bluuebunny/crossref_metadata_2025 huggingface dataset:
Limiting behavior of MHD flow over a porous rotating disk with Hall currents
Authors: EL‐Mistikawy T.M.A. , El‐Fayez F.M.N.
Published: June 2013

An electrically conducting fluid is driven by a rotating disk, in the presence of a magnetic field that is strong enough to produce significant Hall currents. The disk is porous, allowing mass transfer through suction or injection. The limiting behavior of the flow is studied, as the magnetic field strength grows indefinitely. The flow variables are properly scaled, and uniformly valid asymptotic expansions of the velocity components are obtained through parameter straining. The leading order approximations show sinusoidal behavior that is decaying exponentially, as we move away from the disk surface. The two‐term expansions of the radial and azimuthal surface shear stress components, as well as the far field inflow speed, compare well with the corresponding finite difference solutions; even at moderate magnetic fields.
Numerical evidence for the validity of the NLS approximation in systems with a quasilinear quadratic nonlinearity
Authors: Chong C. , Schneider G.
Published: June 2013

The Nonlinear Schrödinger (NLS) equation is a universal amplitude equation which can be derived for the description of small spatio‐temporal modulations of an underlying carrier wave. The validity of this approximation for general dispersive wave systems possessing a quasilinear quadratic nonlinearity is an open problem that has remained unsolved for more than four decades. We report results on a systematic numerical simulation of such a quasilinear wave equation which strongly support the validity claim.
High precision modeling towards the 10‐20 level
Authors: Stephan E.P. , Andres M. , Banz L. , Costea A. , Nesemann L. , Lämmerzahl C. , Hackmann E. , Herrmann S. , Rievers B.
Published: June 2013

The requirements for accurate numerical simulations are increasing steadily. Modern high precision physics experiments now exceed the achievable numerical accuracy of standard commercial and scientific simulation tools. One example are optical resonators for which changes in the optical length are now commonly measured to 10‐15 precision. The achievable measurement accuracy for resonators and cavities is directly influenced by changes in the distances between the optical components. If deformations in the range of 10‐15 occur, those effects cannot be modeled and analyzed anymore with standard methods based on double precision data types. New experimental approaches point out that the achievable experimental accuracies may improve up to the level of 10‐17 in the near future. For the development and improvement of high precision resonators and the analysis of experimental data, new methods have to be developed which enable the needed level of simulation accuracy. Therefore we plan the development of new high precision algorithms for the simulation and modeling of thermo‐mechanical effects with an achievable accuracy of 10‐20. In this paper we analyze a test case and identify the problems on the way to this goal.
Analysis of a dynamic electro‐elastic problem
Authors: Barboteu M. , Kazmi K. , Sofonea M. , Han W.
Published: June 2013

We study a dynamic problem for linearly electro‐elastic materials, permitting piezoelectric effects. As a theoretical result, we state and prove the existence of a unique solution to the problem by using arguments of semi‐linear evolutionary equations and semigroups of linear continuous operators. Then we introduce a fully discrete scheme to solve the problem numerically. Under certain solution regularity assumptions, we derive an optimal order error estimate. Finally, we present some numerical results on a two‐dimensional test problem to illustrate the theoretical error estimate.
Large amplitude free vibration analysis of square plates resting on elastic foundation: A simple closed‐form solutions
Authors: Gunda J.B.
Published: June 2013

Large amplitude free vibration behavior of thin, isotropic square plate configurations resting on Winkler type of elastic foundation are expressed in the form of simple closed‐form solutions by using the Rayleigh‐Ritz (R‐R) method based on coupled displacement fields (CDF). Geometric non‐linearity of von‐Kármán type is taken into consideration. The in‐plane displacement field variations used in the formulation of the R‐R (CDF) method are derived by using the governing in‐plane static differential equations of the plate which in turn simplifies the difficulty of assuming an in‐plane displacement field variations of the plate. Accuracy and robustness of proposed closed‐form solutions is compared to the available finite element formulation results. Proposed closed‐form solutions are corrected for the simple harmonic motion (SHM) assumption using the well established harmonic balance method (HBM) which is applicable for the homogeneous form of cubic non‐linear Duffing equation.
Analytical length scale calibration of nonlocal continuum from a microstructured buckling model
Authors: Challamel N. , Lerbet J. , Wang C.M. , Zhang Z.
Published: June 2013

This paper deals with the buckling of a column which is modeled by some finite rigid segments and elastic rotational springs and relating its solution to continuum nonlocal elasticity. This problem, which can be referred to Hencky's chain, can serve as a basic model to rigorously investigate the effect of the microstructure on the buckling behaviour of a simple equivalent continuum structural model. The buckling problem of the pinned‐pinned discretized column is analytically investigated by introducing a Lagrange multiplier. Such a buckling problem is mathematically treated as an iterative eigenvalue problem. It is shown that the buckling load of this finite degree‐of‐freedom system is exactly obtained by a recursive formula involving Chebyschev polynomials. Euler's buckling load is asymptotically obtained at larger scales. However, at smaller scales, the buckling model highlights some scale effect that can be only captured by nonlocal elasticity for the equivalent continuum. We show that Eringen's nonlocal continuum is well suited to capture this scale effect. The small scale coefficient of the equivalent nonlocal continuum is then identified from the specific microstructure features, namely the length of each cell. It is shown that the small length scale coefficient valid for this buckling problem is very close to the one already identified from a comparison with the Born‐Kármán model of lattice dynamics using dispersive wave properties.
Spatial decay for several phase‐field models
Authors: Miranville A. , Quintanilla R.
Published: June 2013

In this paper, we study the spatial behavior of three phase‐field models. First, we consider the Cahn‐Hilliard equation and we obtain the exponential decay of solutions under suitable assumptions on the data. Then, for the classical isothermal phase‐field equation (i.e., the Allen‐Cahn equation), we prove the nonexistence and the fast decay of solutions and, for the nonisothermal case governed by the Fourier law, we obtain a Phragmén‐Lindelöf alternative of exponential type, respectively.
On the singular limit of a two‐phase flow equation with heterogeneities and dynamic capillary pressure
Authors: Kissling F. , Karlsen K.H.
Published: June 2013

We consider conservation laws with spatially discontinuous flux that are perturbed by diffusion and dispersion terms. These equations arise in a theory of two‐phase flow in porous media that includes rate‐dependent (dynamic) capillary pressure and spatial heterogeneities. We investigate the singular limit as the diffusion and dispersion parameters tend to zero, showing strong convergence towards a weak solution of the limit conservation law.
A note on stability of the vertical uniform rotations of the heavy top
Authors: Comănescu D.
Published: June 2013

We prove that the stability problem of a vertical uniform rotation of a heavy top is completely solved by using the linearization method and the conserved quantities of the differential system which describe the rotation of the heavy top.
Optimization of a singular flow in a porous medium
Authors: Beldiman M. , Boacă Ioana , Marinoschi G.
Published: June 2013

We address an optimization problem related to a diffusive flow in a nonhomogeneous porous medium. More exactly, the purpose is to control by a flow parameter an optimal average of the solution in a subset of the domain. The state model is degenerate and ill‐posed and this requires to develop a technique of optimization for a singular state system.
Enhanced functionally graded material shell finite elements
Authors: Kugler S. , Fotiu P.A. , Murin J.
Published: June 2013

Structures made of Functionally Graded Materials (FGMs) show a gradual variation of material properties in one, two, or three directions. In this paper, an efficient low‐order shell element with six nodal degrees of freedom (including the drill rotation) is presented, supplemented with a proper method for calculating effective elastic properties. This new FGM shell element can be coupled with 3D FGM beam elements on a single node. The numerical results indicate high effectiveness and accuracy of the proposed approach.
Concerning one approach to the reconstruction of heterogeneous residual stress in plate
Authors: Nedin R. , Vatulyan A.
Published: June 2013

In present paper the inverse problem on the identification of three non‐homogeneous residual stress components in rectangular plate in steady‐state vibration regime is considered. The equation building the iterative process of solving the inverse problem is formulated. An approach to the reconstruction of residual stresses is described on the basis of introduction the Airy prestress function. The technique of leading the inverse problem to a system of linear algebraic equations at each iteration is proposed. Results of conducting a series of computational experiments on the reconstruction are depicted and discussed.
Shape sensitivity analysis of Timoshenko's plate with a crack under the nonpenetration condition
Authors: Lazarev N.P. , Rudoy E.M.
Published: June 2013

An equilibrium problem for an elastic transversely isotropic Timoshenko's plate with a curvilinear crack is considered. On the crack faces, the nonpenetration conditions, which have the form of inequalities (conditions of the Signorini type), are given. By using a sufficiently smooth perturbation determined in the middle plate plane, the variation of plate geometry is specified. The formula of the derivative of the plate energy functional with respect to the perturbation parameter is deduced.
Equilibrium equations for transversely accreted shells
Authors: Lychev S.
Published: June 2013

A particular case of the theory of growing thin‐walled structures, namely the theory of transversely accreted shells is considered. A correspondence between equilibrium equations in terms of rates for transversally accreted shells and equilibrium equations in terms of displacements for permanent shells is established. The equilibrium equations for accreted shells that obey the kinematics hypothesis of Mindlin type are derived in terms of displacements as well as in terms of rates.
Free rate‐independent elastoplastic equations
Authors: Xiao H. , Bruhns O.T. , Meyers A.
Published: June 2013

New rate‐independent finite elastoplastic equations are proposed in unified forms applicable to all loading‐unloading cases. A departure from the classical elastoplastic equations is that these new equations are not subjected to and hence free from the usual extrinsic restrictive conditions, including the yield condition as well as the loading‐unloading conditions. Such free equations are of Eulerian rate type and assume the same smooth form for all possible stresses and for all strain rates. It is demonstrated that the essential representative features of finite elastoplastic deformations, namely, the yield behavior and the loading‐unloading behavior in the traditional sense, may be derived from and hence naturally incorporated as intrinsic physical characteristics into the free elastoplastic equations proposed in a more realistic sense and, in particular, the classical notions characterizing these features are found to exhibit novel, perhaps more profound physical meanings in the new equations. Furthermore, the strong discontinuity in tangent moduli at transition from elastic to plastic state, involved in the traditional formulation, is shown to be replaced by a smooth transition. Implications are discussed in respects of constitutive implications and numerical treatment.
Micromechanical and macromechanical modelling of foams: Identification of Cosserat parameters
Authors: Diebels S. , Geringer A.
Published: June 2013

The classical continuum model does not describe the mechanical behaviour of cellular materials. To model the size‐dependent mechanical properties of these materials, the extended continuum models such as the micropolar approach can be used. The reference data is extracted from the virtual experiments performed on an artificial open‐cell foam specimens. With the proper set of the Cosserat parameters the detailed microstructural model can be described on the macroscopic level using the extended continuum approach. The parameter identification task is defined as a minimisation task, which is solved using the evolutionary computational framework.
Propagation of linear compression waves through plane interfacial layers and mass adsorption in second gradient fluids
Authors: Rosi G. , Giorgio I. , Eremeyev V.A.
Published: June 2013

This paper addresses the problem of reflection and transmission of compression waves at the phase transition layer between the vapour and liquid phases of the same fluid. Within the framework of second gradient fluid modeling, we use a non‐convex free energy in order to describe the phase transition phenomenon. A stationary solution for the fluid density is found for an infinite domain, and an analytical expression for the phase transition is presented. Then the propagation of linear waves superposed to this stationary solution is discussed, with particular attention to the behaviour in correspondence of the interfacial layer. The reflection and transmission of waves is studied and analized with the aid of numerical simulations, and an interesting phenomenon of mass adsorption at the interface is observed and discussed.
Laparoscopy‐Assisted Distal Gastrectomy Versus Open Distal Gastrectomy. A Prospective Randomized Single‐Blind Study
Authors: Takiguchi Shuji , Fujiwara Yoshiyuki , Yamasaki Makoto , Miyata Hiroshi , Nakajima Kiyokazu , Sekimoto Mitsugu , Mori Masaki , Doki Yuichiro
Published: June 2013

Background

Laparoscopy‐assisted distal gastrectomy (LADG) is generally considered superior to open distal gastrectomy (ODG) with regard to postoperative quality‐of‐life. Differences in postoperative pain may exist due to recent pain control techniques including epidural anesthesia. There is little evidence for this difference. In this article we report the results of our randomized single‐blind study in LADG versus ODG. The aim of the present study was to evaluate differences in postoperative physical activity between LADG and ODG.

Methods

Forty patients with early gastric cancer (stage IA and IB) were registered in this randomized study. For strict evaluation, patients were not told about the type of operation until postoperative day 7. Postoperative physical activity was evaluated objectively by Active Tracer, which records the cumulative acceleration over a 24 h period to investigate differences in postoperative recovery. Questionnaire and visual analog scale score related to postoperative pain were also investigated.

Results

Significant differences were observed with a more favorable outcome noted in the LADG group with respect to intraoperative blood loss (P < 0.001), total amount of pain rescue (P < 0.001), wound size (P < 0.001), postoperative hospital stay (P < 0.001), and inflammatory parameters (C‐reactive protein, SaO2, and duration of febrile period) (P < 0.001). Cumulative physical recovery to 70 % of the preoperative level was significantly shorter (by 3 days, P < 0.001) in the LADG group.

Conclusions

Comparison of LADG and ODG for patients with early gastric cancer showed favorable outcome and earlier recovery of physical activity in the LADG group.
Diagnostics method for the rapid quantitative detection and identification of low-level contamination of high-purity water with pathogenic bacteria
Authors: Minogue Elizabeth , Reddington Kate , Dorai-Raj Siobhan , Tuite Nina , Clancy Eoin , Barry Thomas
Published: June 2013

High-purity water (HPW) can be contaminated with pathogenic microorganisms, which may result in human infection. Current culture-based techniques for the detection of microorganisms from HPW can be slow and laborious. The aim of this study was to develop a rapid method for the quantitative detection and identification of pathogenic bacteria causing low-level contamination of HPW. A novel internally controlled multiplex real-time PCR diagnostics assay was designed and optimized to specifically detect and identify Pseudomonas aeruginosa and the Burkholderia genus. Sterile HPW, spiked with a bacterial load ranging from 10 to 103 cfu/100 ml, was filtered and the bacterial cells were removed from the filters by sonication. Total genomic DNA was then purified from these bacteria and subjected to testing with the developed novel multiplex real-time PCR diagnostics assay. The specific P. aeruginosa and Burkholderia genus assays have an analytical sensitivity of 3.5 genome equivalents (GE) and 3.7 GE, respectively. This analysis demonstrated that it was possible to detect a spiked bacterial load of 1.06 × 102 cfu/100 ml for P. aeruginosa and 2.66 × 102 cfu/100 ml for B. cepacia from a 200-ml filtered HPW sample. The rapid diagnostics method described can reliably detect, identify, and quantify low-level contamination of HPW with P. aeruginosa and the Burkholderia genus in <4 h. We propose that this rapid diagnostics method could be applied to the pharmaceutical and clinical sectors to assure the safety and quality of HPW, medical devices, and patient-care equipment.
Idiopathic ventricular arrhythmia originating from the para‐Hisian area: Prevalence, electrocardiographic and electrophysiological characteristics
Authors: Ban Ji‐Eun , Chen Yung‐Lung , Park Hwan‐Cheol , Kim Dong‐Hyeok , Lee Dae‐In , Park Yae‐Min , Choi Jong‐Il , Lim Hong‐Euy , Park Sang‐Weon , Kim Young‐Hoon
Published: June 2013

Background

We investigated the prevalence and the electrocardiographic and electrophysiological characteristics of ventricular arrhythmias (VAs) originating from the para‐Hisian area.

Methods

Among 250 patients with idiopathic VAs, 8 (3.2%) had an ablation site in the para‐Hisian region. For comparison with right ventricular (RV) para‐Hisian VAs (n=6), 27 patients with VAs originating from the posterior RV outflow tract (RVOT) were studied.

Results

Para‐Hisian VAs had an R wave in leads I and aVL. The VAs originating from the site below the His bundle region were determined to have a superior axis (n=4, 50%). A His potential was recorded at the proximal bipole of the successful ablation site in 6 patients. RV para‐Hisian VAs had a narrower QRS width (114±12 ms vs. 139±12 ms, P=0.003), as well as a higher incidence of R waves in lead aVL (83.3% vs. 0%, P<0.001) and QS waves in lead V1 (83.3% vs. 22.2%, P=0.004) compared to posterior RVOT VAs. A greater R wave amplitude in lead I (1.15±0.34 mV vs. 0.34±0.18 mV, P=0.001) and a smaller R wave amplitude in the inferior leads (0.68±0.23 mV vs. 1.58±0.55 mV, P<0.001), with a higher R wave amplitude ratio in leads II/III (4.2±2.0 vs. 1.1±0.2, P=0.01) were the major ECG characteristics.

Conclusions

Para‐Hisian VAs have distinctive electrocardiographic features and can be successfully eliminated without disturbance of atrioventricular conduction.
Rescue or Return: The Fate of the Iraqi Jewish Archive
Authors: Montgomery Bruce P.
Published: June 2013

Shortly following the 2003 invasion of Iraq, an American mobile exploitation team was diverted from its mission in hunting for weapons for mass destruction to search for an ancient Talmud in the basement of Saddam Hussein's secret police (Mukhabarat) headquarters in Baghdad. Instead of finding the ancient holy book, the soldiers rescued from the basement flooded with several feet of fetid water an invaluable archive of disparate individual and communal documents and books relating to one of the most ancient Jewish communities in the world. The seizure of Jewish cultural materials by the Mukhabarat recalled similar looting by the Nazis during World War II. The materials were spirited out of Iraq to the United States with a vague assurance of their return after being restored. Several years after their arrival in the United States for conservation, the Iraqi Jewish archive has become contested cultural property between Jewish groups and the Iraqi Jewish diaspora on the one hand and Iraqi cultural officials on the other. This article argues that the archive comprises the cultural property and heritage of the Iraqi Jewish diaspora.
Improving shift-reduce constituency parsing with large-scale unlabeled data
Authors: ZHU MUHUA , ZHU JINGBO , WANG HUIZHEN
Published: June 2013

Shift-reduce parsing has been studied extensively for diverse grammars due to the simplicity and running efficiency. However, in the field of constituency parsing, shift-reduce parsers lag behind state-of-the-art parsers. In this paper we propose a semi-supervised approach for advancing shift-reduce constituency parsing. First, we apply the uptraining approach (Petrov, S. et al. 2010. In Proceedings of the 2010 Conference on Empirical Methods in Natural Language Processing (EMNLP), Cambridge, MA, USA, pp. 705–713) to improve part-of-speech taggers to provide better part-of-speech tags to subsequent shift-reduce parsers. Second, we enhance shift-reduce parsing models with novel features that are defined on lexical dependency information. Both stages depend on the use of large-scale unlabeled data. Experimental results show that the approach achieves overall improvements of 1.5 percent and 2.1 percent on English and Chinese data respectively. Moreover, the final parsing accuracies reach 90.9 percent and 82.2 percent respectively, which are comparable with the accuracy of state-of-the-art parsers.
The dosimetric impact of supplementing pre-planned prostate implants with discretionary 125I seeds
Authors: McParland Neil , Chng Nicholas , Keyes Mira
Published: June 2013

Introduction

Prostate implants at the British Columbia Cancer Agency are performed using a pre-planned technique. Physicians can augment the dose distribution using one to five non-planned ‘extra’ seeds and this option is determined without intraoperative feedback. The purpose of this research is to quantify the dosimetric impact of extra seeds and to assess the circumstances under which they are considered necessary.

Materials and methods

Implanting physicians used a questionnaire to record the three-dimensional location and their rationale for using extra seeds. A plan reconstruction algorithm was used to distinguish the extra seeds from the planned seeds. Distributions with and without extra seeds were calculated to quantify the dosimetric impact to the prostate, urethra and rectum.

Results

Extra seeds resulted in mean relative increases to V100, V150 and V200 of 3·7%, 13% and 19·1%, respectively. Mean prostate D90 increased from 147 to 156 Gy. Improvements in post-implant quality assurance codes were recorded in 30% of the implants with minimal dose increase to the rectum and urethra. Extra seeds were mainly deposited in the prostate anterior–superior quadrant.

Conclusions

The use of two to five extra seeds can result in improvements to pre-planned prostate implants, whereas the costs in terms of increased rectal and prostatic urethral dose are relatively minor.
Direct microwave-assisted amino acid synthesis by reaction of succinic acid and ammonia in the presence of magnetite
Authors: Jiang Nan , Liu Dandan , Shi Weiguang , Hua Yingjie , Wang Chongtai , Liu Xiaoyang
Published: June 2013

Since the discovery of submarine hot vents in the late 1970s, it has been postulated that submarine hydrothermal environments would be suitable for emergence of life on Earth. To simulate warm spring conditions, we designed a series of microwave-assisted amino acid synthesis involving direct reactions between succinic acid and ammonia in the presence of the magnetite catalyst. These reactions which generated aspartic acid and glycine were carried out under mild temperatures and pressures (90–180 °C, 4–19 bar). We studied this specific reaction inasmuch as succinic acid and ammonia were traditionally identified as prebiotic compounds in primitive deep-sea hydrothermal systems on Earth. The experimental results were discussed in both biochemical and geochemical context to offer a possible route for abiotic amino acid synthesis. With extremely diluted starting materials (0.002 M carboxylic acid and 0.002 M ammonia) and catalyst loading, an obvious temperature dependency was observed in both cases [neither product was detected at 90 °C in comparison with 21.08 μmol L−1 (aspartic acid) and 70.25 umol L−1 (glycine) in 180 °C]. However, an opposite trend presented for reaction time factor, namely a positive correlation for glycine, but a negative one for aspartic acid.
The Influence of Differential Focus on the Endowment Effect in Risky Objects
Authors: Kleber Janet , Dickert Stephan , Betsch Tilmann
Published: June 2013

The robust finding that people systematically assign higher monetary values to sell a good they own than they pay to acquire it (i.e., the endowment effect) was recently explained by the differential importance of positive and negative object properties, depending on endowment state. Whether this explanation can also be applied to objects with risky outcomes is not clear. Two studies using lottery tickets were designed to examine the effects of focusing on aspects consistent with a person’s endowment state (i.e., probability of winning and size of winnings for owners; probability of losing and price of lottery ticket for nonowners) or inconsistent with it. In line with previous research on consumer products, both studies showed an endowment effect for lottery tickets when participants focused on consistent aspects, but not when they focused on inconsistent aspects. We conclude that, although price decisions are mainly influenced by endowment state, the underlying focus on specific properties likely plays a role in the endowment effect for risky objects.
Die Erfassung von Verhaltensauffälligkeiten im Vorschulalter mit dem Elternfragebogen für Klein- und Vorschulkinder (CBCL/11/2 – 5)
Authors: Plück Julia , Beiling Michèle , Hautmann Christopher , Kuschel Annett , Heinrichs Nina , Schmeck Klaus , Döpfner Manfred
Published: June 2013

Der Elternfragebogen für Klein- und Vorschulkinder CBCL/11/2 – 5, die Übersetzung des englischsprachigen Originals aus der Fragebogenfamilie von Thomas Achenbach, wird anhand von Daten aus dem deutschsprachigen Raum hinsichtlich seiner Anwendbarkeit überprüft. Diese umfasst die Überprüfung der faktoriellen Struktur, der internen Konsistenzen der Skalen und ihrer Korrelationen untereinander sowie Mittelwertvergleiche verschiedener Teilstichproben. Die Ergebnisse lassen die Anwendung des Fragebogens für gruppenstatistische Analysen im Rahmen verschiedener Forschungsfragestellungen gerechtfertigt scheinen. Die übergeordneten Dimensionen Externales Problem und Internales Problem sowie die Problemskalen Aufmerksamkeitsprobleme und Aggressives Verhalten können auch in der klinischen Einzelfalldiagnostik zuverlässig eingesetzt werden.
Eignung des Kurzfragebogens IRES-24 zur Evaluation gesundheitlicher Präventionsmaßnahmen
Authors: Meffert Cornelia , Gerdes Nikolaus
Published: June 2013

Im vorliegenden Beitrag wird der Einsatz des Kurzfragebogens IRES-24 im Kontext gesundheitlicher Präventionsmaßnahmen psychometrisch analysiert. Folgende Testgütekriterien wurden überprüft: Akzeptanz, Werteverteilung, interne Konsistenz, faktorielle Struktur und Änderungssensitivität. Ferner wurde anhand der Bildung von Verlaufstypen der Zusammenhang zwischen Gewichtsreduktion und einer Veränderung der gesundheitsbezogenen Lebensqualität untersucht. Der IRES-24 wurde zu fünf Messzeitpunkten N = 851 Teilnehmern an einem kommerziellen Gewichtsreduktionsprogramm vorgelegt. Der geringe Anteil fehlender Werte (1.2 %) lässt auf eine hohe Akzeptanz der Items des IRES-24 schließen. Alle Skalen erwiesen sich als intern konsistent. Die SRM-Effektstärken lagen zur Jahreskatamnese für die Dimensionen des IRES-24 zwischen 0.55 und 0.97. Bei der Bildung von Verlaufstypen zeigte sich ein signifikanter Zusammenhang zwischen einer erfolgreichen Gewichtsreduktion und einer Verbesserung der gesundheitsbezogenen Lebensqualität. Auf der Basis der vorgelegten Ergebnisse kann der IRES-24 zur Messung der gesundheitsbezogenen Lebensqualität im Kontext gesundheitlicher Präventionsmaßnahmen empfohlen werden.
Entwicklung und Validierung einer ultrakurzen Operationalisierung des Konstrukts Optimismus-Pessimismus
Authors: Kemper Christoph J. , Beierlein Constanze , Kovaleva Anastassiya , Rammstedt Beatrice
Published: June 2013

Das Konstrukt Optimismus-Pessimismus ist aufgrund seiner vielfältigen Beziehungen zu gesellschaftlich relevanten Prozessen und Phänomen nicht nur für Psychologen, sondern auch für Forscher anderer Disziplinen von Interesse, zum Beispiel für Sozialwissenschaftler, Ökonomen und Gesundheitsforscher. In deren Untersuchungen sind aufgrund starker monetärer Restriktionen insbesondere ökonomische Operationalisierungen gefragt. Auf der Grundlage der weit verbreiteten Konstruktdefintion von Scheier und Carver (1985) , Optimismus-Pessimismus als generalisierte Erwartungen zukünftiger Ereignisse, wurde eine ökonomische Skala mit zwei Items entwickelt (Skala Optimismus-Pessimismus-2, SOP2). Die Formulierungen wurden in einem kognitiven Prestest für die anvisierte Zielgruppe, die deutschsprachige Bevölkerung, optimiert und anschließend in zwei umfangreichen heterogenen Stichproben validiert: einer Quotenstichprobe (N = 539) und einer Zufallsstichprobe (N = 1 134). Verschiedene Aspekte der psychometrischen Güte wurden geprüft. Die berichteten Befunde sprechen für die Reliabilität und Konstruktvalidität der SOP2. Auch mit der entwickelten ultrakurzen Operationalisierung ist es möglich die aus der Literatur bekannten Beziehungen im nomologischen Netzwerk des Konstrukts Optimismus-Pessimismus adäquat abzubilden.
Wann und wie lernen Teams?
Authors: Oertel Rasmus , Antoni Conny H.
Published: June 2013

Dieser Artikel entwickelt ein integratives und multidimensionales Konzept von Teamlernen, das Teamlernprozesse (z. B. Edmondson, 1999 ) in ein Phasenmodell von Teamprozessen (z. B. Marks, Mathieu & Zaccaro, 2001 ) einordnet und unterbrechende Ereignisse ( Zellmer-Bruhn, 2003 ) als situative Auslöser von Teamlernen berücksichtigt. Ausgehend von diesen theoretischen Überlegungen werden Fragestellungen für zukünftige Forschungsarbeiten abgeleitet und forschungspraktische Implikationen diskutiert.
Youth and New Media
Authors: Blumberg Fran C. , Blades Mark , Oates Caroline
Published: June 2013

The prevalence of digital media use among children and adolescents is indisputable. One medium to which children and adolescents dedicate a sizeable portion of their time is that of the digital game. Accordingly, digital game play continues to grow as a context for cognitive development. We showcase new research and practice addressing the impact of this very popular activity on children’s and adolescents’ learning. Our goal is to stimulate new research and interest in examining the positive ramifications of digital play for development among today’s youth.
Formative Research for STEM Educational Games
Authors: Sherry John L.
Published: June 2013

Millions in taxpayer and foundation euros and dollars have been spent building and testing educational video games, games for health, and serious games. What have been the fruits of this frenzy of activity? What educational video game has had the reach and impact of Sesame Street or Blues Clues television shows? By comparison, the Children’s Television Workshop (CTW) managed to get Sesame Street off the ground within a couple of years, writing the basic scientific literature on educational media design in the process. Not only is Sesame Street well known and proven, it laid the basis for every effective educational show to follow. This article explores the differences between the CTW scientific approach to educational media production and the mostly nonscientific approach consuming so many resources in the educational games, games for health, and serious games movements. Fundamental scientific questions that remain unanswered are outlined.
Exergaming in Youth
Authors: Best John R.
Published: June 2013

Exergaming (a portmanteau of “exercise” and “gaming”) is a relatively new genre of interactive video gaming that stimulates an active, whole-body gaming experience. Exergaming could have a significant positive impact on youth as across the globe youth are living more sedentary lifestyles. Exergaming has the potential to thwart this trend by engaging youth in physical activity (PA). Exergaming is not only physically-engaging but is also cognitively-engaging, and this combination of physical and cognitive engagement may translate into improved cognitive function in youth. The purpose of this review article is to examine the state-of-the-art in exergaming research to address whether exergames are a viable tool to promote PA in youth and benefit cognitive functioning among youth. The research addressing these questions is still quite nascent; therefore, only tentative conclusions can be drawn. However, this review points out promising lines of research and makes suggestions for future research to obtain more firm conclusions.
Concomitant Analysis of Arterial, Venous, and CSF Flows using Phase-Contrast MRI: A Quantitative Comparison Between MS Patients and Healthy Controls
Authors: ElSankari Souraya , Balédent Olivier , van Pesch Vincent , Sindic Christian , de Broqueville Quentin , Duprez Thierry
Published: June 2013

Venous dysfunction has recently been hypothesized to contribute to the pathophysiology of multiple sclerosis (MS). 2D phase-contrast (PC) magnetic resonance imaging (MRI) is a non-invasive and innocuous technique enabling reliable quantification of cerebrospinal fluid (CSF) and blood flows in the same imaging session. We compared PC-MRI measurements of CSF, arterial and venous flows in MS patients to those from a normative cohort of healthy controls (HC). Nineteen MS patients underwent a standardized MR protocol for cerebral examination on a 3T system including Fast cine PC-MRI sequences with peripheral gating in four acquisition planes. Quantitative data were processed using a homemade software to extract CSF and blood flow regions of interest, animate flows, and calculate cervical and intracranial vascular flow curves during the cardiac cycle (CC). Results were compared with values obtained in 21 HC using multivariate analysis. Venous flow patterns were comparable in both groups without signs of reflux. Arterial flows ( P = 0.02) and cervical CSF dynamic oscillations ( P = 0.01) were decreased in MS patients. No significant differences in venous cerebral and cervical outflows were observed between groups, thereby contradicting the recently proposed theory of venous insufficiency. Unexpected decrease in arterial perfusion in MS patients warrants further correlation to volumetric measurements of the brain.
Three-dimensional deep sub-diffraction optical beam lithography with 9 nm feature size
Authors: Gan Zongsong , Cao Yaoyu , Evans Richard A. , Gu Min
Published: June 2013

The current nanofabrication techniques including electron beam lithography provide fabrication resolution in the nanometre range. The major limitation of these techniques is their incapability of arbitrary three-dimensional nanofabrication. This has stimulated the rapid development of far-field three-dimensional optical beam lithography where a laser beam is focused for maskless direct writing. However, the diffraction nature of light is a barrier for achieving nanometre feature and resolution in optical beam lithography. Here we report on three-dimensional optical beam lithography with 9 nm feature size and 52 nm two-line resolution in a newly developed two-photon absorption resin with high mechanical strength. The revealed dependence of the feature size and the two-line resolution confirms that they can reach deep sub-diffraction scale but are limited by the mechanical strength of the new resin. Our result has paved the way towards portable three-dimensional maskless laser direct writing with resolution fully comparable to electron beam lithography.
Enhancement of Vibronic and Ground-State Vibrational Coherences in 2D Spectra of Photosynthetic Complexes
Authors: Chenu Aurélia , Christensson Niklas , Kauffmann Harald F. , Mančal Tomáš
Published: June 2013

A vibronic-exciton model is applied to investigate the recently proposed mechanism of enhancement of coherent oscillations due to mixing of electronic and nuclear degrees of freedom. We study a dimer system to elucidate the role of resonance coupling, site energies, vibrational frequency and energy disorder in the enhancement of vibronic-exciton and ground-state vibrational coherences and to identify regimes where this enhancement is significant. For a heterodimer representing two coupled bachteriochloropylls of the FMO complex, long-lived vibronic coherences are found to be generated only when the frequency of the mode is in the vicinity of the electronic energy difference. Although the vibronic-exciton coherences exhibit a larger initial amplitude compared to the ground-state vibrational coherences, we conclude that, due to the dephasing of the former, both type of coherences have a similar magnitude at longer population time.
A GPI anchor explains the unique biological features of the common NKG2D-ligand allele MICA*008
Authors: Ashiru Omodele , López-Cobo Sheila , Fernández-Messina Lola , Pontes-Quero Samuel , Pandolfi Rachele , Reyburn Hugh T. , Valés-Gómez Mar
Published: June 2013

The human MICA (MHC I-related chain A) gene, encoding a ligand for the NKG2D (NKG2-D type II integral membrane protein) receptor, is highly polymorphic. A group of MICA alleles, named MICA 5.1 (prototype, MICA*008), produce a truncated protein due to a nucleotide insertion in the transmembrane domain. These alleles are very frequent in all of the human populations studied and they have different biological properties, compared with full-length alleles, e.g. recruitment into exosomes, which makes them very potent for down-modulating the NKG2D receptor in effector immune cells. Moreover, MICA*008 is not affected by viral immune evasion mechanisms that target other MICA alleles. In the present study, we demonstrate that MICA*008 acquires a GPI (glycosylphosphatidylinositol) anchor and that this modification is responsible for many of the distinct biological features of the truncated MICA alleles, including recruitment of the protein to exosomes. MICA*008 processing is also unusual as it is observed in the endoplasmic reticulum as a Triton™ X-114 soluble protein, partially undergoing GPI modification while the rest is exocytosed, suggesting a new model for MICA*008 release. This is the first report of a GPI-anchored MICA allele. The finding that this modification occurs in both families of human NKG2D ligands, as well as in the murine system, suggests positive pressure to maintain this biochemical feature.
ROS inhibitor N-acetyl-L-cysteine antagonizes the activity of proteasome inhibitors
Authors: Halasi Marianna , Wang Ming , Chavan Tanmay S. , Gaponenko Vadim , Hay Nissim , Gartel Andrei L.
Published: June 2013

NAC (N-acetyl-L-cysteine) is commonly used to identify and test ROS (reactive oxygen species) inducers, and to inhibit ROS. In the present study, we identified inhibition of proteasome inhibitors as a novel activity of NAC. Both NAC and catalase, another known scavenger of ROS, similarly inhibited ROS levels and apoptosis associated with H2O2. However, only NAC, and not catalase or another ROS scavenger Trolox, was able to prevent effects linked to proteasome inhibition, such as protein stabilization, apoptosis and accumulation of ubiquitin conjugates. These observations suggest that NAC has a dual activity as an inhibitor of ROS and proteasome inhibitors. Recently, NAC was used as a ROS inhibitor to functionally characterize a novel anticancer compound, piperlongumine, leading to its description as a ROS inducer. In contrast, our own experiments showed that this compound depicts features of proteasome inhibitors including suppression of FOXM1 (Forkhead box protein M1), stabilization of cellular proteins, induction of ROS-independent apoptosis and enhanced accumulation of ubiquitin conjugates. In addition, NAC, but not catalase or Trolox, interfered with the activity of piperlongumine, further supporting that piperlongumine is a proteasome inhibitor. Most importantly, we showed that NAC, but not other ROS scavengers, directly binds to proteasome inhibitors. To our knowledge, NAC is the first known compound that directly interacts with and antagonizes the activity of proteasome inhibitors. Taken together, the findings of the present study suggest that, as a result of the dual nature of NAC, data interpretation might not be straightforward when NAC is utilized as an antioxidant to demonstrate ROS involvement in drug-induced apoptosis.
Kinetic study on lipase catalyzed trans-esterification of palm oil and dimethyl carbonate for biodiesel production
Authors: Sun Shuzhen , Zhang Liping , Meng Xin , Xin Zhong
Published: June 2013

Kinetics of the trans-esterification of palm oil and dimethyl carbonate (DMC) for biodiesel production has been studied at the catalysis of immobilized lipase Novozyme 435. The relationship between initial reaction rate and temperature was established and the activation energy (Ea) was obtained first, based on the Arrhenius law. The value of Ea was 26.0 kJ/mol. The external diffusion limitation was neglected by raising the agitation speed to 200 rpm. And the influence of internal mass transfer limitations could also be neglected due to the linear relationship between the initial reaction rate and enzyme concentration. The effect of the concentration of palm oil was studied over the range of 30–700 mmol/l by keeping the catalyst amount constant. No substrate inhibition was observed under above experiment conditions. Therefore, the model based on a Ping-Pong bi-bi mechanism without substrate inhibition was proposed to describe the trans-esterification kinetics. The simulated values calculated by matlab could fit the experimental values quite well, indicating the trans-esterification kinetics of palm oil and DMC agrees with the ordered bi-bi mechanism.
Performance improvement of Ge-Sb-Te material by GaSb doping for phase change memory
Authors: Lu Yegang , Zhang Zhonghua , Song Sannian , Shen Xiang , Wang Guoxiang , Cheng Limin , Dai Shixun , Song Zhitang
Published: June 2013

Effects of GaSb doping on phase change characteristics of Ge-Sb-Te material are investigated by in situ resistance and x-ray diffraction measurement, optical spectroscopy, and x-ray photoelectron spectroscopy. The crystallization temperature and data retention of Ge-Sb-Te material increase significantly by the addition of GaSb, which results from the high thermal stability of amorphous GaSb. In addition, GaSb-doped Ge-Sb-Te material exhibits faster crystallization speed due to the change in electronic states as a result of the formation of chemical bonds with Ga element. Incorporation of GaSb is highly effective way to enhance the comprehensive performance of Ge-Sb-Te material for phase change memory.
Critical asymmetry in renormalization group theory for fluids
Authors: Zhao Wei , Wu Liang , Wang Long , Li Liyan , Cai Jun
Published: June 2013

The renormalization-group (RG) approaches for fluids are employed to investigate critical asymmetry of vapour-liquid equilibrium (VLE) of fluids. Three different approaches based on RG theory for fluids are reviewed and compared. RG approaches are applied to various fluid systems: hard-core square-well fluids of variable ranges, hard-core Yukawa fluids, and square-well dimer fluids and modelling VLE of n-alkane molecules. Phase diagrams of simple model fluids and alkanes described by RG approaches are analyzed to assess the capability of describing the VLE critical asymmetry which is suggested in complete scaling theory. Results of thermodynamic properties obtained by RG theory for fluids agree with the simulation and experimental data. Coexistence diameters, which are smaller than the critical densities, are found in the RG descriptions of critical asymmetries of several fluids. Our calculation and analysis show that the approach coupling local free energy with White's RG iteration which aims to incorporate density fluctuations into free energy is not adequate for VLE critical asymmetry due to the inadequate order parameter and the local free energy functional used in the partition function.
Dependence between velocity slip and temperature jump in shear flows
Authors: Sun Jie , Wang Wen , Wang Hua Sheng
Published: June 2013

In this paper, we investigate the dependence of coupled velocity slip (quantified by the slip length) and temperature jump (quantified by the Kapitza length) on solid-liquid bonding strength and shear rate in shear flows. We find that the interfacial behaviors of nano-confined liquid are distinctly different in the weak and strong solid-liquid interaction regimes identified by a threshold of β = 2 (β being the proportional factor of solid-liquid bonding strength). In the weak solid-liquid interaction regime, the liquid molecules adjacent to the surface of the wall are randomly distributed and are free to slip. The variations of the slip and Kapitza lengths against solid-liquid bonding strength and shear rate are regular and monotonic. In the strong solid-liquid interaction regime, the liquid molecules in the vicinity of the wall are in multi-layered ordering and are largely restricted. The slip length becomes multivalued with increasing solid-liquid bonding strength and shear rate, while the Kapitza length seems insensitive to these two parameters. Furthermore, we find that (1) the temperature jump monotonically increases with velocity slip in the weak solid-liquid interaction regime, while it varies non-monotonically with a minimum value in the strong solid-liquid interaction regime; (2) the Kapitza length grows as a power function of the slip length in the weak solid-liquid interaction regime, while it keeps constant in the strong solid-liquid interaction regime.
Accurate structure, thermodynamics, and spectroscopy of medium-sized radicals by hybrid coupled cluster/density functional theory approaches: The case of phenyl radical
Authors: Barone Vincenzo , Biczysko Malgorzata , Bloino Julien , Egidi Franco , Puzzarini Cristina
Published: June 2013

The coupled-cluster singles doubles model with perturbative treatment of triples (CCSD(T)) coupled with extrapolation to the complete basis-set limit and additive approaches represent the “golden standard” for the structural and spectroscopic characterization of building blocks of biomolecules and nanosystems. However, when open-shell systems are considered, additional problems related to both specific computational difficulties and the need of obtaining spin-dependent properties appear. In this contribution, we present a comprehensive study of the molecular structure and spectroscopic (IR, Raman, EPR) properties of the phenyl radical with the aim of validating an accurate computational protocol able to deal with conjugated open-shell species. We succeeded in obtaining reliable and accurate results, thus confirming and, partly, extending the available experimental data. The main issue to be pointed out is the need of going beyond the CCSD(T) level by including a full treatment of triple excitations in order to fulfil the accuracy requirements. On the other hand, the reliability of density functional theory in properly treating open-shell systems has been further confirmed.