bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of a Grid‐Free Kinetic Model to the Collisionless Sheath
Authors: Matyash K. , Schneider R. , Sydora R. , Taccogna F.
Published: March 2008

In this work we present a grid‐free hierarchical treecode, developed for simulation of bounded plasmas. The code follows both electrons and ions dynamics, resolving 1 spatial and 3 velocity coordinates. The code was applied for the simulation of a magnetized collisionless plasma in front of a material wall. The results obtained are in very good agreement with those of Particle‐in‐Cell simulation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gyrokinetic Approach to the Analysis of Incident Angle Distribution of Ions in a Magnetized Sheath
Authors: Kawamura G. , Fukuyama A.
Published: March 2008

The distribution of incident angle of ions to the wall surface in a magnetized plasma is studied by using a gyrokinetic model equation and a full‐kinetic particle‐in‐cell simulation code. The model equation is based on the gyrokinetic energy conservation of a plasma with a strong electric field. The dependence of the angular distribution on the magnetic field angle derived from the model equation and the result of particle simulation agree well when the ion thermal Larmor radius is comparable or less than the Debye length. The energy‐fluxweighted averages of the incident angles for various magnetic field strength are studied by using the particle simulation. Reduction of the average angle is observed for weaker magnetic field. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Neutral Transport Analysis in a Non‐Axisymmetric Plasma Confining System Based on a Monte‐Carlo Simulation
Authors: Nakashima Y. , Higashizono Y. , Kobayashi S. , Yabutani H. , Shoji M. , Mizuuchi T. , Nagasaki K. , Okada H. , Sano F. , Kondo K. , Kawano H. , Cho T.
Published: March 2008

Transport of neutral particles in a non‐axisymmetric plasma device is described based on a Monte‐Carlo simulation and of Dα line‐emission measurements. DEGAS three‐dimensional (3‐D) Monte‐Carlo code for neutral transport simulation has been applied to a helical‐axis heliotron device, Heliotron J. In a whole area of Heliotron J vacuum vessel, a detailed 3‐D mesh structure for the simulation was constructed especially for the precise investigation of particle transport in the toroidal direction. In this mesh model, a carbon target is also modeled in the simulation space, and the simulation has been carried out for the target insertion experiments in Heliotron J. Simulation results were compared with the results obtained from two‐dimensional image captured with a CCD camera viewing the top surface of the carbon target. The compared results indicated that the particle source caused by the carbon target is thought to be much more localized than expected one from the Dα image around the target. Particle transport to the toroidal direction was also discussed based on the 3‐D simulation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of the Detachment under the Influence of the Supersonic Flow in the Divertor Region
Authors: Marchuk O. , Tokar M. Z.
Published: March 2008

It is demonstrated in the framework of a one‐dimensional model for the scrape‐off layer that with increasing upstream plasma density and decreasing temperature near divertor target plates a supersonic flow develops in the front of the target. This flow is an important mechanism for the transition from high‐recycling regime to a weak detached state and has a significant impact on the plasma parameters, in particular, the pressure and particle flux to the plates, after detachment. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of SOL Decay Length on Modeling of Divertor Detachment by Using Simple Core‐SOL‐Divertor Model
Authors: Hiwatari R. , Hatayama A. , Takizuka T.
Published: March 2008

Taken impurity radiation and momentum loss in the divertor region into consideration, the applicability of Core‐SOL‐Divertor(CSD) model to the divertor detachment is investigated. Three solutions for the low recycling state, the high recycling state and the detached state can be obtained from the CSD model. The dependence of the ratio of the decay length for the density (Δn ) and temperature (ΔT ) in the SOL region is also examined, and it is found that Δn /ΔT ∼ T0.5s scaled by the SOL temperature (Ts), which is based on the experimental data, has a good potential to reproduce B2‐EIRENE results. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimization of Closed Divertor Configuration for Effective Particle Control in LHD Plasmas
Authors: Shoji M. , Kobayashi M. , Masuzaki S. , Watanabe T. , Iwamae A. , Yamada H. , Komori A. , LHD Experimental Groups
Published: March 2008

Neutral particles in the LHD plasma periphery are investigated by three‐dimensional neutral particle transport simulation. The simulation predicts significant change of the density profile of neutral particles depending on magnetic configurations (radial position of the magnetic axis Rax ). The polarization resolved Hα spectra and the Hα intensity profile measured in the three different magnetic configurations are consistent with calculations by the simulation. It shows that the density of neutral hydrogen molecules in the inboard side of torus is relatively high in magnetic configurations (3.50m < Rax < 3.75m), which also indicates that enhancement of the neutral density by more than one order of magnitude is necessary for effective particle control in LHD plasmas. The simulation strongly suggests that installation of closed divertor components in the inboard side is reasonable. The simulation coupled with a one‐dimensional plasma fluid analysis on divertor legs proposes an optimized closed divertor configuration which can enhance the neural density in the inboard side of the torus. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Implementation of a Toroidal Limiter Model into the Gyrokinetic Code ELMFIRE
Authors: Leerink S. , Heikkinen J. A. , Janhunen S. J. , Kiviniemi T. P. , Nora M. , Ogando F.
Published: March 2008

The ELMFIRE full f nonlinear gyrokinetic simulation code has been developed for calculations of plasma evolution and dynamics of turbulence in tokamak geometry. The code is applicable for calculations of strong perturbations in particle distribution function, rapid transients and steep gradients in plasma. Benchmarking against experimental reflectometry data from the FT2 tokamak [1,2,3] is being discussed and in this paper a model for comparison and studying poloidal velocity is presented. To make the ELMFIRE code suitable for scrape of layer simulations a simplified toroidal limiter model has been implemented. The model will be discussed and first results are presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reduced Models of Impurity Seeded Edge Plasmas
Authors: Morozov D. Kh.
Published: March 2008

The reduced descriptions of the distribution of impurities over ionization states, radiation losses and plasma dynamics are reviewed. Two and three most important ion approximation for light impurities and continuous descriptions of heavy impurities are discussed. Reduced descriptions of atomic processes like ionization, photo‐ and dielectronic recombination rates as well as of radiation abilities are proposed. As it shown, thermal forces, final relaxation times of impurity distributions over ionization states, charge‐exchange and opacity effects must be taken into account in reduced models, especially for ITER problems. Linear and nonlinear stages of the radiation‐condensation mode as well as some aspects of disruptions and noble gas injection into tokamak plasmas are analyzed with the reduced models. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fluctuating Helium Emission in Optically Thick Divertor Plasmas
Authors: Rosmej F. B. , Ohno N. , Takamura S. , Kajita S.
Published: March 2008

Simulations of the helium radiative properties carried out with the recently developed multi‐level meta‐stable resolved collisional‐radiative code SOPHIA discovered new unique emission lines to analyze optically thick divertor plasmas relevant for ITER. The comparison of their time dependent line emission obtained from the NAGDIS‐II plasma simulator experiments with time dependent temperature probe measurements shows a strong correlation. This indicates that line intensity fluctuations can be transformed to the important quantities of density and temperature fluctuations. A transformation method based on integral line intensity ratios which can be recorded with high time resolution is discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulating the Role of Intrinsic Carbon Impurities in the Divertor Detachment of ASDEX Upgrade
Authors: Wischmeier M. , Bonnin X. , Coster D. P. , Chankin A. V. , Kallenbach A. , Müller H. W. , ASDEX Upgrade Team
Published: March 2008

As part of a general effort in validating SOL fluid Monte Carlo codes, well diagnosed ohmic discharges have been done in ASDEX Upgrade reaching from the lowest accessible density up to densities at which both targets were at least partially detached. The numerical code B2.5‐EIRENE has been used to simulate these experiments with a particular focus on detachment. Whilst it is possible to qualitatively reproduce the general experimental observations when transiting from attached to detached plasmas, the simulations do not reproduce the detachment threshold observed in experiment quantitatively. The strong asymmetry of the ion flux density between the inner and the outer target with increasing density and in particular the vanishing ion flux, defined as full detachment, at the inner target cannot be reproduced. The influence of various parameters such as chemical sputtering yields and the effect of the activation of drift terms on the results is analyzed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extension of IMPMC Code Toward Time Evolution Simulation
Authors: Shimizu K. , Takizuka T. , Kawashima H.
Published: March 2008

A self‐consistent modelling of divertor plasma and impurity transport has been developed. The key feature of this integrated code, SONIC, is to incorporate the elaborate impurity Monte Carlo code, IMPMC. Monte‐Carlo (MC) approach is suitable for modelling of interactions between impurities and walls, including kinetic effects, and the complicated dissociation process of hydrocarbons. The MC modelling, however, has the disadvantage for long computational time, large MC noise, and assumption of steady state. The first and second difficulties were solved by developing a new diffusion model and optimizing with a Message Passing Interface (MPI) on the massive parallel computer. The third subject is solved by extension of IMPMC code toward time evolution simulation. A time‐dependent simulation with impurity MC code involves a problem to increase number of test particles. The particle reduction method to resolve this problem is newly developed and is validated. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐Z Impurity Transport Code by Monte Carlo Method in a Realistic Tokamak Geometry – IMPGYRO –
Authors: Hoshino K. , Noritake M. , Toma M. , Hatayama A.
Published: March 2008

We have developed a three‐Dimensional (3‐D) Monte Carlo transport code “IMPGYRO” for heavy metal impurities. The code includes most of important processes of heavy metal impurities, such as the Larmor gyration, Coulomb collisions and multi‐step ionization/recombination processes. The code outputs the 2‐D density profiles of high‐Z impurity for a realistic tokamak geometry. In this paper, the IMPGYRO code has been improved to take into account the self‐sputtering and the thermal force. The normalized density of impurities in the divertor region for the power detached case is larger than that for the attached case. The balance between the friction force and the thermal force possibly explain the tendency. The IMPGYRO code directly solves the 3‐D equation of motion for impurity particles. It is possible to properly calculate the incident angle to the wall for each impurity particle. The incident angle calculated by the IMPGYRO is widely distributed around the incident angle of a magnetic line of force. The sputtering yield greatly depends on the incident angle, especially in the angle range that the incident angle of tungsten is distributed. Therefore, the IMPGYRO code which properly calculates the incident angle is a useful tool to evaluate the angular distribution of incident particles and the resultant amount of the self‐sputtered impurity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of Oblique Magnetic Field on Release Conditions of Dust Particle from Plasma‐Facing Wall
Authors: Tomita Y. , Smirnov R. D. , Takizuka T. , Tskhakaya D.
Published: March 2008

Effects of oblique magnetic field on release condition of a spherical dust particle from a plasma‐facing vertical wall is studied analytically. The magnetic pre‐sheath and the Debye sheath are coupled to obtain the plasma quantities and the electric field at the wall, which are necessary to analyze the release condition. It is clarified that for the deeper potential drop inside the Debye sheath than the floating one the critical radius for release increases as the magnetic field approaches parallel to the wall. The smaller dust than the critical one can be released from the wall. On the other hand in the case of the shallower potential drop the critical radius disappears at some angle of the oblique magnetic field. From this analysis we find that the size of the released dust particle can be controllable by adjusting the plasma parameters such as plasma density and temperature as well as biasing the wall potential. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Dust Statistical Characteristics in Tokamaks
Authors: Smirnov R. D. , Pigarov A. Yu. , Krasheninnikov S. I. , Rosenberg M. , Mendis D. A.
Published: March 2008

In this work we analyze the size (radius) distribution function of dust particles in tokamak plasmas during a steady state discharge. A relation between the radius distribution function of dust in the plasma and the radius distribution of dust injected from tokamak walls is obtained using a Green's function formalism. Numerical simulations of the dust radius distribution function in a tokamak plasma with the Dust Transport (DUSTT) code are used to obtain the analytical form of the Green's function semi‐empirically. It is demonstrated that the Green's function obtained can be used to predict qualitatively the dust size distributions in the tokamak plasmas. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Distinct subsets of human invariant NKT cells differentially regulate T helper responses via dendritic cells
Authors: Liu Tian‐Yi , Uemura Yasushi , Suzuki Motoharu , Narita Yayoi , Hirata Shinya , Ohyama Hideki , Ishihara Osamu , Matsushita Sho
Published: March 2008

Invariant natural killer T (iNKT) cells regulate the T helper (Th) 1/2 balance and elicit either enhancement or suppression of the immune responses. However, the exact mechanism by which iNKT cells exert these contrasting functions has remained elusive. We demonstrate herein that two major distinct subsets of human iNKT cells, CD4+CD8β– (CD4+) and CD4–CD8β– (double negative; DN) cells, express functional CD40 ligand (CD40L), but they differentially regulate the dendritic cell (DC) function by reciprocal NKT‐DC interactions, thereby influencing the subsequent Th response. The CD4 subset stimulated by α‐galactosylceramide (α‐GalCer)‐loaded DC immediately produced massive amounts of IL‐4 and IL‐13, which together with IFN‐γ enhanced CD40L‐induced IL‐12 production by DC. In contrast, the DN subset eliminated the DC by cytolysis and changed the living DC into a default subtype, in turn markedly down‐regulating the levels of IL‐12. Therefore, the DC stimulated by the CD4 subset preferentially induced Th1 responses, whereas the DC reacted with the DN subset induced a shift toward Th2 responses. These findings may provide an important insight into better understanding the contribution of iNKT‐DC cross‐talk governing the Th1/2 balance and the diverse influences of iNKT cells in various diseases.
Superior induction of anti‐tumor CTL immunity by extended peptide vaccines involves prolonged, DC‐focused antigen presentation
Authors: Bijker Martijn S. , van den Eeden Susan J. F. , Franken Kees L. , Melief Cornelis J. M. , van der Burg Sjoerd H. , Offringa Rienk
Published: March 2008

Anti‐tumor vaccines consisting of extended CTL peptides in combination with CpG‐ODN were shown to be superior to those comprising minimal CTL epitopes and CpG‐ODN, in that they elicit stronger effector CTL responses with greater tumoricidal potential. We now demonstrate that this improved performance is primarily due to the focusing of CTL epitope presentation onto activated DC in the inflamed lymph nodes draining the vaccination site. In the case of vaccination with minimal peptides, additional APC including T and B cells are also loaded with CTL epitopes. Our data suggest that circulation of these peptide‐loaded lymphocytes leads to epitope presentation in non‐inflamed lymphoid organs distal from the vaccination site, in the absence of potent costimulatory signals required for efficient CTL priming. The resulting blend of pro‐immunogenic and tolerogenic signals, which results in suboptimal activation of the CTL response, is avoided by vaccinating with extended CTL peptides. An additional advantage of extended CTL peptide vaccines is an increased duration of in vivo epitope presentation.
Chemical Modification of a Bridging Ligand Inside a Metal–Organic Framework while Maintaining the 3D Structure (Eur. J. Inorg. Chem. 10/2008)
Authors: Costa José Sánchez , Gamez Patrick , Black Cory A. , Roubeau Olivier , Teat Simon J. , Reedijk Jan
Published: March 2008

The cover picture shows the post‐synthetic functional group modification of a Metal–Organic Framework without destroying the original 3D architecture. Details are discussed in the Short Communication by P. Gamez et al. on p. 1551 ff. The authors are indebted to the Chemical Research Council of the Netherlands and the Graduate Research School Combination “NRSC Catalysis” for financial support.
A Carbon Nanotube PVC Based Matrix Modified with Glutaraldehyde Suitable for Biosensor Applications
Authors: Pérez‐López Briza , Sola Joan , Alegret Salvador , Merkoçi Arben
Published: March 2008

Carbon nanotubes (CNTs) are offering a great promise for developing electrochemical sensors. Distinctive properties of CNTs such as a high surface area, ability to accumulate analyte, minimization of surface fouling and electrocatalytic activity are very attractive for electrochemical sensing. The electrochemical study of a glassy carbon (GC) electrode coated with a matrix based in multiwall carbon nanotubes (MWCNTs), tetrahydrofuran (THF) mixed with poly(vinyl chloride) (PVC) and with a glutaraldehyde (GA) solution (MWCNTs‐TPG/GC), for β‐Nicotinamide adenine dinucleotide (NADH) detection is discussed in this work using cyclic voltammetry (CV) and chronoamperometry. The used CNTs matrix promotes better the electron transfer of NADH minimizing the fouling effect. The obtained results show remarkable electrochemical and mechanical advantages of MWCNTs‐TPG/GC electrode compared to bare glassy carbon electrode with a great promise for future amperometric biosensors applications.
A multivariate spot filtering model for two‐dimensional gel electrophoresis
Authors: Rye Morten Beck , Alsberg Bjørn K.
Published: March 2008

Image segmentation plays an important role in the automatic analysis of protein spots in 2‐DE. Using image segments representing protein spots, the amount of protein in each segment can be quantified, and corresponding segments can be matched and compared for multiple gels. However, the common presence of image segments caused by noise and unwanted artefacts highly disturb the analysis and comparison of the gels. Common sources of such artefacts are cracks in the gel surface, fingerprints, dust and other pollutions. It would be advantageous to remove these unwanted artefacts during or after the segmentation procedure. To achieve this task a multivariate spot filtering model is developed using image segments from a gel segmentation. Parameters in the model are based on texture, shape and intensity measurements of the image segments. The model successfully managed to separate segments caused by noise, artefacts and cracks from image segments representing true protein spots. The classification method used is discriminant partial least squares regression.
An improved pixel‐based approach for analyzing images in two‐dimensional gel electrophoresis
Authors: Rye Morten Beck , Færgestad Ellen M. , Martens Harald , Wold Jens Petter , Alsberg Bjørn K.
Published: March 2008

An improved pixel‐based approach for analyzing 2‐DE images is presented. The key feature of the method is to create a mask based on all gels in the experiment using image morphology, followed by multivariate analysis on the pixel level. The method reduces the impact of noise and background by identifying regions in the image where protein spots are present, but make no assumption on individual spot boundaries for isolated spots. This makes it possible to detect significant changes in complex regions, and visualize these changes over multiple gels in an easy way. False missing values and spot volumes caused by imposing erroneous spot boundaries are thus circumvented. The approach presented gives improved pixel‐based information from the gels, and is also an alternative to existing methods for data‐reduction, significance testing and visualization of 2‐DE data. Results are compared with software using a common spot boundary approach on an experiment consisting of 35 full size gel images. Gel alignment is required before analysis.
An optimal method of DNA silver staining in polyacrylamide gels
Authors: Han Yan‐Chuang , Teng Cai‐Zhu , Hu Zhong‐Li , Song Yun‐Chun
Published: March 2008

DNA silver staining has widely been used to detect DNA fragments in polyacrylamide gels with high sensitivity. We developed an optimal method for DNA silver staining on polyacrylamide gels. The novel procedure can be completed within 10 min instead of over 20 min with the conventional methods. The sensitivity is significantly improved by the silver‐ion sensitizer (Eriochrome black T (EBT)) and the minimum of 0.11 and 1.75 ng of DNA amount can be detected in denaturing and nondenaturing polyacrylamide gel, respectively. Compared with the conventional silver staining methods, the improved optimal method can save time and display high sensitivity, color uniformity, and long storage time of the staining gels.
Next‐day cognition, psychomotor function, and driving‐related skills following nighttime administration of eszopiclone
Authors: Boyle Julia , Trick Leanne , Johnsen Sigurd , Roach James , Rubens Robert
Published: March 2008

Objective

To evaluate next‐day driving ability, as assessed by brake reaction time (BRT), and cognitive/psychomotor function following nighttime administration of 3 mg eszopiclone.

Methods

Two randomized, double‐blind, placebo‐controlled, cross‐over studies were performed in healthy volunteers (n = 32) and patients with primary insomnia (n = 32). Study participants received nighttime dosing of 3 mg eszopiclone or placebo. BRT and a psychometric test battery were used to assess the next‐day effects of eszopiclone treatment.

Results

In both studies, driving ability and measures of cognitive and psychomotor function were not impaired the morning after eszopiclone, as compared to placebo. All eszopiclone subjects reported improved ease in getting to sleep and quality of sleep with no significant changes in behavior upon awakening. A significant increase in next‐day feelings of sedation was reported in healthy volunteers, but not in patients with primary insomnia, following eszopiclone treatment relative to placebo. Sleep induction, maintenance, duration, and efficiency, as assessed by PSG, were significantly improved following eszopiclone treatment in patients with insomnia.

Conclusions

Nighttime administration of 3 mg eszopiclone improved objective and subjective sleep measures in patients with insomnia (and subjective sleep measures in healthy patients) and did not impair next‐day driving‐related skills or measures of cognition in either study population relative to placebo. Copyright © 2008 John Wiley & Sons, Ltd.
Fast detection of MYCN copy number alterations in brain neuronal tumors by real‐time PCR
Authors: Malakho S.G. , Korshunov A. , Stroganova A.M. , Poltaraus A.B.
Published: March 2008

Increased MYCN gene copy number is a characteristic property of neurogenic tumors. Fluorescence in situ hybridization (FISH) and array‐based comparative genomic hybridization (array‐CGH) are traditionally used to determine MYCN amplification for tumor stratification. A unique ability of real‐time quantitative polymerase chain reaction (qPCR) to determine gene copy number, even within a small percent of observed tumor cells, and can be more appropriate. MYCN genomic copy number from 44 human brain tumors (22 medulloblastomas and 22 neurocytomas) was determined by means of FISH, array‐CGH, and qPCR. By qPCR, with the original set of oligonucleotides, 17 out of 44 (38.6%) tumors were found to contain a 1.3‐ to 2.9‐fold increase of MYCN defined as low‐level gain. An absolute qPCR method was used to get high accuracy of results. Strong correlation was observed between the three methods: for medulloblastomas, r=1 (P<0.01) between FISH and array‐CGH and r=0.92 (P<0.01) between qPCR and FISH/array‐CGH. For neurocytomas, r=0.9 (P<0.01) between FISH and array‐CGH and r=0.34/0.43 (P<0.01) between qPCR and FISH/array‐CGH. Absolute qPCR assays possess high precision compared to other conventional methods and can be used for accurate and quickness detection of MYCN status (low‐level gene gain and amplification). J. Clin. Lab. Anal. 22:123–130, 2008. © 2008 Wiley‐Liss, Inc.
Scale development of a measure to assess community‐based and clinical intervention group environments
Authors: Wilson Patrick A. , Hansen Nathan B. , Tarakeshwar Nalini , Neufeld Sharon , Kochman Arlene , Sikkema Kathleen J.
Published: March 2008

Though group interventions are widely used in community‐based and clinical settings, there are few brief instruments for assessing the group environment. Two studies on the development of a brief measure to assess intervention group environments are described, and psychometric properties of the new scale are presented. The new measure is based on Moos' (1994) Group Environment Scale (GES). Participants in the studies were from two independent randomized controlled clinical trials (RCTs) of group interventions (combined N=334). In Study 1 (N=139), the factor content of the original 90‐item GES was examined. The scale was shortened, the response format was changed, and items were adapted and added to in an effort to increase applicability to community‐based and clinical intervention groups. In Study 2 (N=195), the new scale was evaluated, the factor solution obtained in Study 1 was cross‐validated, and subsequently the length of the scale was shortened again. The final scale contains 25 items with three subscales. Reliability and validity of the new scale was examined. Finally, the research and practice implications of the scale are discussed. © 2008 Wiley Periodicals, Inc.
Diversity within: subgroup differences of youth problem behaviors among asian pacific islander American adolescents
Authors: Choi Yoonsun
Published: March 2008

This study compares problem behaviors across a range of adolescent Asian Pacific Islander (API) subgroups using the Add Health data, and controlling for parental education or immigrant status. The study finds that Filipino, “other” API, and multiethnic API American youth are at higher risk for poorer outcomes than Chinese, Korean, and Vietnamese American counterparts. Many of these differences remained after adjusting for parental education. Controlling for immigrant status explained only some of the subgroup differences. The results suggest several shortcomings to the “model minority” stereotype that is often applied to API American youth. Research and practice should not overlook the higher risk for problem behaviors among certain API American subgroups. The findings highlight the need for more resources for API Americans, especially for the API subgroups facing higher risks. © 2008 Wiley Periodicals, Inc.
Religious coping among African Americans, Caribbean Blacks and Non‐Hispanic Whites
Authors: Chatters Linda M. , Taylor Robert Joseph , Jackson James S. , Lincoln Karen D.
Published: March 2008

This study examined demographic predictors of attitudes regarding religious coping (i.e., prayer during stressful times and look to God for support, strength and guidance) within a national sample of African Americans, Caribbean Blacks, and non‐Hispanic Whites (National Survey of American Life). The findings demonstrate significant Black‐White differences in attitudes regarding religious coping with higher endorsements of religious coping among African Americans and Black Caribbeans (Caribbean Blacks). Comparisons of African Americans and Black Caribbeans revealed both similar and divergent patterns of demographic effects. For both African Americans and Black Caribbeans, women were more likely to utilize religious coping than men and married respondents were more likely than never married respondents to report utilizing prayer when dealing with a stressful situation. Further, for both groups, higher levels of education were associated with lower endorsements of the importance of prayer in dealing with stressful situations. Among African Americans only, Southerners were more likely than respondents who resided in other regions to endorse religious coping. Among Black Caribbeans, those who emigrated from Haiti were more likely than Jamaicans to utilize religious coping when dealing with a stressful episode. © 2008 Wiley Periodicals, Inc.
Electrokinetic chromatography with polymeric pseudostationary phases
Authors: Palmer Christopher P.
Published: March 2008

Recent research and development efforts concerning polymeric pseudostationary phases (PSPs) for electrokinetic chromatography are reviewed. The introduction of new materials, characterization of structural effects on performance and selectivity, applications, and the use of polymeric PSPs with mass spectrometric detection are considered. Very interesting results concerning the effects of polymer structure have been reported. Significant developments have also been reported in the development of novel applications of polymeric PSPs, particularly for sample preconcentration using micellar affinity gradient focusing. The use of mass spectrometric detection with electrokinetic chromatography has seen significant development, and recent reports indicate that this is a robust and sensitive approach.
Aggregation‐Induced Luminescence of Polyisobutene Succinic Anhydrides and Imides
Authors: Pucci Andrea , Rausa Riccardo , Ciardelli Francesco
Published: March 2008

PIB derivatives such as PIBSAs and the corresponding PIBSIs characterized by different contents of functional groups were prepared. They showed luminescence both in their neat form and in heptane solution when the amount of functional groups per polymer chain was higher than a critical value. This behavior is attributed to aggregation‐induced emission, a phenomenon caused by the aggregation of non‐emissive chromophoric carbonyl groups present on PIB derivatives. AIE was studied in heptane solution as a function of the type (SAs or succinimides) and number of interacting functional groups. The results suggest that fluorescence measurements might be an effective tool to determine the degree of functionalization of PIB derivatives.

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Preparation of pH‐Responsive Hydrophilic Core‐Shell Particles for Encapsulation of Water‐Soluble Material
Authors: Park Young‐Ho , Han Joo‐Hyun , Suh Kyung‐Do
Published: March 2008

Dual pH‐responsive PAAc/ PVAm core‐shell particles to encapsulate water‐soluble material were prepared through the deposition of PVAm on the surface of PAAc core particles. The structural characteristics of the core‐shell particles were confirmed by SEM and CLSM. To investigate the release profiles of the core‐shell particles and PAAc core, methylene blue, which is a cationic water‐soluble dye, was introduced. Release profiles were dominantly affected by the core swelling behavior at different pH values. The release rate of the core‐shell was less than the PAAc core, indicating that it is affected by ionic interactions between the particle and the cationic dye.

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Addition Polymers of Strained Cyclic Olefins – Transition Metal Catalysed Polymerisations of the Cyclobutene Derivative Bicyclo[3.2.0]hept‐6‐ene
Authors: Curran Katherine , Risse Wilhelm , Boggioni Laura , Tritto Incoronata
Published: March 2008

Bicyclo[3.2.0]hept‐6‐ene was converted into the corresponding addition polymer poly(6,7‐bicyclo[3.2.0]heptylene) with the aid of early and late transition metal based olefin polymerisation catalysts. Moderate to very good yields (42–99%) of polymer were obtained with [Pd(NCEt)4][BF4]2, [(η3‐allyl)Pd(solv)2][SbF6], [(2,9‐dimethyl‐1,10‐phenanthroline)Pd(CH3)(NC(CH2)6CH3)][SbF6], and Cp2ZrCl2/MAO, using monomer to transition metal ratios between 50/1 and 250/1. Reaction occurs at the olefin π‐bond, and the four‐membered ring of the monomer is retained during polymerisation which differs from ring‐opening olefin metathesis polymerisation in which the four‐membered ring is opened. The nearly exclusively saturated structure of the polymer was confirmed by 1H and 13C NMR spectroscopy. It is proposed that the polymers consist of repeating units that are predominantly cis‐exo‐enchained. GPC analysis of the soluble polymers prepared with [Pd(NCEt)4][BF4]2 showed that the molecular mass values $\overline M _{\rm n}$(GPC) were in the range of 3 700 to 22 600.

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Novel High‐Performance Talc/Poly[(butylene adipate)‐co‐terephthalate] Hybrid Materials
Authors: Raquez Jean Marie , Nabar Yogaraj , Narayan Ramani , Dubois Philippe
Published: March 2008

New talc/PBAT hybrid materials were prepared through reactive extrusion. First, PBAT was free‐radically grafted with MA to improve the interfacial adhesion between PBAT and talc. Then, the resulting MA‐g‐PBAT was reactively melt‐blended with talc through esterification reactions of MA moieties with the silanol functions from talc. Sn(Oct)2 and DMAP were used as catalysts. Interestingly, the tensile properties for these compatibilized composites were improved due to a better interfacial adhesion between both partners. XPS showed the formation of covalent ester bonds between the silanol functions from talc particles, and the MA moieties grafted onto the polyester backbones.

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A Very Useful Redox Initiator for Aqueous RAFT Polymerization of N‐Isopropylacrylamide and Acrylamide at Room Temperature
Authors: Bai Wei , Zhang Liang , Bai Ruke , Zhang Guangzhao
Published: March 2008

Reversible addition fragmentation chain transfer (RAFT) polymerizations of N‐isopropylacrylamide (NIPAM), and acrylamide (AM) were successfully performed in aqueous media at ambient temperature using a redox initiator, potassium persulfate (K2S2O8), and sodium thiosulfate (Na2S2O3). The molecular weight of the polymers obtained increases linearly with monomer conversion, molecular weight distribution is narrow even at high conversion (>90%), and a linear relationship exists between ln([M]0/[M]) and polymerization time. Moreover, self‐chain extension reaction also proceeded successfully. All the results demonstrate that K2S2O8–Na2S2O3 is a very efficient initiating system for the RAFT polymerizations of NIPAM and AM in aqueous media at room temperature.

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Controlled Array of Ferritin in Tubular Nanostructure
Authors: Kim Min Sup , Shin Kwang Min , Kim Sun I. , Spinks Geoffrey M. , Kim Seon Jeong
Published: March 2008

We have demonstrated that uniform and continuous poly(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid) (PAMPS) tubular core‐shell nanostructures containing linear features of ferritin nanoparticles can be directly fabricated using two immiscible solutions employing coaxial electrospinning. By adjusting the concentration of PAMPS as the outer solution in the coaxial electrospinning process, the width of a one dimensional (1D) array of ferritin could be accurately controlled. We demonstrate the formation of a nearly linear chain of individual ferritin particles encapsulated in a PAMPS nanofiber of 40 nm diameter. The ability to accurately control the width of the ferritin 1D arrays encapsulated in tubular nanostructures is a key component in determining the efficiency and performance of nanodevices. The demonstrated method of forming tubular nanostructures containing inner 1D particle arrays can also be extended to other materials with potential applications in nanoelectronic devices, such as nanobiosensors and batteries.

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Low‐Band Gap Polymeric Cyanine Dyes Absorbing in the NIR Region
Authors: Geiger Thomas , Benmansour Hadjar , Fan Bin , Hany Roland , Nüesch Frank
Published: March 2008

Two new, fully conjugated polymeric cyanine dyes based on trimethine and heptamethine moieties have been synthesized. Both polymers were characterized by gel permeation chromatography, UV‐vis and IR spectroscopy, elementary analysis and cyclic voltammetry. The structure of one material could be confirmed with NMR spectroscopy. Upon head‐to‐tail coupling of the dye moieties distinct bathochromic shifts up to 159 nm were observed for the polymers which absorb solely in the near infrared (NIR) region with maxima up to 1 002 nm and very high molar absorption coefficients. This highly efficient absorption in the NIR spectral domain combined with the strong electron accepting properties makes these dyes interesting candidates for many optical applications; investigations on photovoltaic devices based on polymeric cyanine dye/C60 heterojunctions identify one of these possibilities.

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Fatigue strength estimation of butt welded joints in magnesium AZ31 alloy using the genetic algorithm
Authors: Karakas Ö. , Canyurt O. E. , Gulsoz A.
Published: March 2008

Genetic Algorithm is applied to calculate the substitute structural length (SSL) and obtain the fatigue strength of welded joints in magnesium. Fatigue tests with unnotched and notched specimens of the base material metal (BM), the weld metal (WM) and the heat‐affected zone (HAZ) of magnesium AZ31 (MgAl3) were carried out in order to derive the unknown substitute structural length. Results of fatigue tests with geometrically similar welded joints with full and partial penetration were available. The comparison of the experimental and predicted substitute structural length using Genetic Algorithm Substitute Structural Length Estimation Model (GASLEM) shows that the developed models seem to be capable of predicting the SSL values. Fatigue strength values were also obtained using predicted SSL.
Microstructure‐oriented characterisation of the cyclic deformation behaviour of Ti‐6Al‐4V
Authors: Rojek N. , Smaga M. , Walther F. , Eifler D.
Published: March 2008

In this paper, the cyclic deformation behaviour of the titanium alloy Ti‐6Al‐4V is characterised in uniaxial stress‐ and total‐strain‐controlled load increase and constant amplitude tests at ambient temperature by means of mechanical stress‐strain hysteresis and temperature measurements. The measured physical values obviously show a pronounced interrelation with the underlying fatigue processes and represent the actual fatigue state. In selected experiments the influence of elevated temperatures on the cyclic deformation behaviour was investigated. Using the plastic strain amplitude and the change of the specimen temperature with the physically based lifetime calculation “PHYBAL” an excellent accordance with experimentally determined lifetimes could be realised. Microstructural changes were evaluated by transmission electron microscopy in defined fatigue states, additionally, the fracture surface was analysed by scanning electron microscopy.
Über adiabatic shearbands und die Entstehung der „Steilen Weißen Bänder”︁ in Wälzlagern
Authors: Schlicht H.
Published: March 2008

Bei der Überrollung von Wälzelementen entstehen nach überelastischen Beanspruchungen unter der Laufbahnoberfläche strukturelle Veränderungen. Mikro‐ und makroplastische Verformungen des Gefüges infolge der dreiachsigen Beanspruchung begleiten den Wälzermüdungsprozess vom ersten Lastwechsel an. Sie bestimmen die Lebensdauer des Wälzelements.

Man beobachtet neben den plastischen Verformungen des Gefüges des Weiteren die sog. „butterflies”︁ und die sog. flachen und steilen „Weißen Bänder”︁. Diese Gefüge sind nicht anätzbar. Die weißen Bänder entstehen bei Kugellagern erst nach einer größeren Anzahl von Überrollungen und liegen im Umfangsschnitt unter ≈ 30 ° bzw. ≈ 80 ° zur Kontaktfläche. Die butterflies und die weißen Bänder entstehen offenbar infolge einer zweiachsigen Werkstoffbeanspruchung. Ein Einfluss auf die Lebensdauer ist nicht erwiesen. Struktur und Entstehungsmechanismus sind strittig.

Es gibt Gefügeerscheinungen, die den butterflies und den weißen Bändern ähnlich sind, die sog. adiabatic shearbands. Diese entstehen nach einer lokalen Makro‐Scherung des Gefüges, ausgelöst durch eine einmalige, extrem kurzzeitige Druck‐Scher‐Beanspruchung. Blitztemperaturen nahe dem Schmelzpunkt verursachen im Scherbereich bei martensitisch gehärteten Werkstoffen die Bildung von Neuhärtungszonen; auch diese Gefüge sind nicht anätzbar.

Der vorliegende Aufsatz beschäftigt sich mit der Frage, ob während des stetig und langzeitig ablaufenden Prozesses der plastischen Verformungen eine Beanspruchungskonstellation entsteht, die die adiabatische Bildung von butterflies und von weißen Bändern ermöglicht. Berücksichtigt man jüngste Erkenntnisse zur Wälzermüdung sowie zur Werkstoffbeanspruchung durch eine EHD‐Strömung, dann darf man zumindest die „Steilen Weißen Bänder”︁ als adiabatic shearbands ansehen.
Rheologisches Verhalten hochgefüllter Kunststoffe. Einfluss der Füllstoffe
Authors: Markov A.V.
Published: March 2008

Im Rahmen dieser Arbeit wurde das Fliessverhalten gefüllter thermoplastischer Polymere untersucht. Es wurde gezeigt, dass die rheologischen Eigenschaften hochgefüllter Kunststoffe im Allgemeinen vom Fließverhalten des Matrixpolymers, den Eigenschaften und der Struktur der dispersen Phase und Wechselwirkungen zwischen Polymer und Füllstoff sowie zwischen den einzelnen Füllstoffpartikeln abhängig sind. In der Arbeit wurde das theoretische Verhältnis zwischen der Viskosität von gefüllten und ungefüllten Polymeren als Funktion des Füllstoffgehalts und der Wechselwirkungen zwischen den Komponenten vorgeschlagen. Auf Basis des entwickelten Modells kann man die stochastische Struktur des gefüllten Materials und die nicht linearen viskosen Eigenschaften der Kunststoffschmelze berücksichtigen.
The influence of the electroplating parameters on the conditions of deposited nickel‐iron coatings
Authors: Hoffmann J. E. , Bedner K. , Clemens H. , Degen R. , Dhum C. , Giro F. , Kirsch U. , Schmitt M. , Saumer M.
Published: March 2008

Several specific electroplating parameters are varied to develop a manufacturing process for nickel‐iron coatings with low residual stresses and favourable structures and hardness values. Here, the produced coating conditions on the surface are characterised according to alloy compositions, microstructures, residual stresses, texture and microhardness as well as the elastic indentation modulus. The manufacture of the coatings was carried out in a laboratory electroplating plant. The process parameters are: electroplating in electrolytic baths with and without saccharin as an additive, with different iron content as well as with various current parameters. The results show significant influences of saccharin, as a bath additive, and of the pulse frequency during the reverse current pulse procedure on the coating conditions. Supplementary investigations are scheduled for determining the distributions of the conditions through the coating thickness. Similarly, micromechanical tests are planned. Process parameters with optimal conditions can then be selected from the determined process‐condition property relation. This is to subsequently serve as the basis for improving the manufacture of micro gear‐wheels. The micro gear‐wheels are produced by electroforming using the direct LIGA process.
Examining item bias in the anxiety subscale of the Hospital Anxiety and Depression Scale in patients with chronic obstructive pulmonary disease
Authors: Tang Wai‐Kwong , Wong Eric , Chiu Helen F. K. , Lum C. M. , Ungvari Gabor S.
Published: March 2008

The Hospital Anxiety and Depression Scale (HADS) is a widely used screening instrument for depression and anxiety in medically compromised patients. The purpose of this study was to examine the differential item functioning (DIF) of the anxiety subscale of the HADA (HADS‐A). A research assistant administered the HADS‐A to 166 Chinese patients with chronic obstructive pulmonary disease (COPD) who were consecutively admitted to a rehabilitation hospital. Although the HADS‐A was overall uni‐dimensional, there were one mute item and two items with borderline misfit. Only one item had a DIF for arterial oxygen saturation. No item had DIF for other indicators of the severity of COPD. In conclusion, this study found that for one item the HADS‐A has significant item bias for the severity of disease in patients with COPD. Copyright © 2008 John Wiley & Sons, Ltd.
An energy‐efficient node‐scheduling scheme for wireless sensor networks based on minimum dominating sets
Authors: Pazand Babak , Datta Amitava
Published: March 2008

One of the major requirements for new wireless sensor networks is to extend the lifetime of the network. Node‐scheduling techniques have been used extensively for this purpose. Some existing approaches rely mainly on location information through global positioning system (GPS) devices for designing efficient scheduling strategies. However, integration of GPS devices with sensor nodes is expensive and increases the cost of deployment dramatically. In this paper we present a location‐free solution for node scheduling. Our scheme is based on a graph theoretical approach usingminimum dominating sets. We propose a heuristic to extract a collection of dominating sets. Each set consists of a group of working nodes which ensures a high level of network coverage. At each round, one set is responsible for covering the sensor field while the nodes in other sets are in sleep mode. We evaluate our solution through simulations and discuss our future research directions. Copyright © 2008 John Wiley & Sons, Ltd.
Analytical integration of singular kernels in symmetric boundary element analysis of Kirchhoff plates
Authors: Mazza M. , Leonetti L. , Aristodemo M.
Published: March 2008

An analytical integration method for evaluating the singular integrals arising in the construction of symmetric boundary element models is proposed, referring to the analysis of Kirchhoff plates. Kernels involved in the symmetric boundary formulation of Kirchhoff plates exhibit singularities up to O(1/r4). The proposed technique temporarily deactivates the singularities by using a limit approach and carries out the integration on contiguous boundary elements in order to smooth the singularities of the kernels through sufficiently continuous shape functions. The paper contains a brief presentation of the boundary integral formulation of the Kirchhoff plate, with the explicit expressions of the fundamental solutions involved and the derivation of the symmetric boundary element model. A detailed description of the proposed integration technique is presented, which discusses the main steps of the analytical procedure and provides the final results. The technique is illustrated through the discussion of a series of relevant cases, including high singularities and referring to both collinear and corner supports. Copyright © 2008 John Wiley & Sons, Ltd.