bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Acyclic Nucleoside and Nucleotide Analogs Derived from 6-Amino-7H-purine-8(9H)-thione and 8-(Methylsulfanyl)adenine
Authors: Janeba Zlatko , Holý Antonín , Masojídková Milena
Published: July 2002

Reaction of 8-bromoadenine derivatives1with thiourea in ethanol or butanol was used for the synthesis of the correspondingN9-substituted 6-amino-7H-purine-8(9H)-thiones2. 8-(Methylsulfanyl)adenine derivatives3were prepared by reaction of thiones2with iodomethane in 1 M sodium methoxide or in aqueous 1.5 M potassium hydroxide. Alkylation of 6-amino-7H-purine-8(9H)-thione (2a) proceeds preferentially on the sulfur atom. Under similar conditions, alkylation of 8-(methylsulfanyl)adenine (3a) with diverse alkylation agents affordedN9-substituted adenine derivatives3and6, andN3-substituted adenine derivatives5and7. 8,3'-S-Anhydro derivatives9were prepared in good yields by cyclization of 6-amino-7H-purine-8(9H)-thiones2dand2funder the Mitsunobu reaction conditions.
Polarographic and Voltammetric Determination of 1-Nitropyrene
Authors: Barek Jiří , Zima Jiří , Moreira Josino C. , Muck Alexandr
Published: July 2002

The polarographic behaviour of 1-nitropyrene was investigated by tast polarography, differential pulse polarography (both with a dropping mercury electrode), differential pulse voltammetry, and adsorptive stripping voltammetry (both with a hanging mercury drop electrode). Optimum conditions have been found for its determination by the given methods in the concentration ranges 2-100, 0.2-100, 0.1-10, and 0.001-0.01 μmol l-1, respectively.
Cytostatic 6-Arylpurine Nucleosides III. Synthesis and Structure-Activity Relationship Study in Cytostatic Activity of 6-Aryl-, 6-Hetaryl- and 6-Benzylpurine Ribonucleosides
Authors: Hocek Michal , Holý Antonín , Votruba Ivan , Dvořáková Hana
Published: July 2002

A series of fifteen 6-aryl-, 6-hetaryl- and 6-benzylpurine ribonucleosides has been prepared by Pd-catalyzed cross-coupling reactions of 6-chloro-9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)- purine with arylboronic acids, hetarylzinc halides, hetarylstannanes or benzylzinc halides followed by deprotection. Structure-activity relationship study revealed that besides 6-(4-substituted phenyl)purine nucleosides, also some 6-hetaryl- and 6-benzylpurine ribonucleosides possess considerable cytostatic activity.
Effects of octreotide on responses to colorectal distension in the rat
Authors: Su X , Burton M B , Gebhart G F
Published: July 2002

BACKGROUND AND AIMS

It has been suggested that the analgesic effect of the somatostatin analogue octreotide in visceral pain involves peripheral mechanisms. We evaluated the effect of octreotide on responses to noxious colorectal distension in rats.

METHODS

In a behavioural study, pressor and electromyographic responses to colorectal distension were evaluated before and after intravenous or intrathecal administration of octreotide. In pelvic nerve afferent fibre recordings, responses of mechanosensitive fibres innervating the colon to noxious colorectal distension (80 mm Hg, 30 seconds) were tested before and after octreotide.

RESULTS

Octreotide was ineffective in attenuating responses to colorectal distension in either normal or acetic acid inflamed colon when administered intravenously but attenuated responses when given intrathecally. Administration of octreotide over a broad dose range (0.5 μg/kg to 2.4 mg/kg) did not alter responses of afferent fibres to noxious colorectal distension in untreated, or acetic acid or zymosan treated colons.

CONCLUSIONS

In the rat, octreotide has no peripheral (pelvic nerve) modulatory action in visceral nociception. The antinociceptive effect of octreotide in this model of visceral nociception is mediated by an action at central sites.
An optimal construction resource leveling scheduling simulation model
Authors: Leu Sou-Sen , Hung Tzung-Heng
Published: July 2002

To meet the physical limits of construction resources, to avoid day-to-day fluctuation in resource demands, and to maintain an even flow of application for construction resources, resource leveling is needed in the construction industry. Traditional resource leveling models assume activity durations to be deterministic. Nevertheless, activity duration may be uncertain, owing to variations in the overall environment, such as weather, site congestion, and productivity level. A new optimal construction resource leveling model is proposed in this paper, in which the combinative effects of both uncertain activity duration and resource leveling are taken into consideration. Monte Carlo simulation is used to model the uncertainties of activity duration. A searching technique using genetic algorithms (GAs) is then adopted to search for the impact of uncertain activity durations on the probabilistic optimal resource leveling indices. The model can effectively provide probabilistic optimal resource leveling indices for multiple construction resources subjected to the objective of resource leveling, and the impact of influence factors on the probabilistic resource-leveling scheduling problems.Key words: resource leveling, genetic algorithms, simulation, probabilistic scheduling.
Monte-Carlo calculation of the primary yields of H2O2 in the 1H+, 2H+, 4He2+, 7Li3+, and 12C6+ radiolysis of liquid water at 25 and 300°C
Authors: Meesungnoen Jintana , Jay-Gerin Jean-Paul , Filali-Mouhim Abdelali , Mankhetkorn Samlee
Published: July 2002

Monte-Carlo simulations are used to calculate the primary yield of hydrogen peroxide (GH2O2) of the radiolysis of pure, deaerated liquid water as a function of linear energy transfer (LET) of the incident radiation over the range ~0.3100 keV µm1, at 25 and 300°C. The radiations include 1H+, 2H+, 4He2+, 7Li3+, and 12C6+ ions with energies from 0.17 MeV to 3.6 GeV. At 25°C, it is found that our GH2O2 values, calculated with protons of different initial energies, show a monotonic increase as a function of LET, in agreement with the commonly assumed expectation of an increase in molecular yields with increasing LET. Our calculated H2O2 yields at 300°C increase significantly faster with LET than do their corresponding 25°C values, showing that the temperature dependence of GH2O2 at higher LET is less than for low-LET radiation. We also report our results on the temporal variations of the H2O2 yields, in the interval ~1 × 1013  1 × 106 s, at 25 and 300°C and for the different types of radiation considered. Finally, we find that for incident ions of equal LET > 10 keV µm1, GH2O2 decreases as the ion velocity increases, from protons (or deuterons) to carbon ions. These differences produced in GH2O2 by changing the type of radiation are explained by the greater mean energy of secondary electrons from the higher velocity ions, which penetrate to a greater average distance from the actual particle track, with a corresponding decrease in molecular yields. Our calculated GH2O2 values compare generally well with the experimental data available from the literature and are also in good accord with the predictions of deterministic diffusion-kinetic model calculations reported earlier.Key words: liquid water, radiolysis, primary yields, hydrogen peroxide (H2O2), linear energy transfer (LET), accelerated protons and heavy ions, temperature, Monte-Carlo simulations.
THE REGULARITY OF TWO-WAY NONDETERMINISTIC TREE AUTOMATA LANGUAGES
Authors: BRÜGGEMANN-KLEIN ANNE , WOOD DERICK
Published: July 2002

We establish that regularly extended two-way nondeterministic tree automata with unranked alphabets have the same expressive power as regularly extended nondeterministic tree automata with unranked alphabets alphabets. We obtain this results by establishing regularly extended versions of a congruence on trees and of a congruence on, so called, views. Our motivation for the study of these tree models is the Extensible Markup Language (XML), a metalanguage for defining document grammars. Such grammars have regular sets of right-hand sides for their productions and tree automata provide an alternative and useful modeling tool for them. In particular, we believe that they provide a useful computational model for what we call caterpillar expressions.
4D LOCAL QUANTUM FIELD THEORY MODELS FROM COVARIANT STOCHASTIC PARTIAL DIFFERENTIAL EQUATIONS I: GENERALITIES
Authors: GIELERAK R. , ŁUGIEWICZ P.
Published: July 2002

A general class of covariant stochastic partial differential equations in Euclidean space-time dimension D=4 is selected and solutions of them are discussed. In particular we demonstrate a possibility of an analytic continuation of the moments of the constructed solutions to the Minkowski space-time. That gives rise to systems of tempered distributions obeying a substantial part of Wightman axioms. Specific models appropriate for vector, Higgs-like and Maxwell-like fields are described in detail. Covariant schemes for solving rectangular systems of equations are presented. Those ideas lead in particular to clarification of the concept of gauge-invariance in the present context. The explicit forms of Wightman distributions are obtained and used to prove the Hilbert Space Structure Condition. Some explicitly computable covariant models of extended random objects like loops, membranes and bags are presented.
STARK HAMILTONIAN WITH UNBOUNDED RANDOM POTENTIALS
Authors: HISLOP PETER D. , NAKAMURA SHU
Published: July 2002

Spectral properties of one-dimensional Schrödinger operators with unbounded potentials are studied. The main example is the Stark Hamiltonian with unbounded Anderson-type random perturbations. In this case, it is shown that if the perturbation is o(x) then the spectrum is the real line and absolutely continuous except for eigenvalues with no accumulation points. If the perturbation is larger than O(x), then the Hamiltonian has no absolutely continuous spectrum. The methods of proof involve the Mourre estimate and trace-class perturbation theory as recently used by Simon and Spencer.
MASSLESS PARTICLES, ELECTROMAGNETISM, AND RIEFFEL INDUCTION
Authors: LANDSMAN N.P. , WIEDEMANN U.A.
Published: July 2002

The connection between space-time covariant representations (obtained by inducing from the Lorentz group) and irreducible unitary representations (induced from Wigner’s little group) of the Poincaré group is re-examined in the massless case. In the situation relevant to physics, it is found that these are related by Marsden-Weinstein reduction with respect to a gauge group. An analogous phenomenon is observed for classical massless relativistic particles. This symplectic reduction procedure can be (‘second’) quantized using a generalization of the Rieffel induction technique in operator algebra theory, which is carried through in detail for electromagnetism.

Starting from the so-called Fermi representation of the field algebra generated by the free abelian gauge field, we construct a new (‘rigged’) sesquilinear form on the representation space, which is positive semi-definite, and given in terms of a Gaussian weak distribution (promeasure) on the gauge group (taken to be a Hilbert Lie group). This eventually constructs the algebra of observables of quantum electromagnetism (directly in its vacuum representation) as a representation of the so-called algebra of weak observables induced by the trivial representation of the gauge group.
LINEAR CONNECTIONS ON THE TWO-PARAMETER QUANTUM PLANE
Authors: GEORGELIN YVON , WALLET JEAN-CHRISTOPHE , MASSON THIERRY
Published: July 2002

We apply a recently proposed definition of a linear connection in non-commutative geometry based on the natural bimodule structure of the algebra of differential forms to the case of the two-parameter quantum plane. We find that there exists a non-trivial family of linear connections only when the two parameters obey a specific relation.
DEFORMED KORTEWEG-DE VRIES EQUATION WITH SYMBOLIC COMPUTATION
Authors: GAO YI-TIAN , TIAN BO
Published: July 2002

The Korteweg-de Vries-typed equations are the most important class of nonlinear evolution equations, with numerous applications in physical and engineering sciences. In this paper, for the deformed Korteweg-de Vries equation of the form [Formula: see text], we make use of computerized symbolic computation and obtain several families of new exact analytic solutions, some of which are solitonic.
MINIMAL ELECTROWEAK SYMMETRY BREAKING MODEL IN EXTRA DIMENSIONS
Authors: CHENG HSIN-CHIA
Published: July 2002

We show that if the Standard Model gauge fields and fermions propagate in extra dimenions, a composite Higgs field with the correct quantum number can arise naturally as a bound state due to the strong gauge interactions in higher dimensions. The top quark mass and the Higgs mass can be predicted from the infrared fixed points of the renormalization group equations. The top quark mass is in good agreement with the experimental value, and the Higgs boson mass is predicted to be ~ 200GeV. There may be some other light bound states which could be observed at upcoming collider experiments.
A UNIFIED DESCRIPTION OF STATIC AND DYNAMIC PROPERTIES OF FERMI LIQUIDS
Authors: DUPUIS N.
Published: July 2002

In Landau's phenomenological Fermi-liquid theory (FLT), most physical quantities are derived from the knowledge of the energy variation δE[δn] corresponding to a change δn of the quasi-particle (QP) distribution function n≡{nkσ}. We show that the internal energy E[n] (or, more precisely, the thermodynamic potential Φ[n]), expressed as a function of the QP distribution n, can be interpreted as an effective potential (in the sense of field theory), which is obtained from the free energy by a Legendre transformation. This allows to obtain explicitly δΦ (or δE) starting from a microscopic Hamiltonian and to relate the Landau f function to the forward-scattering two-particle vertex without considering the collective modes as in the standard diagrammatic derivation of FLT. Out-of-equilibrium properties are obtained by extending the definition of the effective potential to space- and time-dependent configurations. Φ[n] is then a functional of the Wigner distribution function n≡{nkσ (r,t)}. It contains information about both the static and dynamic properties of the Fermi liquid. In particular, it yields the quantum Boltzmann equation satisfied by nkσ (r, t). Finally, we show how δΦ[δn] can be derived (in the static case) using a finite-temperature renormalization-group approach. In agreement with previous results based on this technique, we find that the Landau f function is defined by the fixed-point value of the Ω-limit of the forward-scattering two-particle vertex.
STRIPES, PSEUDOGAP AND SC-SDW RESONANCE IN HTSC PEROVSKITES
Authors: MAZOV L. S.
Published: July 2002

The significant role of spin stripes in HTSC system is emphasized. The evidence for spin density wave (SDW) nature of pseudogap is presented. The dependence of CuO2 lattice modulation amplitude on the temperature and applied magnetic field is studied. The indication to possible SDW-SC resonance is obtained. The possible amplification of Tc with using of artificial magnetic stripes with taking into account their dynamic nature is proposed. An example of twofold amplification of Tc in thin single-crystalline film of La-based cuprate is presented.
STRUCTURE AND SUPERCONDUCTING CHARACTERISTICS OF A DEFECTIVE (Bi1.6Pb0.4)(Sr1.8Ba0.2)(Ca1.96Lu0.04)Cu3Oy SUPERCONDUCTOR
Authors: CIURCHEA D.
Published: July 2002

Full pattern decomposition was applied to the X-ray diffraction patteren of a single phase orthorhombic ( Bi 1.6 Pb 0.4)( Sr 1.8 Ba 0.2)( Ca 1.96 Lu 0.04) Cu 3 O y superconductor. Delocalization of the Sr atoms induces terracing of the Cu/Ca/Cu superconducting stacking up to 0.6 Å, in the range of the c-axis coherence length. This yields a three dimensional character of the conduction evidenced in the resistivity measurements also. The effect is direct consequence of the loss of symmetry implied by the orthorhombic structure.
NONCLASSICAL PROPERTIES AND HOLE BURNING IN THE REAL AND IMAGINARY BINOMIAL STATES
Authors: LIAO JING , WANG XIAOGUANG , WU LING-AN , PAN SHAO-HUA
Published: July 2002

We study the nonclassical properties of the real and imaginary binomial states formed by a superposition of the binomial states of Stoler et al. Their sub-Poissonian statistics and squeezing properties are studied in detail. These states have holes in the photon-number distribution, due to quantum interference between the two conjugate components. The corresponding ladder operator formalisms of these states are given.
NUCLEAR MATTER CALCULATION WITH THE EXACT PAULI OPERATOR IN THE BRUECKNER THEORY
Authors: SUZUKI K. , OKAMOTO R. , KOHNO M. , NAGATA S.
Published: July 2002

Exact expression of the Pauli exclusion operator Q in the nuclear matter calculation is presented. Numerical calculations of the G matrix with the exact Q operator are carried out by employing the Bonn B and a C NN potentials. It is observed that the exact treatment of the operator Q brings about non-negligible and attractive contributions to the binding energy.
BOSONS IN A LATTICE: EXCITON-PHONON CONDENSATE
Authors: ROUBTSOV D. , LÉPINE Y.
Published: July 2002

We explore a nonlinear field model to describe the interplay between the ability of excitons to be Bose-condensed and their interaction with other modes of a crystal. We apply our consideration to the long-living para-excitons in Cu2O . Taking into account the exciton-phonon interaction and introducing a coherent phonon part of the moving condensate, we derive quasi-stationary equations for the exciton-phonon condensate. These equations can support localized solutions, and we discuss the conditions for the moving inhomogeneous condensate to appear in the crystal. The stability conditions of the moving condensate are analyzed by use of Landau arguments, and Landau critical parameters appear in the theory. Finally, we apply our model to describe the recently observed interference and strong nonlinear interaction between two coherent exciton-phonon packets in Cu2O .
INVERSE FORMULATION OF THE GREEN'S FUNCTION THEORY: EXACT SOLUTION FOR THE BETHE LATTICE
Authors: ŠAMAJ L.
Published: July 2002

We study the tight-binding Hamiltonian H=∑j|j> ∊jVjk < k | defined on the Bethe lattice of an arbitrary coordination number; the hopping elements Vjk are nonzero (and constant) only for j,k being the nearest-neighbor sites and the energies ∊j are considered to be site-dependent. The Green's function (z-H)-1 problem is solved explicitly in the inverse form, with diagonal matrix elements {} as controlling (prescribed) variables. Namely: (i) the inverse profile relation, i.e. z-∊j versus diagonal matrix elements, is obtained in a local form; (ii) the off-diagonal matrix elements { } are shown to exhibit a simple factorization property in terms of the diagonal ones.
IMPURITY LEVELS IN A PARABOLIC QUANTUM DOT UNDER ACTION OF A STRONG MAGNETIC FIELD
Authors: KAZARYAN E. M. , PETROSYAN L. S. , SARKISYAN H. A.
Published: July 2002

The impurity states in quantum dot with parabolic confinement were studied in adiabatic approximation. The analytical expressions for the energy of ground and excited states were obtained. It was shown, that the influence of walls results in raising the ground energy level.
ULTRAFAST PHOTO-INDUCED ABSORPTION CHANGE IN INORGANIC-ORGANIC MUTIPLE QUANTUM WELL COMPOUND
Authors: KAJITA MASAKAZU , SHIMIZU MAKOTO , NEOGI ARUP , ISHIHARA TERUYA
Published: July 2002

We have performed pump-and-probe measurements to investigate ultrafast excitonic non-linearity expected in an inorganic-organic compound (C6H5C2H4NH3)2PbI4 , which has huge exciton binding energy (220 meV) and oscillator strength (0.5 per formula unit) by virture of the small dielectric constant in the barrier layer (the dielectric confinement or image charge effect). When the pump photon energy is set at the exciton level at 2.37 eV or above the band gap, the absorption decreases immediately after the pump due to the phase space filling effect and retrieves in a few ps. The retrieval time is ascribed to the ultrafast radiative lifetime of the exciton level. The second exciton absorption at 2.39 eV exhibits induced absorption when the pump is at the first exciton band, which may provide a hint to the origin of the band.
OPTICAL SECOND HARMONIC SPECTROSCOPY OF THE ANATASE TiO2(101) FACE
Authors: MIZUTANI G. , ISHIBASHI N. , NAKAMURA S. , SEKIYA T. , KURITA S.
Published: July 2002

We have investigated electronic levels of the H 2 O /anatase TiO 2 (101) interface by optical second harmonic spectroscopy. We see a sharp rise of SH intensity above the SH phonon energy 2ℏω~3.6 eV . According to our previous analysis, the SH signal from this face originates mainly from the H 2 O/TiO 2 (101) interface. The sum frequency intensity also shows a rise at ℏω1+ℏω2~3.6 eV . Thus the observed sharp rise of the SH intensity is due to a resonance of an interface band gap at 3.6eV. The energy of this interface band gap is larger than that of the bulk band gap, 3.2eV.
EFFECT OF THE Fe AND Zn CODOPED ON THE INTERGRANULAR PROPERTIES FOR (Bi1.6Pb0.4)(Sr1.8Ba0.2)Ca2(Cu1-x-yZnxFey)3Oz SUPERCONDUCTING SYSTEM
Authors: POP A. V. , POP V.
Published: July 2002

Systematic measurements of the AC susceptibility as a function of temperature and magnetic field amplitude H ac for the Fe and Zn codoped ( Bi 1.6 Pb 0.4)( Sr 1.8 Ba 0.2) Ca 2( Cu 1-x-y Zn x Fe y)3 O z (x = 0.00;0.02 and y = 0.00;0.01) system are reported. Above H ac = 200 A/m, the linear dependence of T p for maximum of imaginary χ′′(T) peak as a function of AC field amplitude agree with Muller critical state model. The intergrain pinning force density decreases in doped and codoped samples.
DIAMOND-FIBRE REINFORCED PLASTIC COMPOSITES
Authors: MAY P. W. , HALL M. , SMITH D. J.
Published: July 2002

Diamond fibre reinforced poly (methylmethacrylate) (PMMA, perspex) composite blocks (100 × 10 × 4 mm) have been fabricated by embedding CVD diamond coated tungsten wires within a perspex matrix. Various volume fractions of diamond have been used, as well as varying positions of the fibres within the composite. We find that even 1% fibre volume fraction can lead to an increase in the Young's modulus of the composite of a factor of 6.
TETRAHEDRAL AMORPHOUS CARBON (Ta-C) ULTRA THIN FILMS FOR SLIDER OVERCOAT APPLICATION
Authors: SHI X. , HU Y. H. , HU L.
Published: July 2002

Tetrahedral Amorphous Carbon (ta-C) thin film by using Filtered Cathodic Vacuum Arc (FCVA) technique has proven to be wear-resistive and corrosion resistant for a wide range of electrical, optical, and mechanical applications. Many investigations have shown that the ta-C film prepared by the FCVA technique can provide a superior ultra thin overcoat for the sliders and media compared to ECR-CVD and IBD coating technology. The ta-C film excels in terms of the film density, hardness, surface roughness and corrosion resistance. Nanofilm Technology International (NTI) has successfully developed and commercialized the FCVA coating system (FS series) for the slider overcoat application, which provides a good quality film with a high hardness (~50 GPa), low stress (2~3 GPa), low macro-particle density (~1/cm2 for particles > 0.3 μm), good uniformity (< 4%$ in 8 inch coating area) and high production repeatability (< 5%).
CRYSTALLINE CARBON NITRIDE FILMS GROWN BY MICROWAVE PLASMA CHEMICAL VAPOR DEPOSITION
Authors: ZHENG W. T. , WANG X. , DING T. , LI X. T. , FEI W. D. , SAKAMOTO Y. , KAINUMA K. , WATANABE H. , TAKAYA M.
Published: July 2002

The carbon nitride films were deposited on single crystalline Si(001) and polycrystalline diamond substrates using microwave plasma chemical vapor deposition (MPCVD) with CH4+N2 as well as CH4+NH3 mixtures as the reactive gas source, respectively. Different CH4/N2 and CH4/NH3 gas ratios were tested. The results showed that carbon nitride films with different nitrogen content could more readily be obtained using a mixture of CH4/N2 rather than CH4/NH3. The films grown by different CH4/N2 ratios showed different morphology, which was revealed by scanning electron microscopy (SEM). The crystalline carbon nitride films containing silicon were realized using a CH4:N2 = 1:100 ratio. X-ray photoelectron spectroscopy (XPS), Auger electron microscopy (AES), Raman spectroscopy, and X-ray diffraction were used to characterize the composition and chemical bonding of the deposited films.
NEW RESULTS FOR SUSCEPTIBILITIES IN PLANAR ISING MODELS
Authors: AU-YANG HELEN , PERK JACQUES H.H.
Published: July 2002

We briefly review recent progress on calculating susceptibilities in planar Ising models.
EXPLORING THE QUANTUM WORLD OF COMPLEX STATES
Authors: ORTIZ G. , JONES M. D.
Published: July 2002

Solving the fundamental microscopic equations of interacting quantum particles is a goal of many-body physicists. Statistical methods reduce the complexity of the problem by sampling phase space selectively using random-walks and real states. Many interesting physical phenomena (e.g., electrons in external magnetic fields) involve systems whose state functions are inherently complex-valued. The Fixed-Phase method is a stochastic approach to deal with such problems. Its key ingredient is a trial phase that plays the role of gauge function in the transformation that maps the original fermion (or boson) problem to a boson problem for the modulus of the state function. The Released-Phase method relaxes that constraint and allows us to obtain, in principle, the "exact" properties, although it is subjected to the infamous "phase problem." In our tour of the (complex) Quantum World, we will show how these methods have been successfully applied to a wide variety of physical phenomena ranging from quantum Hall topological fluids and Wigner crystals to the study of the core structure of vortices in superfluid 4 He and atomic systems in superstrong magnetic fields found in astrophysical settings.
In-Situ High Temperature Neutron Diffraction Study of Bi,Pb(2223) Phase Formation in Ag-Sheathed Monofilamentary Tapes
Authors: Giannini E. , Bellingeri E. , Passerini R. , Flükiger R.
Published: July 2002

High temperature neutron diffraction measurements were performed on Bi(2223)/Ag-sheathed monofilamentary tapes at the ILL high-flux reactor in Grenoble. Reactions leading to the conversion from Bi(2212) to Bi,Pb(2223), as well as other transformations involving secondary phases, were directly observed during the reaction heat treatment. The heating ramp and annealing conditions were exactly the same as those used for standard high-performance tapes processing. A quantitative analysis was carried out by means of a full-pattern profile refinement technique: up to 7 phases were simultaneously detected and successfully refined. An increase of the Bi(2212) phase during a slow cooling was found not to be related to a decomposition of Bi,Pb(2223), which remained stable during cooling. The role of secondary cuprates, in particular (Ca,Sr) 14 Cu 24 O 41, was investigated. Since neutron diffraction allows for an absolute measurement of the weight of crystalline matter inside the sample, it was possible to measure the total crystalline matter amount as a function of temperature and time during processing. Evidence of partial melting at high temperature was found strongly supporting the Bi,Pb(2223) formation via a nucleation-and-growth mechanism at the early stage of the process.
Three Terminal HTc Vortex Flow Transistors: Optimisation of the Device Geometry Employing Bicrystal Grain-Boundary Josephson Junctions
Authors: Granata V. , Davidson B. A. , Sarnelli E. , Pagano S.
Published: July 2002

We have numerically studied the static and dynamic behavior of a three terminal vortex-flow transistor based on a parallel array of Josephson junctions. We explicitly show advantages and disadvantages for different device geometric configurations, systematically changing the symmetry of the bias-current distribution. Using parameters typical of high-temperature superconducting junctions at 77K, we have analysed for each configuration the dependence of the critical current on the control current, and the voltage-current curves. We have calculated gain and transresistance for different bias conditions, and explained the numerical results in terms of the vortex dynamics in the array. This study allows us to establish limits for the operating regime of these devices when used as high-frequency amplifiers.
Light Shutter Using ER Fluid Thin Films Dispersing ITO and ZnO Particles
Authors: Yamaguchi Kunihiko , Jeyadevan Balachandran , Fujita Toyohisa , Nishihara Akira
Published: July 2002

We have studied optical properties of alkylnaphthalene suspensions dispersing semiconductor ultra fine ITO (Indium Tin Oxide) particles or insulator ZnO particles to apply them to light shutter. The suspensions behave like ER fluids which show an increase in viscosity under an electric field. When the ITO or ZnO dispersions are sandwiched between glass plates coated by a transparent conducting film, the fluid films transmit visible light. Application of the electric field in the direction of the light beam to the fluid film dispersing ITO particles shows an increase in the transmittance for near infrared rays, whereas the transmittance in visible light region decreases with the electric field. On the other hand, the transmittance through the fluid film dispersing ZnO particles decreases in the wavelength region from visible light to near infrared rays with the electric field. These phenomena depend on the cluster size under the electric field and the solid concentration of the suspensions. We can explain the results in terms of light scattering due to ITO or ZnO clusters formed in the electric field and optical absorption due to free carriers in ITO particles.
COUPLING OF THE ORTHORHOMBIC DISTORTION TO THE DEPRESSION OF THE Tc'S DUE TO Zn2+ DOPING IN THE "RE-123" HTSC'S: A (d+s)-WAVE PICTURE
Authors: TANG I. M. , CHAROENTHAI N. , THONGRUANG R.
Published: July 2002

The depressions of the T c 's of the "123" REBa 2 Cu 3 O 7 HTSC's due to the substitution of Zn 2+ ions into the Cu(2) layer are studied. The orthorhombic distortion which occurs in the "123" ceramics is assumed to induce a modification to the spin-fluctuation (SF) mediated pairing interaction which inturn causes the order parameters of these HTSC's to be of mixed (d+s)-wave symmetry. It is shown that part of the rapid depression of the T c 's caused by Zn 2+ substitution into the CuO 2 is due to a reduction of the SF-mediated pairing interaction. The differences in the rates of suppression of T c due to Zn 2+ doping in the different "RE-123" HTSC's are shown to be due to the changes in the orthorhombicity which depend on the size of the rare earth ions.
SPIN CONFIGURATIONS OF π ELECTRONS AND DIMERIZATION IN QUASI-ONE-DIMENSIONAL ORGANIC BIPARTITE LOZENGE CHAINS
Authors: DUAN Y. F. , YAO K. L. , YI L.
Published: July 2002

Based on a theoretical model proposed for an organic bipartite lozenge ferrimagnetic chain, the spin configuration of π electrons and the dimerization are investigated. With the Hartree–Fock approximation, the strong electron–phonon coupling and the electron–electron interaction in the one-dimensional system are taken into account self-consistently. It is shown that around the middle of the chain appears a π electron spin polarization cloud with alternation of sign and amplitude of the spin density extending over a certain distance, which extends all over the chain with no decay when the e–e interaction is larger than a critical value. In the stable ferrimagnetic state, the antiferromagnetic exchange interaction between electrons at site A and site B along the chain will become very strong, and almost zero dimerization happens for the chain.
SOFTWARE TOOLKIT FOR TEACHING IMAGE PROCESSING
Authors: POWELL MARK W. , GOLDGOF DMITRY
Published: July 2002

We introduce a software framework called the Java Vision Toolkit (JVT) for teaching image processing and computer vision. The toolkit provides over 50 image operations and presents them to the user in a GUI that can render grayscale, color and 3D range images. The software is written in Java, enabling it to be integrated into HTML documents and interactive course materials. The framework is designed for extensibility using a source code template that supports the implementation of any new operation with a minimal amount of supporting code. For students, this framework encapsulates the GUI, file I/O and other trivial programming details and allows them the maximum amount of time to spend on understanding computer vision. We compare the JVT with other computer vision software frameworks that are used for teaching and research. We also discuss the use of the JVT in an undergraduate image processing course at the University of South Florida.
SPHERICAL CELLULAR NONLINEAR NETWORKS
Authors: YANG TAO , CROUNSE KENNETH R. , CHUA LEON O.
Published: July 2002

We present the structures and behaviors of cellular nonlinear networks (CNN) on spheres (spherical CNN for short). Although the cells in a spherical CNN can have any number of neighbors, in this paper we study the cases where each cell has only three neighbors. We present the simulation results of symmetric and asymmetric spherical CNNs. In our simulations, we use a Bucky-ball spherical CNN structure with 60 cells and an irregular spherical CNN structure with 100 cells. Since a spherical CNN has no boundary, we use an asymmetric spherical CNN to show how information propagates on spheres via local couplings. We also show that if a spherical CNN is locally active then different patterns can be found in its stable output.
WAVELET-BASED IN-BAND DENOISING TECHNIQUE FOR CHAOTIC SEQUENCES
Authors: CONSTANTINE WILLIAM L. B. , REINHALL PER G.
Published: July 2002

A novel wavelet-based denoising technique (MODRA) is introduced and shown to be an effective means of denoising in-band contaminated chaotic sequences. MODRA is compared to existing WaveShrink methods and shown to be a more effective denoising technique based on a mean-squared-error statistic for simulated contaminations. For each case, an estimate of the correlation dimension D2 is calculated to quantify the results. As an integral part of MODRA, a best basis cost functional for the maximum overlap discrete wavelet packet transform using Shannon entropy is also introduced.
A FAMILY OF INTEGER-VALUED COMPLETE INVARIANTS OF ORIENTED KNOT TYPES
Authors: NAKAGAWA YOSHIYUKI
Published: July 2002

By using Ghrist's theorem that universal templates exist, we define a family of integer-valued invariants {νn} of oriented knot types, each of which is complete. We give (1) an estimation of νn(K) from below in terms of the genus of K and (2) an estimation of νn(K) from above in terms of the word length of a braid presentation of K. To do this, we introduce a yet another invariant λn(K) and give an estimation of λn(K). Moreover, we show that the estimation of λn(K) from below is best possible, by explicitly determining the invariant νn(K) for some knots.
STATIONARY AXIALLY SYMMETRIC NON-ABELIAN ROTATING COSMIC STRINGS
Authors: SLAGTER REINOUD JAN
Published: July 2002

We investigated the SU(2) Einstein–Yang–Mills system on a stationary axially symmetric nondiagonal spacetime. The equations are numerically solved. There is evidence for the existence of a regular solution with nonvanishing angular momentum, and finite energy density for all r. The behavior of the solution depends critical on the ratio of the Planck scale M pl and Yang–Mills couplings constant g, i.e., [Formula: see text]. Further, the asymptotic behavior of the solution is strongly affected by the boundary conditions of one of the YM components at z = 0. It is conjectured that the singular behavior of the metric components at finite distance of the core is related to the gravitational instability found in the self-gravitating flat-space non-Abelian monopole, the Einstein–Skyrme model and Einstein–Yang–Mills–Higgs model
THE WAVELET TRANSFORM IN THE SOLUTION TO THE INVERSE FRACTAL PROBLEM
Authors: STRUZIK ZBIGNIEW R.
Published: July 2002

The inverse fractal problem for self-affine functions in R 2 is solved by means of testing the invariance of the wavelet transform of the function. The wavelet maxima bifurcation representation used is derived from the continuous wavelet decomposition and possesses translational and scale invariance necessary to reveal the invariance of the self-affine fractal. Algorithms are presented which give satisfactory results for the self-affine fractal and which potentially can be applied to a variety of fractal types in order to solve the related inverse fractal problem.
SOFT TISSUE COMPLICATIONS FOLLOWING KIRSCHNER WIRE FIXATION FOR FUSION OF BASAL JOINT ARTHRITIS
Authors: Koh W. L. , Lim B. H.
Published: July 2002

Basal joint arthritis is a common hand condition presenting with pain and swelling, often requiring surgical treatment in the late stages. Surgical options include arthrodesis, excision arthroplasty, implant arthroplasty and ligament reconstruction, and tendon interposition arthroplasty.

A patient with bilateral basal joint arthritis underwent K-wire arthrodesis of the left basal joint. Subsequently, she developed complications due to impingement of the K-wire on the median nerve, superficial radial nerve, and flexor tendons of the index finger. The diagnosis was made three years post-operatively and she then underwent reconstructive surgery. Eventually she recovered with good movement and sensation of the affected digits.

Although K-wire arthrodesis of basal joint is a simple and effective procedure used primarily in treatment of arthritis, this case highlights the importance of appreciating surgical anatomy and post-operative clinical features and investigations.
A DISTRIBUTED DYNAMIC HEURISTIC FOR DELAY-CONSTRAINED LEAST-COST MULTICAST ROUTING
Authors: Wang Zhengying , Shi Bingxin , Liu Wei
Published: July 2002

Many new distributed multimedia applications involve dynamic multiple participants, have stringent end-to-end delay requirement and consume large amount of network resources. In this paper, we propose a new distributed dynamic delay-constrained least-cost multicast routing algorithm (DDDCLCMR) to support these applications. DDDCLCMR scales well because the source of the multicast tree needs only limited computation or may even not be involved in the route computation. When group membership changes, the existing multicast tree is perturbed as little as possible. Simulation results show that DDDCLCMR performs very good in terms of delay and cost for both, static and dynamic multicast groups, when compared to the best multicast algorithms known.
EVALUATION OF SEISMIC DEMANDS IN A CONTINUOUS BRIDGE
Authors: LOH CHIN-HSIUNG , WAN SHIUAN , CHANG YI-WEN
Published: July 2002

This paper examines the dynamic behavior of a highway RC-bridge subjected to both near-fault and far-field ground motions. The bridge consists of a hinge supported continuous girder with six concrete piers and the bridge is designed according to the Taiwan seismic design code. To investigate the hysteretic behavior of the bridge piers, cyclic loading tests were carried out at the National Center for Research on Earthquake Engineering (NCREE). The Chi-Chi earthquake ground motion record was adopted as the near-fault earthquake characteristics whereas another earthquake record was selected for the far-field earthquake characteristics. The ductility demands and base shear demands due to the near-fault and the far-field earthquake ground motions are compared and conclusions drawn from the study. The stipulation of code limitations and the present calculated demands are discussed.
THE USE OF FINITE ELEMENT METHOD TO ADDRESS PROXIMAL MIGRATION OF FEMORAL NECK FRACTURE FIXATION DEVICES IN THE ELDERLY
Authors: ATKINSON PATRICK , TAVAKOLI MASSOUD , BATES CONNOR , KIM SANG , PRUCHER STEVE , LARSON BRYAN , MARTIN SIDNEY
Published: July 2002

Falls among the elderly are a common occurrence and the incidence rate is increasing with our aging population. In such a population, a fall may precipitate a femoral neck fracture which may be treated by any one of a variety of femoral screw/plate mechanisms. Unfortunately, such mechanisms can fail in service as the device migrates proximally eventually requiring a secondary and more invasive surgery. In the current study we propose a new design to address this failure mechanism and we use a simple finite element model to study a modification to the current design.
Automated assistance for program restructuring
Authors: Griswold William G. , Notkin David
Published: July 2002

Maintenance tends to degrade the structure of software, ultimately making maintenance more costly. At times, then, it is worthwhile to manipulate the structure of a system to make changes easier. However, manual restructuring is an error-prone and expensive activity. By separating structural manipulations from other maintenance activities, the semantics of a system can be held constant by a tool, assuring that no errors are introduced by restructuring. To allow the maintenance team to focus on the aspects of restructuring and maintenance requiring human judgment, a transformation-based tool can be provided—based on a model that exploits preserving data flow dependence and control flow dependence—to automate the repetitive, error-prone, and computationally demanding aspects of restructuring. A set of automatable transformations is introduced; their impact on structure is described, and their usefulness is demonstrated in examples. A model to aid building meaning-preserving restructuring transformations is described, and its realization in a functioning prototype tool for restructuring Scheme programs is discussed.
Creating products customers demand
Authors: Hutchings Anthony F. , Knox Steve T.
Published: July 2002

This article presents a re-engineering case study of the product requirements definition process at Digital Equipment Corporation. Based on cross-functional teams working in direct partnership with customers, the re-engineered process was designed to ensure customer satisfaction and business readiness before a line of code is written, an electronic circuit designed, or a service defined.
Complexity of Makanin's algorithm
Authors: Kościelski Antoni , Pacholski Leszek
Published: July 2002

The exponent of periodicity is an important factor in estimates of complexity of word-unification algorithms. We prove that the exponent of periodicity of a minimal solution of a word equation is of order 2
1.07d
, where
d
is the length of the equation. We also give a lower bound 2
0.29d
so our upper bound is almost optimal and exponentially better than the original bound

(6d)
22d4
+ 2

. Consequently, our result implies an exponential improvement of known upper bounds on complexity of word-unification algorithms.
Efficient decomposition of polygons into L-shapes with application to VLSI layouts
Authors: Lopez Mario A. , Mehta Dinesh P.
Published: July 2002

We present two practical algorithms for partitioning circuit components represented by rectilinear polygons so that they can be stored using the L-shaped corner stitching data structure; that is, our algorithms decompose a simple polygon into a set of nonoverlapping L-shapes and rectangles by using horizontal cuts only. The more general of our algorithms computes and optimal configuration for a wide variety of optimization functions, whereas the other computes a minimum configuration of rectangles and L-shapes. Both algorithms run in
O
(
n
+
h
log
h
time, where
n
is the number of vertices in the polygon and
h
is the number of H-pairs. Because for VLSI data
h
is small, in practice these algorithms are linear in
n
. Experimental results on actual VLSI data compare our algorithms and demonstrate the gains in performance for corner stitching (as measured by different objective functions) obtained by using them instead of more traditional rectangular partitioning algorithms.
Fourier Analysis of Uniform Random Number Generators
Authors: Coveyou R. R. , Macpherson R. D.
Published: July 2002

A method of analysis of uniform random number generators is developed, applicable to almost all practical methods of generation. The method is that of Fourier analysis of the output sequences of such generators. With this tool it is possible to understand and predict relevant statistical properties of such generators and compare and evaluate such methods. Many such analyses and comparisons have been carried out. The performance of these methods as implemented on differing computers is also studied. The main practical conclusions of the study are: (a) Such a priori analysis and prediction of statistical behavior of uniform random number generators is feasible. (b) The commonly used multiplicative congruence method of generation is satisfactory with careful choice of the multiplier for computers with an adequate (≥ ∼ 35-bit) word length. (c) Further work may be necessary on generators to be used on machines of shorter word length.
An Algorithm for Generating Stable Feedback Shift Registers of Order
n
Authors: Mowle Frederic J.
Published: July 2002

It is shown in this paper that the stable feedback shift registers, when classified according to Hamming weight (the number of fundamental product terms in expanded sum of products form), are binomially distributed, i.e., are (2

n

-
n
- 1
w
) stable feedback shift registers of order
n
with Hamming weight equal to
w
. Using this relationship, a recursive algorithm is established which will generate all stable feedback shift registers of order
n
. Formulas are also given for determining the number of stable feedback shift registers which have
j
+ 1 starting states and
j
+ 1 branch states, 0 ≤
j
≤ 2

n
-1

- 1.
Weak alternating automata are not that weak
Authors: Kupferman Orna , Vardi Moshe Y.
Published: July 2002

Automata on infinite words are used for specification and verification of nonterminating programs. Different types of automata induce different levels of expressive power, of succinctness, and of complexity.
Alternating automata
have both existential and universal branching modes and are particularly suitable for specification of programs. In a
weak alternating automata
the state space is partitioned into partially ordered sets, and the automaton can proceed from a certain set only to smaller sets. Reasoning about weak alternating automata is easier than reasoning about alternating automata with no restricted structure. Known translations of alternating automata to weak alternating automata involve determinization, and therefore involve a double-exponential blow-up. In this paper we describe a quadratic translation, which circumvents the need for determinization, of Büchi and co-Büchi alternating automata to weak alternating automata. Beyond the independent interest of such a translation, it gives rise to a simple complementation algorithm for nondeterministic Büchi automata.
Integrated concurrency control and recovery mechanisms: design and performance evaluation
Authors: Agrawal Rakesh , Dewitt David J.
Published: July 2002

In spite of the wide variety of concurrency control and recovery mechanisms proposed during the past decade, the behavior and the performance of various concurrency control and recovery mechanisms remain largely not well understood. In addition, although concurrency control and recovery mechanisms are intimately related, the interaction between them has not been adequately explored. In this paper, we take a unified view of the problems associated with concurrency control and recovery for transaction-oriented multiuser centralized database management systems, and we present several integrated mechanisms. We then develop analytical models to study the behavior and compare the performance of these integrated mechanisms, and we present the results of our performance evaluation.
Design complexity measurement and testing
Authors: McCabe Thomas J. , Butler Charles W.
Published: July 2002

System designers can quantify the complexity of a software design by using a trio of finely tuned design metrics.