bluuebunny/crossref_metadata_2025_split huggingface dataset:
Free‐surface instabilities during electromagnetic shaping of liquid metals
Authors: Karcher Ch. , Kocourek V. 
Published: October 2008

AbstractElectromagnetic shaping of free surfaces of liquid metals is a well‐known EPM technology used in a couple of metallurgic processes like cold crucible melting, semi‐levitation, and electromagnetic slit sealing, among others. However, the stability of such free surfaces is the most important problem and stability control is crucial for success. Within this context we investigate experimentally the stability behavior of liquid metal free surfaces submitted to a high‐frequency magnetic field. In this case, the induced Lorentz forces act as an electromagnetic pressure directly on the free surface of the liquid met al. We consider three experimental model configurations: (i) Sessile liquid metal drop (ii) liquid metal ring, and (iii) liquid metal disc. In each model experiment, upon increasing the feeding current beyond a certain threshold value, IC, we observe that the initial surface contour becomes unstable resulting in (i) drop oscillations (ii) electromagnetic pinching and (iii) static disc deformations. In each configuration the threshold value depends in a similar manner on the frequency of the applied magnetic field. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A min‐max version of Dijkstra's algorithm with application to perturbed optimal control problems
Authors: Lossow Marcus von 
Published: October 2008

AbstractIn this paper the computational complexity of a newly developed min‐max version of Dijkstra's algorithm for solving the shortest path problem in a directed weighted hypergraph is analyzed. Together with a set oriented discretization of the state space this algorithm provides a new numerical approach for the construction of an optimally stabilizing feedback under perturbations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Blackmann‐Harris windows for Shannon sampling series
Authors: Tamberg Gert 
Published: October 2008

AbstractThis paper deals with some approximations by the generalized Shannon sampling series, which are defined by the Blackman‐Harris (or cosine‐sum) window functions. In the case of certain (m+ 1)‐term cosine‐sum window functions the order of approximation can be estimated via the 2m‐th modulus of continuity. Some choices of parameters in Blackman‐Harris window function generate interpolating generalized Shannon sampling series. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Conjugate gradient algorithms for best rank‐1 approximation of tensors
Authors: Curtef O. , Dirr G. , Helmke U. 
Published: October 2008

AbstractMotivated by considerations of pure state entanglement in quantum information, we consider the problem of finding the best rank‐1 approximation to an arbitrary r ‐th order tensor. Reformulating the problem as an optimization problem on the Lie group SU (n1) ⊗ … ⊗ SU (nr) of so‐called local unitary transformations and exploiting its intrinsic geometry yields a new approach, which finally leads to Riemannian variant of the conjugate gradient algorithm. Numerical simulations support that our method offers an alternative to the higher‐order power method for computing the best rank‐1 approximation to a tensor. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantized vortices in BEC and superconductors
Authors: Du Qiang 
Published: October 2008

AbstractQuantized vortices is a well‐know signature of superfluidity. They have been studied extensively in superfluid Helium, type‐II superconductors, Bose Einstein condensates and more recently in Fermi gas. We will discuss some mathematical analysis and numerical simulations of the quantized vortex nucleations in superconductors and Bose‐Einstein condensates and discuss their connections and similarities. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Convergence to equilibrium for some nonlinear evolution equations with dynamical boundary condition
Authors: Wu Hao 
Published: October 2008

AbstractIn this short note we present some convergence results of solutions to certain equilibrium for some nonlinear evolution equations subject to dynamical boundary condition by using the Łojasiewicz‐Simon approach. The work was done in collaboration with S. Zheng and M. Grasselli. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sacrococcygeal teratoma over two decades: Birth prevalence, prenatal diagnosis and clinical outcomes
Authors: Swamy Ravi , Embleton Nicholas , Hale Juliet 
Published: October 2008

AbstractObjectiveThe birth prevalence and malignant tumour recurrence of sacrococcygeal teratoma (SCT) have not been clearly defined. We conducted this study to determine the birth prevalence, prenatal detection rate, frequency of tumour recurrence and outcome of SCT in a population‐based cohort.MethodsCases were identified from a population‐based, regional database of congenital anomalies for the years 1985–2006. Prenatal diagnosis, management details, tumour recurrence and outcome were obtained from case records and cross linked with a regional oncology database.ResultsThere were 754 172 live births and 28 live born infants with SCT giving a birth prevalence of 1 per 27 000 live births. There was a prenatal diagnosis in 50% of cases. No cases presenting in the neonatal period had malignant tumour present at diagnosis or subsequent tumour recurrence. Nine (37.5%) of the survivors had chronic morbidities.ConclusionsThe birth prevalence of SCT was higher than that of previously reported. Infants who were live born and survived definitive surgical management had a good prognosis. Copyright © 2008 John Wiley & Sons, Ltd.
The presence of trophoblastic cells in intrauterine lavage samples: lack of correlation with maternal and obstetric characteristics
Authors: Cioni Riccardo , Bussani Cecilia , Conti Elisa , Buzzoni Carlotta , Bucciantini Sandra , Mattei Alberto , Scarselli Gianfranco 
Published: October 2008

AbstractObjectivesTo investigate the correlation between maternal, obstetric and sample characteristics and the quality (i.e. yield of trophoblastic cells) of intrauterine lavage (IUL) samples.MethodsWe collected 202 IUL samples from women scheduled for first trimester termination of pregnancy (TOP). Trophoblastic cells were isolated from IUL samples and used for DNA analysis by a multiplex quantitative fluorescent polymerase chain reaction (QF‐PCR) assay. A multivariate logistic regression analysis was performed, and a p < 0.05 was considered statistically significant.ResultsThe presence of trophoblastic cells in IUL samples was documented in 151/202 cases (74.7%). Blood contamination of IULs was the only characteristic to positively correlate with the presence of trophoblasts (p = 0.039; OR: 1.99; 95% CI: 1.03–3.82).ConclusionsThe correlation between the presence of contaminating blood and trophoblastic cells would indirectly confirm the hypothesis that IUL might act as a mini‐CVS. The high yield rate of trophoblasts irrespective of maternal characteristics and past obstetric history would support the clinical use of this sampling technique, provided that its safety is clearly defined. Copyright © 2008 John Wiley & Sons, Ltd.
Hundert Jahre Mie‐Theorie. Optische Eigenschaften von Nanopartikeln
Authors: Kreibig Uwe 
Published: October 2008

Abstract1908 veröffentlichte Gustav Mie eine Arbeit mit dem Titel “Beiträge zur Optik trüber Medien, speziell kolloidaler Metalllösungen” in den Annalen der Physik. Heute ist sie als Mie‐Theorie berühmt. Auf Basis der Maxwell‐Theorie beschreibt sie exakt die Wechselwirkung zwischen einer ebenen elektromagnetischen Welle und einem beliebigen kugelförmigen Körper, auf den sie trifft. Sie ist auf Wassertröpfchen in der Atmosphäre ebenso anwendbar wie auf Nanopartikel. In modifizierter Form hat sie vor allem für die Nanowissenschaften eine grundlegende Bedeutung. In Gustav Mies Lebenswerk stellt sie als angewandte Arbeit einen Sonderfall dar. Er suchte nach einer Feldtheorie, die Elektromagnetismus mit Materie vereinigt, scheiterte aber daran.
Eine höchst liebenswerte Philosophin
Authors: Loos Andreas 
Published: October 2008

AbstractViel ist über ihre Kindheit nicht zu erfahren. So gilt sie als einziges Kind eines Rechtsanwalts, das das Säuglingsalter überlebt. Das erklärt wohl die besondere Fürsorge in Ausbildungsfragen, die dem Mädchen zuteil wird. Schon bald erweist es sich als Wunderkind, das in kurzer Zeit Latein lernt.
Zuckerwasser statt Öl: süßes “Frittieren”
Authors: Vilgis Thomas 
Published: October 2008

AbstractFrittiert wird meist in Öl, aber muss das sein? Frittierfette haben of einen schlechten Ruf, und die Suche nach Alternativen nimmt kein Ende. Wie schön wäre es, mit schlichtem Wasser zu frittieren. Das hätte keine Kalorien, und viele Vorbehalte träten erst gar nicht auf. Aber Wasser siedet unter Normaldruck bei 100 °C – zu niedrig zum Frittieren. Durch Zuckerzugabe lässt sich der Siedepunkt deutlich erhöhen. Aber reicht dies zum Frittieren?
Sample size effects on the transport characteristics of mesoscopic graphite samples
Authors: Barzola‐Quiquia J. , Yao J.‐L. , Rödiger P. , Schindler K. , Esquinazi P. 
Published: October 2008

AbstractIn this work we investigated correlations between the internal microstructure and sample size (lateral as well as thickness) of mesoscopic, tens of nanometer thick graphite (multigraphene) samples and the temperature (T) and field (B) dependence of their electrical resistivity ρ (T, B). Low energy transmission electron microscopy reveals that the original highly oriented pyrolytic graphite material – from which the multigraphene samples were obtained by exfoliation – is composed of a stack of ∼50 nm thick and micrometer long crystalline regions separated by interfaces running parallel to the graphene planes. We found a qualitative and quantitative change in the behavior of ρ (T, B) upon thickness of the multigraphene samples, indicating that their internal microstructure is important. The overall results indicate that the metallic‐like behavior of ρ (T) at zero field measured for bulk graphite samples is not intrinsic of ideal graphite. The results suggest that the interfaces between crystalline regions may be responsible for the superconducting‐like properties observed in graphite. Our transport measurements also show that reducing the sample lateral size as well as the length between voltage electrodes decreases the magnetoresistance, in agreement with recently published results. The magnetoresistance of the multigraphene samples shows a scaling of the form [(R (B) – R (0))/R (0)]/Tα = f (B /T) with a sample dependent exponent α ∼ 1, which applies in the whole temperature 2 K ≤ T ≤ 270 K and magnetic field range B ≤ 8 T. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical resistivity and photoluminescence of zinc oxide films prepared by ultrasonic spray pyrolysis
Authors: Bouzid Khedidja , Djelloul Abdelkader , Bouzid Noureddine , Bougdira Jamal 
Published: October 2008

AbstractZinc oxide (ZnO) thin films have been prepared by ultrasonic Spray pyrolysis (USP) technique using zinc acetate dihydrate dissolved in methanol, ethanol and deionized water. A number of techniques, including X‐ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, UV–visible, electrical resistivity, and photoluminescence (PL) were used to characterize the obtained ZnO thin films. The evolution of the preferred crystalline orientations in the ZnO films was systematically investigated. The PL measurements indicated that the as‐grown ZnO thin films showed UV and green emission bands when they were excited by a Hg arc lamp using 313 nm as the excitation source. A red‐shift in the near band edge (NBE) has been observed with the increase in the substrate temperature and has been attributed to the compressive intrinsic stress present in the films. It is confirmed that oxygen vacancy (VO) is the most important factor that causes the broad visible emission. Furthermore, the visible emission and electrical resistivity of ZnO thin films are found to be a function of porosity. Also, it has been interestingly found that the intensity of green emission at ∼2.5 eV remarkably increased when the obtained ZnO films were deposited at 320 °C. The reason might be the VO, intrinsic stress, surface‐to‐volume ratio and porosity in the sample increased at low substrate temperature. The resistivity follows the same behavior as the intensity of the green emission. We propose a new luminescence mechanism based on the recombination related to oxygen vacancies in Zn‐rich or stoichiometric conditions. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Error propagation in multiscale approaches to the elasticity of polycrystals
Authors: Friák Martin , Counts William Art , Raabe Dierk , Neugebauer Jörg 
Published: October 2008

AbstractThe error propagation properties of the Voigt, Reuss, Voigt–Reuss–Hill–Gilvarry, and Hershey schemes for the determination of the integral elastic response of texture free polycrystalline aggregates with cubic structure were studied. The sensitivity of the homogenized polycrystalline shear modulus was tested (i) analytically on the partial derivatives of the shear modulus with respect to the individual elastic constants within extremal Voigt and Reuss schemes, and (ii) numerically for all four methods. The sensitivity of the Hershey shear modulus on the input parameters, the single crystalline elastic constants B, C ′, C44, is shown to be within the limiting values found for the Voigt and Reuss schemes. This conclusion is illustrated numerically on a set of five cubic materials with very different physical properties. The influence of the bulk modulus was found to be approximately two orders of magnitude smaller than that of C ′ and C44. The Hershey modulus was also found to be non‐linear, asymmetric, and strongly dependent on the level of the elastic anisotropy of the studied system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Relation between the topology of the elementary energy bands in the valence band of the Hg3TeCl4 crystal and its anisotropy
Authors: Sznajder M. 
Published: October 2008

AbstractA mechanism of the Davydov‐like splitting formation in the Brillouin zone of the Hg3TeCl4 crystal (Pbca, D2h15) with two double translationally nonequivalent layers in the unit cell was analyzed. The topology of the 8‐branch elementary energy bands creating the valence band of Hg3TeCl4 was explained. Energetic distances between states of the elementary energy bands at the Brillouin zone edges were estimated by means of the localized function method. The topology of the elementary energy bands was related with the ratio of the interaction strength between the double layers in the unit cell and the interaction strength between single layers creating the double layer. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Oxygen vacancy configuration of δ‐Bi2O3: an ab initio study
Authors: Zhong Guohua , Wang Yao , Dai Zhenxiang , Wang Jianglong , Zeng Zhi 
Published: October 2008

AbstractThe oxygen vacancy configurations and electronic structures of δ‐Bi2O3 have been studied using the ab initio calculation full‐potential linearized augmented plane‐wave (FPLAPW) method and considering the relativistic effect in Bi atoms in terms of spin–orbital coupling. Three vacancy structures, 〈111〉, 〈110〉 and 〈100〉, were analysed. It was found that the layered δ‐Bi2O3 with 〈110〉 vacancy alignment is the most stable. An indirect band gap of 0.46 eV was observed for this structure. Additionally, the role of lone‐pair electrons as well as polarization during the diffusion of oxygen atoms have been investigated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kinetics of coupled ordering and segregation in antiphase domains
Authors: Gumennyk K. , Stefanovich L. , Feldman E. 
Published: October 2008

AbstractWe study a multi‐domain ordering kinetics in solid solutions under simultaneous diffusion of solute atoms. By the example of a binary bcc alloy a system of kinetic equations is derived, describing the coupled relaxation of occupancies of the two sublattices, building a bcc lattice, by A and B atomic species. Such an approach supplemented by the simplest mean‐field approximation proves sufficient to describe both the establishing of long‐range order and the segregation processes occurring in antiphase domains. An interaction and interrelation between evolution of the conserved and non‐conserved order parameter fields are elucidated. Asymptotical and numerical analysis of the obtained evolution equations reveals a multi‐stage scenario of the alloy relaxation: first comes the quick development of long‐range order which is then followed by the slow redistribution of local alloy concentration, so that the majority atoms segregate towards the region of an antiphase boundary. The alloy exhibits a distinct tendency to form a multi‐domain structure out of a solitary long‐range order parameter fluctuation of a certain sign. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling suppressed and active convection: Comparisons between three global atmospheric models
Authors: Willett M. R. , Bechtold P. , Williamson D. L. , Petch J. C. , Milton S. F. , Woolnough S. J. 
Published: October 2008

AbstractThe Met Office Unified Model, the European Centre for Medium‐Range Weather Forecasts (ECMWF) Integrated Forecasting System and the National Center for Atmospheric Research (NCAR) Community Atmosphere Model 3 were used to compare simulations of suppressed and active convection by global atmospheric models (GAMs) in the Tropical West Pacific. The case used a three‐week period selected from the Tropical Ocean and Global Atmosphere‐Coupled Ocean‐Atmosphere Response Experiment (TOGA‐COARE). The global models were initialized from ERA‐40 on each day of the case and the 12‐36 h forecasts were concatenated together to create a continuous sequence of forecasts. One active and two suppressed subperiods were identified and used to examine the behaviour of the models within different convective regimes. All the GAMs were able to clearly distinguish between the suppressed and active regimes in terms of precipitation rate, precipitable water and radiative fluxes, and they all produced strong deep convection during the most active period. However, there were significant differences in the behaviour of the GAMs convection parametrizations during the most suppressed period. There was good agreement in the long‐wave radiative fluxes where the GAMs were in good agreement in terms of convective activity, but there was less agreement in the short‐wave fluxes, with the biggest differences being in the most active period. Throughout, there were large differences in the relative proportion of convective and large‐scale precipitation produced by the GAMs. By making comparisons with reference data in the form of observations, reanalyses and cloud‐resolving models, several issues that were specific to individual GAMs are identified and discussed. Copyright © 2008 Royal Meteorological Society and Crown Copyright, 2008
The new VarEPS‐monthly forecasting system: A first step towards seamless prediction
Authors: Vitart Frédéric , Buizza Roberto , Alonso Balmaseda Magdalena , Balsamo Gianpaolo , Bidlot Jean‐Raymond , Bonet Axel , Fuentes Manuel , Hofstadler Alfred , Molteni Franco , Palmer Tim N. 
Published: October 2008

AbstractA combined medium‐range and monthly‐forecasting forecasting system is now operational at the European Centre for Medium‐Range Weather Forecasts. Previously, these two systems were run separately. The new combined system provides skillful predictions of small‐scale, severe‐weather events in the early forecast range, accurate large‐scale forecast guidance up to day 15 twice a day, and large‐scale guidance up to day 32 once a week. In addition, the daily medium‐range forecasts starting at 0000 utc are now coupled to an ocean general‐circulation model after day 10 and persisted sea‐surface temperature (SST) anomalies instead of persisted SSTs are applied when the atmospheric model is run in uncoupled mode. Average results indicate that the monthly forecasting scores are slightly higher in the Extratropics with this new combined system. In particular, the new system seems to produce better monthly forecasts for extreme events such as the 2003 heatwave over Europe or the 2007 wet summer over England. However, the monthly forecasting scores in the Tropics are slightly lower than with the previous system, most likely because of the lack of ocean‐atmosphere coupling during the first ten days of the forecasts. This demonstrates that ocean‐atmosphere coupling may be needed in medium‐range forecasting and future plans include coupling the atmosphere to the ocean model from day 0. Average results based on 30 cases indicate that the medium‐range forecasts benefit from the introduction of the ocean‐atmosphere coupling after day 10, most especially the prediction of low‐level temperature in the Tropics. Copyright © 2008 Royal Meteorological Society
Assimilation of Doppler radial winds into a 3D‐Var system: Errors and impact of radial velocities on the variational analysis and model forecasts
Authors: Rihan Fathalla A. , Collier Chris G. , Ballard Susan P. , Swarbrick Sean J. 
Published: October 2008

AbstractA pre‐processing approach to the assimilation of Doppler radar radial wind data into a high resolution Numerical Weather Prediction (NWP) model is described. We discuss the types of errors which might occur in radar radial winds. The construction of simulated high resolution radar data containing such errors is described. Examples of these data are presented and compared with actual radar data from the Chilbolton S‐band radar located in central southern England. A new approach to specifying the radial velocity observation error is proposed based upon the radial gradient of the velocity along the pulse volume. The production of ‘super‐observations’ for input to a 3D‐Var assimilation system is discussed. Impact of the assimilation of Doppler velocities on the 3D‐Var analysis and on the model forecasts, for two case‐studies, are shown. Copyright © 2008 Royal Meteorological Society
Tropical‐cyclone intensification and predictability in a minimal three‐dimensional model
Authors: Shin Seoleun , Smith Roger K. 
Published: October 2008

AbstractWe investigate the amplification and predictability of tropical cyclones in the context of a minimal, three‐dimensional numerical model. In the prototype problem for intensification, starting with a tropical storm strength vortex in a quiescent environment on an f‐plane, the emergent flow in the inner region of the vortex becomes highly asymmetric and dominated by deep convective vortex structures, even though the problem as posed is essentially axisymmetric. The details of the intensification process, including the asymmetric structures that develop, are highly sensitive to small perturbations in the low‐level moisture field at the initial time. This sensitivity is manifest in a significant spread in the intensity of vortices from an ensemble of calculations in which random moisture perturbations are added in the lowest model level. Similar experiments are carried out on a β‐plane and in the case where there is an anticyclonic shear flow at upper levels. The former set shows no significant difference from the f‐plane calculations in the evolution of intensity, but the latter set shows a significantly weaker vortex, contrary to a broadly held hypothesis that upper‐level outflow channels are favourable to intensification. Copyright © 2008 Royal Meteorological Society