bluuebunny/crossref_metadata_2025 huggingface dataset:
Unbiased ensemble square root filters
Authors: Dance S. L. , Livings D. M. , Nichols N. K.
Published: October 2008

Ensemble square root filters are a method of data assimilation, where model forecasts are combined with observations to produce an improved state estimate, or analysis. There are a number of different algorithms in the literature and it is not clear which of these is the best for any given application. This work shows that in some implementations there can be a systematic bias in the analysis ensemble mean and consequently an accompanying shortfall in the spread of the analysis ensemble as expressed by the ensemble covariance matrix. We have established a set of necessary and sufficient conditions for the scheme to be unbiased. While these conditions are not a cure‐all and cannot deal with independent sources of bias such as model and observation errors, they should be useful to designers of ensemble square root filters in the future. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On coupled problems in geomechanics
Authors: Ehlers Wolfgang , Graf Tobias , Acartürk Ayhan
Published: October 2008

Geomechanical problems are generally based on the category of granular, cohesive‐frictional materials with a fluid pore content. At the macroscopic scale of continuum mechanics, these materials can be successfully described on the basis of the well‐founded Theory of Porous Media (TPM) [1].

The present contribution touches fundamental problems of coupled media by investigating the interacting behaviour of an elasto‐viscoplastic porous solid skeleton, the soil, and two pore fluids, water and air. Furthermore, electro‐chemical reactions are considered in order to include the swelling behaviour of active soil. In conclusion, this leads to a system of strongly coupled partial differential equations (PDE) that can be solved by use of the finite element method (FEM). In particular, the presentation includes fluid‐flow situations in the fully or the partially saturated range, swelling phenomena of active clay [3] as well as localisation phenomena [2] as a result of fluid flow or heavy rainfall events. The computations are carried out by use of the single‐processor FE tool PANDAS [4] and, in case of large 3‐d problems, by coupling PANDAS with the multi‐processor solver M++. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On necessary conditions for state constrained problems
Authors: Pinho M. d. R. de , Ferreira M. M. A. , Fontes F. A. C. C.
Published: October 2008

Necessary conditions of optimality in the form of Unmaximized Inclusions (UI) were derived for optimal control problems with pathwise state inequality constraints. An approach similar to that used to derive such type of necessary conditions can be followed to obtain relaxation of hypotheses previously imposed on the regularity of the state constraint function. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the interaction of geometry, analysis and stochastics on a body
Authors: Freiberg Uta R.
Published: October 2008

It is reasonable to expect that the geometrical feature of a body has influence to spectral asymptotics of its “natural” Laplacian as well as to the behavior of its “natural” Brownian motion. In fact, such an interaction can be expressed by a so–called “Einstein relation” implicating Hausdorff, spectral and walk dimension. These quantities express geometric, analytic and stochastic aspects of a set. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An interval arithmetic scheme for analyzing uncertain systems
Authors: Gaull Andreas , Kreuzer Edwin
Published: October 2008

This contribution is dedicated to the numerical study of the global behavior of dynamical systems whose mathematical descriptions are imperfect due to uncertainties concerning involved parameters. At the beginning, we constitute themathematical model in order to provide a tailor‐made framework dealing with this problem. Here, uncertainties are regarded as external random noise or perturbations influencing an underlying deterministic system. Afterwards, an interval arithmetic scheme is presented which allows the numerical evaluation of the model. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear iterative operator splitting methods and applications for nonlinear differential equations
Authors: Geiser Jürgen
Published: October 2008

In this paper we discuss decomposition methods that are used for solving nonlinear differential equations. The motivation arose from the need to decouple nonlinear operator equations into simpler, computable operator equations [1]; [2]. We consider iterative operator‐splitting methods for the decoupling of the differential equations and we apply iterative steps to achieve linearisation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Material force method within the framework of the X‐FEM‐distribution of nodal material forces
Authors: Glaser J. , Steinmann P.
Published: October 2008

The Material Force Method (MFM) and the Extended Finite Element Method (X‐FEM), both have been major subjects of computational fracture mechanics in recent time. Thus combining the advantages of both concepts [1, 2] seems a promising approach to describe the behaviour of discontinuities such as cracks in otherwise continuous bodies. As the X‐FEM models a crack independently of the mesh, the crack tip is in general not located at a node which is why a central question is, which nodal material forces do contribute to the resulting material force vector at the crack tip. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Uncertainty quantification for chaotic fluid dynamics
Authors: Glimm James , Jin Hyeonseong
Published: October 2008

We study mesh convergence issues for a representative chaotic flow problem. Convergence in the sense of pointwise convergence fails as new structures emerge with each new level of mesh refinement. We formulate convergence in terms of statistical averages. Care is made to divide the problem into homogeneous regions, and statistical convergence is found for each such region. Automated feature extraction is the tool used for this decomposition.

We study of averaged equations, and the closure problem which arises in their derivation. The accuracy of the closure terms is discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micromechanical modeling of twinning
Authors: Glüge R. , Böhlke T.
Published: October 2008

There exist material models that incorporate mechanical twinning in a homogenized sense, or consider specific aspects, like grain refinement or texture evolution. However, since the RVE‐technique became a standard method, it is possible to obtain more detailed predictions based on micromechanical models. In this work, an approach based on a nonconvex elastic potential and the corresponding results of FE calculations are presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finite thermo‐viscoplasticity of amorphous glassy polymers: Experiments, modeling and simulations
Authors: Göktepe Serdar , Méndez Joel , Miehe Christian
Published: October 2008

The contribution is concerned with experimental procedures, constitutive modeling and the numerical simulations of finite thermo‐viscoplastic behavior of glassy polymers. The experimental study involves both homogeneous and inhomogeneous tests at different temperatures under isothermal conditions. The true stress‐true strain curves obtained from compressive homogeneous uniaxial and plane strain experiments are employed in the identification of adjustable material parameters. In contrast to the existing kinematic approaches to finite plasticity of glassy polymers, we propose a distinct kinematic framework constructed in the logarithmic strain space. This leads us to an algorithmically very attractive, additive kinematic structure in R6 similar to the geometrically linear theory. The proposed three‐dimensional model is implemented into a finite element code. The load‐displacement curves acquired from inhomogeneous experiments are compared against the results obtained from finite element analyses where the material parameters identified from homogeneous experiments are used. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal control for supply network models: Mixed integer programming
Authors: Göttlich Simone , Herty Michael
Published: October 2008

The aim of our investigations is the optimization of a continuous model for a special class of supply networks. We focus on the underlying fundamentals and show the relation to mixed‐integer programming. This is done by applying numerical discretization schemes to the dynamics of the continuous equations and by approximations to the cost functional. One benefit of the MIP model is the adaptivity to real‐world situations by adding reasonable extensions such as bounded queues. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Slant Newton method for elastoplastic problems with linear hardening and its local super‐linear convergence
Authors: Gruber Peter G. , Valdman Jan
Published: October 2008

Elastoplastic problems frequently arise in the science of structural mechanics. Such problems are nonlinear and time dependent, but if one assumes an already discrete model with respect to time, the task is to efficiently solve a one time step problem. In this article we present a solution algorithm for a one time step problem and discuss its super‐linear convergence rate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stochastic binding of Ca2+ ions in the dyadic cleft; continuous vs random walk description of diffusion
Authors: Hake Johan , Lines Glenn Terje
Published: October 2008

Ca2+ signaling in the dyadic cleft in ventricular myocytes is fundamentally discrete and stochastic. In this paper we study the stochastic binding of single Ca2+ ions to receptors in the cleft using two different models of diffusion; a stochastic and discrete Random walk (RW) model, and a deterministic continuous model. We investigate if the latter model, together with a stochastic receptor model, can reproduce binding events registered in fully stochastic RW simulations. By evaluating the continuous model goodness‐of‐fit, we present evidences that it can. The large fluctuations in binding rate observed at the time level of single time steps are integrated and smoothed at the larger time scale of binding events, explaining the continuous model goodness‐of‐fit. With this we demonstrate that the stochasticity and discreteness of the Ca2+ signaling in the dyadic cleft, determined by single binding events, can be described with a deterministic model of Ca2+ diffusion together with a stochastic model of the binding events. Time consuming RW simulations can thus be avoided. We also present a new analytical model of bi‐molecular binding probabilities that is used in the RW simulations, and in the statistical analysis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling and computation of metal powder compaction processes
Authors: Hartmann Stefan , Bier Wolfgang
Published: October 2008

In this short communication the numerical treatment of a thermomechanical consistent finite strain viscoplasticity model for metal powder compaction is discussed. The convex single surface yield function evolves according to two evolution equations and remains convex under all loading conditions. The very challenging numerical treatment on local level for integrating the constitutive model requires particular globally convergent Newton‐like method with inequality constraints so that a stable solution scheme results. This is embedded into a time‐adaptive finite element program which makes use of diagonally‐implicit Runge‐Kutta methods combined with a Multilevel‐Newton algorithm. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two‐scale simulation of damage in unidirectionally fibre reinforced composite materials
Authors: Koester B. , Matzenmiller A.
Published: October 2008

The finite element analysis of engineering structures usually assumes a homogeneous as well as a continuous medium. The heterogeneity of matter, which is always found on a sufficiently small length scale is neglected by replacing the inhomogeneous medium through a model of a mathematically homogenized material. The macroscopic constitutive behaviour is derived from volume averaging procedures that smear the microscopic heterogeneities. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Signal propagation through dense granular systems
Authors: Kondic L. , Behringer R. P.
Published: October 2008

The exact manner in which signals propagate through dense granular systems is still open for discussion. In this work, we present the results of discrete element simulations of the system response to space and time dependent perturbations. Fourier analysis of the system response shows that the properties of the propagating signal strongly depend on the spatial scales introduced by the perturbation itself. The presented results are expected to serve as a basis for development of a continuum model that will describe propagation of signals through dense granular systems. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the non‐linear contact stiffness on the vibration behaviour of a tyre tread block
Authors: Kröger M. , Moldenhauer P. , Gäbel G.
Published: October 2008

The dynamic behaviour of a tyre tread block is described by a modularly arranged model. Special emphasis is laid on the influence of the force‐displacement characteristic between rubber and the rough surface. In the simulation the rough surface on which the tread block slides is modelled as smooth with the friction characteristic of the respective material pairing and a non‐linear description of the local tyre/road interaction. This leads to an adequate description of the contact partners without losing numerical efficiency. Furthermore the model considers wear that changes the block geometry and thus the vibrational behaviour. With the presented model of a tyre tread block dynamic effects like friction induced vibrations are simulated. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On tangential stabilization in curvature driven flows of planar curves
Authors: Mikula Karol , Ševčovič Daniel
Published: October 2008

We discuss the role of tangential stabilization in a curvature driven flow of planar curves. The governing system of nonlinear parabolic equations includes a nontrivial tangential velocity functional yielding a uniform redistribution of grid points along the evolving family of curves preventing numerically computed curves from forming various instabilities. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermal annealing behavior of silica‐coated coaxial nanowires
Authors: Kim Hyoun Woo , Lee Jong Woo , Lee Changmu , Kebede Mesfin A.
Published: October 2008

The effects of thermal annealing on structural and optical properties of MgO‐core–silica (SiOx)‐shell nanowires have been investigated. The annealed nanostructures consisted of a crystalline MgO core surrounded by an amorphous SiOx shell layer, whereas the shell surface had become rough and an Mg2SiO4 phase appeared by annealing at a sufficiently high temperature of 800°C. Photoluminescence (PL) measurements of annealed MgO‐core/SiOx‐shell nanowires indicated that the overall intensities increased on increasing the annealing temperature, with the overall shapes of the emission spectra being independent of the annealing temperature from 600 to 1000°C. This study provides an insight into the annealing studies involving various coaxial nanowires. Copyright © 2008 John Wiley & Sons, Ltd.
Hypercalcemia and 13‐cis‐retinoic acid in post‐consolidation therapy of neuroblastoma
Authors: Marabelle Aurélien , Sapin Vincent , Rousseau Raphaël , Periquet Brigitte , Demeocq François , Kanold Justyna
Published: October 2008

We report 19 episodes of hypercalcemia in three children treated with 13‐cis‐retinoic acid (13‐cis‐RA) as a post‐consolidation therapy for high‐risk neuroblastoma. There was no concomitant overload in 13‐cis‐RA blood levels. Blood calcium fell after arrest of 13‐cis‐RA intake. Half dosage retinoid treatment resumption did not prevent the recurrence of hypercalcemia. Concomitant biological values showed massive bone resorption. Hence, hypercalcemia seemed not secondary to 13‐cis‐RA overload but rather to inter‐individual variability in its interaction with bone metabolism. Current guidelines in case of hypercalcemia are to reduce 13‐cis‐RA dosage. Instead we propose to maintain the therapeutic dosage, but to shorten the duration of courses. Pediatr Blood Cancer 2009;52:280–283. © 2008 Wiley‐Liss, Inc.
Quantitative phosphoproteomics – an emerging key technology in signal‐transduction research
Authors: Schreiber Thiemo B. , Mäusbacher Nina , Breitkopf Susanne B. , Grundner‐Culemann Kathrin , Daub Henrik
Published: October 2008

Protein phosphorylation is the most important type of reversible post‐translational modification involved in the regulation of cellular signal‐transduction processes. In addition to controlling normal cellular physiology on the molecular level, perturbations of phosphorylation‐based signaling networks and cascades have been implicated in the onset and progression of various human diseases. Recent advances in mass spectrometry‐based proteomics helped to overcome many of the previous limitations in protein phosphorylation analysis. Improved isotope labeling and phosphopeptide enrichment strategies in conjunction with more powerful mass spectrometers and advances in data analysis have been integrated in highly efficient phosphoproteomics workflows, which are capable of monitoring up to several thousands of site‐specific phosphorylation events within one large‐scale analysis. Combined with ongoing efforts to define kinase‐substrate relationships in intact cells, these major achievements have considerable potential to assess phosphorylation‐based signaling networks on a system‐wide scale. Here, we provide an overview of these exciting developments and their potential to transform signal‐transduction research into a technology‐driven, high‐throughput science.
Proteomics and phosphoproteomics for the mapping of cellular signalling networks
Authors: Preisinger Christian , von Kriegsheim Alex , Matallanas David , Kolch Walter
Published: October 2008

Proteomics is transitioning from inventory mapping to the mapping of functional cellular contexts. This has been enabled by progress in technologies as well as conceptual strategies. Here, we review recent advances in this area with focus on cellular signalling pathways. We discuss genetics‐based methods such as yeast two hybrid methods as well as biochemistry‐based methods such as two‐dimensional gel electrophoresis, quantitative proteomics, interaction proteomics, and phosphoproteomics. A central tenet is that by its ability to capture dynamic changes in protein expression, localisation and modification modern proteomics has become a powerful tool to map signal transduction pathways and deliver the functional information that will promote insights in cell biology and systems biology.
Plasma Etching and Roughening of Thin Polymeric Films: A Fast, Accurate, in situ Method of Surface Roughness Measurement
Authors: Kokkoris George , Vourdas Nikolaos , Gogolides Evangelos
Published: October 2008

A method is proposed to measure the root mean square surface roughness (hrms) of thin polymeric films on hard substrates during plasma etching. It utilizes in situ monitoring of the film thickness versus etching time by spectroscopic ellipsometry to extract the height distribution and hrms at the corner point (CP). The CP is the time instant where etching rate starts to gradually drop; it depends on the initial film thickness, and denotes the gradual exposure of the hard substrate to the plasma due to the advancement of the rough etch front. The hrms is found equal to approximately half of the remaining thickness at CP. The method compares well with atomic force microscopy measurements.

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Overexpression and elevated plasma level of tumor‐associated antigen 90K/Mac‐2 binding protein in colorectal carcinoma
Authors: Wu Chih‐Ching , Huang Yu‐Shan , Lee Li‐Yu , Liang Ying , Tang Rei‐Ping , Chang Yu‐Sun , Hsieh Ling‐Ling , Yu Jau‐Song
Published: October 2008

The cancer cell secretome may contain potentially useful biomarkers. Previously, we have analyzed the colorectal carcinoma (CRC) cell secretome. In this study, tumor‐associated antigen 90K (TAA90K)/Mac‐2 binding protein (Mac‐2BP), one of the CRC cell secreted proteins, was chosen for evaluation as a potential CRC biomarker because its mRNA level was also found to be significantly elevated in CRC tissues and in a more metastatic CRC cell line from the analysis of two public domain array‐based datasets. Immunohistochemical analysis of 241 CRC specimens showed that TAA90K/Mac‐2BP was positively detected in 52.7% of the tumors, but weakly or not detected in over 95% of the adjacent nontumor epithelial cells. The plasma TAA90K/Mac‐2BP levels were significantly higher in CRC patients (N = 280) versus healthy controls (N = 147) (7.77 ± 3.49 vs. 5.72 ± 2.67 μg/mL, p<0.001). Moreover, combination of TAA90K/Mac‐2BP and carcinoembryonic antigen (CEA) could outperform CEA alone in discriminating CRC patients from healthy persons in this case‐control study. Our results collectively indicate that analysis of cancer cell secretome is a feasible strategy for identifying cancer biomarker candidates, and the TAA90K/Mac‐2BP may be a potential CRC biomarker.
Fast‐response organic–inorganic hybrid light‐emitting diode
Authors: Fukuda Takeshi , Wei Bin , Suto Eiichi , Ichikawa Musubu , Taniguchi Yoshio
Published: October 2008

We demonstrated important changes produced on the modulation frequency of hybrid organic–inorganic light‐emitting diodes to examine the applicability as a light source for visible optical communications. The fabricated device structure was 4,4′‐bis[N ‐(1‐napthyl)‐N ‐phenyl‐amino]biphenyl/4,4′‐(bis(9‐ethyl‐3‐carbazovinylene)‐1,1′‐biphenyl:4,4′‐bis[9‐dicarbazolyl]‐2,2′‐biphenyl/ZnS/LiF/MgAg. This device showed an improvement in the modulation frequency using ZnS instead of an organic material, tris(8‐hydroxyquinoline)aluminum. A maximum cutoff frequency of 20.6 MHz was achieved.

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(© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low intensity directional switching of light in semiconductor microcavities
Authors: Schumacher Stefan , Kwong N. H. , Binder R. , Smirl Arthur L.
Published: October 2008

Recently it was demonstrated that in atomic vapors weak control beams can manipulate (or switch) the propagation direction of strong light beams [Dawes et al., Science 308, 672 (2005)]. As a semiconductor analog of such all‐optical switching, we present a proposal for similar manipulation and switching in planar semiconductor microcavities. Using a microscopic many‐particle theory, we investigate the spatio‐temporal dynamics of four‐wave mixing signals and related instabilities in these systems. Even though the underlying physical processes are different from atomic systems, we find that microcavities allow for reversible directional manipulation of light. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient VUV sensitization of Eu3+ emission by Tb3+ in potassium rare‐earth double phosphate
Authors: Mikhailik V. B. , Kraus H. , Dorenbos P.
Published: October 2008

The luminescence properties of K3Tb(PO4)2 activated by Eu3+ were studied at excitation over the 120–300 nm wavelength range. It is demonstrated that Tb3+ ions, exhibiting a strong absorption band in the vacuum‐ultraviolet (VUV), can provide efficient sensitisation of Eu3+ emission in this wave length range, giving rise to intense red luminescence at 150 nm excitation. A proof is given for the concept of VUV sensitisation enabling the engineering of luminescence materials with enhanced conversion efficiency of VUV radiation into visible light. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simultaneous Atlantic–Pacific blocking and the Northern Annular Mode
Authors: Woollings Tim , Hoskins Brian
Published: October 2008

A synoptic situation termed ‘high‐latitude blocking’ (HLB) is shown to occur frequently in both the Atlantic and Pacific sectors, and to result in flow anomalies very similar to those associated with the negative phase of the Northern Annular Mode (NAM) in the respective sector. There is a weak but significant link between the occurrence of HLB in the two sectors, with Atlantic HLB tending to lead Pacific HLB by 1–3 days. This link arises from rare events in which both sectors are almost simultaneously affected by a large‐scale wave‐breaking event which distorts the polar trough over Northern Canada. In several cases the tropospheric wave‐breaking occurs in tandem with a large‐scale disturbance of the stratospheric polar vortex.

There is, therefore, a physical link between the Atlantic and Pacific sectors, but analysis suggests that this does not contribute to determining the pattern of the NAM, as conventionally defined from monthly mean data. However, an alternative version of the NAM, derived directly from daily data, does appear to reflect this physical link. These conflicting results highlight the sensitivity of the NAM to the period over which data are averaged. Copyright © 2008 Royal Meteorological Society
Small‐scale precipitation variability in the Alps: Climatology in comparison with semi‐idealized numerical simulations
Authors: Zängl G. , Aulehner D. , Wastl C. , Pfeiffer A.
Published: October 2008

This study examines small‐scale precipitation patterns in a north‐Alpine region, and their dependence on the freezing level and on the crest‐level (700 hPa) wind direction and speed. On the one hand, measurements from a uniquely dense operational rain‐gauge network are analyzed for a period of 15 years (1991‐‐2005). Information on the ambient atmospheric fields was extracted from climate‐mode MM5 simulations driven with ECMWF (re‐analysis data. On the other hand, high‐resolution semi‐idealized MM5 simulations have been conducted, combining realistic topography with idealized atmospheric fields. The atmospheric flow parameters have been chosen to be representative of those used to classify the observational data, focusing on atmospheric conditions conducive to stratiform, orographically enhanced precipitation in the region under consideration.

The results of the data analysis indicate a pronounced tendency for local precipitation maxima in the lee of individual mountain ridges, whereas the variability between stations in the centre of wider valleys and stations on the windward foot of individual ridges is comparatively small. This points towards a strong contribution of local precipitation enhancement due to the seeder‐‐feeder mechanism, combined with downstream advection of the precipitating hydrometeors by the ambient winds. The data analysis also reveals that strong winds and high temperatures tend to shift the precipitation field towards the interior of the Alps, whereas low temperatures and weak winds favour precipitation maxima near the northern edge of the Alps. The semi‐idealized simulations are consistent with these findings, but their quantitative agreement with the observed precipitation patterns depends on the ambient flow conditions. The closest agreement is found for atmospheric conditions conducive to strong orographic lifting, for which our present idealized flow fields were designed. Lower skill is obtained for conditions not dominated by orographic lifting, which implies that future work should include a generalization of the idealized flow fields. Nevertheless, precipitation patterns generated with semi‐idealized simulations seem to be very promising to support the spatial interpolation of point measurements (such as are needed for precipitation climatologies), which currently is usually based on statistical methods rather than physically motivated structures. Copyright © 2008 Royal Meteorological Society
Hosoya polynomials of TUC4C8(R) nanotubes
Authors: Chen Jianfu , Xu Shoujun , Zhang Heping
Published: October 2008

For a connected graph G, the Hosoya polynomial of G is defined as H(G, x) = ∑{u,v}⊆V(G)xd(u, v), where V(G) is the set of all vertices of G and d(u,v) is the distance between vertices u and v. In this article, we obtain analytical expressions for Hosoya polynomials of TUC4C8(R) nanotubes. Furthermore, the Wiener index and the hyper‐Wiener index can be calculated. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
The dual sense of the term “element,” attempts to derive the Madelung rule, and the optimal form of the periodic table, if any
Authors: Scerri Eric R.
Published: October 2008

This article concerns various foundational aspects of the periodic system of the elements. These issues include the dual nature of the concept of an “element” to include element as a “basic substance” and as a “simple substance.” We will discuss the question of whether there is an optimal form of the periodic table, including whether the left‐step table fulfils this role. We will also discuss the derivation or explanation of the [n + ℓ, n] or Madelung rule for electron‐shell filling and whether indeed it is important to attempt to derive this rule from first principles. In particular, we examine the views of two chemists, Henry Bent and Eugen Schwarz, who have independently addressed many of these issues. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Sensitive analysis of anti‐HIV drugs, efavirenz, lopinavir and ritonavir, in human hair by liquid chromatography coupled with tandem mass spectrometry
Authors: Huang Yong , Gandhi Monica , Greenblatt Ruth M. , Gee Winnie , Lin Emil T. , Messenkoff Nicholas
Published: October 2008

A highly sensitive and selective method using liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) was developed and validated for the measurement of three antiretroviral agents, efavirenz, lopinavir and ritonavir, in human hair. Hair samples from adherent HIV‐infected patients on antiretroviral therapies were cut into about 1 mm length segments and drugs were extracted by first shaking the samples with methanol in a 37°C water bath overnight (>14 h), followed by methyl tert‐butyl ether/ethyl acetate (1:1) extraction under weak alkaline conditions. The extracted lopinavir and ritonavir were separated by reversed‐phase chromatography and detected by tandem mass spectrometry in electrospray positive ionization mode with multiple reaction monitoring (MRM), while efavirenz was monitored in negative ionization MRM mode. This method was validated from 0.01 to 4.0 ng/mg hair for ritonavir and 0.05–20 ng/mg hair for lopinavir and efavirenz by using 2 mg of a human hair sample. The interday and intraday assay precision (coefficients of variation, CV) for spiked quality control (QC) samples at low, medium and high concentrations were within 15% and accuracy ranged from 89% to 110%. Assay reproducibility was also demonstrated by analysis of incurred hair QC samples (CV <14%). No significant matrix ionization suppression was observed. This developed method allowed for the monitoring of these target medications in the hair samples of HIV‐infected women on antiretroviral therapy in an observational study using small amounts of hair. Copyright © 2008 John Wiley & Sons, Ltd.
Making classroom assessment more accountable to scientific reasoning: A case for attending to mechanistic thinking
Authors: Russ Rosemary S. , Coffey Janet E. , Hammer David , Hutchison Paul
Published: October 2008

When teachers or students assess the quality of ideas in science classes, they do so mostly based ontextbook correctness; ideas are good to the extent they align with or lead to the content as presented in the textbook or curriculum. Such appeals to authority are at odds with the values and practices within the disciplines of science. There has been significant amount of attention to this mismatch in the science education research literature, primarily with respect to experimentation and argumentation as core disciplinary means of assessing ideas. In this article, we call attention to another aspect of scientific reasoning: a focus on causal mechanisms in explaining natural phenomena. We highlight examples and research from the history and philosophy of science to clarify what scientists mean by “mechanism” and to make the case for its centrality. We then present an excerpt from a second‐grade class in which a student provides an incorrect mechanistic explanation, and the teacher gives priority to textbook correctness. As the conversation proceeds, the student shifts from mechanistic sensemaking to quoting terminology she does not understand. We argue that attention to mechanism in the classroom would better support student reasoning and better reflect disciplinary epistemology. © 2008 Wiley Periodicals, Inc.Sci Ed93:875–891, 2009
Building a financial sector in Central and Eastern Europe
Authors: Geiger Kurt
Published: October 2008

The public mission of the European Bank for Reconstruction and Development (EBRD) is to foster the transition toward an open, market‐oriented financial sector. It combines private‐sector principles in making investments, building institutions, privatizing banks, and raising equity with policy dialogue with all stakeholders, lawmakers, central banks, regulators, shareholders, and clients. Wellstructured creative individual projects, tailor‐made for the specific situation and executed in a pragmatic and successful way, provide a strong demonstration effect to market participants. Today the financial sector in Central and Eastern Europe is sound, competitive, and provides the fuel for sustained economic growth. Challenges remain, however. © 2008 Wiley Periodicals, Inc.
Asian tax review: Going green in Red China
Authors: Lipsher Laurence E.
Published: October 2008

Taxes in China are no laughing matter. The rules change often, and it takes a lot of energy to keep up. As more foreign investors enter the Chinese market, drawn by its size and dynamic entrepreneurial spirit, it can be very helpful to get frequent updates on the latest tax policies. This article talks about China's growing energy needs, increased interest in green technology, and how best to incentivize developers. The author, an expert on taxes, also provides updated information specifically from Hong Kong. © 2008 Wiley Periodicals, Inc.
Fetal abdominal cysts in the first trimester: prenatal detection and clinical significance
Authors: Sepulveda W. , Dickens K. , Casasbuenas A. , Gutierrez J. , Dezerega V.
Published: October 2008

Objective

In order to determine the clinical significance of fetal abdominal cysts detected in the first trimester, we reviewed our experience with such cases collected over a 5‐year period.

Methods

Five cases in which a fetal abdominal cyst was detected by ultrasound in the first trimester were identified. Information on the ultrasound findings, antenatal course and perinatal outcome was obtained in all cases.

Results

The abdominal cyst was confirmed by an early second‐trimester scan at 14–16 weeks in all cases, at which time no associated anomalies were detected. The standard detailed second‐trimester scan at 18–22 weeks demonstrated complete resolution in three cases. These women had an uneventful antenatal course, and normal newborn infants were delivered at term. However, one of these infants had intestinal malrotation, chronic abdominal distension and midgut volvulus requiring surgery at the age of 7 months. Among the remaining two cases in which the abdominal cyst persisted, one required prenatal aspiration at 19 weeks owing to significant enlargement and resolved. The other remained stable in size and was managed conservatively, but the infant required surgery at the age of 7 weeks owing to a choledochal cyst causing intermittent episodes of acholia.

Conclusion

Abdominal cysts in early pregnancy often resolve spontaneously or remain small and are usually associated with a good outcome. Nevertheless, as they can also be associated with serious underlying gastrointestinal pathological conditions, close surveillance in the perinatal period is advocated. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Umbilical venous volume flow in twin–twin transfusion syndrome
Authors: Gungor S. , Glosemeyer P. , Huber A. , Hecher K. , Baschat A. A.
Published: October 2008

Objectives

To examine umbilical venous volume flow (UVF) dynamics by twin status and disease severity in untreated twin–twin transfusion syndrome (TTTS).

Methods

In 70 cases of untreated TTTS, absolute UVF, UVF corrected for estimated fetal weight (UVF/kg), intertwin difference (ΔUVF/kg) and recipient to donor ratio (R/D‐UVF/kg) were calculated. Parameters for UVF were compared with respect to twin status and disease severity (early, Quintero Stages I and II; advanced, Stages III and IV).

Results

UVF/kg was higher in recipients than in donors and decreased with advancing stage in both twins (in recipients, 183.9 mL/kg/min vs. 145.6 mL/kg/min, P = 0.043; in donors, 137.5 mL/kg/min vs. 122.5 mL/kg/min, P = 0.033). Linear regression analysis demonstrated that the overall best correlation coefficient for ΔUVF/kg was obtained for the Doppler pulsatility index of the umbilical artery (t = − 4.536, P < 0.001). In advanced stage, absolute and weight‐corrected UVF were lower overall, while significant differences in intertwin volume flows persisted. The lowest flows were observed in hydropic recipients (median, 67.0 (range, 55.2–122.0) mL/kg/min vs. 180.8 (range, 59.1–565.4) mL/kg/min; P = 0.001).

Conclusions

In TTTS, UVF is significantly higher in recipients than in donors. With progression to advanced stage UVF/kg decreases in both twins as the magnitude of UVF that can be accommodated by the recipient declines. Further study of these dynamics in combination with cardiac performance parameters is warranted to refine diagnostic and prognostic assessment. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Impacts and solutions of control packets vulnerabilities with IEEE 802.11 MAC
Authors: Rachedi Abderrezak , Benslimane Abderrahim
Published: October 2008

In this paper, we focus on the medium access control (MAC), particularly the IEEE 802.11 and we deal with some hidden vulnerabilities based on the control packets CTS (clear to send) and ACK (acknowledgment). Through these vulnerabilities, we show two new smart attacks which were not dealt by the solutions proposed recently like the attack based on the RTS (request to send) packet vulnerability. The malicious node can exploit these vulnerabilities on the MAC protocol, in order to corrupt the monitoring and routing processes. Furthermore, we demonstrate the attacks through algorithms and we show how vulnerabilities can be exploited and how these attacks can be implemented by the attacker. The impact of these attacks is presented through simulation and implementation. Simulation and exprimental results show the impact of the attacks on the network. In addition, the experimental results demonstrate the feasibility of these real attacks and their exploitation. These experimentations allow us to confirm the simulation's results. Furthermore, in order to prevent these attacks, the solutions based on control packet authentication are presented. We propose two kinds of the solution one is cryptography independent and the other one is cryptography dependent. The evaluation and analysis of these solutions are investigated by analytic and simulations analysis. The simulations' results of the proposed solution show that the attacks are prevented and the negative impacts are significantly reduced. In addition, the security cost of the proposed solutions are investigated. Hence, the security costs are insignificant in comparison with the negative impact of these attacks. Copyright © 2008 John Wiley & Sons, Ltd.
Local Anesthetic Hernia Repair in Overweight and Obese Patients
Authors: Reid T. D. , Sanjay P. , Woodward A.
Published: October 2008

Background

Inguinal hernia repair under local anesthesia (LA) has many advantages and is associated with high patient satisfaction. However, there are concerns of exceeding the maximum safe dose of LA agents in overweight and obese patients. The aim of the present study was to establish whether inguinal hernia repair could be safely performed under LA in overweight and obese patients.

Methods

Patients who underwent elective LA hernia repair under a single consultant surgeon were studied retrospectively. Each patient received the same LA mixture developed at our hospital specifically for hernia repair. The mixture includes lignocaine and bupivocaine, both with adrenaline, made up to a volume of 100 ml with saline. Data were collected by case note review, and by postal and telephone surveys.

Results

A total of 125 patients who underwent LA hernia repair, in whom body mass index (BMI) was measured, were studied. Based on the World Health Organization (WHO) classification, there were 35 (28%) normal weight patients and 63 (72%) overweight (BMI ≥ 25 < 30) or obese (BMI ≥30) patients. The median BMI was 27 (range 19–38). The mean volumes of LA mixture used for each group were 58 ml and 62 ml, respectively. High day case rates of 91% and 84% were obtained for the two groups, respectively. Complications included three wound hematomas and three simple wound infections, with no significant differences between groups. One patient developed a recurrent hernia (<1%).

Conclusions

Local anesthetic inguinal hernia repair in the obese is safe and well tolerated. Use of a large volume local anesthetic mixture is recommended in overweight and obese patients.
Male rescue maintains low frequency parthenogenesis‐inducingWolbachiainfection inTrichogrammapopulations
Authors: Miura Kazuki , Yamanaka Takehiko , Suzuki Yoshito , Tagami Yohsuke , Davies Andrew Paul
Published: October 2008

Parthenogenesis‐inducing (PI)Wolbachiabacteria are reproductive parasites that cause infected (W+) female haplodiploid parasitoids to produce daughters without fertilization by males. Theoretically, PIWolbachiainfection should spread to fixation withinTrichogrammapopulations as males are no longer required to produce female offspring. Infections in some naturally occurringTrichogrammapopulations are, however, maintained at frequencies ranging from 4 to 26%. Here we describe discrete equation models to examine if the PIWolbachiainfection inTrichogrammapopulations can be maintained at relatively low frequencies by mating regularity. Model outcomes suggest the probability ofW+females mating could stabilizeWolbachiainfection frequency at low levels inTrichogrammapopulations. The primary mechanism maintaining low‐level PIWolbachiainfection inTrichogrammapopulations is reducing the survivorship from egg to adult in infected relative to uninfected females. The model successfully demonstrates that the relatively low PIWolbachiainfection frequency in host populations can be maintained by fertilization, or male rescue, of infected eggs, which avoids potentially hazardous gamete duplication that occurs duringWolbachia‐induced parthenogenesis.
Short‐term response of arbuscular mycorrhizal association to spider mite herbivory
Authors: Nishida Takaaki , Izumi Naoyuki , Katayama Noboru , Ohgushi Takayuki
Published: October 2008

We examined effects of aboveground herbivory by spider mites (Tetranychus urticae) on colonization and activity of arbuscular mycorrhizal fungi (AMF; Gigaspora margarita) using potted plants (Lotus japonicus). We evaluated changes in arbuscular mycorrhizal (AM) association two ways: (1) conventional trypan blue staining of mycorrhizal hyphae to examine AMF biomass in roots (mycorrhizal colonization) and (2) vital staining for a mycorrhizal enzyme (succinate dehydrogenase, SDH) to examine mycorrhizal activity (SDH activity). Mycorrhizal colonization and SDH activity started to increase 4 days after aboveground herbivory, and returned to the initial levels in the absence of mite herbivory in 7 and 12 days, respectively. These results suggest that the change in AM association in response to mite herbivory is a short‐term response.
Left atrial velocity vector imaging for the detection and quantification of left ventricular diastolic function in type 2 diabetes
Authors: Jarnert Christina , Melcher Anders , Caidahl Kenneth , Persson Hans , Rydén Lars , Eriksson Maria J.
Published: October 2008

Left ventricular (LV) diastolic dysfunction (DD) is diagnosed by Doppler echocardiography (DE) and Tissue Doppler imaging (TDI). Velocity vector imaging (VVI) evaluates myocardial deformation (strain). We studied left atrial (LA) deformation and volumes by VVI in relation to established Doppler‐derived indices of LV diastolic function in diabetic patients.

Material:

Using DE and TDI, 87 patients (males 49%; age 60±7 years) with type 2 diabetes mellitus were classified as having no (n=60), mild (n=13) or moderate (n=14) DD.

Results:

LA volume was larger in moderate (72.3±22.4 ml) than in mild DD (58.8±16.1 ml; p=0.01) and no DD (57.9±16.0 ml; p=0.01). LA roof strain distinguished no DD from mild and moderate DD (p=0.0073). Systolic LA strain correlated to total emptying fraction (r=0.70, p<0.0001), and inversely to LA volume (r=−0.35, p=0.0009). A cross‐validated analysis of no versus mild or moderate DD expressed by LA strain revealed a positive predictive value of 48% and negative of 84%.

Conclusion:

LA strain by VVI is impaired in patients with type 2 diabetes mellitus and mild or moderate LV DD. LA strain seems of value in distinguishing normal from abnormal diastolic function. VVI offers new information on regional LA function and LA volumes but has too limited discriminative power to detect early LV DD.
The Spectrum of Periodic Jacobi Matrices with Slowly Oscillating Diagonal Terms
Authors: Martíinez Carmen
Published: October 2008

We study the spectrum of periodic Jacobi matrices. We concentrate on the case of slowly oscillating diagonal terms and study the behaviour of the zeros of the associated orthogonal polynomials in the spectral gap. We find precise estimates for the distance from single eigenvalues of truncated matrices in the spectral gap to the diagonal entries of the matrix. We include a brief numerical example to show the exactness of our estimates.
Lamé Equation, Quantum Euler Top and Elliptic Bernoulli Polynomials
Authors: Grosset M.-P. , Veselov A. P.
Published: October 2008

A generalization of the odd Bernoulli polynomials related to the quantum Euler top is introduced and investigated. This is applied in order to compute the coefficients of the spectral polynomials for the classical Lamé operator.
Spectral Multipliers for Laplacians Associated with some Dirichlet Forms
Authors: Carbonaro Andrea , Mauceri Giancarlo , Meda Stefano
Published: October 2008

Let be the self-adjoint operator associated with the Dirichlet form

where ϕ is a positive C2 function, dλϕ = ϕdλ and λ denotes Lebesgue measure on ℝd. We study the boundedness on Lp(λϕ) of spectral multipliers of . We prove that if ϕ grows or decays at most exponentially at infinity and satisfies a suitable ‘curvature condition’, then functions which are bounded and holomorphic in the intersection of a parabolic region and a sector and satisfy Mihlin-type conditions at infinity are spectral multipliers of Lp(λϕ). The parabolic region depends on ϕ, on p and on the infimum of the essential spectrum of the operator on L2(λϕ). The sector depends on the angle of holomorphy of the semigroup generated by on Lp(λϕ).
Non-Terminating Basic Hypergeometric Series and the q-Zeilberger Algorithm
Authors: Chen William Y. C. , Hou Qing-Hu , Mu Yan-Ping
Published: October 2008

We present a systematic method for proving non-terminating basic hypergeometric identities. Assume that k is the summation index. By setting a parameter x to xqn, we may find a recurrence relation of the summation by using the q-Zeilberger algorithm. This method applies to almost all non-terminating basic hypergeometric summation formulae in the work of Gasper and Rahman. Furthermore, by comparing the recursions and the limit values, we may verify many classical transformation formulae, including the Sears–Carlitz transformation, transformations of the very well-poised 8φ7 series, the Rogers–Fine identity and the limiting case of Watson's formula that implies the Rogers–Ramanujan identities.