bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiple sclerosis and pregnancy
Authors: Lorenzi A R , Ford H L 
Published: October 2002

Abstract
Multiple sclerosis causes disability in young adults and, like most autoimmune diseases, affects women more commonly than men. The disease can therefore present at a time when many have, or are considering, starting a family. The effect of pregnancy on the outcome of multiple sclerosis is reviewed and the management of pregnant women who have multiple sclerosis is discussed.
The front-form Hamiltonian and BRST formulations of the JackiwRajaraman chiral Schwinger model
Authors: Kulshreshtha U , Kulshreshtha D S 
Published: October 2002

The Hamiltonian and BRST formulations of the JackiwRajaraman chiral Schwinger model are investigated in the light-front frame. PACS No.: 11.15-q
Quantum mechanics of the damped harmonic oscillator
Authors: Blasone M , Jizba P 
Published: October 2002

We quantize the system of a damped harmonic oscillator coupled to its time-reversed image, known as Bateman's dual system. By using the FeynmanHibbs method, the time-dependent quantum states of such a system are constructed entirely in the framework of the classical theory. The geometric phase is calculated and found to be proportional to the ground-state energy of the one-dimensional linear harmonic oscillator to which the two-dimensional system reduces under appropriate constraint. PACS Nos.: 03.65Ta, 03.65Vf, 03.65Ca, 03.65Fd
Diffusive behavior and structural characterization of a hard-sphere fluid through a narrow channel with roughened walls
Authors: Tafreshi H Vahedi , Benedek G , Zamankhan P , Sarkomaa P J 
Published: October 2002

A molecular dynamics technique is devised to simulate the flow of a hard-sphere fluid between two parallel roughened walls separated by a 10 particle diameter distance. The structural state of the system in different solid-volume fractions is characterized by analyzing the static-structure factor contour plot. At solids concentrations below [Formula: see text] [Formula: see text] 0.3, the calculations have shown no remarkable signature of the presence of the roughened confining walls similar to the previous unbounded simulation results (wide channel). At high concentrations, walls manifest their presence by reducing the particle diffusion in the direction of velocity gradient. Due to the metastability of the assembly, further increase in the solid fraction, [Formula: see text] [Formula: see text] 0.6, may yield a crystalline phase wherein diffusion coefficients vanish locally. PACS Nos.: 51.20+d, 61.20-p, 66.10Cb
First-quantized electron and photon model of QED and radiative processes
Authors: Yucel M B , Unal N 
Published: October 2002

In this study, we combine the classical models of the massive and massless spinning particles, derive the currentcurrent interaction Lagrangian of the particles from the gauge transformations of the classical spinors, and discuss radiative processes in electrodynamics by using the solutions of the Dirac equation and the quantum wave equations of the photon. The longitudinal-polarized photon states give a new idea about the vacuum concept in electrodynamics. PACS Nos.: 03.75-b, 11.10-z, 12.20-m, 13.40-f, 14.60Cd, 14.70Bh, 32.80Cy
Chemical effects on L X-ray intensity ratios of U and Th
Authors: Küçükönder A 
Published: October 2002

The chemical effects on the Lβ/Lα, Ll /Lα, and Lγ/Lα X-ray intensity ratios of U and Th were investigated. Vacancies were produced by heavily filtered 241Am gamma rays. A high-resolution Si(Li) detector system was used in the experiments. The experimental values are given with the theoretical values of the pure U and Th elements. PACS Nos.: 32.30Rj
Lowest order constrained variational and local density approximation approach to the hot alpha particle
Authors: Modarres M , Moshfegh H R , Mariji H 
Published: October 2002

The free energy of an alpha particle is calculated using the local density approximation in the harmonic oscillator basis. The effective two-body interactions are generated from the lowest order constrained variational (LOCV) calculation for nuclear matter at finite temperature, with the Reid and Δ-Reid potentials. The FermiDirac distribution is used to calculate the entropy and the occupation probability of each state of alpha particle at a given temperature. The effective mass is treated as a variational parameter. Our zero temperature results with the Δ-Reid interaction agree well with the experimental saturation data of alpha particle and the other many-body techniques. The flashing temperature of ≈5 MeV is found, which is consistent with experimental evidence. It is concluded that a similar liquidgas phase transition to that of nuclear matter is most probable in the alpha particle and heavier nuclei. PACS Nos.: 21.65+f, 21.10-k, 21.10Dr, 21.60-n
Squeezed Light Generation with 1.064 µm Nd:YAG Laser and 0.85 µm Single-Mode Fiber
Authors: Norihiko Nishizawa Norihiko Nishizawa , Satoshi Kume Satoshi Kume , Masakazu Mori Masakazu Mori , Toshio Goto Toshio Goto , Akira Miyauchi Akira Miyauchi 
Published: October 2002

Efficient squeezing at low pump light power is demonstrated with a mode-locked 1.064 µm Nd:YAG laser and a fiber ring reflector made of 0.85 µm single-mode fiber. Noise reduction of about 2.0 dB below the shot noise level is observed. The squeezing process by the optical Kerr effect is calculated with a simple model. The experimental results are in good agreement with the calculated ones.
Effect of Ge Concentration on Static and Microwave Performances in GexSi1-x Heterojunction Bipolar Transistors under High-Level Injection
Authors: Chyan Yih-Feng , Sze Simon Ming , Reif Chun-Yen Chang 
Published: October 2002

We report the theoretical investigation of the effect of Ge concentration on both static and high-frequency performances in polycrystalline silicon emitter Ge

x

Si1-
x

heterojunction bipolar transistors (HBTs). The calculation is carried out up to 0.95 V, before the onset of the Kirk effect [C. T. Kirk: IEEE Trans. Electron Devices ED-9 (1962) 164]. From this model, we find that the current gain, transconductance, cutoff frequency, and maximum oscillation frequency increase with increasing Ge concentration. In addition, the base transit time and the switching delay time in the emitter-coupled logic circuit slightly decrease as Ge content increases. Furthermore, it shows that the high-level injection effect becomes more pronounced in the Ge

x

Si1-
x

HBT as Ge concentration increases. Compared with the conventional low-level injection model, the improved model provides much more accurate expressions for electrical characteristics of Ge

x

Si1-
x

HBTs operating under high-level injection.
Photoluminescence from Localized Excitons in Si/Ge Superlattices
Authors: Joachim Hartung Joachim Hartung , Victor Higgs Victor Higgs , Gordon Davies Gordon Davies , E. C. Lightowlers E. C. Lightowlers , Vincent Arbet-Engels Vincent Arbet-Engels , K. L. Wang K. L. Wang 
Published: October 2002

Short period strained-layer Si/Ge superlattices grown by molecular beam epitaxy have been investigated by photoluminescence spectroscopy. In 16×4, 15×4 and 12×4 superlattices with 80 or 120 periods two new luminescence peaks appear. From their separation in photon energy, the two peaks are assigned to a no-phonon transition and its silicon transverse optical phonon replica. Detailed photoluminescence investigations have confirmed that the new peaks which appear at energies between 0.85 and 1.05 eV give evidence for radiative recombination in the superlattices. From their luminescence intensity as well as lineshape dependence on the excitation power we attribute the new peaks to localized excitons.
Thin-Film Bulk Acoustic Resonators Employing ZnO/Pyrex-Glass Composite Diaphragm Structure
Authors: Yoshiki Makishima Yoshiki Makishima , Ken-ya Hashimoto Ken-ya Hashimoto , Masatsune Yamaguchi Masatsune Yamaguchi 
Published: October 2002

This paper discusses the application of ZnO/Pyrex-glass composite diaphragm structure to thin-film bulk acoustic resonators (FBARs). Analysis of ZnO/Pyrex-glass composite diaphragm structure showed for thickness-longitudinal vibration that zero temperature coefficient of frequency with relatively large electromechanical coupling constant of about 20% is realised for the second- and third-order resonances as well as for the fundamental resonance. An FBAR employing the ZnO/Pyrex-glass composite diaphragm structure was fabricated, and Q values of 970 and 858 were obtained, respectively, for the fundamental and second-order resonances at 298.7 MHz and 497.5 MHz.
Analysis and Design of Magnetooptic Guided Wave Devices in Cerium-Doped Garnet Thin Films
Authors: Shin'ichiro Kikuchi Shin'ichiro Kikuchi , Yasumitsu Miyazaki Yasumitsu Miyazaki 
Published: October 2002

Optical devices using magnetostatic surface waves (MSSWs) have important applications in optical signal processing and optical computing. In this paper we propose the analysis and design of an optical mode conversion device that features improved properties. The device consists of cerium-doped thin and thick garnet films. The design features 100% mode conversion over an interaction length of about 5 mm for an applied microwave power density of a few mW/mm. The characteristics of optical wavelength filtering under a fixed biasing magnetic field are also investigated. The results can be used to construct an optical demultiplexer with wavelength separation as narrow as 2 nm in the wavelength band of 1.3 µm. The MSSW center frequency assumed in the calculation is f
c= 3.1504 GHz.
Alternating Magnetic Field Shielding of YBCO Tubes in Static Field
Authors: Soonchil Lee Soonchil Lee , Youngjo Go Youngjo Go , Dongyeon Won Dongyeon Won , Gyewon Hong Gyewon Hong , Sunchil Kwon Sunchil Kwon 
Published: October 2002

The alternating magnetic field shielding efficiency of a YBCO tube was measured in a static field of up to 1 kG, bearing the possibility of its application as a field regulator in mind. The shielding efficiency is higher when the sample is field-cooled than when it is zero-field-cooled, as predicted by the critical state model. In the case of field cooling, the tube still shields about 25% of ac field of 1 kHz even in 500 G dc field. Shielding efficiency monotonously increases with increasing frequency from 10 Hz to 1 kHz.
Influence of Interface Barrier on Lateral Transport Properties for Metal/Semiconductor Systems
Authors: Sekika Yamamoto Sekika Yamamoto , Tyuzi Ohyama Tyuzi Ohyama , Eizo Otsuka Eizo Otsuka , Syouichi Yamauchi Syouichi Yamauchi , Motohiro Iwami Motohiro Iwami 
Published: October 2002

This work reports on an investigation of the transport properties of metal semiconductor systems in the direction parallel to the interface. Anomalies caused by the shunting effect for resistivity and Hall coefficient measurement on metal semiconductor systems were analyzed in detail. It is found that the above-mentioned anomalies are closely related with the Schottky barrier height as well as the current density across the metal semiconductor interface. The critical temperature at which a distinct indication of the shunting effect appears is around 200 K for NiSi2/p-Si system.
High-Resolution Infrared Spectroscopy Applied to Powder Formation, Plasma Transport and Surface Processes
Authors: Boer Marco Haverlag , Gerrit Kroesen Gerrit Kroesen , Frits de Hoog Frits de Hoog 
Published: October 2002

Infrared absorption spectroscopy using both a Fourier transform spectrometer and a tunable diode laser arrangement has been performed to study the growth of particles in an rf (13.56 MHz) plasma at pressures from 25 to 200 mTorr in mixtures of CF4, CF2Cl2 and CHF3 with argon. A planar configuration has been used, with a silicon wafer on the powered electrode. Absorption bands at 750–1300 cm-1 have been found and attributed to C-F, Si-F, C-Cl and Si-C absorption. Furthermore continuous extinction due to Rayleigh and Mie scattering has been observed. The CF2 concentration appears to decrease strongly when powder growth begins. The SiF4 concentration shows a maximum then. Considering all these results, we arrive at the conclusion that particle growth is initiated by micromasking at the Si surface combined with a highly directional etching process. Due to residual isotropic etching the particles are released from the surface and enter the plasma. Furthermore, it has been found that the powder production continues and even accelerates after the freon flow is stopped, due to sputtering of remaining structures on the surface.
A Study of the Sustaining Mechanism in an Inductively Coupled Plasma
Authors: Kenji Kond Kenji Kond , Hidehiko Kuroda Hidehiko Kuroda , Toshiaki Makabe Toshiaki Makabe 
Published: October 2002

Inductively coupled plasma (ICP) has recently been of special interest in material processing reactors. We have developed a theoretical model based on the relaxation continuum (RCT) model for a collision-dominated ICP. The spatiotemporal behavior of ICP is investigated at 13.56 MHz in Ar under the crossed electric and magnetic fields. Electrons in time-varying electric and magnetic fields are transported in a complicated manner due to the appearance ofE×B-drift originating due to the Larmor motion. As a result, the electron energy gain and loss mechanism is controlled by the Larmor motion and the plasma is mainly sustained near the reactor wall during the phase when the external magnetic field is weakened. The space-time requirements for the maintenance of an ICP are investigated in terms of the net ionization rate and the electron flux.
Time-Resolved Measurements of RF Plasmas Using Electrostatic Probe Having Compensation Circuits for Space Potential Fluctuation
Authors: Takashi Tatsuno Takashi Tatsuno , Toshiki Taniguchi Toshiki Taniguchi , Shosaku Matsumura Shosaku Matsumura 
Published: October 2002

The time-resolved Langmuir probe method using a laser-heated emissive probe to compensate space potential fluctuation is modified to improve the limit of amplitude for compensation and reliability of current detection in order to experimentally study RF plasma under various conditions. Time-resolved electron temperatures and electron densities are measured at various input powers and pressures of Ar and He in 13.56 MHz RF asymmetric discharge. Not only the electron temperature but also the electron density change was synchronized with excitation RF. The period of variation is not the same as second harmonics, but is a fundamental period of 13.56 MHz. The electron temperature and the self-bias depend on the excitation RF power. Such evidence may indicate that plasma parameters are closely related with the electron acceleration in the electrode sheath and the plasma caused by the self-bias field.
Al–Pd–Re Icosahedral Quasicrystals and Their Low Electrical Conductivities
Authors: Yuko Honda Yuko Honda , Keiichi Edagawa Keiichi Edagawa , Akinori Yoshioka Akinori Yoshioka , Tatsuo Hashimoto Tatsuo Hashimoto , Shin Takeuchi Shin Takeuchi 
Published: October 2002

In the Al–Pd–Re system, two kinds of icosahedral phases (I-phases) with different quasilattice constants have been found to form at 1173 K. The I-phase with larger quasilattice constant is formed in a wide composition range at 1173 K: 13–25 at.%Pd and 10–15 at.%Re. The conductivity of single-I-phase samples varies greatly with the alloy composition and also from sample to sample for the same nominal composition, and is generally quite low; in some samples of Al70Pd20Re10 it is 0.5 Ω-1cm-1 at 4.2 K, the lowest value ever reported for quasicrystals. The magnetoconductivity at helium temperatures changes systematically with the conductivity value of the sample; it is negative at low temperature with its magnitude decreasing with decreasing conductivity and becomes positive for the lowest conductivity sample. The conductivity behavior cannot be interpreted either in the framework of the weak localization or in that of conventional variable range hopping.
Further Study on Temperature, Density, and Perturber Dependences of Absorption of 3.39 µm He-Ne Laser by Methane
Authors: Takao Tsuboi Takao Tsuboi , Ping Du Ping Du , Naoko Arimitsu Naoko Arimitsu , Jean-Michael Hartmann Jean-Michael Hartmann 
Published: October 2002

In order to supplement the information on the perturber dependence of absorption at 3.39 µm of the He–Ne laser by methane, the decadic molar extinction coefficients of methane diluted with helium, hydrogen and carbon dioxide have been measured. The broadening data S γ
l
( CH4–X)/ S γ
l
( CH4–Air) and β
l
( CH4–X) for He, H2 and CO2, which are available in a wide range of temperature (300–1000 K), are proposed.
Excess-Magnesia Effect on Pb(Mg1/2W1/2)O3–PbTiO3 Dielectrics and the Aging Phenomenon
Authors: Uchikoba Fumio , Oka Hitoshi , Tachimoto Kazushi , Takashi Ito Takashi Ito , Makoto Kobayashi Makoto Kobayashi 
Published: October 2002

The effects of 0 to 10 mol% excess-MgO addition on Pb(Mg1/2W1/2)O3–PbTiO3 (PMW-PT)
solid solutions were discussed. Excess-MgO addition successively changed the ferroelectric properties of PMW-PT. The
material showed relaxor-type behavior with excess-MgO addition, whereas stoichiometric composition showed
normal-ferroelectric-like properties, and further addition of 10 mol% caused dual peaks in the temperature
dependence of the dielectric constant. These dual peaks were found to be attributed to aging phenomena. The excess
MgO improved the degree of B-site ordering and local electric field based on defects, and it was suggested that the
B-site ordering and the local field were responsible for the relaxor property and the aging effect, respectively.
Photoacoustic Signals from Ion-Implanted and Epitaxially Grown Layers on Silicon Substrate
Authors: Ikari Tetsuo , Kouji Maeda Kouji Maeda , Koji Futagami Koji Futagami 
Published: October 2002

A nonradiative transition in ion-implanted and epitaxially grown layers on a Si substrate was measured by a piezoelectric photoacoustic (PA) spectroscopy. It is considered that the observed peak at 1.07 eV is caused by a nonradiative recombination of optically excited electrons from boron acceptor levels. The decrease of the 1.07 eV peak intensity by ion implantation is considered to be due to the formation of a surface damaged layer with deep defect levels. The PA spectra of epitaxially grown samples are well explained by summing the spectra of p- and n-type bulk samples. The electric field at the p-n junction may be effective in the PA signal generation mechanism in the higher photon- energy region.
New High-Tc Superconductor Family of Cu-Based Cu1-xBa2Can-1CunO2n+4-δ with Tc>116 K
Authors: Ihara Hideo , Tokiwa Kazuyasu , Ozawa Hirotomo , Hirabayashi Masayuki , Negishi Akira , Song Hirofumi Matuhata 
Published: October 2002

A new high-temperature and nontoxic superconductor family of Cu
1-x
Ba2Ca
n-1
Cu
n
O2n+4-δ with critical temperature (T
c)>116 K was discovered. These materials were prepared by the high-pressure technique. A superconductor sample with the highest T
c contains mainly a Cu1-
x

Ba2Ca3Cu4O12-δ phase. The T
c value of the Cu1-
x

Ba2Ca3Cu4O12-δ phase is 116.4 K. The phase has two kinds of tetragonal structures: body-centered tetragonal (bct) and simple tetragonal. The lattice parameters of bct are a=7.7114 Å and c=35.986 Å. The disordering or full occupation of Cu-vacancy sites leads to the simple tetragonal phase with the space group of P4/mmm and the half values of the lattice constants (a=3.8557 Å and c=17.993 Å) of the bct phase.
The relationship between the lattice constant c and the number of CuO2 layers n is c/2=8.4+3.2(n-1) ( Å). The small CuO2-block spacing (8.4 Å) of this family suggests a lower anisotropy and higher J
c than in Hg- and Tl-based superconductor families.
Double RF System for Suppression of Longitudinal Coupled Bunch Instability on UVSOR Storage Ring
Authors: Kazuhiro Tamura Kazuhiro Tamura , Toshio Kasuga Toshio Kasuga , Makoto Tobiyama Makoto Tobiyama , Hiroyuki Hama Hiroyuki Hama , Goro Isoyama Goro Isoyama , Toshio Kinoshita Toshio Kinoshita 
Published: October 2002

A third-harmonic cavity has been installed on the UVSOR electron storage ring in order to suppress longitudinal coupled bunch instability with a double RF system. The bunch length and the frequency spread of the synchrotron oscillation were increased with the double RF system, and the measured values at a low beam current were consistent with calculated ones. The longitudinal coupled bunch instability has been perfectly damped by Landau damping at the beam current of at least up to 300 mA.
Quantized Conductance of a Silicon Wire Fabricated by Separation-by-Implanted-Oxygen Technology
Authors: Yasuyuki Nakajima Yasuyuki Nakajima , Yasuo Takahashi Yasuo Takahashi , Seiji Horiguchi Seiji Horiguchi , Kazumi Iwadate Kazumi Iwadate , Hideo Namatsu Hideo Namatsu , Kenji Kurihara Kenji Kurihara , Michiharu Tabe Michiharu Tabe 
Published: October 2002

Ultra-fine silicon wires have been fabricated by SIMOX (Separation by IMplanted OXygen) technology, electron beam lithography, anisotropic chemical etching, and thermal oxidation. The silicon wires have a trapezoidal cross-sectional shape and are fully surrounded by SiO2, as confirmed by transmission electron microscopy. The size of the wires is controlled by using the fabrication method proposed here, as measured by scanning electron microscopy. A wire 20 nm wide and 6 nm high exhibits quantized conductance at 26 K, and conductance steps remain up to 60 K. In the case of a wire 17 nm wide and 4 nm high, steplike structures in the conductance versus gate voltage curve persist over 100 K. These results are attributed to the large subband energy spacing in the narrow wire region, where electrons are physically confined by the high potential of the SiO2 barrier.
Bloch Oscillations in Semiconductor Superlattices
Authors: Kö Hartmut G. Roskos , Heinrich Kurz Heinrich Kurz 
Published: October 2002

A brief summary of the time-resolved investigation of Bloch oscillations of electron wave packets in semiconductor superlattices is given. Focussing on the emission of coherent terahertz-frequency electromagnetic radiation by Bloch oscillations, new experimental and theoretical results are presented. In all experiments published so far, Bloch oscillations have been induced by simultaneous impulsive optical excitation of several excitonic Wannier-Stark states at the bandedge of the first electron miniband. Here, we report on the first observation of Bloch oscillations induced by photo-excitation of continuum states as high as 100 meV above the fundamental bandgap. We then address the feasibility of optically pumped Bloch (or Esaki-Tsu) oscillators as a practical source for electromagnetic signals with a frequency continuously tunable from several hundred GHz to at least 6 THz. Advantage is taken of the supperradiant character of the emission process. The emission efficiency is discussed and concepts for an increase of the output power are proposed.
Fuzzy Analysis of the Linear Equivalent for Fabricating a Holographic Optical Element in Photoresist
Authors: Seng Chang Rong , Pio Hu Chern Sheng Lin 
Published: October 2002

In this	paper	fuzzy analysis for economically fabricating a holographic optical element (HOE) in photoresist is conducted. We find that the grating profile has a close relationship with diffraction efficiency, and that the process parameters influence the grating profile significantly. Thus, using the fuzzy control in these relations, it becomes possible to predict the diffraction efficiency and to solve many problems in the grating fabrication process. From the modulation mechanism in these complex holograms we believe we have extracted the necessary and intrinsic qualities, and our model of fuzzy set analysis produces good general agreement with the experimentally measured diffraction efficiency. The new concepts of the “linear equivalent" which we established to simplify a HOE from a honeycomb structure to a linear one will be helpful for processing various types of HOEs.