bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of tantalum dopant ions (Ta5+) on the efficiency of the tungsten trioxide photoelectrode
Authors: Enesca A. , Duta A. , Schoonman J. 
Published: July 2008

AbstractThe paper presents the influence of the tantalum dopant ions (Ta5+) on the properties of WO3 film, used as photoelectrode for water photolysis. The photoluminescence and photocurrent stability were recorded in a photoelectrochemical system having doped and, respectively, undoped WO3 films, deposited by spray pyrolysis on fluorine–doped tin oxide as photoanode and Pt as cathode, in electrolyte HCl (pH = 5). The crystalline structure, topography and electrical properties were investigated. The experiments confirm that the doping process double the photoelectrode efficiency. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mosaicity and stress effects on luminescence properties of GaN
Authors: Toure A. , Bchetnia A. , Lafford T. A. , Benzarti Z. , Halidou I. , Bougrioua Z. , Jani B. El 
Published: July 2008

AbstractHigh‐resolution X‐ray diffraction (HRXRD) of several GaN layers grown on Si/N treated c ‐plane sapphire substrate by metal‐organic chemical vapour phase deposition (MOCVD) were investigated. Photoluminescence (PL) measurements were carried out at 13 K. GaN mosaicity was studied at different growth stage with a thickness varying from 0.1 to 4.5 µm. Rocking curves of symmetric and asymmetric plane reflections were investigated to determine respectively the tilt and twist mosaic. Using PL spectra and HRXRD scattering a correlation were found between the intensity and the full width at half maximum (FWHM) of the bound exciton neutral donor (I2) with the GaN mosaicity. The I2 intensity increased significantly with increasing the interaction parameter (m) between tilt and twist mosaic, whereas the FWHM of I2 decreased with increasing m. The evolution of the compressive stress with thickness is extracted from HRXRD and correlated with PL measurements. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interdiffusion in SiGe alloys with Ge contents of 25% and 50% studied by X‐ray reflectivity
Authors: Medunˇa M. , Novák J. , Bauer G. , Falub C. V. , Grützmacher D. 
Published: July 2008

AbstractThe interdiffusion in SiGe alloys has been studied by X‐ray specular reflectivity using ex‐situ and in‐situ annealing experiments. We report on the evolution of the Ge profile of strain‐compensated Si/SiGe multilayers due to high temperature annealing. These multilayers were grown pseudomorphically and strain‐symmetrized on relaxed Si0.75Ge0.25 and Si0.5Ge0.5 pseudosubstrates by molecular beam epitaxy at 330 °C. The multilayer structures were annealed at several temperatures around 590 °C and around 800 °C. From modelling the X‐ray specular reflectivity scans at various stages of the interdiffused structures, we obtained interdiffusion coefficients resulting in the activation energy and the prefactor for interdiffusion corresponding to Si0.75Ge0.25 and Si0.5Ge0.5. The results obtained ex‐situ for Si0.5Ge0.5 and in‐situ for Si0.75Ge0.25 provide accurate values of diffusion parameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
One‐step electrochemical deposition of CuInSe2 absorber layers
Authors: Kois J. , Volobujeva O. , Bereznev S. 
Published: July 2008

AbstractA new modified approach for the thermodynamics and kinetics constituents of the electrodeposition mechanism of CuInSe2 is presented. It is shown that the mechanism of CuInSe2 phase formation includes a number of consecutive reactions. Under the conditions of the one‐step electrochemical deposition process, the formation of Cu+Se phases are controlled by the diffusion of selenium and copper species, the insertion of indium into the film depends on the applied potential. The paper describes developed associated model used to determine the fluxes of copper, indium and selenium species to the cathode and relative concentrations of deposited solid phases. The distribution diagram of the final products in depending on applied potential and composition ratio of Se(IV)/Cu(II) in solution is build by the results of computations. The morphology of electrodeposited films is determined by the potential of deposition and the rate of mass transport in solution. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Decoupling crystalline volume fraction and VOC in microcrystalline silicon pin solar cells by using a µc‐Si:F:H intrinsic layer
Authors: Zhang Q. , Johnson E. V. , Djeridane Y. , Abramov A. , Cabarrocas P. Roca i 
Published: July 2008

AbstractMicrocrystalline silicon thin film pin solar cells with a highly crystallized intrinsic μc‐Si:F:H absorber were prepared by RF‐plasma enhanced chemical vapour deposition using SiF4 as the gas precursor. The cells were produced with a vacuum break between the doped layer and intrinsic layer depositions, and the effect of different subsequent interface treatment processes was studied. The use of an intrinsic μc‐Si:H p/i buffer layer before the first air break increased the short circuit current density from 22.3 mA/cm2 to 24.7 mA/cm2. However, the use of a hydrogen‐plasma treatment after both air breaks without an interface buffer layer improved both the open circuit voltage and the fill factor. Although the material used for the absorber layer showed a very high crystalline fraction and thus an increased spectral response at long wavelengths, an open‐circuit voltage (VOC) of 0.523 V was nevertheless observed. Such a value of VOC is higher than is typically obtained in devices that employ a highly crystallized absorber as reported in the literature (see abstract figure). Using a hydrogen‐plasma treatment, a single junction μc‐Si:F:H pin solar cell with an efficiency of 8.3% was achieved.magnified image(© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mountain torques and synoptic systems in the Mediterranean
Authors: Egger Joseph , Hoinka Klaus‐Peter 
Published: July 2008

AbstractThe mountains surrounding the Mediterranean exert torques T during the passage of North Atlantic systems which affect the angular momentum of the airflow passing over and around the massifs. The Alps, the Atlas range and the orographic block of Asia Minor are selected to investigate the typical flow conditions during torque events. These mountain ranges are small enough to justify a local angular momentum analysis. Both the zonal and the meridional components of a mountain's torque (Tλ and Tφ) are used as stratification parameters in a statistical investigation of the interaction of large‐scale perturbations with this mountain. How are these flows affected by the obstacle? A simple scheme is tested which attempts to interpret results.The torque analysis singles out eastward‐moving large‐scale systems. Their isobars are oriented from southwest (northwest) to northeast (southeast) near the mountain in zonal torque Tλ (Tφ) cases. The massifs tend to generate a low‐level distortion of the pressure field such that the angular momentum of the flow over the mountain is reduced. These results can be explained within the framework of the scheme. The influence of the mountains on the pressure field is seen only at heights ≤4000 m. The low‐level distortions of the pressure field contribute positively to the total torque for lags τ≤0 in the Alps and for all lags − 2≤τ≤2 days in Asia Minor, where only Tλ is evaluated. The impact of the Atlas mountains is seen only at τ = 0. Copyright © 2008 Royal Meteorological Society
Axisymmetric, nearly inviscid circulations in non‐condensing radiative‐convective atmospheres
Authors: Caballero Rodrigo , Pierrehumbert Raymond T. , Mitchell Jonathan L. 
Published: July 2008

AbstractWe study the steady‐state axisymmetric circulation of nearly inviscid, compressible atmospheres with no condensible component. Assuming simplified non‐grey radiative transfer and instantaneous adjustment to convective neutrality, we present an analytical theory for the depth, width and strength of the Hadley cell in terms of the planetary radius and rotation rate, insolation, optical depth and atmospheric composition. Under equatorially symmetric insolation, the Hadley cell width predicted by the present theory is generally very close to the Boussinesq, Newtonian cooling result of Held and Hou. We also introduce a new scaling theory for Hadley cell width under solstitial insolation conditions. The theory compares favourably with axisymmetric numerical results and also with full general‐circulation model simulations of Mars and Snowball Earth. Copyright © 2008 Royal Meteorological Society
Dependence of vortex axisymmetrization on the characteristics of the asymmetry
Authors: Peng Jiayi , Peng Melinda S. , Li Tim 
Published: July 2008

AbstractThis study investigates how different characteristics of initial asymmetries, including their positions and profiles, can impact on the vortex axisymmetrization process for barotropic vortices. When an initial disturbance is placed near the core of a vortex, a new asymmetry is generated inside the original asymmetry and grows due to its upshear tilt. Differential basic‐state rotation then shifts the phase to a downshear tilt and the asymmetry weakens. As the initial radius of the imposed asymmetry is increased, the initial upshear tilt of the asymmetry decreases. There is also a decrease in the efficiency with which the differential rotation shifts the phase tilt from upshear to downshear. The latter is related to differential radial propagation of the asymmetry in the form of vortex Rossby waves. These two mechanisms that are position‐dependent act against each other. There is an optimal radius at which the energy exchange between the symmetric and asymmetric flows is maximized. For a range of very different basic‐state profiles examined here, the optimal radius is around 1.5 to 2 times the radius of the maximum wind. The initial growth of asymmetries with higher azimuthal wavenumbers is weaker than their lower‐wavenumber counterparts due to a smaller upshear phase tilt with their smaller azimuthal length‐scales.Nonlinearity reduces the magnitude and multiple perturbations of the newly induced inner asymmetry, and also limits the radial propagation of the asymmetry. The further the asymmetry is away from the core, the slower the axisymmetrization is. Depending on the position of the initial asymmetry, the basic state can have an increase of the maximum wind, a double‐peak profile, or an increase of its outer wind profile through axisymmetrization. Copyright © 2008 Royal Meteorological Society
(E)‐4‐Alkoxycarbonylalkylthiochalcones: differentiation of isomeric derivatives by electron ionization mass spectrometry
Authors: Nowakowska Zdzisława , Pankiewicz Radosław 
Published: July 2008

AbstractThe principal fragmentation pathways of the molecular ions of 18 new (E)‐4‐alkoxycarbonylalkylthiochalcones have been investigated. It has been shown that the data derived from electron ionization mass spectra (the relative abundance of the fragment ions and values of coefficients µ) can be used to differentiate the isomers. The fragmentation rules deduced here could help in the characterization of other chalcones of these types. Copyright © 2008 John Wiley & Sons, Ltd.
Profiling of yew hair roots from various species using ultra‐performance liquid chromatography/electrospray ionization mass spectrometry
Authors: Ge Guang‐Bo , Luan Hong‐Wei , Zhang Yan‐Yan , He Yu‐Qi , Liu Xing‐Bao , Yang Li , Wang Zheng‐Tao , Yang Ling 
Published: July 2008

AbstractAn efficient and sensitive profiling approach to complex yew samples was developed using ultra‐performance liquid chromatography/electrospray ionization mass spectrometry (UPLC/ESI‐MS). The UPLC‐based method displayed short analytical time and improved peak capability, as well as high sensitivity. The appropriate in‐source collision‐induced dissociation (CID) energy was employed to produce informative characteristic ions which could be used for stereochemical and sub‐structural assignment of yew constituents. The method was successfully applied in the rapid screening of yew hair roots from various species, and 53 constituents including 47 taxoids were detected from partially purified root extract. Notably, C‐7 hydroxytaxane stereoisomers could be identified based on their different fragment ions under the optimal profiling conditions. It was also observed that hair roots from different Taxus species exhibited nearly identical chemical distribution, indicating they had similar metabolic frameworks. Additionally, Taxus root resources also display benign medicinal perspective because they have relatively simple chemical profiles and possess high yields of valuable taxanes such as paclitaxel, cephalomannine, 10‐deacetylpaclitaxel and 7‐xylosyltaxanes. Copyright © 2008 John Wiley & Sons, Ltd.
High‐throughput approaches towards the definitive identification of pharmaceutical drug metabolites. 1. Evidence for an ortho effect on the fragmentation of 4‐benzenesulfinyl‐3‐methylphenylamine using electrospray ionisation mass spectrometry
Authors: Holman Stephen W. , Wright Patricia , Langley G. John 
Published: July 2008

AbstractA 50 m/z unit loss from protonated 4‐benzenesulfinyl‐3‐methylphenylamine has been observed and investigated using electrospray ionisation quadrupole ion trap mass spectrometry (ESI‐QIT‐MS). It was hypothesised that the specific fragmentation was affected by the presence of an ortho methyl group in relation to the sulfoxide functionality, i.e. an ortho effect influences the preferred dissociation pathway. This was because the des‐methyl homologue did not display a 50 m/z unit loss. This fragmentation was shown to be a two‐step process with sequential losses of a hydroxyl radical and a thiol radical. Molecular modelling calculations showed that the most favourable site of protonation for 4‐benzenesulfinyl‐3‐methylphenylamine was the sulfoxide oxygen, which would facilitate the loss of a hydroxyl radical. Subsequent deuterium‐exchange experiments confirmed that the loss was a hydroxyl radical and afforded definitive assignment of the site of protonation. Furthermore, the involvement of a single exchangeable hydrogen atom in the overall 50 m/z unit loss was demonstrated. Thus, supportive evidence was provided for the involvement of the ortho methyl group in the second stage of the fragmentation, leading to the loss of the thiol radical. Accurate mass measurements, performed using electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry (ESI‐FTICR‐MS), verified the elemental formulae of the individual losses. The ion structure following the 50 m/z unit loss was proposed to be a protonated aminofluorene and was supported by comparing the product ion spectrum of commercially available protonated 2‐aminofluorene with the MS4 data of protonated 4‐benzenesulfinyl‐3‐methylphenylamine. Fragmentation mechanisms are proposed. The relevance of the loss with regards to pharmaceutical drug metabolite identification is discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Robotic appendectomy in gynaecological surgery: technique and pathological findings
Authors: Akl Mohamed N. , Magrina Javier F. , Kho Rosanne M. , Magtibay Paul M. 
Published: July 2008

AbstractBackgroundWe evaluated the feasibility, safety and pathological findings of incidental robotic appendectomy in patients undergoing robotic gynaecological surgery.MethodsRetrospective analysis of 107 consecutive cases of robotic appendectomy done in conjunction with other robotic gynaecological procedures between May 2004 and January 2007.ResultsAll appendectomies were performed robotically in conjunction with other robotic procedures. Mean time for appendectomy was 3.4 min. No perioperative complications related to appendectomy were encountered. Among 90 patients with no gynaecological malignancy, 57 patients reported chronic pelvic pain preoperatively and 21 (37%) of them had an abnormal appendiceal pathology as compared to only 5 (15%) of the 33 patients with no pelvic pain (OR. 3.2; 95% CI, 1.1–9.7, p = 0.032). Of seven patients with ovarian malignancy, three (42%) had appendicular metastasis.ConclusionIncidental robotic appendectomy can be performed safely without the need for switching to conventional laparoscopy. It should be considered in patients undergoing robotic pelvic surgery for pelvic pain and ovarian malignancy. Copyright © 2008 John Wiley & Sons, Ltd.
More efficient queries in PCPs for NP and improved approximation hardness of maximum CSP
Authors: Engebretsen Lars , Holmerin Jonas 
Published: July 2008

AbstractSamorodnitsky and Trevisan [STOC 2000, pp. 191–199] proved that there exists, for every positive integerk, a PCP forNPwithO(logn) randomness, query complexity 2k+k2, free bit complexity 2k, completeness 1 ‐ϵ, and soundness 2+ϵ. In this article, we devise a new “outer verifier,” based on the layered label cover problem recently introduced by Dinur et al. [STOC 2003, pp. 595–601], and combine it with a new “inner verifier” that uses the query bits more efficiently than earlier verifiers. Our resulting theorem is that there exists, for every integerf≥ 2, every positive integert≤f(f‐ 1)/2, and every constantϵ> 0, a PCP forNPwithO(logn) randomness, query complexityf+t, free bit complexityf, completeness 1 ‐ϵ, and soundness 2‐t+ϵ. As a corollary, there exists, for every integerq≥ 3 and every constantϵ> 0, aq‐query PCP forNPwith amortized query complexity 1 +$ 1 + \sqrt{2/q} + \varepsilon $+ϵ. This improves upon the result of Samorodnitsky and Trevisan with respect to query efficiency, i.e., the relation between soundness and the number of queries. Although the improvement may seem moderate—the construction of Samorodnitsky and Trevisan has amortized query complexity 1 + 2/$ 1 + 2/\sqrt{q} + \varepsilon $—we also show in this article that combining our outer verifier with any natural candidate for a corresponding inner verifier gives a PCP that is less query efficient than the one we obtain.© 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2008
An overview of the Sirius satellite radio system
Authors: Akturan Riza 
Published: July 2008

AbstractThis paper presents the system architecture and expected link availability for the Sirius satellite radio system for both the contiguous United States (CONUS) and Canada service regions. Sirius delivers over 100 channels of talk and music to subscribers in CONUS. The service is available to different markets, such as vehicles, homes, portables, marine, and aviation, and is offered on a subscription basis. Descriptions and performance of the Sirius system are detailed herein. Copyright © 2008 John Wiley & Sons, Ltd.
Testing for the presence of multiple sources of informative dropout in longitudinal data
Authors: Crawford S. B. , Hanfelt J. J. 
Published: July 2008

AbstractLongitudinal studies tracking the rate of change are subject to patient dropout. This dropout process might not only be informative but also heterogeneous in the sense that different causes might contribute to multiple patterns of informative dropout. We propose a random‐effects approach to test for homogeneity of informative dropout that accommodates the realistic situation where reasons for dropout are not fully understood, or perhaps are even entirely unknown. The proposed score test is robust in that it does not depend on the underlying distribution of the informative dropout random effects. The test allows for an additional level of clustering among participating subjects, as might be found in a family study, provided the informative dropout random effects have a known correlation structure. Copyright © 2008 John Wiley & Sons, Ltd.
A maximum likelihood latent variable regression model for multiple informants
Authors: Horton Nicholas J. , Roberts Kevin , Ryan Louise , Suglia Shakira Franco , Wright Rosalind J. 
Published: July 2008

AbstractStudies pertaining to childhood psychopathology often incorporate information from multiple sources (or informants). For example, measurement of some factor of particular interest might be collected from parents, teachers as well as the children being studied. We propose a latent variable modeling framework to incorporate multiple informant predictor data. Several related models are presented, and likelihood ratio tests are introduced to formally compare fit. The incorporation of partially observed subjects is addressed under a variety of missing data mechanisms. The methods are motivated by and applied to a study of the association of chronic exposure to violence on asthma in children. Copyright © 2008 John Wiley & Sons, Ltd.
Estimation of risk factor associations when the response is influenced by medication use: An imputation approach
Authors: McClelland Robyn L. , Kronmal Richard A. , Haessler Jeffrey , Blumenthal Roger S. , Goff David C. 
Published: July 2008

AbstractWhen the outcome of interest is a quantity whose value may be altered through the use of medications, estimation of associations with this outcome is a challenging statistical problem. For participants taking medication the treated value is observed, but the underlying ‘untreated’ value may be the measure that is truly of interest. Problematically, those with the highest untreated values may have some of the lowest observed measurements due to the effectiveness of medications. In this paper we propose an approach in which we parametrically estimate the underlying untreated variable of interest as a function of the observed treated value, and dose and type of medication. Multiple imputation is used to incorporate the variability induced by the estimation. We show that this approach yields more realistic parameter estimates than other more traditional approaches to the problem and that study conclusions may be altered in a meaningful way by using the imputed values. Copyright © 2008 John Wiley & Sons, Ltd.
Predicting impacts of mass‐screening policy changes on breast cancer mortality
Authors: Seppänen Johanna , Heinävaara Sirpa , Hakulinen Timo 
Published: July 2008

AbstractThe aim of this study is to present a methodology for taking into account the mass‐screening invitation data in breast cancer mortality predictions, particularly in assessing impacts of screening policy changes on the short‐term predictions. The methodology is applied to a database that includes observed year‐ and age‐specific screening invitation schemes in Finnish municipalities from the time period 1987–2001. The target year for predictions is 2012.To predict mortality, breast cancer incidence and patients' survival from breast cancer are modelled with the screening data included. The knowledge of breast cancer survival together with the other cause survival is then used to calculate the number of breast cancer deaths caused by observed (1987–2001) and predicted (2002–2012) incident cases in Finland.Survival from breast cancer was estimated with a parametric mixture model where the patient population is assumed to be a combination of cured and uncured patients. This approach provides a way of modelling the hazard of fatal cases and the proportion of cured cases simultaneously. In other cause survival, the patients' hazard was allowed to differ from that of the general population.Breast cancer mortality predictions are presented according to three alternative future scenarios of screening policy. The results show no major differences between predictions yielded by alternative scenarios: Any policy change would have at the most a 3.0 per cent impact on breast cancer mortality in the near future. Copyright © 2008 John Wiley & Sons, Ltd.
Semi‐parametric maximum likelihood estimates for ROC curves of continuous‐scale tests
Authors: Zhou Xiao‐Hua , Lin Huazhen 
Published: July 2008

AbstractIn this paper, we propose a new semi‐parametric maximum likelihood (ML) estimate of a receiver operating characteristic (ROC) curve that satisfies the property of invariance of the ROC curve and is easy to compute. We show that our new estimator is$$ \sqrt {n} $$‐consistent and has an asymptotically normal distribution. Our extensive simulation studies show that the proposed method is efficient and robust. Finally, we illustrate the application of the proposed estimator in a real data set. Copyright © 2008 John Wiley & Sons, Ltd.