bluuebunny/crossref_metadata_2025_split huggingface dataset:
Approximation of scattered data using the lifting scheme
Authors: Stahl Dominik , Damm Tobias 
Published: December 2012

AbstractIn this note we briefly explain a method to approximate scattered data. One major task here is to solve a least squares problem. Demanding that at least constant scattered data is approximated correctly, implies the use of Tikhonov regularizations satisfying a simple constraint. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the dynamic behaviour of fluid‐saturated soil within the framework of elasto‐plasticity
Authors: Schenke Maik , Markert Bernd , Ehlers Wolfgang 
Published: December 2012

AbstractPhenomena related to porous media dynamics, such as wave propagation and liquefaction, are encountered in many engineering applications, especially, in geomechanics and earthquake engineering. Drawing our attention to fluid‐saturated granular materials with heterogeneous microstructures, the modelling is carried out within a continuum‐mechanical framework by exploiting the well‐established macroscopic Theory of Porous Media (TPM) together with thermodynamically consistent constitutive equations. In this regard, the solid skeleton of the soil is described as an elasto‐plastic material. The underlying equations are discretised and implemented into the coupled porous‐media finite‐element solver PANDAS and linked to the commercial finite‐element package Abaqus through a general interface. This coupling allows the definition of complex intial‐boundary‐value problems through Abaqus, thereby using the state‐of‐the‐art material models of PANDAS. In order to get a detailed understanding of the behaviour of the underlying soil model under dynamic loading conditions, a cyclic torsion test is numerically investigated. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flow Modeling in Rock Fracture for Long Time Simulation of Geothermal Reservoirs
Authors: Ostermeyer Georg‐Peter , Srisupattarawanit Tarin 
Published: December 2012

AbstractThe exploitation of geothermal power is an energy source with great potential for the future. But the exploration and development of deep geothermal energy is connected with high cost and risk, these require a reliable numerical prediction. The analysis of geothermal reservoir is usually interested in long time physical properties (e.g. 50–100 years). Typical CFD simulation tool could be used somehow, but the computational effort may be limited due to incompatibility of small scale heterogeneities. Here we developed flow modeling in rock fracture, which describe the different characteristic flow in different dimension. The fluid flow in tube is described by one dimensional flow (1D flow), while flow in rock fracture is modeled as two dimensional flow (2D flow) on fracture plane. The 1D flow in tube and 2D flows in fracture are coupled to represent three dimensional flows in reservoirs. The solution of coupling system (1D and 2D flow) is obtained by iterative procedure, while the flow inside 2D fracture is calculated by cellular automaton. This algorithm is relatively fast for calculating flow inside rock fracture, especially for long time behavior of 3D–geothermal reservoir. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simultaneous identification of material and geometry parameters in view of structured specimen
Authors: Wulf Hans , Schellenberg Dirk , Ihlemann Jörn 
Published: December 2012

AbstractA variety of tools for the identification of material parameters from inhomogeneous experiments already exist. These either use an FE solver as a subroutine or are directly integrated into an FE program. Thereby, it is usually assumed that the material parameters are constant among the whole specimen. This condition is not met when considering structured specimen which arise when investigating biological tissue or work pieces produced by massive forming, for instance. Here, the considered domain consists of different material types or areas with different material parameters. These are modeled by using multiple material domains. Frequently, the exact shape of the material domains is unknown and must identified as well. Both aspects, shape of the material domains and material parameters, influence the behaviour of the specimen considerably. Therefore, a separate identification yields poor results. In this paper an algorithm for the combined identification of material and geometrical properties is presented. In addition, the application on an academic example with two material domains using a simple porous media material model is demonstrated. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computing roots for the modelling of waves in acoustic waveguides
Authors: Walther Andrea , Bause Fabian , Henning Bernd 
Published: December 2012

AbstractComputer aided simulation of guided acoustic waves in single‐ or multilayered waveguides is an essential tool for several applications of acoustics and ultrasonics (i.e. pipe inspection, noise reduction). To simulate wave propagation in geometrically simple waveguides (plates or rods), one may employ the analytical Global Matrix Method [3]. This requires the computation of all roots of the determinate of a certain submatrix. The evaluation of all real or even complex roots is actually the methods most concerning restriction. Previous approaches based on so called mode‐tracers which use the physical phenomenon that solutions (roots) appear in a certain pattern (waveguide modes) and thus use known solutions to limit the root finding algorithms search space with respect to consecutive solutions. As the limitation of the search space might be unstable in some cases, we propose to replace the mode‐tracer with a suitable version of an interval Newton method based on INTLAB [4]. To apply this interval based method, we extended the interval and derivative computation provided by INTLAB such that corresponding information is also available for Bessel functions used in the circular model (rods) of acoustic waveguides. We present numerical results of a simple acoustic waveguide and discuss extensions required for more realistic scenarios. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parallel Simulation of Biological Soft Tissue
Authors: Fischle Andreas , Klawonn Axel , Rheinbach Oliver , Schröder Jörg 
Published: December 2012

AbstractNumerical results of nonlinear parallel simulations of soft biological tissue are shown using the FETI‐DP method. An hyperelastic model is considered which incorporates almost incompressibility as well as anisotropy. An arterial geometry reconstructed from ultrasound data is used. Numerical scalability is shown using up to 4096 cores of a Cray XT6. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Similarity of Indefinite Sturm‐Liouville Operators
Authors: Möws Roland 
Published: December 2012

AbstractIn this note we give sufficient conditions for the coefficients of a singular Sturm‐Liouville operator on ℝ with an indefinite weight function such that the operator is similar to a self‐adjoint operator in the Hilbert space L2(ℝ). (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of Beals spaces
Authors: Micheler Till 
Published: December 2012

AbstractIn the last decade a class of spaces introduced by Richard Beals in 1965 was frequently used as “natural” domains of symmetric properly elliptic differential operators in extension theory methods in Hilbert spaces. In the present note we use some fundamental results from Lions and Magenes to show that the so‐called Beals spaces coincide with usual Sobolev spaces endowed with the graph norm of a properly elliptic differential operator. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Drude‐Born‐Fedorov Model for Chiral Electromagnetic Media
Authors: Picard Rainer , Freymond Henrik 
Published: December 2012

AbstractElectro‐magnetic wave propagation in more complex linear materials such as bi‐anisotropic media have come to a considerable attention within the last fifteen to twenty years. The Drude‐Born‐Fedorov model has been extensively studied mostly in the time‐harmonic case as a model for chiral media. In the physically relevant time‐dependent case the record is much less convincing. In this paper we focus on this case and analyze the Drude‐Born‐Fedorov model in the light of recently developed Hilbert space approach to evolutionary problems. The solution theory will be developed in the framework of extrapolation spaces (Sobolev lattices). (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Topology synthesis of large‐displacement compliant mechanisms with specific output motion paths
Authors: Dirksen Frank , Berg Thomas , Lammering Rolf , Zohdi Tarek I. 
Published: December 2012

AbstractThis paper presents the synthesis of large‐displacement compliant mechanisms (CM) with specific output motion paths. For this purpose, a robust and efficient staggered topology optimization scheme, based on the optimality criteria (OC) method and the globally convergent method of moving asymptotes (GCMMA), is proposed, described and implemented to maximize the output motion of the design CM for a user‐specified motion path. Nonlinear geometric effects are taken into account to ensure proper modelling of large displacements occurring in CM. Different setups of a vector‐based formulation are described and benchmarked. Numerical results for a gripping mechanism model problem show that the presented approach generates path‐following compliant mechanisms in an efficient and systematic manner. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Global sensitivity analysis for the efficient solution of optimization problem in design process
Authors: Reuter Uwe , Mehmood Zeeshan , Liebscher Martin 
Published: December 2012

AbstractApplication of the methods of global sensitivity analysis in design process arises due to the complexity associated with structural optimization, e. g., in the automobile industry for an optimal vehicle structure for crash load cases. Usually, thousands of variants are considered for a vehicle design project and each variant represents a combination of a number of model parameters. The computation time for a single variant ranges from several hours to days. To reduce the complexity of the optimization problem, the significant parameters should be identified but possibly with a very few sample points. Since most of the available global sensitivity methods require a good approximation of the model response, a relatively large number of sample points is usually required for the surrogate model. In this contribution, an overview of state‐of‐the‐art methods of global sensitivity analysis is given and an alternative idea is proposed to avoid full approximation of the model response. Instead, only the approximation of the level sets of the model response is used to derive sensitivity measures. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A rate independent polycrystal model and a specific application for asymmetrically rolled aluminium sheets
Authors: Alves de Sousa Ricardo 
Published: December 2012

AbstractThe asymmetric rolling process differs from conventional rolling through the use of different roll circumferential velocities or diameters. Using proper parameters, asymmetric rolling imposes intense shear deformations across the sheet thickness, leading not only to the occurrence of shear texture, but also to grain refinement [1]. In fact, some shear texture components are known to improve plastic strain ratio values, and thus formability.In this work, the rate‐independent polycrystal model of Gambin [2] was efficiently implemented and applied to predict the mechanical response of distinct texture components that appear after asymmetrical rolling. For FCC materials, this polycrystal plasticity model avoids the uniqueness issue related to the choice of the set of active slip systems by applying a regularized Schmid Law. Consequently, it generates yield surfaces with smooth corners where the normal vector is always uniquely defined. Also, it doesn't require the arbitrarily defined reference strain rate commonly used in the viscous‐approximation of rate‐dependent models.For validation purposes, a 1050‐O sheet was subjected to tensile and shear tests. The model could accurately simulate the measured results. In the end, ideal textures components were simulated and their mechanical response was evaluated. Hence, it is stated a solid basis to justify the improvement of sheet's mechanical properties after asymmetrical rolling when compared to conventional rolling. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Particle hydrodynamics based on maximum entropy approximation
Authors: Hartmann Dirk 
Published: December 2012

AbstractIn this contribution, we propose a new particle based scheme for computational hydrodynamics. In contrast to existing particle based approaches, we use a maximum entropy approximation scheme to construct corresponding shape functions. These allow first order consistency as well as an efficient realisation of essential boundary conditions. The scheme is relative simple from an algorithmic point of view and computations can be efficiently accelerated using graphic processing units. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
LRIG1 regulates cadherin‐dependent contact inhibition directing epithelial homeostasis and pre‐invasive squamous cell carcinoma development
Authors: Lu Liwen , Teixeira Vitor H , Yuan ZhengQiang , Graham Trevor A , Endesfelder David , Kolluri Krishna , Al‐Juffali Noura , Hamilton Nicholas , Nicholson Andrew G , Falzon Mary , Kschischo Maik , Swanton Charles , Wright Nicholas A , Carroll Bernadette , Watt Fiona M , George Jeremy P , Jensen Kim B , Giangreco Adam , Janes Sam M 
Published: December 2012

AbstractEpidermal growth factor receptor (EGFR) pathway activation is a frequent event in human carcinomas. Mutations in EGFR itself are, however, rare, and the mechanisms regulating EGFR activation remain elusive. Leucine‐rich immunoglobulin repeats‐1 (LRIG1), an inhibitor of EGFR activity, is one of four genes identified that predict patient survival across solid tumour types including breast, lung, melanoma, glioma, and bladder. We show that deletion of Lrig1 is sufficient to promote murine airway hyperplasia through loss of contact inhibition and that re‐expression of LRIG1 in human lung cancer cells inhibits tumourigenesis. LRIG1 regulation of contact inhibition occurs via ternary complex formation with EGFR and E‐cadherin with downstream modulation of EGFR activity. We find that LRIG1 LOH is frequent across cancers and its loss is an early event in the development of human squamous carcinomas. Our findings imply that the early stages of squamous carcinoma development are driven by a change in amplitude of EGFR signalling governed by the loss of contact inhibition.© 2012 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
An α‐E‐catenin (CTNNA1) mutation in hereditary diffuse gastric cancer
Authors: Majewski Ian J , Kluijt Irma , Cats Annemieke , Scerri Thomas S , de Jong Daphne , Kluin Roelof JC , Hansford Samantha , Hogervorst Frans BL , Bosma Astrid J , Hofland Ingrid , Winter Marcel , Huntsman David , Jonkers Jos , Bahlo Melanie , Bernards René 
Published: December 2012

AbstractDiffuse gastric cancers typically present as late‐stage tumours and, as a result, the 5 year survival rate is poor. Some gastric cancers are hereditary and these tend to be of the diffuse type; 30–40% of hereditary diffuse gastric cancers (HDGCs) can be explained by defective germline alleles of E‐cadherin (CDH1), but for the remaining families the factors driving susceptibility remain unknown. We had access to a large HDGC pedigree with no obvious mutation in CDH1, and applied exome sequencing to identify new genes involved in gastric cancer. We identified a germline truncating allele of α‐E‐catenin (CTNNA1) that was present in two family members with invasive diffuse gastric cancer and four in which intramucosal signet ring cells were detected as part of endoscopic surveillance. The remaining CTNNA1 allele was silenced in the two diffuse gastric cancers from the family that were available for screening, and this was also true for signet ring cells identified in endoscopic biopsies. Since α‐E‐catenin functions in the same complex as E‐cadherin, our results call attention to the broader signalling network surrounding these proteins in HDGC. We also detected somatic mutations in one tumour and found substantial overlap with genes mutated in sporadic gastric cancer, including PIK3CA, ARID1A, MED12 and MED23.
Exploring the potential prognostic effect of various country‐specific health service data on all‐cause mortality using data from a large prospective study in schizophrenia
Authors: Mittoux Aurélia , Tanghøj Per , Moore Nicholas 
Published: December 2012

ABSTRACTPurposeTo explore whether the presence of specific health services impact the time to death in schizophrenia.MethodsCox's proportional hazard model was used to assess the effect of country‐specific health care variables (total health care expenditure, public health care expenditure, number of hospital beds, number of physicians, and World Health Organization ranking) on time to death in schizophrenia patients from a large multinational study. Baseline patient characteristics (history of suicide attempts and monotherapy or polytherapy at the time of study entry) were also included in the model.ResultsThe number of physicians per 10,000 persons was the only health service variable associated with time to death. Each increase of one physician increased the hazard of dying by approximately 2% (95%CI, from 0.1 to 4.1%; p = 0.044) in Europe, whereas in Asia, it seemed to decrease the hazard of dying by approximately 3.6% (95%CI, from 9.9% decrease to 3% increase; p = 0.28). The effect of region as a function of the number of physicians indicated a turning point at 23 physicians per 10,000 persons: With fewer than 23 physicians per 10,000 persons, the risk of death was higher in Asia than that in Europe (hazard ratio > 1), whereas with more than 23 physicians per 10,000 persons, it was lower in Asia than that in Europe (hazard ratio < 1).ConclusionsSome health services may have a significant prognostic effect on time to death in patients treated for schizophrenia, especially in Europe. The reasons for this need to be identified. Copyright © 2012 John Wiley & Sons, Ltd.
Effect of functionalized nanosilica on the mechanical, dynamic‐mechanical, and morphological performance of polycarbonate/nanosilica nanocomposites
Authors: Biswal Manoranjan , Mohanty Smita , Nayak Sanjay K. , Kumar P. Sudheesh 
Published: December 2012

AbstractPolycarbonate (PC)/nanosilica (nSiO2) nanocomposites were prepared by melt‐blending technique, in which surfactants are used to enhance the interfacial adhesion between nSiO2 and polymer matrix. Mechanical properties demonstrate increased Young's modulus and yield strength of modified PC/nSiO2 nanocomposites when compared with PC. Increased compatibility further indicates an effective increase in thermal stability as observed from thermogravimetric analysis. Dynamic mechanical analysis point out a reduction in Tg value with increased storage modulus. The flammability characteristics of PC/nSiO2 nanocomposites were evaluated using limiting oxygen index, whereas the morphological properties are characterized by wide‐angle X‐ray diffraction and scanning electron microscopy. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Working memory training in survivors of pediatric cancer: a randomized pilot study
Authors: Hardy Kristina K. , Willard Victoria W. , Allen Taryn M. , Bonner Melanie J. 
Published: December 2012

AbstractObjectivesSurvivors of pediatric brain tumors and acute lymphoblastic leukemia (ALL) are at increased risk for neurocognitive deficits, but few empirically supported treatment options exist. We examined the feasibility and preliminary efficacy of a home‐based, computerized working memory training program, CogmedRM, with survivors of childhood cancer.MethodsSurvivors of brain tumors or ALL (n = 20) with identified deficits in attention and/or working memory were randomized to either the success‐adapted computer intervention or a non‐adaptive, active control condition. Specifically, children in the adaptive condition completed exercises that became more challenging with each correct trial, whereas those in the non‐adaptive version trained with exercises that never increased in difficulty. All participants were asked to complete 25 training sessions at home, with weekly, phone‐based coaching support. Brief assessments were completed pre‐intervention and post‐intervention; outcome measures included both performance‐based and parent‐report measures of working memory and attention.ResultsEighty‐five percent of survivors were compliant with the intervention, with no adverse events reported. After controlling for baseline intellectual functioning, survivors who completed the intervention program evidenced significant post‐training improvements in their visual working memory and in parent‐rated learning problems compared with those in the active control group. No differences in verbal working memory functioning were evident between groups, however.ConclusionsHome‐based, computerized cognitive training demonstrates good feasibility and acceptability in our sample. Children with higher intellectual functioning at baseline appeared to benefit more from the training, although further study is needed to clarify the strength, scope, and particularly the generalizability of potential treatment effects. Copyright © 2012 John Wiley & Sons, Ltd.
Levels of distress in breast cancer survivors approaching discharge from routine hospital follow‐up
Authors: Thompson Joanne , Coleman Rob , Colwell Brigitte , Freeman Jenny , Greenfield Diana , Holmes Karen , Mathers Nigel , Reed Malcolm 
Published: December 2012

AbstractBackgroundHospital‐based breast cancer follow‐up provides reassurance to patients despite limited evidence for clinical efficacy. Although alternative models of hospital/community‐based follow‐up have yielded encouraging results, traditional hospital follow‐up continues to be offered to all patients. Survival rates continue to rise; consequently, more patients are likely to require support, as many have a limited understanding of the long‐term physical and emotional consequences of cancer and its treatment. We examine levels of psychological distress in breast cancer patients in follow‐up 2 years or more from diagnosis.MethodsThis prospective study measured psychological distress levels using standardized measures [Hospital Anxiety and Depression Scale (HADS), Clinical Outcomes for Routine Evaluation (CORE) and Measure Yourself Medical Outcomes Profile (MYMOP)]. Between January and September 2008, 323 consecutive patients were approached in outpatient clinics. Ninety‐six patients declined to participate.ResultsTwo hundred twenty‐seven patients took home patient information sheets; 172 (75%) returned completed questionnaires to assess levels of distress (HADS, CORE). MYMOP provided self‐reported data on patient symptoms. Patients reported low levels of distress in hospital‐based follow‐up, which were comparable or better than general population norms, although there was a significant minority of patients reporting high scores (n = 27, 15.7%) on HADS or CORE. There was good agreement between these two measures. All sub‐scales of CORE (except risk) correlated well with HADS for anxiety/depression. No significant changes were detected in the standardized measures. MYMOP results showed that 23.8% of respondents reported both physical and emotional symptoms.ConclusionsBreast cancer survivors reported good psychological outcomes 2 years on from diagnosis. Screening for psychological/emotional distress is a vital part of follow‐up care, which should be incorporated into UK policy. Copyright © 2012 John Wiley & Sons, Ltd.