bluuebunny/crossref_metadata_2025_split huggingface dataset:
Benchmarking bucky gel actuators: Chemically modified commercial carbon nanotubes versus super‐growth carbon nanotubes
Authors: Biso Maurizio , Ansaldo Alberto , Futaba Don N. , Hata Kenji , Ricci Davide 
Published: August 2010

AbstractBucky gels are considered novel electro active polymers based on carbon nanotubes (CNTs). They are used to make electrochemical actuators that operate with a solid polymer electrolyte and so can work in air at low voltage (2–4 V) for long time with a maximum strain of approximately 1% and operating frequencies of a few tens of Hertz. It is reported in literature that the use of super‐growth carbon nanotubes (SG‐CNTs) affords the preparation of a composite with increased actuation performance that may considered the ‘benchmark’ material. We have recently shown a chemical route to modify single walled carbon nanotubes (SW‐CNTs) with aromatic diamines (SW‐amide) that significantly enhances the performance of bucky gel actuators through increasing the binding between CNTs. In this paper we compare the actuation performance of bucky gels made using chemically modified SW‐CNTs with the one achieved using pristine SG‐CNTs. The unique properties of SG‐CNTs allow the preparation of actuators that outperform the ones made from pristine commercial CNTs in strain‐charge and strain‐frequency response but when SW‐amide based actuators are compared with those made from SG‐CNTs they show similar performances that stem from the increased binding between CNTs induced by the chemical modification.
Nuclear magnetic resonance and magnetization study of surfactant‐coated epsilon‐Co nanoparticles
Authors: Hines William , Budnick Joseph , Perry David , Majetich Sara , Booth Ryan , Sachan Madhur 
Published: August 2010

AbstractA combination of 59Co spin‐echo nuclear magnetic resonance (NMR) and dc magnetization measurements have been carried out on two samples of surfactant‐coated Co nanoparticles in disordered assemblies; 6.5 nm diameter ε‐Co and 12 nm diameter hcp‐Co. The ε‐Co nanoparticles exhibit superparamagnetic behavior with a blocking temperature TB = 70 K, while the hcp‐Co nanoparticles remain ferromagnetic up to room temperature. In addition, the initial susceptibility for the ε‐Co nanoparticles can be described by the Curie–Weiss law with a negative Θ = −158 K. The NMR signal from the hcp‐Co sample is strong at 77 K with no applied magnetic field; the spectra are straightforward and similar to that for bulk hcp Co. However, the NMR signal from the ε‐Co sample is not detectable at 77 K, even with fields up to 7.5 kOe. A NMR signal appears at 4.2 K; the echo amplitude increases dramatically with applied field. The spectra, which must be corrected for T2 effects, are quite broad and characteristic of the small particle size. Due to the broadening, there were no observable spectral features which could be assigned to the two Co sites in crystalline ε‐Co. The results are discussed in the light of interparticle interactions which reduce the initial susceptibility and lead to negative Θ‐values. Estimates are given for the magnetic dipolar and magnetocrystalline anisotropy energies of the particles in both samples.
First‐principles calculations of atomic and electronic properties of ZnO nanostructures
Authors: Xu H. , Fan W. , Fang D. , Rosa A. L. , Frauenheim Th. , Zhang R. Q. 
Published: September 2010

AbstractWe employ density‐functional theory within the generalized‐gradient approximation to investigate the formation energies and atomic and electronic structure of ZnO nanowires and nanotubes (NTs). We find that relaxations on the facets of the bare wires are very similar to those in nonpolar $(10{\bar {1}}0)$ surfaces and play an important role in stabilizing the nanowires. All bare wires are found to be semiconducting, with band gaps larger than that in bulk ZnO. We further investigated hydrogen and water adsorption on ZnO nanowires. We find that the electronic structure of ZnO nanowires can be tuned by hydrogen adsorption and that adsorption of water leads to dissociation of a half‐monolayer. Next, the stability of ZnO NTs has been investigated. We show that multiwall NTs are more stable than single‐walled tubes. Finally, point defects in ZnO NTs have been investigated using spin‐polarized calculations. All calculations were shown to introduce defect levels in the band gap, thus changing the electronic structure of the NTs drastically.
An automated velocity dealiasing method based on searching for zero isodops
Authors: Li Nan , Wei Ming 
Published: August 2010

AbstractA new automated velocity dealiasing method based on zero isodop searching has been developed primarily for linear wind fields. Its essence is to partition the radial velocity field obtained with a Doppler radar into two distinct regions of opposite velocity signs by two zero isodops. Zero isodops are searched point by point from the radar origin to the maximum detection range, and the accepted sign of each region separated by the zero isodops is determined. After that, the velocity sign at each gate is compared with the accepted sign of the region wherein the gate is. If they are consistent, the velocity is true; otherwise it is dealiased. Dealiasing results in real cases indicate that the new algorithm is practicable and effective, especially on aliasing lack of references affected by discontinuous echo or range folding, which is difficult for traditional methods of space continuity checking. Copyright © 2010 Royal Meteorological Society
Change detection in the Cox Proportional Hazards models from different reliability data
Authors: Li Zhiguo , Zhou Shiyu , Sievenpiper Crispian , Choubey Suresh 
Published: August 2010

AbstractThe Proportional Hazards (PH) model is an important type of failure time regression model which relates the occurrence probability of critical failures to influential factors. However, little research work has been done on detecting changes in the PH models fitted based on different sets of reliability data. This paper develops the methods for change detection in the Cox PH models, also known as Semiparametric PH model, for reliability prediction and/or assessment of the time‐to‐failure data collected from different subjects. The effectiveness of the developed methods is illustrated through numerical studies and real‐world data analysis. The developed technique possesses wide applicability to the systems and processes where the Cox PH model fits the reliability data well. Copyright © 2010 John Wiley & Sons, Ltd.
Multiresponse optimization using multivariate process capability index
Authors: Awad Mahmoud I. , Kovach Jamison V. 
Published: August 2010

AbstractRobust design is an efficient method for product and process improvement which combines experimentation with optimization to create a system that is less sensitive to uncontrollable variation. In this article, a simple and integrated modeling methodology for robust design is proposed. This methodology achieves the robustness objective function and input variables constraints simultaneously. The objective function is written in terms of the multivariate process capability vector (MCpm) of several competing features of the system under study. The proposed methodology is applicable to general functions of the system performance with random variables. The effectiveness of the methodology is verified using two real‐world examples which are compared with those of other robust design methods. Copyright © 2010 John Wiley & Sons, Ltd.
Observer‐based control of linear complementarity systems
Authors: Heemels W. P. M. H. , Camlibel M. K. , Schumacher J. M. , Brogliato B. 
Published: August 2010

AbstractIn this paper we present observer and output‐based controller design methods for linear complementarity systems (LCS) employing a passivity approach. Due to various inherent properties of LCS, such as the presence of state jumps, mode dynamics described by differential and algebraic equations (DAEs), and regions for certain modes being lower dimensional, various observer and control design schemes that have been proposed for other classes of (hybrid) dynamical systems do not apply to LCS. In particular, we present an observer design method for LCS which is effective even in the presence of state jumps. We show the well‐posedness of the observer, in the sense of existence and uniqueness of solution trajectories for the estimated state, and prove the global exponential stability of the observation error. These two properties guarantee that the estimated state exponentially recovers the state of the system. For the problem of stabilization based on output measurements only, we adopt an observer‐based control approach in which we apply a state feedback law to the estimated state obtained from the observer. We prove that the resulting closed‐loop system is well‐posed and globally exponentially stable. In order to show the well‐posedness of the closed loop, novel well‐posedness results for LCS based on low‐index properties are presented. Copyright © 2010 John Wiley & Sons, Ltd.
LMI optimization approach to robust decentralized controller design
Authors: Labibi Batool , Marquez Horacio Jose , Chen Tongwen 
Published: August 2010

AbstractA new approach for design of robust decentralized controllers for continuous linear time‐invariant systems is proposed using linear matrix inequalities (LMIs). The proposed method is based on closed‐loop diagonal dominance. Sufficient conditions for closed‐loop stability and closed‐loop block‐diagonal dominance are obtained. Satisfying the obtained conditions is formulated as an optimization problem with a system of LMI constraints. By adding an extra LMI constraint to the system of LMI constraints in the optimization problem, the robust control is addressed as well. Accordingly, the decentralized robust control problem for a multivariable system is reduced to an optimization problem for a system of LMI constraints to be feasible. An example is given to show the effectiveness of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd.
Nonsmooth µ‐synthesis
Authors: Apkarian Pierre 
Published: August 2010

AbstractWe revisit robust complex‐ and mixed‐ µ‐synthesis problems based on upper bounds and show that they can be recast as specially structured controller design programs. The proposed reformulations suggest a streamlined handling of µ‐synthesis problems using recently developed (local) nonsmooth optimization methods, where both scalings or multipliers and a controller of given structure are obtained simultaneously. A first cut of the nonsmooth programming software for structuredH∞synthesis is made available through the MATLAB R2010b Prerelease,Robust Control Toolbox Version 3.5developed by The MathWorks, Inc. Copyright © 2010 John Wiley & Sons, Ltd.
Switched state feedback for uncertain continuous‐time systems with interval delays
Authors: Mahmoud Magdi S. , Xia Yuanqing 
Published: August 2010

AbstractThe objective of this paper is to design a switched robust control for a class of continuous‐time systems subject to linear fractional uncertainty and interval time delays. The controller is based on state feedback and the LMI‐based stability conditions are derived using an improved Lyapunov–Krasovskii functional. Moreover, the switching rule as well as the state feedback gains are determined from the minimization of a guaranteed cost function. The theoretical results are illustrated with a numerical example. Copyright © 2010 John Wiley & Sons, Ltd.
Weighted Kaplan–Meier estimators for two‐stage treatment regimes
Authors: Miyahara Sachiko , Wahed Abdus S. 
Published: August 2010

AbstractIn two‐stage randomization designs, patients are randomized to one of the initial treatments, and at the end of the first stage, they are randomized to one of the second stage treatments depending on the outcome of the initial treatment. Statistical inference for survival data from these trials uses methods such as marginal mean models and weighted risk set estimates. In this article, we propose two forms of weighted Kaplan–Meier (WKM) estimators based on inverse‐probability weighting—one with fixed weights and the other with time‐dependent weights. We compare their properties with that of the standard Kaplan–Meier (SKM) estimator, marginal mean model‐based (MM) estimator and weighted risk set (WRS) estimator. Simulation study reveals that both forms of weighted Kaplan–Meier estimators are asymptotically unbiased, and provide coverage rates similar to that of MM and WRS estimators. The SKM estimator, however, is biased when the second randomization rates are not the same for the responders and non‐responders to initial treatment. The methods described are demonstrated by applying to a leukemia data set. Copyright © 2010 John Wiley & Sons, Ltd.
Regression analysis of clustered interval‐censored data with informative cluster size
Authors: Kim Yang‐Jin 
Published: August 2010

AbstractInterval‐censored data are commonly found in studies of diseases that progress without symptoms, which require clinical evaluation for detection. Several techniques have been suggested with independent assumption. However, the assumption will not be valid if observations come from clusters. Furthermore, when the cluster size relates to response variables, commonly used methods can bring biased results. For example, in a study on lymphatic filariasis, a parasitic disease where worms make several nests in the infected person's lymphatic vessels and reside until adulthood, the response variable of interest is the nest‐extinction times. As the extinction times of nests are checked by repeated ultrasound examinations, exact extinction times are not observed. Instead, data are composed of two examination points: the last examination time with living worms and the first examination time with dead worms. Furthermore, as Williamsonet al. (Statistics in Medicine2008;27:543–555) pointed out, larger nests show a tendency for low clearance rates. This association has been denoted as an informative cluster size. To analyze the relationship between the numbers of nests and interval‐censored nest‐extinction times, this study proposes a joint model for the relationship between cluster size and clustered interval‐censored failure data. A proportional hazard model with random effect and a mixed ordinal regression model are applied to failure times and cluster size, respectively. The joint model approach addresses both the association among failure times from the same cluster and the dependency of failure times on cluster size. Simulation studies are performed to assess the finite sample properties of the estimators and lymphatic filariasis data are analyzed as an illustration. Copyright © 2010 John Wiley & Sons, Ltd.
Sample size determination in step‐up testing procedures for multiple comparisons with a control
Authors: Kwong Koon Shing , Cheung Siu Hung , Wen Miin‐Jye 
Published: August 2010

AbstractStep‐up procedures have been shown to be powerful testing methods in clinical trials for comparisons of several treatments with a control. In this paper, a determination of the optimal sample size for a step‐up procedure that allows a pre‐specified power level to be attained is discussed. Various definitions of power, such as all‐pairs power, any‐pair power, per‐pair power and average power, in one‐ and two‐sided tests are considered. An extensive numerical study confirms that square root allocation of sample size among treatments provides a better approximation of the optimal sample size relative to equal allocation. Based on square root allocation, tables are constructed, and users can conveniently obtain the approximate required sample size for the selected configurations of parameters and power. For clinical studies with difficulties in recruiting patients or when additional subjects lead to a significant increase in cost, a more precise computation of the required sample size is recommended. In such circumstances, our proposed procedure may be adopted to obtain the optimal sample size. It is also found that, contrary to conventional belief, the optimal allocation may considerably reduce the total sample size requirement in certain cases. The determination of the required sample sizes using both allocation rules are illustrated with two examples in clinical studies. Copyright © 2010 John Wiley & Sons, Ltd.
A nonlinear model for highly unbalanced repeated time‐to‐event data: Application to labor progression
Authors: Arunajadai Srikesh G. 
Published: August 2010

AbstractThe collection of repeated measurements over time on an experimental unit to study the changes over time of a certain characteristic is common in biological and clinical studies. Data of this type are also often referred to as growth curve data or repeated measures data. There arise situations when one is interested in an estimate of the time to an event, based on a characteristic that indicates progression towards the event. The assessment of the progression of labor during childbirth based on cervical dilation is one such example. Here increase in the dilation of the cervix indicates progression towards delivery. Based on how long one has been in labor and an estimate of the time to complete dilation one might make crucial decisions like the decision to administer a drug or to perform a C‐section. Here a repeated measures approach is developed to model the time to the event. The parameters of the model are estimated by a maximum likelihood approach. A general model is developed for a class of data structures and a nonlinear model is developed specific to the labor progression data. Simulations are performed to assess the methodology and conditions are suggested for predicting the time to an event. Copyright © 2010 John Wiley & Sons, Ltd.
A systems approach to livability and sustainability: Defining terms and mapping relationships to link desires with ecological opportunities and constraints
Authors: Chazal Jacqueline de 
Published: August 2010

AbstractI offer a protocol for assessing the sustainability of livability. This protocol draws on a framework developed to assess vulnerability, and offers two key pertinent features. These are (a) a capacity to incorporate multiple and shifting stakeholder values and (b) a means of moving from expressions of livability to underlying ecological attributes that deliver or constrain system change. The applicability of these features to both assessing the sustainability of livability and a reappraisal given system change are illustrated using data from a study site in the French Alps. The central place of values intrudes into livability and sustainability so as to complicate the situation. Even so, the protocol presented here is able to ground the abstractions and equivocation in a transparent and explicit set of announcements. Laying the steps out in the open allows for consistency in comparison and replication without artificially removing the labile flexibility embedded in livability and sustainability. Copyright © 2010 John Wiley & Sons, Ltd.
Physicochemical and structural characteristics of cross‐linked banana starch using three cross‐linking reagents
Authors: Rodríguez‐Marín María L. , Núñez‐Santiago Carmen , Wang Ya‐Jane , Bello‐Pérez Luis A. 
Published: September 2010

AbstractBanana starch was cross‐linked using different cross‐linking reagents, phosphoryl chloride (POCl3), sodium trimetaphosphate (STMP), and epichlorohydrin (ECH), under alkaline conditions. The reaction conditions were selected to produce similar pasting profiles. The effects of the different cross‐linking reagents on the physicochemical and structural characteristics of cross‐linked starches were evaluated. The microscopy study did not show difference on the surface of the granules. Slight decrease in the peak temperature and enthalpy were found in the cross‐linked banana starch. The chemical groups introduced in the starch molecules by the diverse reagents promoted the re‐association of starch chains during storage. The rheological analysis of all starch dispersion at 10% (flow curves) showed a non‐Newtonian shear‐thinning; pastes obtained were time‐independent, suggesting an important contribution of the continuous phase. Structural study showed that the cross‐linked STMP‐starch had the lowest level of amylose and the ratio short/long amylopectin chains. The three reagents used for cross‐linking presented different action mode on starch granule and its components.
Gli1 Is an Inducing Factor in Generating Floor Plate Progenitor Cells from Human Embryonic Stem Cells
Authors: Denham Mark , Thompson Lachlan H. , Leung Jessie , Pébay Alice , Björklund Anders , Dottori Mirella 
Published: August 2010

Abstract
Generation of mesencephalic dopamine (mesDA) neurons from human embryonic stem cells (hESCs) requires several stages of signaling from various extrinsic and intrinsic factors. To date, most methods incorporate exogenous treatment of Sonic hedgehog (SHH) to derive mesDA neurons. However, we and others have shown that this approach is inefficient for generating FOXA2+ cells, the precursors of mesDA neurons. As mesDA neurons are derived from the ventral floor plate (FP) regions of the embryonic neural tube, we sought to develop a system to derive FP cells from hESC. We show that forced expression of the transcription factor GLI1 in hESC at the earliest stage of neural induction, resulted in their commitment to FP lineage. The GLI1+ cells coexpressed FP markers, FOXA2 and Corin, and displayed exocrine SHH activity by ventrally patterning the surrounding neural progenitors. This system results in 63% FOXA2+ cells at the neural progenitor stage of hESC differentiation. The GLI1-transduced cells were also able to differentiate to neurons expressing tyrosine hydroxylase. This study demonstrates that GLI1 is a determinant of FP specification in hESC and describes a highly robust and efficient in vitro model system that mimics the ventral neural tube organizer.
Defining the fetal cardiac axis between 11 + 0 and 14 + 6 weeks of gestation: experience with 100 consecutive pregnancies
Authors: Sinkovskaya E. , Horton S. , Berkley E. M. , Cooper J. K. , Indika S. , Abuhamad A. 
Published: September 2010

AbstractObjectiveThe purpose of this study was to establish normal fetal cardiac axis values during the first and early second trimesters of pregnancy.MethodsThis was a prospective observational cohort study in which the fetal cardiac axis was assessed during ultrasound examinations in 100 consecutive fetuses between 11 + 0 and 14 + 6 weeks of gestation. Transabdominal, and, when indicated, transvaginal, approaches were used. Intraobserver and interobserver reproducibility were calculated.ResultsThe cardiac axis ranged from 34.5 to 56.8° (mean (SD) 47.6 ± 5.6°) in 94 fetuses with normal cardiac anatomy. The fetal cardiac axis tended to be significantly higher in fetuses at 11 + 0 to 11 + 6 weeks of gestation than in fetuses at 12 + 0 to 14 + 6 weeks of gestation. Congenital heart defects were found in six out of 100 fetuses, four of which had abnormal cardiac axis values at 11 + 0 to 14 + 6 weeks of gestation.ConclusionCardiac axis measurement is possible in the first and early second trimesters of pregnancy. The assessment of cardiac axis at an early gestational age may help to identify pregnancies at high risk for congenital heart defects. Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.