetic field determines as internal variable the movement of the center of a switching surface. This controls the motion of the domain walls during the magnetization process. The evolution of the internal variables is derived from the magnetic enthalpy function by the postulate of maximum dissipation, where the switching surface serves as constraint. The evolution equations are integrated using the backward Euler implicit integration scheme. The constitutive model is implemented in a 3D hexahedral element which provides an algorithmic consistent tangent stiffness matrix. A numerical example demonstrates the capability of the proposed model to reproduce the ferromagnetic hysteresis loops of a Terfenol‐D sample. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
CO2 foaming based on polystyrene/poly(methyl methacrylate) blend and nanoclay
Authors: Han Xiangmin , Shen Jiong , Huang Hanxiong , Tomasko David L. , Lee L. James
Published: January 2007

A poly(methyl methacrylate) (PMMA) and nanoclay composite was dispersed into polystyrene (PS) using a twin‐screw extruder. The mixture was then batch foamed with supercritical CO2. It was found that the cell density of foams based on the blend is higher than that based on the weight average of the two pure polymer components at the same foaming conditions. The cell size decreases and the cell density increases with the increase of the PMMA domain size. One explanation is that the large PMMA domains serve as a CO2 reservoir and the nucleation in the PS phase is enhanced by the diffusion of CO2 from the PMMA phase to the PS phase. Very small PMMA domains cannot function as a CO2 reservoir, and so they are not able to facilitate the nucleation. A much higher cell density and smaller cell size were observed when nanoclay was located at the interface of the PMMA and the PS domains, serving as the heterogeneous nucleating agents. POLYM. ENG. SCI., 47:103–111, 2007. © 2007 Society of Plastics Engineers
Computation of starch cationization performances by twin‐screw extrusion
Authors: Berzin Françoise , Tara Ahmed , Tighzert Lan , Vergnes Bruno
Published: January 2007

A theoretical model for the cationization of plasticized wheat starch in a modular seIf‐wiping co‐rotating twin screw extruder was developed. Our objective was to build a model which would be able to predict the evolution of the cationization reaction along the screws, in relation with the processing conditions and the geometry of the twin screw extruder. Based on previous studies on reactive extrusion modeling, the present model takes into account the interactions occurring between the flow conditions encountered in the extruder and the kinetics of the reaction. It allows one to predict the influence of operating parameters such as reagent concentrations, feed rate, screw speed, and barrel temperature on the reaction extent. Depending on conditions, degrees of substitution in the range 0.01–0.05 are obtained, with efficiencies between 30 and 90%. A good agreement is found between theoretical results and experimental measurements, allowing future use of the model for optimization and scale‐up purposes. POLYM. ENG. SCI., 47:112–119, 2007. © 2007 Society of Plastics Engineers
Processability, property, and morphology of biodegradable blends of poly(propylene carbonate) and poly(ethylene‐co‐vinyl alcohol)
Authors: Jiao J. , Wang S.J. , Xiao M. , Xu Y. , Meng Y.Z.
Published: January 2007

Biodegradable blends of poly(propylene carbonate) (PPC) and poly(ethylene‐co‐vinyl alcohol) (EVOH) were melt compounded in a batch mixer followed by compression molding. The processability, mechanical properties, thermal behavior, and morphologies of the blends were investigated with torque rheometer, Fourier transform infrared spectroscopy, tensile tests, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. Torque rheometry indicated good interfacial miscibility between PPC and EVOH phases, and then fourier transform infrared spectroscopy spectra demonstrated that a certain extent of hydrogen‐bonding interactions between PPC and EVOH matrix in the blends. A study of the mechanical properties and thermal behavior showed that the EVOH incorporation can significantly enhance the tensile strength, thermal stability, and crystallinity of the blends. Moreover, dynamic mechanical analysis and differential scanning calorimetry both revealed that PPC and EVOH were compatible to some extent. Further, scanning electron microscopic examination also revealed the good interfacial adhesion between EVOH and PPC phases. POLYM. ENG. SCI., 47:174–180, 2007. © 2007 Society of Plastics Engineers
Processing, rheology, and storage stability of recycled EVA/LDPE modified bitumen
Authors: García‐Morales M. , Partal P. , Navarro F.J. , Martínez‐Boza F.J. , Gallegos C.
Published: January 2007

The optimum processing conditions for the manufacture of polymer‐modified bitumens (PMBs), as well as the rheological properties of the final polymer‐bitumen blends, strongly depend on the characteristics of the mixing device used. The present work is focused on the comparison among the kinetics of the mixing process and the rheological properties and microstructural characteristics of PMBs manufactured in two different mixers. Thus, blends of 60/70 penetration grade bitumen and recycled EVA/LDPE were processed in both high and low‐shear devices. Knowledge on the evolution of shear viscosity and microstructure with time, as well as on the mechanical properties of the final polymer‐bitumen blends, was gained from rheological and modulated DSC tests, and optical microscopy. The results obtained demonstrate that processing in the high‐shear device yields a significant decrease in the time needed for the polymer‐bitumen blend to reach the final stage of the manufacturing process, as well as an important reduction in bitumen oxidation and enhanced properties in a wide range of in‐service temperatures. However, polymer‐bitumen blends manufactured in the high‐shear device are not stable during its storage at high temperature. POLYM. ENG. SCI., 47:181–191, 2007. © 2007 Society of Plastics Engineers
Synthesis and characterization of a thermotropic liquid‐crystalline poly[2,5‐bis(4′‐alkoxycarbonylphenyl) styrene]
Authors: Zhu Zhiguo , Zhi Junge , Liu Anhua , Cui Jiaxi , Tang Hui , Qiao Wenqiang , Wan Xinhua , Zhou Qifeng
Published: January 2007

We report the synthesis and characterization of a series of novel mesogen‐jacketed liquid‐crystalline polymers, poly[2,5‐bis(4′‐alkoxycarbonylphenyl)styrene]s (1‐m, where m is the number of carbon atoms in the alkyl tails), along with the corresponding monomers, 2,5‐bis(4′‐alkoxycarbonylphenyl)styrenes (2‐m), and their precursors, 2,5‐bis(4′‐alkoxycarbonylphenyl)toluenes (3‐m). The influence of the tail length on the thermotropic properties of the two types of low‐molecular‐mass compounds and macromolecules was investigated with a combination of differential scanning calorimetry, polarized optical microscopy, and wide‐angle X‐ray diffraction techniques. Except for compound 3‐3, which exhibited a monotropic nematic phase, all members of the low‐molar‐mass molecules developed no mesophase during both heating and cooling processes. The glass‐transition temperatures of the polymers decreased as the tail lengths increased. The 5% weight loss temperatures of all the polymers under a nitrogen atmosphere were above 360 °C, indicating quite high thermal stability. Although polymers 1‐1 and 1‐2 were non‐liquid‐crystalline, columnar nematic phases were observed for the remaining homopolymers with longer alkyl tails. The mesophases of 1‐3 to 1‐9 that developed at high temperatures remained upon cooling to room temperature, whereas those of 1‐10 to 1‐12 disappeared during the cooling process. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 830–847, 2007.
Poly(thienyl‐phenylene)s with macromolecular side chains by oxidative polymerization of well‐defined macromonomers
Authors: Cianga I. , Mercore V. M. , Grigoras M. , Yagci Y.
Published: January 2007

Well‐defined polystyrene (PSt), poly(ε‐caprolactone) (PCL) or poly(2‐methyloxazoline) (POx) based polymers containing mid‐ or end‐chain 2,5‐ or 3,5‐dibromobenzene moieties were prepared by controlled polymerization methods, such as atom transfer radical polymerization (ATRP), ring opening polymerization (ROP), or cationic ring opening polymerization (CROP). These polymers were subsequently modified by Suzuki type coupling reactions with 2‐thiophene boronic acid. The resulting polymers, containing a conjugated sequence with 2‐thienyl groups at the extremities, could be further used as macromonomers in chemical oxidative polymerization in the presence of anhydrous FeCl3. Poly(thienyl‐phenylene)s having the respective PSt or PCL chains as lateral subtituents were obtained in this way. All the starting, intermediate, or final polymers were structurally analyzed by spectroscopic methods (1H and 13C NMR, IR) and gel permeation chromatography (GPC) measurements. Thermal behavior of the macromonomers and final polymers was investigated by differential scanning calorimetry (DSC) analyses. Optical properties of the polymers were monitored by UV and fluorescence spectroscopy. The emission spectra of the polymers show a clear bathochromic shift of the λmax emission in all the cases with respect to the monomers because of the extending of the conjugation length. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 848–865, 2007.
Incorporation of silver/carbon nanoparticles into poly(methyl methacrylate) via in situ miniemulsion polymerization and its influence on the glass‐transition temperature
Authors: López‐Martínez Erika I. , Márquez‐Lucero Alfredo , Hernández‐Escobar Claudia A. , Flores‐Gallardo Sergio G. , Ibarra‐Gómez Rigoberto , Yacamán Miguel J. , Zaragoza‐Contreras E. Armando
Published: January 2007

Silver/carbon nanoparticles (9 nm) were incorporated, as reinforcements, into a matrix of poly(methyl methacrylate) via in situ miniemulsion polymerization. It was found by differential scanning calorimetry that the glass‐transition temperature of the poly(methyl methacrylate) showed an improvement of 14 °C with only 0.5 wt % nanoparticles in comparison with a pure poly(methyl methacrylate) control, which was also obtained by miniemulsion polymerization under the same conditions. This increase was related to a polymer chain mobility restriction due to a combination of bound plastic and joint plastic shell effects at the interphase and the surrounding regions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 511–518, 2007.
DC characterization of laser‐debonded GaN HEMTs
Authors: Chan C. P. , Leung K. K. , Pilkuhn M. , Surya C. , Yue T. M. , Pang G. , Schweizer H.
Published: January 2007

We report experimental investigation of laser‐assisted debonding of GaN high electron mobility transistors (HEMTs) grown by metalorganic chemical vapor deposition (MOCVD) technique on sapphire substrates. The debonded HEMTs were transferred onto silicon substrate for better thermal dissipation during operation. Dc characterization indicated no degradation in the I–V characteristics as long as the optimized laser power was used in the debonding process. Transmission electron microscopy (TEM) of the AlGaN/GaN heterojunctions before and after the laser debonding process did not indicate any increase in the dislocation density at the heterointerface. We have also conducted detailed characterizations of the low‐frequency noise properties to investigate the defect properties over the entire active area of the device. Experimental data on the voltage noise power spectra measured from the same device before and after laser debonding indicated no significant change in the magnitude of the flicker noise over a wide temperature range. The results of XRD measurements revealed that the FWHM values before and after debonding are basically the same and also suggested that both out‐of‐plane tensile and in‐plane compressive stresses present were both removed after the laser processing. Our results clearly demonstrate that the laser‐assisted debonding process did not result in the increase in the material defect density. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural properties of silica gels prepared from oxalic‐acid‐catalyzed tetraethoxysilane sonohydrolysis
Authors: Donatti D. A. , Ruiz A. Ibañez , Vicelli M. R. , Vollet D. R.
Published: January 2007

About ∼2.1 × 10−3 mol SiO2 cm−3 and ∼88%‐volume liquid‐phase silica wet gels were prepared from oxalic‐acid‐catalyzed tetraethoxysilane (TEOS) sonohydrolysis. Aerogels were obtained by supercritical CO2 extraction. The samples were analyzed by thermogravimetry, small‐angle X‐ray scattering and nitrogen adsorption. Wet gels can be described as mass fractal structures with fractal dimension D ∼ 1.94 and structural characteristic length ξ changing between ∼3.3 to ∼3.0 nm in the studied range of the catalyst concentration. A fraction of the porosity is apparently eliminated in the supercritical process. The values of the BET specific surface SBET, the total pore volume VP and the mean pore size lP of the aerogels were found to change almost randomly around the mean values SBET = 874 m2 g−1, VP = 0.961 cm3 g−1 and lP = 4.4 nm with catalyst concentration variation. These values were not substantially different from those from an equivalent HCl‐catalyzed aerogel. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of substrates on the statical and dynamical properties of ferroelectric thin films
Authors: Wesselinowa J. M. , Dimitrov Al. B.
Published: January 2007

Based on the transverse Ising model using a Green's function technique it is shown that the influence of the substrate induces strong changing of various statical and dynamical properties due to different exchange interactions between the ferroelectric thin film and the substrate. Properties such as the phase transition temperature, the polarization, the soft‐mode energy, the damping and the dielectric function were found to be highly dependent upon the magnitude and the kind (tensile or compressive) of the stress due to the substrate. There is some competition between the surface and substrate effects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of exacerbation rates in asthma and chronic obstructive pulmonary disease: example from the TRISTAN study
Authors: Keene Oliver N. , Jones Mark R. K. , Lane Peter W. , Anderson Julie
Published: January 2007

Recurrent events in clinical trials have typically been analysed using either a multiple time‐to‐event method or a direct approach based on the distribution of the number of events. An area of application for these methods is exacerbation data from respiratory clinical trials. The different approaches to the analysis and the issues involved are illustrated for a large trial (n = 1465) in chronic obstructive pulmonary disease (COPD). For exacerbation rates, clinical interest centres on a direct comparison of rates for each treatment which favours the distribution‐based analysis, rather than a time‐to‐event approach. Poisson regression has often been employed and has recently been recommended as the appropriate method of analysis for COPD exacerbations but the key assumptions often appear unreasonable for this analysis. By contrast use of a negative binomial model which corresponds to assuming a separate Poisson parameter for each subject offers a more appealing approach. Non‐parametric methods avoid some of the assumptions required by these models, but do not provide appropriate estimates of treatment effects because of the discrete and bounded nature of the data. Copyright © 2007 John Wiley & Sons, Ltd.
Social disability in different mental disorders
Authors: Rymaszewska J. , Jarosz-Nowak J. , Kiejna A. , Kallert T. , Schützwohl M. , Priebe S. , Wright D. , Nawka P. , Raboch J.
Published: January 2007

Objective

To assess the social disability of people with different psychiatric disorders.

Methods

Cross-site survey in five psychiatric hospitals (Dresden, Wrocław, London, Michalovce and Prague). Working-aged patients diagnosed (ICD-10) with schizophrenia and related disorders (F2), affective disorders (F3), anxiety disorders (F4), eating disorders (F5) and personality disorders (F6), were assessed at admission (n = 969) and 3 months after discharge (n = 753) using the Brief Psychiatric Rating Scale and the Groningen Social Disability Schedule. The main outcome measure was Interviewer-rated social disability.

Results

During acute episodes patients with personality, eating and schizophrenic disorders functioned less effectively than those with affective or anxiety disorders. After controlling for age and severity of psychopathology, there was no significant effect of the diagnosis (during remission), sex, education and history of disorder on disability. Site, employment and partnership were significant factors for the level of social disability in both measure points.

Conclusion

Severity of psychopathological symptoms, not the diagnosis of a mental disorder, was the most significant factor in determining the level of social functioning, particularly during the remission period. Site, employment and partnership appeared as significant factors influencing the level of social disability.
QSARs and activity predicting models for competitive inhibitors of adenosine deaminase
Authors: Sadat Hayatshahi Sayyed Hamed , Abdolmaleki Parviz , Ghiasi Mina , Safarian Shahrokh
Published: January 2007

Combinations of multiple linear regressions, genetic algorithms and artificial neural networks were utilized to develop models for seeking quantitative structure–activity relationships that correlate structural descriptors and inhibition activity of adenosine deaminase competitive inhibitors. Many quantitative descriptors were generated to express the physicochemical properties of 70 compounds with optimized structures in aqueous solution. Multiple linear regressions were used to linearly select different subsets of descriptors and develop linear models for prediction of log(k

i
). The best subset then fed artificial neural networks to develop nonlinear predictors. A committee of six hybrid models – that included genetic algorithm routines together with neural networks – was also utilized to nonlinearly select most efficient subsets of descriptors in a cross‐validation procedure for nonlinear log(k

i
) prediction. The best prediction model was found to be an 8‐3‐1 artificial neural network which was fed by the most frequently selected descriptors among these subsets. This prediction model resulted in train set root mean sum square error (RMSE) of 0.84 log(k

i
) and prediction set RMSE of 0.85 log(k

i
) (both equivalent of 0.10 in normal range of log(k

i
)) and correlation coefficient (r
2) of 0.91.
Pannexin1 is part of the pore forming unit of the P2X7 receptor death complex
Authors: Locovei Silviu , Scemes Eliana , Qiu Feng , Spray David C. , Dahl Gerhard
Published: January 2007

The purinergic receptor P2X7 is part of a complex signaling mechanism participating in a variety of physiological and pathological processes. Depending on the activation scheme, P2X7 receptors in vivo are non‐selective cation channels or form large pores that can mediate apoptotic cell death. Expression of P2X7R in Xenopus oocytes results exclusively in formation of a non‐selective cation channel. However, here we show that co‐expression of P2X7R with pannexin1 in oocytes leads to the complex response seen in many mammalian cells, including cell death with prolonged ATP application. While the cation channel activity is resistant to carbenoxolone treatment, this gap junction and hemichannel blocking drug suppressed the currents induced by ATP in pannexin1/P2X7R co‐expressing cells. Thus, pannexin1 appears to be the molecular substrate for the permeabilization pore (or death receptor channel) recruited into the P2X7R signaling complex.
Prostaglandin E receptor EP4 antagonist suppresses osteolysis due to bone metastasis of mouse malignant melanoma cells
Authors: Takita Morichika , Inada Masaki , Maruyama Takayuki , Miyaura Chisato
Published: January 2007

We examined the effects of prostaglandin E (PGE) receptor subtype EP4 antagonist on bone metastasis of cancer to clarify PGE's role in bone metastasis. Metastatic regions were detected in femurs accompanying severe bone loss in mice injected with B16 malignant melanoma cells. Administration of EP4 antagonist restored the bone loss induced by B16 melanoma. Adding B16 cells induced osteoclast formation in the coculture of bone marrow cells and osteoblasts without any exogenous bone‐resorbing factor, and EP4 antagonist completely suppressed the osteoclast formation induced by B16 cells. Therefore, EP4 antagonist is a possible candidate for the therapy of bone metastasis of cancer.
Uncoupling of 3T3‐L1 gene expression from lipid accumulation during adipogenesis
Authors: Temple Karla A. , Basko Xheni , Allison Margaret B. , Brady Matthew J.
Published: January 2007

Adipocyte differentiation comprises altered gene expression and increased triglyceride storage. To investigate the interdependency of these two events, 3T3‐L1 cells were differentiated in the presence of glucose or pyruvate. All adipocytic proteins examined were similarly increased between the two conditions. In contrast, 3T3‐L1 adipocytes differentiated with glucose exhibited significant lipid accumulation, which was largely suppressed in the presence of pyruvate. Subsequent addition of glucose to the latter cells restored lipid accumulation and acute rates of insulin‐stimulated lipogenesis. These data indicate that extracellular energy is required for induction of adipocytic proteins, while only glucose sustained the parallel increase in triglyceride storage.
Deletion of a MFS transporter‐like gene in Cercospora nicotianae reduces cercosporin toxin accumulation and fungal virulence
Authors: Choquer Mathias , Lee Miin-Huey , Bau Huey-Jiunn , Chung Kuang-Ren
Published: January 2007

Many phytopathogenic Cercospora species produce a host‐nonselective polyketide toxin, called cercosporin, whose toxicity exclusively relies on the generation of reactive oxygen species. Here, we describe a Cercospora nicotianae CTB4 gene that encodes a putative membrane transporter and provide genetic evidence to support its role in cercosporin accumulation. The predicted CTB4 polypeptide has 12 transmembrane segments with four conserved motifs and has considerable similarity to a wide range of transporters belonging to the major facilitator superfamily (MFS). Disruption of the CTB4 gene resulted in a mutant that displayed a drastic reduction of cercosporin production and accumulation of an unknown brown pigment. Cercosporin was detected largely from fungal hyphae of ctb4 disruptants, but not from the surrounding medium, suggesting that the mutants were defective in both cercosporin biosynthesis and secretion. Cercosporin purified from the ctb4 disruptants exhibited toxicity to tobacco suspension cells, insignificantly different from wild‐type, whereas the disruptants formed fewer lesions on tobacco leaves. The ctb4 null mutants retained normal resistance to cercosporin and other singlet oxygen‐generating photosensitizers, indistinguishable from the parental strain. Transformation of a functional CTB4 clone into a ctb4 null mutant fully revived cercosporin production. Thus, we propose that the CTB4 gene encodes a putative MFS transporter responsible for secretion and accumulation of cercosporin.
A simple method to rule out dementia with temporal orientation
Authors: Tractenberg Rochelle E. , Weiner Myron F. , Aisen Paul S. , Kaye Jeffrey A. , Fuh Jong-Ling
Published: January 2007

Objective

To explore the performance of a test of temporal orientation (TTO) comprising four items derived from the Mini‐Mental State Examination over 4 years.

Methods

Responses were obtained from two large cohorts participating in longitudinal studies of aging in the United States (352 normal elderly, 98 persons with very mild probable or possible Alzheimer's disease). Sensitivity, specificity, and predictive value (positive, PV+, negative, PV−) of the TTO were estimated for each of four annual visits.

Results

When four correct answers were treated as “oriented to time” and 0 to 3 correct answers were treated as “not oriented to time,” sensitivity (to the presence of AD) ranged from 46.0% to 69.2% and PV+ ranged from 32.1% to 49.5%. Specificity (for normal cognition) decreased from 93.2% at the first visit to 81.3% at the fourth visit; TTO performed most reliably in terms of PV−, the probability of normal cognitive function given orientation to time (TTO = 4), which ranged from 92.8% to 95.4%.

Conclusion

Given the stability and strength of the predictive negative value of a dichotomized TTO over time, a TTO could contribute to monitoring normal cognitive functioning in longitudinal studies in which cognitive status is not the primary focus. Prospective validation of the TTO is warranted.
A Comparison between Subjective Outcome Score and Moderate Radial Shortening Following a Fractured Distal Radius in Patients of Mean Age 69 Years
Authors: BARTON T. , CHAMBERS C. , BANNISTER G.
Published: January 2007

Radial shortening has been associated with a poor functional outcome following a fractured distal radius. This paper reports the results of evaluation by the patient rated wrist evaluation (PRWE) score of 60 patients (mean age 69) who underwent closed reduction and K-wire fixation of distal radial fractures. In this patient group, no association was found between moderate radial shortening, either at injury or fracture union, and this subjective outcome score. A significant association was found between the assessment of these fractures by the Frykman classification and the PRWE score ( P = 0.01).
Use of Integra in a Paediatric Upper Extremity Degloving Injury
Authors: HERLIN C. , LOUHAEM D. , BIGORRE M. , DIMEGLIO A. , CAPTIER G.
Published: January 2007

Dermal substitutes such as Integra® have been used in surgery since 1981. This product was developed to cover large skin burns but it may have a role in reconstructive upper limb surgery. In upper extremity avulsion, the choice of skin cover depends on many variables. Dermal substitute is an alternative when split-thickness skin grafting is appropriate. We present a case of severe upper limb avulsion, or ‘degloving’, in a child of 9 years old which was treated successfully with Integra. Integra® is particulary useful in growing children to cover large skin losses.
Irreducible Galeazzi Fracture–Dislocation Due to Intra-Articular Fracture of the Distal Ulna
Authors: GUNES T. , ERDEM M. , SEN C.
Published: January 2007

Irreducible Galeazzi fracture–dislocation is a rare injury. Structures that mechanically block the reduction are usually soft tissues. We present an irreducible case due to distal ulnar intra-articular fracture.
Factors Affecting the Sagittal Alignment of the Lunate
Authors: GUPTA A.
Published: January 2007

The lunate is described as having a tendency to rotate dorsally as a result of its wedge shape, with the apex towards the dorsum, but maintains an attitude of flexion in most individuals. The present study comprised CT scans of the wrist of 70 healthy volunteers. Sagittal measurements were drawn for the midcarpal and radiocarpal axes, alignment and various shape patterns of the lunate. The midcarpal axis was found to be dorsal, volar and collinear to the radiocarpal axis in 21 (30%), 29 (41%) and 20 (29%) subjects, respectively. The sagittal alignment of the lunate demonstrated significant correlation with measurements of the midcarpal and radiocarpal axes with no correlation with its various shape patterns. It is concluded that the relationship between the midcarpal axis and the radiocarpal axis in terms of dorsovolar displacement has a key role in determining the sagittal alignment of the lunate, while the shape of the lunate may be only a secondary consideration
What to Do When a Loved One Dies: A Practical and Compassionate Guide to Dealing with Death on Life's Terms
Authors: Pashley Helen Starbuck
Published: January 2007

What to Do When a Loved One Dies: A Practical and Compassionate Guide to Dealing with Death on Life's Terms second ed Eva Shaw 2005, 365 pages $24.95 softcover
Partnering With Patients to Reduce Medical Errors
Authors: Battalora Elizabeth
Published: January 2007

Partnering With Patients to Reduce Medical Errors Patrice L. Spath, ed 2004, 198 pages $45 AORN members special price/$75 nonmembers hardcover
LITIGATION MASTERS AND THE LITIGATION SYSTEM OF MING AND QING CHINA
Authors: Fuma Susumu
Published: January 2007

Litigation masters (songshi), who flourished in traditional China, have long been associated in the minds of the public with questionable legal behaviour, taking advantage of the lack of legal know-how of plaintiffs. Though they existed outside the law and their existence was constantly castigated by the authorities, they played a very important role in society. This article examine the reality of what it meant for ordinary people to go to law, in an attempt to reassess how the litigation system actually worked, as opposed to how it was described ideally by the state. It first looks at litigation procedures and the trial process, and concludes that the Chinese were extremely litigious, challenging the notion that people preferred to resolve disputes by mediation rather than by going to court. Court procedures were complicated and costs high, and not all plaints submitted to the court were accepted. To ensure that the correct forms were followed, expert help was necessary, and this help often took the form of the litigation master. He acted as proxy for litigants, for he was unable to appear in court in person, and he played a vital role in negotiating with the lower court functionaries whose support was vital for the success of a case. He also wrote plaints in a form acceptable to the courts, and coached litigants in their presentation. The litigation master was often a former civil service examination candidate, and so trained in the kind of writing skills the court required. Failed students often had to choose between becoming a private secretary to a magistrate or a litigation master, and there was a continuum between the two. Thus it was the examination system itself that fostered litigation masters. Because the state refused to recognize litigiousness, it also had to refuse to recognize the lawful existence of litigation masters. Nevertheless they met an important social need.
Wirksamkeit und Kosten einer kontinuierlichen Langzeitbehandlung mit Esomeprazol versus einer Anwendung bei Bedarf bei symptomatischen Reflux-Patienten in der Praxis ohne endoskopische Abklärung – die ONE Studie (On-demand Nexium® Evaluation)
Authors: Beglinger  , Thalmann  , Szucs  , Michetti
Published: January 2007

Zwei Behandlungsstrategien mit Esomeprazol 20 mg – kontinuierliche tägliche Gabe oder Einnahme bei Bedarf – zur Langzeitbehandlung von Patienten, die ihren Hausarzt wegen symptomatischer gastroösophagealer Refluxkrankheit (GERD) aufsuchten, wurden in der ONE Studie (On-demand Nexium® Evaluation) verglichen. Alle Patienten erhielten eine Initialbehandlung (ohne endoskopische Abklärung) mit Esomeprazol 40 mg, einmal täglich, während vier Wochen. Bei Symptomfreiheit wurden die Patienten in einen der beiden Studienarme randomisiert. Total wurden 1904 Patienten randomisiert, 913 Patienten erhielten während 26 Wochen eine kontinuierliche Therapie mit Esomeprazol 20 mg, einmal täglich, und 991 Patienten nahmen Esomeprazol 20 mg bei Bedarf ein. Die kontinuierliche Therapie zeigte eine geringfügig bessere Befreiung vom Symptom Sodbrennen, während die Einnahme bei Bedarf mit tieferen direkten medizinischen Kosten verbunden war. Esomeprazol war allgemein gut verträglich.
Developmental Progression in Children’s Strategic Memory Regulation
Authors: Roebers Claudia M.
Published: January 2007

A developmental study was conducted that investigated 7- to 11- years-olds’ ability to strategically regulate their memory performance. The study, based on Koriat and Goldsmith’s (1996) theoretical framework, sought to stimulate strategic regulation processes. In order to do so, the threshold to provide or withhold answers was manipulated and included bonuses for correct responding and penalties for incorrect answers. Participants were shown a video concerning the production of sugar from beets and were individually interviewed a week later. Responses had to be made to both answerable and unanswerable questions in both an open-ended and a yes/no question format. The results revealed that depending on the question format, there were different effects of the threshold manipulations on the frequencies of correct, incorrect, and “I don’t know” responses. Although there were no differences in response behaviour between the 1:0 and 1:1 incentives conditions when the questions were open-ended, children were able to differentially respond to the two bonus-to-penalty ratios when the questions were in yes/no format. Consistently, there were no interactions between age and response threshold indicating that strategic regulation competencies develop slowly but continuously during the primary school years showing the first signs of emerging competencies from an age of 7 onwards.