bluuebunny/crossref_metadata_2025 huggingface dataset:
EGFR protein overexpression and gene amplification in squamous cell carcinomas of the esophagus
Authors: Hanawa Mitsuhiko , Suzuki Shioto , Dobashi Yoh , Yamane Tetsu , Kono Koji , Enomoto Nobuyuki , Ooi Akishi
Published: December 2005

Overexpression of epidermal growth factor receptor (EGFR) is observed in many cancers, sometimes accompanied by gene amplification. Recently, several clinical therapies targeting EGFR were developed, but the eligibility criteria for these therapies is not fully established. To develop such eligibility criteria for esophageal squamous cell carcinoma (ESCC), we sought to clarify: (i) the exact frequency of EGFR overexpression, (ii) the relationship between protein overexpression and gene amplification, (iii) the relationship between gene amplification and specific gene mutations and (iv) the correlation between the status of EGFR and clinical or pathological features. Immunohistochemistry revealed that EGFR protein is overexpressed in 53 (50%) of the 106 ESCC examined. Fluorescence in situ hybridization (FISH) indicated clear EGFR gene amplification in 15 of the 53 tumors, somewhat higher EGFR copy in 32 cases, and no increase in 6 cases. Gene amplification was significantly associated with high level overexpression. Direct sequencing of exons 19 and 21 of EGFR revealed no mutations in 15 tumors exhibiting gene amplification, and no mutations in 25 tumors not exhibiting gene amplification. Overexpression of EGFR was significantly correlated with depth of invasion of the tumor.In conclusion, anti‐EGFR therapies may be appropriate for patients with ESCC. We assume that combined analyses by immunohistochemistry/FISH would clarify aberrations in protein and gene function, and could help to identify those patients who may benefit from anti‐EGFR therapy. © 2005 Wiley‐Liss, Inc.
Premenopausal levels of circulating insulin‐like growth factor I and the risk of postmenopausal breast cancer
Authors: Rollison Dana E. , Newschaffer Craig J. , Tao Yuzhen , Pollak Michael , Helzlsouer Kathy J.
Published: December 2005

Increased levels of insulin‐like growth factor I (IGF‐I) may directly stimulate breast cell proliferation and promote growth and survival of transformed cells. Higher levels of IGF‐I have been associated with increased risk of premenopausal breast cancer but not postmenopausal breast cancer. We investigated whether circulating levels of IGF‐I prior to menopause are associated with breast cancer diagnosed after menopause in a population‐based nested case‐control study. Female cohort participants were enrolled in 1974 (n = 15,192) and 1989 (n = 18,724) and blood was drawn. Cases were women diagnosed with primary breast cancer at ages ≥50, of whom 152 were premenopausal at blood draw. One control was matched to each case on cohort participation, age, ethnic group, menopausal status and date of blood draw. Levels of IGF‐I and IGF binding protein 3 (IGFBP‐3) were measured using enzyme‐linked immunoabsorbant assays assays. The association between IGF‐I and breast cancer was determined using conditional logistic regression, adjusting for IGFBP‐3. IGF‐I levels decreased with age (p = 0.0001). Prior to age‐stratification, IGF‐I levels neither measured before nor after menopause were associated with postmenopausal breast cancer. After age‐stratification, associations were suggested in the youngest premenopausal age group (upper vs. lowest third: odds ratio (OR) = 5.31, 95% confidence intervals (CI) = 0.85–33.13; p trend = 0.06) and oldest postmenopausal age group (upper vs. lowest third: OR = 3.41, 95% CI = 0.66–17.71; p trend = 0.13). The association between circulating levels of IGF‐I and postmenopausal breast cancer risk may be modified by age. Increased levels of circulating IGF‐I may be of particular interest in the younger premenopausal women and older postmenopausal women. Age‐stratification should be undertaken in larger investigations of IGF‐I levels as predictors of postmenopausal breast cancer. © 2005 Wiley‐Liss, Inc.
Change in the Arctic influence on Bering Sea climate during the twentieth century
Authors: Wang Muyin , Overland James E. , Percival Donald B. , Mofjeld Harold O.
Published: December 2005

Surface air temperatures (SAT) from three Alaskan weather stations in a north–south section (Barrow, Nome, and St. Paul) show that on a decadal scale, the correlation among the stations changed during the past century. Before the 1960s, Barrow and Nome were dominated by Arctic air masses and St. Paul was dominated by North Pacific maritime air masses. After the 1960s, the SAT correlation in winter between Barrow and St. Paul increased from 0.2 to 0.7 and between Nome and St. Paul from 0.4 to 0.8, implying greater north–south penetration of both air masses. The correlation change in the winter of the Barrow–St. Paul pair is significant at a 95% confidence level. The Nome–St. Paul pair in spring also shows some of this characteristic change in correlation. Relatively stable, high correlations are found among the stations in the fall; correlations are low in the summer. Our study shows a change in the climatological structure of the Bering Sea in the late twentieth century, at present of unknown origin and occurring earlier than the well‐known 1976/1977 shift. These climatological results further support the concept that the southeast Bering Sea ecosystem may have been dominated by Arctic species for most of the century, with a gradual replacement by sub‐Arctic species in the last 30 years. Copyright © 2005 Royal Meteorological Society.
Unstable ENSO Relationship with Indian regional rainfall
Authors: Kane R. P.
Published: December 2005

In earlier years, El Niños had a strong association with droughts in India. However, in recent years, this relationship seems to have weakened, and even the strong event of 1997–1998 did not produce the expected effects. In the 133‐year data, only about 60% of the El Niño and La Niña are effective, and the magnitudes of the anomalies are not in good correlations with the strength of the ENSO. This weakening of ENSO effects in recent years is known to meteorologists. The Indian Meteorological Department (IMD) scientists have formulated prediction schemes, but these are not fully satisfactory. The public and the press are still swayed only by possible El Niño effects, as happened in 2005 when Pacific warming occurred in February. The meteorologists had to assure the press that this was a case of an ‘aborted El Niño’, with quiet conditions expected to return by the end of 2005. Considering the experience of the 1997–1998 El Niño, when a strong El Niño developed suddenly, a prediction of a quiet 2005 can be hazardous. More importantly, even if an El Niño develops in the next few months, the press should be told that the chance of strong El Niño effects (droughts) is only about 60%, and these too may be very different in different regions of India. Copyright © 2005 Royal Meteorological Society.
Porcine skin ED50 damage thresholds for 2,000 nm laser irradiation
Authors: Chen Bo , O'Dell Daniel C. , Thomsen Sharon L. , Rockwell Benjamin A. , Welch Ashley J.
Published: December 2005

Background and Objectives

To gain refinement in safe‐exposure limits, indicated by the maximum permissible exposure (MPE) limits, the minimum visible lesion thresholds for three spot sizes (5–15 mm) and four exposure durations (0.25–2.5 seconds) were determined for the skin at 2,000 nm continuous wave laser irradiation.

Study Design/Materials and Methods

A series of experiments were conducted in vivo on female Yucatan mini‐pigs to determine the ED50 damage thresholds for 2,000 nm continuous wave laser irradiation. The study employed Gaussian laser beam exposures with spot diameters (1/e2) of 4.83, 9.65, and 14.65 mm and exposure durations of 0.25, 0.5, 1.0, and 2.5 seconds as a function of laser power. The effect of each irradiation was evaluated within 1 minute after irradiation and the final determination was made at 48 hours post‐exposure. Probit analysis was conducted to estimate the dose for 50% probability of laser‐induced damage (ED50), defined as persistent redness at the site of irradiation for the mini‐pig skin after 48 hours.

Results

The MPE spot size and exposure duration trends for 2,000 nm laser exposure is consistent for exposure diameters less than 3.5 mm. However, for larger exposure diameters of 4.83, 9.65, and 14.65 mm and exposure duration longer than 0.25 second, the current MPEs are bigger than one tenth of our damage thresholds. For Gaussian laser profile, which is common for many laser output irradiance distributions, lower energy is required to generate a lesion on skin for smaller spot sizes and shorter exposure duration. On the other hand, for spot sizes greater than 4.83 mm and exposure duration over 0.25 second, the average radiant exposure at threshold is inversely proportional to spot size. The irradiance‐time and temperature‐time power law at the threshold were investigated as well and showed that the irradiance‐time power law was a close approximation to estimate laser irradiance at ED50 damage threshold.

Conclusions

The thresholds study shows that consideration for lowering the MPE standards should be explored as the laser beam diameter becomes larger than 3.5 mm. Based on the limited experimental data, the duration and size dependences of the ED50 damage thresholds could be described by an empirical equation: Irradiance at the threshold = (5.669−1.81×spot diameter)×exposure duration−0.794. Lasers Surg. Med. 37:373–381, 2005. © 2005 Wiley‐Liss, Inc.
Unusual Effect of Diethyl Zinc and Triisobutylaluminium in Ethylene/1‐Hexene Copolymerisation using an MgCl2‐Supported Ziegler‐Natta Catalyst
Authors: Périn Soazig G. M. , Severn John R. , Koning Cor E. , Chadwick John C.
Published: December 2005

Summary: The use of triisobutylaluminium and diethyl zinc as cocatalyst and chain transfer agent respectively in ethylene/1‐hexene copolymerisation, carried out with a Ziegler‐Natta catalyst of type MgCl2/TiCl4/diisobutyl phthalate, has been found to give significantly higher comonomer incorporation than was obtained when triethylaluminium was used in combination with diethyl zinc. Triisobutylaluminium reacts readily with diethyl zinc, yielding metallic zinc, most likely via the formation of intermediate hydride species. In contrast, the use of 2,6‐dimethylpyridine as external donor in this system has been found to have relatively little effect on comonomer incorporation and distribution, indicating that a change from tendentially isospecific to syndiospecific propagation in propene polymerisation is not accompanied by a major improvement in comonomer distribution in ethylene/1‐hexene copolymerisation.

1H NMR spectrum of the liquid product of the reaction between triisobutylaluminium and diethyl zinc.

image

1H NMR spectrum of the liquid product of the reaction between triisobutylaluminium and diethyl zinc.
Hydropower scheduling and financial risk management
Authors: Kristiansen Tarjei
Published: December 2005

This paper describes a risk management tool for hydropower generators and its application to Norway's second‐largest generation company and largest electricity consumer, Norsk Hydro ASA. The tool considers both operations scheduling and the utilization of financial contracts for risk management. Financial risks are accounted for by penalizing incomes below a reference income. The risk management problem is solved by a combination of stochastic dual dynamic programming and stochastic dynamic programming. Simulations demonstrate that lower income scenarios improve when risk aversion is introduced. Copyright © 2005 John Wiley & Sons, Ltd.
Antiplane incremental states in fiber reinforced elastic composites and in piezoelectric crystals
Authors: Cracium Eduard‐Marius
Published: December 2005

The behavior of the incremental displacements on the faces and on the line ahead and behind of an antiplane crack contained in a prestressed fiber reinforced elastic composite and in a prestressed and prepolarized piezoelectric crystal is studied in the paper. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anisotropic damage for higher order continuum models
Authors: Ebinger Tobias , Steeb Holger , Diebels Stefan
Published: December 2005

A continuum model for the description of the deformation behavior of foam‐like structures with open cells is presented. On the microlevel the struts can be modeled by beam elements. The macroscopic model, which is derived by homogenization of microscopic quantities, is extended towards anisotropic damage. Thereby, it is considered that not only the normal and shear forces transduced by the microstructural beam elements cause damage but also the bending moments. Thus, on the macroscale a standard continuum theory in conjunction with first order homogenization is not sufficient because the effects of the bending moments would be neglected. An extended continuum theory is chosen on the macroscale considering the bending moments on the microscale requiring a second order homogenization procedure. The idea of including microstructural information by homogenization without formulation of macroscopic constitutive and evolution equations is known from literature as FE2 model. The capability of the presented model is demonstrated in a numerical example. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Deformation Driven Homogenization of Fracturing Solids
Authors: Gürses Ercan , Birkle Manuel , Miehe Christian
Published: December 2005

The paper discusses numerical formulations of the homogenization for solids with discrete crack development. We focus on multi–phase microstructures of heterogeneous materials, where fracture occurs in the form of debonding mechanisms as well as matrix cracking. The definition of overall properties critically depends on the developing discontinuities. To this end, we extend continuous formulations [1] to microstructures with discontinuities [2]. The basic underlying structure is a canonical variational formulation in the fully nonlinear range based on incremental energy minimization. We develop algorithms for numerical homogenization of fracturing solids in a deformation–driven context with non–trivial formulations of boundary conditions for (i) linear deformation and (ii) uniform tractions. The overall response of composite materials with fracturing microstructures are investigated. As a key result, we show the significance of the proposed non–trivial formulation of a traction–type boundary condition in the deformation–driven context. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Formulation of the material force approach for elastic and inelastic materials
Authors: Näser Bastian , Kaliske Michael , André Markus
Published: December 2005

Fracture mechanical investigations are important for the durability of fracture sensitive products. Fracture mechanical simulations help to shorten the product development cycle and to decrease product costs. The so‐called material force approach as an efficient tool is used to determine fracture mechanical parameters for elastic and inelastic materials. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the macroscopic material behaviour of textile reinforced concrete undertensile loading
Authors: Richter Mike
Published: December 2005

This paper concerns with the development of the macroscopic material behaviour of textile reinforced concrete (TRC) using an analytical approach. Therefore the heterogeneous structure of TRC is modelled on the mesoscopic level. The overall material behaviour on the macroscopic level is obtained by means of the homogenisation technique. The analytical approach is based on the micro mechanical solution for a single inclusion according to Eshelby. In extension of this solution for multidirectional reinforced concrete an effective field approximation is used. This approach considers the interactions between the different orientated rovings and the micro cracks in an average sense. For the mechanical modelling of the bond behaviour between roving and matrix after initiating of the macro cracking a slip based bond model with a multiple linear shear stress‐slip relation is used. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Direct FEM Simulation and Replacement Crack Approach for Mixed Mode Crack Growth in a Unit Cell
Authors: Sch?tte Henning , Molla‐Abbasi Kianoush
Published: December 2005

A whole class of continuum damage models uses microcracks as the main source of reduction of stiffness. For the growth of these cracks mostly only mode I is considered. We want to present a method to describe mixed mode crack growth inside a unit cell with a crack, without the need of a direct FEM simulation of crack growth per integration point. We replace the infinitesimal grown and kinked crack with the help of a replacement crack model. This replacement method is mainly based on the equivalence of the dissipation of the original kinking and the replacement crack. The resulting evolution of the stiffness of the unit cell is compared to a direct FEM simulation of mixed mode crack growth. The crack growth criterion used is the principle of maximum energy release rate, which has shown to be a direct consequence of a variational principle of a body with a crack [1]. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A consistent theory for poroelastic plates
Authors: Busse Anke , Schanz Martin
Published: December 2005

In many fields of engineering thin porous components are used, e.g. as damping elements for noise insulation in cars or walls in buildings. Today these elements are often calculated using a numerical 3‐D model. Because of numerical problems which occur using a 3‐D model for thin transversly loaded structures a plate theory is advantageous. To take into account the porous structure as well as the damping effect of the porosity of these components a poroelastic plate theory is necessary.

Several posibilities exist to establish plate theories. Generally, methods to derive a plate theory require a priory assumptions motivated by engineering intuition (like the classical Kirchhoff normal hypothesis).

In this contribution a priori assumptions are not used. Plate theories of different orders are derived from the 3‐D poroelastic theory using series expansion. For elastic plates this idea was introduced in [3]. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Finite Element Formulation for the Nonlinear Analysis of Piezoelectric Three‐Dimensional Beam Structures
Authors: Butz Alexander , Klinkel Sven
Published: December 2005

A finite element formulation for a three‐dimensional piezoelectric beam which includes geometrical and material nonlinearities is presented. To account for the piezoelectric effect, the coupling between the mechanical stress and the electrical displacement is considered. Based on the Timoshenko theory, an eccentric beam formulation is introduced which provides an efficient model to analyze piezoelectric structures. The geometrically nonlinear assumption allows the calculation of large deformations including buckling analysis. A quadratic approximation of the electric potential through the cross section of the beam ensures the fulfilment of the charge conservation law exactly. This assumption leads to a finite element formulation with six mechanical and five electrical degrees of freedom per node. To take into account the typical ferroelectric hysteresis phenomena, a nonlinear material model is essential. For this purpose, the phenomenological Preisach model is implemented into the beam formulation which provides an efficient determination of the remanent part of the polarization. The applicability of the introduced beam formulation is discussed with respect to available data from literature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Second order homogenization method based on higher order finite elements
Authors: D?ster A. , Rank E. , Diebels S. , Ebinger T. , Steeb H.
Published: December 2005

Modeling materials with lattice‐like microstructures like open‐cell foams requires an extended continuum mechanical setting on the macroscopic scale, e. g. a micropolar or micromorphic theory. In order to avoid the formulation of constitutive equations a higher order numerical homogenization scheme (FE2) is proposed. Therefore, each integration point possesses its own microstructure which, in the present case, consists of beam‐like elements representing the cell walls. In this paper, the microstructures are discretized by continuum‐based higher order locking free finite elements with high aspect ratios, leading to a numerically efficient treatment of a local displacement‐driven boundary value problem according to the macroscopic strain and curvature. The resulting stress distributions in the microstructures are homogenized to macroscopic stresses and couple stresses. The approach is demonstrated by a numerical example. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerische Aufbereitung der Stoffgesetze spezieller thermoplastischer Festigkeitsträger zur Berechnung von Elastomer‐Faserverbunde
Authors: Jacob H.‐G. , Besdo D. , Oehmen K. H.
Published: December 2005

Im Bereich der gummiartigen Werkstoffe wird derzeitig sehr emsig geforscht. Hier werden Arbeiten vorgestellt, die phänomenologisch und physikalisch basiert sind. Mit den entwickelten Materialgesetzen, lassen sich die wesentlichen physikalischen Eigenschaften des Elastomers schon in befriedigendem Maße wiedergeben. Um jedoch Berechnungen an einem Gummi‐Faser‐Verbundsystem durchführen zu können, benötigt man noch eine Materialbeschreibung des Festigkeitsträgers. Ein thermoplastischer Festigkeitsträger verhält sich, ebenso wie Gummimaterial, stark nichtlinear, erleidet große Deformationen und zeigt deutliche Hystereseerscheinungen während eines Belastungszyklus. Dieses Verhalten muss in einem das Fadenmaterial beschreibenden Stoffgesetz ebenso enthalten sein, wie der strukturelle Aufbau des Fadens in den Deformationsmaßen. Die Berücksichtigung des Aufbaus des Festigkeitsträgers macht es erst möglich, dass wesentliche physikalische Effekte im Verbund berechnet und dann visualisiert werden können. Die Berechnung von Luftfedern und Fahrzeugreifen ist unter diesen Umständen sehr schwierig. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A model‐adaptive coupling strategy of non‐linear and model‐reduced linear subsystems
Authors: Rickelt Christian , Reese Stefanie
Published: December 2005

This article introduces a new three‐level discretisation strategy in which the entire structure is divided into subsystems according to the required modelling accuracy(continuum, structural and substituted model level). This note especially focuses on the transition between the structural and the substituted model level. The principle idea is to separate the structure strictly into linear and non‐linear substructures by the concept of coupling forces. Additionally the linear parts are reduced by modal reduction. The method is verified by a transient analysis of a bridge arch having regard to the evolution of damage. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interlaminar Stresses at Corners of Laminate Reinforcements
Authors: Wigger Hubertus Michael , Becker Wilfried
Published: December 2005

For inplane loaded plates the use of two laminate patches which are attached symmetrically to a base laminate with respect to the out‐of‐plane direction is a possibility to reinforce a highly stressed region. But corners at the patches' boundaries constitute a source for stress localizations. The expedient knowledge of the local mechanical inplane fields at such corners can be obtained with the boundary finite element method (BFEM). In order to investigate the intrinsically three‐dimensional nature of the laminate corner setup the gradients of the inplane fields are readily evaluated since they are provided by the BFEM in a semi‐analytical way. The interlaminar stresses inside the plate are retrieved by equilibrium considerations on a ply‐by‐ply basis. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solving plasticity problems by a perturbation technique
Authors: Zahrouni H. , Braikat B. , Damil N. , Potier‐Ferry M.
Published: December 2005

The present work deals with a new technique to regularize the elastoplastic constitutive laws in the framework of the asymptotic numerical method. In this contribution, we limit ourselves to uniaxial stress train relation but the procedure is implemented also in a finite element code for plain stress case and for different work hardening laws. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Incompressible Flows with Coupled FEM/EFG shape functions
Authors: Fries Thomas‐Peter , Matthies Hermann G.
Published: December 2005

A method for the simulation of incompressible flows is described which is able to handle geometrically complex situations, such as those including moving and rotating objects in the flow field. In these situations, standard meshbased methods such as the finite element method (FEM) may fail if a suitable mesh can not be maintained at reasonable cost throughout the simulation. The proposed method introduces the desirable features of meshfree methods in parts of the domain where the mesh generates problems. This is realized by coupling FEM and element‐free Galerkin (EFG) shape functions. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Towards High Order Numerical Simulation of Aeolian Tones
Authors: Müller Bernhard
Published: December 2005

Strictly stable high order finite difference operators have been applied to the compressible Navier‐Stokes equations in perturbation form for low Mach number computational aeroacoustics. Aeolian tones generated by vortex shedding from a circular cylinder have been simulated. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerische Berechnungen der Bewegungsvorgänge während des Gärungsprozesses in einem Modell eines zylindrokonischen Gärtanks
Authors: Szymczyk J. A. , Meironke H. , Nurzynski M.
Published: December 2005

Die Kenntnis der Konvektionsvorgänge in den heute fast ausschließlich verwendeten zylindrokonischen Gär‐ und Lagertanks stellt eine notwendige Voraussetzung dar, wenn man den Prozess der Bierherstellung, insbesondere der Gärung, optimieren will. Im Rahmen der Untersuchungen der konvektiven Transportvorgänge in Gär‐ und Lagertanks werden in der folgenden Arbeit die Ergebnisse der numerischen Simulation der Strömungsvorgänge auf Basis eines Finite‐Volumen‐Verfahrens präsentiert. Grundlage der Berechnungen stellt ein spezieller Gär‐ und Lagertank (270 Liter) dar, der den realen Gärungs‐ und Lagerungsprozess realisieren kann und in einer weiteren Betriebsart in der Lage ist, eine simulierte experimentelle Gärung mittels definierter Steuerung von Heizungs‐ und Kühlungsrandbedingungen durchzuführen. Ein wesentlicher Schwerpunkt dieser Arbeit ist die Erstellung eines Modells, das dem realen Strömungsverhalten, in der experimentell simulierten Gärung in dem 270 Liter Tank, nahezu entspricht. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Applications of Wavelet Packets in System Identification
Authors: Brehm Maik , Zabel Volkmar , Markwardt Klaus
Published: December 2005

As existing facilities / structures are modi.ed, as engineering knowledge advances and as the requirements to extend life increase, industries must demonstrate that operations can continue safely and economically. This is one objective of the Thematic Network SAFERELNET [1], where reassessment strategies are covered. One possibility to enhance the knowledge is an experimental assessment. This study aims to identify system parameters like mass, damping and stiffness of a dynamical system using wavelet packets. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of material parameters in extended contiuum mechanicalmodels
Authors: Chatzouridou Anthippi , Diebels Stefan
Published: December 2005

A method for the identification of material parameters of constitutive models describing foamed materials is discussed in the present work. One can model foamed materials in two ways: using a lattice‐like micro‐model or alternatively a continuum mechanical approach. A beam model is used for the description of foams on a microscopic scale and alternatively an extended continuum model based on the Cosserat theory is employed on the macroscopic scale. By performing numerical shear tests at specimens of different sizes, we can observe the following effect on both models: The distribution of the rotations shows a strong boundary layer character at the top and bottom boundary of the specimen, whereas at the inner part it takes a constant value. These boundary layer effects do not scale with the size of the specimen, as a result specimens occur to be stiffer, see [1]. The goal is to perform a fitting of the Cosserat parameters by comparing the results of the macroscopic model to these of the microscopic one. The parameter fitting concerns an inverse problem which is treated within the framework of stochastic optimization methods. An evolutionary algorithm is used in combination with a response surface method for the identification of the material parameters. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Design and Control of a Pneumatic Hybrid Actuator
Authors: Dhanu Singh M. , Liem K. , Kecskeméthy A. , Neumann R.
Published: December 2005

To simulate arbitrary force/displacement relationships, a hybrid actuator consisting of a .uidic muscle and a linear pressure spring is presented. Fluidic Muscles are interesting in their use as actuators in robotics, since they have a high power/weight ratio, a slip‐stick free motion and a long durability. The operating point is de.ned as the half contracted‐stroke of the muscle. The present paper describes a procedure to simulate virtual stiffness of a linear actuator by choosing an operating point of the pre‐stressed muscle and applying PID Control to produce desired forces as function of state. The results are presented for a testbed. It is shown how the aforementioned control scheme produces a rapid and .exible stiffnes simulation. The device can be employed for later use in general environments such as motion simulations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monitoring of the Nonlinear Dynamics of Railway Wheelsets
Authors: Glösmann Philipp , Kreuzer Edwin
Published: December 2005

This paper focuses on the identification of dominant coherent structures in the nonlinear dynamic behavior of railway wheelsets by Karhunen‐Loève‐Transform (KLT). The ultimate goal is the characterization of the rolling quality of railway wheelsets. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Konstitutive Charakterisierung von Kautschukmischungen mit dem Hochdruckkapillarviskosimeter
Authors: Müllner Herbert Wolfgang , Eberhardsteiner Josef , Wieczorek André
Published: December 2005

In diesem Beitrag wird über eine Parameteridentifikation für die Bestimmung der viskosen Eigenschaften von Kautschukmischungen berichtet. Bisher wurde die Kopplung der Zustandsgrößen durch die Anwendung von Korrekturverfahren berücksichtigt. Mit Hilfe eines Iterationsverfahrens werden die Materialparameter nun direkt ermittelt. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Shear Modulus Identification in Soft Tissue‐like Materials
Authors: Reichling Stefan , Timme Bruhns Otto , Khaled Walaa , Ermert Helmut
Published: December 2005

Elastography is a method motivated by the observation that changes in tissue elasticity are generally correlated with pathological phenomena. By applying quasi‐static compression to the considered tissue‐like object, components of the internal displacement field can be determined with an ultrasound‐elastography system. Based on the assumption that the investigated material is elastic, isotropic, and nearly incompressible, the stiffness distribution can be calculated from the displacement field in the framework of inverse problems. In this paper, existing procedures for calculating the shear modulus distribution with knowledge of internal displacement field are presented. The methods are compared with respect to the stability of algorithms using numerical simulations and ultrasound measurements. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental Observations on Superelastic NiTi‐Shape Memory Alloys and Suggestions for Modelling
Authors: Schmidt Ina , Vishnevsky Andrey , Lammering Rolf
Published: December 2005

During stress‐induced transformation NiTi shows a distinct generation of transformation bands. A simple one‐dimensional model for superelastic NiTi wires has been developed to show exemplarily methods to account for these bands in plasticitybased models. To clarify the dependence of the transformation bands on the distribution of latent heat and therefore on the mechanical behaviour, optical and thermographical experiments have been performed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Boundary Conditions Modelling of the Fluid‐Structure Interaction at Wind Tunnel Testing
Authors: Rašuo Boško
Published: December 2005

The present paper discusses some newer developments, but concentrates mainly on the specification of the wall boundary conditions that are of importance for the calculation of the wind tunnel wall interference. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fully–coupled model for electrokinetic flow and transport in microchannels
Authors: Barz Dominik P. J. , Ehrhard Peter
Published: December 2005

We investigate the electrokinetic flow and mass transport in microchannels. Therefore, mathematical models of the electrical, fluid‐mechanical and chemical processes are established. Within the electrical double layer (EDL), approximative analytical solutions can be found and matched asymptotically to the numerical (FEM) solution of the channel core. The results of the simulations show a strong coupling between the processes. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Anisotropy Invariant Reynolds Stress Model and Its Application to Fully Developed Channel Flows
Authors: Breuer M. , Ray S. , Kumar V. , Jovanović J. , Durst F.
Published: December 2005

The paper is concerned with a second‐moment closure for the Reynolds‐averaged Navier‐Stokes equations which relies on the anisotropy invariant theory. It is shown how the anisotropy invariant map can be used to derive reasonable closure assumptions for turbulent flows. Furthermore, a first highly encouraging application for an inhomogeneous flow is discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Das instationäre Strömungsfeld hinter einer arteriellen Stenose
Authors: Chen Xueming , Böhme Gert
Published: December 2005

In der vorliegen Arbeit geht es darum, ein grundsätzliches Verständnis für die komplexe instationäre Durchströmung eines pathologischen Blutgefäßes zu entwickeln. Zur Analyse der Strömungsprozesse wird eine modellhafte Untersuchung mit Hilfe der Particle Image Velocimetry (PIV) durchgeführt. Ausgehend von der Reynoldsschen und der Strouhalschen Ähnlichkeit wurde ein Versuchsstand aufgebaut, der aus dem optisch zugänglichen Modell der arteriellen Stenose mit einer im Längsschnitt cosinusförmigen Einschnürung und einem System zur Realisierung der pulsierenden Blutströmung besteht. Mit dem PIV‐System wurde das Geschwindigkeitsfeld im Längsschnitt hinter der Stenose zu verschiedenen Zeitpunkten des Pulszyklus gemessen. Auf diese Weise werden die Strömungsvorgänge während der Beschleunigungsphase, der Verzögerungsphase und der Konstantphase experimentell charakterisiert. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerische Simulation der nicht‐isothermen Strömung in Einwellenextrudern
Authors: Conzen Carsten , Wünsch Olaf
Published: December 2005

Extruder werden hauptsächlich zum Aufschmelzen und Fördern von Kunststoffen verwendet. Die heie Kunststoffschmelze ist ein nicht‐newtonsches Fluid, dessen Viskosität von der Temperatur und der Schergeschwindigkeit anhängt. Die Strömung und das Temperaturfeld in der Schmelze werden analysiert und in Form von Kennlinien für Durchsatz und Leistung präsentiert. Ausserdem wird der Einfluss der kinematischen Randbedingungen auf das Temperaturfeld gezeigt. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Critical Velocities and Flow Rate Limitations in Open Capillary Channel Flows (CCF)
Authors: Haake Dennis , Rosendahl Uwe , Ohlhoff Antje , Dreyer Michael
Published: December 2005

In the present study a forced liquid flow through an open capillary channel is investigated experimentally and numerically under reduced gravity conditions (microgravity). An open capillary channel is a structure that establishes a liquid flow path at low Bond numbers, when the capillary pressure caused by the surface tension force dominates in comparison to the hydrostatic pressure induced by gravitational or residual accelerations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experiments on the flow stability in a double‐lid‐driven cavity
Authors: Siegmann‐Hegerfeld T. , Schmidt J.‐R. , Albensoeder S. , Kuhlmann H. C.
Published: December 2005

The stability of the two‐dimensional, steady, incompressible flow in a rectangular square cavity is investigated experimentally for the parallel motion of two facing walls. The critical Reynolds numbers for the onset of three‐dimensional steady flow, its structure, and the bifurcation diagram of the velocity field, measured by LDV, agree with numerical predictions. It is observed that the wavelength of the selected pattern increases with the Reynolds number. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Understanding the Robustness of Dynamic model in Large Eddy Simulation
Authors: Kumar Akula Rajani , Sadiki Amsini , Janicka Johannes
Published: December 2005

One of the main question faced by the large eddy simulation(LES) users is, why dynamic model works? Many authors have tried to answer this question with little sucess. In the present work we would like to show the insensitiveness of the dynamic model to the externaly introduced variation in the model coefficent, which proves the robustnessof the model. Analytical and physical reasoning for this behaviour is given by simulating the fully developed channel flow case. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wind Gusts and Small Scale Intermittency in Atmospheric Flows
Authors: Barth Stephan , Böttcher Frank , Peinke Joachim
Published: December 2005

We introduce a model that interprets atmospheric increment statistics as a large scale mixture of subsets of isotropic statistics. When mixing is weak the same statistics as for isotropic turbulence is recovered while for strong mixing robust intermittency is obtained. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
DNS and Experiment of a Turbulent Channel Flow with StreamwiseRotation ‐ Study of the Cross Flow Phenomena
Authors: Weller Tanja , Oberlack Martin , Recktenwald Ingo , Schröder Wolfgang
Published: December 2005

Modelling of rotating turbulent flows is a major issue in engineering applications. Intensive research has been dedicated to rotating channel flows in spanwise direction such as by [1], [2] to name only two. In this work a turbulent channel flow rotating about the streamwise direction is presented. The theory is based on the investigations of [4] employing the symmetry theory. It was found that a cross flow in the spanwise direction is induced. A series of direct numerical simulations (DNS) at different rotation numbers is carried out to examine these effects. Further, the results of the DNS are compared to the measuremets of a corresponding experiment. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bacterial gene therapy strategies
Authors: Vassaux Georges , Nitcheu Josianne , Jezzard Sarah , Lemoine Nick R
Published: December 2005

The ability of bacteria to mediate gene transfer has only recently been established and these observations have led to the utilization of various bacterial strains in gene therapy. The types of bacteria used include attenuated strains of Salmonella, Shigella, Listeria, and Yersinia, as well as non‐pathogenic Escherichia coli. For some of these vectors, the mechanism of DNA transfer from the bacteria to the mammalian cell is not yet fully understood but their potential to deliver therapeutic molecules has been demonstrated in vitro and in vivo in experimental models. Therapeutic benefits have been observed in vaccination against infectious diseases, immunotherapy against cancer, and topical delivery of immunomodulatory cytokines in inflammatory bowel disease. In the case of attenuated Salmonella, used as a tumour‐targeting vector, clinical trials in humans have demonstrated the proof of principle but they have also highlighted the need for the generation of strains with reduced toxicities and improved colonization properties. Altogether, the encouraging results obtained in the studies presented in this review justify further development of bacteria as a therapeutic vector against many types of pathology. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
HPV‐mediated cervical carcinogenesis: concepts and clinical implications
Authors: Snijders Peter JF , Steenbergen Renske DM , Heideman Daniëlle AM , Meijer Chris JLM
Published: December 2005

Persistent infection with a high‐risk human papillomavirus (hrHPV) is generally accepted as a necessary cause of cervical cancer. However, cervical cancer is a rare complication of an hrHPV infection since most such infections are transient, not even giving rise to cervical lesions. On average, it takes 12–15 years before a persistent hrHPV infection may ultimately, via consecutive premalignant stages (ie CIN lesions), lead to an overt cervical carcinoma. This argues that HPV‐induced cervical carcinogenesis is multi‐step in nature. In this review, the data from hrHPV‐mediated in vitro transformation studies and those obtained from analysis of clinical specimens have been merged into a cervical cancer progression model. According to this model, a crucial decision maker in the early stages following infection involves individual susceptibility for certain HPV types depending on the genetic make‐up of immune surveillance determinants. Once a CIN lesion has developed, altered transcriptional regulation of the viral E6/E7 oncogenes, resulting in genomic instability and distinguishing the process of cell transformation from a productive viral infection, probably provides the subsequent important step towards malignancy. The additional (epi)genetic alterations that subsequently accumulate in high‐grade CIN lesions may result in overt malignancy via immortality and growth conditions that gradually become less sensitive to growth‐modulating influences mediated by cytokines and cell–cell and cell–matrix adhesions. The potential implications of hrHPV testing and some other biomarkers deduced from this model for cervical screening and the clinical management of CIN disease are also discussed. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Helicobacter infection and gastric neoplasia
Authors: Peek Richard M , Crabtree Jean E
Published: December 2005

Chronic gastritis induced by Helicobacter pylori is the strongest known risk factor for adenocarcinoma of the distal stomach, yet only a minority of people who harbour this organism ever develop cancer. H. pylori isolates possess substantial genotypic diversity, which engenders differential host inflammatory responses that influence clinical outcome. H. pylori strains that possess the cag pathogenicity island and secrete a functional cytotoxin induce more severe gastric injury and further augment the risk for developing distal gastric cancer. However, carcinogenesis is also influenced by host genetic diversity, particularly involving immune response genes such as IL‐1ß and TNF‐α. It is important to gain insight into the pathogenesis of H. pylori‐induced gastritis and adenocarcinoma, not only to develop more effective treatments for gastric cancer, but also because it might serve as a paradigm for the role of chronic inflammation in the genesis of other malignancies that arise within the gastrointestinal tract. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Morbilliviruses and human disease
Authors: Rima Bertus K , Duprex W Paul
Published: December 2005

Morbilliviruses are a group of viruses that belong to the family Paramyxoviridae. The most instantly recognizable member is measles virus (MV) and individuals acutely infected with the virus exhibit a wide range of clinical symptoms ranging from a characteristic mild self‐limiting infection to death. Canine distemper virus (CDV) and rinderpest virus (RPV) cause a similar but distinctive pathology in dogs and cattle, respectively, and these, alongside experimental MV infection of primates, have been useful models for MV pathogenesis. Traditionally, viruses were identified because a distinctive disease was observed in man or animals; an infectious agent was subsequently isolated, cultured, and this could be used to recapitulate the disease in an experimentally infected host. Thus, satisfying Koch's postulates has been the norm. More recently, particularly due to the advent of exceedingly sensitive molecular biological assays, many researchers have looked for infectious agents in disease conditions for which a viral aetiology has not been previously established. For these cases, the modified Koch's postulates of Bradford Hill have been developed as criteria to link a virus to a specific disease. Only in a few cases have these conditions been fulfilled. Therefore, many viruses have over the years been definitely and tentatively linked to human diseases and in this respect the morbilliviruses are no different. In this review, human diseases associated with morbillivirus infection have been grouped into three broad categories: (1) those which are definitely caused by the infection; (2) those which may be exacerbated or facilitated by an infection; and (3) those which currently have limited, weak, unsubstantiated or no credible scientific evidence to support any link to a morbillivirus. Thus, an attempt has been made to clarify the published data and separate human diseases actually linked to morbilliviruses from those that are merely anecdotally associated. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Rational design of gene‐based vaccines
Authors: Barouch Dan H
Published: December 2005

Vaccine development has traditionally been an empirical discipline. Classical vaccine strategies include the development of attenuated organisms, whole killed organisms, and protein subunits, followed by empirical optimization and iterative improvements. While these strategies have been remarkably successful for a wide variety of viruses and bacteria, these approaches have proven more limited for pathogens that require cellular immune responses for their control. In this review, current strategies to develop and optimize gene‐based vaccines are described, with an emphasis on novel approaches to improve plasmid DNA vaccines and recombinant adenovirus vector‐based vaccines. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
The function of immunoglobulin A in immunity
Authors: Woof Jenny M , Kerr Michael A
Published: December 2005

The vast surfaces of the gastrointestinal, respiratory, and genitourinary tracts represent major sites of potential attack by invading micro‐organisms. Immunoglobulin A (IgA), as the principal antibody class in the secretions that bathe these mucosal surfaces, acts as an important first line of defence. IgA, also an important serum immunoglobulin, mediates a variety of protective functions through interaction with specific receptors and immune mediators. The importance of such protection is underlined by the fact that certain pathogens have evolved mechanisms to compromise IgA‐mediated defence, providing an opportunity for more effective invasion. IgA function may also be perturbed in certain disease states, some of which are characterized by deposition of IgA in specific tissues. This review details current understanding of the roles played by IgA in both health and disease. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.