bluuebunny/crossref_metadata_2025 huggingface dataset:
On stability problems of the space elevator
Authors: Schwarzbart M. , Steindl A. , Troger H.
Published: December 2008

A long dumb‐bell satellite in the radial configuration represents a simple model of a Space Elevator. The dumb‐bell moves with the angular velocity of the planet, but not relative to it. To calculate the stability of such a relative equilibrium we used the reduced energy‐momentum method. We considered dumb‐bell satellite models with rigid and elastic, but massless, rods. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear convective oscillations in multilayer systems
Authors: Simanovskii Ilya B.
Published: December 2008

The joint action of buoyancy and the thermocapillary effect in two‐ and three‐layer systems, is studied. Two types of boundary conditions, periodic boundary conditions and rigid heat–insulated lateral walls, are considered. In the case of periodic boundary conditions, regimes of traveling waves have been found. In the case of rigid heat‐insulated lateral walls, symmetric and asymmetric standing waves are observed. Transitions between different types of oscillatory motions are studied. The competition between buoyancy and the thermocapillary effect in a three‐layer system may lead to the complex dynamics and different unexpected effects. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Drop deformation under surfactants adsorption
Authors: Stan Ioan‐Raducan , Tomoaia‐Cotisel Maria , Stan Aurelia
Published: December 2008

The movements of free liquid drops, resulting from unbalanced surface tension gradients, in our case the adsorption of a surfactant, constitute important surface phenomena (Marangoni effect). The aim of this paper is to correlate the effect of pressure forces on the drop, with the surface coverage degree, namely with the extent to which the drop surface is covered by the surfactant. Our model shows that for a covered degree less then about 68°, these forces are negative. This means that these forces exerted by the external liquid upon the drop are oriented towards the negative direction of the normal to the drop surface, acting like a hammer. Some numerical data are given. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of a tritrophic food chain model
Authors: Tchuenche Jean M.
Published: December 2008

We consider a tritrophic food chain model in which the classical assumption of the domino effect is supplemented with an adaptive parameter. Dynamical behaviours such as boundedness, existence of periodic orbits, persistence, as well as stability are analyzed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synchronization of nuclear spin generator system using active backstepping design
Authors: Umut Ömür
Published: December 2008

In this letter, an active backstepping design control method is presented for synchronizing two identical nuclear spin generator system with each other. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variational principle and reaction‐diffusion front speeds in random flows
Authors: Nolen James , Xin Jack
Published: December 2008

We summarize recent advances of analyzing Kolmogorov‐Petrovsky‐Piskunov (KPP) fronts in random compressible and incompressible flows. In particular, a long standing open problem of the existence and characterization of the so called turbulent flame speed is resolved for KPP fronts in space‐time random incompressible flows under certain regularity and moment conditions on the flow fields. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A numerical method to approximate the solutions of non‐linear absorption diffusion equations
Authors: Dumitrache Alexandru
Published: December 2008

This paper investigates the motivation for the n‐dimensional absorption‐diffusion equation. First, the one‐dimensional, nonlinear absorption‐diffusion equation was mathematically developed. A numerical method to computationally solve it and diffusion‐free equations were also developed. For the cases tested, the numerical diffusion solutions are always less than the numerical diffusion‐free solutions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theory of fundamental operator‐functions of singular differential operators in Banach spaces and this applications
Authors: Falaleev Mikhail V.
Published: December 2008

In this paper we consider applications of the abstract theory of singular differential equations in Banach spaces to applied problems about processes of transfer of moisture, swelling of metallic beams, processes of filtration of fluids in inhomogeneous mediums, oscillation processes in molecules of DNA, transverse vibration of membrane, theory of viscoelastic and others. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Method for evaluation of movement resistance in scraper pipe conveyors
Authors: Furmanik K. , Pracik M.
Published: December 2008

Rational designing of scraper pipe conveyors requires new approach to evaluation of motion resistance. The results of theoretical and experimental investigations of this resistance and final conclusions have been presented in the paper. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mathematical and physical aspect of the solution of the Cauchy problem for a system of equations describing a nonlocal model of propagation of heat with finite speed
Authors: Gawinecki Jerzy August , Łazuka Jarosław , Rafa Józef
Published: December 2008

In our paper we present a new system of equations describing a nonlocal model of propagation of heat with finite speed in three‐dimensional space. Such a system of equations is described by a system of integral – differential equations. At first using the modiffied Cagniard de Hoop method, we construct the fundamental solution of this system of equations. On the basis of the constructed fundamental solution we obtain the explicite formulate of the solution of the Cauchy problem for this system of equations and applying the method of Sobolev and Biesov spaces, we get Lp – Lq time decay estimate for the solution of the Cauchy problem. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recent results on dislocations dynamics and homogenization
Authors: Forcadel Nicolas , Imbert Cyril , Monneau Régis
Published: December 2008

In this note, we present recent results about the homogenization of systems of particles with two‐body interactions, describing dislocation dynamics. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Existence of best approximant in nonconvex domain
Authors: Nashine Hemant Kumar
Published: December 2008

The present work deals with the establishment of an existence result on best approximation for the nonexpansive noncommuting mappings which is not necessarily linear and as defined on non‐starshaped domain of q‐normed space following Meinardus [7] hypothesis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The special routes in plane graphs
Authors: Panyukova Tatiana
Published: December 2008

Let plane undirected graph G = (V, E) be set of items of all manipulator possible trajectories. The problem is constructing of routes satisfying different restrictions. The restrictions can be classified as local and global. For local restrictions the next edge in a route is defined by the conditions set for current vertex or edge. Otherwise restriction is called global. Examples of local restrictions are straightforward paths; a route in which the next edge is defined by the given cycle order on the set of edges incident the current vertex; a route where some edges should be passed in predefined order. The example of global restriction is problem of constructing the cover with ordered enclosing. The paper presents some ways to formalize restrictions and also information about algorithms for constructing of Eulerian covering for plane graph by the sequence of allowed trails. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the stability of the Ekman boundary layer
Authors: Giga Yoshikazu , Saal Jürgen
Published: December 2008

We present a result on well‐posedness and stability of the Ekman boundary layer problem in the space FM(ℝ2, L2(ℝ+)3), i.e., in the space of L2(ℝ+)3‐valued Fourier transformed finite Radon measures. In particular we obtain stability in the angle velocity of rotation, which is important in the analysis of fast oscillating singular limits. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An application of some high order operator splitting methods to systems of stiff differential equations
Authors: Sánchez‐Bernabe Francisco J. , Salcedo‐Ruz Javier
Published: December 2008

In this work we compare operator splitting methods of high order that are applied to problems with stiff matrices. In order to efficiently solve the resultant subproblems is possible to use implicit Runge‐Kutta methods. We apply an alternative extrapolation technique that works well for the tested problems. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sufficient conditions of the existence forced periodic solutions in the automatic controlled systems with the hysteresis feedback (Poster Presentation)
Authors: Semenov M.E. , Butov A.S. , Gulin A.N. , Tolokonnikov P.V.
Published: December 2008

This article is devoted to Control system with the Hysteresis Nonlinearities. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical stability of the KdV equation with a negative forcing
Authors: Whang Sungim , Choi Jeongwhan
Published: December 2008

The waves at the free surface waves of an incompressible and inviscid fluid in a two dimensional domain with horizontal rigid flat bottom with a small obstruction are considered. A time dependent KdV equation with a negative forcing is derived and studied both theoretically and numerically. The existence of a negative solitary‐wave‐like solution of the equation near the Froude number is proved and the numerical stability of the solution is also studied. The numerical stability of the positive both symmetric and unsymmetric solitary‐wave‐like solutions are also studied. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rayleigh‐Benard convection in a dielectric liquid: time‐periodic body force
Authors: Siddheshwar Pradeep G. , Abraham Annama
Published: December 2008

We discuss the thermal instability in a layer of dielectric fluid when the boundaries of the layer are subjected to small amplitude Time‐periodic body force (TBF). Perturbation solution in powers of the amplitude of the applied temperature field is obtained using the Venezian method (1969) [1]. A linear stability analysis is performed. The results of the study, indicate that TBF or g‐jitter leads to delayed convection Also for large frequencies the effect of TBF disappears.The problem has relevance in many dielectric fluid applications wherein regulation of thermal convection is called for. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Elastic‐plastic states of a rotating inhomogeneously heated strain hardening hollow shaft
Authors: Arslan E. , Eraslan A. N. , Mack3 W.
Published: December 2008

Based on Tresca's yield criterion and the flow rule associated with it, the behaviour of a linearly strain‐hardening elastic‐plastic hollow shaft subject to a positive radial temperature gradient and monotonously increasing angular speed is studied. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic K‐L analysis of coherent structures based on DNS of turbulent Newtonian and viscoelastic flows
Authors: Samanta Gaurab , Oxberry Geoffrey , Beris Antony N. , Handler Robert , Housiadas Kostas
Published: December 2008

Earlier work [1, 2], using Karhunen‐Loeve (K‐L) analysis, demonstrated a dramatic enhancement of the importance of large scale motions with increased viscoelasticity and an equally dramatic decrease in the K‐L dimension of the flow (an order of magnitude) as viscoelasticity increases versus similar Newtonian results. In this work we look into dynamics of viscoelastic turbulent flows by projecting the DNS data in time into a selected set of K‐L modes. The dynamics of the coherent structures embedded in turbulent flows were investigated through calculations of mode auto and cross correlations. This allows for a more systematic examination of the role of large‐scale structures in turbulence and drag reduction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computation of Feynman loop integrals
Authors: de Doncker Elise , Shimizu Yoshimitzu , Fujimoto Junpei , Yuasa Fukuko
Published: December 2008

We address multivariate integration and extrapolation techniques for the computation of Feynman loop integrals. Loop integrals are required for perturbation calculations in high energy physics, as they contribute corrections to the scattering amplitude and the cross section for the collision of elementary particles. We use iterated integration to calculate the multivariate integrals. The combined integration and extrapolation methods aim for an automatic calculation, where little or no analytic manipulation is required before the numeric approximation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A variational free‐Lagrange method for shallow water
Authors: Dixon Matthew F. , Ringler Todd
Published: December 2008

This article presents a variational free‐Lagrange (VFL) method for rotating shallow water. This method was first derived by Augenbaum [2] who discretised Hamilton's action principle with a free‐Lagrange data structure. The novel feature of our approach is to exploit the geometric structure preserved by the VFL method to the effect of conserving energy over long‐time simulations. Numerical results demonstrate this property and motivate the extension of this approach to other variational formulations of climate models. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recent advances in Krylov subspace spectral methods
Authors: Lambers James V.
Published: December 2008

This paper reviews the main properties, and most recent developments, of Krylov subspace spectral (KSS) methods for time‐dependent variable‐coefficient PDE. These methods use techniques developed by Golub and Meurant for approximating elements of functions of matrices by Gaussian quadrature in the spectral domain in order to achieve high‐order accuracy in time and stability characteristic of implicit time‐stepping schemes, even though KSS methods themselves are explicit. In fact, for certain problems, 1‐node KSS methods are unconditionally stable. Furthermore, these methods are equivalent to high‐order operator splittings, thus offering another perspective for further analysis and enhancement. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Lessons from the trenches: A survey of approaches for large‐scale projects
Authors: Miner Robert
Published: December 2008

Technical documents are generally difficult to author, publish and maintain due to the complexity inherent in mathematical notation, diagrams, and tables. This article surveys approaches for addressing these challenges used by large‐scale, Web‐based projects involving ongoing workflows. Such workflows fall into four broad categories: the XML Repository model, the TeX Repository model, the Page Layout model, and exotic models. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A hybrid Langrangian scheme for vehicular traffic flow
Authors: Moutari S. , Rascle M.
Published: December 2008

We introduce a fully discrete hybrid scheme for vehicular traffic flow, combining a microscopic description around obstacles such as traffic lights, toll stations, intersections … and a macroscopic description elsewhere. The presented approach is shown to be theoretically rigorous, numerically reliable, and computationally efficient. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mathematical modelling on harmful algal blooms in the presence of toxic substances
Authors: Pal S.
Published: December 2008

Effect of toxin producing plankton and its control is an intriguing problem in marine plankton ecology. In this paper we have proposed a three‐component model consisting of a non‐toxic phytoplankton (NTP), toxin producing phytoplankton (TPP) and zooplankton (Z), where the growth of zooplankton species reduce due to toxic chemicals released by phytoplankton species. It is observed that the three components persist if the predation rate of zooplankton population on toxic phytoplankton is bounded in certain regions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Additive preconditioning in matrix computations
Authors: Pan V. Y. , Murphy B. , Rosholt R.E. , Ivolgin D. , Qian G. , Taj‐Eddin I. , Tang Y. , Yan X.
Published: December 2008

We combine our novel SVD‐free additive preconditioning with aggregation and other relevant techniques to facilitate the solution of a linear system of equations and other fundamental matrix computations. Our analysis and experiments show the power of our algorithms, guide us in selecting most effective policies of preconditioning and aggregation, and provide some new insights into these and related subjects. Compared to the popular SVD‐based multiplicative preconditioners, our additive preconditioners are generated more readily and for a much larger class of matrices. Furthermore, they better preserve matrix structure and sparseness and have a wider range of applications (e.g., they facilitate the solution of a consistent singular linear system of equations and of the eigen‐problem). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mathematical model for waste minimization of a bleach plant in paper industry
Authors: Singh V.P. , Kumar Vivek , Kumar Deepak
Published: December 2008

In the present investigation a steady‐state mathematical model is developed for a typical four stage CEHH bleaching sequence in Indian Pulp and Paper Industry. Each stage of the sequence is composed of chemical additions and mixing, reaction in a retention tower, and washing. Unit operation models were formulated using mass balances on liquor, fibres, kappa number, chemicals and COD based on the assumption of perfect mixing and quasi steady‐state. The COD is used in this paper as an indication of the amount of effluent coming out from four bleaching stages. In order to validate the model, the simulated results are compared with the literature data; a good agreement is achieved between the simulated results with the literature data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Verified global optimization with GloptLab
Authors: Domes Ferenc , Neumaier Arnold
Published: December 2008

GloptLab is a testing and development platform for solving quadratic constraint satisfaction problems, written in MATLAB.

All applied methods are rigorous, hence it is guaranteed that no feasible point is lost. Some emphasis is given to finding a bounded initial box containing all feasible points, in cases where other complete solvers rely on non‐rigorous heuristics.

The algorithms implemented in GloptLab are used to reduce the search space: scaling, constraint propagation, linear relaxations, strictly convex enclosures, conic methods, and branch and bound. From the method repertoire custom made strategies can be built, with a user friendly graphical interface. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The modelling and dynamic analysis of flow through the aortic valve during the cardiac cycle
Authors: Konderla Piotr , Patralski Krzysztof
Published: December 2008

The object under study is an aortic valve, located in the aortic annulus. The aortic valve leaflet has been assumed to be a three‐dimensional object. The computations were performed using the Ansys Multiphysics system. The result of our analysis takes the form of a model describing the interaction between two domains. The opening of the aortic valve model was obtained by iteration process. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An introduction to pathodynamics from the view of homeostasis and beyond
Authors: Trost Donald C.
Published: December 2008

This presentation discusses how dynamic models and Brownian motion methods can be applied to the analysis of clinical measurements. This approach has the potential to facilitate the understanding of biological systems on a macroscopic scale, much like thermodynamics did for physical chemistry. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A complete classification of bifurcation diagrams of a p ‐Laplacian Dirichlet problem
Authors: Lee Shin‐Yi , Liui Jong‐Yi , Wang Shin‐Hwa , Yei Chiou‐Ping
Published: December 2008

We study the bifurcation diagrams of (classical) positive solutions u with |u |∞ ∈ (0, ∞) of the p ‐Laplacian Dirichlet problem (φp (u ′(x)))′ + λfq (u (x))) = 0, –1 ≤ x ≤ 1, u (–1) = 0 = u (1), where p > 1, φp (y) = |y |p –2 y, (φp (u ′))′ is the one‐dimensional p ‐Laplacian, λ > 0 is a bifurcation parameter, and the nonlinearity fq (u) = |1 – u |q is defined on [0, ∞) with constant q > 0. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication of biodegradable poly(trimethylene carbonate) networks for potential tissue engineering scaffold applications
Authors: Zhang C. , Subramanian H. , Grailer J. J. , Tiwari A. , Pilla S. , Steeber D. A. , Gong S.
Published: December 2008

Biodegradable poly(trimethylene carbonate) (PTMC) networks were prepared by photopolymerization of linear (L)‐ and star (S)‐shaped PTMC macromonomers for potential tissue engineering scaffold applications. The L‐ (Mn, 6400) and S‐shaped (Mn, 5880) PTMC macromonomers were synthesized using 1,4‐butane diol and 2‐ethyl‐ 2‐hydroxyl‐propane‐1,3‐diol co‐initiated ring‐opening polymerization of trimethylene carbonate (TMC) in the presence of stannous octoate and subsequent acrylation with acryloyl chloride. Chemical structures of the PTMC macromonomers and their corresponding networks were characterized by 1H NMR and 13C NMR spectroscopy. The human endothelial cell line, EA.hy926 was used to test the biocompatibility, cell adhesion, and proliferation behavior of both PTMC networks. The PTMC networks made from the S‐shaped macromonomers exhibited superior cell adhesion and proliferation behavior than those made of the linear macromonomers. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis and characterization of polyaniline: nanospheres, nanorods, and nanotubes—catalytic application for sulfoxidation reactions
Authors: Sreedhar B. , Radhika P. , Neelima B. , Hebalkar Neha , Rao M. V. Basaveswara
Published: December 2008

The synthesis of nanostructured polyaniline (PANI) with different morphologies by simple alkali‐guided template‐free method followed by doping them with vanadium has been described. The synthesized polyaniline nanoparticles have been well characterized by various techniques. Further, the catalytic activity of the undoped and doped PANI nanostructures for selective oxidation of sulfides to sulfoxides in water has been studied. It was observed that the special morphology of nanostructures plays an important role in enhancement of catalytic activity. Vanadium‐doped PANI nanotubes and nanorods showed higher activity and selectivity than nanospheres. The catalyst has been reused for five consecutive cycles with consistent activity. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis and characterization of liquid crystalline elastomers bearing fluorinated mesogenic units and crosslinking mesogens
Authors: Meng Fan‐Bao , Chen Hai‐Bin , Liu Dan , Zhang Bao‐Yan , Jia Chao
Published: December 2008

Several new side‐chain liquid crystalline (LC) polysiloxanes and elastomers (IP‐VIP) bearing fluorinated mesogenic units and crosslinking mesogens were synthesized by a one‐step hydrosilylation reaction with poly(methylhydrogeno)siloxane, a fluorine‐containing LC monomer 4′‐undec‐10‐enoyloxy‐biphenyl‐4‐yl 4‐fluoro‐benzoate and a crosslinking LC monomer 4′‐(4‐allyloxy‐benzoxy)‐biphenyl‐4‐yl 4‐allyloxy‐benzoate. The chemical structures and LC properties of the monomers and polymers were characterized by use of various experimental techniques such as FTIR, 1H‐NMR, EA, TGA, DSC, POM and XRD. The effect of crosslinking mesogens on mesomorphic properties of the fluorinated LC polymers was studied as well. The obtained polymers and elastomers were soluble in many solvents such as toluene, tetrahydrofuran, chloroform, and so forth. The temperatures at which 5% weight loss occurred (Td) were greater than 250°C for all the polymers, and the weight of residue near 600°C increased slightly with increase of the crosslinking mesogens in the fluorinated polymer systems. The samples IP, IIP, IIIP and IVP showed both smectic A and nematic phases when they were heated and cooled, but VP and VIP exhibited only a nematic mesophase. The glass transition temperature (Tg) of polymers increased slightly with increase of crosslinking mesogens in the polymer systems, but the mesophase–isotropic phase transition temperature (Ti) and smectic A–nematic mesophase transition temperature (TS‐N) decreased slightly. It suggests that the temperature range of the mesophase became narrow with the increase of crosslinking mesogens for all the fluorinated polymers and elastomers. In XRD curves, the intensity of sharp reflections at low angle decreased with increase of crosslinking mesogens in the fluorinated polymers systems, indicating that the smectic order derived from fluorinated mesogenic units should be destroyed by introduction of more crosslinking mesogens. Copyright © 2008 John Wiley & Sons, Ltd.
Estimating the effect of current, previous and never use of drugs in studies based on prescription registries
Authors: Nielsen Lars Hougaard , Løkkegaard Ellen , Andreasen Anne Helms , Hundrup Yrsa Andersen , Keiding Niels
Published: December 2008

Purpose

Many studies which investigate the effect of drugs categorize the exposure variable into never, current, and previous use of the study drug. When prescription registries are used to make this categorization, the exposure variable possibly gets misclassified since the registries do not carry any information on the time of discontinuation of treatment.

In this study, we investigated the amount of misclassification of exposure (never, current, previous use) to hormone therapy (HT) when the exposure variable was based on prescription data. Furthermore, we evaluated the significance of this misclassification for analysing the risk of breast cancer.

Materials and methods

Prescription data were obtained from Danish Registry of Medicinal Products Statistics and we applied various methods to approximate treatment episodes. We analysed the duration of HT episodes to study the ability to identify discontinuation of therapy from prescription data. Furthermore, we compared to results based on self‐reported duration of HT from the Danish Nurse Cohort.

Finally, we analysed the effect of HT exposure on time to breast cancer for the different prescription based exposure variables as well as for self‐reported HT use.

Results

The results of time to discontinuation varied strongly across the different HT assessments. However, misclassification of HT exposure at baseline was limited and hence analysis of the effect of HT on time to breast cancer showed stability across the different exposure assessments with Hazard Ratios ranging from 1.68 to 1.78 for current use compared to never use.

Conclusions

The findings suggest that it is possible to estimate the effect of never, current and previous use of HT on breast cancer using prescription data. Copyright © 2008 John Wiley & Sons, Ltd.
A SELDI‐TOF MS procedure for the detection, quantitation, and preliminary characterization of low‐molecular‐weight recombinant proteins expressed in transgenic plants
Authors: Badri M. Amine , Rivard Daniel , Coenen Karine , Vaillancourt Louis‐Philippe , Goulet Charles , Michaud Dominique
Published: December 2008

We describe a SELDI‐TOF MS procedure for the rapid detection and quantitation of low‐molecular‐weight recombinant proteins expressed in plants. Transgenic lines of potato (Solanum tuberosum L.) expressing the clinically useful protein bovine aprotinin or the cysteine protease inhibitor corn cystatin II were generated by Agrobacterium tumefaciens‐mediated transformation, and then used as test material for the analyses. Real‐time RT‐PCR amplifications and detection of the recombinant proteins by immunoblotting were first conducted for transformed potato lines accumulating the proteins in different cell compartments. Both proteins were found at varying levels in leaves, depending on their final cellular destination and transgene expression rate. These conclusions drawn from standard immunodetection assays were easily confirmed by SELDI‐TOF MS comparative profiling, after immobilizing the leaf proteins of control and transformed lines on protein biochips for weak cationic exchange. This procedure, carried out in less than 2 h, allows for the rapid comparison of recombinant protein levels in transgenic plant lines. The molecular weight of immobilized proteins can also be determined directly from the MS spectra, thus providing a simple way to assess the structural integrity and homogeneity of recombinant proteins in planta, and to identify the most suitable cellular compartments for their heterologous production.
Dissecting the proteome of pea mature seeds reveals the phenotypic plasticity of seed protein composition
Authors: Bourgeois Michael , Jacquin Françoise , Savois Vincent , Sommerer Nicolas , Labas Valérie , Henry Céline , Burstin Judith
Published: December 2008

Pea (Pisum sativum L.) is the most cultivated European pulse crop and the pea seeds mainly serve as a protein source for monogastric animals. Because the seed protein composition impacts on seed nutritional value, we aimed at identifying the determinants of its variability. This paper presents the first pea mature seed proteome reference map, which includes 156 identified proteins (http://www.inra.fr/legumbase/peaseedmap/). This map provides a fine dissection of the pea seed storage protein composition revealing a large diversity of storage proteins resulting both from gene diversity and post‐translational processing. It gives new insights into the pea storage protein processing (especially 7S globulins) as a possible adaptation towards progressive mobilization of the proteins during germination. The nonstorage seed proteome revealed the presence of proteins involved in seed defense together with proteins preparing germination. The plasticity of the seed proteome was revealed for seeds produced in three successive years of cultivation, and 30% of the spots were affected by environmental variations. This work pinpoints seed proteins most affected by environment, highlighting new targets to stabilize storage protein composition that should be further analyzed.
Two‐dimensional gel‐based approaches for the assessment of N‐Linked and O‐GlcNAc glycosylation in human and simian immunodeficiency viruses
Authors: Graham David R. M. , Mitsak Megan J. , Elliott Steven T. , Chen Dawn , Whelan Stephen A. , Hart Gerald W. , Van Eyk Jennifer E.
Published: December 2008

The glycosylation state of envelope glycoproteins in human and simian immunodeficiency viruses (HIV/SIV) is critical to viral infectivity and tropism, viral protein processing, and in virus evasion of the immune system. Using a rapid fluorescent 2‐D gel‐based method coupled with enzymatic pre‐treatment of virus with PNGase F (Peptide: N‐Glycosidase F) and fluorescent 2‐D gels or 2‐D gel Western blotting, we show significant differences in the glycosylation patterns of two SIV strains widely used in animal models of HIV disease and vaccine studies. We also demonstrate the modification of a host protein important in HIV biology (HLA‐DR) by O‐GlcNAc. Further, this experimental pipeline allows for the identification of the modified protein and the site of N‐linked glycosylation by fluorescent 2‐DE coupled with MS and the qualitative and semi‐quantitative assessment of viral glycosylation. The method is fully compatible with downstream glycomics analysis. This approach will permit correlation of virus glycosylation status with pathological severity and may serve as a rapid screen of viruses from physiological samples for further study by more advanced MS methodology.
Ferro–antiferromagnetic coupling and enhancement of magnetoresistance in La0.7Ca0.3MnO3/LaMnO3 composites
Authors: Zhu Y. D. , Li Xing‐Ao , Liao H. H. , Yang Q.
Published: December 2008

The samples with the nominal composition of (La0.7Ca0.3MnO3)1–x /(LaMnO3)x with x = 0.00, 0.05, 0.15 and 0.25 were fabricated using traditional solid‐state reaction method. The electrical‐magnetic transport behavior and magnetoresistance (MR) were studied for the composites in magnetic fields H = 0.3 T, 3 T. Experimental results show that with the increasing of LaMnO3 (LMO) content x, the metal–insulator (M–I) transition temperature TP shifts to lower temperature and the resistivity increases sharply in zero magnetic field. Meanwhile, a significant enhancement in MR is observed for the composites, especially in the low temperature range (below TP). Specially, the maximum MR at 3 T increased from 35% for the pure La0.7Ca0.3MnO3 (LCMO) to 92% for the sample with x = 0.25. We suggest that such enhancement in MR is attributed to the strong ferro–antiferromagnetic coupling effects in the composite system, which increase the magnetic disorder at the grain surface and boundary, will improve the spin‐polarized tunneling process of the conducting electron between adjacent grains, and thus enhance the MR effect. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the improvement of the anode/organic material interface in organic solar cells by the presence of an ultra‐thin gold layer
Authors: Kouskoussa B. , Morsli M. , Benchouk K. , Louarn G. , Cattin L. , Khelil A. , Bernède J. C.
Published: December 2008

The energy conversion efficiency of organic solar cells based on simple electron donor/electron acceptor heterojunction has been studied as a function of the interface anode/electron donor. The anode is fluorine doped tin oxide film. It is shown that the solar cell efficiency increases when a metal ultra thin layer is introduced between the anode and the electron donor. Experimental and theoretical studies show that the work function value of the metal is one of the main factors which allow improving the organic solar cells performances, via better hole collection efficiency. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dielectric relaxation in lead‐free perovskite Ba(Bi1/2Nb1/2)O3
Authors: Prasad K. , Bhagat S. , Nath K. Amar , Choudhary S. N. , Yadav K. L.
Published: December 2008

A new lead‐free perovskite ceramic Ba(Bi1/2Nb1/2)O3 was prepared by a conventional ceramic technique at 1185 °C in oxygen atmosphere. X‐ray diffraction analysis of the compound indicated the formation of a single‐phase monoclinic structure. Dielectric study revealed a diffuse phase transition at 340 °C. Cole–Cole analyses suggested the dielectric relaxation to be of non‐Debye type. Electric modulus studies supported the hopping type of conduction in Ba(Bi1/2Nb1/2)O3. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN‐based vertical cavities with crack‐free high‐reflectivity patterned AlGaN/GaN distributed Bragg reflectors
Authors: Ni X. , Shimada R. , Kang T. D. , Leach J. H. , Özgür Ü. , Morkoç H.
Published: December 2008

We report on GaN‐based vertical cavities using crack‐free 40.5 pair of AlGaN/GaN distributed Bragg reflectors (DBRs) by employing a selective growth method to avoid wafer cracking that has been commonly observed in conventional planar Al(Ga)N/GaN DBRs. An Al0.46Ga0.54N/GaN DBR with ∼98% reflectivity was selectively grown with square patterns of up to 150 × 150 μm2 in size, which were separated from each other by 10 μm wide SiO2 mask stripes. Vertical cavity structures employing InGaN multiple quantum wells were grown on these crack‐free DBRs and capped with 8 pair dielectric SiO2/SiNx DBRs. Cavity mode centered at ∼400 nm was observed to have a quality factor of ∼100. The selective DBR and vertical cavity growth to eliminate crack formation appears very promising for the fabrication of nitride‐based vertical‐cavity surface emitting laser devices. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spatial features control of self‐organised tungsten nanowire arrays
Authors: Milenkovic Srdjan , Hassel Achim Walter
Published: December 2008

Self‐organised tungsten nanowire arrays were produced by a recently established templateless method. Control of spatial features such as diameter and spacing of nanowires was successfully achieved by changing the growth rate during directional solidification. An increase in the growth rate from 1.4 μm s–1 to 55.5 μm s–1 led to a decrease in the nanowire diameter from 560 to 290 nm and the spacing from 3.5 μm to 1.7 μm. The scaling laws of the variation in nanowire diameter and spacing with growth rate are quantitatively determined. Distribution of both, the diameter and the spacing around the average value were quite narrow. Potential applications of such self‐organised W nanowire arrays in nanotechnology are discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular dynamics simulation of annihilation of 60° dislocations in Si crystals
Authors: Meng Qingyuan , Wang Qingsheng
Published: December 2008

The annihilation of two 60° shuffle dislocations is studied via the molecular dynamics method. The Stillinger–Weber (SW) potential and environment‐dependent interatomic potential (EDIP) are used to describe the atomic interactions. The simulation results show that the complete annihilation of the 60° dislocations takes place only when the two dislocations lie on the same slip plane. The annihilation process may occur without external shear stress when the temperature is higher than a critical value. It is found that the critical temperature increases exponentially as a function of distance between the two dislocations. Also revealed in this simulation is an incomplete annihilation occurring when the distance between the slip planes of the two dislocations is less than about 1 nm. If the distance between the two slip planes is larger than about 1 nm, the dislocations will glide on their own slip planes as if no interaction exists between them. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coherence properties and dynamical photon correlations of quantum‐dot‐based microcavity lasers
Authors: Wiersig J. , Gies C. , Jahnke F.
Published: December 2008

Microcavity lasers have attracted considerable attention due to their potential for ultralow threshold lasing. An important parameter to characterize lasers is the spontaneous emission factor β, defined as the ratio of the spontaneous emission into the laser mode to the total spontaneous emission. When β approaches unity in devices with hight cavity quality and low mode volume, the input‐output curve cannot be used to determine the laser threshold unambiguously. To describe the emission properties of microcavity lasers, we investigate the first‐ and second‐order photon correlation functions. Even in the case of β = 1 we find a strong increase of the coherence time and indications of a gradual transition from Bose–Einstein to Poisson statistics. We also study the decay of first‐ and second‐order photon correlations. The detailed characterization of microcavity lasers is particularly important for potential applications in quantum information technologies. Our results are obtained from a microscopic theory for quantum‐dot emitters as active material. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of single quantum dot emission characteristics and fine structure by lateral electric fields
Authors: Ulrich S. M. , Hafenbrak R. , Vogel M. M. , Wang L. , Rastelli A. , Schmidt O. G. , Michler P.
Published: December 2008

The spontaneous emission characteristics of individual self‐assembled (In,Ga)As/GaAs quantum dots have been investigated under the application of a tunable electric field in the lateral growth plane. For the neutral excitonic and bi‐excitonic as well as a singly‐charged (trionic) QD carrier configuration, similar quantum‐confined Stark effects could be observed, thus enabling a direct and comparative determination of corresponding polarizability values α. In addition we have applied a refined detection technique of high‐resolution Fabry–Pérot interferometry on single QDs to investigate the anisotropy‐induced excitonic fine structure and to monitor its tunability under a lateral electric field. Whereas most quantum dots reveal an oscillatory‐type modulation and partial reduction in fine structure under the applied field, we also demonstrate the case of a selected QD where the initial fine structure could even be reversibly tuned down to zero. This fine structure tunability of single QDs represents an essential prerequisite for the realization of individually controlled entangled photon sources in the future. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic properties and phase transitions in Si, ZnSe, and GaAs under pressure cycling up to 20–30 GPa in a high‐pressure cell
Authors: Ovsyannikov Sergey V. , Shchennikov Vladimir V. , Misiuk Andrzej , Komarovsky Ivan A.
Published: December 2008

An automated high‐pressure setup employing anvil‐type cells is applied for investigation of phase transitions and elec‐ tronic properties (the thermoelectric power (Seebeck effect), the electrical resistivity) of silicon, zinc selenide and gal lium arsenide under pressure cycling within the range of 0–20(30) GPa. The “correlation” dependencies of a pressure value of the semiconductor–metal transition in Czochralski‐grown silicon (Cz‐Si) on the concentrations of both carriers and residual interstitial oxygen are discussed. In all Si samples a decompression of the high‐pressure metal phase produces the semimetal p‐type phases: the rhombohedral r8 (Si‐XII) and the body‐centred cubic bc8 (Si‐III) lattices. Re‐ pressurization cycles reveal two features in the semimetal phase, near 2 GPa and 5 GPa. The transitions into the metal phase at higher pressure resemble those in pristine silicon. For ZnSe and GaAs, it is found that decompression from the high‐pressure phases (NaCl and Cmcm, respectively) can follow different paths, producing the zincblende, the cinnabar and the wurtzite lattices. Advantages of the characterization method are discussed, in comparison with both the traditional techniques (X‐ray diffraction, Raman spectroscropy, etc.) and the more recent ones (such as nanoindentation). (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polarized Raman study of self‐assembled Ge/Si dots under hydrostatic pressure
Authors: Reparaz J. S. , Bernardi A. , Goñi A. R. , Alonso M. I. , Garriga M.
Published: December 2008

We have studied the correlation between the morphology of Si‐capped Ge islands grown on Si substrates and their vibrational properties as measured by Raman scattering at ambient and under high hydrostatic pressure. For this study we have grown by molecular beam epitaxy a sample that exhibits a size distribution with two distinct island types having different aspect ratios called pyramids and domes. In accordance, Raman spectra show a double‐peak structure at the frequencies of the Ge–Ge vibrational mode (∼300 cm–1) as well as for the Si–Ge mode (around 400 cm–1). Pairwise, different selection rules have been found for these modes depending upon the Raman polarization configurations, suggesting a correlation between both Ge dot sizes and the double peak structure in the Raman spectra. Finally, a different strain status of the dots was observed by studying the pressure coefficient of the Ge–Ge phonon mode, resulting in a value of 3.3 and 3.6 cm–1/GPa for pyramids and domes, respectively. The main conclusion of our work is that the double‐peak structure observed in Raman spectra is indicative of a bimodal dot size distribution in contrast with what is proposed in previous work within the so‐called core‐shell model [M. Y. Valakh et al., Nanotechnol. 16, 1464 (2005)]. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study of the electronic properties of GaAs‐based atomic layer doped field effect transistor (ALD‐FET) under the influence of hydrostatic pressure
Authors: Martínez‐Orozco J. C. , Rodríguez‐Vargas I. , Duque C. A. , Mora‐Ramos M. E. , Gaggero‐Sager L. M.
Published: December 2008

Based on a Thomas–Fermi envelope function scheme we perform the calculation of the electronic structure of a GaAs atomic layer doped field effect transistors (ALD‐FET). We calculate the electronic structure for the device as a function of the involved parameters, in particular we study the effects of the hydrostatic pressure onto the electronic level structure in order to investigate the formation of high conductivity electron channels in such devices. We consider the pressure‐induced Γ–X crossover within the conduction band as a possible effect causing the enhancement of the associated two‐dimensional carrier densities. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scheme for coherently quenching resonant current in a three‐level quantum dot energy level mixer
Authors: Austing D. G. , Payette C. , Nair S. V. , Yu G. , Gupta J. A. , Partoens B. , Amaha S. , Tarucha S.
Published: December 2008

We outline a scheme to create a “dark” state by three‐level mixing that is potentially a useful tool for quantum coherent transport. Magnetic‐field‐induced intra‐dot level mixing can lead to rich quantum superposition phenomena between three approaching single‐particle states in a quantum dot when probed by the ground state of an adjacent weakly coupled quantum dot in the single‐electron resonant tunnelling regime. The mixing relies on non‐negligible anharmonicity and anisotropy in confining potentials of realistic quantum dots. Anti‐crossing and transfer of strengths between resonances can be understood with a simple coherent level mixing model. Superposition can lead to the formation of a dark state by complete cancellation of an otherwise strong resonance. This is an all‐electrical analogue of coherent population trapping seen in three‐level‐systems from quantum and atom optics. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On dot and out of dot electrical characteristics of silicon oxide nanodots patterned by scanning probe lithography
Authors: Hutagalung Sabar D. , Darsono Teguh
Published: December 2008

Silicon oxide nanodot arrays were grown on pre‐cleaned silicon (100) substrate by scanning probe nanolithography. In this study, a conductive AFM was used to fabricate nanoscale oxide dots in humidity controlled environment. The AFM is equipped with a nanotechnology software package providing the control of tip‐sample voltage and tip motion according to pre‐designed patterns. The surface topography and size of obtained patterns (diameter and height) were investigated by a noncontact AFM mode. A series of five silicon oxide nanodot array with diameter in the range of 146.05‐247.65 nm and height 2.14‐4.87 nm had been successfully fabricated. Meanwhile, a contact AFM mode was used to investigate the localized I‐V characteristics on the dots and out of dot position. It was found, the on dot characteristics are highly nonohmic due to potential barrier interface between silicon oxide and silicon substrate. However, the out of dot characteristic is linear indicates an ohmic contact between AFM tip and sample. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Towards a single‐photon all‐optical transistor
Authors: Dawes Andrew M. C.
Published: December 2008

The Expert Opinion is written by a distinguished scientist and presents his personal view on important and relevant new results of research, highlighting their significance and putting the work into perspective for a broader audience. Please send comments to pss.rapid@wiley‐vch.de or to the author. The text by Andrew M. C. Dawes refers to the Rapid Research Letter by S. Schumacher et al., published in this issue of Phys. Status Solidi RRL 3, 10 (2009). (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)