bluuebunny/crossref_metadata_2025 huggingface dataset:
Defect sites at the (001) surface of mordenite: An ab initio study
Authors: Bučko T. , Benco L. , Hafner J.
Published: April 2003

The mechanisms and energetics of the formation of various defects upon dehydration of the surface of pure-siliceous and Al-monosubstituted mordenite are investigated using a periodic ab initio density functional theory technique. An energetically favorable defect at the pure-siliceous surface is a strained two-membered Si–O ring (2MR) formed via elimination of a water molecule from a pair of neighboring terminal silanol groups. Assuming the formation of two-membered rings, the dehydration-energy of the (001) surface of pure-silica mordenite is 133 kJ/mol. A relatively high reaction barrier of 179 kJ/mol coincides with the experimental observation that these defects are formed at high temperatures >700 K. Despite a short Si–Si distance of 2.35 Å across the 2MR which is comparable to the bond length between Si atoms in silicon in diamond structure, the electron-localization function reveals no bonding interaction between Si atoms on the 2MR. In the Al-substituted surfaces, the dehydration proceeds via proton transfer from the Brønsted-acid site (BA) to a neighboring terminal hydroxyl group. The low values of two subsequent energetic barriers of dehydration of 13 and 10 kJ/mol suggest that the surface BA sites are likely to be destroyed at even modest temperatures. The most stable defects formed in this mechanism are ones containing a threefold-coordinated Al atom and a defect with both an Al atom and a bridging OH group located on a two-membered ring. The heat of reaction of only 9 kJ/mol and the activation energy of the transformation between these two configurations of 26 kJ/mol suggest that both defects occur with similar probability.
Path-integral Monte Carlo calculation of reaction-diffusion equation
Authors: Ando Koji , Sumi Hitoshi
Published: April 2003

Path-integral formulation and Monte Carlo calculations of the reaction-diffusion equation of condensed phase chemical reactions are presented. Numerical calculations are demonstrated for the Sumi–Marcus model of electron transfer reactions, which include the slow and intermediate diffusion regimes, ultrafast photoinduced electron transfers, and nonequilibrium initial distributions.
Equilibrium molecular dynamics simulations of the transport coefficients of the Yukawa one component plasma
Authors: Salin Gwenaël , Caillol Jean-Michel
Published: April 2003

Equilibrium molecular-dynamics simulations in the microcanonical ensemble have been performed to obtain the thermal conductivity and the two viscosities of the Yukawa one-component plasma from the Kubo formulas. The expressions of the Kubo currents (pressure tensor and energy current) which enter these formulas are derived in terms of Ewald sums. The simulation results for the transport coefficients are compared with the predictions of the Chapman–Enskog theory which has been solved numerically.
Decay of trapped-particle asymmetry modes in non-neutral plasmas in a Malmberg–Penning trap
Authors: Mason Grant W.
Published: April 2003

The mechanism for the strong damping of diocotron-like azimuthal trapped-particle asymmetry modes in a Malmberg–Penning trap is investigated with a detailed three-dimensional particle-in-cell computer simulation. The m=1,kz≠0 modes are created by a voltage squeeze from a mid-detector ring followed by a displacement of trapped particles in opposite directions on either side of the ring. The voltage squeeze creates a population of particles confined to half the trap length (trapped) and a population of particles that move longitudinally along the full length of the cylinder (untrapped). The damping of the modes is found to be the result of radial transport relative to the m=1 mode (charge) center caused by transitions of particles from untrapped-to-trapped states induced by diffusion of the particles in velocity space. The transport is the immediate consequence of a difference in dynamical orbits for trapped and untrapped particles. The random walk in velocity space results in particles repeatedly changing state from trapped to untrapped and back. The dependence of the mode frequency and the exponential decay constant are explored as a function of squeeze voltage, magnetic field, and temperature in order to establish scaling behavior.
Discovery of a significant, nontopological preference for antiparallel alignment of helices with parallel regions in sheets
Authors: Hespenheide Brandon M. , Kuhn Leslie A.
Published: April 2003

To help elucidate the role of secondary structure packing preferences in protein folding, here we present an analysis of the packing geometry observed between α‐helices and between α‐helices and β‐sheets in 1316 diverse, nonredundant protein structures. Finite‐length vectors were fit to the α‐carbon atoms in each of the helices and strands, and the packing angle between the vectors, Ω, was determined at the closest point of approach within each helix–helix or helix–sheet pair. Helix–sheet interactions were found in 391 of the proteins, and the distributions of Ω values were calculated for all the helix–sheet and helix–helix interactions. The packing angle preferences for helix–helix interactions are similar to those previously observed. However, analysis of helix–strand packing preferences uncovered a remarkable tendency for helices to align antiparallel to parallel regions of β‐sheets, independent of the topological constraints or prevalence of β‐α‐β motifs in the proteins. This packing angle preference is significantly diminished in helix interactions involving mixed and antiparallel β‐sheets, suggesting a role for helix–sheet dipole alignment in guiding supersecondary structure formation in protein folding. This knowledge of preferred packing angles can be used to guide the engineering of stable protein modules.
Solution structure of the N‐terminal amphitropic domain of Escherichia coli glucose‐specific enzyme IIA in membrane‐mimetic micelles
Authors: Wang Guangshun , Keifer Paul A. , Peterkofsky Alan
Published: April 2003

The N‐terminal domain of enzyme IIAGlc of the Escherichia coli phosphoenolpyruvate:sugar phosphotransferase system confers amphitropism to the protein, allowing IIAGlc to shuttle between the cytoplasm and the membrane. To further understand this amphitropic protein, we have elucidated, by NMR spectroscopy, the solution structure of a synthetic peptide corresponding to the N‐terminal domain of IIAGlc. In water, this peptide is predominantly disordered, consistent with previous data obtained in the absence of membranes. In detergent micelles of dihexanoylphosphatidylglycerol (DHPG) or sodium dodecylsulfate (SDS), however, residues Phe 3–Val 10 of the peptide adopt a helical conformation in the ensemble of structures calculated on the basis of NOE‐derived distance restraints. The root mean square deviations for superimposing the backbone atoms of the helical region are 0.18 Å in DHPG and 0.22 Å in SDS. The structure, chemical shifts, and spin–spin coupling constants all indicate that, of the four lysines in the N‐terminal domain of IIAGlc, only Lys 5 and Lys 7 in the amphipathic helical region interact with DHPG. In addition, the peptide‐detergent interactions were investigated using intermolecular NOESY experiments. The aliphatic chains of anionic detergents DHPG, SDS, and 2,2‐dimethyl‐2‐silapentane‐5‐sulfonate sodium salt (DSS) all showed intermolecular NOE cross‐peaks to the peptide, providing direct evidence for the putative membrane anchor of IIAGlc in binding to the membrane‐mimicking micelles.
Aerodynamics of a Transonic Centrifugal Compressor Impeller
Authors: Ibaraki Seiichi , Matsuo Tetsuya , Kuma Hiroshi , Sumida Kunio , Suita Toru
Published: April 2003

High-pressure ratio centrifugal compressors are applied to turbochargers and turboshaft engines because of their small dimensions, high efficiency, and wide operating range. Such a high-pressure ratio centrifugal compressor has a transonic inlet condition accompanied with a shock wave in the inducer portion. It is generally said that extra losses are generated by interaction of the shock wave and the boundary layers on the blade surface. To improve the performance of high-pressure ratio centrifugal compressor, it is necessary to understand the flow phenomena. Although some research works on transonic impeller flow have been published, some unknown flow physics are still remaining. The authors designed a transonic impeller, with an inlet Mach number about 1.3, and conducted detailed flow measurements by using laser doppler velocimetry (LDV). In the result, the interaction between the shock wave and tip leakage vortex at the inducer and flow distortion at the downstream of inducer were observed. The interaction of the boundary layer and the shock wave was not observed. Also, computational flow analysis was conducted and compared with experimental results.
A User's Guide to Life
Authors: Emery Nathan J.
Published: April 2003

Liars, Lovers, and Heroes
What the New Brain Science Reveals About How We Become Who We Are. Steven R. Quartz and Terrence J. Sejnowski. William Morrow, New York, 2002. 352 pp. $26.95, C$41.50. ISBN 0-688-16218-5.

Written for a popular audience, the book argues that our humanity is determined by a dynamic engagement between the brain and the surrounding world. The authors describe a reiterated process through which "engagement with the world excites brain chemistry, which drives further engagement, which encourages the development of cultural complexity."
Cytostatic 6-Arylpurine Nucleosides V. Synthesis of 8-Substituted 6-Phenylpurine Ribonucleosides
Authors: Hocek Michal , Hocková Dana , Štambaský Jan
Published: April 2003

Regioselective Suzuki-Miyaura reaction of 8-bromo-6-iodo-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)purine with phenylboronic acid gave 8-bromo-6-phenylpurine derivative that was used for cross-coupling reactions (with PhB(OH)2, Me3Al, Et3Al, BnZnCl) or nucleophilic substitutions (with NaOH, NaOMe, NH3, NHMe2 or thiourea). A series of 8-X-substituted 6-phenyl-9-(β-D-ribofuranosyl)purines (X = Ph, Me, Et, Bn, OH, OMe, NH2, NMe2, SH) was prepared in this way directly or after deprotection. None of the title nucleosides exhibited any considerable cytostatic activity.
Synthesis of Helicene Scaffolds via [2+2+2] Cycloisomerization of Aromatic Triynes
Authors: Stará Irena G. , Starý Ivo , Kollárovič Adrian , Teplý Filip , Šaman David , Fiedler Pavel
Published: April 2003

Triynes R-C≡C-CH2CH2-Ar-C≡C-Ar'-CH2CH2-C≡C-R were subjected to Co(I)- or Ni(0)-mediated intramolecular [2+2+2] cycloisomerization to provide corresponding tetrahydropentahelicene, tetrahydrohexahelicene, and tetrahydroheptahelicene in good to moderate yields. The reaction tolerates various substituents at pendant acetylene moieties (R = H, CH3, trimethylsilyl, not triisopropylsilyl) and fluorine in an aromatic part. By contrast, under Rh(I) or Pd(0) catalysis, triyne with the CH2OCH2 tether lost pendant propargyl moieties and an aromatic spiroketal was formed preferentially.
EXPERIMENTS WITH PROGRAM PARALLELIZATION USING ARCHETYPES AND STEPWISE REFINEMENT
Authors: MASSINGILL BERNA L
Published: April 2003

Parallel programming continues to be difficult and error-prone, whether starting from specifications or from an existing sequential program. This paper presents (1) a methodology for parallelizing sequential applications and (2) experiments in applying the methodology. The methodology is based on the use of stepwise refinement together with what we call parallel programming archetypes (briefly, abstractions that capture common features of classes of programs), in which most of the work of parallelization is done using familiar sequential tools and techniques, and those parts of the process that cannot be addressed with sequential tools and techniques are addressed with formally-justified transformations. The experiments consist of applying the methodology to sequential application programs, and they provide evidence that the methodology produces correct and reasonably efficient programs at reasonable human-effort cost. Of particular interest is the fact that the aspect of the methodology that is most completely formally justified is the aspect that in practice was the most trouble-free.
PARALLEL ALGORITHMS FOR LONGEST INCREASING CHAINS IN THE PLANE AND RELATED PROBLEMS
Authors: ATALLAH MIKHAIL J. , CHEN DANNY Z. , KLENK KEVIN S.
Published: April 2003

Given a set [Formula: see text] of n points in the plane such that each point in [Formula: see text] is asscociated with a nonnegative weight, we consider the problem of computing the single-source longest increasing chains among the points in [Formula: see text] This problem is a generalization of the plannar maximal layers problem. In this paper, we present a parallel algorithm that computes the single-source longest incresing chains in the plane in [Formula: see text] time using [Formula: see text] processors in the CREW PRAM computational model. We also solve a related problem of computing the all-pairs longest paths in an n-node weighted planar st-graph, in [Formula: see text] time using [Formula: see text] CREW PRAM processors. Both of our parallel algorithms are improvement over the previously best known results.
PHASES OF THERMAL SUPER-YANG–MILLS
Authors: PARIKH MAULIK K.
Published: April 2003

We review the thermodynamics of the confined and unconfined phases of [Formula: see text] super-Yang–Mills at large N on a three-sphere, focusing especially on the confinement–deconfinement transition. We determine an N-dependent phase boundary and point out some directions for future work.
BLACK HOLE THERMODYNAMICS FROM THE POINT OF VIEW OF SUPERSTRING THEORY
Authors: AKHMEDOV E. T.
Published: April 2003

In this review we try to give a pedagogical introduction to the recent progress in the resolution of old problems of black hole thermodynamics within superstring theory. We start with a brief description of classical black hole dynamics. Then, follow with the consideration of general properties of supersymmetric black holes. We conclude with the review of the statistical explanation of the black hole entropy and string theory description of the black hole evaporation.
QUARK STRUCTURE OF PSEUDOSCALAR MESONS
Authors: FELDMANN THORSTEN
Published: April 2003

I review to which extent the properties of pseudoscalar mesons can be understood in terms of the underlying quark (and eventually gluon) structure. Special emphasis is put on the progress in our understanding of η–η′ mixing. Process-independent mixing parameters are defined, and relations between different bases and conventions are studied. Both, the low-energy description in the framework of chiral perturbation theory and the high-energy application in terms of light-cone wave functions for partonic Fock states, are considered. A thorough discussion of theoretical and phenomenological consequences of the mixing approach will be given. Finally, I will discuss mixing with other states (π0, ηc, …).
SINGLE SPIN ASYMMETRIES IN INCLUSIVE HIGH ENERGY HADRON–HADRON COLLISION PROCESSES
Authors: LIANG ZUO-TANG , BOROS C.
Published: April 2003

It has been realized for quite a long time that single-spin experiments, in which one of the colliding objects is transversely polarized, can be helpful in studying the properties of strong interaction in general and in testing quantum chromodynamics (QCD) in particular. Striking effects have been observed in the past few years which deviate drastically from the expectation of the perturbative QCD parton model. These effects have received much attention. New experiments of the similar type are underway and/or planned. Different theoretical attempts have been made to understand these effects. In this review, the special role played by singly polarized high-energy hadron–hadron collisions in high energy spin physics is emphasized. Characteristics of the available data for inclusive hadron productions are briefly summarized. Different theoretical approaches for such processes are reviewed with special attention to a nonperturbative model which explicitly takes the orbital motion of the valence quarks and hadronic surface effects into account. The connection between such asymmetries and hyperon polarization in unpolarized reactions is discussed. An example of the possible application of such experimental results in other processes is given.
SEMIRELATIVISTIC TREATMENT OF BOUND STATES
Authors: LUCHA WOLFGANG , SCHÖBERL FRANZ F.
Published: April 2003

This review discusses several aspects of the semirelativistic description of bound states by the spinless Salpeter equation (which represents the simplest equation of motion incorporating relativistic effects) and, in particular, presents or recalls some very simple and elementary methods which allow us to derive rigorous statements on the corresponding solutions, that is, on energy levels as well as wave functions.
PHYSICS OF W BOSONS AT LEP2
Authors: CAMPANELLI MARIO
Published: April 2003

After the first observations of W bosons in leptonic interactions, about 4000 WW candidate events per experiment have been collected at LEP2. This data allows the measurement of the WW production cross section at different center-of-mass energies, as well as W decay branching fractions. The W hadronic branching fraction can be converted into a test of the unitarity of the CKM matrix, or into an indirect determination of the matrix element |V cs |. A more direct measurement coming from charm tagging is also performed. The W mass has been measured via the cross section (in the threshold region) and the direct reconstruction of the W decay products, using different techniques to account for the distortions due to experimental effects. The main systematic error to the mass reconstruction in the fully hadronic channel comes from QCD effects like Color reconnections and Bose–Einstein correlations, extensively studied in WW events. In e+e- collisions W pairs can be produced in s-channel via a three-vector boson vertex, so a direct study of the trilinear gauge boson couplings is possible. Modification of WW cross section and distributions of W production and decay angles would be an indication of nonstandard couplings, thus a first hint for the presence of new physics.
CP VIOLATING ASYMMETRIES OF b QUARKS AND LEPTONS IN $e^+ e^-\to t\bar t$ AND SUPERSYMMETRY
Authors: CHRISTOVA EKATERINA
Published: April 2003

The distributions of the single decay b-quarks and leptons from [Formula: see text] assuming CP violation are reviewed. Different asymmetries, sensitive independently to CP violation in the production and in the decay, and sensitive to the real and imaginary parts of dγ and dZ are defined. The analytic expressions are general and independent on the model of CP violation. In most of them all phase space integrations are fulfilled analytically. Numerical results in the MSSM with complex couplings are presented.
RECOGNITION OF HAND-PRINTED LATIN CHARACTERS BASED ON GENERALIZED HOUGH TRANSFORM AND DECISION TREE LEARNING TECHNIQUES
Authors: AMIN ADNAN
Published: April 2003

This paper presents a new technique for the recognition of hand-printed Latin characters using machine learning. Conventional methods have relied on manually constructed dictionaries which are not only tedious to construct but also difficult to make tolerant to variation in writing styles. The advantages of machine learning are that it can generalize over a large degree of variation between writing styles, and recognition rules can be constructed by example.

Characters are scanned into the computer and preprocessing techniques transform the bit-map representation of the characters into a set of primitives which can be represented in an attribute base form. A set of such representations for each character is then input to C4.5 which produces a decision tree for classifying each character.
CHAOS COMMUNICATION OVER NOISY CHANNELS
Authors: HASLER MARTIN , SCHIMMING THOMAS
Published: April 2003

The problem of transmitting digital information using chaotic signals over a channel with Gaussian white noise perturbation is introduced rigorously. It is shown that discrete time base-band chaotic communication systems with discrete time Gaussian white noise in the channel are sufficiently general in this context. The optimal receiver is given explicitly in terms of conditional probabilities. For the example of chaos shift keying using iterations of the tent map, the optimal classifier is constructed explicitly. Finally, it is shown how previously published methods, in particular those based on chaos synchronization, fit into this framework.
CHARACTERISTICS OF THE SYNCHRONIZATION OF BRAIN ACTIVITY IMPOSED BY FINITE CONDUCTION VELOCITIES OF AXONS
Authors: FREEMAN WALTER J.
Published: April 2003

The electrical activity of neurons in brains fluctuates erratically both in terms of pulse trains of single neurons and the dendritic currents of populations of neurons. Obviously the neurons interact with one another in the production of intelligent behavior, so it is reasonable to expect to find evidence for varying degrees of synchronization of their pulse trains and dendritic currents in relation to behavior. However, synaptic communication between neurons depends on propagation of action potentials between neurons, often with appreciable distances between them, and the transmission delays are not compatible with synchronization in any simple way. Evidence is on hand showing that the principal form of synchrony is by establishment of a low degree of covariance among very large numbers of otherwise autonomous neurons, which allows for rapid state transitions of neural populations between successive chaotic basins of attraction along itinerant trajectories. The small fraction of covariant activity is extracted by spatial integration upon axonal transmission over divergent–convergent pathways, through which a remarkable improvement in signal-to-noise ratio is achieved. The raw traces of local activity show little evidence for synchrony, other than zero-lag correlation, which appears to be largely a statistical artifact. Brains rely less on tight phase-locking of small numbers of periodically firing neurons and more on low degrees of cooperativity achieved by order parameters influencing very large numbers of neurons. Brains appear to be indifferent to and undisturbed by widely varying time and phase relations between individual neurons and even large semi-autonomous areas of cortex comprising their mesoscopic neural masses.
EFFECTS OF DISTURBING AUDITORY NOISE ON THE COMPLEXITY OF ELECTROCORTICAL ACTIVITY
Authors: MÜLLER V. , KOTCHOUBEY B. , PERELMOUTER J. , LUTZENBERGER W. , BIRBAUMER N. , SCHICK A. , RECKHARDT C.
Published: April 2003

The effects of disturbing noise on the nonlinear electrical brain (EEG) dynamics were investigated in a sample of 12 healthy volunteers. The prediction that a high intensity noise increases the dimensional complexity of brain activity as compared to a low intensity noise, was confirmed using a deterministic chaos algorithm. Further, there was a tendency for rest conditions to have a higher dimensional complexity than the condition in which the low-intensity noise was presented. Although a Fourier-analysis of the EEG revealed a difference in the alpha power between the rest condition at the end of the experiment and the noise conditions, no effect of noise intensity on the EEG power spectrum was obtained. The data indicate that the disturbing effect of a loud noise results in the recruitment of additional cortical networks and thus increases the complexity of cortical cell assemblies.
THE CASE FOR A POSITIVE COSMOLOGICAL Λ-TERM
Authors: SAHNI VARUN , STAROBINSKY ALEXEI
Published: April 2003

Recent observations of Type 1a supernovae indicating an accelerating universe have once more drawn attention to the possible existence, at the present epoch, of a small positive Λ-term (cosmological constant). In this paper we review both observational and theoretical aspects of a small cosmological Λ-term. We discuss the current observational situation focusing on cosmological tests of Λ including the age of the universe, high redshift supernovae, gravitational lensing, galaxy clustering and the cosmic microwave background. We also review the theoretical debate surrounding Λ: the generation of Λ in models with spontaneous symmetry breaking and through quantum vacuum polarization effects — mechanisms which are known to give rise to a large value of Λ hence leading to the "cosmological constant problem." More recent attempts to generate a small cosmological constant at the present epoch using either field theoretic techniques, or by modelling a dynamical Λ-term by scalar fields are also extensively discussed. Anthropic arguments favouring a small Λ-term are briefly reviewed. A comprehensive bibliography of recent work on Λ is provided.
ENERGY LEVEL QUASI-CROSSINGS: ACCIDENTAL DEGENERACIES OR SIGNATURE OF QUANTUM CHAOS?
Authors: MANFREDI V. R. , SALASNICH L.
Published: April 2003

In the field of quantum chaos, the study of energy levels plays an important role. The aim of this review is to critically discuss some of the main contributions regarding the connection between classical dynamics, semi-classical quantization and spectral statistics of energy levels. In particular, we analyze in detail degeneracies and quasi-crossings in the eigenvalues of quantum Hamiltonians which are classically non-integrable.
INTERVAL METHODS IN KNOWLEDGE REPRESENTATION
Authors: KREINOVICH VLADIK
Published: April 2003

This section is maintained by Vladik Kreinovich. Please send your abstracts (or copies of papers that you want to see reviewed here), to vladik@cs.utep.edu, or by regular mail to: Vladik Kreinovich, Department of Computer Science, University of Texas at El Paso, El Paso, TX 79968, USA.
OPTICAL ANISOTROPY AND FOUR POSSIBLE ORIENTATIONS OF A NEMATIC LIQUID CRYSTAL ON THE SAME FILM OF A PHOTOCHROMIC CHIRAL SMECTIC POLYMER
Authors: BLINOV LEV M. , BARBERI RICCARDO , KOZLOVSKY MIKHAIL V. , LAZAREV VLADIMIR V. , DE SANTO MARIA P.
Published: April 2003

Spin coated films of a chiral comb-like liquid crystalline copolymer containing azobenzene chromophores in its side chains are optically isotropic in their twisted smectic-like glassy state. In contact with a nematic liquid crystal (5CB, E7, MBBA) they provide a degenerate planar orientation. When irradiated by unpolarized UV light, they orient the same nematics homeotropically. Treated with linearly polarized UV light they orient nematics homogeneously with the director along the electric vector of the exciting light. After a combined irradiation first with unpolarized UV light and then with linearly polarized visible light, the films again provide a homogeneous liquid crystal orientation, this time with the director perpendicular to the visible light electric vector. The phenomena observed are related to the light induced optical anisotropy. Two main processes are responsible for the anisotropy (1) a UV light depletion of trans-isomers of the azobenzene chromophores from the chosen direction and (2) a reorientation of the chromophores by polarized visible light.
EFFICIENT GENERATION OF COHERENT BLUE AND GREEN LIGHT BASED ON FREQUENCY CONVERSION IN KTiOPO4 CRYSTALS
Authors: DING YUJIE J. , MU XIAODONG , GU XINHUA
Published: April 2003

We review our recent results on efficient generation of coherent blue/green light based on different configurations and structures. We have used second-harmonic generation with forward or backward configuration in short-period periodically-poled bulk and wave-guide KTP to generate blue light. We have used backward second-harmonic generation to characterize periodically-segmented submicron KTP waveguides. By cascading second-harmonic generation and subsequent sum-frequency generation, we have generated coherent blue light in KTP and/or Ce:KTP crystals. We have also studied damage threshold of bulk KTP; we hope that we can eventually use it towards efficient generation of cw coherent green light.
MULTIPHOTON EFFECTS IN THE POLYDIACETYLENE POLY BIS(P-TOLUENE SULFONATE) OF 2,4-HEXADIYNE-1,6-DIOL (PTS)
Authors: YOSHINO FUMIYO , POLYAKOV SERGEY , FRIEDRICH LARS , LIU MINGGUO , SHIM HOON , STEGEMAN GEORGE I.
Published: April 2003

Multiphoton absorption was investigated in single crystals of the polymer poly bis(p-toluene sulfonate) of 2,4-hexadiyne-1,6-diol (PTS). Using modified growth and polymerization techniques, high optical quality crystals were grown and their linear absorption spectrum measured. Very large four-photon absorption was measured using Z-scan with a value of α4=0.3 cm 5/ GW 3 obtained at 1600 nm. From the known one and two-photon absorption spectra, the three- and four-photon spectra are predicted to overlap. This leads to three-photon enhanced, four-photon absorption which is interpreted as the mechanism responsible for such large four-photon absorption.
FEMTOSECOND TWO-PHOTON INDUCED LUMINESCENCE SPECTROSCOPIC STUDY OF CARRIER THERMALIZATION AND THE LIFETIME OF SPLIT-OFF HOLES IN GaAs
Authors: BURR KENT C. , TANG C. L.
Published: April 2003

Time-resolved two-photon induced luminescence spectroscopy is used to study the relaxation dynamics of holes in GaAs following valence-to-conduction band femtosecond pulse excitation in the near-infrared and heavy- and light-hole to split-off resonant transitions in the mid-infrared. It is shown that there is a rapid change in the electron and hole temperatures due to thermalization of the carrier distributions in the valence and conduction bands and that the collisions between the electrons and heavy holes are not elastic when scattering to the light hole band is possible. The lifetime of the split-off holes near the zone center is within the limits of 40 to 80 femtoseconds at room temperature.
COMBATTING NONLINEAR DISTORTION IN OPTICAL FIBRE TRANSMISSION SYSTEMS BY OPTIMUM DISPERSION COMPENSATION AND MODULATION FORMAT
Authors: RØYSET ARNE , HJELME DAG ROAR
Published: April 2003

The use of optical amplifiers in optical fibre communication systems has led to a situation where optical nonlinearities has become a major system limitation in long repeaterless high bitrate transmission systems. In this paper we present results from numerical studies of the interaction between dispersion and self phase modulation in 10–40 Gbit/s systems and presents design guidelines for such systems. We have found that optimised dispersion compensation can reduce the distortion caused by optical nonlinearities, hence allowing higher power levels in the fibre and thereby increasing the power budget and transmission distance.
FUNCTIONAL INEQUALITIES, SEMIGROUP PROPERTIES AND SPECTRUM ESTIMATES
Authors: WANG FENG-YU
Published: April 2003

This paper gives a reasonably self-contained account for some recent progress on functional inequalities, semigroup properties and spectrum estimates. Two sorts of functional inequalities are considered, they are actually equivalent and are general forms of Sobolev type inequalities. Semigroup properties, spectrum estimates and concentration of measures are described using these inequalities. Some criteria of functional inequalities and estimates of the spectral gap and the log-Sobolev constant are presented for diffusions on Riemannian manifolds and jump processes. Most yet unpublished results are reproved.
UN THÉORÈME de BOCHNER–MINLOS AVEC UNE CONDITION D'INTÉGRABILITÉ
Authors: OUERDIANE HABIB , REZGUI ANIS
Published: April 2003

Soit [Formula: see text] une fonction caractéristique définie sur un Fréchet nucléaire réel X. Si on suppose que [Formula: see text] est prolongeable par analycité au complexifié N de l'espace X et vérifie une condition de croissance de type exponentielle: [Formula: see text] où K ≥0, m >0, | |p étant une certaine norme de l'espace N et θ une fonction continue convexe satisfaisant certaines hyppothèses techniques.

Soit μ la mesure associée à [Formula: see text] par le théorème de Bochner–Minlos, on montre qu'elle vérifie la condition d'intégrabilité suivante: [Formula: see text] où θ* est la fonction conjuguée de θ, m' >0 et | |-q est une certaine norme de l'espace dual X' de X.

La réciproque de ce résultat est démontrée.
NOISE MEASUREMENTS FOR MATERIAL DIELECTRIC CHARACTERIZATION: APPLICATION TO A LIQUID CRYSTAL
Authors: GÉRARD LEROY , JOËL GEST , PIERRE TABOURIER
Published: April 2003

In this paper, we show how noise measurements can be used for the characterization of a dielectric material. This nonperturbative technique allows the determination of the real and imaginary parts of the complex permittivity from current and voltage noise measurements. This technique is illustrated hereafter for the case of an antiferroelectric liquid crystal.
MESOSCOPIC FLUCTUATIONS IN THE SPIN GLASS COPPER MANGANESE WITH GOLD
Authors: MERITHEW R. D. , FENIMORE P. W. , WEISSMAN M. B.
Published: April 2003

The temperature dependence of discrete spin fluctuation modes is investigated in the spin glass phase of CuMn, doped with Au to produce strong local anisotropy. As with the locally anisotropic spin glass AuFe, and unlike the nearly isotropic CuMn, individual few-state fluctuators are found and can be tracked vs. temperature. The kinetics follow Arrhenius laws, with normal attempt rates.
Evaluation of the Effects of Nateglinide on Postprandial Glycemia in Patients with Type 2 Diabetes mellitus: A Multicenter, Multinational, Non-Randomized, Non-Controlled Latin American Study
Authors: Islas-Andrade Sergio , Revilla-Monsalve Maria Cristina , Martínez de Hurtado Evelyn , Chacín Luis F. , Caminos Quenemari R. , Yupanqui Hernán , López Gloria , de la Torre Walter
Published: April 2003

One hundred and sixteen Latin American type 2 diabetic patients previously only on a diet were enrolled in this multicenter, multinational, nonrandomized, noncontrolled study. Only 109 completed the study. After 8 weeks of treatment with 120 mg of nateglinide, administered prior to each meal, the postprandial (2 h) glucose concentration decreased to 85.11 ± 5.65 mg/dl (p < 0.0001), and HbA1c values decreased to 1.06 ± 0.10% (p < 0.0001). No response differences were detected in relation to age, gender, or ethnicity, but we did encounter a better response in recently diagnosed patients (≤1 year). No serious adverse events were observed. We can, therefore, conclude that nateglinide is a well-tolerated, safe, and effective insulinotropic agent.
Anti-Inflammatory Effect and Low Ulcerogenic Activity of Etodolac, a Cyclooxygenase-2 Selective Non-Steroidal Anti-Inflammatory Drug, on Adjuvant-Induced Arthritis in Rats
Authors: Tachibana Masaki , Inoue Naoki , Yoshida Eri , Matsui Masami , Ukai Yojiro , Yano Junichi
Published: April 2003

Adjuvant arthritic rats are known to be more susceptible to gastric damage induced by non-steroidal anti-inflammatory drugs (NSAIDs) than are normal rats. We compared the relative gastric safety profile of etodolac with those of meloxicam, diclofenac sodium and indometacin in adjuvant arthritic rats and normal rats or mice. As a measure of the safety profiles of NSAIDs, we used the safety index, the ratio of the dose that elicits gastric mucosal lesions to the effective dose as an anti-inflammatory or analgesic compound. The anti-inflammatory or analgesic effects of NSAIDs were assessed by paw swelling in adjuvant arthritic rats, and either carrageenin-induced paw edema or brewer’s yeast-induced hyperalgesia, as well as acetic acid-induced writhing, in normal rats or mice. In addition, we also investigated the effects of these NSAIDs on human COX-1 and COX-2 activity. Etodolac and other NSAIDs inhibited paw swelling and caused gastric mucosal lesions in adjuvant arthritic rats in a dose-dependent manner. Etodolac showed the highest UD50 value and safety index among these NSAIDs in arthritic rats. In normal rats, etodolac also showed the highest UD50 value and safety index, except when its effects were assessed by acetic acid-induced writhing. Etodolac and meloxicam showed selectivity for human COX-2 over COX-1. In contrast, diclofenac sodium and indometacin were selective for COX-1. These results suggest that etodolac, a COX-2 selective NSAID, has anti-inflammatory effects with a better safety profile for the stomach than do non-selective NSAIDs, including diclofenac sodium and indometacin, in adjuvant arthritic as well as normal rats.
Characteristics, Management and Outcome of Patients with Prior Coronary Bypass Surgery Presenting with Acute Myocardial Infarction
Authors: Zahger Doron , Behar Solomon , Harpaz David , Leor Jonathan , Weiss A. Teddy , Gottlieb Shmuel
Published: April 2003

We compared the characteristics, management and outcome of patients with or without prior coronary artery bypass graft surgery (CABG) presenting with AMI to any coronary care unit in Israel, from four national surveys performed during 1992–1998. Of 5,396 patients, 171 (3.2%) had prior CABG, 39 of whom received thrombolysis. Thrombolysis was administered less often in patients with prior CABG, but the utilization of coronary angiography was similar. Mortality rates were higher in patients with prior CABG, particularly among those given thrombolysis. The use of coronary angiography was a strong independent predictor of survival, but its utilization was similar in patients with or without prior CABG. Patients with prior CABG constitute a small minority among current AMI patients. They are sicker and their mortality is higher compared to patients without prior surgery, especially among those given thrombolysis. Coronary angiography is associated with improved outcome in these patients but is currently used to the same extent as in patients without prior surgery.
Comparison of the Bactericidal Activity of Moxifloxacin and Levofloxacin against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Klebsiella pneumoniae
Authors: Lemmen S.W. , Häfner H. , Klik S. , Lütticken R. , Zolldann D.
Published: April 2003

In addition to MIC and MBC tests in this study the serum bactericidal activity of 3.1 µg/ml of moxifloxacin or 5.2 µg/ml of levofloxacin was determined against ten susceptible strains of S. aureus, S. epidermidis, E. coli and K. pneumoniae. Moxifloxacin achieved markedly better activity against S. aureus and S. epidermidis as compared to levofloxacin. Activity of moxifloxacin against E. coli and K. pneumoniae was excellent but not superior to levofloxacin. In conclusion both fluorquinolones are highly effective against E. coli and K. pneumoniae, moxifloxacin being superior with respect to gram-positives like S. aureus and S. epidermidis.
Survey of High- and Low-Level Mupirocin-Resistant Strains of Methicillin-Resistant Staphylococcus aureus in 15 Japanese Hospitals
Authors: Fujimura Shigeru , Watanabe Akira
Published: April 2003

Background: The extent of mupirocin-resistant methicillin-resistant Staphylococcus aureus (MRSA) in countries using mupirocin only for the eradication of nasal carriage of MRSA is unknown. Methods: During 1997, 1998, 1999, 2000, and 2001, 1,368 strains of MRSA were isolated from 15 general hospitals in the Tohoku area of Japan and tested for susceptibility to mupirocin. Results: The isolation of low-level mupirocin resistance was 0.8% in 1997, 1.1% in 1998, 0.7% in 1999, 4.0% in 2000, and 2.4% in 2001. For the first 3 years it was about 1%. However, the isolation rate of low-level mupirocin resistance in MRSA increased dramatically in 2000. High-level mupirocin resistance was not detected during these years. Conclusion: Most patients from whom low-level mupirocin resistant MRSA were found in 2000 and 2001 had previously received mupirocin treatment for eradicating nasal carriage of MRSA, and these strains were isolated from sputum or the pharynx. This result indicates that mupirocin treatment is likely to be one of the causes of mupirocin resistance and, therefore, the development of low-level mupirocin resistance in MRSA isolated from sputum or the pharynx should be considered when using mupirocin in order to improve the control of the spread of MRSA in hospitals.
Spontaneous Intracerebral Hemorrhage in Northeast Malaysian Patients: A Four-Year Study
Authors: Muiz A.J. , Abdullah J. , Naing N.N. , Ghazaime G. , Ariff A.R.
Published: April 2003

The aim of this study was to compare nonsurgical versus stereotactic aspiration of intracerebral hematomas in relation to clinical aspects, computed tomographic imaging features of the brain, laboratory parameters and specific risk factors that may influence the outcome in southeast Asian Malay patients. Fifty-five of the patients with intracerebral hemorrhage (ICH) underwent stereotactic aspiration and 57 did not. Analysis was done on risk factors, locations and treatments of ICH, and the final outcomes measured by the Glasgow Outcome Scale. A total of 112 patients were evaluated. Mean age was 52 years with ages ranging from 12 to 80 years. Hypertension was seen in 60.7% of patients with ICH. The mortality rate was 25% by 3 months. 58.9% had a poor final outcome, while 41.1% had a good outcome. The selected variables were incorporated into models generated by multiple logistic regression method analysis to define the significant predictors of outcome. Significant predictors of outcome were the Glasgow Coma Scale score on admission, the duration of surgery and the total volume of the hematoma. Significant predictors of mortality were high total white blood cell differential count, low plasma protein, and high plasma lactate dehydrogenase and brain edema. The study suggests that stereotactic aspiration of patients with ICH does not offer any definite advantage over conservative treatment.
Dementia and Disability: Impact on Mortality
Authors: Noale M. , Maggi S. , Minicuci N. , Marzari C. , Destro C. , Farchi G. , Scafato E. , Baldereschi M. , Di Carlo A. , Crepaldi G.
Published: April 2003

Dementia is known to be associated with excess mortality. Physical disability, as a marker of dementia severity, is often considered the last step on the way from disease to death. The objective of this study was to investigate the direct effect of dementia on mortality in a population-based study, carried out in Italy, with a sample of 5,632 individuals aged 65–84 years. At 4-year follow-up, 998 participants had died. The independent predictors of death were: age (75–84 years; HR 2.63, CI = 2.11–3.27), male sex (HR 1.45, CI = 1.22–1.74), coronary heart disease (HR 1.61, CI = 1.34–1.94), moderate and severe instrumental activities of daily living disability (HR 1.98, CI = 1.30–3.03 and HR 3.26, CI = 2.09–5.09, respectively), diabetes in subjects with a survival time greater than 23 months (HR 0.68, CI = 0.43–1.08) and dementia (HR 2.07, CI = 1.62–2.66). These data provide evidence that dementia per se, independently from physical disability, is a strong predictor of death in the elderly.
Serum Insulin-Like Growth Factor Levels Do Not Predict Functional Recovery after Hospitalization in Nonagenarian Patients
Authors: Formiga F. , Acebes G. , Alia P. , Blancas D. , Pujol R. , Navarro M.A.
Published: April 2003

Aim: To analyze the insulin-like growth factor 1 (IGF-1) serum levels in nonagenarian patients and to investigate the predictive capacity of this measure to assess the functional recovery of this population following hospitalization. Methods: We performed a prospective study in 60 consecutive nonagenarian patients admitted for medical or surgical diseases. We assessed IGF-1 serum levels and nutritional status. The functional status was assessed using the Barthel index. Thirty-four patients were reinvestigated 3 months after discharge from hospital. Results: The mean levels of IGF-1 were lower in nonagenarians than in younger patients. No relationship was found between IGF-1 levels and nutritional status. The decline in Barthel index values 3 months after discharge from hospital did not correlate with serum levels of IGF-1 on admission. Conclusion: IGF-1 serum levels in nonagenarian patients do not predict functional recovery after hospitalization.
Simple Basic Peptides Activate DNA Strand Exchange
Authors: Tajima Kaori , Kim Won Jong , Sato Yuichi , Akaike Toshihiro , Maruyama Atsushi
Published: April 2003

The simple cationic peptides containing arginine moieties were proved to accelerate DNA strand exchange reaction.
Evaluation of Bioavailability of Heavy Metals in Soil by in vitro Screening Test
Authors: Yamada Aya , Ono Yoshiro , Kida Akiko , Namiki Kenji
Published: April 2003

The bioavailability of cadmium, lead, and chromium leaching from soil was determined by an in vitro experiment utilizing artificial stomach and small intestine solutions. The dissolved concentrations of these metals in the model stomach + small intestine condition was lower than those found in the model stomach as a result of the re-adsorption to the soil by titration from pH 2.0 to 7.0.
Terminal fall velocity and the FASTEX cyclones
Authors: Protat A. , Lemaîitre Y. , Bouniol D.
Published: April 2003

Knowledge of water‐drop and ice‐crystal terminal velocities is particularly important for an adequate representation of particle sedimentation in cloud‐resolving and large‐scale models. In this paper, a new method is proposed to retrieve terminal fall velocity from airborne‐Doppler‐radar observations. To extract the terminal fall velocity from the Doppler information, which mixes the three wind components and the terminal fall velocity, statistical considerations are introduced, stating that for a long sampling time span (a whole aircraft mission, for instance) and for moderate storms such as stratiform precipitation, the mean vertical air motions should vanish with respect to the mean terminal fall velocity. Statistical power‐law relationships between terminal fall speed and radar reflectivity are then developed, as well as profiles of mean terminal fall velocity. This underlying hypothesis of the method is validated with in situ measurements of the vertical wind component, averages of convective‐scale retrievals of the vertical wind component, and terminal fall speed–radar reflectivity (VT–Z) relationships derived from in situ measurements of the drop size distribution. These comparisons all indicate that the vertical air motion can indeed be neglected with respect to the terminal fall speed.

A detailed analysis of the statistical relationships obtained in liquid and ice phases for six frontal cyclones at different stages of development shows that a ‘universal’ VT–Z rain relationship can be proposed for North Atlantic frontal cyclones at mature stage. This result and further arguments developed in the paper suggest that the drop size distributions are ‘equilibrium’ distributions. In the ice phase, such a ‘universal’ relationship is not found. It is nevertheless suggested in this study that such a general relationship might be derived if the frontal cyclones are split into categories depending on their stage of development. These VT–Z ‘universal’ relationships can be introduced in large‐scale model parametrization schemes in order to better describe the sedimentation of ice and water and dynamical–microphysical interactions occurring within North Atlantic frontal cyclones.

Finally, a procedure is proposed to estimate the most representative type of ice particle from 2D‐P in situ sensor and airborne‐Doppler‐radar measurements. It consists of calculating the mean flight‐level Z and the VT–Z relationships in the ice phase for several theoretical ice habits, and to identify the ice habit that reasonably reproduces both the radar‐derived mean flight‐level Z and VT–Z ice relationship. Copyright © 2003 Royal Meteorological Society
Nurse-led sexual health care: international perspectives
Authors: Miles Kevin , Knight Vickie , Cairo Irina , King Irene
Published: April 2003

Nurses as first-line care providers for the treatment of sexually transmitted infections are a relatively new concept in the United Kingdom (UK). However, for over 25 years, services in other countries have been empowering nurses to work as autonomous practitioners, capable of dealing with patients presenting with a range of sexual health conditions and issues without necessarily seeking the advice or input of a doctor. This paper will present the observations of nurse-led services in Amsterdam, Seattle and Sydney. It will discuss how service providers in the UK can learn from the experiences of international colleagues and will argue why trained and experienced genitourinary medicine nurses need to advance their role and be better integrated as first-line care providers.