bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of Copolymer Bottle‐Brushes
Authors: Hsu Hsiao‐Ping , Paul Wolfgang , Binder Kurt 
Published: June 2007

AbstractSummary:The structure of bottle‐brush polymers with a rigid backbone and flexible side chains is studied in three dimensions, varying the grafting density, the side chain length, and the solvent quality. Some preliminary results of theoretical scaling considerations for one‐component bottle‐brush polymers in a good solvent are compared with Monte Carlo simulations of a simple lattice model. For the simulations a variant of the pruned‐enriched Rosenbluth method (PERM) allowing for simultaneous growth of all side chains in the Monte Carlo sampling is employed. For a symmetrical binary (A,B) bottle‐brush polymer, where two types (A,B) of flexible side chains are grafted with one chain end to the backbone in an alternating way, varying repulsive binary interactions between unlike monomers and the solvent quality, it is found that phase separation into anA‐rich part of the cylindrical molecule and aB‐rich part can occur only locally. Long range order (in the direction of the backbone) does not occur, and hence the transition from the randomly mixed state of the bottle‐brush to the phase‐separated structure is strongly rounded, in contrast to the corresponding mean field predictions of a sharp transition to a “Janus cylinder” phase‐separated structure. This lack of a phase transition can be understood from an analogy with spin models in one dimension. By estimating the correlation length for this phase separation along the backbone as a function of side chain length and solvent quality, we present strong evidence that no sharp phase transition occurs.
Molecular Dynamic Simulation of Side‐Chain Liquid Crystalline Elastomer Under Load
Authors: Darinskii Anatoly A. , Zarembo Anna , Balabaev Nikolai K. 
Published: June 2007

AbstractSummary:We present a molecular dynamic simulation of a side chain liquid crystalline elastomer (LCE) under load. The LCE is composed of a flexible tetrafunctional diamond like network with rod‐like mesogens attached to the network. As a precursor of the LC elastomer a flexible polymer network in a low molecular liquid‐crystal (LC) solvent was used. The phase behavior of the LCE under uniaxial stretching up to the deformations ofλ = 1.5 and 2.0 at different densities was studied. As in the non‐stretched case upon density increase an isotropic to nematic phase transition occurs. However, in contrast to thermotropic side chain LC elastomers the stress induced shift transition is not observed. The stretching slightly increases the anisotropy of translational diffusion of mesogens in the nematic state. The stress‐strain dependence for LCE both in the isotropic and the nematic states is obtained. Elastic modulus increases at high values of order parameter.
Charged Semi‐Permeable Shell with Encapsulated Polyions: Concentration Profile, Surface Potential, and Electrostatic Pressure
Authors: Tsekov Roumen , Vinogradova Olga I. 
Published: June 2007

AbstractSummary: We study theoretically the electrostatic equilibrium for a charged shell filled with a suspension of polyions (e.g., colloids, polyelectrolytes, etc.) and immersed in an infinite salt‐free reservoir. The shell is impermeable for polyions, but allows free diffusion of counterions. From the solution of the linearized Poisson‐Boltzmann equation we obtain the distribution of the potential and concentration profiles for polyions. We then derive explicit formulas for the electrostatic pressure exerted by the shell. If the overall charge of the filled shell has the same sign as the surface alone the pressure on the shell increases with increase of the surface charge density. Otherwise the surface charge density suppresses the electro‐osmotic pressure due to the electrostatic attraction between the oppositely charged polyions and shell.
Polyamine‐mediated regulation of protein acetylation in murine skin and tumors
Authors: Wei Gang , Hobbs Cheryl A. , DeFeo Karen , Hayes Candace S. , Gilmour Susan K. 
Published: June 2007

AbstractOverexpression of ornithine decarboxylase (ODC), resulting in increased polyamine metabolism, is a common feature of epithelial tumors. Polyamines play a complex role in promoting tumor development, affecting diverse cellular processes, including gene expression. One way polyamines may affect gene expression is to modulate the multiprotein complexes comprised of transcription factors and coregulatory factors that alter chromatin structure by acetylating/deacetylating nearby histones. We have capitalized on ODC‐overexpressing cultured cells and K6/ODC and ODC/Ras transgenic mouse models, in which ODC overexpression is targeted to hair follicles, to evaluate the influence of polyamines on the acetylation of histones and other proteins. ODC overexpression was found to alter intrinsic histone acetyltransferase (HAT) and deacetylase activities and histone acetylation patterns. The high HAT activity exhibited by ODC transgenic mouse skin and tumors might be partly attributed to enhanced p300/creb‐binding protein (CBP)‐associated HAT activity and increased levels of Tat interactive protein, 60 kDa (Tip60) HAT protein isoforms. Altered association of Tip60 with E2F1 and a subset of newly identified Tip60‐interacting transcription factors was detected in ODC mouse skin and tumors, implying novel polyamine modulation of Tip60‐regulated gene expression. Polyamine effects on HAT enzymes also influence the acetylation status of nonhistone proteins. Overexpression of ODC in skin serves as a novel stimulus for acetylation of the tumor suppressor protein, p53—a target of both p300/CBP and Tip60—with concomitant increased binding to, and increased transcription of, a downstream target gene. The future challenge will be to elucidate the multiple mechanisms by which polyamines influence enzymes that regulate protein acetylation and gene transcription to promote cancer. © 2007 Wiley‐Liss, Inc.
Explicit solutions of the one‐dimensional Vlasov–Poisson system with infinite mass
Authors: Pankavich Stephen 
Published: June 2007

AbstractA collisionless plasma is modelled by the Vlasov–Poisson system in one dimension. A fixed background of positive charge, dependent only upon velocity, is assumed and the situation in which the mobile negative ions balance the positive charge as |x| → ∞ is considered. Thus, the total positive charge and the total negative charge are infinite. In this paper, the charge density of the system is shown to be compactly supported. More importantly, both the electric field and the number density are determined explicitly for large values of |x|. Copyright © 2007 John Wiley & Sons, Ltd.
Riccati equation‐based generalization of Dawson's integral function
Authors: Messina R. , Jivulescu M. A. , Messina A. , Napoli A. 
Published: June 2007

AbstractA new generalization of Dawson's integral function based on the link between a Riccati nonlinear differential equation and a second‐order ordinary differential equation is reported. The MacLaurin expansion of this generalized function is built up and to this end an explicit formula for a generic cofactor of a triangular matrix is deduced. Copyright © 2007 John Wiley & Sons, Ltd.
Quantitative analysis of mitochondrial RNA in goat–sheep cloned embryos
Authors: Ma Li‐Bing , Yang Li , Zhang Yong , Cao Jun‐Wei , Hua Song , Li Ji‐Xia 
Published: June 2007

AbstractMitochondria are the key generators of cellular ATP, and contain extranuclear genome‐mitochondrial DNA (mtDNA). In the process of nuclear transfer (NT), heteroplasmic sources of mtDNA from a donor cell and a recipient oocyte are mixed in the cytoplasm of the reconstituted embryo. Previous studies showed inconsistent patterns of mtDNA inheritance in offspring and early fetuses generated through interspecies NT. The quantitative analysis of mitochondrial RNA (mtRNA) in interspecies cloned embryos is useful for better understanding the fate of two types of mitochondria. The components of nicotinamide adenine dinucleotide (NADH) dehydrogenase were coded by both nuclear DNA (nDNA) and mtDNA. The Subunit 1 (ND‐1) is one of seven NADH dehydrogenase subunits coded by mtDNA. In present study, using real‐time and reverse‐transcription PCR, the copy number of species‐specific ND‐1 mRNA was examined in goat–sheep cloned embryos of various developmental stages, and was applied to evaluate the expression pattern of species‐specific mtDNA. The results of showed that (1) the expression of mtDNA derived from goat fetal fibroblast (GFF) decreased from 1‐cell stage (immediately after fused) to 2‐cell stage, and could not be detected from 4‐cell stage onward to blastocyst stage; (2) the expression of mtDNA derived from sheep oocyte was roughly constant from 1‐cell stage to the 8‐cell stage, increased gradually from 16‐cell stage, and sharply at morula and blastocyst stage. Moreover, we strongly argued a mechanism, that is GFF‐derived mitochondria were degraded for the depression of bioenergetic functions, and then selectively eliminated during the embryogenesis of goat‐sheep cloned embryos. Mol. Reprod. Dev. 75: 33–39, 2008. © 2007 Wiley‐Liss, Inc.
Bifurcation and instability modelling by a multimechanism elasto‐plastic model
Authors: Hamadi Kamel , Modaressi‐Farahmand Razavi Arézou , Darve Félix 
Published: June 2007

AbstractThe bifurcation and instability conditions in geomechanics are closely related to the elasto‐plastic behaviour. In this paper the potential of a multimechanism elasto‐plastic model to predict various modes of failure is examined. First, a brief overview for the essential aspects of the constitutive model and the development of the elasto‐plastic constitutive matrix for this model are presented. Then, numerical simulations of different drained and undrained paths in the axisymmetric and plane‐strain conditions for the Hostun sand are illustrated. These examples confirm the capacity of the model to reproduce instability and strain localization phenomena. The
obtained response is in agreement with experimental observations, theoretical developments and numerical analyses existing in the literature. Copyright © 2007 John Wiley & Sons, Ltd.
The impact of manufacturer rebates on supply chain profits
Authors: Chen Xin , Li Chung‐Lun , Rhee Byong‐Duk , Simchi‐Levi David 
Published: June 2007

AbstractManufacturer rebates are commonly used as price discount tools for attracting end customers. In this study, we consider a two‐stage supply chain with a manufacturer and a retailer, where a single seasonal product faces uncertain and price‐sensitive demand. We characterize the impact of a manufacturer rebate on the expected profits of both the manufacturer and the retailer. We show that unless all of the customers claim the rebate, the rebate always benefits the manufacturer. Our results thus imply that “mail‐in rebates,” where some customers end up not claiming the rebate, particularly when the size of the rebate is relatively small, always benefit the manufacturer. On the other hand, an “instant rebate,” such as the one offered in the automotive industry where every customer redeems the rebate on the spot when he/she purchases a car, does not necessarily benefit the manufacturer. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007
In vivo MRI using positive‐contrast techniques in detection of cells labeled with superparamagnetic iron oxide nanoparticles
Authors: Liu Wei , Dahnke Hannes , Jordan E. Kay , Schaeffter Tobias , Frank Joseph A. 
Published: June 2007

AbstractPositive‐contrast techniques are being developed to increase the detection of magnetically labeled cells in tissues. We evaluated a post‐processing positive‐contrast technique, susceptibility‐gradient mapping (SGM), and compared this approach with two pulse sequences, a gradient‐compensation‐based “White Marker” technique and an off‐resonance‐based approach, inversion recovery on‐resonance water suppression (IRON), for the detection of superparamagnetic iron oxide (SPIO) nanoparticle‐labeled C6 glioma cells implanted in the flanks of nude rats. The SGM, White Marker and IRON positive‐contrast images were acquired when the labeled C6 glioma tumors were ∼5 mm (small), ∼10 mm (medium) and ∼20 mm (large) in diameter along the largest dimension to evaluate their sensitivity to the dilution of the SPIO nanoparticles as the tumor cells proliferated. In vivo MRI demonstrated that all three positive‐contrast techniques can produce hyperintensities in areas around the labeled flank tumors against a dark background. The number of positive voxels detected around small and medium tumors was significantly greater with the SGM technique than with the White Marker and IRON techniques. For large tumors, the SGM resulted in a similar number of positive voxels to the White Marker technique, and the IRON approach failed to generate positive‐contrast images with a 200 Hz suppression band. This study also reveals that hemorrhage appears as hyperintensities on positive‐contrast images and may interfere with the detection of SPIO‐labeled cells. Published in 2007 by John Wiley & Sons, Ltd.
Robust capacity expansion of network flows
Authors: Ordóñez Fernando , Zhao Jiamin 
Published: June 2007

AbstractWe consider the problem of expanding arc capacities in a network subject to demand and travel time uncertainty. We propose a robust optimization approach to obtain capacity expansion solutions that are insensitive to this uncertainty. Our results show that, under reasonable assumptions for network flow applications, such robust solutions can be computed by solving tractable conic linear problems. For example, the robust solution for a multicommodity flow problem is obtained by solving a linear program if the problem has a single source and sink per commodity and the uncertainty in demand and travel time is given by independent bounded polyhedral sets. Preliminary computational results show that the robust solution is attractive, as it can reduce the worst case cost by more than 20%, while incurring a 5% loss in optimality when compared to the optimal solution of a representative scenario. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(2), 136–145 2007
On stochastic programs over trees with partially dependent arc capacities
Authors: Shi Ning , Cheung Raymond K. , Song Haiqing 
Published: June 2007

AbstractWe study the new problem of stochastic programs over trees with dependent random arc capacities. This problem can be used as a subproblem in decomposition methods that solve multi‐stage networks with independent random arc capacities and random travel times. An efficient algorithm is provided to compute the expected total cost. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(2), 157–163 2007
Multiterminal resilience for series‐parallel networks
Authors: Farley Toni R. , Colbourn Charles J. 
Published: June 2007

AbstractNetwork resilience measures the average two‐terminal reliability (connectedness) of a network. Multiterminal resilience extends this measure to any k vertices; it is the average k‐terminal reliability of a network. This generalizes two well‐studied network connectedness measures. Calculating multiterminal resilience on general networks encompasses all‐terminal reliability and thus is NP‐hard. Multiterminal resilience is examined on undirected series‐parallel networks, and an efficient (polynomial time) algorithm is developed for calculating the resilience for every k. Applications in mobile ad hoc and sensor networks are outlined. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(2), 164–172 2007
Matching preclusion for some interconnection networks
Authors: Cheng Eddie , Lipták László 
Published: June 2007

AbstractThe matching preclusion number of a graph is the minimum number of edges whose deletion results in a graph that has neither perfect matchings nor almost‐perfect matchings. In this paper, we find this number for various classes of interconnection networks and classify all the optimal solutions. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(2), 173–180 2007
A highly accurate collocation Trefftz method for solving the Laplace equation in the doubly connected domains
Authors: Liu Chein‐Shan 
Published: June 2007

AbstractA highly accurate new solver is developed to deal with the Dirichlet problems for the 2D Laplace equation in the doubly connected domains. We introduce two circular artificial boundaries determined uniquely by the physical problem domain, and derive a Dirichlet to Dirichlet mapping on these two circles, which are exact boundary conditions described by the first kind Fredholm integral equations. As a direct result, we obtain a modified Trefftz method equipped with two characteristic length factors, ensuring that the new solver is stable because the condition number can be greatly reduced. Then, the collocation method is used to derive a linear equations system to determine the unknown coefficients. The new method possesses several advantages: mesh‐free, singularity‐free, non‐illposedness, semi‐analyticity of solution, efficiency, accuracy, and stability. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
A family of conservative finite difference schemes for the dynamical von Karman plate equations
Authors: Bilbao Stefan 
Published: June 2007

AbstractNumerical methods for nonlinear plate dynamics play an important role across many disciplines. In this article, the focus is on numerical stability for numerical methods for the von Karman system, through the use of energy‐conserving methods. It is shown that one may take advantage of structure particular to the system to construct numerical methods, which are provably numerically stable, and for which computer implementation is simplified. Numerical results are presented. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
Approximation and eigenvalue extrapolation of biharmonic eigenvalue problem by nonconforming finite element methods
Authors: Jia Shanghui , Xie Hehu , Yin Xiaobo , Gao Shaoqin 
Published: June 2007

AbstractIn this paper, we analyze the biharmonic eigenvalue problem by two nonconforming finite elements, Q and E Q. We obtain full order convergence rate of the eigenvalue approximations for the biharmonic eigenvalue problem based on asymptotic error expansions for these two nonconforming finite elements. Using the technique of eigenvalue error expansion, the technique of integral identities, and the extrapolation method, we can improve the accuracy of the eigenvalue approximations. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2008
Integration of high‐risk human papillomavirus: a key event in cervical carcinogenesis?
Authors: Pett M , Coleman N 
Published: June 2007

AbstractAn important occurrence in cervical carcinogenesis is deregulated expression of the high‐risk human papillomavirus (HR‐HPV) oncogenes E6 and E7. Several risk factors for cervical neoplastic progression are likely to contribute to viral oncogene deregulation, particularly integration of HR‐HPV into the host genome. Integration represents a by‐product of viral infection that is detected in almost 90% of cervical carcinomas. The mechanism of integration is not fully understood, although there is a clear predilection for chromosomal common fragile sites, most likely due to their accessibility for insertion of foreign DNA. Recent work has suggested that an important intermediate stage in cervical carcinogenesis is characterized by transcriptionally silent HR‐HPV integrants, which co‐exist with viral episomes in infected cells. As episome‐derived E2 protein inhibits integrant transcription, clearance of episomes (eg by host innate immunity) is associated with loss of integrant silencing and integrant selection. The process of integration and subsequent clonal selection of integrants can therefore be considered as two independent and biologically distinct events. Indeed, integrated HPV may be viewed as selectable because it represents a form of the virus that is resistant to host mechanisms of viral clearance, enabling infected cells to maintain viral oncogene expression and avoid cell death. Care should be taken in interpreting studies of HPV integration frequency in clinical samples, as the techniques used have assessed either the presence of integrated viral DNA or evidence of transcriptional activity from integrants, but not both. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Methylation of tumor‐suppressor genes in neuroblastoma: The RASSF1A gene is almost always methylated in primary tumors
Authors: Michalowski Mariana Bohns , de Fraipont Florence , Plantaz Dominique , Michelland Sylvie , Combaret Valérie , Favrot Marie‐Christine 
Published: June 2007

AbstractBackgroundCurrently, the best characterized genetic aberration in neuroblastoma (NB) is MYCN amplification, which has been clearly related to prognosis. In the present study, we investigated whether specific epigenetic alterations are associated with stage of disease.ProcedureSixty‐two NBs (45 primary tumors and 17 NBs at relapse) were studied in terms of the methylation status of 19 genes (p15INK4a, p16INK4a, p14ARF, APC, RB1, RASSF1A, BLU, FHIT, RARβ, INI1, TIMP3, NF2, MGMT, DAPK, FLIP, ECAD, CASP8, and the receptors DcR1 and DcR2).ResultsAt diagnosis, we found hypermethylation of RASSF1A in 93% of these tumors, hypermethylation of TIMP3 in 51%, of CASP8 in 38%, of BLU in 34%, of DcR2 in 25%, and of DcR1 in 11%. All 17 tumors tested at relapse showed hypermethylation of RASSF1A (100%), while 10 showed hypermethylation of TIMP3 (59%), six of CASP8 (35%), five of DcR2 (29%), four of BLU (24%), and three of DcR1 (18%). Hypermethylation was related to clinical stage; NBs at stages 1, 2, and 4s were less frequently methylated than stages 3 and 4 disease (P = 0.002).ConclusionThese results from our series indicate that hypermethylation of tumor‐suppressor genes may be important in the development and evolution of NB. These epigenetic alterations could be used as a marker of the disease and genes regulating methylation should be considered as possible therapeutic targets in NB. Pediatr Blood Cancer 2008;50:29–32. © 2007 Wiley‐Liss, Inc.
Reducing irinotecan‐associated diarrhea in children
Authors: Wagner Lars M. , Crews Kristine R. , Stewart Clinton F. , Rodriguez‐Galindo Carlos , McNall‐Knapp Rene Y. , Albritton Karen , Pappo Alberto S. , Furman Wayne L. 
Published: June 2007

AbstractIrinotecan is increasingly being used in pediatric oncology. Amelioration of diarrhea associated with protracted irinotecan administration may reduce morbidity and improve dose intensity. In this review, we discuss what is known about the pathogenesis of this toxicity as well as potential predisposing genetic factors. We comprehensively summarize the literature regarding available prevention and treatment strategies, and report data on the use of cephalosporin prophylaxis in 51 patients treated on various pediatric trials. This approach is feasible in children and allows for tolerance of higher doses of protracted irinotecan. Pediatr Blood Cancer 2008; 50:201–207. © 2007 Wiley‐Liss, Inc.