bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability of autonomous vehicle formations using an ISS small‐gain theorem for networks
Authors: Dashkovskiy Sergey N. , Rüffer Björn S. , Wirth Fabian R. 
Published: February 2009

AbstractWe consider a formation of vehicles moving on the two dimensional plane. The movement of each vehicle is described by a system of ordinary differential equations with inputs. The formation is maintained using autonomous controls that are designed to maintain fixed relative distances and orientations between vehicles. Moreover this formation should track a given trajectory on the plane. The vehicles can measure the relative distances and angles to their neighbors. These values are the inputs from one system to another. With the help of a general ISS small–gain theorem for networks we will show that the dynamics of such a formation is stable for the given controls. The notion of local input–to– state stability (local ISS) will be used for this purpose. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transient resonance problems in the case of the series of short duration loads
Authors: Mironowicz Władysław , Sęk Marcin 
Published: February 2009

AbstractThe indicated in the title of this paper vibration problem concern the ferroconcrete slab – type industrial ceilings. The presence of unilateral constraints which my arise as a result of construction damages is taken into consideration. As an example, it is analysed a construction of a ceiling in shape of a rectangular slab supported on a regular net of columns and a non deformed solid, being a model of a machine, placed on the construction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The influence of parametric excitation on floating bodies
Authors: Zelei A. , Stepan G. 
Published: February 2009

AbstractIn the present study, we investigate the possibility of stabilizing a floating body that is unstable without parametric excitation. We prescribe a non–stationary geometric constraint, that is, the centre of gravity is moved periodically in vertical direction. This periodic movement causes the parametric excitation described by a non–autonomous differential equation. By using the stability chart of the Mathieu equation, we can find sets of parameters where the stabilization of the floating body is realizable. This can help in the stabilization of a canoeist, but it can also cause stable ships to capsize. Numerical simulations and an experiment were also accomplished to confirm that the stability chart derived for the case of the floating body is realistic. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Regularization Parameter Selection in Total Variation Based Image Denoising
Authors: Dong Yiqiu , Hintermüller Michael , Rincon Monserrat 
Published: February 2009

AbstractA new approach of selecting the regularization parameter in a multiscale total variation model is proposed. The method is combined with a primal–dual algorithm to get a new iteration method for noise removal. Numerical results illustrate significant improvement over other popular methods. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Approximation by generalized Shannon sampling operators generated by band‐limited kernels
Authors: Tamberg Gert 
Published: February 2009

AbstractIn this paper we consider some generalized Shannon sampling operators, which are defined by band–limited kernels. In particular, we use dilated an averaged versions of some previously known kernels. We give also some examples of using sampling operators in imaging applications. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of magnetic field on the rheological properties of liquid GaInSn alloy
Authors: Borin Dmitry , Odenbach Stefan , Nikrityuk Petr 
Published: February 2009

AbstractIn this work we studied experimentally the effect of an applied magnetic field and shear rate on the viscosity of a liquid GaInSn alloy. The experimental investigations were performed at room temperature in a homebuilt shear stress controlled rheometer. To consider the magnetohydrodynamical effects occurring in the melt numerical simulation of the flow field in the melt have been made. The results show a remarkable increase of the viscosity with increasing magnetic field strength. With increasing shear rate applied to the liquid GaInSn alloy a reduction of the change of viscosity is found. As first assumption this rheological behavior of GaInSn can be accounted to the presence of solid oxide fractions in the melt. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal control in fluid mechanics by finite elements with symmetric stabilization
Authors: Braack Malte 
Published: February 2009

AbstractWe formulate four properties for a finite element discretization of the Oseen system which are sufficient to derive a quasi–optimal a priori estimate in the context of optimal control problems. In particular, local projection stabilization and edge–oriented stabilization result to be quasi–optimal for optimal control problems with the Oseen system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Measurements of transient flow fields driven by a discontinuously applied rotating magnetic field
Authors: Raebiger D. , Eckert S. , Gerbeth G. 
Published: February 2009

AbstractThis experimental study considers the transient liquid metal flow which is generated inside a cylindrical container by discontinuously applying a rotating magnetic field (RMF). The focus is on the fluid motion arising from the impulsive spin–up from the resting state. The ultrasonic Doppler velocimetry (UDV) has been used to determine profiles of the fluid velocity in the ternary alloy GaInSn. The azimuthal and vertical velocity components have been measured allowing for an analysis of both the primary, swirling flow and the secondary flow in the radial–meridional plane. The experimental results show an excellent agreement with recently published numerical results. The investigations reveal that the recirculating flow in the radial–meridional plane undergoes characteristic oscillations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MHD turbulence in a channel with spanwise field
Authors: Krasnov Dmitry , Zikanov Oleg , Schumacher Joerg , Boeck Thomas 
Published: February 2009

AbstractWe study turbulent channel flow of an electrically conducting liquid with a homogeneous magnetic field imposed in the spanwise direction. The Lorentz force is modelled using the quasistatic approximation. Direct and large–eddy simulations are performed for hydrodynamic Reynolds numbers Re=10000 and Re=20000 and the Hartmann number varying in a wide range. The main effect of the magnetic field is the suppression of turbulent velocity fluctuations and momentum transfer in the wall–normal direction. Comparing the results from direct and large–edddy simulations we show that the dynamic Smagorinsky model accurately reproduces the flow transformation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rectification, mixing, self‐induced oscillations, measurement and control in asymmetrically grooved channels
Authors: Beronov K. N. , Osorio Nesme A. , Fridman I. , Delgado A. 
Published: February 2009

AbstractTwo separate constructions used in advanced microfluidics are combined to achieve controlled mixing and mass transport at maximum efficiency over minimal distance. One is the use of grooves to enhance mixing – an intensively investigated technique employed in electronic components cooling. So far, only grooves of ectangular cross–sections were used. The other construction builds on the well known effect of partial rectification in axially asymmetric channels and has been employed for valvless pumping. It is now shown that a cascade of axially asymmetric grooves retains and even improves the rectification efficiency of a single nozzle while offering the potential of simultaneous mixing enhancement by a factor of more than 2. The latter is achieved in a certain range of moderate Reynolds numbers characterized by self–induced oscillations at much higher frequency than that of flow actuation. Tuning the pressure drop provides precise control of the effective flow rate, up to suppression or reversion. The duration and intensity of mixing and shearing can thus be adjusted within a broad range and effected in very short channels without additional actuators. In the regime of self–induced oscillations, a few identical sensors with sufficient temporal resolution for temperature or concentration allow reliable determination of the flow rate as well as of the admixture composition of the transported fluid. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microcomputed tomography analysis of ferrofluids used as drug carriers for cancer treatment
Authors: Rahn Helene , Odenbach Stefan 
Published: February 2009

AbstractTwo new approaches, Magnetic Drug Targeting (MDT) and Magnetic Hyperthermia, are being investigated in order to reduce side effects generated by common ways of cancer treatment. MDT and MHT are based on the use of magnetic nanoparticles: for MDT the nanoparticles are used as drug carriers and for MHT the nanoparticles are used to induce local heat transfer within the tumour. The success of these therapeutic approaches depends among other things on the correct distribution of the magnetic nanoparticles within the tumour tissue. Computed tomography analysis has been performed on tumour tissue after MDT in order to examine this distribution. The measurements have been performed in two different laboratories, one based on a synchrotron radiation, and another one on a cone X–ray source. First results show that the drug carriers are contained in the vessel system of the tumour as well as concentrated in the surrounding area of the veins. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical investigation of the flow in a stenosis
Authors: Travnikov Vadim , Böhme Gert 
Published: February 2009

AbstractThe theoretical investigation of the flow in stenosis is presented. We use a new formulation of the incompressible Navier–Stokes equation in terms of an auxiliary field that differs from the velocity by a gauge transformation [1]. The gauge freedom allows us to formulate simple boundary conditions for the auxiliary field and the gauge field as well. The gauge field eliminates the pressure distribution in the Navier–Stokes equation. The numerical investigation of the creeping flow, depending on the geometrical parameters of the system, is performed. The influence of the pressure drop has been taken into account. An excellent agreement with the analytical results in frames of the film theory was observed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaptive multiresolution schemes for reaction‐diffusion systems
Authors: Bendahmane Mostafa , Bürger Raimund , Ruiz Ricardo , Schneider Kai 
Published: February 2009

AbstractThis note outlines a fully adaptive multiresolution scheme with local time stepping for the efficient numerical solution of (possibly degenerate) reaction–diffusion systems. A new numerical example showing Turing–type pattern formation is presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Boundary Integral Method for Compressible Stokes Flow
Authors: Köster Daniel 
Published: February 2009

AbstractA recently developed type of biochip employs ultrasonic surface acoustic waves (SAWs) as a microscale pumping and mixing mechanism for fluids. The driving force for fluid flow is an effect of nonlinear acoustics known as acoustic streaming. We recently studied a two–scale numerical model to describe this effect, which was discretized using classical finite element methods.The micro–scale part of the model describes the propagation of damped acoustic waves. Since the used equations are linear and homogeneous, it is natural to look toward a boundary integral method and attempt a coupling with the FEM scheme still employed in the macro–scale model part. One main ingredient for this approach, namely explicit formulas for free–space Green's functions describing damped acoustics, appear to be novel. We will describe some details of the new scheme, which shows a promising gain of efficiency compared to using FEM for damped acoustics. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonequispaced fast Fourier transforms without oversampling
Authors: Kunis Stefan 
Published: February 2009

AbstractRecently, the fast Fourier transform (FFT) has been generalised for arbitrary sampling nodes by the use of approximation schemes. We show that such nonequispaced FFTs can be implemented without oversampling, i.e., no extra memory besides the input and output array is needed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Supply chains in life‐science applications
Authors: Langemann Dirk 
Published: February 2009

AbstractThe systemic investigation of the energy metabolism in the frame of the selfish–brain theory focusses on supply chains from the energy exploration in the remote environment to the energy consumption by neurons in the brain. Modelling this, the main difficulty consists in the selection of significant core models among the enormous number of known substances and regulatory mechanisms, which are afflicted with considerable incertainties in general. We investigate general supply chains and deduce indispensable elements in the regulatory mechanisms from available observations. A critical selection of system properties and underlying mechanisms enables us to simulate observations, which cannot be explained by the classical glucastatic and lipostatic theory. These observations are e.g. the nearly constant energy level in the brain, the different response of the periphery and the brain to atrophic periods and finally, the development of diabetes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parameters Identification as Identification of External Loads
Authors: Menshikov Yu. 
Published: February 2009

AbstractSubstitution of traditional problem of parameters identification to a problem of identification of some additional external load to researched system is offered in conditions, when the initial information on researched parameter and about statistical properties of measurements is absent or is insignificant. Such substitution is always possible as the contribution of any parameter can be considered as the contribution of additional external load in the response of researched system. At the given approach the mistake in a choice of structure of mathematical model with identified parameters does not lead to principle errors of the solution. This additional load compensates all errors. Besides it is possible to carry out check of a hypothesis about a constancy of parameter size.The problem was reduced to solution of the integral equation of the first kind with an inexact kernel and inexact right part. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Robust Error Estimates for Adaptive Phase Field Simulations
Authors: Bartels Sören , Müller Rüdiger 
Published: February 2009

AbstractPhase field equations are commonly used as a regularized model, where bulk phases are separated by interface regions that have a thickness of the order γ. Their numerical analysis is well established for a fixed parameter size γ, but conventional error estimates depend exponentially on γ−1 and thus become useless in the relevant case if γ→0. Technical applications include e.g. the simulation of Sn–Cu alloys for the production of lead free solder or Ni–Al alloys used for rotor blade surfaces. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preconditioned Uzawa Algorithm for Elastic Contact Problems
Authors: Pop Nicolae 
Published: February 2009

AbstractAfter finite element discretization of the elastic contact problems with friction, we obtain a big sparse non–symmetric and nonlinear systems of equations, and in many cases ill–conditioned. Solving these systems by direct methods or classical iterative methods are non efficient and with bad convergence properties. One way to overcome these difficulties is to use the preconditioned Uzawa–type algorithms. On this paper we focus on the transformation of the generalized Signorini elastic contact problems into a saddle point problem of some augmented Lagrangian functional and give a preconditioning technique for Uzawa algorithm. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Regulation von Immunsystem und Allergien. Retinoide, Vitamin A und Pro‐Vitamin‐A‐Carotinoide
Authors: Rühl Ralph 
Published: February 2009

AbstractVitamin A und Pro‐Vitamin‐A‐Carotinoide sind in hohen Konzentrationen in der westlichen Ernährung enthalten. Eine humane Vitamin‐A‐Defizienz kommt in westlichen Ländern daher extrem selten vor. Eine Überversorgung mit Vitamin A tritt jedoch häufig auf und kann möglicherweise ein wesentlicher Faktor bei der gesteigerten Prävalenz von atopischen Erkrankungen in westlichen Ländern sein. Dabei spielt der Einfluss von Vitamin A auf das Immunsystem eine mögliche entscheidende Rolle.Retinsäuren, die haupt‐aktiven Derivate des Vitamin A, sind spezifische und selektive Aktivatoren von nukleären Hormon‐Rezeptoren und sind somit wichtige nahrungsrelevante Metaboliten für das Immunsystem. Die Regulation spezifischer Immunantworten auf Allergien ist in einem großen Maße abhängig von Retinoiden. Konzentrationen von Vitamin A und Pro‐Vitamin‐A‐Carotinoiden in unserer Nahrung, und somit später im Körper, können spezifische Immunfunktionen sowohl positiv als auch negativ beeinflussen.
Zur Sicherheit von Vitaminen. Nebenwirkungen, Kontraindikationen und Intoxikationen
Authors: Golly Ines C. 
Published: February 2009

AbstractIm Rahmen der Prävention und Therapie mit Vitaminpräparaten sind die Heilberufe besonders gefordert, ihre Expertise in die Beratung sowohl von Verbrauchern als auch Patienten einzubringen. Entgegen der weltweit verbreiteten Ansicht vieler Verbraucher, die den Vitaminen nur Positives abgewinnen und diesen Substanzen grundsätzlich unkritisch gegenüberstehen, macht insbesondere die langfristige Einnahme hoher Dosen eine Nutzen‐Risiko‐Abwägung für den einzelnen Verbraucher/Patienten erforderlich.
Vitamine in der Schwangerschaft. Welche Vitaminpräparate empfehle ich der Schwangeren?
Authors: Mayer Sonja 
Published: February 2009

AbstractWissenschaftlich nachgewiesene Wirksamkeit von Folsäure zur Risikoreduktion von Neuralrohrdefekten, ein eklatanter Mehrbedarf von z.B. 58 % Pyridoxin und 50 % Folsäure sowie ein Mangel an diesen B‐Vitaminen, Vitamin A und Vitamin D sprechen eindeutig für die Supplementierung in der Schwangerschaft. Aufgrund teratogener Effekte ist bei Vitamin A und Vitamin D auf Höchstdosen zu achten.
Vitamine zwischen Mangelvermeidung und Prävention. Wunsch und Wirklichkeit
Authors: Hahn Andreas 
Published: February 2009

AbstractAus ernährungswissenschaftlicher Sicht besitzt eine adäquate Vitaminversorgung nicht nur die Aufgabe, Mangelerscheinungen zu vermeiden, sondern trägt auch dazu bei, chronisch‐degenerativen Erkrankungen vorzubeugen. Auf Bevölkerungsebene ergibt sich in Deutschland im Mittel rechnerisch mit Ausnahme von Folsäure und Vitamin D eine insgesamt ausreichende Zufuhrsituation. Allerdings ist erkennbar, dass auch bei anderen Vitaminen in einem teilweise erheblichen Teil der Bevölkerung nicht die wünschenswerte Aufnahme erreicht wird. Zwar sind schwerwiegende Vitaminmangelerscheinungen dabei sehr selten zu finden, bisweilen treten aber latente Defizite auf, die sich in unspezifischen Symptomen äußern können. Nach der derzeitigen Studienlage kann eine optimierte Vitaminversorgung zur Prävention verschiedener Erkrankungen beitragen. Interventionsstudien konnten deshalb vor allem dann eine entsprechende Wirkung von Vitaminsupplementen zeigen, wenn die Studienteilnehmer zuvor schlecht versorgt waren. Ob und in welchem Umfang zusätzliche Vitamingaben bei bereits guter Vitaminversorgung von Nutzen sind, bleibt nach wie vor offen.
Neue Antibiotika in Sicht?
Authors: Holzgrabe Ulrike 
Published: February 2009

AbstractIn den letzten 40 Jahren wurden nur zwei neue Antibiotikagruppen aufgefunden, und zwar die Oxazolidinone (Linezolid) und die Lipopeptide (Daptomycin), die neue Zielstrukturen bedienen, um ihre bakerizide Wirkung zu entfalten. Übrigens wurden beide Gruppen – wie auch die wenigen anderen Substanzen in der Pipeline wie Glycolipodepsipeptide (Ramoplanin), Pleuromutiline (Retapamulin) oder Glycosyltransferase‐Inhibitoren (Moenomycin) – schon vor sehr langer Zeit aufgefunden, aber damals aus verschiedenerlei Gründen wie z.B. Toxizität nicht weiterentwickelt.
Red red wine
Authors: Bajer M. , Bezbradica S. , Buzek F. , Renz H. , Schröder K. , Song M. , Zündorf I. , Dingermann T. 
Published: February 2009

AbstractVielleicht kann – wie Neil Diamond einst meinte – Rotwein über eine verlorene Liebe hinweg helfen; pharmazeutisch interessanter ist, ob wirklich Rotwein und hier vor allem das Resveratrol für das “French Paradoxon” verantwortlich ist. Demnach schützen sich die Franzosen trotz vielen Tabakonsums und cholesterinreicher Ernährung mit Rotwein vor Herzinfarkten.
PCR/LDR/capillary electrophoresis for detection of single‐nucleotide differences between fetal and maternal DNA in maternal plasma
Authors: Yi Ping , Chen Zhuqin , Zhao Yan , Guo Jianxin , Fu Huabin , Zhou Yuanguo , Yu Lili , Li Li 
Published: February 2009

AbstractBackgroundThe discovery of fetal DNA in maternal plasma has opened up an approach for noninvasive diagnosis. We have now assessed the possibility of detecting single‐nucleotide differences between fetal and maternal DNA in maternal plasma by polymerase chain reaction (PCR)/ligase detection reaction((LDR)/capillary electrophoresis.MethodsPCR/LDR/capillary electrophoresis was applied to detect the genotype of c.454–397T>gene (ESR1) from experimental DNA models of maternal plasma at different sensitivity levels and 13 maternal plasma samples.αC in estrogen receptor.Results(1) Our results demonstrated that the technique could discriminate low abundance single‐nucleotide mutation with a mutant/normal allele ratio up to 1:10 000. (2) Examination of ESR1 c.454–397T>C genotypes by using the method of restriction fragment length analysis was performed in 25 pregnant women, of whom 13 pregnant women had homozygous genotypes. The c.454–397T>C genotypes of paternally inherited fetal DNA in maternal plasma of these 13 women were detected by PCR/LDR/capillary electrophoresis, which were accordant with the results of umbilical cord blood.ConclusionsPCR/LDR/capillary electrophoresis has very high sensitivity to distinguish low abundance single nucleotide differences and can discriminate point mutations and single‐nucleotide polymorphisms(SNPs) of paternally inherited fetal DNA in maternal plasma. Copyright © 2009 John Wiley & Sons, Ltd.
Should the first‐trimester aneuploidy screen be maternal age adjusted? Screening by absolute risk versus risk adjusted to maternal age
Authors: Gebb Juliana , Dar Pe'er 
Published: February 2009

AbstractObjectiveTo compare the absolute risk (AR) screening approach to the current approach of risk adjusted to maternal age in patients undergoing first‐trimester screening (FTS).Material and MethodsThree‐stage retrospective analysis of 3073 pregnancies that had FTS during 2006–2007. (1) Distribution analysis of AR as defined by (final FTS risk)/(risk by age). (2) Analysis of the screen‐positive group by the AR method. (3) Analysis of the screen‐positive advanced maternal age (AMA) patients.Results(1) AR > 1 was found in 151 (4.9%) patients, and AR > 1.2, 2 and 3 was found in 4, 3.1 and 2%, respectively. (2) 145 (4.7%) of the 3073 patients screened positive. Twelve were diagnosed with chromosomal abnormalities and 3 with major anomalies. All had AR > 1.2. Of the 145 (55.8%) screen positives, 81 had AR > 1.2. AR was significantly higher in the chromosomally abnormal as compared to normal gestations (t‐test, p < 0.01). (3)Of the 145 screen positives, 103 were AMA. Only 39 (28%) had an AR > 1.2.ConclusionsThe AR screening approach, using AR > 1.2 as a cut‐off, captured all abnormal pregnancies diagnosed by the current screening method. This method offers lower false positive (FP) rates to AMA women and has the potential for higher detection rates in younger women. Copyright © 2009 John Wiley & Sons, Ltd.