bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical solution of large‐scale Lyapunov equations, Riccati equations, and linear‐quadratic optimal control problems
Authors: Benner Peter , Li Jing‐Rebecca , Penzl Thilo 
Published: October 2008

AbstractWe study large‐scale, continuous‐time linear time‐invariant control systems with a sparse or structured state matrix and a relatively small number of inputs and outputs. The main contributions of this paper are numerical algorithms for the solution of large algebraic Lyapunov and Riccati equations and linear‐quadratic optimal control problems, which arise from such systems. First, we review an alternating direction implicit iteration‐based method to compute approximate low‐rank Cholesky factors of the solution matrix of large‐scale Lyapunov equations, and we propose a refined version of this algorithm. Second, a combination of this method with a variant of Newton's method (in this context also called Kleinman iteration) results in an algorithm for the solution of large‐scale Riccati equations. Third, we describe an implicit version of this algorithm for the solution of linear‐quadratic optimal control problems, which computes the feedback directly without solving the underlying algebraic Riccati equation explicitly. Our algorithms are efficient with respect to both memory and computation. In particular, they can be applied to problems of very large scale, where square, dense matrices of the system order cannot be stored in the computer memory. We study the performance of our algorithms in numerical experiments. Copyright © 2008 John Wiley & Sons, Ltd.
A molecular correlate of clinicopathology in transthyretin amyloidosis
Authors: Pepys Mark B 
Published: October 2008

AbstractThe mechanisms responsible for amyloid deposition at different times and in different organs, even in individuals with the same amyloidogenic mutation, are not known. The demonstration, in hereditary systemic transthyretin Val30Met amyloidosis, that such differences are consistently associated with amyloid fibrils composed of different length transthyretin fragments sheds new light on this question and will open the way to further informative studies. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
New chemoenzymatic‐facilitated synthesis of diblock copolymers and biomedically appropriate vesicles
Authors: Li Meng , Wang Wei , Pan Si , Zhang Bao , Wang Jingyuan 
Published: October 2008

AbstractBACKGROUND: Biocatalytic approaches in polymer science are expected to further increase the diversity of polymeric materials. And the full exploitation of biocatalysis in polymer science will require the development of compatible chemoenzyme‐catalyzed methods.RESULTS: The well‐defined diblock copolymer poly(2,2,2‐trichloroethanol 10‐hydroxydecanate)‐block‐poly(glycidyl methacrylate) (P(TCE‐10‐HD)‐b‐PGMA) was obtained by combining enzymatic condensation polymerization and atom transfer radical polymerization (ATRP). P(TCE‐10‐HD) was prepared by enzymatic condensation polymerization of 10‐hydroxydecanoic acid and 2,2,2‐trichloroethanol. This CCl3‐terminated polyester permitted subsequent ATRP of glycidyl methacrylate. Kinetic studies indicated a ‘living’ controlled radical polymerization. The self‐assembly behavior of the amphiphilic diblock copolymer, in tetrahydrofuran/water, gave rise to aggregates with diameters ranging from 160 to 240 nm. The morphology of the assembly particles was studied using atomic force microscopy, transmission electron microscopy and scanning electron microscopy.CONCLUSION: To obtain the ATRP macromolecular initiator, this one‐step method is more convenient than other two‐step methods. The results of NMR, Fourier transform infrared and gel permeation chromatography analyses testified that this method is feasible. The formulated vesicles have great potential as biomedical materials. Copyright © 2008 Society of Chemical Industry
Deep‐red light‐emitting phosphorescent dendrimer encapsulated tris‐[2‐benzo[b]thiophen‐2‐yl‐pyridyl] iridium (III) core for light‐emitting device applications
Authors: Jung Kyung Moon , Kim Kyung Hwan , Jin Jung‐Il , Cho Min Ju , Choi Dong Hoon 
Published: October 2008

AbstractNew deep‐red light‐emitting phosphorescent dendrimers with hole‐transporting carbazole dendrons were synthesized by reacting tris(2‐benzo[b]thiophen‐2‐yl‐pyridyl) iridium (III) complex with carbazolyl dendrons by DCC‐catalyzed esterification. The resulting first‐, second‐, and third‐generation dendrimers were found to be highly efficient as solution‐processable emitting materials and for use in host‐free electrophosphorescent light‐emitting diodes. We fabricated a host‐free dendrimer EL device with configuration ITO/PEDOT:PSS (40 nm)/dendrimer (55 nm)/BCP (10 nm)/Alq3 (40 nm)/LiF (1 nm)/Al (100 nm) and characterized the device performance. The multilayered devices showed luminance of 561 cd/m2 at 383.4 mA/cm2 (12 V) for 15, 1302 cd/m2 at 321.3 mA/cm2 (14 V) for 16, and 422 cd/m2 at 94.4 mA/cm2 (18 V) for 17. The third‐generation dendrimer, 17 (ηext = 6.12% at 7.5 V), showed the highest external quantum efficiency (EQE) with an increase in the density of the light‐harvesting carbazole dendron. Three dendrimers exhibited considerably pure deep‐red emission with CIE 1931 (Commission International de L'Eclairage) chromaticity coordinates of x = 0.70, y = 0.30. The CIE coordinates remained very stable with the current density. The integration of rigid hole‐transporting dendrons and phosphorescent complexes provides a new route to design highly efficient solution‐processable materials for dendrimer light‐emitting diode (DLED) applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7517–7533, 2008
A facile synthetic strategy for hyperbranched polymer via combining free radical telomerization and polycondensation
Authors: Liu Jianhua , Zhan Fu , Fu Qi , Zhu Xiangyang , Shi Wenfang 
Published: October 2008

AbstractA facile strategy combining free radical telomerization and polycondensation to prepare hyperbranched polymers was developed. By selecting a suitable telogen and a vinyl monomer, the product obtained by telomerization could be regarded as an ABn type monomer for preparing a hyperbranched polymer via conventional polycondensation. The principles for selecting vinyl monomers and telogens were proposed. The feed ratio of vinyl monomer to telogen was discussed in the theory. For demonstrating the strategy, methyl (meth)acrylate (MA or MMA) and 2‐mercaptoethanol were used as a vinyl monomer and a telogen, respectively. The two‐unit adduct of MA or MMA obtained after purifying was regarded as a model ABB′ monomer. The sequential transesterification demonstrated that the carboxylate group at the terminal unit has higher reactivity than that at penultimate unit because of the different substituents at the respective α‐positions, resulting in lower degree of branching (DB) of obtained polymer. As substitutes, 2‐hydroxyethyl (meth)acrylate and thioglycolic acid were used as a vinyl monomer and a telogen, respectively. The results showed that the hyperbranched polymer obtained by using pseudo one‐pot approach had moderate DB. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7543–7555, 2008
Does the strain hardening modulus of glassy polymers scale with the flow stress?
Authors: Govaert Leon E. , Engels Tom A. P. , Wendlandt Michael , Tervoort Theo A. , Suter Ulrich W. 
Published: October 2008

AbstractUsing a generic coarse‐grained bead‐spring model, Hoy and Robbins reproduced important experimental observations on strain hardening, specifically the generally observed Gaussian strain hardening response and its dependence on network density and temperature. Moreover, their simulation results showed that the strain hardening response at different strain rates collapses to a single curve when scaled to the value of the flow stress, a phenomenon that has not yet been verified experimentally. In the present study, the proposed scaling law is experimentally investigated on a variety of polymer glasses: poly(methyl methacrylate), poly(phenylene ether), polycarbonate, polystyrene, and poly(ethylene terephthalate)‐glycol. For these polymers, true stress–strain curves in uniaxial compression were collected over a range of strain rates and temperatures and scaled to the flow stress. It was found that, generally, the curves do not collapse on a mastercurve. In all cases, the strain hardening modulus is observed to increase linearly, but not proportionally to the flow stress. The experimental data, therefore, unambiguously demonstrate that the proposed scaling law does not apply within the range of temperature and strain rate covered in this study. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2475–2481, 2008
Mapping full field deformation of auxetic foams using digital speckle photography
Authors: Chiang Fu‐pen , Uzer Gunes 
Published: October 2008

AbstractMeasuring strain in foam presents a number of challanges. In the case of polymeric foam, the material is so soft that a conventional strain gage is not applicable because the rigidity of gage and its associated glue is stronger than the foam itself. Transducers such as clip gage, etc. may not be suitable either because the strain field may not be uniform within the gage length. Thus it is desirable that a non‐contact and full field strain measurement technique be available. In this paper we introduce a speckle photography technique that is non‐contact and can measure the full field deformation of a foam specimen. We use the natural texture of the pattern. Digitized images of the foam specimen under different loads are “compared” using a special algorithm called CASI, to yield deformation maps of the specimen. Examples of applying this technique to testing PVC foam composites are presented in the paper. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Elasticity of periodic and aperiodic structures of polydisperse dimers in two dimensions at zero temperature
Authors: Narojczyk J. W. , Wojciechowski K. W. 
Published: October 2008

AbstractElastic constants of two isotropic structures formed by two‐dimensional soft dimers, built of two atoms of centres distanced by σ and interacting through site‐site n ‐inverse‐power potential, with atomic size polydispersity have been studied at zero temperature. The aperiodic structure of degenerate crystal (DC) has been compared with a periodic lattice of dimers with 3‐fold symmetry axis. The comparison performed at the density for which atoms of the dimers can form hexagonal lattice showed that, although the elastic properties of both systems are very similar, the Poisson's ratio of the degenerate structure is lower than that of the crystalline one. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Auxetic behaviour from rotating rhombi
Authors: Attard Daphne , Grima Joseph N. 
Published: October 2008

AbstractAuxeticity (i.e. negative Poisson's ratios) is associated with particular geometrical features and deformation mechanisms of a system. Among the potential systems that may exhibit such behaviour are rotating rigid units. Here we discuss how rigid rhombi of the same shape and size can be connected in two different ways to give rise to two distinct systems: the Type α and Type β rotating rhombi. We derive the mechanical properties, for the Type β system and compare it to those of the Type α to highlight the differences between the two systems namely that Type α systems are highly anisotropic and can exhibit both negative and positive Poisson's ratios which depend on the shape of the rhombi and the angle between them whereas Type β systems are isotropic with a constant in‐plane Poisson's ratio of –1. Furthermore we show that by constructing the rhombi from five truss‐type elements, where the one forming the diagonal has a different thermal expansion than the other four identical trusses, the Poisson's ratios for the Type α systems can also be made temperature dependent, in contrast with Type β systems which remain unaffected by temperature changes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sample size calculation for cluster randomized cross‐over trials
Authors: Giraudeau B. , Ravaud P. , Donner A. 
Published: October 2008

AbstractThe cluster randomized cross‐over design has been proposed in particular because it prevents an imbalance that may bring into question the internal validity of parallel group cluster trials. We derived a sample size formula for continuous outcomes that takes into account both the intraclass correlation coefficient (representing the clustering effect) and the interperiod correlation (induced by the cross‐over design). Copyright © 2008 John Wiley & Sons, Ltd.
Disintegration and violence among migrants in Germany: Turkish and Russian youths versus German youths
Authors: Baier Dirk , Pfeiffer Christian 
Published: October 2008

AbstractTurkish and Russian immigrants are the two largest groups of immigrants in Germany, but there are some important differences regarding their legal status. Although most of the Turkish adolescents were born in Germany, few of them have German citizenship. In contrast, most of the Russian youths were born outside Germany, but they mostly possess German nationality because of their status as ethnic Germans. Despite these differences, both groups show a high level of violent behavior. This article investigates the causes for the different levels of violent behavior among juvenile Russian and Turkish immigrants in comparison to German youths. On the basis of a large‐scale school survey with 14,301 respondents, the authors examine the causes for their high level of violent behavior compared to German adolescents. The theoretical basis is a combination of disintegration and socialization theory, as well as additional factors that are discussed as causes of violence in several theoretical approaches.In the empirical part of the article, the authors provide a systematic description of sources and levels of disintegration among the three youth groups. The empirical findings demonstrate that juvenile migrants are more disintegrated in several respects and that the higher level of disintegration explains some of the differences in violent behavior. But specific cultural orientations are also important in this context.
Coevolutionary dynamics of adaptive radiation for food‐web development
Authors: Ito Hiroshi C. , Shimada Masakazu , Ikegami Takashi 
Published: October 2008

AbstractTo investigate how complex food‐webs can develop through repeated evolutionary diversification, a predator–prey model was analyzed. In the model, each individual has two traits: trait x as a predator and trait y as a prey. These traits constitute a two‐dimensional phenotype space, in which the whole group of individuals are represented as a phenotype distribution. Predator–prey interactions among the phenotypes are determined by their relative positions in the phenotype space. Each phenotypic cluster was treated as a species. Each species evolves in y to escape from predation, while it evolves in x to chase their prey. Analytical investigation provided two predictions. First, coupled evolutionary diversifications of y and x may occur when the x of predators have caught up with their prey's y, which may be repeated. Second, complex food‐webs may develop when species’ competitive strengths are kept similar within the communities. If the functional response is close to the ratio‐dependent response, the competitive strengths of all species are similar when the relationship between predators and prey corresponds to the ideal free distribution (IFD). These predictions were confirmed by numerical simulations.
Palpable breast masses with probably benign morphology at sonography: can biopsy be deferred?
Authors: Park Y.-M. , Kim E.-K. , Lee J.-H. , Ryu J.-H. , Han S.-S. , Choi S.-J. , Lee S.-J. , Yoon H.-K. 
Published: October 2008

Background: When a palpable breast mass is detected, a biopsy is usually performed even if the mass reveals probably benign morphologic features on imaging, as there is relatively little data reporting the outcome of such breast masses. Purpose: To determine the negative predictive value for sonographic evaluation of palpable breast masses with probably benign morphology, and to assess whether follow-up may be an acceptable alternative to immediate biopsy. Material and Methods: Of the 1399 sonograms of palpable masses from January 2004 to September 2005, there were 397 patients with masses of probably benign morphology. This study included 274 of these patients (age range 12–64 years, mean age 34 years) with 312 palpable masses that were pathologically confirmed by fine-needle aspiration ( n=7), ultrasound (US)-guided core needle biopsy ( n=180), or surgical biopsy ( n=125). The false-negative rate, negative predictive value (NPV), and 95% confidence interval (CI) were calculated using the SPSS statistical software package for Windows, version 12.0. A P value <0.05 was considered statistically significant. Results: Of the 312 masses, there were 310 benign lesions and two malignancies, resulting in a false-negative rate of 0.6% (NPV 99.4%, P value=0.0432, 95% CI 0.0–1.5%). Conclusion: The negative predictive value of sonography for palpable breast masses with probably benign morphology is high (99.4%). Therefore, short-term imaging follow-up can be an acceptable alternative to immediate biopsy, similar to the management of nonpalpable probably benign lesions (BI-RADS category 3).
Voxel-based correlation between coregistered single-photon emission computed tomography and dynamic susceptibility contrast magnetic resonance imaging in subjects with suspected alzheimer disease
Authors: Cavallin L. , Axelsson R. , Wahlund L. O. , Öksengard A. R. , Svensson L. , Juhlin P. , Wiberg M. Kristoffersen , Frank A. 
Published: October 2008

Background: Current diagnosis of Alzheimer disease is made by clinical, neuropsychologic, and neuroimaging assessments. Neuroimaging techniques such as magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT) could be valuable in the differential diagnosis of Alzheimer disease, as well as in assessing prognosis. Purpose: To compare SPECT and MRI in a cohort of patients examined for suspected dementia, including patients with no objective cognitive impairment (control group), mild cognitive impairment (MCI), and Alzheimer disease (AD). Material and Methods: 24 patients, eight with AD, 10 with MCI, and six controls, were investigated with SPECT using 99mTc-hexamethylpropyleneamine oxime (HMPAO, Ceretec; GE Healthcare Ltd., Little Chalsont UK) and dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) with a contrast-enhancing gadobutrol formula (Gadovist; Bayer Schering Pharma, Berlin, Germany). Voxel-based correlation between coregistered SPECT and DSC-MR images was calculated. Region-of-interest (ROI) analyses were then performed in 24 different brain areas using brain registration and analysis of SPECT studies (BRASS; Nuclear Diagnostics AB, Stockholm, Sweden) on both SPECT and DSC-MRI. Results: Voxel-based correlation between coregistered SPECT and DSC-MR showed a high correlation, with a mean correlation coefficient of 0.94. ROI analyses of 24 regions showed significant differences between the control group and AD patients in 10 regions using SPECT and five regions in DSC-MR. Conclusion: SPECT remains superior to DSC-MRI in differentiating normal from pathological perfusion, and DSC-MRI could not replace SPECT in the diagnosis of patients with Alzheimer disease.
mspire: mass spectrometry proteomics in Ruby
Authors: Prince John T. , Marcotte Edward M. 
Published: October 2008

Abstract
Summary: Mass spectrometry-based proteomics stands to gain from additional analysis of its data, but its large, complex datasets make demands on speed and memory usage requiring special consideration from scripting languages. The software library ‘mspire’—developed in the Ruby programming language—offers quick and memory-efficient readers for standard xml proteomics formats, converters for intermediate file types in typical proteomics spectral-identification work flows (including the Bioworks .srf format), and modules for the calculation of peptide false identification rates.
Availability: Freely available at http://mspire.rubyforge.org. Additional data models, usage information, and methods available at http://bioinformatics.icmb.utexas.edu/mspire
Contact: marcotte@icmb.utexas.edu
First Report of Brown Ring Patch Caused by Waitea circinata var. circinata on Poa trivialis in Florida
Authors: Flor N. , Harmon P. , Datnoff L. , Raid R. , Nagata R. 
Published: October 2008

Brown ring patch is a newly described disease of cool-season turfgrass first reported in Japan on creeping bentgrass (Agrostis palustris) (2) and later reported in California on annual bluegrass (Poa annua) (1). The disease is characterized by either patches or rings of discolored to blighted turfgrass that can range from a few centimeters to a meter in diameter. Affected turfgrass plants turn chlorotic and can be blighted from the crown to the leaf tips. Blight symptoms have been associated with fluffy white-to-cream aerial mycelium after extended incubation of the sample. Symptoms including patches of blighted turfgrass approximately 10 cm in diameter were observed on roughstalk bluegrass (Poa trivialis) that had been overseeded onto a dormant ‘Tifdwarf’ bermudagrass (Cynodon dactylon) putting green in Palatka, FL. A sample was submitted by the superintendent in June 2005 because symptoms were confused with dollar spot and a fungicide resistance issue was suspected. The sample produced abundant aerial mycelium after incubation. The pathogen was isolated on potato dextrose agar amended with rifampicin (100 ppm) and streptomycin (100 ppm) from Poa plants surface disinfested with 70% ethanol for 30 s. Colony and sclerotia morphology were consistent with Waitea circinata var. circinata as previously described (1,2). The teleomorph W. circinata var. circinata was not observed on plant material or culture plates. Amplified fragments of rDNA including internal transcribed spacers from the isolate were sequenced bidirectionally from four bacterial clones. The consensus sequences (GenBank Accession Nos. FJ029103, FJ029104, FJ029105, and FJ029106) matched with 99% homology (99% sequence overlap) isolate TRGC1.1 of W. circinata var. circinata described by Wong, NCBI Accession No. DQ900586 (1). Pots of ‘Cypress’ roughstalk bluegrass that were 1 week postemergence were inoculated with the pathogen using 10 infested wheat grains. Plants were incubated at 25°C in a sealed plastic bag with a moist paper towel in the bottom. Hyphae grew from the grains and colonized the grass. Individual plants began to turn chlorotic within 3 days and greater than 90% of the turf in pots was dead after 1 week. The fungus was reisolated from affected plants. Control pots were inoculated with uninfested wheat grains and showed no disease symptoms after 1 week. Inoculations were repeated twice more with the same results. To our knowledge, this is the first report of brown ring patch on P. trivialis in Florida. References: (1) K. A. de la Cerda et al. Plant Dis. 91:791, 2007. (2) T. Toda et al. Plant Dis. 89:536, 2005.