bluuebunny/crossref_metadata_2025 huggingface dataset:
A pathwise solution for nonlinear parabolic equations with stochastic perturbations
Authors: Iftimie Bogdan , Varsan Constantin
Published: August 2006

We analyse here a semilinear stochastic partial differential equation of parabolic type where the diffusion vector fields are depending on both the unknown function and its gradient ∂
xu with respect to the state variable, ∈ ℝn. A local solution is constructed by reducing the original equation to a nonlinear parabolic one without stochastic perturbations and it is based on a finite dimensional Lie algebra generated by the given diffusion vector fields.
The prime and maximal spectra and the reticulation of BL-algebras
Authors: Leuštean Laurenťiu
Published: August 2006

In this paper we study the prime and maximal spectra of a BL-algebra, proving that the prime spectrum is a compact T
0 topological space and that the maximal spectrum is a compact Hausdorff topological space. We also define and study the reticulation of a BL-algebra.
Combined polymerization catalysis of nickel complex and zirconocene for branched polyethylene
Authors: Cui Yong , Shao Changxing , Sun Wen-Hua
Published: August 2006

The polymerization behavior of 2-(2′-pyridyl) quinoxaline nickel dibromide/Cp2ZrCl2/MAO system was investigated in three ways: the Ni catalyst was added first, followed by addition of Zr catalyst (method I); the Ni and Zr catalysts were added simultaneously (method II); and the Zr catalyst was added first, followed by addition of Ni catalyst (method III). Results of GC-MS, GPC,13C NMR and DSC investigations indicated that the properties of resulting polyethylene were greatly varied by changing feeding orders of the two catalysts. Decreasing Ni/Zr molar ratio or increasing polymerization temperature gave corresponding polyethylenes with less branches and higher melting point. Compared to the procedure using Cp2ZrCl2 catalyst only, the activity of Zr catalyst in those combined system decreased because of the competition of ethylene between the [Ni−C] and [Zr−C] active centers. In addition, other zirconocenes were also employed as copolymerization catalysts in the combined system with nickel complex. compared to Cp2ZrCl2 case, the ethyl-bridged Zr catalyst performed better for polymerization of ethylene while the Si-bridged Zr catalyst showed better copolymerization ability.
Thermal and kinetic characteristics in non-isothermal conditions of some aromatic copolyethers containing an octomethylenic spacer
Authors: Prajinaru Mihaela , Hurduc Natalia , Alazaroaie Silvia , Catanescu Otilia , Hurduc Nicolae
Published: August 2006

The paper presents a study of the thermal properties of some aromatic polyethers obtained by phase trasfer catalysis technique. The polymes were synthesized starting from 1,8-dichloro-octane and various bisphenols: 4,4′-dihydroxyazobenzene, 4,4′-dihydroxydiphenyl, bisphenol A and 2,7-dihydroxynaphthalene. Molecular simulations were performed in order to obtain supplementary information concerning the chain conformation and inter-chain interactions. The presence of azobenzenic moieties induces high phase transition values, situated near the thermal stability limit. Therefore, the thermogravimetrical study of these polymers is very important for establishing the temperature limits for DSC and optical microscopy studies. All the polymers present a good thermal stability situated above the isotropization values. In these circumstances no special precautions are necessary for the characterization methods of the liquid crystalline behavior. The kinetic characteristics suggest a similar degradation mechanism by successive reactions. The inter-chain interactions do not influence the thermostability of the samples if the polar surface of the polymer is situated below a certain value.
Methods for the calculation of occupied volumes in glassy polymers: The lattice integration and the monte carlo methods
Authors: Rozhkov E. , Schukin B. , Ronova I.
Published: August 2006

A new model for characterizing the free volume of a glassy polymer—gas systems is proposed. An improved method for the calculation of occupied volume per monomer unit was developed within the limits of this model. The model assumptions, error estimates and algorithm efficiencies are described. Using the example of polyvinyltrimethylsilane, it is shown that linear dependences of logarithms of the diffusion and the permeability coefficients on specific accessible volume for inert gases exist.
Thermally induced oxidative trimerization of benzimidazole by copper(II) chloride in the solid state
Authors: Bhattacharya Rahul , Ray Sibdas , Ray Jayanta , Ghosh Ashutosh
Published: August 2006

Benzimidazolium trichlorocuprate(II) undergoes a redox reaction in the solid state at elevated temperature (∼240°C) to produce the cyclic trimer of benzimidazole and cuprous chloride. The trimer has been characterized by IR, NMR, and Mass spectroscopy. It has also been synthesized in lower yield by heating the mixtures of CuCl2 and benzimidazole in different ratios or heating other compounds of CuCl2 and benzimidazole. The absorption, emission, and excitation spectra of the trimer in two different solvents (TFA and DMSO) and a comparison of these results with those of benzimidazole are presented here.
Hydrazyl, Nitronyl-, and imino-nitroxides: Synthesis, properties and reaction with nitric oxide and nitrogen dioxide
Authors: Constantinescu Titus , Ionita Petre , Chiorescu Ion , Ionita Gabriela
Published: August 2006

Ten novel and stable free radicals of nitronyl-, imino-nitroxide and hydrazyl type compounds were synthesized and their physico-chemical properties investigated. UV-Vis and ESR spectroscopic data, as well as the lipophilicities and specific hydrophobic areas of the compounds are compiled. The reaction of these radical compounds with nitric oxide and nitrogen dioxide was also investigated. The radicals synthesized, show selectivity in their reaction with these nitric oxides, depending on their structure (nitronyl-nitroxide radicals react with NO, while hydrazyl radicals react with NO2). The processes are easily monitored by UV-Vis or ESR spectroscopy.
Synthesis and crystal structure of 1-ethyl-3-(phenyl)-1,2,3-triazolium percholorate
Authors: Doreswamy Beeranahally , Mahendra Madegowda , Anandalwar Sridhar , Prasad Javaregowda , Mantelingu Kempegowda ,   Basappa, Rangappa Kanchugarakoppal
Published: August 2006

The isolation of stable carbenes of the Arduengo (1a) and Wanzlick (2a) type has prompted us to look for stable nitrenium ions of the related structural type 1-ethyl-3-(phenyl)-1,2,3-triazolium perchlorate (6+). The title compound C10H14Cl N3O4 was isolated and structure was investigated by X-ray crystallography. It crystallizes in the monoclinic space group P21/c with cell parameters a=6.697(4) Å, b=9.724(9) Å, c=19.844(2) Å and Z=4. The final residual factor is R1=0.0471 for 1545 reflections with I>2σ(I). The structure exhibits intermolecular hydrogen bonds.
Transverse electron focusing as a way of studying phonon kinetics. Turbulence of phonon flow
Authors: Tsoi Valerii
Published: August 2006

Novel techniques have been created for studying phonon kinetics. A supersonic conduction electron flux is used to produce a phonon flux. Transverse electron focusing (TEF) is applied for checking the electron gas affected by phonons. A turbulent regime of phonon flow-phonon flux step broadening-reveals itself as step broadening of non-equilibrium electron flux.
Influence of the sample orientation in Sn2P2S6 crystals on the hydrostatic piezoelectric coefficients
Authors: Panoŝ Stanislav , Panoŝová Dagmar
Published: August 2006

The influence of the sample orientation on the effective value of the hydrostatic piezoelectric coefficients dh(i) of Sn2P2S6 crystals has been studied. The hydrostatic piezoelectric coefficients dh(1) and d′h(3), were measured, dh(1)=(244±3) pC/N and d′h(3)=(92±1) pC/N. The hydrostatic piezoelectric coefficient d h(3) for orthogonal axis system was calculated to be dh(3)=(87±2) pC/N. The, optimal orientation of the sample has been found as (Xy l)−20°-cut. Maximal value of the effective hydrostatic piezoelectric coefficient d h(1) equals 260 pC/N. Double rotated samples were also studied. The orientation of the samples insensitive to the pressure has been found. The theoretical mean value of hydrostatic piezoelectric coefficient (d h)mean corresponding to randomly oriented Sn2P2S6 grains in a poled composite has been calculated to be (d h)mean=136 pC/N.
The scattering of light on sound waves in the hypersonic range of frequencies the directional sensitivity of Brillouin light scattering
Authors: Błachowicz Tomasz
Published: August 2006

Brillouin spectroscopy of acoustic phonons in transparent crystals and nontransparent metallic Co/Cu superlattices is reviewed. The method presents a directional sensitivity of the experiment. This feature is useful in elastic constants measurements in crystals and analysis of in-plane anisotropies of hyper-sound and spin waves in superlattices. Results for the LiTaO3, LiNbO3, LiNbO3:Cu, SLGO, SLAO crystals are provided. Spin wave results for the Co/Cu superlattices are presented.
Simple analytic solution of fireball hydrodynamics
Authors: Csörgő Tamás
Published: August 2006

A new family of simple analytic solutions of hydrodynamics is found for slowly expanding, rotationally symmetric fireballs assuming an ideal gas equation of state. The temperature profile is position-independent only in the collisionless gas limit. The Zimányi-Bondorf-Garpman solution and the Buda-Lund parameterization of expanding hydrodynamic particle sources are recovered as special cases. The results are applied to predict new features of proton correlations and spectra for 1.93 AGeV Ni+Ni collisions.
Runaway of electrons in dense gases and mechanism of generation of high-power subnanosecond beams
Authors: Tkachev Alexey , Yakovlenko Sergei
Published: August 2006

New understanding of mechanism of the runaway electrons beam generation in gases is presented. It is shown that the Townsend mechanism of the avalanche electron multiplication is valid even for the strong electric fields when the electron ionization friction on gas may be neglected. A non-local criterion for a runaway electron generation is proposed. This criterion results in the universal two-valued dependence of critical voltage U cr on pd for a certain gas (p is a pressure, d is an interelectrode distance). This dependence subdivides a plane (U cr, pd) onto the area of the efficient electron multiplication and the area where the electrons leave the gas gap without multiplication. On the basis of this dependence analogs of Paschen’s curves are constructed, which contain an additional new upper branch. This brunch demarcates the area of discharge and the area of e-beam.

The mechanism of the formation of the recently created atomospheric pressure subnanosecond e-beams is discussed. It is shown that the beam of the runaway electrons is formed at an instant when the plasma of the discharge gap approaches to the runaway electrons is formed at an instant when the plasma of the discharge gap approaches to the anode. In this case a basic pulse of the electron beam is formed according to the non-local criterion of the runaway electrons generation.

The role of the discharge gap preionization by the fast electrons, emitted from the plasma non-uniformities on the cathode, as well as a propagation of an electron multiplication wave from cathode to anode in a dense gas are considered.
Multiscale semicontinuous thin film descriptors
Authors: Boldyš Jiří , Hrach Rudolf
Published: August 2006

In experimental thin film physics, there is a demand to characterize a growing thin film or the thin film resulting from an experiment. While methods for discontinuous, island-like thin films have been developed, there is a lack of results directly applicable to semicontinuous thin film description. In this contribution, a unique combination of image processing methods is collected and further developed, which results in a novel set of semicontinuous thin film descriptors. In particular, the shape of the thin film contours and the thin film image intensity profiles are analyzed in a multiscale manner. The descriptiveness of the proposed features is demonstrated on a few thin film photographs from real experiments. This work establishes a basis for further measurement, description, simulation or other processing in the physics of semicontinuous thin films, using any direct imaging modality.
Hyperfine structure operator in the tensorial form of second quantization
Authors: Gaigalas Gediminas , Rudzikas Zenonas , Scharf Oliver
Published: August 2006

The general tensorial form of the hyperfine interaction operator in the formalism of second quantization is presented. Both diagonal and off-diagnonal matrix elements of the above-mentioned operator are found using an approach based on a combination of second quantization in the coupled tensorial form, angular momentum theory in three spaces (orbital, spin and quasispin) and a generalised graphical technique. This methodology allows us to account for correlation effects efficiently and, therefore, to study the hyperfine interactions in complex many-electron atoms, those with openf-shells included, in a practical manner. All this will lead us to design an efficient program for large scale calculations of hyperfine structure and isotope shift.
Studies of the soluble part of oxidised coals
Authors: Pietrzak Robert , Kozłowski Mieczysław , Wachowska Helena , Yperman Jan
Published: August 2006

Soluble products obtained from the oxidation of four types of coal, each characterised by different degree of coalification and different degree of sulphur content, are studied. The coals are oxidised with peracetic acid (PAA) and nitric acid. Analyses are performed by Atmospheric Pressure-Temperature Programmed Reduction (AP-TPR) and Fourier Transform Infrared Spectroscopy (FTIR). The soluble products contain much more sulphur than the insoluble products of oxidation. The products obtained from the reaction with HNO3 contain higher amounts of inorganic sulphur compounds, while those obtained from the reaction with PAA are characterised by an increased content of organic sulphur species.
Photo- and thermoinduced ring opening reaction of 2[(1,3,3-trimethylindoline-2(1H)-yliden)propen-1-yl]-3,3-dimethylindolino[1,2-b]-oxazolidine in polymer films
Authors: Petkov I. , Charra F. , Nunzi J , Deligeorgiev T.
Published: August 2006

The influence of UV light and temperature on poly(methylmethacrylate) (PMMA) and poly(vinylchloride) (PVC) films, doped with 2[(1,3,3-trimethylindoline-2(1H)-yliden)propen-1-yl]-3,3-dimethylindolino[1,2-b]-oxazolidine has been investigated. The radiation-induced colour was analyzed spectrophotometrically at the maximum of the absorption peak at 560 nm. The effect of the temperature on unirradiated and irradiated films was studied. The results demonstrate a strong photochromic and a weak thermochromic behaviour of the PMMA and PVC films. The relationship of photocolouration-thermal decolouration is discussed based on the spectral results reported here.
Determination of selenium in infant foods using electrothermal atomic absorption spectrometry with direct slurry sample introduction
Authors: Baralkiewicz Danuta , El-Sayed Usama , Filipiak Marian , Gramowska Hanka , Mleczek Miroslaw
Published: August 2006

Slurry sampling electrothermal atomic absorption (SS ETAAS) was applied to the development of a sensitive and precise method for selenium determination in infant foods without sample pretreatment. Suspensions prepared in a medium containing 0.1% Triton X-100, 0.5 or 5% v/v concentrated HNO3 were directly introduced into the furnace. The accuracy of the procedure was confirmed by analysis of a standard reference material and comparison with hydride generation atomic absorption spectrometric (HGAAS) procedure. The characteristic mass is 44 pg and detection limit 0.43 μg·l−1.
Intermicellar material exchange in reverse micelles formed by ionic AOT and nonionic Igepal surfactants studied by means of pulse radiolysis. Influence of the temperature
Authors: Gębicki Jerzy
Published: August 2006

The recombination of thiocyanate anion radicals, (SCN)2−, formed pulse radiolytically within the water pools of reverse micelles stabilized with anionic AOT and nonionic Igepal surfactants, was proved as an indicator reaction to study intermicellar exchange. It was found that the exchange process is slower inIgepal than in AOT reverse micelles with the same water to surfactant ratio. The apparent activation enthalpy and entropy of the exchange process were determined in different alkanes. For the AOT and Igepal reverse micelles the activation parameters increase with the droplet size, but for the AOT systems they do not significantly change with the increase of droplet concentration. For non-percolated systems the activation parameters for Igepal reverse micelles approach those for AOT reverse micelles. This result supports existing suggestions that the mechanism of intermicellar exchange does not differ in principle between reverse micelles stabilized with ionic and nonionic surfactants.
Comparative study of structural stability in [NH4−n
(CH3)n]2HgCl4 and in related compounds
Authors: Amami M. , Salah A.
Published: August 2006

The structural instability of the [NH4−n
(CH3)n]2HgCl4 group has been investigated. Consideration of different crystals of this family shows that the H-bonds, obviously, hinder the appearance of incommensurate modulation. The dependence of phase transition sequence on the sizes of cation and anion may be obtained only for crystals with simple cation. The appearance of H-bonds complicates the situation and, leads to gradual disappearance of IC phase in the A2BX4 family.
Analysis of numerical limits in 2-D simulations of a ferromagnetic/antiferromagnetic interface using the random field Ising model
Authors: Błachowicz Tomasz
Published: August 2006

This paper explains the Random Field Ising Model simulations of a two-dimensional ferromagnetic/antiferromagnetic interface, influenced by the exchange-bias interaction. Exchange-biased shifts, coercivity fields, the number of unreversed spins as well as the numerical errors are provided. These were tested for different structure dimensions and boundary conditions in order to find limitations of the method. The algorithm developed is simple, very effective, and provides deeper insight into the nature of the exchange-bias phenomenon.
Theoretical calculations of the temperature dependence of the electrical and thermal conductivities of liquid gallium
Authors: El-Daher M. , Murphy Richard
Published: August 2006

The electrical and thermal resistivities of liquid gallium are calculated over a range of temperatures above the melting point using the solutions of the Boltzmann equation. The experimental x-ray structure factor of Waseda and the form factor derived using the Heine-Abarenkov model potential are used in these calculations. The ratio of the electrical and thermal conductivities is calculated and compared to experimental values and to the theoretical Lorenz number.
Some examples of negative feedback in the Earth climate system
Authors: Kärner Olavi
Published: August 2006

Temporal variability of daily time series for total solar irradiance at the top of the atmosphere, the Microwave Sounding Unit (MSU) based global, hemispherical and zonal average temperature for the lower troposphere and stratosphere together with 5 surface air temperature data, measured at various meteorological stations have been studied by means of the structure function. From the growth rate of the structure function in the time interval between 32 and 4096 days it follows that the variability of the series represents an anti-persistent (AP) behavior. This property in turn shows a domination of negative feedback in the physical system generating the lower tropospheric temperature variability. Distribution of the increments over various ranges and correlations between them are calculated in order to determine the quantitative characteristics describing temporal variability.
Classical simulations of magnetic structures for chromium clusters: Size effects
Authors: Proykova Ana , Stauffer Dietrich
Published: August 2006

Classical (Heisenberg) simulations show that the total magnetization of the lowest-energy states of clusters made of antiferromagnetically coupled chromium atoms is planar, rather than collinear, depending on the arrangement of the atoms. Although the model Hamiltonian is not restrictive, many cluster configurations of various numbers of atoms do not use all three directions for the spins. This result confirms the conclusion drawn from the local-spin DFT calculation by Kohl and Bertsch that clusters of N≤13 have non-collinear magnetic moments. The present simulations show non-collinear spin ordering also for bigger clusters, designed to be as spherical as possible following the bcc arrangement, when atoms interact both with the nearest and next-nearest neighbours. Depending on the signs of the coupling constants frustration appears. The advantage of the discrete model, despite the simplicity, is that very large clusters and magnetization at finite temperatures can be studied. This model predicts that clusters with specific numbers of atoms interacting only with the nearest neighbours have collinear spins as in the bulk. We also apply the model to simulate the destruction of the anti-ferromagnetic ordering by thermal fluctuations. This model shows no unique magnetization of mixed Fe
0.33
Cr
0.67, which is consistent with experimental observations.
Transverse magnetic scattering of two incident plane waves by a dielectric coated cylindrical reflector
Authors: Mushref Muhammad
Published: August 2006

Scattering characteristics of two plane waves are investigated for a circular cylinder covered by a dielectric substance. Fields are assumed to be transverse magnetic (TM) and represented in an exponential series form. The diffracted radiations are found by applying the boundary conditions to the wave functions. The wave transformation method and the orthogonality of the exponential functions are respectively employed to obtain an infinite series in the solution. Numerical results are evaluated by reducing the infinite series to a finite number of terms and comparing estimates with the single plane wave scattering situation.
On the size dependence of surface tension in the temperature range from melting point to critical point
Authors: Sdobnyakov Nickolay , Samsonov Vladimir
Published: August 2006

The problem of size dependence of surface tension was investigated in view of a more general problem of the applicability of Gibbs’ thermodynamics to nanosized objects. For the first time, the effective surface tension (coinciding with the specific excess free energy for an equimolecular dividing surface) was calculated within a wide temperature range, from the melting temperature to the critical point, using the thermodynamic perturbation theory. Calculations were carried out for Lennard-Jones and metallic nanosized droplets. It was found that the effective surface tension decreases both, with temperature and particle size.
An explanation of optical phenomena in non-crystalline semiconductors
Authors: Banik Ivan
Published: August 2006

Barrier model of a non-crystalline semiconductor is described in this article. The most important optical phenomena, which are typical for this group of materials, are explained on the base of this model. The model assumes that in non-crystalline semiconductors the potential barriers exist, which separate certain microscopic areas from each other, assuming barriers possess a parabolic profile. This conception explains the rise of exponential tails of optical absorption at the end of optical edge as well as electroabsorption, photoelectric conductivity, photoluminescence, and others. Using this model, many electric transport properties of non-crystalline semiconductors can be explained successfully.
Solutions of the Schrödinger equation for Dirac delta decorated linear potential
Authors: Uncu Haydar , Erkol Hakan , Demiralp Ersan , Beker Haluk
Published: August 2006

We have studied bound states of the Schrödinger equation for a linear potential together with any finite number (P) of Dirac delta functions. Forx

where 0f; 0x 1x 2x P , theσ i are arbitrary real numbers, and the potential is infinite forx
Tchebotaröv’s extremal problem
Authors: Tamrazov Promarz
Published: August 2006

We give the complete solution of the extremal problem posed by N.G. Tchebotaröv in 20th of the last century, and we establish explicit parametric formulae for the extremals.
Self-adjoint differential vector-operators and matrix Hilbert spaces I
Authors: Sokolov Maksim
Published: August 2006

In the current work a generalization of the famous Weyl-Kodaira inversion formulas for the case of self-adjoint differential vector-operators is proved. A formula for spectral resolutions over an analytical defining set of solutions is discussed. The article is the first part of the planned two-part survey on the structural spectral theory of self-adjoint differential vector-operators in matrix Hilbert spaces.
Integral representations of unbounded operators by infinitely smooth kernels
Authors: Novitskiî Igor
Published: August 2006

In this paper, we prove that every unbounded linear operator satisfying the Korotkov-Weidmann characterization is unitarily equivalent to an integral operator in L
2(R), with a bounded and infinitely smooth Carleman kernel. The established unitary equivalence is implemented by explicitly definable unitary operators.
The rate of convergence for spectra of GUE and LUE matrix ensembles
Authors: Götze Friedrich , Tikhomirov Alexander
Published: August 2006

We obtain optimal bounds of order O(n
−1) for the rate of convergence to the semicircle law and to the Marchenko-Pastur law for the expected spectral distribution functions of random matrices from the GUE and LUE, respectively.
The geometry of Kato Grassmannians
Authors: Bojarski Bogdan , Khimshiashvili Giorgi
Published: August 2006

We discuss Fredholm pairs of subspaces and associated Grassmannians in a Hilbert space. Relations between several existing definitions of Fredholm pairs are established as well as some basic geometric properties of the Kato Grassmannian. It is also shown that the so-called restricted Grassmannian can be endowed with a natural Fredholm structure making it into a Fredholm Hilbert manifold.
Covariance algebra of a partial dynamical system
Authors: Kosma Kwaśniewski Bartosz
Published: August 2006

A pair (X, α) is a partial dynamical system if X is a compact topological space and α: Δ→ X is a continuous mapping such that Δ is open. Additionally we assume here that Δ is closed and α(Δ) is open. Such systems arise naturally while dealing with commutative C
*-dynamical systems.

In this paper we construct and investigate a universal C
*-algebra C
*(X,α) which agrees with the partial crossed product [10] in the case α is injective, and with the crossed product by a monomorphism [22] in the case α is onto.

The main method here is to use the description of maximal ideal space of a coefficient algebra, cf. [16, 18], in order to construct a larger system,
$$(\tilde X,\tilde \alpha )$$
where
$$\tilde \alpha $$
is a partial homeomorphism. Hence one may apply in extenso the partial crossed product theory [10, 13], In particular, one generalizes the notions of topological freeness and invariance of a set, which are being use afterwards to obtain the Isomorphism Theorem and the complete description of ideals of C
*(X, α).
K-theory from the point of view of C*-algebras and Fredholm representations
Authors: Mishchenko Alexandr
Published: August 2006

These notes represent the subject of five lectures which were delivered as a minicourse during the VI conference in Krynica, Poland, “Geometry and Topology of Manifolds”, May, 2–8, 2004.
Tunnelling time of a gaussian wave packet through two potential barriers
Authors: Petrillo Vittoria , Olkhovsky Vladislav
Published: August 2006

The resonant and non-resonant dynamies of a Gaussian quantum wave packet travelling through a double barrier system is studied as a function of the initial characteristics of the spectrum and of the parameters of the potential. The behaviour of the tunnelling time shows that there are situations where the Hartman effect occurs, while, when the resonances are dominant, and in particular for b>π/Δk (b being the inter-barrier distance and Δk the spectrum width), the tunnelling time becomes very large and the Hartman effect does not take place.
Radiative spectra of thermal electromagnetic noise induced by planar realistic dielectrics
Authors: Dorofeyev Illarion , Fuchs Harald , Sobakinskaya Katja
Published: August 2006

Spectral characteristics of stochastic fields and their spatial derivatives in various planar structures composed by lossy materials described by realistic dielectric functions are numerically calculated based on solutions to the problems of multipolar electromagnetic fields in a plane layered geometry. A displacement of the maximum of the spectral power densities for spatial derivatives of fluctuating fields to the high-frequency domain, a resonant increase in the density of states of the fluctuating fields at the frequencies of interface excitations and interference modes for the radiative part of the spectra, the influence of geometry on the density of states, and other peculiarities are found by numerical calculations and graphically demonstrated. Interpretations of the above effects are provided.
Theoretical investigation of the electronic structure of a ferroelectric SbSI cluster at a phase transition
Authors: Audzijonis Algirdas , Gaigalas Gediminas , Žigas Leonardas , Pauliukas Audrius , Žaltauskas Raimundas , Čerškus Aurimas , Narusis Jurgis
Published: August 2006

This paper presents the theoretical investigation of energy levels of valence bands (VB) and core levels (CL) of the ferroelectric SbSl single crystals in antiferroelectric and ferroelectric phases. Since the best approximation for the deep VB levels is a calculation by the Hartree-Fock method, the molecular model of a SbSI crystal was used for calculations. This model of the crystal was also used for calculations of the total density of states. It was found that the VB and CL of this ferroelectric semiconductor are sensitive to the small lattice distortion at the phase transition, and that an average of the total density of states, when all atoms participate in oscillations of all normal modes, are more similar to the experimental X-ray photoelectron spectra (XPS). The experimental splitting of CL obtained by XPS was compared with the theoretically calculated one by two different methods. The cluster model calculations showed that the splitting of the CL in SbSI might be caused by photoelectron emission from the atoms, which have different valence state, at the surface.
Study of solid-solution hardening in binary aluminium-based alloys
Authors: Draissia Mohamed , Debili Mohamed-Yacine
Published: August 2006

Solid-solution formation in binary aluminium-based alloys is due essentially to the combined effects of the size and valence of solvent and solute atoms, as expected by the four Hume-Rothery rules. The lattice parameter of aluminium in the solid solution of the sputtered Al−Fe films is [Al-a (Å)=4.052−6.6×10−3Y]. The increasing and decreasing evolution of the lattice parameter of copper [Cu-a (Å)=3.612+1.8×10−3Z] and aluminium [Al-a (Å)=4.048−1.6×10−3X] in the sputtered Al-1.8 to 92.5 at. % Cu films is a result of the difference in size between the aluminium and copper atoms. The low solubility of copper in aluminium (<1.8 at % Cu) is due to the valences of solvent and solute atoms in contrast with other sputtered films prepared under similar conditions, such as Al−Mg (20 at. % Mg), Al−Ti (27 at. % Ti), Al−Cr (5at. % Cr) and Al−Fe (5.5 at. % Fe) where the solubility is due to the difference in size.
A theoretical approach to local attenuation measurements of shear waves by MRE. Preliminary experimental results
Authors: Klinkosz Tomasz , Lewa Czesław , Madelin Guillaume , Thiaudiere Eric
Published: August 2006

An essential highlight of the presented method is the employment of Magnetic Resonance Elastography (MRE) for local measurements of the attenuation of elastic shear waves introduced into a biological sample. Such a measurement can be accomplished by combining the MRE method with those methods, in which collective displacement of spins is induced by external physical factors, such as variable electric field, strong magnetic field gradient or longitudinal elastic wave. A theoretical basis of the method involving external factors and results of preliminary experiments have been presented in this paper.
Contribution of superstring Z′ boson on the polarization effects in proton proton collisions
Authors: Muradov Rasul , Ahmadov Azar
Published: August 2006

In this work we investigate the single- and the double-spin asymmetries at the collisions of polarized protons pp → (γ
*, Z
0, Z′) + X within the scope of QCD, the electroweak interaction and superstring E
6 theory. The helicity amplitude method is used. Analytical expressions for the single- and the double-spin asymmetries are obtained and their dependence on the transverse momentum of the lepton pair is investigated at the three different values of invariant masses of the lepton pair. The pure contribution coming from the superstring Z′ boson on the single- and double- spin asymmetries has been extracted. The results obtained allow investigation of the spin structure of the proton.
On two theorems for flat, affine group schemes over a discrete valuation ring
Authors: Vasiu Adrian
Published: August 2006

We include short and elementary proofs of two theorems that characterize reductive group schemes over a discrete valuation ring, in a slightly more general context.
On the homotopy type of (n-1)-connected (3n+1)-dimensional free chain Lie algebra
Authors: Benkhalifa Mahmoud , Abughzalah Nabilah
Published: August 2006

Let R be a subring ring of Q. We reserve the symbol p for the least prime which is not a unit in R; if R ⊒Q, then p=∞. Denote by DGL
nnp, n≥1, the category of (n-1)-connected np-dimensional differential graded free Lie algebras over R. In [1] D. Anick has shown that there is a reasonable concept of homotopy in the category DGL
nnp. In this work we intend to answer the following two questions: Given an object (L(V), ϖ) in DGL
n3n+2 and denote by S(L(V), ϖ) the class of objects homotopy equivalent to (L(V), ϖ). How we can characterize a free dgl to belong to S(L(V), ϖ)? Fix an object (L(V), ϖ) in DGL
n3n+2. How many homotopy equivalence classes of objects (L(W), δ) in DGL
n3n+2 such that H
*
(W, d′)≊H
*
(V, d) are there? Note that DGL
n3n+2 is a subcategory of DGL
nnp when p>3. Our tool to address this problem is the exact sequence of Whitehead associated with a free dgl.
Congruences, ideals and annihilators in standard QBCC-algebras
Authors: Halaš Radomír , Plojhar Luboš
Published: August 2006

We characterize congruence lattices of standard QBCC-algebras and their connection with the congruence lattices of congruence kernels.
Oscillations of linear integro-differential equations
Authors: Olach Rudolf , Šamajová Helena
Published: August 2006

Sufficient conditions which guarantee that certain linear integro-differential equation cannot have a positive solution are established.
Localization of LM
n-algebras
Authors: Chirte§ Florentina
Published: August 2006

The aim of this paper is to define the localization LM
n-algebra of an LM
n—algebra L with respect to a topology F on L; in Section 5 we prove that the maximal LM
n-algebra of fractions (defined in [3]) and the LM
n-algebra of fractions relative to an Λ—closed system (defined in Section 2) are LM
n-algebras of localization.
Left-sided quasi-invertible bimodules over Nakayama algebras
Authors: Pogorzały Zygmunt
Published: August 2006

Bimodules over triangular Nakayama algebras that give stable equivalences of Morita type are studied here. As a consequence one obtains that every stable equivalence of Morita type between triangular Nakayama algebras is a Morita equivalence.
Uncertainty relations expressed by Shannon-like entropies
Authors: Majerník V. , Majerníková Eva , Shpyrko S.
Published: August 2006

Besides the well-known Shannon entropy, there is a set of Shannon-like entropies which have applications in statistical and quantum physics. These entropies are functions of certain parameters and converge toward Shannon entropy when these parameters approach the value 1. We describe briefly the most important Shannon-like entropies and present their graphical representations. Their graphs look almost identical, though by superimposing them it appears that they are distinct and characteristic of each Shannon-like entropy. We try to formulate the alternative entropic uncertainty relations by means of the Shannon-like entropies and show that all of them equally well express the uncertainty principle of quantum physics.
Mechanism of Cu transport along clean Si surfaces
Authors: Dolbak A. , Zhachuk R. , Olshanetsky B.
Published: August 2006

Cu diffusion along clean Si(111), (110) and (100) surfaces are investigated by Auger electron spectroscopy and low energy electron diffraction. The effective diffusion coefficients of copper are measured in the temperature range from 500 to 650°C. It is shown that the Cu transport along silicon surface occurs by the diffusion of Cu atoms through Si bulk and the segregation of Cu atoms to the surface during the diffusion process. It is found that the segregation coefficients of Cu to silicon surface during the diffusion process depend on surface orientation.
On applicability of Gibbs thermodynamics to nanoparticles
Authors: Samsonov V. , Bazulev A. , Sdobnyakov N.
Published: August 2006

The problem of applicability of thermodynamics to small objects has been investigated. It is shown that the Gibbs surface phase method may be extended to nanoparticles if the effective surface tension (the specific excess free energy) is interpreted as a function of the particle radius.
Theoretical and experimental investigation of the photoacoustic effect in solids with residual stresses
Authors: Muratikov K. , Glazov A.
Published: August 2006

Modern experiment and theory in the field of residual stress detection by the photoacoustic method are summarized and analyzed. A multimode approach based on the simultaneous application of several photothermal and photoacoustic methods is proposed for the study of thermal and thermoelastic effects in solids with residual stress. Some experimental results obtained within the framework of this approach for Vickers indentation zones in ceramics are presented. The effect of annealing on the photoacoustic, piezoelectric signal for ceramics and the influence of the given external loading on the behavior of the photoacoustic signal near the radial crack tips is investigated. It is experimentally shown that both compressive and shear stresses contribute to the photoacoustic signal near the radial crack tips. The model of the photoacoustic, thermoelastic effect in solids with residual stress is proposed. It is based on the modified Murnaghan model of non-linear elastic bodies, which takes into account a possible dependence of the thermoelastic constant on stress. This model is further developed to explain the photoacoustic signal behavior near the radial crack tips. It is demonstrated that this model of the photoacoustic effect agrees qualitatively with the available experimental data.
An introduction to physical theory of molecular evolution
Authors: Luque Bartolo
Published: August 2006

This work is a tutorial in Molecular Evolution from the point of view of Physics. We discuss Eigen's model, a link between evolutionary theory and physics. We will begin by assuming the existence of (marco) molecules or replicators with the template property, that is, the capacity to self-replicate. According to this assumption, information will be randomly generated and destroyed by mutations in the code (i.e., errors in the copying process) and new bits of information will be fixed (made stable) by the existence of an external pressure on the system (i.e., selection), and the ability of the molecules to replicate themselves. Our aim is to build a model in order to describe molecular evolution from as general a standpoint as possible. As we will see, even very simple models from the theoretical point of view will have surprisingly deep consequences.
The dynamics of multiparticle collisions in motion of a granular material
Authors: Leszczyński Jacek
Published: August 2006

We consider the complex problem of how to calculate particle motions taking into account multiparticle collisions. Multiparticle contacts occur when a particle collides with neighbouring particles, so that those contacts have a direct influence on each other. We will focus on the molecular dynamics method. Particularly, we will analyse what happens in cohesive materials during multiparticle contacts. We investigated the expression of repulsive force formulated under fractional calculus which is able to control dynamically the transfer and dissipation of energy in granular media. Such approach allows to perform simulations of arbitrary multiparticle collisions and also granular cohesion dynamics.
Surface morphology of PrBa2Cu3O7-δ single crystals after the long-lasting high-temperature reduction
Authors: Łuszczek Maciej , Sadowski Wojciech
Published: August 2006

The results of the detailed scanning electron microscopy study of PrBa2Cu3O7-δ single crystals after the long-lasting high-temperature post-growth treatment are reported. The presence of the unstable decomposition products on the crystal surface indicates that the onset of superconductivity must be related to the structural transformations in the bulk (approximately 20% of the total volume of the examined crystals). The time-dependent character of the superconductivity in the Pr-123 crystals could be attributed to the migration of defects in the Pr−Ba sublattice from the bulk toward the surface.
Centrifugal (centripetal) and Coriolis' velocities and accelerations in $$ (\bar L_n ,g) $$ -spaces
Authors: Manoff Sawa
Published: August 2006

The notions of centrifugal (centripetal) and Coriolis' velocities and accelerations are introduced and considered in spaces with affine connections and metrics [ $$ (\bar L_n ,g) $$ -spaces] as velocities and accelerations of flows of mass elements (particles) moving in space-time. It is shown that these types of velocities and accelerations are generated by the relative motions between the mass elements. They are closely related to the kinematic characteristics of the relative velocity and relative acceleration. The centrifugal (centripetal) velocity is found to be in connection with the Hubble law. The centrifugal (centripetal) acceleration could be interpreted as gravitational acceleration as has been done in the Einstein theory of gravitation. This fact could be used as a basis for workingout new gravitational theories in spaces with affine connections and metrics.
On entanglement distillation and quantum error correction for unknown states and channels
Authors: Horodecki Pawel
Published: August 2006

We consider the problem of invariance of distillable entanglement D and quantum capacities Q under erasure of information about single copy of quantum state or channel respectively. We argue that any 2 ⊗N two-way distillable state is still two-way distillable after erasure of single copy information. For some known distillation protocols the obtained two-way distillation rate is the same as if Alice and Bob knew the state from the very beginning. The isomorphism between quantum states and quantum channels is also investigated. In particular it is pointed out that any transmission rate down the channel is equal to distillation rate with formal LOCC-like superoperator that uses in general nonphysical Alice actions. This allows to we prove that if given channel Λ has nonzero capacity (Q → or Q ⟺) then the corresponding quantum state ϱ(Λ) has nonzero distillable entanglement (D → or D ⟺). Follwoing the latter arguments are provided that any channel mapping single qubit into N level system allows for reliable two-way transmission after erasure of information about single copy. Some open problems are discussed.
High power self-controled volume discharge based molecular lasers
Authors: Apollonov V.
Published: August 2006

An investigation was made of the characteristics of the formation of a selfcontroled volume discharge for the pumping of CO2 lasers, i.e. self-sustained volume discharge (SSVD), which involved a preliminary filling of a discharge gap by an electron flux from an auxiliary-discharge plasma. We have found that this method was suitable for large interelectrode gaps, that distortion of the electric field in the gap by the space charge of the electron flux played an important role in the formation of the discharge and that the electrodes could be profiled dynamically during propagation of an electron flux through the discharge gap and a SSVD could form in systems with a strongly inhomogeneous field. High power SSVD based CO2 laser systems have been created and investigated.

Another type of self-controled volume discharge without pre-ionization, i.e. a selfinitiated volume discharge (SIVD), in nonchain HF lasers with SF6−C2H6 mixtures was investigated as well in our review. We have established that, after the primary local electrical breakdown of the discharge gap, the SIVD spreads along the gap in directions perpendicular to that of the electric field by means of the successive formation of overlapping diffuse channels under a discharge voltage close to its quasi-steady state value. It is shown that, as new channels appear, the current flowing through the channels formed earlier decreases. The volume occupied by the SIVD increases with increase in the energy deposited in the plasma and, when the discharge volume is confined by a dielectric surface, the discharge voltage increases simultaneously with increase in the current. The possible mechanisms which explain the observed phenomena, namely the dissociation of SF6 molecules and electron attachment SF6 molecules, are examined. A simple analytical model, which makes it possible to describe these mechanisms at a qualitative level, was developed. High power SIVD based HF(DF) lasers have been developed and tested.
Dual pairs and Kostant-Sekiguchi correspondence. II. Classification of nilpotent elements
Authors: Daszkiewicz Andrzej , Kraśkiewicz Witold , Przebinda Tomasz
Published: August 2006

We classify the homogeneous nilpotent orbits in certain Lie color algebras and specialize the results to the setting of a real reductive dual pair.

For any member of a dual pair, we prove the bijectivity of the two Kostant-Sekiguchi maps by straightforward argument. For a dual pair we determine the correspondence of the real orbits, the correspondence of the complex orbits and explain how these two relations behave under the Kostant-Sekiguchi maps. In particular we prove that for a dual pair in the stable range there is a Kostant-Sekiguchi map such that the conjecture formulated in [6] holds. We also show that the conjecture cannot be true in general.
On some properties of the functions from Sobolev-Morrey type spaces
Authors: Najafov Alik
Published: August 2006

In this paper the spaces of type Sobolev-Morrey-W
p,a,г,τl(Q,G)-are constructed, the differential properties are studied and it is proved that the functions from these spaces satisfy Holder's condition, in the case, if the domain G∋R
n satisfies the flexible λ-horn condition.
Radial-type complete solutions for a class of partial differential equations
Authors: Çetinkaya Ayşegül , Özalp Nuri
Published: August 2006

We give some fundamental solutions of a class of iterated elliptic equations including Laplace equation and its iterates.
On the first homology of automorphism groups of manifolds with geometric structures
Authors: Abe Kōjun , Fukui Kazuhiko
Published: August 2006

Hermann and Thurston proved that the group of diffeomorphisms with compact support of a smooth manifold M which are isotopic to the identity is a perfect group. We consider the case where M has a geometric structure. In this paper we shall survey on the recent results of the first homology of the diffeomorphism groups which preserve a smooth G-action or a foliated structure on M. We also work in Lipschitz category.