bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of the Internal Dynamics of Underactuated Robots
Authors: Seifried Robert
Published: March 2010

A robot is underactuated if it possesses less control inputs than degrees of freedom, e.g. due to passive joints. The analysis of the mechanical design of these kinds of underactuated robots often shows that they are non‐minimum phase, i.e. they have an internal dynamic which is not asymptotically stable. Therefore, feedback linearization is not possible, and output trajectory tracking becomes a very challenging task. It is shown that through an optimization procedure the mechanical design of an underactuated robot can be altered in such a way that the internal dynamics becomes stable. Thus feedback linearization of the underactuated robot becomes possible. In the optimization procedure, the design parameters are additional masses which are added to defined locations at different un‐actuated links of the robot. The optimization criteria is two‐stage and firstly requires that all eigenvalues of the linearized zero‐dynamics are in the left half‐plane and secondly that initial errors in the zero‐dynamics decay rapidly. Due to the two‐stage criteria computation the optimization problem is discontinuous. Also there might be many local minima. Therefore a particle swarm optimization procedure is used. The efficiency of this optimization approach is demonstrated by simulation of an underactuated robot. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mu‐Synthesis for Magnetic Bearings of Flywheel
Authors: Mystkowski Arkadiusz
Published: March 2010

In this paper, the μ‐Synthesis Control method is applied to control Active Magnetic Bearings (AMBs) Flywheel. The dynamics of the open‐loop system is influenced by external disturbances, nonlinearities, uncertainties and signal limits. Thus, a design methodology, which covers the practical issues of optimal robust control like the modelling of uncertainties, selection of optimal weighting functions is presented. The goal of this paper is the experimental evaluation robust performance of the AMBs system. The laboratory stand with the high speed rotor supported magnetically was built and presented. The stable operation, good stiffness of the rotor suspension and robust performances of the closed‐loop AMBs is reached. Finally, the success of the robust control is demonstrated through results of computer simulations and experimental results. The experimental results show the effectiveness of the control system as well as good vibrations reduction of the designed controllers. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Spiral Tribometer for Dynamic Friction Measurements
Authors: Al Natsheh Naser , Ostermeyer Georg‐Peter
Published: March 2010

Basically there exists a significant interest in dynamic friction models [1]. These dynamic models describe μ as a time dependent process parameter. The indentification of the belonging parameters needs a special kind of measurements. This is due to the fact that the measurements with the classical pin on disk arrangement give stationary values of μ only, the measurements of dynamic properties are even infeasible. A new advanced tribometer has been developed. This tribometer allows measurements of complex unsteady friction processes. The experimental characteristics and the realization of this novel tribometer are presented by concrete measurements. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Implementation of genetic algorithm for controlling the electromagnetic motor
Authors: Pecolt Sebastian , Krzyzynski Tomasz , Kuznicki Andrzej
Published: March 2010

The paper deals with the problem of implementing a genetic algorithm (GA) to calculate a pareto‐optimal function of voltage in time‐domain powering solenoids, used to control a linear electromagnetic motor (e.m.). The method proposed assumes minimising two criteria: the time of motion of the linear electromagnetic motor and the energy input. The results have been obtained for a set position with a narrow range of power supply. The work of electromagnetic motor is based on electromagnetic repulsion. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mixed algorithm in searches of mechanical system steady‐state conditions for low precision of the state estimation
Authors: Lipinski Krzysztof
Published: March 2010

This paper focuses on algorithms of numerical solution of nonlinear system of equations. Analytical formulas of their nonlinear functions my not be calculated with the requested precision. Additionally, analytical formulas of the partial derivatives are unknown. They are evaluated numerically by finite differences method. It effects in erroneous estimations. Described situation is critical when steady state conditions are searched for mechanical systems. According to the precision of the numerical procedures, their dynamic equations are known with limited precision. This same stands for the system's final conditions (obtained by a numerical integration). It the actual case, the classical Newton‐Raphson algorithm can be ineffective. As an alternative, a mixed search algorithm is proposed in the paper. By contrast to the classical algorithm, within the search direction defined by the Newton‐Raphson indication, (potentially erroneous) a local minimum is searched. Both the algorithms are tested on analytical functions; on randomized functions and on a model of a mechanical system. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analytical‐numerical Treatment of Elasticity and Thermoelasticity Problems for Inhomogeneous Orthotropic Cylindrical Bodies
Authors: Shevchuk Victor
Published: March 2010

This paper develops an approach to solving one‐dimensional elasticity and thermoelasticity problems for the case of inhomogeneous orthotropic cylindrical bodies. It is based on direct integration of differential equilibrium and compatibility equations in terms of stresses and reduction to the system of integral equations, which are effectively solved by the rapidly convergent iteration procedure. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Space‐Time Meshfree Collocation Method for PDEs
Authors: Netuzhylov Hennadiy , Zilian Andreas
Published: March 2010

An innovative Space‐Time Meshfree Collocation Method (STMCM) for solving systems of nonlinear ordinary and partial differential equations by a consistent discretization in both space and time is proposed as an alternative to established mesh‐based methods. The STMCM belongs to the class of truly meshfree methods, i.e. the methods which do not have any underlying mesh, but work on a set of nodes only, without an a priori node‐to‐node connectivity. A regularization technique to overcome the singularity‐by‐construction and to compute all necessary derivatives of the kernel functions is presented. The method combines the simplicity and straightforwardness of the strong‐form computational techniques with the advantages of meshfree methods over the classical ones, especially for coupled engineering problems involving moving interfaces. The key features of the proposed approach are: (i) no need to generate a mesh, (ii) simplified imposition of boundary conditions, (iii) no need to evaluate integral forms of governing equations, (iv) applicability to complex irregularly‐shaped domains. The proposed STMCM is applied to linear and nonlinear ordinary and partial differential equations of different types and its accuracy and convergence properties are studied. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Numerical Model of a Drug Particle Dissolving in a Dissolution Test Apparatus
Authors: McMahon Niall M. , Crane Lawrence J. , Ruskin Heather J. , Crane Martin , D'Arcy Deirdre M. , Healy Anne‐Marie , Corrigan Owen I.
Published: March 2010

The dissolving compact, or tablet, is the most widely used method of drug delivery. Dissolution tests are used to ensure consistency during tablet manufacture, to assess the dissolution characteristics of a particular tablet design, to establish in vitro/in vivo correlations, and to predict how the drug will perform in the body. Dissolution tests also form a part of the drug approval process. The United States Pharmacopeia (USP) Type 2 Paddle Dissolution Apparatus,from here on referred to as the USP apparatus, is a standard dissolution test device, used by the Food and Drug Administration (FDA) and the pharmaceutical industry. Although the USP apparatus is much used, detailed theoretical descriptions of its characteristics are still not well developed. This work considers one possible end state of a dissolving tablet, i.e. fragmentation into small particles with dissolution continuing from the disintegrated solid masses. A framework for calculating the motion of and mass transfer from a drug particle moving through the USP apparatus is outlined. Calculations demonstrate that small particles move with the USP apparatus flow and that, for small particles below a critical diameter, natural convection and radial diffusion dominate, i.e. forced convection effects can be neglected for small particles. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The frequency transfer function corresponding to hand‐arm system
Authors: Pop A. F. , Arghir M.
Published: March 2010

The paper presents a study regarding the frequency transfer function corresponding to hand‐arm system. Theoretical the frequency transfer function obtains applying the Laplace function for the differential equations of moving system. This is a part of the study regarding the mechanical vibrations action over the hand‐arm system. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Brief preliminary design for a method of FMS machine tools subsystem selection
Authors: Gola Arkadiusz , Świć Antoni
Published: March 2010

The article presents the main points of methodology of machine tools subsystem selection for a flexible manufacturing system. In particular, it shows the main algorithm and stages of the methodology which is based on computer database systems, algorithms of elimination and method of multicriteria optimisation. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An L2 model for selfadjoint elliptic differential operators with constant coefficients on bounded domains
Authors: Behrndt Jussi , Rohleder Jonathan
Published: March 2010

The selfadjoint realization of a second order elliptic differential expression with Dirichlet boundary conditions is shown to be unitarily equivalent to the maximal multiplication operator with the independent variable in an explicit L2 model space. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Diagnostics of a combustion process in the aircraft radial engine
Authors: Gęca Michał , Litak Grzegorz , Wendeker Mirosław , Jakliński Piotr , Czarnigowski Jacek , Pietrykowski Konrad
Published: March 2010

We present the statistical nonlinear analysis of time series applied to indicated combustion pressure. Using nonlinear methods we analyzed dynamics of a multi cylinder aircraft radial engine in the presence of cyclic perturbations in a single cylinder. The perturbations have been caused by variation of an air/fuel ratio via injection timing. Identification of the disturbed cylinder has been done successfully by adopting wavelet and multifractal analysis. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rapid fault‐tolerant control prototyping for mobile robots
Authors: Moczulski Wojciech , Panfil Wawrzyniec , Przystałka Piotr
Published: March 2010

The main purpose of the paper is to present a fault‐tolerant control system of an autonomous mobile robot. The authors present a framework for rapid prototyping of a behavior‐based control system relying on tools and technologies of the Microsoft R Robotics Developer Studio. Fault detection and isolation is carried out with the help of the model‐based and knowledge‐based diagnostics. The first approach is developed by applying recurrent neural networks for residual generation and fuzzy logic for their evaluation. The second approach depends on scalar feature estimation and fuzzy reasoning. Basing on this information rules represented in the form of a decision table are applied for robot's behavior reconfiguration. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An Analysis of Drug Dissolution Rates in the USP 24 Type 2 Apparatus
Authors: McDonnell David , Redmond Brendan , D'Arcy Deirdre M , Healy Anne Marie , Corrigan Owen I
Published: March 2010

This paper applies boundary layer theory to the process of drug dissolution in the USP 24, Type 2 Apparatus. The mass transfer rate from the top flat surface of a compact in various positions within the device is evaluated by means of a Pohlhausen integral method. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Descriptions of contacts in the presence of wear debris
Authors: Zmitrowicz Alfred
Published: March 2010

The mechanism of abrasive wear involves formation and circulation of debris particles detached from rubbing solids. The loose wear particles form a more or less continuous intermediate layer which separates the sliding surfaces. The layer is treated as a single continuum with own kinematics and constitutive relations. The removal of material from rubbing solids, continuum based models and granular models of wear debris are discussed in the contribution. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study on the aluminium phosphate bonded SiC refractory performance and how it is influenced by oxidation and chemical attack
Authors: Pica E. M. , Rodean C. P.
Published: March 2010

Aluminium reduction cells service life and cell efficiency are strongly influenced by the side wall refractory lining. The aluminum phosphate bonded SiC refractories developed by us, instead of the carbon ones, have increased the cell capacity and productivity by the larger anode surfaces. In order to rank performances of various SiC products were carried out specific laboratory tests. The results of our research concerning materials made from aluminum phosphate bonded SiC showed that they are refractories with a high corrosion resistance and performances close to the bricks made of silicon nitride bonded silicon carbide. By extrapolation of the present study's results we can anticipate an increased service life of electrolysis cells that have such side walls. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural Analysis on Nanoscale
Authors: Wackerfuß Jens
Published: March 2010

Atomic structures, exhibiting a physical dimension in a range of 1‐100 nanometers provide a basis for novel applications in nanotechnology. In molecular mechanics the formalism of the finite element method can be exploited to analyze the behavior of atomic structures in a computational efficient way. Based on the atom‐related consideration of the atomic interactions, a direct correlation between the type of the underlying interatomic potential and the design of the related finite element has been developed. Each type of potential is represented by a specific finite element. A general formulation that unifies the various finite elements is proposed. The mesh generation can be performed using well‐known procedures typically used in molecular dynamics. Although adjacent elements overlap, a double counting of the element contributions (as a result of the assembly process) can not occur a priori in this new formulation. As a consequence, the assembly process can be performed efficiently line by line. The presented formulation can easily be implemented in standard finite element codes and can be applied to various interatomic potentials. As an example, the method is applied in order to model the structural response of pristine and defective carbon nanotubes. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the machine structure on micro milling process
Authors: Shi Yinuo , von Wagner Utz , Mahr Frederik , Uhlmann Eckart
Published: March 2010

To achieve accurate machining using the micro milling process, precise tools (diameter range 0.2 mm–2 mm) are used. Because of the special properties of the micro milling tools and the related machine structures, it is not enough to assign the classical technique in macro milling process, e.g. stability prediction respecting only the dynamics of the tool/workpiece, directly to analyze the micro milling process. It is proved to be required also to take characteristics of the entire machine structure into account. Therefore, the mechanical vibration research of the micro milling machine structure is necessary, and subsequently the modeling of the structure as a multiple body system is described. The identification of the natural frequencies of a micro milling machine structure by means of the classical modal analysis is shown, and the influence of the structure is verified by comparing the surface roughness of the manufactured workpiece in experimental testings. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Non‐linear hypotheses of deformation of flat cross sections of elastic sandwich beam.
Authors: Magnucka‐Blandzi Ewa
Published: March 2010

The main goal of the paper is a comparison of three non‐linear hypotheses of deformation of flat cross sections of an elastic sandwich beam. Three‐layered simply supported beam is under uniformly distributed load (pressure). Studied beam has two faces and a metal foam core. Mechanical properties of the isotropic metal foam core of the beam vary across the thickness of the beam. Fields of displacements (geometric models of non‐linear hypotheses) are described. The results of solution of the deflection problem are presented at Figures. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of a quadratic element formulation based on the X‐FEM and NURBS surfaces
Authors: Haasemann Georg , Kästner Markus , Prüger Stefan , Ulbricht Volker
Published: March 2010

The FE‐simulation of inhomogeneous structures such as composite materials, biological tissues or foams requires the generation of respective finite element meshes. The Extended Finite Element Method (X‐FEM) allows for an efficient modelling technique where the element boundary needs not to be aligned to the interfaces. In this paper, a new plane element based on the X‐FEM and quadratic shape functions will be presented. This element allows for the description of curved material interfaces inside the element domain. The computation of the element stiffness matrix requires a numerical integration process which accounts for the discontinuous fields. In the case of a curved interface, the triangulation of the element domain as applied for linear element formulations is inappropriate. Hence, Non‐Uniform Rational B‐Spline (NURBS) surfaces are used to evaluate the integrals numerically. Finally, the results of different examples will show the properties and the quality of this element formulation. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamical effects at material instability phenomena
Authors: Béda Peter B.
Published: March 2010

In a phenomenon called the Portevin‐Le Chatelier (PLC) effect negative rate dependence is coupled with the appearance of a self‐sustained oscillatory behavior in solid bodies. When PLC is treated as a type of dynamic material instability, the tools of the theory of dynamical system can be applied. The results of such investigation lead to an interpretation of PLC as a flutter type of loss of stability. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanoindentation Experiments at Elevated Temperatures for the Determination of Mechanical Solder Material Properties
Authors: Müller Wolfgang H. , Worrack Holger , Sterthaus Jens , Wilden Johannes
Published: March 2010

The continuous effort of modern electronic industry is the miniaturization of microelectronic components. In order to guarantee the reliability of the joining process, the quantitative knowledge of the solder material properties is very important, especially the values of Young's modulus, Nanoindentation hardness and yield stress. However, small‐sized microelectronic devices require the fabrication of small sized specimens and the use of corresponding miniature material tests. At the Technische Universität Berlin nanoindentation tests are applied. Moreover the material properties at elevated temperature are of particular interest in order to characterize the solder materials more detailed. This work describes the setup and the elevation of high‐temperature nanoindentation tests in context with first results for selected materials. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical simulation of a multi‐contact detection technique for foreign particles in closed food containers
Authors: Osorio Anuhar , Schmidt Tobias , Beronov Kamen , Forstner Judith , Benning Rainer , Delgado Antonio
Published: March 2010

In the presented work the basis of a novel method for detecting foreign solid inclusions in closed glass bottles and cans containing liquid food are presented. The new method is based on an automatic recording and analysis of multi‐contact oscillatory signals of the food‐container‐particle (F‐C‐P) system. In this work, two different active mechanisms for positioning the foreign particles next to the wall of the bottle are studied and relevant numerical simulations are presented. In the first case, a bottle filled with water moves linearly with constant acceleration, while in the second case the bottle rotates around its longitudinal axis at a constant angular velocity. The obtained numerical results permit the selection of optimal locations for the detection system components. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of unusual truncated forms of nucleocapsid protein in MDCK cells infected by Avian influenza virus (H9N2)
Authors: Liu Ning , Song Wenjun , Wang Pui , Lee Kim‐Chung , Cai Zongwei , Chen Honglin
Published: March 2010

Unusual truncated forms of nucleocapsid protein (NP) were identified in the lysate of MDCK cells infected by Avian influenza virus (H9N2) using MS‐based proteomics approach. Moreover, O‐sulfonation that was considered as an unusual modification was identified in one of the tryptic peptides from the truncated NP. The findings might have implications on better understanding on the role of nucleoprotein in Avian influenza virus–host interaction.
Evaluation of blood collection tubes using selected reaction monitoring MS: Implications for proteomic biomarker studies
Authors: Randall Sarah A. , McKay Matthew J. , Molloy Mark P.
Published: March 2010

An emphasis of current proteomic research is the validation of plasma protein biomarkers. The process of blood collection itself is critical to the accuracy and reproducibility of quantitative biomarker assays. We have developed selected reaction monitoring (SRM) assays to analyse thirteen abundant plasma proteins and evaluated the impact of three different blood collection tubes on the levels of these proteins. We also assessed the implications of the time taken to analyse plasma samples by evaluating the recovery of these proteins. We showed that SRM detects minor differences in the levels of some proteins which can be attributed to collection tube type. The average recovery for 12 of 18 assays was higher for proteins that were collected in tubes containing protease inhibitors compared to conventional collection tubes. For five of the assays, the differential recovery was statistically significant. Delaying MS analysis of a freeze‐thawed sample for 1 hour showed greatly reduced recovery of these analytes; however differences attributed to tube type were only evident at the baseline timepoint. Finally, we assessed the natural variation of circulating levels of these proteins in a cohort of seven healthy individuals. This study provides useful information for researchers contemplating blood collection for undertaking protein biomarker studies.
Human galectin‐3 interacts with two anticancer drugs
Authors: Bogoeva Vanya P. , Varriale Antonio , John Constance M. , D'Auria Sabato
Published: March 2010

Human galectin‐3 (hGal‐3) is a mammalian lectin involved in regulation of RNA splicing, apoptosis, cell differentiation, and proliferation. Multimerized extracellular hGal‐3 is thought to crosslink cells by binding to glycoproteins and glycosylated cancer antigens on the cell surface or extracellular matrix. Fluorescence spectroscopy and circular dichroism were used to study the interaction of hGal‐3 with two anticancer agents: bohemine and Zn porphyrin (ZnTPPS4). The dissociation constant (kD) for binding of bohemine with hGal‐3 was kD 0.23±0.05 μM. The hyperbolic titration curve indicated the presence of a single bohemine binding site. The binding of ZnTPPS4 to hGal‐3 (with and without lactose) is of high affinity having kD=0.18–0.20 μM and is not inhibited by lactose, indicating that ZnTPPS4 and carbohydrate bind different sites. Circular dichroism spectra of the hGal‐3 complexes suggested that the binding of the hydrophobic compounds changed the hGal‐3 secondary structure. In summary, we show that two compounds with anticancer activity, bohemine and ZnTPPS4, have high affinity for hGal‐3 at a site that is distinct from its carbohydrate site. Since hGal‐3 binds to several carbohydrate cancer antigens, the results suggest that it may have utility in the targeted delivery of drugs for cancer.
Modifications of human total serum N‐glycome during liver fibrosis–cirrhosis, is it all about immunoglobulins?
Authors: Klein André , Michalski Jean‐Claude , Morelle Willy
Published: March 2010

The study of the total serum N‐glycome during liver cirrhosis has demonstrated numerous alterations. The identification of the glycoproteins carrying these modifications and their relative contribution to the modification of the total serum N‐glycome has shown the important role of IgA and IgG. The possible mechanisms of glycosylation alteration of the Igs and of liver secreted glycoproteins, the consequences in the pathophysiology of cirrhosis and their relation to the biomarkers of liver diseases are also discussed in the present review.
A water‐soluble parthenolide analogue suppresses in vivo prostate cancer growth by targeting NFκB and generating reactive oxygen species
Authors: Shanmugam Rajasubramaniam , Kusumanchi Praveen , Cheng Liang , Crooks Peter , Neelakantan Sundar , Matthews William , Nakshatri Harikrishna , Sweeney Christopher J.
Published: March 2010

BACKGROUND

To characterize the molecular changes associated with DMAPT‐induced prostate cancer cell death and its in vivo activity.

METHODS

CWR22Rv1 and PC‐3 were subjected to flow cytometry, electrophoretic mobility shift assays, and Western blot studies to measure DMAPT's ability to generate reactive oxygen species (ROS), inhibit NFκB DNA binding, and cause changes in anti‐apoptotic proteins. N‐acetyl cysteine (NAC) and short hairpin RNA (shRNA) were used to determine the contribution of ROS and JNK2 activation, respectively. The BrdU incorporation assay was used to measure proliferation and trypan blue studies assessed cell viability after DMAPT treatment. The in vivo activity of DMAPT as a single agent and in combination with bicalutamide or docetaxel was assessed in a subcutaneous xenograft model with athymic nude female mice.

RESULTS

DMAPT generated ROS with subsequent JNK activation and inhibited NFκB DNA binding and expression of NFκB‐regulated anti‐apoptotic proteins. DMAPT increased necrotic and apoptotic cell death in a cell‐type‐dependent manner and both types of cell death were blocked by NAC. Additionally, shRNA JNK2 partially blocked the anti‐proliferative activity of DMAPT. DMAPT inhibited CWR22Rv1 and PC‐3 cellular proliferation by 100% with 10 and 20 µM respectively and in vivo, DMAPT was more effective at inhibiting growth than biclutamide (CWR22v1) and docetaxel (PC‐3).

CONCLUSIONS

DMAPT promotes cell death by both generating ROS and inhibition of NFκB. Its in vivo activity supports the conduct of clinical trials in patients with castrate‐resistant disease. Prostate 70: 1074–1086, 2010. © 2010 Wiley‐Liss, Inc.
Study of phase change memory cell with inserting buffer layer
Authors: Wu Liangcai , Zhou Xilin , Song Zhitang , Liu Yan , Ni Henan , Gong Yuefeng , Rao Feng , Yao Donglin , Liu Bo , Song Sannian , Feng Songlin
Published: March 2010

TiO2 and HfO2 with different electrical conductivity were used as buffer layer for phase change memory (PCRAM) cell, where Si‐Sb‐Te alloy was used as storage medium in the PCRAM cell. The electrical properties of the cells with and without buffer layer were compared through resistance‐voltage measurements. It is found that the PCRAM cell with both TiO2 and HfO2 buffer layer has relative low operation voltage. Furthermore, the inserting TiO2 buffer layer can also improve the device stability. It is considered that buffer layer with suitable electrical conductivity is needed for the PCRAM cell, especially in future high density storage. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation on the conversion efficiency of InGaN solar cells fabricated on GaN and ZnO substrates
Authors: Inoue S. , Katoh M. , Kobayashi A. , Ohta J. , Fujioka H.
Published: March 2010

By the use of a device simulator that takes the quantum effect into account, we have investigated the characteristics of InGaN solar cells stacked coherently on GaN or ZnO substrates. We have found that it is necessary to fabricate non‐polar cells, N‐polar cells with p–i–n structures, or III‐polar cells with n–i–p structures in order to achieve high conversion efficiency. InGaN solar cells grown on GaN substrates and on ZnO substrates exhibit almost the same conver‐ sion efficiencies, in spite of the difference in the intensities of the strains in the InGaN films. Taking the smaller lattice mismatch between InGaN and ZnO into account, we conclude that the use of ZnO substrates, which makes the growth of thick InGaN films with high In concentrations simpler to achieve, is advantageous in the fabrication of high conversion efficiency InGaN solar cells. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A case study in model‐based testing of specifications and implementations
Authors: Miller Tim , Strooper Paul
Published: March 2010

Despite the existence of a number of animation tools for a variety of languages, methods for employing these tools for specification testing have not been adequately explored. Similarly, despite the close correspondence between specification testing and implementation testing, the two processes are often treated independently, and relatively little investigation has been performed to explore their relationship. This paper presents the results of applying a framework and method for the systematic testing of specifications and their implementations. This framework exploits the close correspondence between specification testing and implementation testing. The framework is evaluated on a sizable case study of the Global System for Mobile Communications 11.11 Standard, which has been developed towards use in a commercial application. The evaluation demonstrates that the framework is of similar cost‐effectiveness to the BZ‐Testing‐Tools framework and more cost‐effective than manual testing. A mutation analysis detected more than 95% of non‐equivalent specification and implementation mutants. Copyright © 2010 John Wiley & Sons, Ltd.
Participation in science practices while working in a multimedia case‐based environment
Authors: Kang Hosun , Lundeberg Mary A.
Published: March 2010

The purpose of this study was to investigate how two female students participated in science practices as they worked in a multimedia case‐based environment: interpreting simulated results, reading and writing multiple texts, role‐playing, and Internet conferencing. Using discourse analysis, the following data were analyzed: students' published web posters, Internet conferencing logs between American and Zimbabwean university students, and a focus group interview. Three constructs supported the development of these students' identities in practice: (a) multimedia cases creating emotional involvement; (b) authoring web posters, and role‐playing situated in cross‐cultural social networks; and (c) altruism associated with relevant global topics. The investigators argue that educators and developers of online learning environments consider social contexts, authoring, and opportunities for cross‐cultural interaction to support participation in science practices. © 2010 Wiley Periodicals, Inc. J Res Sci Teach 47: 1116–1136, 2010
Detection and attribution of climate change: a regional perspective
Authors: Stott Peter A. , Gillett Nathan P. , Hegerl Gabriele C. , Karoly David J. , Stone Dáithí A. , Zhang Xuebin , Zwiers Francis
Published: March 2010

The Intergovernmental Panel on Climate Change fourth assessment report, published in 2007 came to a more confident assessment of the causes of global temperature change than previous reports and concluded that ‘it is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent except Antarctica.’ Since then, warming over Antarctica has also been attributed to human influence, and further evidence has accumulated attributing a much wider range of climate changes to human activities. Such changes are broadly consistent with theoretical understanding, and climate model simulations, of how the planet is expected to respond. This paper reviews this evidence from a regional perspective to reflect a growing interest in understanding the regional effects of climate change, which can differ markedly across the globe. We set out the methodological basis for detection and attribution and discuss the spatial scales on which it is possible to make robust attribution statements. We review the evidence showing significant human‐induced changes in regional temperatures, and for the effects of external forcings on changes in the hydrological cycle, the cryosphere, circulation changes, oceanic changes, and changes in extremes. We then discuss future challenges for the science of attribution. To better assess the pace of change, and to understand more about the regional changes to which societies need to adapt, we will need to refine our understanding of the effects of external forcing and internal variability. Copyright © 2010 John Wiley & Sons, Inc.

This article is categorized under:

Paleoclimates and Current Trends > Detection and Attribution
Synthesis, Crystal Structure and Vibrational Spectra of Barium Cyclotetraphosphate Hydrate Ba2(P4O12)∙3.5H2O
Authors: Höppe Henning A. , Kazmierczak Karolina , Daub Michael
Published: March 2010

Barium tetrametaphosphate hydrate Ba2(P4O12)∙3.5H2O was synthesized as a single‐phase crystalline powder starting from an aqueous solution of barium hydroxide and phosphorus pentoxide at 300 K. Ba2(P4O12)∙3.5H2O crystallizes in a new structure type in which the Ba2+ ions form a distorted hexagonal diamond‐like arrangement with the (P4O12)4– anions in the trigonal prismatic voids (Ba2(P4O12)∙3.5H2O, C2/c, Z = 4, a = 777.3(2), b = 1297.6(2), c = 1346.1(3) pm, b = 95.38(2)°, wR2 = 0.071, R1 = 0.018, 1180 reflections, 118 parameters). The vibrational spectra of Ba2(P4O12)∙3.5H2O and its thermal behavior up to 720 K are also reported.
Syntheses, Structures and Electrochemistry Properties of Two Dicyanamide Manganese(III) Complexes [Mn(5‐Brsalen)(dca)]·CH3OH and [Mn(3‐Meosalphen)(dca)(H2O)]
Authors: Wang Ting‐Ting , Xie Ji‐Min , Xia Chang‐Kun , Wu Yun‐Long , Jing Jun‐Jie
Published: March 2010

Two manganese(III)‐dicyanamide compounds, [Mn(5‐Brsalen)(dca)]·CH3OH (1) and [Mn(3‐Meosalphen)(dca)(H2O)] (2) (dca = dicyanamide anion, [N(CN)2]–), were synthesized and characterized by elemental analysis, IR spectroscopy, single‐crystal X‐ray structure analysis, and cyclic voltammetry. The structure of complex 1 is an infinite zigzag chain of hexacoordinate MnIII ions, in which the adjacent manganese atoms are connected by dca in μ1,5‐bridging mode. The molecular structure of complex 2 consists of a hexacoordinate MnIII atom, which generates a slightly distorted octahedral arrangement, and a dimer structure is formed by intermolecular hydrogen bonding interactions. The electrochemical properties of the two complexes were measured by cyclic voltammetry.
Ammonolysis of 1,2‐Bis[dichloro(methyl)silyl]ethane. On the Structure of 1,3,6,8‐Tetramethyl‐2,7,11,12‐tetraaza‐1,3,6,8‐tetrasila‐tricyclo[6.2.1.13,6]‐dodecane
Authors: Motz Günter , Schmalz Thomas , Glatz Germund , Kempe Rhett , Milius Wolfgang , Wrackmeyer Bernd
Published: March 2010

Ammonolysis of 1,2‐bis[dichloro(methyl)silyl]ethane afforded a crystalline tricyclic silazane along with polymeric material. The crystalline material could be isolated in pure state. It was analyzed by 1H, 13C, 15N and 29Si NMR spectroscopy in solution, by 13C, 15N and 29Si MAS NMR spectroscopy in the solid state, as well as by single‐crystal and powder X‐ray diffraction. The title compound exists as a single isomer in solution, whereas in the solid state the presence of several modifications is indicated, in particular by the solid‐state MAS NMR spectra.
A Novel (42,62,82)‐a 3D Copper(I) Complex Based on the Ligand 2,4,5‐Tri(4‐pyridyl)‐imidazole
Authors: Wang Li , Gu Wen , Deng Jun‐Xiu , Zeng Ling‐Fei , Liu Xin
Published: March 2010

A novel 3D copper(I) coordination polymer [Cu8(ptim)8·3CH3CH2OH·2H2O] with the ligand 2,4,5‐tri(4‐pyridyl)‐imidazole (Hptim) was synthesized and characterized. During the reaction, Hptim is oxidized by copper(II) and loses its hydrogen atom from the imidazole ring to add one coordination position. The novel complex has a 3D pillared double‐layer network. The topological analysis of the crystal structure shows that the complex can be simplified to a 4‐connected network with the Schläfli symbol (42,62,82). The novel complex shows remarkable thermal stability because of the neutral 3D polymeric structure. The investigation of its fluorescent property shows that the complex can induce fluorescence quenching of the ligand, which indicates that Hptim can act as a chemosensor for detecting Cu+ ions in high selectivity.
Gallium–Gallium Bonds Bridged by Functionalized Carboxylato Ligands
Authors: Uhl Werner , Bock Henrik R. , Kösters Jutta , Voß Matthias
Published: March 2010

Treatment of the tetraalkyldigallium compound R2Ga–GaR2 [R = CH(SiMe3)2] (1) with a large number of different functionalized carboxylic acids afforded dicarboxylatodigallium compounds R2Ga2(μ‐O2C–R)2, in which two carboxylato ligands bridge the Ga–Ga bonds. The chelating ligands have additional nitrogen, oxygen or phosphorus donor atoms and may be suitable to act as Lewis‐bases to yield supramolecular aggregates in future investigations. Four compounds have been characterized by crystal structure determinations. One gave unprecedented dimeric formula units in the solid state by Ga–N interactions. The similar reaction with isonicotinic acid resulted in the cleavage of the Ga–Ga bond. A tetragallium compound was formed in which four isolated metal atoms were bridged by four organic ligands to give a square molecular core.
Single‐Access Retroperitoneoscopic Adrenalectomy (SARA) Versus Conventional Retroperitoneoscopic Adrenalectomy (CORA): A Case–Control Study
Authors: Walz Martin K. , Groeben Harald , Alesina Piero F.
Published: March 2010

Background

Stimulated by the concept of Natural Orifice Transluminal Endoscopic Surgery (NOTES), minimizing the access even further has become a new trend in minimally invasive surgery. We compare our recently described new method of endoscopic single‐access adrenalectomy with the conventional retroperitoneoscopic approach in a matched‐pairs study.

Methods

Fifty single‐access retroperitoneoscopic adrenalectomies (SARA) were performed in 47 selected patients suffering from Conn’s adenomas (n = 20), pheochromocytomas (n = 15), Cushing’s adenomas (n = 6), and other diseases (n = 6). For SARA, a single 2‐cm skin incision beneath the 12th rib was used. Following creation of the retroperitoneal space with the rigid endoscope, dissection was carried out single‐handed. Another 47 patients served as control group; they were treated by the traditional retroperitoneoscopic three‐port approach (CORA). Patients were matched with respect to gender, body mass index, diagnoses, tumor size, and tumor site.

Results

Mortality was zero and no major complications occurred in both groups. SARA was completed in 41 cases (86%). The overall complication rate was 8.5% in SARA and 6.4% in CORA. Operative time was longer for SARA (56 ± 28 min) than for CORA (40 ± 12 min) (P < 0.05). Postoperatively, pain medication was administered in 47% of SARA patients and in 75% of CORA patients (P = 0.01). Mean hospital stay was 2.4 ± 0.7 days (SARA) and 3.1 ± 1.2 days (CORA) (P < 0.01).

Conclusions

Because feasibility and safety of SARA could be demonstrated in a large group of selected patients, this surgical technique may represent a new milestone in minimally invasive endocrine surgery.
Does Analysis of Biomarkers in Tumor Cells in Lymph Node Metastases Give Additional Prognostic Information in Primary Breast Cancer?
Authors: Falck Anna‐Karin , Fernö Mårten , Bendahl Pär‐Ola , Rydén Lisa
Published: March 2010

Background

Prognostic and treatment‐predictive biomarkers in primary breast cancer are routinely analyzed in the primary tumor, whereas metastatic tumor cells in lymph node metastases are not characterized. The present study aimed to define the concordance between biomarkers in matched pairs of breast cancers and lymph node metastases and to relate their expression to clinical outcome.

Methods

Patients with primary breast cancer treated with adjuvant tamoxifen for 2 years were included. A tissue microarray of primary tumors and lymph node metastases was constructed, and estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and Ki67 were analyzed immunohistochemically in 262, 257, 104, and 101 patients, respectively. Five years’ distant disease‐free survival (DDFS) was used as the primary end point.

Results

The concordance for biomarker expression in primary tumors and corresponding lymph node metastases was 93% for ER, 84% for PR, 97% for HER2, and 85% for Ki67. The discordant cases for HER2 status were all negative in the tumor but positive in the node. ER positivity was a significant independent predictor of improved 5‐year DDFS when analyzed in the primary tumor as well as in the lymph node metastases. Ki67 positivity analyzed in both locations correlated with shortened DDFS. HER2 positivity at both locations was an indicator of early relapse.

Conclusions

The concordance for the biomarkers analyzed in matched pairs of primary tumors and lymph node metastases was high. Moreover, survival analyses showed that the expression of biomarkers in lymph node metastases can provide prognostic information when no analyses of the primary tumor can be done. Treatment selection based on biomarkers in the lymph node is a topic for further studies.
Relationship Between Geographical Origin and Fatty Acid Composition of Turkish Virgin Olive Oils for Two Harvest Years
Authors: Diraman Harun , Saygi Hülya , Hisil Yaşar
Published: March 2010

In this study, the fatty acid compositions of Turkish virgin olive oils produced in the Izmir province, an important olive production region of Turkey, were classified by chemometric methods: principal component analysis (PCA) and discriminant analysis (DA). A total of 103 oil samples were examined over the course of two harvest years (2001–2002 and 2002–2003). The samples were divided into five groups according to olive growing zones: North (Ayvalik cultivar), East (Memeli, Memecik, Domat and Gemlik cultivars), South (Memecik cultivar), Izmir Penisula (Erkence cultivar) and Firms (poly‐varietial oils or commercial blends). Consistent with discriminant analysis (DA), the predicted grouping in terms of the two harvest years were correctly separated as 84.6 and 85.9%, respectively. The highest levels of predicted grouping for the two harvest years were found in the North (Ayvalik cultivar) and Izmir peninsula (Erkence cultivar) groups (as 100%). In addition to oleic, linoleic, linolenic, margaric and margoleic acids, totaltransisomers of linoleic, linolenic and palmitic/linoleic were determined to be the best descriptive components for the oil samples.
La majorité des couples procréant par don de sperme envisagent d’informer l’enfant de son mode de conception, mais la plupart souhaitent le maintien de l’anonymat du donneur
Authors: Jouannet P. , Kunstmann J.-M. , Juillard J.-C. , Bresson J.-L. ,   La Fédération française des Cecos
Published: March 2010

L’anonymat du don de sperme est reconnu par la loi depuis 1994 en France, mais il a été supprimé par plusieurs pays. Nous présentons les résultats d’une étude qui a été réalisée dans 14 Cecos en 2006 auprès de 534 couples soit en phase d’attente ou en cours de réalisation de l’assistance médicale à la procréation, soit ayant déjà eu au moins un enfant par don de sperme. Les résultats sont très homogènes entre les hommes et les femmes et dans les différents groupes. Plus de 90 % des hommes et des femmes sont en accord avec l’anonymat du don de sperme, et moins de 10 % souhaitent que la loi change sur ce point. Environ un quart d’entre eux renoncerait à leur projet parental si la loi changeait. Plus de 50 % des couples envisagent d’informer l’enfant des modalités de sa conception. Près d’un tiers souhaiterait que des informations, concernant principalement la santé des donneurs, puissent leur être transmises ainsi qu’aux enfants. Les couples souhaitant devenir parents par don de sperme font une distinction claire entre l’anonymat du donneur et l’information de l’enfant sur les circonstances de sa conception.
En France, la majorité des donneurs de spermatozoïdes souhaite le maintien de leur anonymat
Authors: Kunstmann J.-M. , Jouannet P. , Juillard J.-C. , Bresson J.-L. ,   La Fédération française des Cecos
Published: March 2010

En France, l’anonymat du donneur de sperme, principe jusqu’alors jugé essentiel et qui avait été réaffirmé par deux fois dans les lois de bioéthique, se trouve aujourd’hui remis en question. Dans ce contexte, il est apparu utile aux Centres d’étude et de conservation des œufs et du sperme (Cecos) de connaître l’avis de ceux qui sont à l’origine de ces dons. En 2006, 193 donneurs de sperme recrutés dans 14 Cecos ont accepté de répondre anonymement à un questionnaire sur le sujet: 73 % étaient en accord avec le principe de l’anonymat, et moins de 30 % pensaient que la future législation devrait offrir aux enfants la possibilité de connaître l’identité du donneur. Si l’anonymat était levé, 60 % des hommes renonceraient à donner leur sperme. En revanche, la même proportion serait d’accord pour communiquer des informations non identifiantes les concernant aux parents et aux enfants.
Is low empathy related to bullying after controlling for individual and social background variables?
Authors: Jolliffe Darrick , Farrington David P.
Published: March 2010

This paper examines the relationship between low empathy and bullying while also controlling for the impact of a number of other individual and social background variables linked with bullying. This included the relationship to the prevalence of bullying, but also to the frequency and type of bullying. Questionnaires were completed by 720 adolescents (344 females, 376 males) aged 13–17 in three secondary schools in England. The results suggested that low affective empathy was independently related to bullying by males, but not females. There was no evidence that low cognitive empathy was independently related to bullying, but high impulsivity was related to all forms of male bullying and to female bullying. The implications of the findings for research and practice are discussed.