bluuebunny/crossref_metadata_2025_split huggingface dataset:
The two peaks G′ band in carbon nanotubes
Authors: Maciel Indhira O. , Pimenta Marcos A. , Terrones Mauricio , Terrones Humberto , Campos‐Delgado Jessica , Jorio Ado 
Published: September 2008

AbstractIn this work we discuss the nature of the extra peak that appears in the low frequency side the G′ band in the Raman spectra of single wall and double wall carbon nanotubes. This peak has been reported in many articles assigned as either the G′ band from small diameter nanotubes or the response for fulfilment of resonance conditions with incident and scattered light.Here we show that this peak is present in the Raman spectra independently on the diameter distribution of the sample and disappears after heat treatment. We believe the lower frequency component of the two‐peaks G′ band in carbon nanotubes is related to the presence of defects in the carbon nanotube structure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MoSIx connectivity in self‐assembled networks
Authors: Strle Jure , Vengust Damjan , Ploscaru Mihaela , Uplaznik Marko , Mihailović Dragan 
Published: September 2008

AbstractWe report on a new highly reproducible route to recognitive self‐assembly of molecular‐scale circuits using sulfur‐terminated subnanometer diameter Mo6S9–x Ix (MoSIx) molecular nanowires.We demonstrate solutionprocessed attachment of MoSIx connecting leads to gold nanoparticles (GNPs). We also show that naked nanowires have the potential to bind thiolated proteins such as green fluorescent protein directly, thus providing a universal construct to which almost any protein could be attached.We further demonstrate three‐terminal branched circuits with GNPs, opening a self‐assembly route to multiscale complex molecular‐scale architectures at the single‐molecule level. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bonding environment and electronic structure of Gd metallofullerene and Gd nanowire filled single‐wall carbon nanotubes
Authors: Pichler T. , Kramberger C. , Ayala P. , Shiozawa H. , Knupfer M. , Rümmeli M. H. , Batchelor D. , Kitaura R. , Imazu N. , Kobayashi K. , Shinohara H. 
Published: September 2008

AbstractBeing single‐walled carbon nanotubes, archetypical 1D systems with peculiar anisotropic electronic properties, it is possible to infer modifications in a controlled manner by filling their inner hollow space. One successful approach was proposed for Gd, which regards filling with metallofullerenes and a successful transformation into different novelmetal nanowires by a versatile nanochemical reaction. In this contribution we report on a combined high resolution photoemission and X‐ray absorption study on Gd@C82 peapods and Gd nanowires.From a detailed analysis of the Gd 4d response and the valence band in photoemission we are able to elucidate the changes in the bonding environment and charge transfer in these 1D systems. We observe a clear modification of the low energy electronic properties of the SWCNT by the filling with Gd nanowires. Our findings provide important input to understand the interplay between charge transfer and hyridisation in the nanochemical processes in these hybrid systems and to elucidate their electronic transport properties regarding their application potential in nanoelectronic devices. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electron spin resonance in alkali doped SWCNTs
Authors: Simon F. , Galambos M. , Quintavalle D. , Náfrádi B. , Forró L. , Koltai J. , Zólyomi V. , Kürti J. , Nemes N. M. , Rümmeli M. H. , Kuzmany H. , Pichler T. 
Published: September 2008

AbstractElectron spin resonance (ESR) measurements on SWCNTs doped with alkali atoms (potassium) using a solid state reaction is reported. We find the emergence of the ESR signal of itinerant electrons upon doping with a signal intensity that is comparable to that expected from band structure calculations.The ESR line‐width and microwave conductivity weakly depend on the temperature indicating that doped SWCNTs are bad metals. It is argued to result from the lack of crystalline order in the tubes and the large impurity concentration. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phonon dispersion of small diameter semiconducting chiral carbon nanotubes – a theoretical study
Authors: Koltai János , Zólyomi Viktor , Kürti Jenő 
Published: September 2008

AbstractWe present first principles calculations on the phonon dispersion of a large number of small diameter chiral single walled carbon nanotubes. The use of density functional theory for unit cells containing hundreds of atoms was only possible because the helical symmetry was taken into account explicitly in our frequency calculations.The results can be useful for interpretation of experiments, especially on CoMoCat tubes, but also on HiPCo tubes and the inner walls of double walled carbon nanotubes. The phonon dispersions of several larger diameter tubes have also been calculated for comparison. A clear phonon softening with decreasing diameter has been observed for the D and D*‐bands. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High frequency electron spin resonance study of peapods
Authors: Olariu A. , Náfrádi B. , Ćiri ć L. , Nemes N. M. , Forró L. 
Published: September 2008

AbstractWe present high frequency Electron Spin Resonance (ESR) results on a peapod sample. In a previous low frequency ESR study on peapods and double‐walled nanotubes the observation of a non‐Lorentzian line shape was reported. This effect was tentatively attributed to the presence of two distinct Lorentzian signals, coming from the outer tube and from the inner tube or from fullerenes. Here we report ESR measurements in a broad frequency (and magnetic field) range, which help to resolve this uncertainty. Since, with increasing magnetic field, no splitting of the line is observed, just a linear increase with frequency, we attribute the non‐Lorentzian shape to g ‐factor distribution. The extracted line width weakly increases with temperature. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability and electronic properties of magnetic peapods
Authors: Tóth S. , Quintavalle D. , Náfrádi B. , Forró L. , Korecz L. , Rockenbauer A. , Kálai T. , Hideg K. , Simon F. 
Published: September 2008

AbstractWe report on the temperature stability of N@C60 peapods using electron spin resonance. The atomic nitrogen escapes at higher temperatures in the peapod than in the crystalline form. We also report on the synthesis of novel magnetic fullerene peapod, a fullerene with an attached pyridine‐nitroxide spin‐label. This molecule can be the ultimate inner spin label for the SWCNTs as it is available in microscopic amounts and is not air sensitive. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of a ZnS‐shell on the structural and electronic properties of CdSe‐nanorods
Authors: Mohr M. , Thomsen C. 
Published: September 2008

AbstractCdSe nanorods were studied via density functional theory calculations. The influence of a ZnS shell on the structural and electronic propertieswas investigated. The ZnS shell leads to a shortening of the CdSe bond length, the magnitude depending on the bond length orientation with respect to the axis. The electronic band gap is reduced by the presence of the ZnS shell. In the present study, the CdSe/ZnS multistructure forms a type II heterojunction, in contrast to plane CdSe/ZnS superlattices. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unsteady exact solutions of the flow equations for three‐dimensional spherical atmospheres
Authors: Staniforth A. , White A. A. 
Published: September 2008

AbstractTime‐dependent, closed‐form solutions of the 3D Euler equations describing motion relative to a uniformly rotating coordinate frame are derived. The spherical geopotential approximation is applied but not the shallow‐atmosphere and hydrostatic approximations. The solutions correspond to cyclostrophically and hydrostatically balanced vortices that are steady in inertial space and whose symmetry axes do not coincide with the rotation axis of the coordinate frame. The inertial‐frame flow velocities are readily transformed to a precisely spherical rotating coordinate system in which the 3D Euler equations contain centrifugal as well as Coriolis terms. In this form the solutions may be used to test numerical models formulated in spherical coordinates under the spherical geopotential approximation, so long as the centrifugal terms are explicitly included as forcing terms. The development is repeated for the hydrostatic and non‐hydrostatic primitive equations (with the shallow‐atmosphere approximation) and for the shallow‐water equations. In the latter case, the required explicit centrifugal force may be provided by a zonally symmetric addition to the free surface height, with an identically equal orographic elevation to ensure conservation of mass. The solutions are then identical to the unsteady shallow‐water solutions of Läuter et al. that inspired this study. ©Crown Copyright 2008. Reproduced with the permission of the Controller of HMSO and the Queen's Printer for Scotland. Published by John Wiley & Sons, Ltd.
Robust attitude tracking control of flexible spacecraft for achieving globally asymptotic stability
Authors: Erdong Jin , Zhaowei Sun 
Published: September 2008

AbstractThe three‐axis attitude tracking control problem in the presence of parameter uncertainties and external disturbances for a spacecraft with flexible appendages is investigated in this paper. Novel simple robust Lyapunov‐based controllers that require only the attitude and angular velocity measurement are proposed. The first controller is a discontinuous one composed of a nonlinear PD part plus a sign function, whereas the second one is continuous or even smooth by modifying the discontinuous part of the first one. For a general desired trajectory, both controllers can achieve globally asymptotic stability of the attitude and angular velocity tracking errors instead of ultimate boundedness. By using a two‐step proof technique, the partial stability of the proposed controllers for the resulting closed‐loop systems in the face of model uncertainties and unexpected disturbances is proven theoretically. To further enhance the control performance, a continuous controller is presented that utilizes the tracking errors for estimating the external disturbances. In addition, stability analysis is done. For all the developed controllers, numerical simulation results are provided to demonstrate their performance. Copyright © 2008 John Wiley & Sons, Ltd.
Robust ℒ︁2‐gain feedforward control of uncertain systems using dynamic IQCs
Authors: Köse I. E. , Scherer C. W. 
Published: September 2008

AbstractWe consider the problem of robust ℒ︁2‐gain disturbance feedforward control for uncertain systems described in the standard LFT form. We use integral quadratic constraints (IQCs) for describing the uncertainty blocks in the system. For technical reasons related to the feedforward problem, throughout the paper, we work with the duals of the constraints involved in robustness analysis using IQCs. We obtain a convex solution to the problem using a state‐space characterization of nominal stability that we have developed recently. Specifically, our solution consists of LMI conditions for the existence of a feedforward controller that guarantees a given ℒ︁2‐gain for the closed‐loop system. We demonstrate the effectiveness of using dynamic IQCs in robust feedforward design through a numerical example. Copyright © 2008 John Wiley & Sons, Ltd.
Assessment and prioritization of eco‐revetment projects in urban rivers
Authors: Shi Rui‐Hua , Xu Shi‐Guo , Li Xu‐Guang 
Published: September 2008

AbstractEcological revetment for slope protection in urban rivers requires consideration of economic and ecological aspects and also of social aspects including recreation. Taking the Hunhe River as an example, our study established an evaluation system and a decision‐making method for evaluating and prioritizing the eco‐revetment projects. The Delphi method was used for collecting the opinions of experts, which include the relative importance of the indicators and the relative preference of the alternatives. The former was surveyed by pair comparison and processed applied analytic hierarchy process (AHP). The latter was described via linguistic variables, which need to be changed into the quantitative values for TOPSIS analysis. For that reason, we introduced the fuzzy set theory and established a fuzzy multi‐attribute decision‐making method based on TOPSIS to assess and prioritize the projects. The evaluation system includes economic, social, environment and ecological several aspects totalling eight indicators. The evaluating and prioritizing result of the projects shows that the three‐dimensional vegetation net is the best slope protection measures in the study area. The sensitivity analyses of indicator weights and different calculation methods were performed to demonstrate the reliability of the results. The sensitivity analyses indicate that construction cost and maintenance cost are dominant factors during the alternatives prioritization. The distance calculation method and normalization technique are insensitive to the prioritization results. The methodology proposed by this paper offers an effective and feasible tool for managers to evaluate and choose the optimal engineering measures of riverbank protection. Copyright © 2008 John Wiley & Sons, Ltd.
The influence of fluctuating ramping rates on the food web of boreal rivers
Authors: Marty Jérôme , Smokorowski Karen , Power Michael 
Published: September 2008

AbstractA BACI (before‐after‐control‐impact) sampling design was applied to determine the possible effects of ramping rate (RR) regulation on food webs structure and function in a regulated boreal river. We used carbon and nitrogen stable isotope signatures of primary producers, macroinvertebrates and fish to determine variations in the source of carbon fuelling the food web as well as changes in the food web structure under variable RR flow regime. We hypothesized that unrestricted RR would (1) increase the connectivity between terrestrial and aquatic environments allowing for a higher contribution of terrestrial carbon to support the food web and (2) decrease food web length because of frequent disturbances. Unrestricted RR had little influence on δ13C values for the overall food web with most of the differences found between impacted sites compared and control sites, indicating that the proportion of various carbon sources entering the diet of consumers remained unchanged under unrestricted RR. In contrast, significantly higher δ15N values were measured in impacted sites (invertebrates and fish) and as well as under unrestricted ramping flow regime (invertebrates). Further, unrestricted RR was associated to a significant decrease in the difference between macroinvertebrates and fish δ15N signatures, equivalent to a reduction of the length of the food web by at least one trophic level. Results from this study indicate that RR should be taken into consideration in the regulation of operating regimes on rivers. Copyright © 2008 John Wiley & Sons, Ltd.
Influences of flooding and hyporheic exchange on floodplain plant richness and productivity
Authors: Mouw Jason E. B. , Stanford Jack A. , Alaback Paul B. 
Published: September 2008

AbstractFlooding disturbance and associated fluvial processes are generally thought to be the primary controls on floodplain species richness patterns. We expanded this idea to include ground and surface water (hyporheic) exchange within alluvial flood plains. At the floodplain scale, we hypothesized that upwelling areas would be richer in species and support higher growth rates of woody plants. At reaches within each flood plain, we evaluated the mechanisms of flood duration, patterns in sedimentation and driftwood as influences. We found patterns of species richness within the shifting mosaic of floodplain wetland habitats to be incoherent with flood duration for large flood plains on the Flathead and Talkeetna Rivers. Rather, species richness was closely associated with hyporheic exchange at the floodplain scale and locally with alluvial particle size. Species richness was highest in areas of both flood plains characterized by upwelling groundwater. On annually scoured surfaces, richness was affected by large wood debris that reduced flow competence, allowing fine sediment deposition and plant establishment. Richness within upwelling and downwelling reaches was highest at sites with the finest alluvia.Growth rates of woody species used as indices of site productivity were also significantly higher at areas characterized by upwelling. We concluded that plant species richness was strongly controlled by hyporheic exchange at the floodplain scale and locally by the deposition of fine alluvia. This interpretation was not consistent with intermediate levels of flood disturbance. Indeed, areas of the flood plain least influenced by flow energy had the highest richness on both flood plains. Copyright © 2008 John Wiley & Sons, Ltd.
Inference for cumulative incidence functions with informatively coarsened discrete event‐time data
Authors: Shardell Michelle , Scharfstein Daniel O. , Vlahov David , Galai Noya 
Published: September 2008

AbstractWe consider the problem of comparing cumulative incidence functions of non‐mortality events in the presence of informative coarsening and the competing risk of death. We extend frequentist‐based hypothesis tests previously developed for non‐informative coarsening and propose a novel Bayesian method based on comparing a posterior parameter transformation with its expected distribution under the null hypothesis of equal cumulative incidence functions. Both methods use estimates derived by extending previously published estimation procedures to accommodate censoring by death. The data structure and analysis goal are exemplified by the AIDS Link to the Intravenous Experience (ALIVE) study, where researchers are interested in comparing incidence of human immunodeficiency virus seroconversion by risk behavior categories. Coarsening in the forms of interval and right censoring and censoring by death in ALIVE is thought to be informative; thus, we perform a sensitivity analysis by incorporating elicited expert information about the relationship between seroconversion and censoring into the model. Copyright © 2008 John Wiley & Sons, Ltd.
The type I error and power of non‐parametric logrank and Wilcoxon tests with adjustment for covariates—A simulation study
Authors: Jiang Honghua , Symanowski James , Paul Sofia , Qu Yongming , Zagar Anthony , Hong Shengyan 
Published: September 2008

AbstractTime‐to‐event outcomes are common for oncology clinical trials. Conventional methods of analysis for these endpoints include logrank or Wilcoxon tests for treatment group comparisons, Kaplan–Meier survival estimates, and Cox proportional hazards models to estimate the treatment group hazard ratio (both unadjusted and adjusted for relevant covariates). Adjusting for covariates reduces bias and may increase precision and power (Statist. Med.2002;21:2899–2908). However, the appropriateness of the Cox proportional hazards model depends on parametric assumptions. One way to address these issues is to use non‐parametric analysis of covariance (J. Biopharm. Statist.1999;9:307–338). Here, we carry out simulations to investigate the type I error and power of the unadjusted and covariate‐adjusted non‐parametric logrank test and Wilcoxon test, and the Cox proportion hazards model. A comparison between the covariate‐adjusted and unadjusted methods is also illustrated with an oncology clinical trial example. Copyright © 2008 John Wiley & Sons, Ltd.
EWMA smoothing and Bayesian spatial modeling for health surveillance
Authors: Zhou Huafeng , Lawson Andrew B. 
Published: September 2008

AbstractIn this paper a novel method for the monitoring of disease maps over time in a surveillance setting is described. The approach relies upon the use of a spatial model that is fitted to current spatial data and is smoothed with historical spatial estimates. The method of smoothing is a vector exponentially weighted moving average procedure. A simulation study with a range of scenarios is presented and finally a case study of monitoring infectious disease spread is presented. Copyright © 2008 John Wiley & Sons, Ltd.
Statistical epidemic modeling with hospital outbreak data
Authors: Wolkewitz M. , Dettenkofer M. , Bertz H. , Schumacher M. , Huebner J. 
Published: September 2008

AbstractThe analysis of epidemic data has one special feature: individuals are highly dependent, i.e. infected cases are the cause of further infected cases (cross‐infection). The main epidemiological parameter of interest is the transmission rate: the rate with which an infectious individual has close contacts with other patients in the hospital unit resulting in colonization or infection. In order to estimate this parameter, the statistical analysis should be based on an appropriate compartmental model that describes the transmission dynamics of an epidemic process. Nonparametric methodology is available for closed populations without migration, but especially in hospitals, admission and discharge have to be taken into account in addition. Transmission and discharge have to be considered as competing events. Martingale‐based methodology takes the time‐dependent feature of the rates adequately into account and yields useful estimates. These methods are applied to an outbreak of the specific hospital pathogen vancomycin‐resistant enterococci (VRE) in an onco‐haematological unit at the University Medical Center Freiburg in Germany. Copyright © 2008 John Wiley & Sons, Ltd.
Weighted statistics for aggregation and linkage analysis of human longevity in selected families: The Leiden Longevity Study
Authors: Houwing‐Duistermaat J. J. , Callegaro A. , Beekman M. , Westendorp R. G. , Slagboom P. E. , van Houwelingen J. C. 
Published: September 2008

AbstractTypically long‐lived sibling pairs have been collected for linkage analysis of human longevity and information on life span of first‐degree relatives is available to assess familial aggregation of life span. We propose a new weighted statistic for aggregation analysis, which tests for a relationship between a family history of excessive survival of the sibships of the long‐lived pairs and the survival of their parents and their offspring. For linkage analysis, we derive a new weighted score statistic from a simple gamma frailty model, which assigns more weight to excessive long‐lived pairs. We apply the methods to data from the Leiden Longevity Study, which consists of sibling pairs of age 90 years or above and their first‐degree relatives. The pairs have been genotyped for microsatellite markers in a candidate region. Association was present between survival within the sibships and survival of the offspring, but not with the parental generation. For linkage analysis, weighting increased the value of the test statistic, but the result was not statistically significant. About the methods we conclude that the statistic for aggregation provides insight into clustering of life span and the statistic for linkage provides a new tool to include demographic information into the analysis. Copyright © 2008 John Wiley & Sons, Ltd.