bluuebunny/crossref_metadata_2025 huggingface dataset:
p53 and DPC4 alterations in the bile of patients with pancreatic carcinoma
Authors: Pantalone Desiree , Pelo Elisbetta , Minuti Barbara , Giotti Irene , Mazza Ernesto , Falchini Massimo , Neri Bruno , Nesi Gabriella , Roberta Girardi Lucia , Pulli Raffaele , Credi Giovanni , Torricelli Francesca
Published: November 2004

Introduction

Pancreatic cancer is still predominantly diagnosed in advanced stages, and 85%–90% of patients are not eligible for surgery at diagnosis. This is mainly due to the great difficulty in detecting the tumour at an early stage and presently no satisfactory results have been obtained to overcome this problem. Studies on molecular genetic profile of pancreatic cancer may represent an important approach. This study was focused on the mutations of p53 and DPC4 detectable in the bile of patients with histologically proven pancreatic cancers.

Materials and Patients

We analysed specimens of bile collected through percutaneous transhepatic biliary catheters, placed to treat malignant biliary obstruction in 25 patients with pancreatic adenocarcinoma. A percentage of mutation was obtained of 43 % for the microsatellite D17S945 (p53), 54% and 50 % for D18S46 and D18S474 (DPC4), respectively. The percentage of amplification was 67%, 93,6%, and 80%.

Conclusion

We consider the results encouraging enough to decide to enlarge the number of patients examined. The aim is to determine if a test for DPC4 and p53 mutations is eligible for introduction in clinical routine use. More sets of samples are required to satisfactorily answer this question. J. Surg. Oncol. 2004;88:210–216. © 2004 Wiley‐Liss, Inc.
Two colons‐two cancers: Paradigm shift and clinical implications
Authors: Gervaz Pascal , Bucher Pascal , Morel Philippe
Published: November 2004

Embryological and physiological data suggest that proximal (in relation to the splenic flexure) and distal parts of the colon represent distinct anatomical and functional entities. Since 1990, molecular biologists have identified two distinct pathways, microsatellite instability (MSI) and chromosomal instability (CIN), which are involved in the pathogenesis of colon cancer (CC). Thus, a new paradigm has emerged with the discovery that CC is a heterogeneous disease; furthermore recent data have demonstrated that these two distinct pathways in colorectal carcinogenesis are characterized by a different clinical outcome. The implications for the clinicians are twofold; (1) tumors originating from the proximal colon have a better prognosis due to a high percentage of MSI‐positive lesions; and (2) location of the neoplasm in reference to the splenic flexure should be documented before group stratification in ongoing trials of adjuvant chemotherapy for CC. In the future, clinical decision‐making regarding adjuvant chemotherapy might be stratified according to the MSI status of cancers located proximally to the splenic flexure. J. Surg. Oncol. 2004;88:261–266. © 2004 Wiley‐Liss, Inc.
Hepatic arterial catheterization combining interventional radiological and laparotomic approaches
Authors: Watanabe Masashi , Takita Wataru , Nakazaki Haruhiro , Tanemura Hiroyuki , Kaneko Hironori , Kobayashi Kazuo
Published: November 2004

Background and Objectives

This report describes a modified method of implanting a catheter‐port system for hepatic arterial infusion chemotherapy (HAIC) that combines interventional radiological (IVR) and laparotomic approaches.

Methods and Results

In patients, scheduled for HAIC and laparotomic surgery, we now employ a modified method of implanting the catheter‐port system. In our method, an IVR approach is used to implant the catheter‐port, and arterial occlusions are primarily carried out using a laparotomic approach. Following celiac and superior mesenteric arteriographies, a tapered microcatheter with a side hole is inserted by a catheter exchange method. The catheter tip is advanced far into the gastroepiploic artery via the gastroduodenal artery (GDA). The side hole is located at the orifice of the proper hepatic artery, and its location is confirmed by injection of contrast media. The microcatheter is connected to the port, and the port is buried in the subcutaneous pocket. During the laparotomy stage, the GDA lumen and the catheter lumen are clipped, and the right gastric artery (RGA) and all small branches supplying the stomach, duodenum, and pancreas are ligated. Among the 13 patients successfully implanted with a port‐catheter system using our combined approach, no patients had hepatic artery occlusion or occlusion of the catheter system.

Conclusions

Initial results from a study of a new method of implanting a microcatheter‐port system in the hepatic artery using combined IVR and laparotomic approaches suggest that this method may enable operators to avoid complicated selective coiling and may lower the incidence of hepatic artery occlusion in patients receiving long‐term HAIC. J. Surg. Oncol. 2004;88:256–260. © 2004 Wiley‐Liss, Inc.
X‐Ray and Electron Diffraction Study of Poly(p‐dioxanone)
Authors: Furuhashi Yukiko , Nakayama Atsushi , Monno Teruo , Kawahara Yutaka , Yamane Hideki , Kimura Yoshiharu , Iwata Tadahisa
Published: November 2004

Summary: Solution‐grown lamellar crystals of poly(p‐dioxanone) (PPDX) have been crystallized isothermally from butane‐1,4‐diol at 100 °C. The crystal structure of PPDX has been determined by interpretation of X‐ray fiber diagrams of PPDX fibers and electron diffraction diagrams of lozenge‐shaped chain‐folder lamellar crystals. The unit cell of PPDX is orthorhombic with space group P212121 and parameters: a = 0.970 nm, b = 0.742 nm, and c (chain axis) = 0.682 nm. There are two chains per unit cell, which exist in an antiparallel arrangement.

Transmission electron micrograph of PPDX chain‐folded lamellar crystals obtained by isothermal crystallization and its electron diffraction diagram.

image

Transmission electron micrograph of PPDX chain‐folded lamellar crystals obtained by isothermal crystallization and its electron diffraction diagram.
Einfluß stochastischer Erregungen auf das Verhalten der Querdynamik eines Eisenbahnradsatzes
Authors: Cichon Martin , Wedig Walter
Published: November 2004

Der Eisenbahnradsatz spielt in der Systemdynamik der Eisenbahnfahrzeuge aufgrund seiner außerordentlich hohen Beanspruchung und seiner absoluten Sicherheitsrelevanz die zentrale Rolle. Als passives Bauelement sorgt er f ür das Tragen, Führen und Antreiben bzw. Bremsen des Fahrzeugs. Die Querdynamik beschäftigt sich mit dem Führen des Radsatzes im Gleis innerhalb des vorgegebenen Spurspiels.

Wie alle technischen Gebilde ist auch das Gleis und der Radsatz nicht frei von Abweichungen zu einem definierten Sollzustand. Das hinsichtlich der Querdynamik in Betracht gezogene vereinfachte Modell berücksichtigt lediglich Gleislagefehler und hierbei zunächst nur den Gleisquerlagefehler.

Für ein stark vereinfachtes Modell zur Untersuchung der Radprofilpaarung unter dem Einfluß einer weißen Rauschanregung ist das invariante Maß durch Lösung der zugehörigen Fokker‐Planck‐Kolmogorow‐Gleichung analytisch geschlossen angebbar. Mittels Monte‐Carlo Simulationen läßt sich das Querdynamikverhalten komplizierterer Systeme und der Realität angepaßter Anregungen besser untersuchen. Zur Anregung werden Filter benötigt, die Trajektorien mit gleichen statistischen Eigenschaften erzeugen, wie sie bei realen Gleisen auftreten.

Die gewonnenen Ergebnisse werden diskutiert und mit Messungen verglichen. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Brake vibrations at very low driving velocities
Authors: Hetzler H. , Seemann W.
Published: November 2004

Vibrations in vehicle brake systems have been subject to research for a long time. One simple phenomenological model ist the classical friction oscillator, consisting of a mass on a belt. A closer look to a real brake system reveals that from the tyre's contact on the street to the disc the brake torque is transmitted via the tyre, which also possesses elastic, dissipative and inertial properties. Motivated by this fact an extended 2‐DOF friction oscillator model is developed featuring the rim's inertia and the dissipative and elastic behaviour of the tyre. In this article the model is given and simulation results are presented. It is found, that additional torsional elasticity und damping can induce very low frequent vibrations. In addition an outlook on further studies is given. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rauheitseinfluss auf die Adhäsion von Elastomeren
Authors: Kröger Matthias
Published: November 2004

Im Kontakt zwischen einem Elastomer und einem rauen Reibpartner wird Reibung durch Hysterese‐ und durch Adhäsioneffekte verursacht. Mit dem hier vorgestellten Adhäsionspendel werden die Hysterese‐ und Adhäsionsverluste beim Aufprall und beim Trennen einer flächigen Elastomerprobe im radialen Kontakt zu einem Zylinder untersucht. Die Rauheit des Kontaktpartners wird durch Bekleben des Zylinders mit Schmirgelpapier variiert. Es zeigt sich, dass auf Schmirgelpapier der Adhäsionseffekt kleiner ist als auf einer geschliffenen Stahloberfläche. Die Adhäsion besitzt aber immer noch nennenswerten Einfluss auf den gesamten Energieverlust. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Dynamics of Bundled Conductors in Overhead Transmission Lines
Authors: Verma Himanshu , Dighe Ashish M. , Hagedorn Peter
Published: November 2004

The Energy Balance Principle (EBP) is well established for estimating the vibration levels of wind induced oscillations of single overhead transmission lines. The mathematical model, wherein a conductor is treated as a continuous system, results in a transcendental eigenvalue problem (EVP), which gives numerical difficulties in the case of bundled conductors. In this paper, different approaches for solving transcendental EVP and their relative merits are discussed. A new method named continuous spectrum approach provides a good engineering solution. Results from different approaches are compared. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectral projectors and their applications in structural dynamics
Authors: Wagner N.
Published: November 2004

Spectral projectors exhibit some powerful properties. For example, the trace of a spectral projector can be used to determine the number of eigenvalues enclosed by a curve. Here some other nice features of spectral projectors are investigated. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vibrations of Piezoceramic Rods
Authors: Wauer Jörg
Published: November 2004

Presently, most of the research on vibrations of monolithic piezoelectric rods at weak electric fields is restricted to longitudinal oscillations of such structural members where free and forced vibrations have been dealt with and in the case of resonance conditions not only linear but also nonlinear effects within the constitutive relations have been incorporated. On the other hand, bending and torsional vibrations of piezoceramic one‐parametric rods have not been examined yet. The present contribution develops a linear vibration theory of rods with a focus to bending vibrations taking into account rotatory inertia and shear deformation. The governing boundary value problem for beams with both longitudinal and as well transversal polarization is derived, in particular free vibrations are analyzed. Also nonlinear extensions not only of physical nature but also geometrical ones are addressed. A possible technical application is given. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis of virtual measurements in nonlinear observation problem
Authors: Shcherbak V. F.
Published: November 2004

The method of the observation problems reducing to the algebraic ones is considered for the systems, which are linear with respect to unknown components of the phase vector. The approach proposed is based on the methods of the controlled stabilization of nonlinear system with respect to the part of variables. The equations of the initial observable system are supplemented by the equations of its controlled prototype. Then control law synthesied in such way that any given manifold becomes an invariant for extended system. For ensuring of this manifold attracting property the partial differential equations are obtained. Finally, the chosen in such way algebraic relations are considered as additional virtual measurements of unknown state. As example the problem of the angular velocity determination of a rigid body is considered. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multibody Dynamics of Cargo Airships During the Load Exchange Process
Authors: Bockstedte Andreas , Kreuzer Edwin
Published: November 2004

Projected cargo airships for the flexible transport of large loads exceed the dimensions of existing aircrafts and gave rise to various technical problems.

In order to study the dynamics of the load exchange process mathematical models of the airship including the oscillating load frame are developed. The hull and the load frame are represented by a multibody system. Crucial aspects contributing to the system's dynamics are the floatation of the flying crane and nonlinear couplings between hull and load frame.

Furthermore, added masses of the surrounding air are considered. Oscillations of the load frame are excited by wind loads, airship maneuvers, and winding up the cables. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of flexible link manipulators
Authors: Mladenova Clementina , Rashkov Ivan
Published: November 2004

The purpose of this work is to present a method for symbolic generation of the dynamic equations within the Hamiltonian formalism of flexible robots with open‐chain linkage mechanisms using the so‐called vector‐parameterization of the SO(3) group as it is quite effective for many rotational degrees‐of‐freedom. The both, an exact treatment and approximated model of the differential equations of motion are considered. The authors step on their long experience of using the vector‐parameterization for modelling of rigid body mechanical systems. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Studies Regarding the Alternate Simulation Techniques for Machine Toolsand Industrial Robots
Authors: Pisla A. , Pisla D.
Published: November 2004

In the paper are presented results regarding the design, simulation and testing of some robotized structures with parallel kinematics in order to identify appropriate simulation techniques and to reveal the properties of particular studied characteristics. The paper is structured in three parts: introduction regarding the tasks of the simulations techniques and the developed applications, comparison of the results obtained in simulations, considering the working space modelling accuracy and the speed of workspace identification and the last part conclusions. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling and Mechanical Design of Underactuated Robot Manipulators with Impact and Friction
Authors: Welge‐Luessen Tobias
Published: November 2004

This paper provides a theoretical approach for describing underactuated mechanical systems and conceptual ideas for the design of an underactuated robot manipulator. The mathematical description uses the Linear Complementarity Problem (LCP) formulation in order to handle the equations of motion with inequality constraints. The robot manipulator serves later on as an experimental platform for the verification of control strategies of underactuated systems and the exploration of underactuated walking patterns. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Thermomechanical Model for a Class of Hyperelastic Materials with Viscoelastic Properties of a Single‐Integral Type
Authors: Dobovšek Igor
Published: November 2004

To incorporate the strain rate dependence and strain memory properties in the constitutive formulation, we introduce integral hereditary operators of Volterra type in place of free material constants of a general hyper stress constitutive model. The corresponding constitutive equations, which are derived from the proposed form of a free energy functional, are based on a single‐integral type representation of the response functionals inherent in the expression for free energy. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Konstitutive Modellierung der Anisotropie in kalandrierten Gummib
Authors: Ehret Alexander , Itskov Mikhail , Aksel Nuri
Published: November 2004

In Experimenten weisen kalandrierte Gummibänder eine transversale Isotropie hinsichtlich der Kalandrierrichtung auf [1]. Fig. 1 zeigt den Unterschied in den Nominalspannungen zwischen Kalandrier‐ und Transversalrichtung und macht deutlich, dass diese Anisotropie bei der konstitutiven Modellierung berücksichtigt werden sollte. Zu diesem Zweck werden hier zwei hyperelastische Modelle vorgeschlagen. Das erste Modell ist vom St. Venant‐Kirchhoff‐Modell abgeleitet [2] und nicht polykonvex. Polykonvexität stellt jedoch nicht nur Elliptizität und damit die Legendre‐Hadamard‐Beziehung sicher, sondern garantiert zusammen mit der Koerzivität auch die Existenz einer Deformation, die die gesamte elastische Energie des Körpers global minimiert. Dies ist insbesondere bei der Lösung von Randwertproblemen von Bedeutung. Das zweite Modell basiert daher auf einer polykonvexen Verzerrungsenergiefunktion [3]. Beide Verzerrungsenergiefunktionen werden durch Potenzreihen mit beliebig vielen Termen und einer entsprechenden Zahl an Materialparametern approximiert. Mit Hilfe der Methode der kleinsten Fehlerquadrate werden diese Modelle an experimentelle Daten angepasst. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A cohesive element approach for viscoelastic interface properties
Authors: Geissler Gordon , Kaliske Michael
Published: November 2004

This paper introduces a time dependent extension of the nonlinear traction separation law for an interface element. The constitutive equations of the load history dependent behaviour of the material are depicted and derived according to a generalized Maxwell‐model. This finite linear, viscoelastic approach allows the consideration of long term loading and time dependent material behaviour in thin layers. The implementation of the presented element formulation and the material approach are verified by numerical examples. The paper gives an outlook on further work and research topics. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the rail pad on a vehicle travelling on a straight track
Authors: Gerstberger Ulf , Knothe Klaus , Rücker Werner
Published: November 2004

In the following text, the influence of the stiffness of rail fastening systems of high‐speed railway lines on the dynamic stability of a vehicle travelling along a straight track is investigated. The dynamic behaviour of the rail head in lateral direction is incorporated in the model by means of mechanical models derivedfrom a preceding frequency analysis of the track. For the wheel‐rail interface, linear contact mechanics and kinematic relations are applied. The investigation leads to the conclusion that on high‐speed lines the critical velocity of vehicles is reduced as a result of the increased elasticity of the rail pads. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reibungsinduzierte thermoelastische Instabilitäten von Kreisringplatten
Authors: Krempaszky Christian , Werner Ewald , Lippmann Horst
Published: November 2004

In diesem Beitrag wird auf Basis der Kirchhoffschen Plattentheorie ein Modell zur Beschreibung der reibungsinduzierten thermoelastischen Instabilitäten (TEI) in Kreisringplatten erstellt. Die Hauptaufgabe besteht in der Formulierung der thermomechanischen Rückkopplung des Reibkontakts. Mit dem resultierenden Eigenwertproblem lassen sich die kritischen Betriebszustände abschätzen. Als Anwendungsbeispiel wird das Scheibenpaket einer Mehrscheibenkupplung betrachtet. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A 3‐level discretisation strategy using substructuring
Authors: Rickelt Christian , Schwarze Marco , Reese Stefanie
Published: November 2004

This contribution deals with a new three‐level discretisation strategy which enables to discretise a structure according to the required modelling accuracy. Correspondingly the structure is separated into a continuum, a structural and a black box model level. This note especially focuses on the transitions between continuum‐structure and structure‐substitute model. The first one is realised by means of a model adaptive concept based on the innovative finite element technology of the Q1SP family. The latter is carried out by an enhanced modal reduction method which is combined with a novel substructure technique. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inplane Stress Singularities at the Corner of an Anisotropic Material Discontinuity
Authors: Wigger Hubertus Michael , Becker Wilfried
Published: November 2004

In the mechanics of composite laminates the local mechanical inplane fields at corners of anisotropic material discontinuities are of particular interest since they can have singular behavior. In the present study, the stress and strain fields in the local near field of such corners are investigated by an asymptotic analysis. The order of the singularity of these mechanical inplane fields are determined in closed‐form manner by use of the complex potential method based on Lekhnitskii's approach. Various different geometrical setups and material combinations of corners with material discontinuities are investigated with regard to their effect on the singular behavior of the mechanical fields present. These examples show that the order of singularity considered is clearly weaker than the typical crack tip singularity in fracture mechanics. Nevertheless, it may render the corner a critical location for the onset of failure. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical simulation of microstructures via higher‐order rank‐one relaxation
Authors: Hoppe Ulrich , Hackl Klaus
Published: November 2004

Calculation of inelastic material behaviour by means of relaxation algorithms provides an effective way to deal with fine‐scale microstructures resulting from non‐quasiconvex potentials. Especially the rank‐one relaxation admits a straight forward algorithmical realization and results in valuable information that enables the reconstruction of the underlying microstructure. This article is concerned with the application of higher–order rank–one relaxation to a single–slip plasticity model and focusses especially on the numerical algorithm. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reine Scherung mit rotierenden Achsen
Authors: Besdo D. , Hohl C. , Ihlemann J.
Published: November 2004

Bei der Entwicklung komplexer Stoffgesetze und bei deren Anpassung an konkrete Materialien spielen die experimentelle Realisierung und die Simulation homogener Belastungs‐ und Verformungsprozesse eine entscheidende Rolle, da diese das reine Materialverhalten widerspiegeln. Für die Formulierung der jeweiligen Randbedingungen bieten sich bei verschiedenen Prozessen unterschiedliche Spannungs‐ und Deformationsmaße an. Als ein mit herkömmlichen Algorithmen besonders schwer zu erfassendes Beispiel wird die reine Scherung mit rotierenden Achsen vorgestellt. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ellipsoidrepräsentation von Anisotropietensoren
Authors: Besdo D. , Ihlemann J.
Published: November 2004

Bei vielen Werkstoffen, deren mechanisches Verhalten langfristig von der Belastungsvorgeschichte beeinflußt wird, ist dieser Einfluß mit einer ausgeprgten induzierten Anisotropie verbunden. Während sich für die Modellierung isotroper Materialver änderungen im Idealfall ein einzelnes skalares Maß als ausreichend erweist, sind f ür die Beschreibung induzierter Anisotropie tensorielle Größen erforderlich. Häufig sind hierfür Tensoren 4. Stufe nötig [1]. In einfacheren Fällen erlaubt die Ellipsoidrepräsentation von Tensoren 2. Stufe einen anschaulichen Zugang zu deren Verwendung als Anisotropietensoren. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of nonlinear properties of ferroelectric and piezoceramicmaterials
Authors: Delibas Bülent , Arockiarajan Arunachalakasi , Seemann Wolfgang
Published: November 2004

Ferroelectric and piezoelectric materials are becoming a very significant part of smart materials that are used widely as actuators, sensors and most common applications such as vibration control, precision positioning, precision cutting and microelectromechanical systems (MEMS). Piezoceramic materials show nonlinear characteristics when they are under high electromechanical loading. In this study, nonlinear behaviour of tetragonal perovskite type piezoceramic materials is simulated using micromechanical model. In the simulations uni‐axial loading is applied. The calculations which are based on a linear constitutive model, nonlinear domain switching model and a model of probability to switch are performed at each grain. The different domain switching effects (900 or 1800 domain switching for tetragonal perovskite structure) due to energy differences, different probability functions, different statistical random generators and material parameters are analyzed. Finally, simulation results are compared with the data of experiments are giving in literature. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐ and nanoscale modelling of dry friction with application to the wheel/rail contact
Authors: Ertz M. , Knothe K. , Popov V. L. , Psakhie S. G.
Published: November 2004

Friction is a phenomenon involving elastic interactions, plastic deformation and failure processes at different length scales. A model of dry friction is established based on the method of Movable Cellular Automata (MCA). The influence of material and loading parameters has been investigated within a large number of numerical simulations. The new friction law is applied to the calculation of stresses, deformations and tractive forces in wheel/rail contact with rough surfaces. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The theoretical treatment of cooling processes in porous rocket thrustchambers
Authors: Ghadiani Said , Ehlers Wolfgang
Published: November 2004

One of the most promising approaches for future high pressure rocket combustion chambers is the application of porous carbon fiber reinforced ceramics in conjunction with the effusion cooling in fluid‐cooled rocket engines. In order to determine the coolant mass flow through the porous material, the influences of the temperature have to be taken into account additionally. Thus, one has to deal with interacting continua governed by non‐isothermal processes, when designing a porous rocket combustion chamber for realistic operating conditions such as extremely high temperatures. Describing coupled solid‐fluid problems efficiently, it is generally convenient to utilize macroscopic strategies like the Theory of Porous Media (TPM). While in the past, most of the multiphase problems based on the TPM have been treated isothermally, the present contribution extends the theoretical treatment to non‐isothermal problems. This is achieved by proceeding from a thermoelastic solid skeleton saturated by a compressible viscous pore‐fluid, whereas a separate temperature field has to be established for each constituent. Finally, the efficiency of the developed model will be briefly discussed by computing some simple non‐isothermal physical effects, which are solved by the FE tool PANDAS. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modellierung der pseudoelastischen Materialeigenschaften von Formgedächtnislegierungen
Authors: Helm Dirk
Published: November 2004

Die pseudoelastischen Materialeigenschaften von Formgedächtnislegierungen werden unter anderem im Bereich der Medizintechnik eingesetzt (vgl. [1]). In dem Artikel wird ein Materialmodell zur Beschreibung der Pseudoelastizität vorgestellt (vgl. [2]). Das Materialmodell basiert auf einer Materialfunktion für die Freie Energie sowie Evolutionsgleichungen für Innere Variable. Die Energiefunktion beschreibt dabei Energiespeicherungsvorgänge aufgrund der Thermoelastizität, der Energiedifferenz zwischen den beiden betrachteten Phasen (Austenit und Martensit) sowie die Energiespeicherung infolge der Entwicklung von Inneren Spannungen. Das System der Konstitutivgleichungen erfüllt den 2. Hauptsatz der Thermodynamik in Form der Clausius‐Duhem Ungleichung. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the effect of cell irregularity on the effective behavior of solid foams
Authors: Hohe Jörg , Becker Wilfried
Published: November 2004

The present study provides an analytical probabilistic approach for the homogenization of hyperelastic solid foams with irregular microstructure. The scheme is based on the multiple analysis of a randomized representative volume element in conjunction with a stochastic evaluation of the results in terms of the stress mean values and the corresponding standard deviations defining the scatter band widths. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Konstitutives Modellieren von Fichtenholz unter biaxialer Beanspruchung mittels eines orthotropen Einflächenmodells unter Berücksichtigung von Ver‐ und Entfestigung
Authors: Müllner Herbert Wolfgang , Eberhardsteiner Josef , Mackenzie‐Helnwein Peter
Published: November 2004

In diesem Beitrag wird über die Entwicklung eines Einflächen‐Plastizitätsmodells für fehlerfreies Fichtenholz unter biaxialen Beanspruchungszuständen berichtet. Zur Beschreibung des elasto‐plastischen Materialverhaltens wurde eine elliptische Fließfläche nach [5] herangezogen, dessen Form mittels einer nicht‐assoziierten Ver‐ und Entfestigungsregel gesteuert wird. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the stabilization mechanisms in liquid metallic foams
Authors: Wübben Th. , Odenbach S.
Published: November 2004

Metal foams are porous structures made up of conventional metals such as aluminium. Their advantageous density to stiffness ratio leads to a variety of applications especially in automotive industry, where they have gained interest as material used in shock absorbers and light weight construction parts.

Solid metal foams are usually produced by solidification of a liquid metallic foam. The latter is generated by the introduction of gas into a melt analogous to aqueous foams. Depending on the parameters of the production process, porous structures with relative densities down to 10% of the original metal can be achieved. However, while the mechanisms leading to stable aqueous foams are quite well understood, this is not the case for metallic foams. In contrast for example to soap foams, no surface active or polar substances are present in liquid metals. It is merely known empirically that solid particles have a major influence on the stability of a liquid metallic foam.

In this paper we present experimental observations showing that the stability and structure of metallic foams produced via a melt route are predominantly governed by interface rather than drainage effects. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Higher order continuum models for cellular materials including damage
Authors: Ebinger Tobias , Steeb Holger , Diebels Stefan
Published: November 2004

An extended continuum‐mechanical model for the description of the deformation behavior of foam‐like structures including damage ist presented. While it is very difficult to formulate constitutive equations on the macroscale for these materials, the constitutive equations, material parameters and evolution equations including damage are assumed to be known for the beamlike microstructure. Within a finite element computation the strains and, according to the macroscopic extended continuum model, the curvatures are mapped to the integration point. Attaching a microstructure to each integration point allows for the construction of a boundary value problem for the local microstructure. After evaluation of the microscopic constitutive equations, the forces and moments are mapped back to the macroscale by a homogenization procedure yielding the stress and couple stress response. This approach is known from literature as FE2 model. The capability of the model is demonstrated in a numerical example. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the assessment of cracks within the interface of thin layers on a substrate
Authors: Müller A. , Goswami S. , Hohe J. , Becker W.
Published: November 2004

Although bimaterial wedge or notch configurations are identified as potential weak locations, the assessment of the degree of criticality of cracks in such regions is still a demanding problem. The singular character of the stress field at cracks or at bimaterial notches can be calculated analytically or numerically. The angle of the direction of potential crack initiation may also be determined, but the decisive question is whether a hypothetical crack will be initiated or not.

An essential question in the context of crack assessment is to find a criterion for crack nucleation. For that aim, the hypothesis of Leguillon is modified. Herein, the crack is assumed to be critical when and only when both the released energy and the local stress reach critical values along a hypothetical crack of finite length. This concept can be transferred to a bimaterial interface configuration of a thin layer on a substrate. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prenatal ultrasound diagnosis of a case of Pfeiffer syndrome without cloverleaf skull and review of the literature
Authors: Nazzaro Alfredo , Monica Matteo Della , Lonardo Fortunato , Blasi Arturo Di , Baffico Maria , Baldi Maurizia , Nazzaro Giovanni , Placido Giuseppe De , Scarano Gioacchino
Published: November 2004

Pfeiffer syndrome is characterized by bilateral coronal craniosynostosis, midface hypoplasia, beaked nasal tip, broad and medially deviated thumbs and great toes. Originally, it was described in eight persons from three generations in a pedigree consistent with an autosomal dominant transmission. Since then, several reports have documented its high clinical and genetic heterogeneity. The condition is usually detected in the newborn period or later, and very few prenatal ultrasound diagnoses have been reported.

We present a case of Pfeiffer syndrome prenatally diagnosed at 20 weeks' gestation, in which the sonographic features of craniosynostosis, hypertelorism associated with an extreme proptosis, and broad thumb led to the diagnosis, confirmed after termination of pregnancy by dysmorphological, pathological and radiological evaluation.

DNA analysis of the fibroblast growth factor receptor 2 (FGFR2) showed a missense mutation consisting in a transversion G → C at nucleotide 870. This led to a Trp290Cys amino acidic substitution.

We discuss the relevant findings of our and previously published cases. Our report demonstrates that a careful sonographic examination can lead to an early prenatal diagnosis of Pfeiffer syndrome also in cases without cloverleaf skull. Copyright © 2004 John Wiley & Sons, Ltd.
Placenta growth factor levels in second‐trimester maternal serum in Down syndrome pregnancy and in the prediction of preeclampsia
Authors: Lambert‐Messerlian Geralyn M. , Canick Jacob A.
Published: November 2004

Objectives

To determine the levels of placenta growth factor (PlGF) in second‐trimester maternal serum samples from pregnancies affected with fetal Down syndrome and from those that developed preeclampsia and to assess the utility of PlGF as a screening tool for these conditions.

Methods

Residual second‐trimester maternal serum samples were retrieved from freezer storage for 39 cases of Down syndrome and 44 pregnancies that later developed preeclampsia. Each case was matched to 5 control samples for gestational age at collection and duration of freezer storage. PlGF levels were measured in each sample by enzyme‐linked immunosorbent assay (ELISA).

Results

PlGF levels increased with gestational age between 15 and 20 gestational weeks. After adjusting for gestational‐age effects, the median level of PlGF was 1.01 MoM in Down syndrome pregnancy and 0.74 MoM in pregnancies that developed preeclampsia, which were not significantly different from matched controls. The duration between sampling and onset of preeclampsia did not have an effect on the PlGF level.

Conclusion

PlGF levels are not significantly altered in second‐trimester maternal serum samples from cases of Down syndrome or in pregnancies that develop preeclampsia. Copyright © 2004 John Wiley & Sons, Ltd.
Temporary networks in polymer‐modified asphalts
Authors: Polacco Giovanni , Stastna Jiri , Vlachovicova Zora , Biondi Dario , Zanzotto Ludovit
Published: November 2004

The viscosity functions of several polymer‐modified asphalts (PMAs) were studied at different temperatures in steady‐state rate sweep tests. The materials were obtained by mixing different base asphalts with either styrene‐butadiene‐styrene (SBS), ethylene‐vinylacetate (EVA) or reactive ethylene terpolymers (RET). The first two polymers form a physical network that is swollen by the asphalt, while the latter is functionalized with glycidylmethacrylate (GMA) and can crosslink and/or chemically bond with the molecules of asphaltenes. In the presence of SBS or EVA, at certain temperatures, the viscosity curves exhibit a Newtonian behavior at low shear rates, followed by two distinct shear‐thinning phenomena. In some cases, the first shear‐thinning is preceded by a small shear‐thickening region. Similar phenomena are not present in the viscosity curves of the RET‐modified asphalts and can be related to a temporary nature of the physical polymer network. Polym. Eng. Sci. 44:2185–2193, 2004. © 2004 Society of Plastics Engineers.
Investigation of solids transport in a single‐screw extruder using a 3‐D discrete particle simulation
Authors: Moysey P. A. , Thompson M. R.
Published: November 2004

A non‐isothermal, 3‐D discrete particle simulation based on the discrete element method (DEM) was developed to simulate the solids‐conveying zone and feed hopper of a single‐screw extruder. The method considers each particle in a granular assembly as a separate entity that can interact with other particles or boundaries through collisions or lasting contacts. By using DEM to model the extrusion environment, a priori knowledge of the solids flow was not required in order to simulate the motion of a granular assembly with reasonable accuracy, allowing studies to be conducted in the absence of the solid plug assumption typical of classical solids‐conveying models. In this paper, predicted results were limited to low levels of compaction in the solids assembly (i.e., no particle deformation), in order to understand the behavior of the polymer pellets in their most dynamic state. The results of the DEM model showed reasonably good agreement with experimental data, providing comparable bulk values like output rate, yet also demonstrating its ability to capture the dynamics of solids particle conveying. The model captured the inherent variability of extrusion such as the low‐amplitude, high‐frequency fluctuations referred to as “solids pulsing” and the recirculation of pellets in the feed throat. Polym. Eng. Sci. 44:2203–2215, 2004. © 2004 Society of Plastics Engineers.
Fast screening method for the analysis of total flavonoid content in plants and foodstuffs by high‐performance liquid chromatography/electrospray ionization time‐of‐flight mass spectrometry with polarity switching
Authors: Tolonen Ari , Uusitalo Jouko
Published: November 2004

A liquid chromatography/electrospray ionization mass spectrometry (LC/ESI‐MS) method based on time‐of‐flight (TOF) MS with polarity switching and continuous exact mass measurement using a LockSpray ion source was developed for fast evaluation of the total flavonoid content in plants and foodstuffs. No complicated sample preparation was needed, but only a dilution of the extracts. A fast generic gradient elution and wide mass range acquisition was used with good sensitivity. The total analysis time was only 23 min. The ion chromatograms for flavonoid compounds were automatically extracted, and the fragmentation patterns obtained using positive ion mode and exact mass data for both polarities were used for the tentative identification of compounds. Software‐based automated searching of molecular ions for flavonoids and their glycosides (xylosides/arabinosides, rhamnosides, glucosides/galactosides) from total ion chromatograms was used. The compounds were quantified using quercetin, quercitrin, rutin and kuromanine as external standards and dextromethorphan as an internal standard. The detection limits ranged from 0.01–0.04 μg/mL, while the quantitation ranges obtained were 0.2–10 μg/mL for anthocyanins and 0.2–4 μg/mL for the other flavonoids. The accuracies within these ranges varied between 80–120% and precision was in the range 0–14% (relative standard deviation). Flavonoid contents of two medicinal plants (Hypericum perforatum and Rhodiola rosea), two grape red wines, two orange juices and two green teas were evaluated using the method, and the results obtained were in good agreement with those published previously. Copyright © 2004 John Wiley & Sons, Ltd.
Ein Glashaus für die Therme in Badenweiler
Authors: Schober Hans , Gerber Hannes , Schneider Jens
Published: November 2004

Im Kurort Badenweiler wurde im Zuge der Modernisierung der Thermenanlagen eine Verbindung zwischen zwei bestehenden Bauten mit einer Ganzglaskonstruktion geschaffen. Dieser Aufsatz berichtet von Entwurf, Konstruktion und Bemessung des Glashauses sowie dem verwendeten Sicherheitskonzept.
Analytische Berechnung der Eigenfrequenzen von Stäben mit konstantem Querschnitt und konstanter Massenbelegung
Authors: Rubin Helmut
Published: November 2004

Abgesehen von einfachen Stäben mit Lagerung nur an den Endpunkten werden zur Berechnung von Eigenfrequenzen meist Näherungsverfahren (z. B. Rayleigh‐Quotient mit Ansatzfunktionen für Biegelinie) angewendet. Dabei ist die Genauigkeit i. d. R. unbekannt und bei höheren Eigenwerten oft nicht mehr ausreichend. Im vorliegenden Beitrag wird eine genaue Berechnung beliebiger Eigenfrequenzen mit Hilfe der Übertragungsbeziehung gezeigt. Dabei handelt es sich um Querschwingungen von Stäben, die auch im Feld gelagert sein können oder dort Gelenke aufweisen. Für den Balken auf zwei Stützen mit Kragarmen (auch unterschiedlich lang) werden zur Ermittlung der ersten beiden Eigenfrequenzen Diagramme zur Verfügung gestellt.
Posttraumatic stress disorder following diagnosis of multiple sclerosis
Authors: Chalfant Anne Marie , Bryant Richard A. , Fulcher Gary
Published: November 2004

The Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM‐IV) recognizes lifethreatening illness as a potential stressor that can precipitate posttraumatic stress disorder (PTSD). This study represents the first study of PTSD in the context of having a diagnosis of multiple sclerosis (MS). Fifty‐eight MS patients were administered the Clinician Administered PTSD Scale, the Geriatric Depression Scale, and Disease Steps Questionnaire. Nine participants (16%) met symptom criteria for PTSD. In terms of those who satisfied the reexperiencing criterion, 75% of participants reported intrusions related to future‐oriented concerns about their prognosis. These findings suggest that a significant proportion of MS patients experience PTSD‐type reactions. These results are discussed in terms of the suitability of the PTSD framework to account for the distinctive nature of stress reactions secondary to life‐threatening illness.
CBT for Vietnamese refugees with treatment‐resistant PTSD and panic attacks: A pilot study
Authors: Hinton Devon E. , Pham Thang , Tran Minh , Safren Steven A. , Otto Michael W. , Pollack Mark H.
Published: November 2004

We examined the feasibility, acceptability, and therapeutic efficacy of a culturally adapted cognitive–behavior therapy (CBT) for twelve Vietnamese refugees with treatment‐resistant posttraumatic stress disorder (PTSD) and panic attacks. These patients were treated in two separate cohorts of six with staggered onset of treatment. Repeated measures Group × Time ANOVAs and between‐group comparisons indicated significant improvements, with large effect sizes (Cohen's d) for all outcome measures: Harvard Trauma Questionnaire (HTQ; d = 2.5); Anxiety Sensitivity Index (ASI: d = 4.3); Hopkins Symptom Checklist‐25 (HSCL‐25), anxiety subscale (d = 2.2); and Hopkins Symptom Checklist‐25, depression subscale (d = 2.0) scores. Likewise, the severity of (culturally related) headache‐and orthostasis‐cued panic attacks improved significantly across treatment.
Emotional disclosure in homeless people: A pilot study
Authors: de Vicente Aída , Muñoz Manuel , Pérez‐Santos Eloísa , Santos‐Olmo Ana Belén
Published: November 2004

Symptoms of stress are prevalent among the homeless. Growing evidence suggests that disclosure of traumatic experiences is beneficial to health. This pilot study examined the effects of an emotional disclosure protocol on a group of 8 homeless people, using a single‐group design. Clinical effectiveness was evaluated using the Impact of Event Scale, the Beck Depression Inventor, the Beck Anxiety Inventory, the Perceived Stress Scale, the Reading Span Task, and the Digit Span Test. Participant satisfaction was also measured. Results showed significant improvements in functioning at 1‐ and 6‐week follow‐up, and good satisfaction levels. The discussion remarks on the limitations (lack of a control group, small sample size, and other biases) and the need for more research in this topic.
Observation of very large and steep internal waves of elevation near the Massachusetts coast
Authors: Scotti Alberto , Pineda Jesús
Published: November 2004

We report on near‐bottom waves of elevation with amplitude nearly half the 25 m water column, very steep, and propagating into a sheared turbulent wave‐guide. The waves contained trapped cores transporting parcels of water shoreward. These large waves depart strongly from weakly‐nonlinear and weakly‐nonhydrostatic conditions and challenge established paradigms. They can also represent an important factor in the across‐shore transport of plankton and contaminants.
Role of hydrogen sulphide in haemorrhagic shock in the rat: protective effect of inhibitors of hydrogen sulphide biosynthesis
Authors: Mok Ying‐Yuan Pamela , Mohammed Atan Mohammed Shirhan Bin , Ping Cheong Yoke , Jing Wang Zhong , Bhatia Madhav , Moochhala Shabbir , Moore Philip K
Published: November 2004

Haemorrhagic shock (60 min) in the anaesthetized rat resulted in a prolonged fall in the mean arterial blood pressure (MAP) and heart rate (HR).

Pre‐treatment (30 min before shock) or post‐treatment (60 min after shock) with inhibitors of cystathionine γ lyase (CSE; converts cysteine into hydrogen sulphide (H2S)), dl‐propargylglycine or β‐cyanoalanine (50 mg kg−1, i.v.), or glibenclamide (40 mg kg−1, i.p.), produced a rapid, partial restoration in MAP and HR. Neither saline nor DMSO affected MAP or HR.

Plasma H2S concentration was elevated 60 min after blood withdrawal (37.5±1.3 μm, n=18 c.f. 28.9±1.4 μm, n=15, P<0.05).

The conversion of cysteine to H2S by liver (but not kidney) homogenates prepared from animals killed 60 min after withdrawal of blood was significantly increased (52.1±1.6 c.f. 39.8±4.1 nmol mg protein−1, n=8, P<0.05), as was liver CSE mRNA (2.7 ×). Both PAG (IC50, 55.0±3.2 μm) and BCA (IC50, 6.5±1.2 μm) inhibited liver H2S synthesizing activity in vitro.

Pre‐treatment of animals with PAG or BCA (50 mg kg−1, i.p.) but not glibenclamide (40 mg kg−1, i.p., KATP channel inhibitor) abolished the rise in plasma H2S in animals exposed to 60 min haemorrhagic shock and prevented the augmented biosynthesis of H2S from cysteine in liver.

These results demonstrate that H2S plays a role in haemorrhagic shock in the rat. CSE inhibitors may provide a novel approach to the treatment of haemorrhagic shock.

British Journal of Pharmacology (2004) 143, 881–889. doi:10.1038/sj.bjp.0706014