bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite-element analysis of periodic piezoelectric transducers
Authors: Ballandras Sylvain , Wilm Mikaël , Edoa Paul-Francis , Soufyane Abdelaziz , Laude Vincent , Steichen William , Lardat Raphaël
Published: December 2002

The need for optimized acoustic transducers for the development of high-quality imaging probes requires efficient simulation tools providing reliable descriptions of the behavior of real devices. The purpose of this work is the implementation of a finite-element model for the simulation of periodic transducer arrays. By using the assumption of harmonic excitation, the harmonic admittance of the studied structure can be derived. It is then shown how the mutual admittance is deduced from this feature, allowing one to estimate the amount of cross-talk effects for a given periodic transducer. Computation results are reported for standard linear acoustic probes, 2-2 (one-dimensional periodic) and 1-3 (two-dimensional periodic) piezocomposite materials. In the case of 2-2 connectivity composites, a comparison between nonperiodic and periodic computations of the mutual admittance is conducted, from which the minimum number of periods for which periodic computations can be trustfully considered can be estimated.
Explicit formulas for effective piezoelectric coefficients of ferroelectric 0–3 composites based on effective medium theory
Authors: Wong C. K. , Poon Y. M. , Shin F. G.
Published: December 2002

Explicit formulas were derived for the effective piezoelectric stress coefficients of a 0–3 composite of ferroelectric spherical particles in a ferroelectric matrix which were then combined to give the more commonly used strain coefficients. Assuming that the elastic stiffness of the inclusion phase is sufficiently larger than that of the matrix phase, the previously derived explicit expressions for the case of a low volume concentration of inclusion particles [C. K. Wong, Y. M. Poon, and F. G. Shin, Ferroelectrics 264, 39 (2001); J. Appl. Phys. 90, 4690 (2001)] were “transformed” analytically by an effective medium theory (EMT) with appropriate approximations, to suit the case of a more concentrated suspension. Predictions of the EMT expressions were compared with the experimental values of composites of lead zirconate titanate ceramic particles dispersed in polyvinylidene fluoride and polyvinylidene fluoride-trifluoroethylene copolymer, reported by Furukawa [IEEE Trans. Electr. Insul. 24, 375 (1989)] and by Ng et al. [IEEE Trans. Ultrason. Ferroelectr. Freq. Control 47, 1308 (2000)] respectively. Fairly good agreement was obtained. Comparisons with other predictions, including the predictions given by numerically solving the EMT scheme, were also made. It was found that the analytic and numeric EMT schemes agreed with each other very well for an inclusion of volume fraction not exceeding 60%.
Piezoresistance measurement on single crystal silicon nanowires
Authors: Toriyama Toshiyuki , Funai Daisuke , Sugiyama Susumu
Published: December 2002

A p-type single crystal silicon nanowire bridge and a four-terminal nanowire element were fabricated by electron-beam direct writing. The piezoresistance was investigated in order to demonstrate the usefulness of these sensing elements as mechanical sensors. The longitudinal piezoresistance coefficient πl[110] was found to be 38.7×10−11 Pa−1 at a surface impurity concentration of Ns=9×1019 cm−3 for the nanowire bridge. The shear piezoresistance coefficient π44 was found to be 77.4×10−11 Pa−1 at Ns=9×1019 cm−3 for the four-terminal nanowire element. These values are 54.8% larger than the values obtained from p+ diffused piezoresistors, which are used in conventional mechanical sensors.
Kinetic modeling of nonlinear electron cyclotron resonance heating
Authors: Kamendje Richard , Kasilov Sergei V. , Kernbichler Winfried , Heyn Martin F.
Published: December 2002

A numerical method is proposed for modeling electron cyclotron resonance heating (ECRH) and current drive in fusion devices with, generally speaking, nonlinear wave–particle interaction. Considered is the case of second harmonic extraordinary wave resonance. The method is applied to model the electron distribution function in a simplified magnetic field geometry. Various combined effects of wave–particle interaction and Coulomb collisions are demonstrated. The model is compared to the bounce-averaged quasilinear Fokker–Planck equation for the case of perpendicular propagation of the wave beam with respect to the magnetic field. In addition, the absorption coefficients computed from these two models are compared to the results of both the linear and the adiabatic model. Significant differences between results are found for present-day ECRH power levels and fusion device parameters.
Constructing solutions of Hamilton–Jacobi equations for 2D fields with one component by means of Bäcklund transformations
Authors: Böttger Wulf , Wissowski Henning , Kastrup Hans A.
Published: December 2002

The Hamilton–Jacobi formalism generalized to two-dimensional field theories according to Lepage’s canonical framework is applied to several relativistic real scalar fields, e.g., massless and massive Klein–Gordon, Sinh and Sine–Gordon, Liouville and φ4 theories. The relations between the Euler–Lagrange and the Hamilton–Jacobi equations are discussed in DeDonder and Weyl’s and the corresponding wave fronts are calculated in Carathéodory’s formulation. Unlike mechanics one has to impose certain integrability conditions on the velocity fields to guarantee the transversality relations and especially the dynamical equivalence between Hamilton–Jacobi wave fronts and fields of extremals embedded therein. Bäcklund transformations play a crucial role in solving the resulting system of coupled nonlinear PDEs.
Radiation pressure and gas drag forces on a melamine-formaldehyde microsphere in a dusty plasma
Authors: Liu Bin , Goree J. , Nosenko V. , Boufendi L.
Published: December 2002

Measurements are reported for the radiation pressure and gas drag forces acting on a single melamine-formaldehyde microsphere. The radiation pressure force coefficient q, which would be unity if all incident photons were absorbed, has the value q=0.94±0.11. For argon, the Epstein gas drag force coefficient δ, which would be unity if impinging molecules underwent specular reflection, has the value δ=1.26±0.13 as measured with our single-particle laser acceleration method, or δ=1.44±0.19 as measured using the vertical resonance method.
Self-generation of hollow current profile and tilt instability in field-reversed configuration
Authors: Ohtani Hiroaki , Horiuchi Ritoku , Sato Tetsuya
Published: December 2002

Two-dimensional electromagnetic particle simulation is performed to investigate the profile relaxation from a magnetohydrodynamic (MHD) equilibrium to a kinetic one and the physical property of the kinetic equilibrium in the field-reversed configuration. The radial oscillation is excited in order to relax an excess energy in the MHD equilibrium. After this profile oscillation, the system spontaneously relaxes toward a kinetic equilibrium, in which the electron current profile becomes hollow as a result of the combined effects of the gradient-B drift near the field-null line and the E×B drift generated by the ion finite Larmor radius effect near the magnetic separatrix. On the other hand, the ion current profile becomes peaked due to the effect of the ion meandering orbit near the field-null line. The stability of the obtained kinetic equilibrium against the tilt mode is also studied by means of three-dimensional full electromagnetic particle simulation. It is found that the growth rate of the tilt instability in the case of the hollow current profile and high separatrix beta value is smaller than that in the case of the peaked current profile.
Fast wave current drive in the ion cyclotron frequency range from the single-particle point of view
Authors: Bilato R. , Brambilla M.
Published: December 2002

The quasilinear model is commonly used to determine the heating rate and the current drive efficiency of the fast wave in the ion cyclotron range of frequency. The validity of this model at these frequencies is a controversial issue [Bécoulet et al., Phys. Plasmas 1, 2908 (1994)]. Here this problem is addressed from the single-particle point of view by deriving an approximated Hamiltonian which accounts also for the inhomogeneity of the confining magnetic field. Realistic values of the wave field are calculated by means of the toroidal full-wave code TORIC for typical scenarios of an ASDEX Upgrade [Gruber et al., Nucl. Fusion 41, 1369 (2001)] experiment, and apply the Chirikov criterion to determine the threshold for the development of the intrinsic stochasticity. These results are verified by numerically integrating the Hamiltonian equations. It is found that, due to the discreteness of the parallel phase velocity spectrum of a fast wave at these frequencies, for the parameters of ASDEX Upgrade the intrinsic stochasticity is marginal, especially close to integer and low-rational values of the safety factor. The failure of intrinsic stochasticity to guarantee the validity of the conventional quasilinear model, however, does not imply the onset of nonlinear saturation in the power absorption and in the driven current, since in all realistic situations Coulomb collisions suffice, by a large margin, to ensure the applicability of the linearized Vlasov equation. Under this condition, power and momentum transfer rates to resonant electrons are identical to those predicted by the quasilinear theory.
Kinetic theory of spin transport in n-type semiconductor quantum wells
Authors: Weng M. Q. , Wu M. W.
Published: December 2002

We set up a set of many-body kinetic Bloch equations with spacial inhomogeneity. We re-examine the widely adopted quasi-independent electron model and show the inadequacy of this model in studying the spin transport. We further point out a new decoherence effect based on interference effect of electrons/spins with different momentum k along the direction of the diffusion, which is referred as “inhomogeneous broadening effect” in our paper. We show that this inhomogeneous broadening can cause spin decoherence alone even in the absence of the scattering and that the resulting decoherence can be more important than the dephasing effect due to the D’yakonov–Perel’ term together with the scattering. Our theory takes all the inhomogeneous broadening effect, the spin diffusion due to the spacial inhomogeneity and the spin dephasing into account and gets the results self-consistently. We further study the spin diffusion/transport of n-typed GaAs quantum wells in the steady state under different conditions, such as at different temperatures; in the presence of impurities; in the presence of external electric fields along the diffusion direction and/or the QW growth direction; and with magnetic fields in the Voigt configuration. We also demonstrate a time evolution of a spin package calculated from our many-body theory. Different features predicted from our many-body theory are highlighted in the paper.
Destabilization of nonlinear resistive wall mode due to suppression of poloidal rotation in a cylindrical tokamak
Authors: Sato M. , Hamaguchi S. , Wakatani M.
Published: December 2002

It is known that linear resistive wall modes (RWMs) can be stabilized by a poloidal rigid rotation. Nonlinear behavior of unstable RWMs has been studied in a cylindrical tokamak plasma with such a poloidal rotation. When a resistive wall is very close to the plasma surface (rw/a≃1.2) significant reduction of the poloidal rotation due to the Maxwell stress occurs in the neighborhood of resonant surface of (m,n)=(2,1), where m (n) is a poloidal (toroidal) mode number. Thus the nonlinear saturated state does not depend on the magnitude of poloidal rotation. However, when the resistive wall position is close to the ideal wall stabilization limit (rw/a=1.3) or rw/a≃1.27, the poloidal rotation remains in the nonlinear phase for a large poloidal rotation case. In this case, nonlinear saturation with a small amplitude level becomes possible. The role of Maxwell stress is clarified by introducing magnetic island width and rotational torque for the reduction of poloidal rotation.
Precise determination of fictive temperature of silica glass by infrared absorption spectrum
Authors: Kakiuchida Hiroshi , Saito Kazuya , Ikushima Akira J.
Published: December 2002

In silica glass, the peak position of infrared absorption spectrum at around 2260 cm−1, which is related to the average of distribution of Si–O–Si bonding angle, is useful for determining frozen-in temperature of glass structure, the so-called fictive temperature. We precisely determined relation between the peak position and fictive temperature up to 1550 °C and found that at fictive temperatures higher than 1400 °C the present relation differs from the relation which has been extrapolated from the previous data at fictive temperatures below 1400 °C. The peak position was found to simply shift to lower wave numbers with raising fictive temperature. This suggests that at fictive temperatures up to about 1600 °C there is no maximum in density, which has been reported to exist at around 1500 °C.
Ge/Si(100) islands: Growth dynamics versus growth rate
Authors: Capellini G. , De Seta M. , Evangelisti F.
Published: December 2002

The effect of the deposition rate on the size, density, and uniformity of Ge islands grown on Si(100) is investigated. Upon changing the growth rate from 4 to 110 ML/min the island density increases by one order of magnitude and the strained dome base decreases from 84 to 55 nm. A narrowing of the island size distribution was also observed. We discuss these experimental findings by taking into account island–island interaction effects.
Evidence of grain-boundary versus interface diffusion in electromigration experiments in copper damascene interconnects
Authors: Arnaud L. , Berger T. , Reimbold G.
Published: December 2002

In this work, evidence of copper diffusion paths is shown with fine scanning electron microscopy failure analysis after electromigration failures in single damascene interconnect structures. For the polycrystalline grain structures, it is established that grain-boundary diffusion occurred, although experimental electromigration activation energy values are ranging from 0.65 to 0.80 eV. Narrow lines with quasibamboo microstructures showed interface diffusion located at upper surface of Cu damascene e.g., SiN capping layer interface, with activation energy values ranging from 0.80 to 1.06 eV. Due to the compression stress state in copper under electromigration and oxide cracking, respectively, SiN cap debonding occurred at the upper corners of the damascene trench and resulted in copper extrusions. For both microstructures, this failure mode provided decreased extrapolated lifetimes. Electromigration experiments on two-level damascene test structures provided an upper limit of Blech length threshold product jLth<4000 A/cm. Our data are finally compared to available literature results and to studies on AlCu.
Inherent structures of crystalline pentacene
Authors: Della Valle Raffaele Guido , Venuti Elisabetta , Brillante Aldo , Girlando Alberto
Published: December 2002

Using a quasi-Monte Carlo scheme, we search the potential energy surface of crystalline pentacene to sample its local minima, which represent the “inherent” structures, i.e., the possible configurations of mechanical equilibrium. The system is described in terms of rigid molecules interacting through a standard atom–atom potential model. Several hundreds of distinct minima are encountered, with a surprising variety of structural arrangements. We find that deep minima are easily accessible because they exhibit a favorable energy distribution and their attraction basins tend to be wide. Thanks to these features of the potential surface, the localization the global minimum becomes entirely feasible, allowing reliable a priori predictions of the crystallographic structures. The results for pentacene are very satisfactory. In fact, the two deepest minima correspond to the structures of the two known experimental polymorphs, which are described correctly. Further polymorphs are also likely to exist.
Raman forward scattering of chirped laser pulses
Authors: Schroeder C. B. , Esarey E. , Shadwick B. A. , Leemans W. P.
Published: December 2002

Raman scattering of a high-intensity, short-duration, frequency-chirped laser pulse propagating in an underdense plasma is examined. The growth of the direct forward scattered light is calculated for a laser pulse with a linear frequency chirp in various spatiotemporal regimes. This includes a previously undescribed regime of strongly coupled four-wave nonresonant interaction, which is important for relativistic laser intensities. In all regimes of forward scattering, it is shown that the growth rate increases (decreases) for positive (negative) frequency chirp. The effect of chirp on the growth rate is relatively minor, i.e., a few percent chirp yields few percent changes in the growth rates. Numerical solutions based on a fully nonlinear cold Maxwell-fluid model are presented which confirm analytical predictions. Relation of these results to recent experiments is discussed.
The onset of dissipation in the kinematic dynamo
Authors: Thiffeault Jean-Luc , Boozer Allen H.
Published: December 2002

The kinematic regime of the magnetic dynamo neglects the backreaction of the magnetic field on the flow. For small magnetic diffusivity, in the early stage of evolution, there is an ideal phase where dissipative effects can also be neglected. The magnitude of the energy dissipation term is estimated (Ohmic heating), taking into account differential constraints on chaotic flows. The period of ideal evolution is roughly doubled over an estimate without constraints. The helicity generation terms are exponentially smaller than the energy dissipation, so that large quantities of energy are dissipated before any helicity can be created. Helicity flow is exponentially larger than net helicity generation. The constraints also lead to the existence of a singular initial condition for the magnetic field for which sizable amounts of helicity can potentially be created.
Photonic band gap effect in layer-by-layer metallic photonic crystals
Authors: Li Zhi-Yuan , El-Kady I. , Ho Kai-Ming , Lin S. Y. , Fleming J. G.
Published: December 2002

Theoretical models have been developed to investigate the reflection and transmission spectra, and photonic band structure for a midinfrared layer-by-layer metallic photonic crystal. It is found that photonic band gap effects due to global coupling between different unit cells in different layers play a key role in the formation of the lowest stop band gap extending to zero frequency and a high transmission passband adjacent to the stop band gap. Excellent agreement of theoretical results with experimental measurements is achieved.
Resonance properties of the quasi-one-dimensional Ising magnet [(CH3)3NH]CoCl3⋅2H2O in the paramagnetic and magnetically ordered phases
Authors: Kobets M. I. , Khatsko E. N. , Pashchenko V. A. , Chernyi A. S. , Dergachev K. G. , Borisenko V. G.
Published: December 2002

A study is made of the angular, frequency–field, and temperature dependences of the magnetic resonance of the quasi-one-dimensional Ising magnet [(CH3)3NH]CoCl3⋅2H2O in the paramagnetic phase. The experimental results obtained are explained in a model of spin-cluster resonance in a strongly exchange-coupled spin chain. The frequency–field dependences of the ferromagnetic resonance spectrum measured below the Néel temperature are studied for magnetic-field directions along the crystallographic axes a, b, and c. It is shown that for H→0 the spin-wave spectrum of this quasiferromagnet has two gaps (ν1=70.1 GHz and ν2=52.5 GHz).
Breakdown of the approximations of small perturbations in continuum modeling of amorphous thin film growth
Authors: Streng C. , Samwer K. , Mayr S. G.
Published: December 2002

Morphology evolution of thin film growth can be quantitatively modeled by employing rate equations for two-dimensional, single-valued functions within a treatment of small perturbations. This description can be expected to be valid in an intermediate film thickness regime, where substrate influences and three-dimensional effects are minor. The breakdown of the mathematical description in its upper film thickness limit is systematically investigated by a detailed comparison of experiments and simulation. Possible reasons for the failure are discussed and improvements are suggested.
Electrical detection of spin accumulation and spin precession at room temperature in metallic spin valves
Authors: Jedema F. J. , Costache M. V. , Heersche H. B. , Baselmans J. J. A. , van Wees B. J.
Published: December 2002

We have fabricated a multiterminal lateral mesoscopic metallic spin valve demonstrating spin precession at room temperature (RT), using tunnel barriers in combination with metallic ferromagnetic electrodes as a spin injector and detector. The observed modulation of the output signal due to the spin precession is discussed and explained in terms of a time-of-flight experiment of electrons in a diffusive conductor. The obtained spin relaxation length λsf=500 nm in an aluminum strip will make detailed studies of spin dependent transport phenomena possible and allow one to explore the possibilities of the electron spin for new electronic applications at RT.
F-enhanced morphological and thermal stability of NiSi films on BF2+-implanted Si(001)
Authors: Wong A. S. W. , Chi D. Z. , Loomans M. , Ma D. , Lai M. Y. , Tjiu W. C. , Chua S. J. , Lim C. W. , Greene J. E.
Published: December 2002

The morphological and thermal stability of conducting NiSi films formed on Si(001) are significantly enhanced by pre-implantation of the Si wafer with BF2+. In the absence of F, the maximum silicidation temperature Tmax is 650 °C; higher temperatures lead to the formation of the competing high-resistivity NiSi2 phase. Tmax, however, is increased to ⩾750 °C during NiSi formation on Si(001) implanted with 20 keV BF2+ at a dose of 5×1015 cm−2. The observed enhancement in NiSi thermal stability is due to F segregation to the silicide/Si(001) interface and silicide grain boundaries, which retards NiSi grain growth, leading to much smoother layers, and inhibits NiSi2 nucleation.
Surface band bending, nitrogen-vacancy-related defects, and 2.8-eV photoluminescence band of (NH4)2Sx-treated p-GaN
Authors: Lin Yow-Jon , Wang Zhi-Long , Chang Hsing-Cheng
Published: December 2002

We have employed the photoluminescence and x-ray photoelectron spectroscopy measurements to study the effects of (NH4)2Sx treatment on the p-type GaN (p-GaN). After (NH4)2Sx treatment, we found that the reduction of the surface state, related to nitrogen-vacancy defects on the p-GaN surface, led to a reduction in surface band bending by 0.25 eV. The surface band bending reduction and surface state reduction caused by the (NH4)2Sx surface treatment could be useful for the formation of ohmic and Schottky contacts between the metal and p-GaN layers. In addition, the intensity of the 2.8-eV photoluminescence band depended on the amount of nitrogen vacancy of p-GaN, which was also investigated in this study.
Fabrication of single- or double-row aligned self-assembled quantum dots by utilizing SiO2-patterned vicinal (001) GaAs substrates
Authors: Kim Hyo Jin , Motohisa Junichi , Fukui Takashi
Published: December 2002

We investigated the formation of In0.8Ga0.2As self-assembled quantum dots (SAQDs) grown on SiO2-patterned 1°, 2°, and 5°-off (001) GaAs substrates by selective area metalorganic vapor phase epitaxy technique. The SiO2 patterns were filled with various stripe opening windows along the misorientation direction of the substrates. During the growth of the GaAs buffer layer on the opening regions, the steps on the (001) top facet was affected by the widths of the (001) top facet and the misorientation angles of the substrates. Single- or double-row aligned In0.8Ga0.2As SAQDs having definite interval were successfully fabricated on the (001) top facet with optimized top width and periodicity of step bunching. These results indicate that the selective growth technique of SAQDs by utilizing SiO2-patterned vicinal substrates is promising for nanoelectronic device applications such as single-electron memory devices.
Piezoresponse force microscopy of lead titanate nanograins possibly reaching the limit of ferroelectricity
Authors: Roelofs A. , Schneller T. , Szot K. , Waser R.
Published: December 2002

Single ferroelectric lead titanate (PTO) grains down to 15 nm were fabricated by chemical solution deposition. Varying the dilution of the precursor solution leads to different grain sizes between 15 and 200 nm. The grain-size-dependent domain configuration was studied using three-dimensional piezoresponse force microscopy (PFM). It is found that the PTO grains in a dense film contain laminar 90° domain walls, whereas separated PTO grains show more complicated structures of mainly 180° domain walls. For grains smaller than 20 nm, no piezoresponse was observed and we suppose this could be due to the transition from the ferroelectric to the superparaelectric phase which has no spontaneous polarization. Recent calculations showed that the ferroelectricity of fine ferroelectric particles decrease with decreasing particle size. From these experiments the extrapolated critical size of PTO particles was found to be around 4–14 nm.
A simple algorithm for the transport of gamma rays in a medium
Authors: Arqueros F. , Montesinos G. D.
Published: December 2002

A simple Monte Carlo algorithm for the simulation of the passage of γ rays of about 1 MeV in a medium is presented. In this energy range the only relevant processes are Compton scattering and photoelectric absorption. The algorithm allows the visualization of the photon tracks as well as the calculation of many quantities of interest. Several problems for a layer and a cylinder are proposed. In particular, the energy transferred to electrons in a water cylinder as a function of depth and the line shape of a NaI scintillator is calculated.
Similarity between Grover’s quantum search algorithm and classical two-body collisions
Authors: Zhang Jingfu , Lu Zhiheng
Published: December 2002

By studying the diffusion operator in Grover’s quantum search algorithm, we find an analogy between quantum searching and classical, elastic two-body collisions. We exploit this mathematical analogy using a thought experiment involving multiple collisions between two bodies to help illuminate why Grover’s quantum search algorithm works. Related issues are discussed.
Patterns of Outcome and Prognostic Factors in Primary Large-Cell Lymphoma of the Testis in a Survey by the International Extranodal Lymphoma Study Group
Authors: Zucca E. , Conconi A. , Mughal T.I. , Sarris A.H. , Seymour J.F. , Vitolo U. , Klasa R. , Ozsahin M. , Mead G.M. , Gianni M.A. , Cortelazzo S. , Ferreri A.J.M. , Ambrosetti A. , Martelli M. , Thiéblemont C. , Moreno H. Gomez , Pinotti G. , Martinelli G. , Mozzana R. , Grisanti S. , Provencio M. , Balzarotti M. , Laveder F. , Oltean G. , Callea V. , Roy P. , Cavalli F. , Gospodarowicz M.K.
Published: December 2002

Purpose: To determine clinical features and patterns of outcome of primary testicular diffuse large B-cell lymphomas (DLCL).

Patients and Methods: A retrospective international survey of 373 patients with primary testicular DLCL.

Results: Most patients presented with localized disease (stage I to II), and the median age at diagnosis was 66 years (range, 19 to 91 years). Anthracycline-based chemotherapy was administered to 255 patients (68%), and prophylactic intrathecal chemotherapy was given to 68 patients (18%); 133 patients (36%) received prophylactic scrotal radiotherapy. Median overall survival was 4.8 years, and median progression-free survival was 4 years. The survival curves showed no clear evidence of a substantial proportion of cured patients. A favorable international prognostic index score (IPI), no B-symptoms, the use of anthracyclines, and prophylactic scrotal radiotherapy were significantly associated with longer survival at multivariate analysis. However, even for patients with stage I disease and good-risk IPI, the outcome seems worse than what was reported for DLCL at other sites. At a median follow-up of 7.6 years, 195 patients (52%) had relapsed. Extranodal recurrence was reported in 140 cases. Relapses in CNS were detected in 56 patients (15%) up to 10 years after presentation. A continuous risk of recurrence in the contralateral testis was seen in patients not receiving scrotal radiotherapy.

Conclusion: Testicular DLCL is characterized by a particularly high risk of extranodal relapse even in cases with localized disease at diagnosis. Anthracycline-based chemotherapy, CNS prophylaxis, and contralateral testicular irradiation seem to improve the outcome. Their efficacy is under evaluation in a prospective clinical trial.
Complete Freund's adjuvant immunization prolongs survival in experimental prion disease in mice
Authors: Tal Yuval , Souan Lina , Cohen Irun R. , Meiner Zeev , Taraboulos Albert , Mor Felix
Published: December 2002

We recently reported that immunization of mice with certain self‐prion protein peptides induced specific T‐cell and B‐cell immune responses; importantly, this immunization was associated with a decrease in the number of protease‐resistant PrPSc particles recoverable in a transplanted, scrapie‐infected syngeneic tumor. The present study was carried out to determine whether immunization with the immunogenic PrP peptides might influence the natural history of experimental scrapie in mice. We immunized C57BL/6 mice with self‐prion peptides in complete Freund's adjuvant (CFA) or with CFA alone as a control and then infected the mice with mouse‐adapted scrapie by injection either intraperitoneally or intracerebrally. We report here that immunization with CFA, irrespective of whether prion peptides were present in the inoculum, resulted in marked prolongation of survival of the mice, whether the challenge was intracerebral or intraperitoneal. Mice in the immunized and control groups that died contained equivalent amounts of PrPSc. Thus, CFA immunization has a therapeutic effect in experimental scrapie in mice, possibly by reducing the rate of PrPSc accumulation in the brain. © 2002 Wiley‐Liss, Inc.
High-Resolution Climate Simulations of Oxygen Isotope Stage 3 in Europe
Authors: Barron Eric , Pollard David
Published: December 2002

Oxygen isotope stage 3 (OIS 3) climate and its variations are the focus of the Stage 3 Project. The objective of the OIS 3 modeling effort is twofold: (1) to explore the importance of different boundary conditions on the climate of Europe and (2) to develop climate simulations that best reproduce the wealth of OIS 3 observations. Given the complexity of the topography and coastlines, the modeling effort is based on a “nested” General Circulation Model (GCM) and mesoscale model (RegCM2) with climate simulations for Europe on a 60-km grid spacing. The key conclusions are as follows: (1) The mesoscale model, driven by GCM output, does a reasonable job of reproducing the modern European climate. (2) OIS 3 variations in orbit, CO2, and ice-sheet size are of little significance in explaining the observed climate variability. (3) The model results focus attention on North Atlantic sea-surface temperatures (SST) as a major factor in explaining OIS 3 climates. (4) Experiments for different SST values capture a number of systematic changes in sea-level pressure and precipitation. (5) Climate models simulate substantial European cooling and significant changes in precipitation, but they do not explain large differences between OIS 3 warm and cold episodes.
Does F1‐ATPase subunit γ turn in the wrong direction?
Authors: Berzborn Richard J. , Schlitter Jürgen
Published: December 2002

Analyzing the direction of F1‐ATPase subunit γ rotation, its shape and non‐random distribution of surface residues, a mechanism is proposed for how γ induces the closing/opening of the catalytic sites at β/α interfaces: by keeping contact with the mobile domain of subunits β at the ‘jaw’ (D386, the seven consecutive hydrophobic residues and D394/E395), rotating γ works as a screw conveyer within the barrel of (α,β)3. Mutations of the conveyer contacts are predicted to inhibit. Rotating wheel cartoons illustrate enzyme turnover and conformational changes. Steric clashes, polar interactions and also substrate limitations lead to specific stops. Because it is constructed as a stepper, γ prevents uncoupling at high energy charge.
Risperidone in chronic schizophrenia: a detailed audit, open switch study and two-year follow-up of patients on depot medication
Authors: Conlon L , Fahy T.J , OˈToole R. , Gilligan J. , Prescott P.
Published: December 2002

Little information exists on the medium- to long-term outcome of switching patients with schizophrenia from traditional depot to atypical oral antipsychotic agents. By detailed clinical audit, we identified a representative group of 102 patients of an Irish psychiatric service with DSM-IV chronic schizophrenia and on depot neuroleptics for a mean of 15 years. Of 69 eligible to participate, 33 entered a 6-month switch study of risperidone, with limited follow-up of consenters and non-consenters at 1 and 2 years. At 6 months, 23 of 33 were still on risperidone and had small significant improvements in clinical and extrapyramidal side effects, QOL and adjunct medication measures over baseline. At 12 months, 19 of 33 were still on risperidone, reducing to 13 of 33 at 2 years. At 2 years, of 32 surviving consenters to switch, 19 had suffered clinically detrimental events and were no longer on risperidone, compared to none of the 33 surviving non-consenters, who were all still on depot. These findings suggest that switching from depot to risperidone may encounter high rates of refusal and attrition subsequent to switch. While a majority of switched patients may improve after to least 6 months, audit plus switch may have clinically unfavourable effects on others over a 2-year follow-up period.
On an Unusual Quantization Procedure of Heat Conduction
Authors: Gambár Katalin , Márkus Ferenc
Published: December 2002

We have shown in our previous works how to introduce the quantization procedure into the theory of heat conduction. In the present paper we point out where and why we need to complete the previous results to obtain the Hamiltonian by which we can bring “zero point” energy into the theory of thermal field. We calculate the energy and the quasi-particle number operator for heat conduction.
Investigating Some Spectral Properties of Two-Dimensional Hysteresis Play-Functionals
Authors: Ruffing Andreas
Published: December 2002

Spectral properties of two-dimensional generating functionals are considered. They are associated with scalar hysteresis operators. These operators occur as building elements for models of hysteresis within nonlinear analysis. We calculate eigenvalues of the hysteresis play-functionals and investigate the structure of the corresponding eigenvectors. It turns out that the point spectrum reflects the regularizing property that hysteresis play-operators exhibit in general: Their only possible eigenvalues are attained in the interval [0,1), thus reflecting the Lipschitz constant less than 1 for the play-operators.
A Limit Theorem for Quantum Markov Chains Associated to Beam Splittings
Authors: Liebscher Volkmar
Published: December 2002

We study special quantum Markov chains on a Fock space related to iterated beam splittings as introduced in [23]. Besides a characterization of the position distributions of the chain, we show some kind of weak convergence of such discrete time quantum Markov chains to a kind of continuous time quantum Markov process. Furthermore, we provide existence and uniqueness for the solution of a quantum stochastic differential equation related to this quantum Markov process both on an exponential domain and, on a larger domain, in a pointwise sense.
Benefits and Research in the Labour Market
Authors: Sinfield Adrian
Published: December 2002

‘Discussion of unemployment compensation by economists in the West is typically concerned with its negative aspects' (Micklewright, 1991, p. 419).’

‘A richer view of the relationship between unemployment and the labour market enables recognition of ‘some of the ways in which [benefits] may have a positive, rather than a negative, impact’ (Atkinson and Micklewright, 1991, p. 1722).’

This paper builds on one presented in Karlstad in June 1996 where I analysed the evidence on the disincentive effect of benefits in the 1994 OECD Jobs Study (Sinfield, 1997). In many respects that paper became a negative exercise, dwelling on the shortcomings in the disincentive evidence and its neglect of alternative evidence.

The present paper is directed towards a more positive objective. It attempts to measure up to C. Wright Mills' comment when he gave unemployment as his first illustration of the potential value of the sociological imagination: ‘both the correct statement of the problem and the range of possible solutions require us to consider the economic and political institutions of the society, and not merely the personal situation and character of a scatter of individuals’ (Mills, 1959, p. 123).
Characteristics of time-gated Raman amplification in GaP–AlGaP semiconductor waveguides
Authors: Tanabe T. , Suto K. , Saito T. , Kimura T. , Oyama Y. , Nishizawa J.
Published: December 2002

Time-gated Raman amplification in the GaP–AlGaP waveguide is investigated using mode-locked Ti–sapphire pump source with 80 ps pulse width. Logarithmic Raman gain linearly increases with increasing the pump power density as long as the gain is less than about 10 dB. However, with further increasing the pump power it becomes nearly proportional to the square root of the pump power density. This is due to the fact that the equivalent linewidth of the pump pulse is comparable to the spectral full width half maximum of the Raman gain coefficient (24 GHz). Another point is that the amplified pulse broadens as the waveguide length exceeds the optical length corresponding to the pump pulse width because Raman amplification occurs mainly due to backward scattering.
Surface roughening of recording media and readout performance of phase-change optical disk
Authors: Li J. M. , Shi L. P. , Miao X. S. , Lim K. G. , Tan P. K. , Meng H. , Chong T. C.
Published: December 2002

Scaling characteristics of the surface roughening of the phase-change optical media have been investigated. Studies have shown that the variation-correlation function of the surface profile of recording media follows an asymptotic power law. The influence of the film surfaces with different roughness on the readout performance of the optical media has been investigated based on a scalar diffraction model. The results show that only one roughness parameter cannot reflect the responding readout properties of a phase-change optical disk such as signal noise and jitter due to the surface roughening. Fractal Brownian motion is applied to simulate the scaling characteristics of the surface roughening. Influence of the surface roughening with different Hurst exponents on the readout performance of the optical media has been studied. Results of the numerical calculation from both simulated and physical surfaces of the phase-change media show that the surface roughening with a lower Hurst exponent will cause a higher deterioration of the detected signals. Therefore, the fractal method provides an effective approach to the failure analysis of the optical phase-change disk.
Particle diffusion in random fields: Time-nonlocal description and numerical simulations
Authors: Zagorodny A. , Zasenko V. , Weiland J. , Holod I.
Published: December 2002

The theory of time-nonlocal random processes formulated in terms of the non-Markovian Fokker–Planck equation is used to describe the results of numerical simulations of particle diffusion in the random longitudinal field with given statistical properties. The simulations of particle motion were performed for the wide range of particle velocity and random field parameters. It is confirmed that conventional quasilinear theory in the approximation disregarding the time and velocity dependence of the diffusion coefficient in the velocity space can be used only in the case of small intensity and large width of turbulent field spectrum. The increase of the intensity as well as the decrease of the spectral width lead to considerable deviation of the results of simulations (such as saturation and frequent oscillation of the mean-square velocity displacement) from the predictions of the quasilinear theory. It is shown that in the case of small intensities these deviations can be successfully described in terms of non-Markovian generalization of the quasilinear approximation. In the case of high field intensity the description of these features would require more consistent account for the diffusion coefficient velocity dependence and time-nonlocal effects.
Transient current generation during wear of high-density polyethylene by a stainless-steel stylus
Authors: Wasem J. V. , Upadhyaya P. , Langford S. C. , Dickinson J. T.
Published: December 2002

Contact electrification between metals and insulators lead to dramatic transient charge transfer phenomena during sliding contact. We report simultaneous transient current and lateral force measurements as a stainless-steel stylus is drawn across a high-density polyethylene surface in vacuum. Stylus motion in this system is marked by unstable transitions between high and low velocity modes, similar to stickslip. The high velocity events coincide with falling lateral forces and high current signals. Scanning electron microscope images of the resulting wear tracks show slip-related features at intervals consistent with the lateral force and current fluctuations. Although average charge densities along the wear track ranged from 0.4−1 mC/m2, measurements at low normal forces are consistent with higher charge densities (up to 3 mC/m2) at isolated asperity contacts. Current transients as short as 60 μs were observed with total charges consistent with the detachment of 40×40 μm2 contact areas.
Shear Alfvén resonances in line-tied geometries near magnetic neutral lines and nulls
Authors: Albright B. J. , Cowley S. C.
Published: December 2002

One of the outstanding challenges of solar physics is understanding the mechanism for heating the solar corona, a low-β, low-resistivity plasma driven slowly by the shuffling of “footpoints” (ends of flux tubes) anchored in the photosphere. The corona’s low resistivity means that enormous current densities must be present for Ohmic dissipation to be effective. Two ways that this can occur in a slowly evolving, “quasiequilibrium” medium are by the formation of current sheets or by the excitation of very low-frequency Alfvén resonances. Both processes lead to singular current densities in the ideal limit, and both may result from the excitation of very low- (or zero-) frequency shear Alfvén resonances. Thus, understanding the conditions under which zero-frequency Alfvén resonances can occur may ultimately be important in understanding coronal heating. This paper examines shear Alfvén resonances in line-tied magnetic geometries, with special attention being paid to geometries with discontinuities in the field line mapping as candidates for having zero-frequency Alfvén resonances. Two such geometries have been examined in detail: a two-dimensional X-point and a three-dimensional magnetic null. Qualitative differences in the two spectra are observed. The X-point geometry has Alfvén resonances of vanishing frequency, whereas the magnetic null geometry has a finite cutoff in resonant frequency for all field lines in the system. The Alfvén continuum for a null depends on its geometry, however, and much lower (though still nonzero) resonant frequencies are found when the flux surfaces are moderately eccentric. Consequently, a subset of magnetic nulls in complex, line tied geometries may have flux surfaces that can be driven resonantly by a driver of much lower frequency than for similar media without nulls. To the extent that nulls are generic features of complex magnetic geometries {and there is some reason to suspect that they are [Albright, Phys. Plasmas 6, 4222 (1999)]} this result may resolve one of the unsettled difficulties with Alfvén heating models of the solar corona.
Competing multistability in a plasma diode
Authors: Hahn S. J. , Pae K. H.
Published: December 2002

The competing multistability in a plasma diode system has been demonstrated numerically. This system exhibits the time-dependent, competing behavior between multistable coexisting attractors for the same set of parameters with an extreme sensitivity to the initial conditions. By employing the one-dimensional particle-in-cell simulations, the multistability and the competition between multiple attractors have been investigated in the space of well-defined relevant parameters of a plasma diode system.
Microfocus x-ray study of selective area epitaxy of SiGe on Si
Authors: Giannakopoulos K. P. , Roth S. , Burghammer M. , Fellous C. , Richard D. , Dutartre D.
Published: December 2002

We describe an x-ray microprobe measurement of selectively grown heteroepitaxial Si1−xGex on Si. The experiment was conducted at the European Synchrotron Radiation Facility of Grenoble at the ID13 Microfocus beamline. The Si1−xGex layers were deposited by a standard chemical vapor deposition process on patterned 200 mm wafers of monocrystalline Si substrate. The uniformity of the pseudomorphic layers, in terms of Ge content and thickness, is evaluated by double crystal x-ray diffraction with the use of a novel microgoniometer and with a spatial resolution of ∼5×7.5 μm2. The results show the good uniformity of the SiGe layers and indicate the possibility of evaluating the strain fields near the shallow trench isolation structures.
Response to “Comment on ‘Study on the quantum efficiency of resonant cavity enhanced GaAs far-infrared detectors”’ [J. Appl. Phys. 93, 786 (2003)]
Authors: Luo H. T. , Zhang Y. H. , Shen W. Z.
Published: December 2002

In this response, we present reasons showing that our method is usually reasonable in device application due to its good approximation. A standard transfer matrix method has also been suggested to solve the issue concerning the interface reflection.
Relation between photoreflectance excitation and absorption spectra for GaAs and GaN films
Authors: Behn U. , Brandt O. , Grahn H. T.
Published: December 2002

Photoreflectance excitation (PRE) spectroscopy is shown to be a suitable method to investigate semiconductor materials in the near-infrared to near-ultraviolet spectral range. The investigation of a GaAs and a GaN bulk film demonstrates the applicability of this method even up to room temperature. For both materials, the line shape analysis suggest a nonlinear relation between the PRE and the absorption line shapes, leading to a reduction of the excitonic peak height in the PRE spectra compared to the absorption spectra. To keep this reduction as small as possible, the pump power should be on the order of the probe power or smaller.
Viscoelastic analysis of hydrostatic pressure induced optical effects in double-coated optical fibers
Authors: Chang Win-Jin
Published: December 2002

The microbending losses and refractive index changes of double-coated polymeric optical fibers induced by hydrostatic pressure are studied by viscoelastic analysis. The results obtained by using the Laplace transfer method, the linear viscoelastic–linear elastic correspondence principle, and the compatibility conditions of displacement at the interfaces are presented. It is presented that the results obtained by viscoelastic analysis can be reduced to those obtained by using elastic analysis. The materials of the polymer coatings should be properly selected in order to minimize microbending losses and refractive index changes. It will also be presented that microbending losses and refractive index changes decrease with a decrease in the Young’s modulus and Poisson’s ratio of the primary coating in conjunction with an increase in the elastic constants of the secondary coating.