bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of growth temperature on the optical properties of InN nanostructures grown by MOCVD
Authors: Sun Yuanping , Cho Yong‐Hoon , Wang Hui , Wang Lili , Zhang Shuming , Yang Hui 
Published: May 2010

AbstractThe non‐intentionally doped InN nanostructures with different sizes were grown by metal‐organic chemical vapor deposition at different temperatures. Atomic force microscope images show that the structure of InN nanostructures sample is hexagonal with a height of 33.6, 52.5 and 132.6 nm for sample A to C, which corresponding to the growth temperature of 475, 500 and 525 °C, respectively. The height of wetting layers decided by the air‐bearing surface (ABS) analysis is 3.8, 5.8 and 16.0 nm for sample A to C, respectively. The main emission peak at 12 K for sample A to C is 0.806, 0.760 and 0.755 eV, respectively, which is related to the height of wetting layer and size of nanostructures. By the best theoretical fitting of the main emission peaks, an almost same band‐gap value of 0.712 eV with an error 0.001 eV is obtained. The difference of main emission energy and the band gap energy was caused by the recombination of degenerate electrons with photo‐holes near the top of the valence band (Burstein‐Moss effect) together with the quantum confinement effect. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In situ SiN passivation of AlInN/GaN heterostructures by MOVPE
Authors: Behmenburg H. , Khoshroo L. Rahimzadeh , Mauder C. , Ketteniss N. , Lee K. H. , Eickelkamp M. , Brast M. , Fahle D. , Woitok J. F. , Vescan A. , Kalisch H. , Heuken M. , Jansen R. H. 
Published: May 2010

AbstractAlInN is being considered to replace AlGaN as barrier material in high‐electron mobility transistors (HEMT) mainly due to the possibility to downscale the barrier layer thickness at coexistent higher drain current density. However, the stability of surface conditions which can strongly influence the electrical properties of the device has to be assured. In situ deposition of a SiN passivation layer by metal‐organic vapour phase epitaxy (MOVPE) is therefore a promising candidate to improve the device structure. In this paper, heterostructures with thin AlInN barrier passivated by in situ deposition of SiN layers of different thicknesses are presented. As expected, deterioration of the sheet resistance (RSh) was observed for the reference sample without SiN passivation layer by continuously performed RSh mappings of the investigated wafer. This change is noticeably reduced for samples with in situ SiN passivation layer. A comparison of two wafers, stored either with or without air exposure, reveals oxidation as presumable reason for the deterioration. Further, results from RSh measurements on processed wafers indicate an enhanced RSh stability during process for SiN‐capped samples. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scaling behavior of plasmon coupling in Au and ReO3 nanoparticles incorporated in polymer matrices
Authors: Maitra Urmimala , Ghosh Sandeep , Biswas Kanishka , Rao C. N. R. 
Published: May 2010

AbstractPolymer nanocomposites containing different concentrations of Au nanoparticles have been investigated by small angle X‐ray scattering and electronic absorption spectroscopy. The variation in the surface plasmon resonance (SPR) band of Au nanoparticles with concentration is described by a scaling law. The variation in the plasmon band of ReO3 nanoparticles embedded in polymers also follows a similar scaling law.magnified imageDistance dependence of plasmon coupling in polymer composites of metal nanoparticles.(© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Using age and usage for prediction of reliability of an arbitrary system from a finite population
Authors: Lu Lu , Anderson‐Cook Christine M. 
Published: May 2010

AbstractFor single‐use non‐repairable systems, reliability is commonly estimated as a function of age and usage. For the effective management of individual systems or populations of systems, it is frequently important and necessary to predict the reliability in the future for age and usage values not yet observed. When predicting future system reliability, the age of the future system is easily predicted whereas future usage values will typically be unknown. In this paper we present the methodology for how to estimate both individual and population reliability summaries based on the currently known age and usage values. Projected usage values for future points in time can be obtained based on observed usage patterns or user‐specified patterns of usage rates. Individual system summaries can be used to answer the questions ‘For a given system of age A and usage U, what is its reliability with associated uncertainty?’ or ‘For a given system with known current age A and usage U, but unknown usage in the future, what is its reliability with associated uncertainty?’ The population summary of interest predicts the probability that a system randomly selected from the population of systems works. This summary takes into consideration the estimation of future usage, the estimated probability of individual systems working at their given ages and usage values, and the life cycle demographics of the population of interest. In this paper we discuss these questions for a given application. Published in 2010 by John Wiley & Sons, Ltd.
A simple control scheme for the manipulation of a particle by means of optical tweezers
Authors: Aguilar‐Ibañez Carlos , Suarez‐Castanon Miguel S. , Rosas‐Soriano Luis I. 
Published: May 2010

AbstractWe present a simple control scheme for changing the position of a microscopic particle immersed in a viscous medium and trapped by optical tweezers. We derive a simple feedback controller under the consideration that the particle mass is so small that it can be discarded from the motion equations. This approximation is well justified in practice, since the inertial force produced by the motion of a micron‐scaled trapped particle is completely dominated by the medium viscous drag force. Finally, we formally prove that the obtained controller is able to globally asymptotically stabilize the system when the particle mass is considered, if some suitable values of some control parameter are used. The stability analysis of the controlled system was carried out by using the standard Lyapunov stability theory. Also, by means of numerical simulations, we show that the obtained closed‐loop system is robust when random thermal noise is presented. Copyright © 2010 John Wiley & Sons, Ltd.
Vision‐based autonomous convoying with constant time delay
Authors: Goi Hien K. , Giesbrecht Jared L. , Barfoot Timothy D. , Francis Bruce A. 
Published: May 2010

AbstractThis paper describes the design and experimental validation of a vision‐based vehicle‐following system that uses only onboard sensors to enable a convoy of follower vehicles to autonomously track the trajectory of a manually driven lead vehicle. The tracking is done using the concept of a constant time delay, in which a follower tracks the delayed trajectory of its leader. This constant‐time‐delay approach allows for new techniques to be used to estimate the speed and heading of the leader. Experiments were conducted with full‐sized military vehicles on a 1.3‐km test track. Successful field trials with one follower for 10 laps and with two followers for 13.5 laps, totaling over 30 km, are presented. © 2010 Government of Canada. Exclusive worldwide publication rights in the article have been transferred to Wiley Periodicals, Inc., AWiley Company.
1‐Point RANSAC for extended Kalman filtering: Application to real‐time structure from motion and visual odometry
Authors: Civera Javier , Grasa Oscar G. , Davison Andrew J. , Montiel J. M. M. 
Published: May 2010

AbstractRandom sample consensus (RANSAC) has become one of the most successful techniques for robust estimation from a data set that may contain outliers. It works by constructing model hypotheses from random minimal data subsets and evaluating their validity from the support of the whole data. In this paper we present a novel combination of RANSAC plus extended Kalman filter (EKF) that uses the available prior probabilistic information from the EKF in the RANSAC model hypothesize stage. This allows the minimal sample size to be reduced to one, resulting in large computational savings without the loss of discriminative power. 1‐Point RANSAC is shown to outperform both in accuracy and computational cost the joint compatibility branch and bound (JCBB) algorithm, a gold‐standard technique for spurious rejection within the EKF framework. Two visual estimation scenarios are used in the experiments: first, six‐degree‐of‐freedom (DOF) motion estimation from a monocular sequence (structure from motion). Here, a new method for benchmarking six‐DOF visual estimation algorithms based on the use of high‐resolution images is presented, validated, and used to show the superiority of 1‐point RANSAC. Second, we demonstrate long‐term robot trajectory estimation combining monocular vision and wheel odometry (visual odometry). Here, a comparison against global positioning system shows an accuracy comparable to state‐of‐the‐art visual odometry methods. © 2010 Wiley Periodicals, Inc.
The maximal probability that k‐wise independent bits are all 1
Authors: Peled Ron , Yadin Ariel , Yehudayoff Amir 
Published: May 2010

AbstractA k‐wise independent distribution on n bits is a joint distribution of the bits such that each k of them are independent. In this paper we consider k‐wise independent distributions with identical marginals, each bit has probability p to be 1. We address the following question: how high can the probability that all the bits are 1 be, for such a distribution? For a wide range of the parameters n,k, and p we find an explicit lower bound for this probability which matches an upper bound given by Benjamini et al., up to multiplicative factors of lower order. In particular, for fixed k, we obtain the sharp asymptotic behavior. The question we investigate can be viewed as a relaxation of a major open problem in error‐correcting codes theory, namely, how large can a linear error‐correcting code with given parameters be?The question is a type of discrete moment problem, and our approach is based on showing that bounds obtained from the theory of the classical moment problem provide good approximations for it. The main tool we use is a bound controlling the change in the expectation of a polynomial after small perturbation of its zeros. © 2011 Wiley Periodicals, Inc. Random Struct. Alg., 38, 502–525, 2011
Policy analysis for online game addiction problems
Authors: Park Bong‐Won , Ahn Jae‐Hyeon 
Published: May 2010

AbstractWith the worldwide popularity of online games, game addiction is a serious social issue. To address online game addiction problems and pursue the steady growth of the online gaming industry, we propose and evaluate two policies using a system dynamics approach: a self‐regulation policy and a tax and rebate policy. Through our analysis, we demonstrate that the tax and rebate policy can be a very effective policy measure. Contrary to the concern of most game companies, by implementing the tax and rebate policy while the total revenue of the online gaming industry increases slightly, the social image of gaming improves and the number of addicted game users decreases. This clearly demonstrates that restricting excessive use of games actually benefits online game companies as well as society in general, and that the system can be more efficiently implemented by the tax and rebate policy. Copyright © 2010 John Wiley & Sons, Ltd.
Economic transition management in a commodity market: the case of the Iranian cement industry
Authors: Ghaffarzadegan Navid , Tajrishi Amir T. 
Published: May 2010

AbstractEconomic transition management is an important issue in countries that have not completely adjusted to the market economy style, as well in countries that temporarily implement price controls. The common concern is to manage the transition in a way that lessens the socio‐economic side effects of the process. This paper presents policy recommendations for the Iranian cement industry, which will undergo such a transition. Building on the commodity model literature and supported by interviews with different stakeholders in the industry, we develop a cement price model and calibrate it for Iran's economy. In the base run, we predict a large overshoot in price before it reaches its long‐term equilibrium state. Experimenting with the model, we suggest a specific transition policy which starts from drastic rise(s) in price before leaving the price up to the market. In addition, this paper gives some insights into analyzing similar economic policy problems. Copyright © 2010 John Wiley & Sons, Ltd.
Generic structure to simulate acceptance dynamics
Authors: Ulli‐Beer Silvia , Gassmann Fritz , Bosshardt Mathias , Wokaun Alexander 
Published: May 2010

AbstractSocial behaviour patterns and social equilibrium states are often guided by stable values such as social norms. However, changing environmental conditions (e.g. climate warming, resource scarcity) may require behavioural change and the acceptance of new technologies. Antecedents of aggregate behavioural change are value changes that predetermine when new behaviour patterns emerge and a new social equilibrium state can be reached. The paper addresses these phenomena. First, based on a waste recycling model, we explain these phenomena and develop a simple, generic mathematical model describing the basic traits of acceptance–rejection dynamics. Second, we propose a generic model structure for the simulation of acceptance–rejection behaviour that represents the dynamical characteristics of paradigm change processes. We show that a fourth‐order potential function is a sine qua non for an adequate representation of a paradigm change. Third, we also explain why the well‐known Bass model is unable to capture acceptance and rejection dynamics. Copyright © 2010 John Wiley & Sons, Ltd.
A provably secure threshold signature scheme based on DDH assumption
Authors: Lin Xiaodong 
Published: May 2010

AbstractThreshold signature is an important cryptographic primitive, which was introduced by Desmedt and Frankel in 1991. In a (t, n) threshold signature scheme, a group secret key is distributed among n parties. Later, any t or more parties can use their shares of secret key to generate valid signatures on behalf of the group, while any t−1 or less parties cannot. Over the past years, many excellent threshold signature schemes have been proposed, but few of them provide the provable security proof. Therefore, in this paper, based on Decisional Diffie–Hellman (DDH) assumption, we present a new (t, n) threshold signature scheme and use the techniques from provable security to analyze its security. Copyright © 2010 John Wiley & Sons, Ltd.
Depth‐profiling analysis of MOCVD‐grown triple junction solar cells by SIMS
Authors: Téllez Helena , Vadillo José M. , Messmer Egbert Rodríguez , Miguel‐Sánchez Javier , Laserna J. Javier 
Published: May 2010

AbstractDynamic secondary ion mass spectrometry (d‐SIMS) has been applied to the analysis of the multilayered structure of GaInP/Ga(In)As/Ge concentration photovoltaic devices fabricated by metal organic chemical vapour deposition (MOCVD). Within the arsenal of techniques required to characterize such devices, SIMS represents the most powerful one due to the complete atomic/molecular information provided, its excellent sensitivity and reproducibility. Under Ar+ sputtering, the sample oxidation state is preserved, allowing for the location of interlayer oxides that may appear during the fabrication. Copyright © 2010 John Wiley & Sons, Ltd.
Comparison of MeV monomer ion and keV cluster ToF‐SIMS
Authors: Jones Brian N. , Matsuo Jiro , Nakata Yoshihiko , Yamada Hideaki , Watts John , Hinder Steven , Palitsin Vladimir , Webb Roger 
Published: May 2010

AbstractRecent results1 show the potential of using monomer primary ions accelerated to several MeV with a tandem accelerator to achieve the necessary secondary ion yields to image large (above 1 kDa) molecules with submicron lateral resolutions. The Surrey ion Beam Centre (Surrey IBC) has designed a time‐of‐flight secondary ion mass spectrometer (ToF‐SIMS) combined with a 2 MV Tandem accelerator to investigate the characteristics of the desorption of secondary ions by the impact of fast, heavy, primary ions. The application of this MeV‐ToF‐SIMS technique is intended to eventually image biomolecules in the subcellular regime without the need for matrix application associated with other mass spectromery techniques, such as Matrix Assisted Laser Desorption ionisation (MALDI). A discussion is given to point out the merits of using a combination of Particle‐Induced X‐ray Emission Spectrometry (PIXE) and Rutherford Backscattering (RBS) with the MeV‐ToF‐SIMS measurement to improve quantification and sensitivity of this surface analysis technique. We also present data from highly focused MeV primary ions to directly compare results obtained using keV cluster‐SIMS to measure various biological materials using ToF‐SIMS through sputtering in both the nuclear and electronic stopping regimes. Our findings show that the mass spectra obtained with MeV ions in the electronic stopping regime show similarities to those acquired with more conventional keV ion beams (e.g. Bi+, Bi3+, Bi5+ and C60+). MeV‐ToF‐SIMS has the potential for becoming a widely used quantitative surface analysis technique in the many ion beam analysis facilities already conducting‐high energy ion beam analyses. Copyright © 2010 John Wiley & Sons, Ltd.
Investigation of fullerene depth distribution in PMMA‐C60 blends using dual beam ToF‐SIMS
Authors: Py M. , Barnes J. P. , Charbonneau M. , Tiron R. , Buckley J. 
Published: May 2010

AbstractNanocomposites, and in particular, Polymer–Fullerene blends, have recently drawn strong attention owing to their properties and their numerous applications in new‐generation electronic and optoelectronic devices. The fullerene concentration in the material is critical since it dictates its electrical behavior. In this context, precise knowledge of the fullerene depth distribution in the blends is needed. Here, we investigate the capability of the ToF‐SIMS technique to provide quantitative information on PMMA‐C60 blends with extremely small C60 concentrations. Smooth PMMA layers of ∼130 nm thickness ranging from 0 to 0.04 wt% C60 were deposited on Si wafers. Samples were analyzed with an ION‐TOF TOF SIMS V instrument in negative mode. Using low‐energy Cs+ sputtering (250 eV) and Bi3+ as the analysis ion allowed monitoring of C60 characteristic secondary ions, namely C60− and its isotopes at m = 720,721,722,723,724,725 u. Operating the beams in noninterlaced mode enabled successful depth profiling of samples with very little signal decay. Improvement of depth resolution was achieved by cooling the sample while profiling; AFM study of crater bottoms showed reduced roughness at low temperature, justifying the improvement. Segregation in depth of C60 against PMMA was not observed, in agreement with surface free energy values determined by a contact angle method. Point‐by‐point normalization of C60 signal (C60−, m = 720 u) to PMMA monomer signal (C5H9O2−, m = 101 u) was found to give a linear function of C60 concentration with excellent regression coefficient. Copyright © 2010 John Wiley & Sons, Ltd.
C60 molecular depth profiling of bilayered polymer films using ToF‐SIMS
Authors: Mouhib T. , Delcorte A. , Poleunis C. , Bertrand P. 
Published: May 2010

AbstractDual‐beam time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) (sputter ion, 15 keV C60+; analysis ion, 15 keV Ga+) was used to depth profile two types of spin cast bilayered films, Poly(vinyl pyrrolidone) (PVP)/poly(methyl methacrylate) (PMMA) and poly(4‐vinyl pyridine) (P4VP)/PMMA on silicon substrates. Positive and negative ion molecular depth profiles were obtained and compared on the basis of the stability of the characteristic secondary ion intensities, the sputter rates of the polymers, and the interface widths between the polymer layers and at the silicon substrate. The sputter rates of the top polymer in the bilayered films were typically the same as for the corresponding single‐layer films. However, the presence of a P4VP top layer significantly decreased the sputter rate of the underlying PMMA films. Typical interface widths between adjacent polymer layers were less than the polymer‐silicon interface widths. Additionally, the bilayered films with the P4VP on the outermost surface had higher interface widths. Copyright © 2010 John Wiley & Sons, Ltd.
A robust weighted Kaplan–Meier approach for data with dependent censoring using linear combinations of prognostic covariates
Authors: Hsu Chiu‐Hsieh , Taylor Jeremy M. G. 
Published: May 2010

AbstractThe weighted Kaplan–Meier (WKM) estimator is often used to incorporate prognostic covariates into survival analysis to improve efficiency and correct for potential bias. In this paper, we generalize the WKM estimator to handle a situation with multiple prognostic covariates and potential‐dependent censoring through the use of prognostic covariates. We propose to combine multiple prognostic covariates into two risk scores derived from two working proportional hazards models. One model is for the event times. The other model is for the censoring times. These two risk scores are then categorized to define the risk groups needed for the WKM estimator. A method of defining categories based on principal components is proposed. We show that the WKM estimator is robust to misspecification of either one of the two working models. In simulation studies, we show that the robust WKM approach can reduce bias due to dependent censoring and improve efficiency. We apply the robust WKM approach to a prostate cancer data set. Copyright 2010 John Wiley & Sons, Ltd.
Effects of acute cocaine or dopamine receptor agonists on AMPA receptor distribution in the rat nucleus accumbens
Authors: Ferrario Carrie R. , Li Xuan , Wolf Marina E. 
Published: May 2010

AbstractChanges in α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate receptor (AMPAR) surface expression in the rodent nucleus accumbens (NAc) are produced by cocaine exposure and implicated in addiction‐related behaviors. The direction of change depends on the animal's prior drug history. However, little is known about the effect of a single exposure to cocaine on AMPAR distribution in the NAc of untreated rats. This is essential information for interpreting the literature on AMPAR trafficking after repeated cocaine exposure. In this study, we used a protein crosslinking assay to determine the effect of a single cocaine injection on surface and intracellular AMPAR subunit levels in the rat NAc. We found increased AMPAR surface expression in the NAc 24 h, but not 30 min or 2 h, after cocaine injection. A major effect of cocaine is to increase extracellular dopamine (DA) levels, leading to DA receptor activation. Therefore, we also evaluated the effects of directly acting DA receptor agonists. In contrast to the effects of cocaine, AMPAR surface expression was significantly decreased 24 h after injection of the D2‐class agonist quinpirole, whereas no significant effects were produced by the D1‐class agonist SKF 81297 or the mixed DA agonist apomorphine. Our results show that the effects of a single cocaine exposure in drug‐ and injection‐naïve rats are distinct from those previously reported after repeated cocaine administration. They further suggest that cocaine exerts these effects by influencing neuronal circuits rather than simply stimulating NAc DA transmission. Synapse 65:54–63, 2011. © 2010 Wiley‐Liss, Inc.