bluuebunny/crossref_metadata_2025 huggingface dataset:
Using meta ethnography to synthesise qualitative research: a worked example
Authors: Britten Nicky , Campbell Rona , Pope Catherine , Donovan Jenny , Morgan Myfanwy , Pill Roisin
Published: November 2002

Objectives: To demonstrate the benefits of applying meta ethnography to the synthesis of qualitative research, by means of a worked example.

Methods: Four papers about lay meanings of medicines were arbitrarily chosen. Noblit and Hare's seven-step process for conducting a meta ethnography was employed: getting started; deciding what is relevant to the initial interest; reading the studies; determining how the studies are related; translating the studies into one another; synthesising translations; and expressing the synthesis.

Results: Six key concepts were identified: adherence/compliance; self-regulation; aversion; alternative coping strategies; sanctions; and selective disclosure. Four second-order interpretations (derived from the chosen papers) were identified, on the basis of which four third-order interpretations (based on the key concepts and second-order interpretations) were constructed. These were all linked together in a line of argument that accounts for patients' medicine-taking behaviour and communication with health professionals in different settings. Third-order interpretations were developed which were not only consistent with the original results but also extended beyond them.

Conclusions: It is possible to use meta ethnography to synthesise the results of qualitative research. The worked example has produced middle-range theories in the form of hypotheses that could be tested by other researchers.
Wind Speed Distributions: A New Catalogue of Defined Models
Authors: Chadee Jason. C. , Sharma Chandrabhan
Published: November 2002

Significant efforts has been dedicated to a statistical bivariate or univariate probability density function (pdf) as the model for compact representation of the enormous volume of raw wind data of a regime. This is essential for wind energy conversion system (WECS) studies or for power system planning and reliability studies. However, the literature review of this paper found that acceptance of only the industry-standard two-parameter Weibull model (WE2) is questionable. Complex wind speed phenomena demand a model that is good for both interpolation and extrapolation. The main objective of this study is to revitalise interest in wind speed frequency modelling by defining a catalogue of flexible theoretical/empirical models belonging to the Johnson, Gamma and Extreme Value families for new applicability. Definition is focussed on the three or more parameter models that are physically adaptable to wind speed. The robust Maximum Likelihood Method (MLM) and Probability Weighted Moments (PW M) method accomplish parametric estimation. The lesser efficient, but popular, Method of Moments (MOM) is also given. This paper is a glossary of such models. The substantial task of investigation and justification of particular models for wind speed and wind power analysis is not attempted here.
Crouzon syndrome: Association with absent pulmonary valve syndrome and severe tracheobronchomalacia
Authors: Beck Raphael , Sertie Andrea L. , Brik Riva , Shinawi Marwan
Published: November 2002

Airway obstruction is common among patients with craniosynostosis. We describe an infant with a clinical and genetic diagnosis of Crouzon syndrome who presented with respiratory distress and heart murmur in early neonatal life. Cardiac evaluation revealed absent pulmonary valve syndrome. She needed intubation at age 1 month, and repeated trials of extubation failed because of marked respiratory distress, stridor, and severe expiratory obstruction and wheezing. Correction of her cardiac anomaly did not relieve her respiratory distress; only after endobronchial stenting and tracheostomy was it possible to gradually wean her from mechanical ventilation. This case report demonstrates and discusses the different causes of airway obstruction in Crouzon syndrome and the morbidity and mortality that can result from pulmonary involvement in this craniosynostotic syndrome. It also demonstrates the difficult therapeutic challenge created by the combination of cardiopulmonary abnormalities in Crouzon patients. Pediatr Pulmonol. 2002; 34:478–481. © 2002 Wiley‐Liss, Inc.
Measuring ease of breathing in young patients with cystic fibrosis
Authors: Orenstein David M. , Holt Lori S. , Rebovich Paul , Campbell Thomas , Nixon Patricia
Published: November 2002

Our objective was to compare two new objective measures of ease of breathing with the visual analog scale (VAS). Twenty‐eight patients with CF, 7–34 years old (FEV1 25–114% of predicted), enrolled. Ease of breathing was evaluated by a standard 10‐cm VAS, maximum phonation (time, in seconds, to sustain the syllable “Ahh”) using a single breath, and counting in a single breath at one number per second (Count) at rest, following 3 min of stepping exercise at 15 steps per minute (STEP15), and 3 min at 30 steps per minute (STEP30). Heart rate (HR) and oxyhemoglobin saturation (SaO2) were measured.

HR and VAS increased significantly, and SaO2, phonation, and Count decreased significantly from rest to STEP15 and STEP30. Phonation time correlated significantly (and inversely) with HR after exercise. Phonation time was positively correlated with SaO2 at rest and after STEP30. Counts at rest and after STEP30 were significantly related to SaO2. VAS showed no relationship to heart rate at rest or after exercise, but was related to SaO2 at the end of STEP30. Test‐retest reliability for three trials of phonation was 0.92, and for the five trials of counting was 0.93. Correlation coefficients for maximum phonation at rest, STEP15, and STEP30 on 2 separate days were 0.61, 0.94, and 0.91, respectively. Correlation coefficients for Count at rest, STEP15, and STEP30 on 2 separate days were 0.96, 0.94, and 0.94, respectively. Correlation coefficients for VAS at rest, STEP15, and STEP30 on 2 separate days were 0.25, 0.89, and 0.97, respectively. Thus both the maximum phonation and Count have good test‐retest reliability within one session, and across 2 separate days, for both rest and exercise conditions.

In conclusion, maximum phonation and Count are valid and reliable measures of ease of breathing; they reflect increasing work loads and show stronger correlations with heart rate and SaO2 than does VAS. These measures could be an important tool for clinical research and patient care. Pediatr Pulmonol. 2002; 34:473–477. © 2002 Wiley‐Liss, Inc.
Cystic fibrosis presenting as acute pancreatitis and obstructive azoospermia in a young adult male with a novel mutation in the CFTR gene
Authors: Conway Steven P. , Peckham Daniel G. , Chu Carol E. , Ellis Lucy A. , Ahmed Mushtaq , Taylor Graham R.
Published: November 2002

Cystic fibrosis is rare in the Asian population, and is often associated with consanguinity and rare genotypes. We report on a 23‐year‐old Asian man from a consanguineous pedigree referred to the regional cystic fibrosis unit after a diagnosis of congenital bilateral absence of the vas deferens during investigations for infertility. A detailed history revealed several previous episodes of acute pancreatitis. Full diagnostic appraisal showed homozygosity for a novel cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation, but normal sweat test and nasal potential difference studies. An endoscopic retrograde cholangiopancreatogram (ERCP) showed chronic pancreatitis with bulky side branches. The vas deferens and the pancreas appeared exquisitely sensitive to mild CFTR dysfunction. Patients with cystic fibrosis and unexplained upper abdominal pain should be screened for pancreatitis, and consideration should be given to screening patients with idiopathic pancreatitis for mutations in the CFTR gene. Pediatr Pulmonol. 2002; 34:491–495. © 2002 Wiley‐Liss, Inc.
Relapsed non‐Hodgkin's lymphoma diagnosed by flexible bronchoscopy
Authors: Phadke Shruti M. , Chini Barbara A. , Patton Donna , Goyal Rakesh K.
Published: November 2002

Pulmonary relapse of non‐Hodgkin's lymphoma (NHL) occurred in a 10‐year‐old girl who presented with cough, blood‐tinged sputum, and chest tightness. The diagnosis of Ki‐1 (CD30) anaplastic large‐cell lymphoma was established using bronchoalveolar lavage (BAL) and transbronchial biopsy (TBB). These procedures demonstrated malignant cells that stained positive for CD30 and had the t(2;5) translocation, thereby avoiding the need for an open lung biopsy. Pediatr Pulmonol. 2002; 34:488–490. © 2002 Wiley‐Liss, Inc.
Opioid peptide receptor studies. 16. Chronic morphine alters G‐protein function in cells expressing the cloned mu opioid receptor
Authors: Xu Heng , Lu Yi‐Feng , Rothman Richard B.
Published: November 2002

Chronic morphine treatment results in functional uncoupling of the mu opioid receptor and its G protein in both cell culture and animal models. In the present study, Chinese hamster ovary (CHO) cells stably expressing the cloned human mu opioid receptor (hMOR‐CHO cells) were incubated with 1 μM of morphine (or no drug) for 20 h. Subsequently, we assessed DAMGO‐ and morphine‐stimulated [35S]‐GTP‐γ‐S binding and agonist‐mediated inhibition of forskolin‐stimulated cAMP accumulation. Using a single concentration of [35S]‐GTP‐γ‐S (0.05 nM), chronic morphine treatment did not significantly change basal [35S]‐GTP‐γ‐S binding, shifted the morphine EC50 from 59 nM to 146 nM, and decreased the maximal stimulation (Emax) from 201% to 177%. Similar results were observed with DAMGO. Binding surface analysis resolved two [35S]‐GTP‐γ‐S binding sites (high‐affinity and low‐affinity sites). In control cells, morphine stimulated [35S]‐GTP‐γ‐S binding by increasing the Bmax of the high‐affinity site. In morphine‐treated cells, morphine stimulated [35S]‐GTP‐γ‐S binding by decreasing the high‐affinity Kd without changing the Bmax. Morphine treatment increased the EC50 (5–11‐fold) for agonist‐mediated inhibition of forskolin‐stimulated cAMP accumulation. These changes were not observed in cells expressing a mutant mu opioid receptor which does not develop morphine tolerance, suggesting that the changes in [35S]‐GTP‐γ‐S binding observed in hMOR‐CHO cells result from the development of morphine tolerance. Synapse 47:1–9, 2003. Published 2002 Wiley‐Liss, Inc.
Hole mobility in AlxGa1−xSb grown by metalorganic chemical vapor deposition
Authors: Ramelan A. H. , Goldys E. M.
Published: November 2002

The temperature dependence of the hole mobilities of AlxGa1−xSb films in the regime 0⩽x⩽0.25 has been examined by Van der Pauw–Hall measurements. The films have been grown by metalorganic chemical vapor deposition on Si–GaAs substrates using TMAl, TMGa, and TMSb precursors. The mobility decreases sharply when a small amount of Al in the range 0<x<0.025 is incorporated into GaSb. The temperature dependence of mobility was analyzed using a model with contributions from various scattering mechanisms. At a low-temperature (<100 K), the mobility decreased due to a contribution from ionized-impurity scattering and in a high-temperature region (>100 K), the same effect was due to lattice phonon scattering. At 300 and 77 K, the alloy scattering is the most important mechanism in AlxGa1−xSb ternaries, however the temperature dependence of alloy scattering is less pronounced as the temperature decreases.
Plasma mechanism of terahertz photomixing in high-electron mobility transistor under interband photoexcitation
Authors: Ryzhii V. , Khmyrova I. , Satou A. , Vaccaro P. O. , Aida T. , Shur M.
Published: November 2002

We show that modulated near-infrared radiation can generate terahertz plasma oscillations in the channel of a high-electron mobility transistor. This effect is associated with a temporarily periodic injection of the electrons photoexcited by modulated near-infrared radiation into the transistor channel. The excitation of the plasma oscillations has the resonant character. It results in the pertinent excitation of the electric current in the external circuit that can be used for generation of terahertz electromagnetic radiation.
Magnetoinductive waves in one, two, and three dimensions
Authors: Shamonina E. , Kalinin V. A. , Ringhofer K. H. , Solymar L.
Published: November 2002

The propagation of waves supported by capacitively loaded loops is investigated using a circuit model in which each loop is coupled magnetically to a number of other loops. Since the coupling is due to induced voltages the waves are referred to as magnetoinductive (MI) waves. The mathematical formulations are mostly analytical thanks to long standing previous work on the magnetic and electric fields generated by currents flowing in loops. Retardation is neglected, i.e., dimensions of the structure are assumed to be small relative to the free space wavelength. The dispersion relations, derived in the most general case for a tetragonal three-dimensional structure, exhibit both forward and backward waves within a pass band. It is shown that for reproducing the salient features of the waves it is sufficient to take nearest neighbor coupling into account but coupling between loops further away must also be considered if higher accuracy is required. The investigations include that of resonances, conditions for the existence of traveling waves, tolerances, and streamlines of the Poynting vector. Waveguide components, like bends, power dividers and couplers are considered due to the potential applications of the MI waves as magnetic guides. Generality of the results, their possible implications for transverse electromagnetic wave propagation, previous work on similar waves, including the possibility of phase conjugation, are discussed in a separate section.
Ab initio pseudopotential study of a model tetracene/ZnSe organic–inorganic superlattice: Its electronic structure and optical responses
Authors: Hamada Tomoyuki
Published: November 2002

The electronic structure and complex dielectric function of a model organic–inorganic superlattice (OISL) composed of organic tetracene and inorganic ZnSe were investigated at the atomic level by using a nonlocal density functional pseudopotential method and random phase approximation. It was found that the OISL has a two-dimensional electronic structure, similar to that of inorganic superlattices, and is a type II-misaligned superlattice confining electrons and holes in the ZnSe and tetracene layers, respectively. The misaligned magnitude of the OISL was estimated to be about 1.6 eV. Theoretical calculations clarified that the OISL is not a simple multilayered composite material composed of tetracene and ZnSe, but it is a material showing significant superlattice effects, in terms of its electronic structure and optical responses, owing to two-dimensionally delocalized electrons present in the ZnSe layers.
Heat treatment effects on electrical and optical properties of ternary compound In2O3–ZnO films
Authors: Lee Jung-Kyung , Kim Hwa-Min , Park Seoung-Hwan , Kim Jong-Jae , Rhee Byung-Roh , Sohn Sang-Ho
Published: November 2002

Heat treatment effects on the electrical and optical properties are investigated for In2O3–ZnO film with a Zn content [Zn/(In+Zn)] of 33 at. %. Thin films deposited in a mixed gas atmosphere (Ar+20% O2) by a magnetron sputtering method show high resistivity of about 1.7×10−1 Ω cm. A mixture of In2O3 (99.999%) and ZnO (99.999%) powders calcined at 1000 °C in an Ar atmosphere for 2 h was used as the target. On the other hand, the films deposited in a pure Ar gas environment show low resistivity of about 3×10−4 Ω cm, comparable to that of indium tin oxide films (10−4 Ω cm). After heat treatment at 650 °C in vacuum, it was found that the films deposited in a mixed gas atmosphere revealed low resistivity similar to that of films deposited in a pure Ar gas. For these annealed films, their electrical properties are very stable when treated at temperatures up to 500 °C in air or 650 °C in vacuum. Also, it is found that the optical band gap of In2O3–ZnO films increase (or decrease) after the heat treatment in vacuum (or O2 atmosphere). These effects are mainly due to the change in carrier concentration before and after heat treatment.
Analysis of pattern formation and phase separation in the immunological synapse
Authors: Hori Yuko , Raychaudhuri Subhadip , Chakraborty Arup K.
Published: November 2002

T lymphocytes (T cells) play an important role in orchestrating an adaptive immune response in complex organisms. Recent experiments have shown that when T cells recognize antigen presenting cells, a complex and large-scale reorganization of intercellular membrane proteins and cell shape occurs. The resulting motif is implicated in information transfer between T cells and antigen presenting cells, and has been labeled the immunological synapse. Numerical solutions of a mathematical model that incorporates binding kinetics, protein mobility, and down regulation, and membrane mechanics has proven successful in describing some of these observations. In this paper, we analyze the equations that describe this model, and this sheds light on the origins of pattern formation in the immunological synapse. In particular, the thermodynamic considerations and dynamic instabilities that lead to pattern formation in and out of equilibrium are elucidated.
On the inelastic shock profile in alumina
Authors: Marom H. , Sherman D. , Rosenberg Z. , Murray N.
Published: November 2002

The dynamic response of alumina specimens, above their elastic limits, was studied using planar impact experiments with different tile thickness. Stress-time measurements with manganin gauges show a steady spreading of the inelastic portion of the shock profile with increasing tile thickness. Such behavior is typical of elastic waves moving at a constant speed that depends on their amplitude. This finding supports recent interpretations of the failure ramp, by which the elastic response of these materials should be extended to higher stresses than the initial jump. However, further analysis of these profiles raises some questions regarding the exact determination of the Hugoniot elastic limit.
Mass transfer mechanism in real crystals by pulsed laser irradiation
Authors: Pogorelov A. E. , Ryaboshapka K. P. , Zhuravlyov A. F.
Published: November 2002

Dynamic processes in near-surface layers of metals subjected to the influence of a pulsed laser irradiation, which does not destroy the crystalline structure, are considered in detail. The method of calculation of the density of dislocations generated in the metal volume during relaxation processes and at repeated pulse laser action is presented. Results of evaluations coincide to high precision with the transmission electron microscopy data. On the basis of ideas of structural defects interaction in dynamically deformated condensed matter the dislocation-interstitial mechanism of laser-stimulated mass transfer in real crystals is proposed. The good compliance of theoretical and experimental results approves a defining role of the presented mechanism of mass transfer at pulse laser action on metals. The possible implementation of this dislocation-interstitial mechanism of mass transfer in metals to other cases of pulse influences is justified.
Fission-fragment spikes in uranium dioxide
Authors: Ronchi C. , Wiss T.
Published: November 2002

The article deals with some fundamental aspects of the fission energy dispersion in nuclear reactor fuel. The analysis starts from the transmission electron microscope observation of tracks produced by energetic fission fragments in thin foils of UO2 single crystals. On the one hand, these tracks appear on the free surface as explosive material displacements. On the other, the passage of fission fragments in the bulk does not leave visible, continuous traces. Furthermore, irradiated U4O9, which consists of a UO2 lattice hosting a temperature sensitive superstructure of interstitial oxygen, persists after experiencing the near-field action of fission fragment thermal spikes. These seemingly inconsistent phenomena have been explained by showing that a large fraction of the fission fragment electronic losses is converted in strong shock waves whose passage in the solid is too fast for producing atomic displacements, but which can release high energies by unloading on free surfaces. The consequent matter displacements have been shown to have important effects on the structural properties of the nuclear fuel.
Reaction of diamond thin films with atomic oxygen simulated as low-earth-orbit environment
Authors: Li Jingqi , Zhang Qing , Yoon S. F. , Ahn J. , Zhou Qiang , Wang Sigen , Yang Dajiang , Wang Qiang , Li Zhonghua , Wang Jingyi , Lei Qingsong
Published: November 2002

Diamond thin films deposited using a hot filament chemical vapor deposition (CVD) technique have been explored to atomic oxygen simulated as low-earth-orbit environment to examine their erosion-resistance properties. X-ray photoelectron spectroscopy results suggest that the atomic oxygen reacts with the diamond surface and forms ether (C–O–C) and carbonyl (>C=O) configurations. After a 3 h exposure to the atomic oxygen beam with a flux of 2.6×1016 atoms/cm2s, the diamond films only show a small mass loss with a reaction efficiency of 8.28×10−26 cm3/atom. Such a small reaction efficiency suggests that the CVD diamond is highly erosion resistive to atomic oxygen and it can be used as a passivation material in space.
Intrinsic grain size and distribution due to boron addition in CoCrPt alloys
Authors: Ajan Antony , Okamoto I.
Published: November 2002

Intrinsic grain size, its distribution and magnetic properties due to the addition of B on CoCrPtB recording magnetic layer are studied for various B compositions (0–10 at. %). CoCrPtB films were grown on large CrMo grains with an average grain size of ∼27 nm in order to obtain the intrinsic grain structure of the B containing magnetic layer, maintaining good Co (1120) crystallographic texture. Remarkable reduction in average intrinsic grain diameter is observed from ∼24 to ∼6.9 nm as the B concentration was varied from 0 to 10 at. %, respectively, on CoCrPt. The presence of B both within and outside the ferromagnetic phase is suggested to explain the observed coercivity dependence in CoCrPtB systems.
Relative significance of particle anisotropy in systems of ultrafine ferromagnetic particles
Authors: Porto Markus
Published: November 2002

The relative weight of particle anisotropy in systems of dipolarly interacting single-domain ultrafine ferromagnetic particles is investigated based on the comparison between a simple model and a particular variant of it. The latter differs from the former by the absence of particle anisotropy, and both are investigated in parallel by Monte Carlo simulations of zero field cooling and field cooling experiments. By comparing systems characterized by different particle concentrations as well as by various types of particle positions’ disorder, it is shown that the relative importance of the particle anisotropy, besides the expected dependence on the particle concentration, crucially depends on the positional disorder.
Electrical network-based time-dependent model of electrical breakdown in water
Authors: Joshi R. P. , Qian J. , Schoenbach K. H.
Published: November 2002

A time-dependent, two-dimensional, percolative approach to model dielectric breakdown based on a network of parallel resistor–capacitor elements having random values, has been developed. The breakdown criteria rely on a threshold electric field and on energy dissipation exceeding the heat of vaporization. By carrying out this time-dependent analysis, the development and propagation of streamers and prebreakdown dynamical evolution have been obtained directly. These model simulations also provide the streamer shape, characteristics such as streamer velocity, the prebreakdown delay time, time-dependent current, and relationship between breakdown times, and applied electric fields for a given geometry. The results agree well with experimental data and reports in literature. The time to breakdown (tbr) for a 100 μm water gap has been shown to be strong function of the applied bias, with a 15–185 ns range. It is also shown that the current is fashioned not only by dynamic changes in local resistance, but that capacitive modifications arising from vaporization and streamer development also affect the transient behavior.
Nuclear cusp of the virial exchange energy density for spherical atoms
Authors: Sen K. D. , Geerlings Paul
Published: November 2002

Using the virial exchange energy density defined by the integrand of the Levy–Perdew exchange virial relation, εxvirial[ρ](r)=[3ρ(r)+r⋅∇ρ(r)][δEx[ρ]/δρ(r)], it is shown that for spherical atoms with nuclear charge Z, the nuclear cusp of exchange energy density [(1/εxvirial)(δεxvirial/δr)]r→0=−(8Z/3). For the local density approximation, this condition is given by −10Z/3. Numerical results are presented for the rare gas atoms He–Xe using a variety of exchange-only local effective potentials. For the optimized effective potential and local density approximation the above conditions are obeyed quantitatively. It is found that the Krieger–Li–Iafrate approximation closely reproduces the optimized effective potential results, whereas those derived from the popular potentials due to Becke and Perdew–Wang give rise to much larger values. The exchange energy density defined analogously as the integrand of the directly calculated exchange energy of the model potential leads to the exact cusp values of −2Z for the optimized effective potential and −8Z/3 for the local density approximation.
Theoretical investigation of the effect of the rare gas matrices on the vibrational spectra of solvated molecular ions: Cu+CO
Authors: Bludský O. , Šilhan M. , Nachtigall P.
Published: November 2002

The effect of the rare-gas matrices on the vibrational spectra of solvated molecular ions was investigated. An approach based on the full-dimensional coupled-clusters description of the gas phase ion augmented with the Monte Carlo averaging of frequency shift due to the interaction with the matrix is presented. The calculated νR(CO) of the Cu+CO ion in the Ne matrix at 2229 cm−1 agrees within 5 cm−1 with the experimentally determined value. The remaining small discrepancy between theory and experiment is due to the error in harmonic frequency calculations of the gas phase Cu+CO ion at the coupled-clusters level of theory. Calculated frequency shift due to the effect of Ne matrix allows us to predict the gas-phase harmonic ω=2272 cm−1 and anharmonic ν=2243 cm−1 vibrational frequencies for Cu+CO. A large difference (−31 cm−1) in ΔνR(CO) stretching frequencies between Ne and Ar matrices was found. The ΔνR(CO) does not depend on the cavity size and on the temperature. Major contribution to ΔνR(CO) comes from five Ar atoms. Together with the CO ligand these five atoms are octahedrally coordinated to the Cu+ ion. The effect of the basis set superposition error was found to be important for the calculations of ΔνR(CO) in the rare-gas matrix.
Molecular dynamics simulations of structural transitions and phase coexistence in water pentamers
Authors: Bosma Wayne B. , Rhodes Maria M.
Published: November 2002

Molecular dynamics simulations of water pentamers were carried out using the semiempirical Parameterization Method 3 method to calculate the forces. Simulations were performed in the microcanonical ensemble, at several (average) vibrational temperatures. Three distinct transitions were observed in these systems, corresponding to the onset of phase coexistence and of two hydrogen bond rearrangements that were predicted by previous structural calculations. A detailed study of the high-temperature pentamer dynamics is presented, which clarifies the distinction between liquidlike behavior and simple structural rearrangements in these systems.
Dissociative photoionization of N2O in the region of the N2O+(C 2Σ+) state, studied by ion–electron velocity vector correlation
Authors: Lebech M. , Houver J. C. , Dowek D. , Lucchese R. R.
Published: November 2002

Imaging and time-of-flight-resolved coincidence techniques are combined to extend the (VA+,Ve,P) vector correlation method to the study of dissociative photoionization of small polyatomic molecules breaking into two heavy fragments. Dissociative photoionization (DPI) of the N2O linear molecule into the N2O+(C 2Σ+) ionic state, induced by linearly polarized synchrotron radiation (P), is chosen as an example. The ion–electron kinetic energy correlation enables the identification of all the DPI processes producing the NO+, N+, N2+, and O+ fragments. The IχA+(θe,φe) molecular frame photoelectron angular distributions (MFPADs), deduced from the spatial analysis of the (VNO+/N+,Ve,P) vector correlations, exhibit remarkable features. When the N2O molecule is aligned parallel to the polarization axis, a preferred electron emission from the N2O+ molecular ion in the direction perpendicular to the molecular axis, as well as a strong forward–backward asymmetry that favors electron emission along the molecular axis in the same direction as the N+ or N fragment, are demonstrated. The measured MFPADs are found in good agreement with the reported multichannel Schwinger configuration interaction calculations, when molecular rotation prior to dissociation is taken into account. This comparison provides an estimation of the lifetime of the N2O+(C 2Σ+) state prior to dissociation into the dominant channels [NO+(X 1Σ+)+N(2P)] and [N+(3P)+NO(X 2Π)], which is found to be about 2 ps.
Cross correlation functions Cnm(E) via Lanczos algorithms without diagonalization
Authors: Karlsson Hans O. , Holmgren Sverker
Published: November 2002

It is shown how the quasiminimal residual algorithm (QMR), based on the Lanczos algorithm, can be modified to compute cross-correlation functions Cnm(E)=〈Ψn|(E−H)−1|Ψm〉 without any diagonalization by recursively updating a small number of scalars. Only three Lanczos vectors need to be stored. Several left-hand side vectors 〈Ψn| and multiple shifts E can be considered simultaneously. The new method is termed the quasiminimal recursive residue generation method (QM-RRGM) and is applied to the collinear H+H2 problem to illustrate its convergence behavior. The properties of two different formulations of the Lanczos algorithm, the usual three-term and a coupled two-term recursion, are also discussed. The QM-RRGM exhibits smooth convergence behavior, and it is shown that the stopping criteria used in the QMR algorithm can also be used for computing correlation functions.
Measurement of spectral lines produced by four-wave mixing in 30 km dispersion-shifted single-mode optical fiber
Authors: Jahanpanah J.
Published: November 2002

Interaction between two copropagating narrowband light waves in a monomode optical fiber can occur because of four-wave mixing phenomena. Light beams from two lasers, a tunable external cavity laser and a distributed feedback semiconductor laser with wavelength separation around 0.36 nm (45 GHz) at λ=1.545 μm, are first amplified by an erbium-doped amplifier and then launched into a 30 km dispersion-shifted fiber. The fiber acts as a nonlinear medium to mix two optical waves and generates one, two, three, and even four optical waves (sidebands) at other wavelengths. An optical spectrum analyzer with a resolution of 0.1 nm has been used to measure the power of the output sidebands. In good agreement with theory, by raising the power of input signals, the number of output sidebands and their powers is also increased.
Proportionality of vacancy concentration to ion implantation fluence
Authors: Simpson P. J. , Szpala S.
Published: November 2002

We have used positron annihilation spectroscopy to address the proportionality of vacancy production versus ion fluence in silicon. For implants of Au (energy 11.5 MeV, fluences 2×109–3×1011/cm2) and of Ge (energy 8.6 MeV, fluences 5×109–4×1011/cm2), we find that the vacancy accumulation is approximately linear (i. e., doubling the fluence doubles the vacancy concentration). This is in contrast to a variety of prior reports, both theoretical and experimental, and we show that this discrepancy is primarily a function of the range of fluences examined. We show also that sublinear vacancy accumulation at higher ion fluences is driven principally by direct overlap of damage cascades, not by defect diffusion.
Rayleigh–Taylor instability of reaction-diffusion acidity fronts
Authors: Yang J. , D’Onofrio A. , Kalliadasis S. , De Wit A.
Published: November 2002

We consider the buoyancy driven Rayleigh–Taylor instability of reaction-diffusion acidity fronts in a vertical Hele–Shaw cell using the chlorite–tetrathionate (CT) reaction as a model system. The acid autocatalysis of the CT reaction coupled to molecular diffusion yields isothermal planar reaction-diffusion fronts separating the two miscible reactants and products solutions. The reaction is triggered at the top of the Hele–Shaw cell and the resulting front propagates downwards, invading the fresh reactants, leaving the product of the reaction behind it. The density of the product solution is higher than that of the reactant solution, and hence a hydrodynamic instability develops due to unfavorable density stratification. We examine the linear stability of the isothermal traveling wavefront with respect to disturbances in the spanwise direction and demonstrate the existence of a preferred wavelength for the developed fingering instability. Our linear stability analysis is in excellent agreement with two-dimensional numerical simulations of the fully nonlinear system.
Investigation of cluster size and cluster incident energy effect on film surface roughness for ionized cluster beam deposition
Authors: Hwang Chi-Chuan , Chang Jee-Gong , Huang Gwo-Jiunn , Huang Sheng-Huang
Published: November 2002

Molecular dynamic simulation is used to investigate the influence of cluster size and cluster incident energy upon a Cu–Co magnetic film produced using the ionized cluster beam deposition process. The Co–Co, Cu–Cu, and Cu–Co atomic interactions are modeled using the many-body, tight-binding potential method, and the interface width is used to characterize the surface roughness properties at both transient and final state conditions. The results of this study indicate that the surface roughness of the deposited magnetic film is lower when a smaller incident cluster size is used. This observation is valid for all stages of the deposition process. Furthermore, it is determined that the nature of the relationship between cluster size and the produced film surface property is influenced by the cluster incident energy parameter. When the cluster incident energy is lower than an optimal value, it is observed that the produced film surface property is strongly dependent on the cluster size. However, when the value of the cluster incident energy falls between this optimal value and a critical cluster incident energy value, the correlation between cluster size and surface roughness is not so pronounced. Finally, when the cluster incident energy is higher than the critical value, it is noted that there is no significant relationship between cluster size and the resulting film surface property.
Theory of the copper vacancy in cuprous oxide
Authors: Wright A. F. , Nelson J. S.
Published: November 2002

Density-functional theory is used to examine aspects of the copper vacancy (VCu) in cuprous oxide (Cu2O). The normal vacancy configuration, obtained by simple removal of a Cu atom from the lattice, is found to be 0.1 eV higher in energy than a split vacancy configuration wherein a nearby Cu atom is displaced toward a normal vacancy site by half the bulk Cu–Cu separation. Jumps between the normal and split vacancy configurations are predicted to be rate limiting for VCu diffusion with an energy barrier of 0.3 eV. Binding of VCu to substitutional aluminum (AlCu) and indium (InCu) is examined. The neutral (AlCu+2VCu) complex is found to have a binding energy of 3.3 eV whereas the neutral (InCu+2VCu) complex is bound by 1.7 eV. The magnitudes of these binding energies suggest that AlCu and InCu should inhibit VCu diffusion in Cu2O.
Density functional model of surfactant mesostructures
Authors: Christopher P. S. , Oxtoby David W.
Published: November 2002

We present a theoretical study of the effects of amphiphile microscopic properties on mesoscopic properties of their solutions. These results were obtained using an off lattice density functional method. We consider fused hard-sphere amphiphiles with a single hard sphere solvent. Mean field attractions are accounted for with a 1/R6 dispersion interaction. Mesoscopic properties, such as the bending rigidity, saddle splay modulus, and surface tension, are presented as a function of the amphiphile hard sphere radii and attractive interaction strength. Detailed analysis of the work of amphiphile cluster formation with cluster size is presented.
The analog of Koopmans’ theorem in spin-density functional theory
Authors: Gritsenko O. V. , Baerends E. J.
Published: November 2002

For spin-unrestricted Kohn–Sham (KS) calculations on systems with an open shell ground state with total spin quantum number S, we offer the analog of the Koopmans’-type relation between orbital energies and ionization energies familiar from the Hartree–Fock model. When (case I) the lowest ion state has spin S−1/2 (typically when the neutral molecule has a (less than) half filled open shell), the orbital energy of the highest occupied orbital (φH), belonging to the open shell with majority spin (α) electrons, is equal to the ionization energy to this lowest ion state with spin S−1/2: εHα=−IS−1/2(φH−1). For lower (doubly occupied) orbitals the ionization φH−1 leaves an unpaired electron that can couple to the open shell to S±1/2 states: εiβ≈−IS+1/2(φi−1) (exact identity for i=H−1), εiα≈−{[2S/(2S+1)]IS−1/2(φi−1)+[1/(2S+1)]IS+1/2(φi−1)}, reducing to a simple average in the case of a doublet ground state (single electron outside closed shells). When the lowest ion state has spin S+1/2 (case II; typically for more than half filled open shells): εHα=εHβ=−IS+1/2(φH−1); for i<H, εiβ≈−IS+1/2(φi−1), εiα≈−{[2S/(2S+1)]IS−1/2(φi−1)+[1/(2S+1)]IS+1/2(φi−1)}. A physical basis is thus provided for the KS orbital energies also in the spin unrestricted case and an explanation is given for the common observation in approximate Kohn–Sham calculations of more negative majority spin (α) levels εiα for i<H, than minority spin levels εiβ.
Magnetic flux bifurcation and frequency doubling in rotated superconductors
Authors: Badı́a A. , López C.
Published: November 2002

Starting from our variational statement of the general critical state in type II superconductors, we develop anisotropic current flow simulations in various conditions. The theory is applied to the slab geometry under rotating applied field, parallel to the surface of the sample. By comparison to the isotropic case, we show that anisotropy strongly influences the underlying physical phenomena. A magnetic-flux bifurcation point arises for the isotropic hypothesis. The issue of this point defines a boundary between two groups of vortex lines, one of which rigidly settles within the sample and another one, which frictionally rotates relative to the sample. A much more complex scenario arises in the anisotropic case, for which dynamic fronts must be defined. As a consequence, we predict the appearance of nonlinear phenomena such as the magnetization frequency doubling. The anharmonic contribution may be tuned by the applied field modulus.
Au
9
+
:
Rapid isomerization reactions at 140 K
Authors: Weis Patrick , Bierweiler Thomas , Vollmer Elena , Kappes Manfred M.
Published: November 2002

We present ion mobility measurements for small gold cluster cations, Aun+(n⩽10) in the temperature range between 77 and 300 K. While at room temperature all cluster sizes show only one sharp peak in the arrival time distribution, the Au9+ signal becomes bimodal at temperatures below 140 K. We interpret this unusual behavior in terms of two different isomeric forms of this ion which undergo temperature dependent interconversion reactions. From the reaction rate the activation barrier for this isomerization can be estimated to be 10–20 kJ/mol.
H
2
O
vapor-induced leakage degradation of Pb(Zr,Ti)O3 thin-film capacitors with Pt and IrO2 electrodes
Authors: Baniecki J. D. , Cross J. S. , Tsukada M. , Watanabe J.
Published: November 2002

We have investigated the influence of H2O vapor on the leakage characteristics of Pb(Zr,Ti)O3 (PZT) thin-film capacitors with Pt and IrO2 top electrodes by conducting electrical measurements ex situ in air and in situ in an 80% N2/20% O2 atmosphere with controlled humidity ranging from <0.1% to 95.5% relative humidity at 20 °C. The results show that the leakage characteristics of PZT thin-film capacitors are strongly sensitive to H2O vapor in the atmosphere. The onset to H2O-induced leakage degradation depended on the relative humidity and on the quantity of charge passed through the capacitor. A degradation mechanism based on the electrolysis of H2O that has adsorbed on the capacitor from the atmosphere and the role of the electrode material in the degradation process are discussed.
Internal friction and Jahn–Teller effect in the charge-ordered La1−xCaxMnO3 (0.5⩽x⩽0.87)
Authors: Zheng R. K. , Huang R. X. , Tang A. N. , Li G. , Li X. G. , Wei J. N. , Shui J. P. , Yao Z.
Published: November 2002

The Jahn–Teller effect in the charge-ordered (CO) state for La1−xCaxMnO3 (0.5⩽x⩽0.87) was studied by measuring the low-temperature powder x-ray diffraction, internal friction, and shear modulus. We find that the electron–lattice interaction with the static Jahn–Teller distortion is the strongest near x≈0.75 in the CO state. It was particularly observed that a crossover of the Jahn–Teller vibration mode from Q2 to Q3 near x=0.75 induces crossovers of the crystal structure from tetragonally compressed to tetragonally elongated orthorhombic, and of the magnetic structure from CE-type to C-type near x=0.75. The experimental results give strong evidence that the Jahn–Teller effect not only plays a key role in stabilizing the CO state, but also determines the magnetic and crystal structures in the CO state for La1−xCaxMnO3.
Energy level alignment at zinc blende Cd(Mn)Se/ZnTe/InAs(100) interfaces
Authors: Gleim Th. , Weinhardt L. , Schmidt Th. , Fink R. , Heske C. , Umbach E. , Grabs P. , Schmidt G. , Molenkamp L. W. , Richter B. , Fleszar A. , Steinrück H.-P.
Published: November 2002

We have investigated the electronic interfacial structure of the heterovalent Cd(Mn)Se/ZnTe/InAs(100) system, which is a promising material for use in spintronic devices. By combining k-resolved valence- and core-level photoelectron spectroscopy at selected photon energies and a comparison to theoretical density of states with conduction band measurements using inverse photoemission, we find that the ZnTe interlayer leads to a stepwise alignment of the valence band offsets. The overall offset between CdSe and InAs is determined to be −0.86±0.15 eV. Furthermore, the ZnTe interlayer leads to a 1.1 eV potential barrier in the conduction band. Finally, the introduction of 12% Mn into the CdSe overlayer does not induce a significant change in the valence band discontinuity.
Development of channel waveguide lasers in Nd3+-doped chalcogenide (Ga:La:S) glass through photoinduced material modification
Authors: Mairaj Arshad K. , Riziotis Christos , Chardon Alain M. , Smith Peter G. R. , Shepherd David P. , Hewak Daniel W.
Published: November 2002

We report the development of a waveguide laser source in a neodymium-doped chalcogenide (Ga:La:S) glass. Channel waveguide structures were directly written via above band gap (λ=244 nm) illumination provided by a focused UV-laser beam with fluencies 1.5–150 J/cm2. Effects of photoinduced material modification in the form of surface compaction and photodensification were evident. Characterization revealed a low threshold waveguide laser with emission at 1075 nm and slope efficiency of 17%. The active device was spatially single mode and exhibited laser operation with 8.6 mW peak power and attenuation <0.5 dB cm−1.
Electro-optic modulation at 1.5 GHz using single-crystal film of an organic molecular salt
Authors: Thakur M. , Mishra A. , Titus J. , Ahyi A. C.
Published: November 2002

Electro-optic modulation using single-crystal film of an organic molecular salt with light propagating perpendicular to the film (transverse configuration) has been recently reported. In this letter, we report results of measurements at high speed (up to 1.5 GHz) using such films in the same configuration. Excellent signal-to-noise ratio has been observed even at a low applied voltage (1 V across 15 μm gap) for a 3 μm thick film. The magnitudes of the electro-optic coefficients are: r11=445 pm/V and r21=148 pm/V at 750 nm. A wide range of applications of these films are predicted.
Optical spectroscopy of bulk GaN crystals grown from a Na–Ga melt
Authors: Skromme B. J. , Palle K. C. , Poweleit C. D. , Yamane H. , Aoki M. , DiSalvo F. J.
Published: November 2002

Colorless transparent platelet and prismatic GaN crystals up to 3–4 mm, grown from a Na–Ga melt (0.6–0.7 mol fraction of Na) at temperatures of 700–800 °C in a modest (5 MPa) pressure of N2, are characterized using Raman scattering, room and low temperature photoluminescence, and reflectance. They exhibit sharp free and bound exciton luminescence features (down to 0.22 meV full width at half maximum), including multiple excited states. Residual Mg and Zn acceptors and a 33.6 meV donor (possibly ON) are identified. Raman spectra suggest free carrier concentrations down to the low to mid 1016 cm−3 range.
Enhancement of photoinduced anisotropy and all-optical switching in Bacteriorhodopsin films
Authors: Wu Pengfei , Rao D. V. G. L. N. , Kimball B. R. , Nakashima M. , DeCristofano B. S.
Published: November 2002

Large enhancement of photoanisotropic effects is demonstrated in thin films of the biomaterial Bacteriorhodopsin by using two exciting beams of orthogonal polarization. The mechanism of the enhancement originates from optimization of direction-selected photoisomerization of the biomaterial controlled by the polarized exciting beams. The technique is applied for achieving an all-optical switch with the additional feature of output sign control.
Measures induced by analytic functions and a problem of Walter Rudin
Authors: Sundberg Carl
Published: November 2002

The measure

μ
φ

\mu _\varphi

induced by a bounded analytic function

φ
\varphi

on the unit disk

U
U

may be defined by

μ
φ

(
E
)
=
m
(

φ

−
1

(
E
)
)

\mu _\varphi (E)=m(\varphi ^{-1}(E))

, where

m
m

is normalized Lebesgue measure on

∂
U

\partial U

. We discuss the problem of characterizing such measures, and produce some necessary conditions which we conjecture are sufficient. Our main results are a construction showing that our conjectured sufficient conditions are sufficient for a measure to be weakly approximable by induced measures, and a construction of a function

φ
\varphi

, not a constant multiple of an inner function, whose induced measure is rotationally symmetric. This function is not inner, but satisfies
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="integral phi left-parenthesis e Superscript i theta Baseline right-parenthesis Superscript m Baseline ModifyingAbove phi left-parenthesis e Superscript i theta Baseline right-parenthesis Superscript n Baseline With bar StartFraction d theta Over 2 pi EndFraction equals 0">

∫
φ

(

e

i
θ

)

m

φ

(

e

i
θ

)

n

¯

d
θ

2
π

=
0

\int \varphi \left (e^{i\theta }\right )^m\overline {\varphi \left (e^{i\theta }\right )^n} \frac {d\theta }{2\pi }=0

if

m
≠
n

m\ne n

, thus answering a question posed by Walter Rudin.