bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiple pole residue approach for 3D BEM analysis of mathematical degenerate and non‐degenerate materials
Authors: Buroni Federico C. , Ortiz Jhonny E. , Sáez Andrés 
Published: December 2010

AbstractIn this paper we develop an alternative boundary element method (BEM) formulation for the analysis of anisotropic three‐dimensional (3D) elastic solids. Our implementation is based on the derivation of explicit expressions for the fundamental solution displacements and tractions, of general validity for any class of anisotropic materials, by means of Stroh formalism and Cauchy's residue theory. The resulting fundamental solution remains valid for mathematical degenerate cases when Stroh's eigenvalues are coincident, meanwhile it does not exhibit numerical instabilities for quasi‐degenerate cases when Stroh's eigenvalues are nearly equal. A multiple pole residue approach is followed, leading to general explicit expressions to evaluate the traction fundamental solution for poles of m‐multiplicity. Despite the existence of general displacement solutions in the literature, and for the sake of completeness, the same approach as for the traction solution is considered to derive the displacement fundamental solution as well. Based on these solutions, an explicit BEM approach for the numerical solution of 3D linear elastic problems for solids with general anisotropic behavior is presented. The analysis of cracked anisotropic solids is also considered. Details on the numerical implementation and its validation for degenerate cases are discussed. Copyright © 2010 John Wiley & Sons, Ltd.
Higher‐order extended finite elements with harmonic enrichment functions for complex crack problems
Authors: Mousavi S. E. , Grinspun E. , Sukumar N. 
Published: December 2010

AbstractIn this paper, we analyze complex crack problems in elastic media using harmonic enrichment functions in a higher‐order extended finite element implementation. The numerically computed enrichment function of a crack is the solution of the Laplace equation with discontinuous Dirichlet boundary condition along the crack, and its interaction with branches or other cracks is realized by imposing vanishing Neumann boundary conditions along those cracks. The classical finite element displacement approximation is enriched by adding the enrichment function of a crack through the framework of partition of unity. A nested subgrid mesh is used in the Laplace solve with a rasterized approximation of a crack, which simplifies the numerical integration—no partitioning of finite elements is required. Harmonic enrichment functions readily permit the extension to handle multiple interacting and branched cracks without any special treatment around the junction points. Several numerical examples are presented that affirm the accuracy and effectiveness of the method when applied to complex crack configurations under mixed‐mode loading conditions. Copyright © 2010 John Wiley & Sons, Ltd.
Dispersion error reduction for acoustic problems using the edge‐based smoothed finite element method (ES‐FEM)
Authors: He Z. C. , Cheng A. G. , Zhang G. Y. , Zhong Z. H. , Liu G. R. 
Published: December 2010

AbstractThe paper reports a detailed analysis on the numerical dispersion error in solving 2D acoustic problems governed by the Helmholtz equation using the edge‐based smoothed finite element method (ES‐FEM), in comparison with the standard FEM. It is found that the dispersion error of the standard FEM for solving acoustic problems is essentially caused by the ‘overly stiff’ feature of the discrete model. In such an ‘overly stiff’ FEM model, the wave propagates with an artificially higher ‘numerical’ speed, and hence the numerical wave‐number becomes significantly smaller than the actual exact one. Owing to the proper softening effects provided naturally by the edge‐based gradient smoothing operations, the ES‐FEM model, however, behaves much softer than the standard FEM model, leading to the so‐called very ‘close‐to‐exact’ stiffness. Therefore the ES‐FEM can naturally and effectively reduce the dispersion error in the numerical solution in solving acoustic problems. Results of both theoretical and numerical studies will support these important findings. It is shown clearly that the ES‐FEM suits ideally well for solving acoustic problems governed by the Helmholtz equations, because of the crucial effectiveness in reducing the dispersion error in the discrete numerical model. Copyright © 2010 John Wiley & Sons, Ltd.
Detection and characterization of transport barriers in complex flows via ridge extraction of the finite time Lyapunov exponent field
Authors: Senatore Carmine , Ross Shane D. 
Published: December 2010

AbstractThis paper proposes an algorithm to detect and characterize ridges in the finite time Lyapunov exponent (FTLE) field obtained from a continuous dynamical system or flow. These ridges represent time‐dependent separatrices of the flow and are also called Lagrangian coherent structures (LCS). LCS have been demonstrated to be an effective way to analyze realistic time‐chaotic flows, although they can be quite complex. Therefore, in order to exploit the information that LCS can provide it is important to locate and characterize these structures in a systematic way. This can be accomplished by interpreting the FTLE as a height field and detecting the LCS as ridges of this graph. Methodologies developed in the image processing framework are integrated with dynamical system inspired approaches in order to characterize ridge strength and location. The main novel contribution of the proposed algorithm is a scheme to connect sets of points into curves or surfaces (rather than distributions of points around a ridge axis) and classify these curves or surfaces using a dynamical systems measure of strength. This approach provides the capability to track ranked LCS in space and time. The results are presented for a simple analytical model and noisy LCS from realistic three‐dimensional geophysical fluid data. Copyright © 2010 John Wiley & Sons, Ltd.
Late Epipaleolithic hunters of the central Taurus: Faunal remains from Direkli Cave, Kahramanmaraş, Turkey
Authors: Arbuckle B. S. , Erek C. M. 
Published: December 2010

ABSTRACTNewly initiated research at Direkli cave is helping to define an initial understanding of Epipaleolithic hunter‐gatherer traditions in the central Taurus region of southern Turkey. Detailed analysis of the Direkli faunal assemblage suggests that in the late Epipaleolithic the cave functioned as a short‐term logistical camp used to intercept wild goats (Capra aegagrus) in the high peaks around the cave, primarily in the late summer and fall. In addition, hunters opportunistically exploited deer and a variety of other small taxa, including tortoise, in the forested vicinity of the site. Evidence for low intensity and seasonal occupation of the cave indicates that Epipaleolithic foragers in the region were highly mobile, utilised a wide range of resources, but primarily scheduled use of the cave in order to exploit high ranked wild goat resources. This represents the first window into the nature of foraging systems just prior to the emergence of agricultural economies in this important region of Turkey. Copyright © 2010 John Wiley & Sons, Ltd.
Implications of age variation and sexual dimorphism in modern equids for Middle Pleistocene equid taxonomy
Authors: van Asperen E. N. 
Published: December 2010

ABSTRACTInterspecific variation in the equid lineage is limited when compared with other large mammal lineages, while a considerable amount of intraspecific ecomorphological variation occurs. This has led to considerable debate regarding the taxonomic status of palaeontological and archaeological equid remains. The possible confounding impact of sex and age variation on analyses of archaeological equid remains has so far remained untested. This could be especially problematic when it is unknown whether an assemblage contains more than one equid species, breed or hybrid. Here, sex and age variation in modern equid species is examined and compared to variation in Pleistocene equid assemblages from northwest Europe. Sex variation in the longbones of modern equid species was found to be lower than variation over time. Similarly, age variation in dental elements of the same species is predominantly lower than diachronic variation, although caution needs to be taken when an archaeological assemblages consists mostly of elements at a similar wear stage.To assess whether late Middle Pleistocene caballoid horse fossils should be assigned to multiple species or be considered to form a monospecific group, the coefficients of variation for measurements on fossil horse remains were compared with those for modern equid specimens. Results indicate that the fossil assemblages are similarly variable to samples of modern material. Taken as a whole, the late Middle Pleistocene caballoid horse lineage is equally variable to an assemblage of modern ponies of a variety of different breeds. This implies that the variation observed between samples dating from different parts of the Middle Pleistocene can be characterised as intraspecific variation within a single species reflecting ecomorphological adaptations to the changeable Pleistocene climate. Copyright © 2010 John Wiley & Sons, Ltd.
Large lytic cranial lesions: A differential diagnosis from pre‐Angkorian Cambodia
Authors: Domett K.M. , Buckley H.R. 
Published: December 2010

ABSTRACTA late pre‐Angkorian period, c. 350 BC ‐ 200 AD, cemetery has been excavated in the village of Phum Snay, in northwestern Cambodia. In addition to the cemetery sample, a large sample of stratigraphically unprovenanced human skeletal material was uncovered in the village through extensive looting over the last 5–10 years. Both sample sets were available for study but the latter is comprised of only isolated bone elements. The differential diagnosis of the cause of lesions in one isolated cranial vault from this sample is presented here. Widespread, primarily lytic, lesions are concentrated on the frontal and anterior parietal bones, with an additional large lesion on the occipital bone. Lesions vary in size ranging from approximately 5–30 mm in diameter. A detailed description of these lesions is given and a differential diagnosis is presented that includes infectious disease, such as osteomyelitis, tuberculosis and treponemal disease, and also several forms of cancer including metastatic carcinoma, meningioma and multiple myeloma, and finally Langerhans Cell Histiocytosis. The diagnosis is difficult, given the lack of material, but it is suggested that one of the forms of Langerhans Cell Histiocytosis is the most likely candidate. The presence of such large and diffuse lesions is unusual in prehistoric Southeast Asia so the significance of this is also discussed. Copyright © 2010 John Wiley & Sons, Ltd.
Microbial desulfurization of SBR ground rubber by Sphingomonas sp. and its utilization as filler in NR compounds
Authors: Jiang Guangming , Zhao Suhe , Li Wenji , Luo Jingyuan , Wang Yaqin , Zhou Quansheng , Zhang Cuiru 
Published: December 2010

AbstractMicrobial desulfurization of waste tyre rubber has been investigated with great efforts since 1990s, because waste rubber has created serious ecological and environmental problems. A microbial desulfurization technique for SBR ground rubber has been developed by a novel sulfur‐oxidizing bacterium Sphingomonas sp. The adaptability of Sphingomonas sp. with SBR ground rubber was tested with the amounts of SBR ground rubber varying from 0.5 to 4% g/l. The sol fraction of desulfurized SBR ground rubber increased 70%, compared with SBR ground rubber without desulfurization. Fourier transform infrared spectroscopy‐attenuated total reflectance (FTIR‐ATR) spectrum and X‐ray photoelectron spectroscopy (XPS) analysis of the desulfurized surface of vulcanized SBR flakes revealed that not only the oxidation of crosslinked SS and SC bonds, but also the rupture of CC double bonds had happened to SBR vulcanizates during microbial desulfurization. The cure characteristics, such as scorch time and optimum cure time of natural rubber (NR) vulcanizates filled, were found to decrease with increasing contents of desulfurized SBR ground rubber, due to some reactive groups on its surface. NR vulcanizates filled with desulfurized SBR ground rubber had lower crosslink density and hardness, higher tensile strength and elongation at break, compared with those filled with SBR ground rubber of the same amount. Dynamic mechanical properties indicated that there were better crosslink distribution and stronger interfacial bonding between NR matrix and desulfurized SBR ground rubber. Scanning electron microscope (SEM) photographs showed that the fracture surfaces of NR vulcanizates filled with desulfurized SBR ground rubber had more smooth morphologies. Copyright © 2010 John Wiley & Sons, Ltd.
Ceramic nanofibers fabricated by electrospinning and their applications in catalysis, environmental science, and energy technology
Authors: Dai Yunqian , Liu Wenying , Formo Eric , Sun Yueming , Xia Younan 
Published: December 2010

AbstractThis paper provides a brief review of current research activities that focus on the fabrication of ceramic nanofibers by electrospinning, as well as their applications in various areas. We begin with a brief introduction to electrospinning in the context of ceramic nanofibers, and the methods for preparing aligned and/or hollow nanofibers. We then discuss approaches to the fabrication of nanofibers with a hierarchical structure. We continue with a highlight of some recent applications enabled by electrospun ceramic nanofibers, with a focus on three areas: catalysis, environmental science, and energy technology, which are expected to become the most important and exciting subjects of research in this century. In the end, we conclude this review with some perspectives on the future directions and implications for this new class of functional nanomaterials. Copyright © 2010 John Wiley & Sons, Ltd.
Hydrogels for in situ encapsulation of biomimetic membrane arrays
Authors: Ibragimova Sania , Stibius Karin , Szewczykowski Piotr , Perry Mark , Bohr Henrik , Hélix‐Nielsen Claus 
Published: December 2010

AbstractHydrogels are hydrophilic, porous polymer networks that can absorb up to thousands of times their own weight in water. They have many potential applications, one of which is the encapsulation of freestanding black lipid membranes (BLMs) for novel separation technologies or biosensor applications. We investigated gels for in situ encapsulation of multiple BLMs formed across apertures in a hydrophobic ethylene tetrafluoroethylene (ETFE) support. The encapsulation gels consisted of networks of poly(ethylene glycol)‐dimethacrylate or poly(ethylene glycol)‐diacrylate polymerized using either a chemical initiator or a photoinitiator. The hydrogels were studied with regards to volumetric stability, porosity, and water permeability. All hydrogels had pore sizes around 7 nm with volumetric changes >2% upon crosslinking. Photoinitiated hydrogels had a lower hydraulic water permeability compared to chemically initiated hydrogels; however, for all hydrogels the permeability was several‐fold higher than the water permeability of conventional reverse osmosis (RO) membranes. Lifetimes of freestanding BLM arrays in gel precursor solutions were short compared to arrays formed in buffer. However, polymerizing (crosslinking) the gel stabilized the membranes and resulted in BLM arrays that remained intact for days. This is a substantial improvement over lifetimes for freestanding BLM arrays. Optical images of the membranes and single channel activity of incorporated gramicidin ion channels showed that the lipid membranes retained their integrity and functionality after encapsulation with hydrogel. Our results show that hydrogel encapsulation is a potential means to provide stability for biomimetic devices based on functional proteins reconstituted in biomimetic membrane arrays. Copyright © 2010 John Wiley & Sons, Ltd.
Synthesis and characterization of imidized poly(styrene‐maleic anhydride) nanoparticles in stable aqueous dispersion
Authors: Samyn Pieter , Deconinck Marlies , Schoukens Gustaaf , Stanssens Dirk , Vonck Leo , Van den Abbeele Henk 
Published: December 2010

AbstractOrganic nanoparticles are synthesized by partial imidization of high‐molecular weight styrene(maleic‐anhydride) with 26 to 34 mol% maleic anhydride, in aqueous environment and presence of ammonium hydroxide. The nanoparticle dispersions have a maximum solid content of 35 wt% and good stability that critically depends on the ratio of imidized and ammonolyzed maleic anhydride moieties. The deprotonated residual maleic anhydride moieties provide dispersion stability at pH > 4, while protonation at pH < 4 causes nanoparticle sedimentation. After presentation of the synthesis conditions, the imidization reaction is characterized by FT‐IR and Raman spectroscopy, followed by thermal analysis (TGA, DSC), and morphological characterization (DLS, SEM, TEM, AFM). The reaction conditions were optimized by physical characterization of various dispersions, and finally nanoparticles could be obtained with a maximum degree of imidization of 77% in dispersed conditions, or 90 to 95% after drying that are favorable for coating applications.
Copyright © 2010 John Wiley & Sons, Ltd.
Synthesis and swelling characteristics of a pH‐responsive guar gum‐g‐poly(sodium acrylate)/medicinal stone superabsorbent composite
Authors: Zhai Naihua , Wang Wenbo , Wang Aiqin 
Published: December 2010

AbstractA series of pH‐responsive superabsorbent composites were synthesized by the free‐radical grafting copolymerization of natural guar gum (GG), partially neutralized acrylic acid (NaA), and medicinal stone (MS) using ammonium persulfate (APS) as the initiator and N,N′‐methylene‐bis‐acrylamide (MBA) as the crosslinker. The structure, surface morphologies, and thermal stability of the developed composites were characterized by FTIR spectra, SEM, and TGA techniques, respectively. The effects of various saline, surfactant, and dye solutions on swelling properties were investigated, and the pH‐responsivity was also evaluated. Results indicated that NaA had been grafted onto GG macromolecular chains and MS participated in the polymerization reaction. The incorporation of MS obviously improved the surface structure, thermal stability, water absorption capacity, and rate. Multivalent saline, cationic surfactant, and dye showed more remarkable effect on the water absorption than did monovalent or anionic ones. The composites showed excellent responsive properties and reversible On–Off switching characteristics in various pH buffer solutions, which provided great possibility to extend the application domain of the superabsorbent composites. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers
Nonisothermal transient filling simulation of fiber suspended viscoelastic liquid in a center‐gated disk
Authors: Park Jang Min , Kwon Tai Hun 
Published: December 2010

AbstractThe present study numerically investigates a fiber orientation in injection‐molded short fiber reinforced thermoplastic composite by using a rheological model, which includes the nonlinear viscoelasticity of polymer and the anisotropic effect of fiber in the total stress. A nonisothermal transient‐filling process for a center‐gated disk geometry is analyzed by a finite element method using a discrete‐elastic‐viscous split stress formulation with a matrix logarithm for the viscoelastic fluid flow and a streamline upwind Petrov–Galerkin method for convection‐dominated problems. The numerical analysis result is compared to the experimental data available in the literature in terms of the fiber orientation in center‐gated disk. The effects of the fiber coupling and the slow‐orientation kinetics of the fiber are discussed. Also, the effect of the injection‐molding processing condition is discussed by varying the filling time and the mold temperature. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers
Application of NMR‐based metabolomics to the investigation of salt stress in maize (Zea mays)
Authors: Gavaghan Claire L. , Li Jia V. , Hadfield Stephen T. , Hole Stephen , Nicholson Jeremy K. , Wilson Ian D. , Howe Peter W. A. , Stanley Paul D. , Holmes Elaine 
Published: December 2010

AbstractIntroduction – High salinity, caused by either natural (e.g. climatic changes) or anthropic factors (e.g. agriculture), is a widespread environmental stressor that can affect development and growth of salt‐sensitive plants, leading to water deficit, the inhibition of intake of essential ions and metabolic disorders.Objective – The application of an NMR‐based metabolic profiling approach to the investigation of saline‐induced stress in Maize plants is presented.Methodology – Zea Maize seedlings were grown in either 0, 50 or 150 mM saline solution. Plants were harvested after 2, 4 and 6 days (n = 5 per class and time point) and 1H NMR spectroscopy was performed separately on shoot and root extracts. Spectral data were analysed and interpreted using multivariate statistical analyses.Results – A distinct effect of time/growth was observed for the control group with relatively higher concentrations of acetoacetate at day 2 and increased levels of alanine at days 4 and 6 in root extracts, whereas concentration of alanine was positively correlated with the shoot extracts harvested at day 2 and trans‐aconitic acid increased at days 4 and 6. A clear dose‐dependent effect, superimposed on the growth effect, was observed for saline treated shoot and root extracts. This was correlated with increased levels of alanine, glutamate, asparagine, glycine‐betaine and sucrose and decreased levels of malic acid, trans‐aconitic acid and glucose in shoots. Correlation with salt‐load shown in roots included elevated levels of alanine, γ‐amino‐N‐butyric acid, malic acid, succinate and sucrose and depleted levels of acetoacetate and glucose.Conclusions – The metabolic effect of high salinity was predominantly consistent with osmotic stress as reported for other plant species and was found to be stronger in the shoots than the roots. Using multivariate data analysis it is possible to investigate the effects of more than one environmental stressor simultaneously. Copyright © 2010 John Wiley & Sons, Ltd.
Validation of the national health insurance research database with ischemic stroke cases in Taiwan
Authors: Cheng Ching‐Lan , Kao Yea‐Huei Yang , Lin Swu‐Jane , Lee Cheng‐Han , Lai Ming Liang 
Published: December 2010

AbstractObjectiveThe National Health Insurance Research Database (NHIRD) is commonly used for pharmacoepidemiological research in Taiwan. This study evaluated the validity of the database for patients with a principal diagnosis of ischemic stroke.Study design and methodsThis cross‐sectional study compares records in the NHIRD with those in one medical center. Patients hospitalized for ischemic stroke in 1999 were identified from both databases. The discharge notes, laboratory data, and medication orders during admission and the first discharge visit were reviewed to validate ischemic stroke diagnoses and aspirin prescribing in the NHIRD. Agreement between the two databases in comorbidities of ischemic stroke diagnosis was evaluated using ICD‐9 codes.ResultsThree hundred and seventy two cases were identified from the NHIRD; among them, 364 cases (97.85%) were confirmed as ischemic stroke by radiology examination and clinical presentation. Among these confirmed cases, 344 (94.51%) were assigned ‘ischemic stroke’ as the principal diagnosis in the NHIRD. The overall agreement of comorbid diagnoses between the databases was 48.39%. The PPV for selected conditions also varied widely, from 0.50 for fracture to 1.00 for colon cancer. The accuracy of recorded aspirin prescriptions was higher in first post‐discharge visits (PPV = 0.94) than during hospitalization (PPV = 0.88).ConclusionThe accuracy of the NHIRD in recording ischemic stroke diagnoses and aspirin prescriptions was high, and the NHIRD appears to be a valid resource for population research in ischemic stroke. Copyright © 2010 John Wiley & Sons, Ltd.