bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organic thin films grown by hot wall epitaxy on inorganic substrates
Authors: Sitter H. , Andreev A. , Teichert Ch. , Hlawacek G. , Haber T. , Smilgies D.‐M. , Resel R. , Ramil Alberto M. , Sariciftci N. S. 
Published: June 2005

AbstractIn this work we use Atomic Force Microscopy and X‐ray diffraction to study the morphology and thegrowth kinetics of para‐sexiphenyl layers deposited by hot wall epitaxy on crystalline mica (001) and KCl(001) substrates. It is shown that para‐sexiphenyl forms on mica very long parallel oriented crystalline needles with one preferential direction. In contrast, on KCl (001) the growth is characterized by a co‐existence of long needles (“laying” molecules) and terrace structured islands (“standing” molecules). The former belong to the initial growth stage of the films, generating a rectangular network in accordance with the surface symmetry of the substrate. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effective index model and guided modes in a photonic crystal fiber
Authors: Arriaga J. 
Published: June 2005

AbstractWe analyze the guided modes of photonic crystal fibers. We compare the values of the V‐parameter obtained using the effective index for the fundamental space‐filling mode with those values obtained by using the effective index of the modes propagating in the photonic crystal fiber. We obtain the condition for single‐mode operation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanoscopic characterization of Pr2Zr2O7 at Zr sites
Authors: Martínez J. A. , Caracoche M. C. , Rivas P. C. , Rodríguez A. M. , Bondioli F. , Manfredini T. , Ferrari A. M. 
Published: June 2005

AbstractBy using Perturbed Angular Correlation Spectroscopy, a suitable technique to explore internal fields at nanoscopic scale, the electric field gradients at Zr4+ sites in the Pr2Zr2O7 compound have been determined as a function of temperature. Three nonequivalent nanoconfigurations are present, which have been interpreted with the aid of point charge model calculations. Two of them correspond to pyrochlore – oxygen defective and perfect structures –, and the third one to the pyrochlore‐related defect fluorite structure. The most abundant interaction is a disordered and fluctuating electric field gradient, which describes the oxygen defective pyrochlore. As temperature increases, its gradual and reversible transformation towards the perfect form is observed. Below 750 °C the oxygen vacancies movement, which exhibits an activation energy of 0.14 eV, is assumed to be due to vacancies jumping among 48f equivalent sites. At higher temperatures the movement is interpreted as the fast diffusion of oxygen vacancies involving 48f and 8b sites, thus giving place to anionic disorder. The activation energy for this movement has been determined to be of 0.85 eV. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum and conversion efficiency calculation of AlGaAs/GaAs multiple quantum well solar cells
Authors: Rimada J. C. , Hernandez L. , Connolly J. P. , Barnham K. W. J. 
Published: June 2005

AbstractThe quantum well solar cell (QWSC) is a novel device that has been proposed by Barnham and co‐workers at Imperial College London. In this work, the quantum efficiency for AlGaAs/GaAs QWSC has been calculated and compared with available data from the group at Imperial College London. Quantum efficiency calculations will be presented and compared with experimental data for several AlGaAs/GaAs QWSC, obtaining good agreement. The photocurrent then is calculated from the quantum efficiency calculations and included in the J(V) relation to optimize the efficiency of AlGaAs/GaAs QWSC. It also shows that for a range of quantum well widths and barrier bandgaps the conversion efficiencies of the quantum well solar cell are higher than the corresponding homogeneous p–i–n solar cell. Our results give a broad representation of quantum well solar cell operation, and provide a profitable guide for designing and interpreting the performance characteristics of AlGaAs/GaAs QWSCs. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Confinement factor, near and far field patterns in InGaN MQW laser diodes
Authors: Martín J. , Sánchez M. 
Published: June 2005

AbstractIn this work the influence of the QW number in the active region on spectral characteristics in InGaN multi quamtun well lasers is analyzed. A comparison between the abrupt index step structure (Step) and a graded‐index structure (GRIN) is done. The effect of the introduction of a p‐AlxGa1–xN electron blocking layer, placed above the last InGaN barrier in the Step structure is also analyzed. Calculations of the confinement factor, near and far field patterns were carried out. We found that with the adequate aluminum content in this layer, the confinement factor, near and far field patterns are improved, and values similar to those obtained with GRIN structure can be reached. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cubic and hexagonal boron‐nitride (c‐BN/h‐BN) thin films deposited in situ by r.f. magnetron sputtering
Authors: Caicedo J. M. , Bejarano G. , Zambrano G. , Baca E. , Morán O. , Prieto P. 
Published: June 2005

AbstractCubic boron‐nitride (c‐BN)/hexagonal boron nitride (h‐BN) thin films were grown in situ on (100) oriented silicon substrates by r.f. (13.56 MHz) magnetron sputtering technique. In order to obtain the highest fraction of the c‐BN phase, a negative d.c bias voltage, varying from 0 to –200 V was applied to the substrate during deposition. Another set of boron nitride thin films was deposited in situ on (100) oriented silicon substrates under r.f. bias voltage. The substrate holder was biased from 0 to –350 V by connecting such to an auxiliary r.f. generator (operated at 13.56 MHz). Films were characterized by Fourier Transformed Infrared Spectroscopy (FTIR) and Atomic Force Microscope (AFM). Well‐defined peaks at 787 cm–1, 1100 cm–1 and 1387 cm–1, corresponding to the 2Au (out‐plane bending of B–N–B bond) h‐BN vibration mode, the F2 (stretching) c‐BN Transversal Optical (TO) mode and the E1u (in‐plane stretching of B–N bond) vibration mode of the h‐BN, respectively, were observed in the FTIR spectra. A maximal fraction of the c‐BN phase close to 85% was obtained under a bias voltage of –150 V at substrate temperature of 300 °C and a total pressure of 4 × 10–2 mbar. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamics of structural relaxation upon Rydberg excitation of an NO impurity in rare gas solid matrices
Authors: Rubayo‐Soneira J. , Castro‐Palacios J. C. , Rojas‐Lorenzo G. 
Published: June 2005

AbstractWe study the dynamics of structural relaxation, induced by excitation of an NO molecule, to its A2Σ+ Rydberg state in rare gas (RG) solids. Classical molecular dynamics simulations were carried out to describe the dynamics of the cage, formed by RG atoms surrounding the NO molecule. The results show a behaviour characterized by an impulsive expansion of the cage radius at short times, followed by a complex oscillatory pattern around the average NO–RG distance of ∼3.9 Å for NO(A2Σ+)–Ne, ∼4 Å for NO(A2Σ+)–Ar, ∼4.24 Å for NO(A2Σ+)–Kr, and ∼4.55 Å for NO(A2Σ+)–Xe. The size of the cage radius in the Rydberg state increases from ∼5% (Xe) to ∼25% (Ne) when compared with the initial cage radius. The experimental work showed a recurrence time of ∼1.4 ps (Ne) and ∼0.8 ps (Ar), while in our theoretical results we obtained ∼2 ps (Ne) and 0.8 ps (Ar), which is in good agreement with experimental results. The molecular dynamics simulations of the higher shells reveal a high degree of directionality of the propagation of the deformation in the solids, except in the NO–Ne solid system. We explained the dependences of the different behaviour in each system. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electric‐field gradient characterization at 181Ta impurities in sapphire single crystals
Authors: Rentería M. , Darriba G. N. , Errico L. A. , Muñoz E. L. , Eversheim P. D. 
Published: June 2005

AbstractWe report Perturbed‐Angular‐Correlation (PAC) experiments on corundum Al2O3 single crystals implanted with 181Hf/181Ta ions at the ISKP at Bonn and measured at La Plata with high efficiency and time‐resolution. The magnitude, asymmetry, and orientation (with respect to the crystalline axes) of the electric‐field gradient (EFG) tensor were determined measuring the spin‐rotation curves as a function of different orientations of the single crystals relative to the detector system. These results are analyzed in the framework of point‐charge model and ab initio Full‐Potential Linearized‐Augmented Plane Wave calculations, and compared with EFG results coming from PAC experiments with 111In/111Cd impurities. This combined study enables the determination of lattice relaxations induced by the presence of the impurity and the state of charge of a deep impurity donor level in the band gap of the semiconductor. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chemical bath deposited CdS films using magnetic treated solutions
Authors: Calzadilla O. , Hernández E. , Larramendi E. M. , Caballero‐Briones F. , Zapata‐Torres M. , Meléndez‐Lira M. , Zapata‐Navarro A. 
Published: June 2005

AbstractCdS thin films were obtained by chemical bath deposition onto corning glass slides using precursor solutions previously treated in a steady magnetic field. The kinetic growth was affected in dependence of the magnetic field intensity used in the solution treatments. The growth rate is slower when magnetized solutions are used; however, the reaction exhaustion is more delayed. The magnetic treatments improve the conversion of starting materials in thin films. Thus, the bath is more efficient and thicker films can be obtained. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Femtosecond dynamics of the transmission of gold arrays of sub‐wavelength holes
Authors: Halté V. , Benabbas A. , Guidoni L. , Bigot J.‐Y. 
Published: June 2005

AbstractWe have studied the dynamics of arrays of sub‐wavelength holes in a gold film using femtosecond pump‐probe optical spectroscopy. The real and imaginary parts of the complex non linear dielectric function ϵ of the nanostructures strongly depend on the time‐dependent redistribution of the electrons excited by the pump pulses. The dynamical behavior of ϵ allows us to explain the spectral broadening and the shift of the two resonances present in the linear transmission of the arrays. In addition, we present new experimental results allowing to compare the spectral behavior of the two transmission resonances as well as the transmission window of thick films near the interband transitions of gold. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Functional form and risk adjustment of hospital costs: Bayesian analysis of a Box–Cox random coefficients model
Authors: Hollenbeak Christopher S. 
Published: June 2005

AbstractWhile risk‐adjusted outcomes are often used to compare the performance of hospitals and physicians, the most appropriate functional form for the risk adjustment process is not always obvious for continuous outcomes such as costs. Semi‐log models are used most often to correct skewness in cost data, but there has been limited research to determine whether the log transformation is sufficient or whether another transformation is more appropriate. This study explores the most appropriate functional form for risk‐adjusting the cost of coronary artery bypass graft (CABG) surgery. Data included patients undergoing CABG surgery at four hospitals in the midwest and were fit to a Box–Cox model with random coefficients (BCRC) using Markov chain Monte Carlo methods. Marginal likelihoods and Bayes factors were computed to perform model comparison of alternative model specifications. Rankings of hospital performance were created from the simulation output and the rankings produced by Bayesian estimates were compared to rankings produced by standard models fit using classical methods. Results suggest that, for these data, the most appropriate functional form is not logarithmic, but corresponds to a Box–Cox transformation of −1. Furthermore, Bayes factors overwhelmingly rejected the natural log transformation. However, the hospital ranking induced by the BCRC model was not different from the ranking produced by maximum likelihood estimates of either the linear or semi‐log model. Copyright © 2005 John Wiley & Sons, Ltd.
Estimation of age‐specific sensitivity and sojourn time in breast cancer screening studies
Authors: Cong Xiuyu J. , Shen Yu , Miller Anthony B. 
Published: June 2005

AbstractThis study investigates statistical approaches to quantitatively describing the age effect on screening sensitivity and sojourn time distribution in breast cancer screening studies. Such an investigation is directly motivated by the need to understand the inherent relationships between age and these important quantities. We incorporate the age effect through generalized linear models under a progressive disease modelling framework and obtain the corresponding parameter estimators using the maximum likelihood method. Among a set of potential models, we use Akeike's information criterion and likelihood ratio test in model selection and inferences. Extensive simulation studies show that the estimators have reasonable accuracy and the model selection criterion works well. The proposed methods are illustrated using data from two large breast cancer screening trials. The results show that the screening sensitivity increases with age at screening examinations based on these two trials. Copyright © 2005 John Wiley & Sons, Ltd.
Multiple comparisons between two groups on multiple Bernoulli outcomes while accounting for covariates
Authors: Troendle James F. 
Published: June 2005

AbstractThe problem of adjusting for multiplicity when one has multiple outcome variables can be handled quite nicely by step‐down permutation tests. More difficult is the problem when one wants an analysis of each outcome variable to be adjusted for some covariates and the outcome variables are Bernoulli. Special permutations can be used where the outcome vectors are permuted within each strata of the data defined by the levels of the (made discrete) covariates. This method is described and shown to control the familywise error rate at any prespecified level. The method is compared through simulation to a vector bootstrap approach, also using a step‐down testing procedure. It is seen that the method using permutations within strata is superior to the vector bootstrap in terms of error control and power. The method is illustrated on a data set of 55 minor malformations of babies of diabetic and non‐diabetic mothers. Published in 2005 by John Wiley & Sons, Ltd.
The investigation and correction of recall bias for an ordinal response in a case‐control study
Authors: Barry Daniel , Livingstone Victoria 
Published: June 2005

AbstractConsider a case‐control study designed to investigate the possible association between development of a particular disease and the value of a putative risk factor measured on an ordinal scale. Let E denote a subject's true risk factor value and let E* denote a subject's recorded risk factor value. Misclassification bias occurs if conclusions reached regarding the relationship between disease status and E* do not also apply to the relationship between disease status and E. We propose a model for the conditional probability distribution of E* given E. We show how the model may be used to investigate misclassification bias in a validation study where measurements of E* and E are available for both cases and controls and apply the methods developed to data from a test–retest study of recall bias in the context of screening for hypertension. We also consider a situation where the validation study is carried out on a subset of the subjects within a larger case‐control study. In that case, values for E* are available for all subjects but values for E are available only for those subjects included in the validation study. We show how correct likelihood‐based inference concerning association between disease status and risk factor value may be carried out using all of the available data. A Monte Carlo study shows how the inclusion of a validation study leads to a correction of recall bias problems at the cost of an increased standard error for the estimated association parameter. Copyright © 2005 John Wiley & Sons, Ltd.
Model mis‐specification and overestimation of the intraclass correlation coefficient in cluster randomized trials
Authors: Giraudeau Bruno 
Published: June 2005

AbstractIntraclass correlation coefficient (ICC) estimates must be provided when reporting the results of a cluster randomized trial. This study demonstrates that estimating this parameter with one‐way ANOVA and an underlying mixed‐effects statistical model leads to biased estimates. The bias depends on the effect size of the studied treatment. Copyright © 2005 John Wiley & Sons, Ltd.
Relationship between nuchal translucency thickness and prevalence of major cardiac defects in fetuses with normal karyotype
Authors: Atzei A. , Gajewska K. , Huggon I. C. , Allan L. , Nicolaides K. H. 
Published: June 2005

AbstractObjectiveTo define the prevalence of major cardiac defects according to nuchal translucency (NT) thickness at the 11 to 13 + 6‐week scan in fetuses with normal karyotype.MethodsSpecialist fetal echocardiography was carried in 6921 fetuses with normal or presumed normal karyotype at a median gestation of 20 (range 12–35) weeks. The indications for fetal echocardiography were increased NT thickness (n = 3444), detailed second‐trimester scan either for assessment of risk of chromosomal abnormalities (n = 2980) or previous or family history of fetal defects (n = 497). The cardiac defects were grouped into six functional categories: septal defect, left inflow obstruction, right inflow obstruction, left outflow obstruction, right outflow obstruction and other.ResultsMajor cardiac defects were identified in 132 (19.1 per 1000) fetuses and the prevalence increased with fetal NT thickness from 4.9 per 1000 in those with NT below the median, to 8.7 for NT between the median and less than the 95th centile, 18.2 for NT between the 95th and 99th centiles, and exponentially thereafter to 35.2, 64.4 and 126.7 for respective NTs of 3.5–4.4 mm, 4.5–5.4 mm and ≥ 5.5 mm. There was no obvious difference in the distribution of NT in the different types of cardiac defects.ConclusionsThe prevalence of major cardiac defects increases exponentially with fetal NT thickness and in fetuses with NT of 3.5 mm or more it is higher than in pregnancies with a family history of cardiac defects. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Asymptotic expansions and analytic dynamic equations
Authors: Bohner M. , Lutz D.A. 
Published: June 2005

AbstractTime scales have been introduced in order to unify the theories of differential and difference equations and in order to extend these cases to many other so‐called dynamic equations. In this paper we consider a linear dynamic equation on a time scale together with a perturbed equation. We show that, if certain exponential dichotomy conditions are satisfied, then for any solution of the perturbed equation there exists a solution of the unperturbed equation that asymptotically differs from the solution of the perturbed equation no more than the order of the perturbation term. In order to show this perturbation theorem, we use many properties of the exponential function on time scales and derive several bounds for certain monomials that appear in the dynamic version of Taylor's formula.
Analysis of paper pressing: the saturated one‐dimensional case
Authors: Bežanović D. , van Duijn C.J. , Kaasschieter E.F. 
Published: June 2005

AbstractWe derive a one‐dimensional model that describes pressing of water saturated paper in the press‐section of the paper machine. The model involves two nonlinear diffusion equations which are coupled across an internal boundary. Existence and uniqueness as a number of qualitative properties are demonstrated. Further, computational results for a concrete case are discussed.
Relationships among negative and positive behaviours in adolescence
Authors: Boles Shawn , Biglan Anthony , Smolkowski Keith 
Published: June 2005

AbstractThe authors calculated binary indicators of seven positive and 23 negative behaviours for 22,898 8th and 15,828 11th grade students who participated in the Oregon Healthy Teens Survey across two school years. Relationships among these variables, using both the Jaccard measure of co‐occurrence and the relative risk for each member of each variable pair, given exposure to the other, showed strong inter‐relationships within, but not between, the sets of behaviours. The likelihood of negative behaviours given negative behaviours was much stronger than the likelihood of positive behaviours given positive behaviours. Positive behaviours provided little protection against the likelihood of negative behaviors.
Adhesiveness of β5 integrin variant lacking FNK767–769 is similar to that of the prototype containing FNKFNK764–769
Authors: Kawahara Ei , Saito Ayumi , Kobayashi Jun , Maenaka Shiori , Minamoto Toshinari , Imai Miwa Akasofu , Oda Yoshio 
Published: June 2005

AbstractLittle is known about the functions of two different β5 integrins: repeated‐FNK (FNKFNK764–769) and single‐FNK (FNK764–766) amino acid sequences in the cytoplasmic domain. We examined whether they occurred as germ line mutations or somatic mutations associated with neoplastic transformation, and whether there were functional alterations. Out of six cultured cell lines, only KATO‐III cells had the single‐FNK β5 sequence. The single‐FNK β5 was found in 9 out of 79 patients with colon carcinoma, but no somatic mutations were detected in cancerous tissues. CHO cells were transformed with expression vectors containing single‐FNK or repeated‐FNK β5 cDNA, which were derived from KATO‐III cells. CHO cells transfected with single‐FNK and repeated‐FNK showed similar adhesiveness to, and proliferative activity on, vitronectin substrates.
Identification and expression of the amphioxus Cks1 gene
Authors: Yang Hui , Chen Zhong‐Ke , Zhang Xiao‐Hui , Huang Xiang‐Wei , Zhang Pei‐Jun , Zhang Hong‐Wei 
Published: June 2005

AbstractA full‐length Cks1 homologue gene, AmphiCks1, was identified in amphioxus, Branchiostoma belcheri tsingtauense. Sequence characteristics, phylogeny and patterns of expression during embryonic and larval development were established. The protein predicted from AmphiCks1 showed high sequence identity with vertebrate and invertebrate homologues. Protein structural studies and phylogenetic analysis suggested that Cks homologues are evolutionarily conserved. The AmphiCks1 transcript was detected in most early developmental stages by northern blotting and whole‐mount in situ hybridization, suggesting a role for the gene in cell division.