bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catalytic Olefin Polymerization is a Mature Field. Isn't it?
Authors: Busico Vincenzo 
Published: December 2006

AbstractIn spite of the reputation to be a mature area, Ziegler‐Natta olefin polymerization continues to produce scientific and industrial breakthroughs at a surprising pace. The massive introduction of High Throughput Screening technologies has accelerated the innovation process even further. This Highlight aims at introducing the reader to a number of very recent publications in which novel metallocene and non‐metallocene (“post‐metallocene”) olefin polymerization catalysts, and new concepts of chain growth in insertion polymerization, are disclosed and elegantly and convincingly discussed.magnified image
Stimuli‐Responsive Multilayered Hybrid Nanoparticle/Polyelectrolyte Capsules
Authors: De Geest Bruno G. , Skirtach Andrei G. , De Beer Thomas R. M. , Sukhorukov Gleb B. , Bracke Lieven , Baeyens Willy R. G. , Demeester Joseph , De Smedt Stefaan C. 
Published: December 2006

AbstractGold nanoparticles (AuNP) with carboxyl groups on their surface were used in combination with PAH for the layer‐by‐layer coating of CaCO3 microparticles, followed by the dissolution of the CaCO3 core. SEM, TEM, and confocal microscopy are used to characterize the hybrid nanoparticles/polyelectrolyte capsules. As the AuNP have carboxyl groups on their surface, their charge density is pH dependent; therefore, the capsules exhibit a pH‐dependent swelling and can be deconstructed both at low and high pH. By covalent cross‐linking of the carboxyl groups of the AuNP and the amino groups of the PAH, it is possible to suppress the pH‐responsive behavior. AuNP are used as activation centers using IR light and this ability is used to release encapsulated material from the nanoparticles/polyelectrolyte capsules as well as for the enhancement of detection and imaging of such capsules by Raman microspectrosopy.magnified image
Efficient organization of information processing
Authors: Cukrowski Jacek , Fischer Manfred M. 
Published: December 2006

AbstractThe paper examines the application of the concept of economic efficiency to organizational issues of collective information processing in decision making. Information processing is modeled in the framework of the dynamic parallel processing model of associative computation with an endogenous setup cost of the processors. The model is extended to include the specific features of collective information processing in the team of decision makers which may lead to an error in data analysis. In such a model, the conditions for efficient organization of information processing are defined and the architecture of the efficient structures is considered. We show that specific features of collective decision making procedures require a broader framework for judging organizational efficiency than has traditionally been adopted. In particular, and contrary to the results available in economic literature, we show that there is no unique architecture for efficient information processing structures, but a number of various efficient forms. The results indicate that technological progress resulting in faster data processing (ceteris paribus) will lead to more regular information processing structures. However, if the relative cost of the delay in data analysis increases significantly, less regular structures could be efficient. Copyright © 2007 John Wiley & Sons, Ltd.
Hidden monopsony rents in winner‐take‐all markets—sport and economic contribution of Spanish soccer players
Authors: Garcia‐del‐Barrio Pedro , Pujol Francesc 
Published: December 2006

AbstractIn labor markets where few companies compete for many workers, economic theory predicts monopsony rents. Surprisingly, soccer clubs do not profit from the expected rents. The purpose of this study is to explain such contradictory evidence.Our model and empirical test, using data obtained from the Spanish professional soccer league for the season 2001/2002, suggests that monopsony rents that the clubs were to obtain from most of the soccer players would eventually revert to the superstars. The study also illustrates that the market value of players stems both from their sporting performance and their economic contribution. Copyright © 2007 John Wiley & Sons, Ltd.
Correction of errors in Vetschera's (2004) model of behavioral uncertainty and investment
Authors: Tularam G.A. , Soomro A.S. 
Published: December 2006

AbstractModelling of behavioural uncertainty has been a concern for researchers for some time. This paper briefly reviews modelling related to uncertainty and the focuses on the model presented by Vetschera (2004). A model of decision behaviour has been developed in the paper with regard to investment and cooperation taking into account the uncertainty and lack of information. The model is an important contribution for it focuses on situations that are not usual to the normal principle agent problems. The present review however reveals some errors in the paper. Sometimes errors may appear editorial but the same errors may lead the interested reader or researcher to inappropriate paths, particularly those who may fail to follow an argument or comprehend the underlying meanings of the equations and analytical solutions. In this manner, further work on this important topic may be hindered if researchers accept forms as presented in the paper literally as facts to further work. The main contribution of this paper is that it presents the correct forms of the mathematical aspects and procedures of the Vetschera (2004) paper. Copyright © 2007 John Wiley & Sons, Ltd.
Context is everything: Mining the normal and preneoplastic microenvironment for insights into the diet and cancer risk conundrum
Authors: Hord Norman G. , Fenton Jenifer I. 
Published: December 2006

AbstractThis review highlights the context‐dependence of epithelial carcinogenesis in order to illuminate the potential for progress in the field of diet and cancer prevention. Estimates drawn from observational epidemiology imply that diet and lifestyle changes have the potential to prevent 30–40% of cancer cases. However, the application of knowledge gleaned from observational epidemiology applied to randomized clinical trials (RCT) has yielded equivocal or negative results. Resolving this conundrum requires: (i) advances in diet assessment methodologies and the design of clinical trials; (ii) greater knowledge of the active components within foods which may impact cancer risk; and (iii) knowledge about the effects of dietary components on susceptible tissues throughout the disease process (Meyskens, F. L., Jr., Szabo, E., Diet and cancer: The disconnect between epidemiology and RCT. Cancer Epidemiol. Biomarkers Prev. 2005, 14, 1366–1369). Explicit consideration of the causal criteria will pay tangible benefits in the design of basic, clinical, and epidemiologic studies in cancer prevention. The rational identification of diet‐dependent physiologic targets for cancer prevention is best pursued by appreciating context‐dependence of epithelial carcinogenesis. Five contexts, or paradigms useful in understanding the multifactorial nature of carcinogenesis, are offered which describe the potential diet‐associated physiologic influences on normal and preneoplastic cells and tumor microenvironments. Taken together with the interactions of systemic, endocrine, and autocrine/paracrine signals that may modulate the process of carcinogenesis, we can appreciate how dietary factors may act collectively in normal tissues or at early stages of carcinogenesis to prevent cancer. Only by understanding the effect of dietary components on the cellular and stromal components of the tissue microenvironment early in the process of epithelial carcinogenesis will yield clues useful for the development of improved strategies for cancer prevention.
Toxins of cyanobacteria
Authors: van Apeldoorn Marian E. , van Egmond Hans P. , Speijers Gerrit J. A. , Bakker Guido J. I. 
Published: December 2006

AbstractBlue‐green algae are found in lakes, ponds, rivers and brackish waters throughout the world. In case of excessive growth such as bloom formation, these bacteria can produce inherent toxins in quantities causing toxicity in mammals, including humans. These cyanotoxins include cyclic peptides and alkaloids. Among the cyclic peptides are the microcystins and the nodularins. The alkaloids include anatoxin‐a, anatoxin‐a(S), cylindrospermopsin, saxitoxins (STXs), aplysiatoxins and lyngbyatoxin. Both biological and chemical methods are used to determine cyanotoxins. Bioassays and biochemical assays are nonspecific, so they can only be used as screening methods. HPLC has some good prospects. For the subsequent detection of these toxins different detectors may be used, ranging from simple UV‐spectrometry via fluorescence detection to various types of MS. The main problem in the determination of cyanobacterial toxins is the lack of reference materials of all relevant toxins. In general, toxicity data on cyanotoxins are rather scarce. A majority of toxicity data are known to be of microcystin‐LR. For nodularins, data from a few animal studies are available. For the alkaloids, limited toxicity data exist for anatoxin‐a, cylindrospermopsin and STX. Risk assessment for acute exposure could be relevant for some types of exposure. Nevertheless, no acute reference doses have formally been derived thus far. For STX(s), many countries have established tolerance levels in bivalves, but these limits were set in view of STX(s) as biotoxins, accumulating in marine shellfish. Official regulations for other cyanotoxins have not been established, although some (provisional) guideline values have been derived for microcystins in drinking water by WHO and several countries.
Fully Crosslinked Poly[cyclotriphosphazene‐co‐(4,4′‐sulfonyldiphenol)] Microspheres via Precipitation Polymerization and Their Superior Thermal Properties
Authors: Zhu Lu , Zhu Yan , Pan Yang , Huang Yawen , Huang Xiaobin , Tang Xiaozhen 
Published: December 2006

AbstractFully crosslinked, stable poly[cyclotriphosphazene‐co‐(4,4′‐sulfonyldiphenol)] (PZS) microspheres have been prepared via the polycondensation between hexachlorocyclotriphosphazene and 4,4′‐sulfonyldiphenol by precipitation polymerization. The diameter of the PZS microspheres ranged from 0.6 to 1.0 µm with the specific surface area of the microspheres ranging from 11.7 to 10.1 m2 · g−1. The formation of the non‐porous microspheres was observed to obey an oligomeric species absorbing mechanism. The fully crosslinked chemical structure of the PZS microspheres were determined by IR, CP/MAS NMR, XRD, and EDX. No glass‐transition temperature was observed and the onset of the thermal‐degradation temperature was 542 °C. Thermal stability of the PZS microspheres by the precipitation polycondensation was significantly improved as compared with crosslinked microspheres produced by addition polymerizations.magnified image
Thermomechanical homogenization analysis of axisymmetric inelastic solids at finite strains based on an incremental minimization principle
Authors: Celigoj C. C. 
Published: December 2006

AbstractThe paper presents an attempt to extend homogenization analysis to axisymmetric solids under thermo‐ mechanical loading. In axisymmetric solids, under axisymmetric thermomechanical loading and/or torsion, on both scales, macro and micro, the displacement and rotation response is by definition independent of the cylindrical angle co‐ordinate.In homogenization analysis the deformation of the micro‐structure is driven by the deformation gradient F̄ of the macro‐structure and enhanced by a micro‐scale fluctuation field ũ, such that: x=F̄·X+ũ and in consequence F=F̄+F̃.What is new: on the micro‐scale, the fact of independence of the cylindrical angle co‐ordinate imposes the homogeneous or Taylor‐assumption on the fluctuation field ũ of the R(epresentative) V(olume) E(lement) in the radial direction, whereas the other two fluctuation fields, the torsional angle and the axial displacement , are not affected. The thermomechanical problem on the macroscale is solved via a split approach: an isentropic mechanical phase, an isogeometrical thermal phase, and—in case of inelasticity—an update phase of the internal micro‐variables.The homogenization of inelastic solid materials at finite strains is based on an incremental minimization principle, recently introduced by Miehe et al. (J. Mech. Phys. Solids 2002; 50:2123–2167).Two finite element examples demonstrate the viability of the proposed approach. Copyright © 2006 John Wiley & Sons, Ltd.
Locality constraints within multiscale model for non‐linear material behaviour
Authors: Hund Andrea , Ramm Ekkehard 
Published: December 2006

AbstractThis paper presents a two‐scale approach for the mechanical and numerical modelling of materials with microstructure‐like concrete or fibre‐reinforced concrete in the non‐linear regime. It addresses applications, where the assumption of scale separation as the basis for classical homogenization methods does not hold. This occurs when the resolution of micro and macro scale does not differ ab initio or when evolving fluctuations in the macro‐fields are in the order of the micro scale during the loading progress. Typical examples are localization phenomena. The objective of the present study is to develop an efficient solution method exploiting the physically existing multiscale character of the problem. The proposed method belongs to the superposition‐based methods with local enrichment of the large‐scale solution ū by a small‐scale part u′. The main focus of the present formulation is to allow for locality of the small‐scale solution within the large‐scale elements to achieve an efficient solution strategy. At the same time the small‐scale information exchange over the large‐scale element boundaries is facilitated while maintaining the accuracy of a refined complete solution. Thus, the emphasis lies on finding appropriate locality constraints for u′. To illustrate the method the formulation is applied to a damage mechanics based material model for concrete‐like materials. Copyright © 2006 John Wiley & Sons, Ltd.
The role of geometric stiffness in momentum and energy conserving time integration
Authors: Krenk Steen 
Published: December 2006

AbstractA momentum and energy conserving time integration algorithm is developed for the motion of elastic bodies described in terms of the quadratic Green strain. Momentum conserving algorithms are formulated from an integral of the equations of motion and energy conservation has traditionally been obtained by evaluating the contribution from the internal forces by use of a combined mean value of stresses and virtual strains on the element level. It is here demonstrated that momentum and energy conservation can be obtained from the classic central difference formulation by including an extra global term in the form of the increment of the geometric stiffness matrix over the current time step, usually directly available in global form in existing finite element programmes. The theory is derived by the use of a state‐space formulation, where this extra term is located in the same position as the viscous damping matrix, indicating that the effect of the extra incremental geometric stiffness term in the non‐linear algorithm is equivalent to a variable damping term depending on the change of the state of stress over a time increment. In the actual numerical algorithm, the new value of the velocity vector is eliminated, leaving a non‐linear equation for the displacement increment alone, followed by an explicit vector update of the velocity increment. Copyright © 2006 John Wiley & Sons, Ltd.
Improved global convergence probability using multiple independent optimizations
Authors: Schutte J. F. , Haftka R. T. , Fregly B. J. 
Published: December 2006

AbstractFor some problems global optimization algorithms may have a significant probability of not converging to the global optimum or require an extremely large number of function evaluations to reach it. For such problems, the probability of finding the global optimum may be improved by performing multiple independent short searches rather than using the entire available budget of function evaluations on a single long search. The main difficulty in adopting such a strategy is to decide how many searches to carry out for a given function evaluation budget. The basic premise of this paper is that different searches may have substantially different outcomes, but they all start with rapid initial improvement of the objective function followed by much slower progress later on. Furthermore, we assume that the number of function evaluations to the end of the initial stage of rapid progress does not change drastically from one search to another for a given problem and algorithmic setting. Therefore we propose that the number of function evaluations required for this rapid‐progress stage be estimated with one or two runs, and then the same number of function evaluations be allocated to all subsequent searches. We show that these assumptions work well for the particle swarm optimization algorithm applied to a set of difficult analytical test problems with known global solutions. For these problems we show that the proposed strategy can substantially improve the probability of obtaining the global optimum for a given budget of function evaluations. We also test a Bayesian criterion for estimating the probability of having reached the global optimum at the end of the series of searches and find that it can provide a conservative estimate for most problems. Finally, we demonstrate the approach on a particularly challenging engineering design problem constructed so as to have at least 32 widely separated local optima. Copyright © 2006 John Wiley & Sons, Ltd.
Theoretical aspects of the smoothed finite element method (SFEM)
Authors: Liu G. R. , Nguyen T. T. , Dai K. Y. , Lam K. Y. 
Published: December 2006

AbstractThis paper examines the theoretical bases for the smoothed finite element method (SFEM), which was formulated by incorporating cell‐wise strain smoothing operation into standard compatible finite element method (FEM). The weak form of SFEM can be derived from the Hu–Washizu three‐field variational principle. For elastic problems, it is proved that 1D linear element and 2D linear triangle element in SFEM are identical to their counterparts in FEM, while 2D bilinear quadrilateral elements in SFEM are different from that of FEM: when the number of smoothing cells (SCs) of the elements equals 1, the SFEM solution is proved to be ‘variationally consistent’ and has the same properties with those of FEM using reduced integration; when SC approaches infinity, the SFEM solution will approach the solution of the standard displacement compatible FEM model; when SC is a finite number larger than 1, the SFEM solutions are not ‘variationally consistent’ but ‘energy consistent’, and will change monotonously from the solution of SFEM (SC = 1) to that of SFEM (SC → ∞). It is suggested that there exists an optimal number of SC such that the SFEM solution is closest to the exact solution. The properties of SFEM are confirmed by numerical examples. Copyright © 2006 John Wiley & Sons, Ltd.
A non‐stationary covariance‐based Kriging method for metamodelling in engineering design
Authors: Xiong Ying , Chen Wei , Apley Daniel , Ding Xuru 
Published: December 2006

AbstractMetamodels are widely used to facilitate the analysis and optimization of engineering systems that involve computationally expensive simulations. Kriging is a metamodelling technique that is well known for its ability to build surrogate models of responses with non‐linear behaviour. However, the assumption of a stationary covariance structure underlying Kriging does not hold in situations where the level of smoothness of a response varies significantly. Although non‐stationary Gaussian process models have been studied for years in statistics and geostatistics communities, this has largely been for physical experimental data in relatively low dimensions. In this paper, the non‐stationary covariance structure is incorporated into Kriging modelling for computer simulations. To represent the non‐stationary covariance structure, we adopt a non‐linear mapping approach based on parameterized density functions. To avoid over‐parameterizing for the high dimension problems typical of engineering design, we propose a modified version of the non‐linear map approach, with a sparser, yet flexible, parameterization. The effectiveness of the proposed method is demonstrated through both mathematical and engineering examples. The robustness of the method is verified by testing multiple functions under various sampling settings. We also demonstrate that our method is effective in quantifying prediction uncertainty associated with the use of metamodels. Copyright © 2006 John Wiley & Sons, Ltd.
Detection of fetomaternal hemorrhage following chorionic villus sampling by Kleihauer Betke test and rise in maternal serum alpha feto protein
Authors: Katiyar Richa , Kriplani Alka , Agarwal Nutan , Bhatla Neerja , Kabra Madhulika 
Published: December 2006

AbstractObjectivesTo assess incidence and volume of fetomaternal hemorrhage (FMH) after chorionic villus sampling (CVS) by Kleihauer Betke test (KBT) and rise in maternal protein (MSAFP).MethodsA prospective study was conducted on 61 cases requiring CVS. FMH due to CVS was assessed by KBT and MSAFP.ResultsOut of 61 cases, 60 (98.36%) cases showed FMH by MSAFP while all showed FMH by KBT. Median volume of FMH detected by MSAFP was 0.06 mL (25 to 75th interquartile (IQR) 0.01 to 0.12 mL) and by KBT was 0.45 mL (25 to 75th IQR 0.09 to 0.90). Mean volume of FMH detected by MSAFP was 0.1 + 0.1424 mL and by KBT was 0.58 + 0.637 mL. Significant FMH up to 0.1 mL was found in 20 (32.8%) and 45 (60.6%) by MSAFP and KBT respectively.ConclusionMSAFP and KBT are sensitive to detect FMH. KBT estimates more FMH than MSAFP. Fifty micrograms of anti‐D is sufficient to cover FMH during CVS. Copyright © 2006 John Wiley & Sons, Ltd.
Hepatitis B vaccine and risk of autoimmune thyroid disease: a Vaccine Safety Datalink study
Authors: Yu Onchee , Bohlke Kari , Hanson Christi A. , Delaney Kristin , Rees Thomas G. , Zavitkovsky Ann , Ray Paula , Mullooly John , Black Steven B. , Benson Patti , Thompson William W. , Davis Robert L. , Jackson Lisa A. 
Published: December 2006

AbstractPurposeHepatitis B vaccine has been postulated as a possible cause of autoimmune disorders, including autoimmune thyroid diseases (ATD). Cases of Graves' disease and Hashimoto's thyroiditis, following hepatitis B vaccine have been reported to the Vaccine Adverse Events Reporting System (VAERS). To test the hypothesis that hepatitis B vaccine increases the risk of ATD, we conducted a case‐control study, within the Vaccine Safety Datalink project.MethodsWe identified potential cases of Graves' disease and Hashimoto's thyroiditis, among persons aged 18–69 years from administrative data recorded by three health maintenance organizations (HMOs) and verified cases by medical record review. Controls were frequency‐matched to cases by birth year, sex, and study site. Vaccine information was collected from administrative records, chart review, and telephone interviews with study subjects. We enrolled 355 Graves' disease cases, 418 Hashimoto's thyroiditis cases, and 1102 controls. We assessed the association between ever‐receipt of hepatitis B vaccine, as well as receipt of hepatitis B vaccine less than 1 year, 1–5 years and at least 5 years prior to the index date, and the risk of ATD.ResultsEver‐receipt of hepatitis B vaccine was not associated with risk of Graves' disease (odds ratio (OR), 0.90; 95% confidence interval (CI), 0.62–1.32) or Hashimoto's thyroiditis (OR, 1.23; 95%CI, 0.87–1.73). There was also no association between the time interval since receipt of hepatitis B vaccination and either outcome.ConclusionsWe did not observe an increased risk of Graves' disease or Hashimoto's thyroiditis, following receipt of hepatitis B vaccine. Copyright © 2007 John Wiley & Sons, Ltd.