bluuebunny/crossref_metadata_2025 huggingface dataset:
ELECTRONIC STRUCTURES OF La0.7Ca0.3MnO3 AND La0.7Ce0.3MnO3 BY X-RAY ABSORPTION SPECTROSCOPY
Authors: ASOKAN K. , RAO K. V. R. , JAN J. C. , CHIOU J. W. , PONG W. F. , KUMAR RAVI , HUSAIN SHAHID , SRIVASTAVA J. P.
Published: October 2002

Electronic structures of hole-doped and electron hole-doped manganites, La 0.7 Ca 0.3 MnO 3 and La 0.7 Ce 0.3 MnO 3, have been elucidated by X-ray absorption near-edge structure (XANES) spectra of O K- and Mn L3,2-edges. In the electron-doped system, La 0.7 Ce 0.3 MnO 3, the spectral features of O K-edge spectra are shifted by ~ 1 eV towards the higher energy side and reduction of Mn valency from 4+ and 3+ to 3+ and 2+ is expected when compared to hole-doped manganite. The XANES of Ce M5,4-edges indicates a tetravalent state for Ce, similar to that in CeO 2. Ce 4+ is incorporated into the lattice of LaMnO 3, resulting in the modification of MnO 6 octahedra and also indicating strong hybridization of Ce 5d and/or Ce 4f states with O 2p states.
PHOTOEMISSION STUDY OF QUASI-ONE-DIMENSIONAL HALOGEN-BRIDGED COMPOUND [Ni(chxn)2Br]Br2
Authors: FUJIMORI SHIN-ICHI , INO AKIHIRO , OKANE TESTUO , FUJIMORI ATSUSHI , OKADA KOZO , MANABE TOSHIO , YAMASHITA MASAHIRO , KISHIDA HIDEO , OKAMOTO HIROSHI
Published: October 2002

We report results of the angle-resolved photoemission experiments on a quasi-one-dimensional halogen-bridged complex [Ni(chxn) 2 Br]Br 2 ( chxn = 1R, 2R-cyclohexanediamine), which is a one-dimensional Heisenberg spin chain with S = 1/2 and J ~ 3600 K . The expected two dispersions, originated with spin–charge separations as have been observed in other quasi-one-dimensional electron systems like Sr 2 CuO 3, are not clearly observed in this compound. Instead, only one 'band" having about 0.5 eV energy dispersion is found in the half of the Brillouin zone.
TEMPERATURE-DEPENDENT HIGH-RESOLUTION PHOTOEMISSION SPECTROSCOPY OF YbXCu4 (X=In, Cd, Mg)
Authors: SATO H. , NISHIKAWA Y. , NAGASAKI F. , FUJINO H. , TAKEDA Y. , ARITA M. , SHIMADA K. , NAMATAME H. , KIMURA A. , TANIGUCHI M. , HIRAOKA K. , KOJIMA K.
Published: October 2002

Valence-band and Yb 4d photoemission spectra of YbXCu 4 (X=In, Cd, Mg) have been measured with high energy resolution from 10 to 300 K. In the valence-band photoemission spectra of YbInCu 4 and YbCdCu 4, the structure due to the Yb 2+ 4f 7/2 states is clearly observed near the Fermi level (E F ) at 10 K. The intensity of the Yb 2+ 4f 7/2 structure decreases with increasing temperature and the structure almost disappears at 300 K. The amount of the enhancement from 50 to 107 K is much stronger for YbInCu 4 than for YbCdCu 4. On the other hand, the Yb 2+ 4f 7/2 structure of YbMgCu 4 is observed as a broad peak near E F and the spectra show little temperature dependence. In the Yb 4d photoemission spectra of YbInCu 4 and YbCdCu 4, the structures due to the Yb 2+ and Yb 3+ states are recognized. The intensity ratio Yb 2+/ Yb 3+ increases with decreasing temperature. In the Yb 4d spectra of YbMgCu 4, on the other hand, almost only structures due to Yb 2+ states are observed.
HIGH FREQUENCY LIMITS OF THE TWO-ELECTRON PHOTOIONIZATION CROSS SECTIONS
Authors: KRIVEC R. , YA. AMUSIA M. , MANDELZWEIG V. B.
Published: October 2002

Several cross sections of two-electron processes at high but nonrelativistic photon energies ω are considered, which are expressed solely via the initial state wave function of the ionized two-electron object. The new high precision and locally correct nonvariational wave functions describing the ground and several lowest excited states of H -, He and helium-like ions are used in calculations of different cross sections in the pure dipole approximation and with account of first order corrections in ω/c2, and a number of the cross sections' ratios. The dependencies of all these quantities on the nuclear charge Z and the principal quantum number n (for 1 < n < 5) of the initial state excitation are studied.
INFLUENCE OF OPTICAL PROPERTIES ON THE SPIN POLARIZATION OF Cu3P PHOTOELECTRONS
Authors: CHASSÉ A. , NIEBERGALL L.
Published: October 2002

We have investigated the influence of optical properties of Cu(001) on the spin polarization in Cu 3p photoelectron diffraction patterns. The refraction and absorption of light have been taken into account in the calculation of the dipole transition matrix element. Therefore, a general polarization vector of light is defined within a macroscopic theory of electromagnetic fields.

Results are shown and discussed for Cu 3p photoelectrons excited by linearly or circularly polarized light, respectively. It is shown that the optical behavior of crystals may cause a symmetry breaking in the angular dependence of the photoelectron intensity. Besides, there are strong quantitative changes in the related spin polarization of Cu 3p photoelectrons.
CALCULATION OF THE RESONANT MAGNETO-OPTICAL PROPERTIES OF TRANSITION METALS AND DISORDERED ALLOYS IN THE X-RAY REGIME
Authors: MINÁR J. , EBERT H.
Published: October 2002

A version of the Kubo formula is presented, which allows one to calculate the resonant magneto-optical properties in the X-ray regime for arbitrary materials. This is achieved by representing the underlying electronic structure in terms of the electronic Green's function. Calculating the Green's function within the framework of spin-polarized relativistic multiple scattering theory (SPR-KKR) in particular gives access to spin–orbit-induced resonant magneto-optical properties. Results obtained for the Faraday effect and for the magnetic dichroic part of the complex reflective index n at the K-edge of Co and L 2,3-edges of Fe are found in very good agreement with recent experimental findings. The relation of n with the local magnetic moment is discussed on the basis of the calculated results for the L 3-edges of Pt in fcc-Co x Pt 1-x disordered alloy.
RELATIVISTIC CALCULATION OF POLARIZATIONAL BREMSSTRAHLUNG SPECTRA
Authors: KOROL A. V. , SOLOVJEV I. A. , OBOLENSKY O. I. , SOLOV'YOV A. V.
Published: October 2002

A formalism for the full relativistic treatment of the polarizational bremsstrahlung formed in collision of a charged particle with a many-electron target is developed. The multipole series for amplitude and cross section are evaluated. The presented results of numerical computation of polarizational bremsstrahlung cross sections and angular distributions show the importance of the relativistic and higher-multipole effects in the case of relativistic collision with a high-Z target. The logarithmic growth of relativistic cross section with increasing incident energy is demonstrated. The calculations are performed on the basis of the nonrelativistic and relativistic algorithms and compared with each other and with available experimental data.
RESONANT X-RAY SCATTERING IN YTiO3 AND YVO3
Authors: TAKAHASHI MANABU , IGARASHI JUN-ICHI
Published: October 2002

We investigate the Ti and V K edge resonant X-ray scattering spectra in YTiO 3 and YVO 3 by using ab initio band structure calculation based on the local density approximation. The calculated spectra show good agreement with recent experiments, although the effect of the orbital ordering is neglected, while that of the lattice distortion is taken into account in the calculation. Particularly, the observed drastic change of the spectra for the (100) reflection between the low temperature and intermediate temperature phases of YVO 3 is nicely explained by the difference of the Jahn–Teller distortion between the two phases. These results cast doubt on an assertion that the resonant X-ray scattering is a direct observation of the orbital order in YTiO 3 and YVO 3.
MULTIPLE SCATTERING THEORY OF PHOTOELECTRON ANGULAR DISTRIBUTIONS FROM ORIENTED DIATOMIC MOLECULES
Authors: DÍEZ MUIÑO R. , ROLLES D. , DE ABAJO F. J. GARCÍA , FADLEY C. S. , VAN HOVE M. A.
Published: October 2002

We use multiple scattering photoelectron diffraction (MSPD) theory to calculate the angular patterns of electrons photoemitted from the K-shell of CO and N 2 gas-phase oriented molecules, as recently measured by several groups. For low (E < 50 eV ) kinetic energies of the photoemitted electron, the electron scattering cannot be adequately represented by spherically symmetric potentials. We thus include nonspherical scattering potentials in our formalism through nondiagonal scattering matrices. We show that intramolecular scattering and interference are responsible for the experimentally measured patterns. This MSPD approach represents a more accurate and versatile method for dealing with such angular distributions as compared to prior calculations of these effects.
HIGH-RESOLUTION Si2p CORE-LEVEL STUDY OF THE K/Si(111)-(3 × 1) SURFACE
Authors: SAKAMOTO KAZUYUKI , ZHANG H. M. , UHRBERG ROGER I. G.
Published: October 2002

The structure of the K/Si (111)-(3 × 1) surface was studied by high-resolution core-level photoelectron spectroscopy. Five surface components were observed in the Si 2p core-level spectra. Compared to the bulk component, three components are shifted to lower and two to higher binding energies. The two components with the lowest binding energies are assigned to the top-layer Si atoms bonded to the K atoms with different configurations. The component with highest binding energy has a contribution from the π-bonded Si atoms of the top layer. The two other components originate from the Si atoms of the second and third layers.
SURFACE-PHOTOVOLTAGE EFFECT IN A GaAs–GaAsP SUPERLATTICE STUDIED WITH COMBINATION OF SYNCHROTRON RADIATION AND THE LASER
Authors: TANAKA SENKU , MORÉ SAM D. , TAKAHASHI KAZUTOSHI , KAMADA MASAO , NISHITANI TOMOHIRO , NAKANISHI TSUTOMU
Published: October 2002

Core-level photoelectron spectroscopy with the combination of synchrotron radiation (SR) and a laser was used for exploring the surface-photovoltage (SPV) effect and its temporal profiles in a GaAs–GaAsP superlattice (SL). It was observed that the SPV value in the SL is suppressed as compared with a bulk GaAs. However, no significant difference was found in the temporal profile between the bulk and the SL. It is suggested that the suppression of the SPV in the SL is dominantly due to the small value of band bending under thermal equilibrium.
QUASIPARTICLE SCATTERING PROCESSES IN A MODEL FERMI LIQUID: 1T-TiTe2
Authors: PERFETTI L. , ROJAS C. , REGINELLI A. , GAVIOLI L. , BERGER H. , MARGARITONDO G. , GRIONI M.
Published: October 2002

We performed angle-resolved photoelectron spectroscopy (ARPES) and resistivity measurements on the layered metal 1T-TiTe 2. We determined the quasiparticle dispersion and lifetime. In particular, we could characterize and separately evaluate the effects of the electron–electron and electron–phonon interactions on the experimental spectra. The good correlation between transport and spectroscopic scattering rates indicates that this material behaves as a model Fermi liquid system.
HIGH-RESOLUTION ANGLE-RESOLVED PHOTOEMISSION STUDY OF BaCo1-xNixS2
Authors: SATO T. , KUMIGASHIRA H. , IONEL D. , ITO T. , TAKAHASHI T. , HASE I. , DING H. , CAMPUZANO J. C. , SHAMOTO S.
Published: October 2002

We have performed angle-resolved photoemission spectroscopy on a layered Mott system BaCo 1-x Ni x S 2 across the phase transition from the antiferromagnetic insulator (x = 0.18) to anomalous metal (x = 0.28). In the anomalous metallic phase, we found a large Fermi surface centered at the M(A) point with a dominant Co (Ni) 3d3z2-r2 character. Hubbard bands in the insulating phase have a remnant of Fermi surface in the metallic phase and gradually evolve into metallic dispersive bands upon carrier doping. We conclude that the electronic structure of BaCo 1 - x Ni x S 2 is basically different from that of the high-Tc cuprates although the transport and magnetic properties share some common features between the two layered compounds.
EXCITONIC SIDE BANDS OF INNER-SHELL EXCITATIONS IN RARE GAS SOLIDS
Authors: VIELHAUER S. , KIRM M. , KISAND V. , NEGODIN E. , SOMBROWSKI E. , STEEG B. , ZIMMERER G.
Published: October 2002

Valence-exciton luminescence under inner-shell excitation of the rare gas solids Xe, Kr, and Ar has been measured using time-resolved photoluminescence. Two different processes for exciton creation can be distinguished: creation of "prompt" excitons immediately after excitation (within the experimental time resolution), and creation of "delayed" excitons through electron–hole recombination. The decay structure of the exciton emission in the range of inner-shell excitation is characterized by the coexistence of the two processes. Time-resolved excitation spectra near the 2p edge in Ar, the 3d edge in Kr, and the 4d edge in Xe are discussed. The process of prompt exciton creation is strongly enhanced above an excitation threshold at the energy position of the ionization limit of the core state plus the energy of the valence free exciton.
OPTICAL ABSORPTION AND LUMINESCENCE OF C60F2X COMPOUNDS
Authors: DUDIN P. V. , AMARANTOV S. V. , STANKEVITCH V. G. , BEZMELNITSYN V. N. , RYZKOV A. V. , BOLTALINA O. V. , DANAILOV M. B.
Published: October 2002

We have investigated the reduction of initial C 60 electronic structure under the influence of a growing number of attached fluorines in C 60 F 48, C 60 F 36, C 60 F 24, and C 60 F 18. The reduction of the low-energy π-electron subsystem reveals itself in lowering of the optical absorption in the visible region and in gradual blueshift of the luminescence. The absorption of C 60 F 24 and C 60 F 18 films strongly resembles that of C 60, thus showing the similarity of electronic structures of C 60 and these compounds. This resemblance disappears in the absorption spectra of C 60 F 48 and C 60 F 36. The absorption of these compounds looks like that of C 6 H 6, because the π-bonds are isolated.

The luminescence of C 60 F 18 film has an unexpected two-component structure, with the first component close to the C 60 luminescence spectra, and the second one lying pproximately in the same region with C 60 F 36. We attribute this splitting of luminescence spectra to the two different channels for relaxation of the electronic excitation. The first one is correlated with the fluorinated part of the C 60 F 18 molecule, the second one with the part free of fluorine atoms.
LOCAL ELECTRONIC STRUCTURE OF DOPING ATOMS IN MA2Can-1CunO2n+3 HIGH-Tc SUPERCONDUCTORS WITH [M-12(n-1)n] TYPE STRUCTURES
Authors: KURMAEV E. Z. , MOEWES A. , ZHIGADLO N. D. , TAKAYAMA-MUROMACHI E. , NEKRASOV I. A. , BUREEV O. A. , WOODS G. T. , CALLCOTT T. A. , YARMOSHENKO YU. M. , SHAMIN S. N. , EDERER D. L. , YANAGIHARA M.
Published: October 2002

Results of X-ray fluorescence measurements of MA 2 Ca n-1 Cu n O 2n + 3 compounds with [ M -12(n-1)n] type structures, ( C 0.8 N 0.2 Sr 2 CuO 5.3, [ Cu 0.25 (C,N) 0.75] Sr 2 CaCu 2 O y, Cu 0.5 V 0.5 Sr 2 CaCu 2 O 7.5, Cu 0.5 V 0.5 Sr 2 Ca 2 Cu 3 O 9.4, Cu 0.5 V 0.5 Sr 2( Ca 3.6 Sr 0.4) Cu 5 O 13.5 and Cu 0.5 V 0.5 Sr 2( Ca 4.7 Sr 0.3) Cu 6 O 15.3, are presented. The experiments show that C-atoms form a distorted CO 3 oxyacid group with a partial substitution of copper and nitrogen atoms in the M-sites. We conclude that the CO 32- group in (C,N) Sr 2 Ca n-1 Cu n O y and (Cu,C,N) Sr 2 Ca n-1 Cu n O y is substituted by the NO 2- which induces the creation of the hole carriers in these compounds. We have found that V-atoms in the given compounds form ( VO 4)3- tetrahedrons and have a pentavalent state.
CATION AND ANION ELECTRONIC EXCITATIONS IN MgO AND BaF2 CRYSTALS UNDER EXCITATION BY PHOTONS UP TO 75 eV
Authors: KIRM M. , VIELHAUER S. , ZIMMERER G. , LUSHCHIK A. , LUSHCHIK Ch.
Published: October 2002

The creation of primary and secondary cation excitations was investigated for MgO and BaF 2 crystals using the energy-and time-resolved luminescence method. It was shown that the primary cation excitations in MgO created by photons of 50–65 eV decay with the formation of anion free excitons and electron–hole pairs. The formation of secondary cation holes by hot photoelectrons in the Ba 2+ 5p shell causes the increase of cross-luminescence intensity whereas the creation of neither primary nor secondary cation excitons causes the appearance of cross-luminescence in BaF 2.
QUANTUM-WELL STATES OF sp AND d CHARACTER IN ULTRATHIN EPITAXIAL Ag AND Au FILMS ON W(110)
Authors: SHIKIN A. M. , RADER O. , GUDAT W. , PRUDNIKOVA G. V. , ADAMCHUK V. K.
Published: October 2002

Using angle-resolved photoemission, we observe quantum-well-state formation as pronounced peaks up to large thicknesses in epitaxial Ag and Au films on W(110). These systems serve as a test case for the assignment of sp and d orbital character to quantum-well states since overlap of sp with d states is strong for both systems but differs in detail. Starting out from peak assignments on the basis of the extended phase accumulation model, the angle dispersion of several features is discussed in detail and related to the orbital character.
SCATTERING OF ELASTIC WAVES BY THE ISOLATED LINEAR CHAIN OF PHYSISORBED ATOMS ON THE SURFACE IN A TWO-DIMENSIONAL WAVEGUIDE
Authors: TAMINE M.
Published: October 2002

The scattering and transmission properties of vibrational waves in a perturbed two-dimensional wave-guide in the harmonic approximation are presented. The perturbation is characterized by an isolated adatom defect boundary separating two planar waveguide crystalline lattices, illustrated by a linear chain of defect masses. The theoretical approach using the matching procedure for calculating phonon scattering at their domain boundaries is also presented. The reflection and transmission probabilities in the scattering region are calculated and illustrated for heavy and light defect masses. The conductance properties, in full accordance with the Landauer–Büttiker description of electron transport, are also calculated in these two cases. It is shown that the influence of defect masses can be explained by the strong decreases of conductance values caused by the asymmetric Fano resonance type. The realistic example presented here is instructive and may constitute a precursor model for analyzing the scattering of vibrational waves by an isolated defect in the two-dimensional crystalline lattice formed by atoms adsorbed on the surface of crystal substrates such as physisorbed noble gas films on close-packed atomic planes of the metal surface. A detailed discussion on the vibrational waves in the scattering region is given.
CHARACTERIZATION OF COADSORBED MOLECULAR SPECIES IN A MULTILAYER SOLVENT ENVIRONMENT ON INSULATING SURFACES
Authors: GÜNSTER J. , KRISCHOK S. , KEMPTER V. , STULTZ J. , GOODMAN D. W.
Published: October 2002

By employing metastable impact electron spectroscopy (MIES) and ultraviolet photoelectron spectroscopy (UPS, HeI) together with work function measurements and temperature-programmed desorption (TPD), the condensation of multilayer solvent systems, such as water and methanol on ultrathin Mo(100)-supported MgO films, has been investigated. In a first step, the techniques MIES/UPS and TPD are used to characterize the condensation of the pure solvent systems. Data collected in a coverage regime from submono- to multilayers at substrate temperatures between 100 and 500 K are surveyed in order to provide information about the buildup of the multilayer systems on an atomic level. Besides investigating the chemistry of pure phases, the present work provides insight into the chemistry of coadsorbed molecular species in a multilayer solvent environment. It is shown that thin films of amorphous water prepared at 100 K are a good candidate for studying aqueous multilayer chemistry under well-defined conditions, i.e. ultrahigh vacuum, by MIES. We are taking advantage of the unique properties of amorphous water films for investigating the interaction of water with coadsorbates, such as sodium and methanol. A deliberately chosen surface preparation technique in combination with the surface-sensitive electron-spectroscopic technique MIES enables the discrimination of various stages in the complex coadsorbate multilayer solvent reaction. Sodium has been chosen as a representative of a class of highly reactive and readily soluble species, and methanol as a surfactant.
DECOMPOSITION OF SiH4 ON THE SA TYPE STEPPED Si(100) SURFACE
Authors: KATIRCIOĞlu ŞENAY , ERKOÇ ŞAKIR
Published: October 2002

The density functional theory method is used to explore the mechanism of dissociative adsorption of silane (SiH4) on the SA type stepped Si(100) surface. Two reaction paths are described that produce silyl (SiH3) and hydrogen atom fragments adsorbed on the dimer bonds present on each terrace. It has been found that the initial stage of the dissociation of SiH4 on the SA type stepped Si(100) surface shows similarity to the dissociation of SiH4 on the flat Si(100) surface; SiH3 and hydrogen fragments bond to the Si dimer atoms by following the first reaction path.
THE SURFACE BAND STRUCTURE OF Li/Be$(10\bar{1}0)$
Authors: JOHANSSON L. I. , BALASUBRAMANIAN T. , VIROJANADARA C.
Published: October 2002

A photoemision study of the surface states on Be[Formula: see text] after Li adsorption at room temperature is reported. The surface band structure was mapped along four high symmetry directions of the SBZ. Fairly large shifts in the surface band locations were obtained but all surface states observed experimentally after Li adsorption were found to correspond to Be-derived states and no Li-derived surface states could be identified. The surface state bands located close to the Fermi level (E F ) were found to be affected the most and it is suggested that one surface state band which on the clean surface is located above E F is pulled down below E F after Li adsorption.
ITERATIVE IMAGE RECOVERY IN HOLOGRAPHIC LEED
Authors: SEUBERT A. , HEINZ K.
Published: October 2002

We report that the quality of atomic images reconstructed directly within the framework of holographic low energy electron diffraction can suffer from considerable atomic displacements. These are due to serious disturbances of the holographic object wave which exist when the object owns the same translational symmetry as the arrangement of beam splitters, for example when the latter induce a substrate reconstruction. We propose and test an iterative procedure for reducing these disturbances by a hybrid combination of the holographic reconstruction and some data fitting procedure. A reliable atomic image results after only a few iteration steps.
CRITICAL EXPONENT MEASUREMENT OF POOR QUALITY DIAMOND FILMS
Authors: SALVADORI M. C. , MELO L. L. , MARTINS D. R. , VAZ A. R. , CATTANI M.
Published: October 2002

We have synthesized poor quality diamond films, using high methane concentretion, by plasma-assisted chemical vapor deposition on silicon substrates. The roughness and dynamic critical exponents, α and β, of these films have been measured using an atomic force microscope. We show that the morphology, the roughness and the critical exponents of the diamond films are significantly different from those obtained with a low methane concentration. Our results are compared with Kardar–Parisi–Zhang theoretical predictions.
Supermarket Cyber Storm: Where adMart Went Wrong
Authors: Tai Susan
Published: October 2002

The launch of adMart, which sold and delivered discounted groceries, home appliances and office supplies through the Internet, fax and phone-in orders with free delivery service, provoked a wave of price-cutting by rival supermarket chains in June 1999. It forced Park'N Shop and Wellcome, the duopoly in the Hong Kong grocery market, to improve their services by providing free delivery services and expand their on-line business. However, the price war – although beneficial to consumers – proved to be a costly exercise for retailers. This case focuses on the impact on the grocery industry caused by adMart and how the present duopoly can bar the entry of new players. The causes of adMart's failure and Hong Kong's consumer attitudes toward grocery shopping on the Internet are also addressed.
Cycle and Carriage vs. Parallel Importers of Mercedes Benz Cars
Authors: Lee Khai Sheang , Lim Gaik Eng
Published: October 2002

Cycle and Carriage (C&C) was a leading distributor of motor vehicles in Singapore. So successful had its efforts been in developing the market for its flagship brand of Mercedes Benz cars that parallel importers entered the market to compete for a slice of the pie. C&C had tried to counter the parallel importers through various means such as negative advertising, withdrawal of warranty services and discrimination against Mercedes that were not purchased from the company in the provision of maintenance services, but all to no avail. To worsen matters, DaimlerChrysler withdrew the exclusive distributorship status of C&C with effect from 1 January 2001, leaving the company with a distribution right that is restricted to retailing only.
DOES FORMALIN-FIXATION ALTER THE EXTENT OF COLLAGEN AND ELASTIN CROSSLINKS IN HUMAN SPINAL INTERVERTEBRAL DISCS AND LIGAMENTUM FLAVA?
Authors: Tan Celia I. C. , Dunn Sonia , Kent G. Neil , Randall Andrew G. , Edmondston Stephen J. , Singer Kevin P.
Published: October 2002

The effect of formalin-fixation on the extent of collagen and elastin crosslinks in the matrix of human spinal intervertebral discs and ligamentum flava tissues was evaluated. Fresh discs (n = 5) and ligamentum flava (n = 22) were harvested and separated into two samples. One sample was stored in 10% buffered formalin and the other control sample in a freezer at -20°C. Using HPLC the paired anular (n = 72), nuclear (n = 22) and liagmentum flavum (n = 58) samples were dried, hydrolyzed and assayed for collagen and elastin crosslinks over a 25-week period.

There were no significant differences in the collagen, isodesmosine and desmosine content, and the extent of pyridinoline and deoxypyridinoline crosslinks, between fresh and formalin-fixed disc and ligament samples after 25 weeks of formalin fixation.

Short-term formalin-fixation does not significantly influence the collagen and elastin crosslink content or the extent of insoluble collagen crosslinks in spinal disc and ligamentum flavum tissues.
INTRAMEDULLARY ABSCESS OF THE SPINAL CORD
Authors: Acar Osman , Güney Önder , Kocaoğullar Yalçin
Published: October 2002

We report a rare case of intramedullary spinal cord abscess. The patient was operated on by surgical drainage and appropriate antibiotic therapy. Improvement was seen postoperatively. Significant changes in the presentation, management, and outcome in these more recent cases are emphasized.
EMG ANALYSIS OF TWO PORTIONS OF THE VASTUS MEDIALIS MUSCLE DURING SELECTED KNEE REHABILITATION EXERCISES
Authors: Hubbard John K. , Opersteny Steven
Published: October 2002

Despite a prevalence of literature describing the function and rehabilitation of the vastus medialis oblique (VMO) muscle, no literature exists which substantiates the existence of the VMO as a separate muscle entity from the vastus medialis longus (VML) muscle. The purpose of this study was to determine if the VMO and VML muscles exhibit any differences in muscle activity during performance of commonly performed knee rehabilitation exercises. Electromyographic (EMG) action potential amplitude from both the VMO and VML of normal adults were obtained simultaneously via indwelling electrodes during performance of ten different knee rehabilitation exercises. A two-way repeated measures analysis of variance was performed with the two portions of the vastus medialis (VM) muscle as one independent variable, the knee exercises as the second independent variable, and percent maximal voluntary contraction (%MVC) data as the dependent variable. Data was analyzed to determine whether any differences existed between the VMO and VML during performance of any of the selected exercises. Analysis of the data revealed that although significant differences existed in %MVC's generated between exercises, no differences were seen between the VMO and VML during any of the individual exercises or the group of exercises as a whole. Exercises utilized to strengthen one portion of the VM muscle will simultaneously strengthen the other portion. These findings show that no functional differences exist between the VMO and VML, and lessen the credibility of the theory that they are separate muscle entities.
The Quality of Financial Infrastructure and Financial Resilience: Contrasting Taiwan and Thailand
Authors: Peter Gray H.
Published: October 2002

The experiences of Taiwan and Thailand following the 1997 crisis of the baht provide evidence of the importance of the quality of the financial infrastructure of a country in its ability to deal with unstable financial markets. The very high quality of the financial infrastructure in Taiwan (together with its peripheral role in the crisis itself) enabled its economy to escape relatively unscathed. In contrast, a lack of sophisticated financial institutions and nonfinancial firms both triggered the crisis in Thailand and required the Thai economy to experience its full force.
A Comparison of Hedge Effectiveness and Price Discovery between TAIFEX TAIEX Index Futures and SGX MSCI Taiwan Index Futures
Authors: Chen Shen-Yuan , Lin Ching-Chung , Chou Pin-Huang , Hwang Dar-Yeh
Published: October 2002

This article uses daily data from July 21, 1998 to July 31, 2000 to examine the hedging effectiveness, price behavior, and lead-lag relationship of SGX MSCI Taiwan index futures and TAIFEX TAIEX futures. By applying the Bayesian approach using Gibbs sampler, we find that TAIFEX index futures has a better hedging performance. A variance ratio test reveals that mean reversion and negative correlation of returns exist in SGX index futures. Only TAIFEX TAIEX futures is cointegrated with TAIEX spot. The uni-directional Granger causality between the two futures markets and spot market are from SGX to TAIEX and from TAIEX to TAIFEX. In terms of price discovery, SGX MSCI Taiwan index futures play a more important role than TAIFEX TAIEX futures.
QUASI-ASSIGNMENT COOPERATIVE GAMES
Authors: AURIOL I. , MARCHI E.
Published: October 2002

The relevant assignments games were generalized to k-sided assignment games recently by Quint and they are related to permutation games. If in the definition of assignment games, some inequalities are converted into equalities, and the remaining inequalities are preserved as such, one obtain the quasi-assignment games. We study here their characterization and we extend them to k-sided quasi assigment cooperative games.
BOUNDEDNESS OF THE EXTREMAL SOLUTION FOR SEMILINEAR ELLIPTIC PROBLEMS
Authors: YE DONG , ZHOU FENG
Published: October 2002

We investigate here the boundedness of extremal solutions for some semilinear elliptic equation -Δu=λf(u) posed on a bounded smooth domain of ℝN with Dirichlet boundary condition. Some sufficient conditions for f are established to ensure the regularity of extremal solutions when N ≤ 9, which cover all well-known cases.
A MEAN CONTINUITY TYPE RESULT FOR CERTAIN SOBOLEV SPACES WITH VARIABLE EXPONENT
Authors: FIORENZA ALBERTO
Published: October 2002

For functions f in Sobolev spaces W1,p(x)(Ω) with exponent lower semicontinuous, bounded away from 1 and ∞ and with the property of the density of smooth functions, it is shown that for each open set ω ⊂⊂ Ω, for each h ∈ RN such that ω+th ⊂ Ω ∀ t∈ [0,1], the following inequality holds [Formula: see text] where min p(x, x + h) denotes the minimum of p along the segment whose endpoints are x, x + h. As a consequence, if p(x) is also continuous, for mollifiers (ρn){n ∈ N the liminf and the limsup of [Formula: see text] are respectively minorized and majorized by expressions equivalent to ‖|∇f|‖Lp(x)(Ω).
TETRACOMPOSITION
Authors: KLUGE LIIVI , PAAL EUGEN
Published: October 2002

We consider basic algebraic constructions associated with an abstract pre-opered, such as a ⌣-algebra, total composition •, pre-coboundary operator δ tribraces {·, ·, ·} and tetrabraces {·, ·, ·, ·}. By using the Gerstenhaber method, a derivation of the precoboundary operator over the tetrabraces is calculated in terms of the ⌣- multiplication and tribraces.
MECHANICAL PROPERTIES OF DISEASED HEARTS DURING ADAPTATION
Authors: CHAUDHRY HANS R. , BUKIET BRUCE , RITTER ARTHUR B. , ARORA ROHIT
Published: October 2002

In this paper, a method is developed to determine the material constants of normal and diseased human hearts in vivo. With these material constants, one can compute regional stresses and strains through the left ventricular (LV) wall. This knowledge provides a better understanding of the heart adaptation process and may lead to earlier diagnosis of heart disease. It also may enable earlier treatment of heart disease, and evaluation of the efficacy of treatments for it.

The heart is modeled as a thick cylindrical shell and large deformation theory, incorporating residual stresses is employed to compute the regional stresses and strains through the LV wall. These stresses and strains at the end diastolic state for the normal, hypertensive and congestive heart failure cases are presented. The average circumferential stress is also computed at the end systolic state for these cases.
POLICY-AGENTS FOR NEGOTIATION WITHIN VIRTUAL ORGANIZATIONS
Authors: CZAP HANS
Published: October 2002

Real and virtual organizations are conducted by preferences, goals, and policies. Since virtual organizations have a two-level structure the preferences of these different levels are a source of conflicting interests. Also, management policies itself are subject to change, especially in a virtual setting. Therefore, agility has superior value, causing the need to develop business information and planning systems that may be adapted easily. Both mentioned aspects of business planning software, namely, ease adaptation on one side and the integration of individual preferences and goals on the other are treated in the paper. An architectural design is proposed that meets the needs of virtual organizations as far as any conflicts can be solved on an individual basis. This concept is further elaborated. Negotiating agents that obey the preferences of their principals are considered as a means to search for compromise solutions. An extensive example derived from hospital management illustrates the concept.
MARKOV DECISION APPROACH FOR TIME-CONSTRAINED TRADING IN ELECTRONIC MARKETPLACE
Authors: CHOI SAMUEL P. M. , LIU JIMING
Published: October 2002

The recent advent in Internet technology has made electronic trading increasingly popular. Nevertheless, existing electronic trading systems still heavily rely on human decision making. In order to facilitate the new trading environment, one of the main trends is to employ autonomous agents as representatives of human buyers and sellers. In particular, given a user requirement and an imposed deadline, an autonomous agent has to search for possible deals from an electronic marketplace on behalf of its owner. One problem such an agent must face is: given a collection of offers and the remaining time, should I accept the current best offer, or continue to search for a better one, at a risk of losing the current offers? Similar time-constrained trading problems have been studied long time ago by the Markov decision process community. This paper alters the formulation by adopting assumptions suitable for electronic trading environments, and then derive the optimal trading strategy in terms of the agent's expected utility. Three optimization methods are proposed in order to reduce the infinite state space into the one with a manageable size. Experimental results verify the effectiveness of the methods for practical use.
STRUCTURAL FEATURE OF AChE INHIBITOR HUPERZINE B IN NATURE AND IN THE BINDING SITE OF AChE: DENSITY FUNCTIONAL THEORY STUDY COMBINED WITH IR DETERMINATION
Authors: LUO XIAOMIN , FENG CHENG , TAN XIAO-JIAN , TAN CHANGHENG , ZHU DAYUAN , SHEN JIANHUA , HUANG XIAOQIN , LIU TONG , CHEN KAIXIAN , JIANG HUALIANG , ZHU WEILIANG , PUAH CHUM MOK , DVIR HAY , HAREL MICHAL , SUSSMAN JOEL L. , SILMAN ISRAEL
Published: October 2002

Quantum chemical DFT-B3LYP/6-31G* method and IR spectrometry have been used to investigate the natural and binding structures of Huperzine B (HupB) in order to better understand the interaction nature between acetylcholinesterase (AChE) and its inhibitor, with the view of designing new AChE inhibitors. The predicted and experimental results reveal that both the natural state and binding form of HupB adopt the chair conformation. Furthermore, the B3LYP/6-31G* results suggest that structure S1 should be the dominant form of the two possible chair structures (S1 and S2, Fig. 2). The calculated results also show that the condensed ring structure composing of rings A, B and C is very rigid. Therefore, its flexibility does not need to be considered when we try to dock this structure to its target. Indeed, this supposition is confirmed by the excellent alignment of the binding structure produced from our recent/break X-ray crystallographic structure of the HupB-AChE complex with the B3LYP/6-31G* predicted geometry. Among all the 111 predicted vibrational bands, the mode 110, which is resulted from the stretching of the bond N2–H and having the second highest frequency, is essential for the geometrical identification. The difference between our predicted strongest absorption band and experimental IR spectrum suggests that a strong intermolecular interaction, which could be a hydrogen bond, exists in HupB crystal. The electrostatic potential surface of HupB derived from our B3LYP/6-31G* CHelpG atomic charge suggests a mechanism of how HupB would interact with its target. In addition, the good agreement between predicted vibrational bands (scaled by a factor of 0.96) and experimental result shows that B3LYP/6-31G* is a good tool for studying such kind of natural compound.
REACTION RATES: ACCURATE QUANTUM DYNAMICAL CALCULATIONS FOR POLYATOMIC SYSTEMS
Authors: MANTHE UWE
Published: October 2002

Rate constants of chemical reactions can be computed directly: employing flux correlation functions, no scattering calculations are required. If the reaction is direct, the dynamical simulation can be restricted to the vicinity of the reaction barrier. Therefore accurate thermal rate constants and cumulative reaction probabilities can be calculated for rather large systems. Recent calculations have studied systems with up to six atoms, e.g., H + CH 4 → H 2 + CH 3. The calculations provide a full-dimensional quantum description of the reaction process.

In the article, an introduction to the theory of flux correlation functions is given. Methods for the efficient computation of accurate thermal rate constants and cumulative reaction probabilities are reviewed. Connections to transition state ideas are highlighted. The multi-configurational time-dependent Hartree (MCTDH) approach, which facilitates efficient multi-dimensional wave packet propagation, is described and its use in reaction rate calculation is discussed. As examples, recent results for the prototypical polyatomic reaction H + CH 4 → H 2 + CH 3 are presented and rotational effects on the reaction rates of H 2 + OH → H + H 2 O , O + HCl → OH + Cl , and H 2 + Cl → H + HCl are discussed.
COMPUTATION OF MULTICENTER NUCLEAR-ATTRACTION INTEGRALS OF INTEGER AND NONINTEGER n SLATER ORBITALS USING AUXILIARY FUNCTIONS
Authors: GUSEINOV I. I. , MAMEDOV B. A.
Published: October 2002

A unified treatment of multicenter nuclear-attraction integrals with integer n and noninteger n* Slater-type orbitals (ISTOs and NISTOs) is described. Using different sets of series expansion formulas for NISTOs and their two-center distributions in terms of ISTOs at a displaced center obtained by one of the authors, the three-center nuclear-attraction integrals over NISTOs are expressed through the products of overlap and two-center nuclear-attraction integrals. The two-center overlap and nuclear-attraction integrals are calculated by the use of well-known auxiliary functions Aσ and Bk. Accuracy of the computer results is quite high for quantum numbers, screening constants, and location of orbitals.
TOWARD THE MECHANISM OF LONG-RANGE CHARGE TRANSFER IN DNA: THEORIES AND MODELS
Authors: YAN YI JING , ZHANG HOUYU
Published: October 2002

This article reviews our recent theoretical development toward understanding the interplay of electronic structure and dephasing effects on charge transfer/transport through molecular donor-bridge-acceptor systems. Both the generalized scattering matrix and Green's function formalisms for partially incoherent tunneling processes are summarized. Presented is also an exact mapping between the kinetic rate constants and the electric conductances in evaluation of chemical yields of sequential charge transfer in the presence of competing branching reactions. As an important example, the mechanism of long-range charge transfer in DNA in aqueous solution is investigated with a quantum chemistry implementation of the generalized Green's function formalism. A time scale of about 5 ps is found for the partially incoherent tunneling through a thymine/adenine π-stack in DNA. Numerical results further show that while the carrier oxidative charge does hop sequentially over all guanine sites in a DNA duplex, its tunneling over thymine/adenine bridge base pairs deviates substantially from the superexchange regime. Presented are also evidences for the involvement of both intrastrand and interstrand pathways in the ground state hole charge transfer in DNA.
Optical Performance of Liquid Crystal Cells with Asymmetric Slit-Patterned Electrodes in Various Applied Field Configurations
Authors: He Zhan , Toshiaki Nose Toshiaki Nose , Susumu Sato Susumu Sato
Published: October 2002

The performance of liquid crystal (LC) cells with asymmetric slit-patterned electrode structures in various applied field configurations is studied in detail, by measuring the interference fringe patterns and simulating the two-dimensional director distributions of liquid crystal by a finite element method (FEM). We investigate the molecular orientation effects in inhomogeneous electric fields and the optical properties of these cells as cylindrical microlenses, and show that disclinations, which deteriorate the lens properties, can be eliminated by adopting an appropriate applied field configuration.
Arsenic Pressure Dependence of Surface Diffusion of Ga on Nonplanar GaAs Substrates
Authors: Shen Xu-Qiang , Daisuke Kishimoto Daisuke Kishimoto , Tatau Nishinaga Tatau Nishinaga
Published: October 2002

The arsenic pressure dependence of Ga adatom surface diffusion in molecular beam epitaxy (MBE) on nonplanar substrates was investigated. By using in situ scanning microprobe reflection high-energy electron diffraction (µ-RHEED), the distribution of the growth rate of GaAs on the (001) surface near the edge of the (111)A or (111)B sidewall was measured under various arsenic pressures. The surface diffusion length of Ga adatom incorporation on the (001) surface derived from the distribution is on the order of micrometers and it shows a strong dependence on arsenic pressure. A simple model based on one-dimensional surface diffusion was proposed. With this theory, the lifetime of Ga adatom incorporation on other surfaces is obtained.
Copper Precipitation at the Silicon-Silicon-Dioxide Interface: Role of Oxygen
Authors: Correia Antonio , Maurice Dominique Ballutaud
Published: October 2002

Copper contamination is often the origin of the lifetime degradation during processing of solar cells. Its behaviour during oxidation is investigated in this paper. It is shown by analytical transmission electron microscopy that the thermal oxidation of Czochralski silicon induces at the silicon-silicon-dioxide interface the precipitation of large copper colonies associated with oxidation-stacking-fault (OSF) Frank partial dislocations decorated with oxygen. The precipitation process is different in float-zone silicon where the Frank partial dislocations bounding the OSFs are themselves nucleation sites for copper precipitates.
Rapid Thermal Annealing Technique for Polycrystalline Silicon Thin-Film Transistors
Authors: Ichio Yudasaka Ichio Yudasaka , Hiroyuki Ohshima Hiroyuki Ohshima
Published: October 2002

The fundamental characteristics of a rapid thermal annealing (RTA) technique that has been applied to polycrystalline silicon thin-film transistors (poly-Si TFTs) have been investigated and short channel (less than 3 µ m) poly-Si TFTs have been achieved. The annealing characteristics of a thin silicon film on a transmissive substrate are entirely different from those of a silicon wafer. An arc lamp is essential as the RTA light source. A self-controlled effect in activation annealing was observed. Size and pattern density of silicon islands affect the uniformity of annealing. An absorption layer of a silicon film makes the use of RTA practical. A shift-register circuit composed of short channel TFTs was also evaluated.
Influence of Humidity on AC Electrical Breakdown in Plasma-Polymerized Thin Films
Authors: Keiichi Miyairi Keiichi Miyairi
Published: October 2002

The ac electrical breakdown has been measured in plasma-polymerized thin films. The breakdown strength is on the order of 8–10 MV/cm under a dry condition; however, it decreases drastically with humidity. Leakage current increases with humidity, while dielectric loss does not show significant increase with it. Results have been explained in terms of thermal breakdown based on Joule heating due to an enhanced leakage current through a localized narrow channel.
Effect of Si Interlayers on Stress and Curvature Radius of GaAs/Si and GaAs/Si/GaAs/Si Heterostructures with Interfacial Misfit Dislocations
Authors: Kazuo Nakajima Kazuo Nakajima , Kimiko Furuya Kimiko Furuya
Published: October 2002

A theoretical model is proposed to calculate the stress distribution in multilayer heterostructures perturbed by introduction of interfacial misfit dislocations and thermal stress. In this model, the stress relaxation effect caused by interfacial misfit dislocations is considered to spread all over the layers above the heterointerface. Using this model, the stress and curvature radius at 25° C are calculated for the GaAs/Si and GaAs/Si/GaAs/Si heterostructures with interfacial misfit dislocations. The stress shared in the GaAs layer becomes smaller when Si interlayers are inserted into the GaAs layer of the GaAs/Si heterostructure. The curvature radius of the GaAs/Si/GaAs/Si (GaAs/Si with Si interlayers) heterostructure increases as the thickness of the Si interlayer increases. The GaAs/Si heterostructure becomes flat more easily upon insertion of Si interlayers into the GaAs layer.
Lead-Strontium-Telluride Films and Lasers Prepared by Hot-Wall Epitaxy
Authors: Sakurai Nobuhiro , Hiroshi Fujiyasu Hiroshi Fujiyasu , Akihiro Ishida Akihiro Ishida
Published: October 2002

Pb1-
x

Sr

x

Te films were prepared by hot-wall epitaxy on BaF2(111) substrates. X-ray diffraction analysis, optical transmission measurement, Hall measurement and electron-probe micro-analysis (EPMA) were performed for the films. It was observed that the increasing rate of the lattice constant of the Pb1-
x

Sr

x

Te films with the SrTe content was considerably larger than that estimated from Vegard's law. Pb1-
x

Sr

x

Te/PbTe double-heterostructure (DH) and multiple-quantum-well (MQW) lasers were also prepared for the first time by hot-wall epitaxy. Pulsed laser operations were obtained up to 227 K (4.1 µ m) for the DH laser and up to 220 K (3.5 µ m) for the MQW laser. Large output energy shifts due to misfit strain in the active layer were observed.
Behaviors of Hydrogen and Oxygen on Claned Silicon Surfaces
Authors: Kazuyuki Ueda Kazuyuki Ueda
Published: October 2002

Silicon surfaces of CZ-grown wafer have been investigated by time-of-flight type electron-stimulated desorption spectroscopy (TOF-ESD). Though such surfaces had been believed to be clean enough after heating and flashing in UHV, considerable amounts of hydrogen and oxygen ions were detected by TOF-ESD on these surfaces. The yield of ESD oxygen ions decreased during cooling of the specimen to liquid nitrogen temperature after heating. The proton yield increased normally during cooling after flashing because of hydrogen diffusion from the bulk. Total cross sections of proton and oxygen ions for slow electron irradiation are estimated to be on the order of 10-19 cm2.