bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear Resonance in Neuron Dynamics
Authors: Rader Scott , Wheeler Diek W. , Schieve W.C. , Das Pranab 
Published: February 2015

Abstract
Hübler's technique using aperiodic forces to drive nonlinear oscillators to resonance is analyzed. The oscillators being examined are effective neurons that model Hopfield neural networks. The method is shown to be valid under several different circumstances. It is verified through analysis of the power spectrum, force, resonance, and energy transfer of the system.
On the Time-Independent Perturbation Theory
Authors: Campos D. 
Published: February 2015

Abstract
The time-independent perturbation theory is developed for an arbitrary operator

which can be expanded in powers of the perturbation parameter λ. A unified formulation allows the establishment of a formal interrelation between the methods of Rayleigh-Schrödinger and of Bril­ louin-Wigner. We introduce a nonunitary transformation operator to connect the nth eigenket of Ĥ(0) with the nth eigenket of Ĥ(λ) and it is proven that this operator satisfies a Lippmann-Schwinger type equation. A perturbation method based on this equation is proposed, and it is applied to describe an electron moving in a Yukawa potential.
Chemical and Topological Short Range Order of Amorphous Ti-Si Alloys
Authors: Pojtinger A. , Bellissent R. , Lamparter P. , Steeb S. 
Published: February 2015

Abstract
Amorphous Ti100 - xSix alloys (13<x<60) were produced by sputtering. Their partial structure factors were determined by X-ray and neutron diffraction. The Bhatia-Thornton density-concentration correlation function GNC(R) was calculated by a cluster relaxation model. Three-dimensional atomic clusters were produced by the Reverse Monte Carlo method. These clusters were analyzed in terms of trigonal prismatic arrangements as a structural unit. In amorphous Ti75Si25 and Ti87Si13 those Si-atoms which are surrounded by 9 Ti-atoms in the first coordination shell prefer trigonal prismatic arrangements. In the atomic clusters of amorphous Ti59Si41, Ti49Si51, and Ti40Si60, however, no preference of trigonal prisms was found.
Die Lösung der Schrödinger-Gleichung als eindimensionales Problem. II. Test an Einelektronatomen
Authors: Preuß H. , Pernpointner M. 
Published: February 2015

Abstract
As announced in part I of this work, concrete calculations on the one-electron atoms H, He+, and Li2+ are presented here. The results allow a comparison between the implemented method of discretization and other methods with respect to the one-dimensional formalism. The use of a Gaussian integral kernel makes it possible to perform the spatial integration analytically. Further­ more it is shown how fast oscillations in the curve parametrization can be avoided by the use of non-integral parameters.
Landau Theory of a System with Two Bilinearly Coupled Order Parameter sin External Field: Exact Mean Field Solution, Critical Properties and Isothermal Susceptibility
Authors: Kornyshev A.A. , Kossakowski D.A. , Leikin S. 
Published: February 2015

Abstract
We present simple description of a system with two bilinearly coupled order parameters in external field based on an exact mean-field solution of the Landau Hamiltonian. It reproduces the qualitative form of the "field-temperature" phase diagram given by a molecular-field model and by more sophisticated theories and experiments on metamagnets. The solution gives the same critical exponents as the molecular-field theory, but it is not restricted to the magnetic systems only and it is easier to handle, since it formulates the results in explicit analytical form. The susceptibility in this model does not diverge at the second order transition line (far from a higher order critical point separating the second and first order transition lines), but jumps down from the lower temperature wing to the higher temperature one. The jump amplitude is proportional to the square of the field in small fields and diverges in large fields close to the higher order critical point.
A Simplified Thermodynamic Theory for Biaxial Nematics
Authors: Papenfuß Christina , Verhás Jozsef , Muschik Wolfgang 
Published: February 2015

Abstract
A continuum theory of a biaxial nematic phase in liquid crystals is presented. The liquid crystalline ordering is described by a field of three unit vectors. Because these are macroscopic directors, the present approach is a generalization of the Ericksen-Leslie theory to biaxial nematics. The applied tools from nonequilibrium thermodynamics are classical Linear Irreversible Thermodynamics and Gyarmati's variational principle.
Comments on the Dynamical Theory of X-Ray Diffraction in Crystals
Authors: Wagenfeld H. K. 
Published: February 2015

Abstract
Von Laue reformulated Ewald's dynamical theory of X-ray diffraction in crystals by solving Maxwell's equations for an electric susceptibility which has the periodicity of the crystals lattice. Absorption was in the original paper not included. Kohler showed that in this case the electric susceptibility is directly proportional to the electron charge density within the crystal.
Von Laue assumed that the divergence of the electric field vector E is equal to the electron charge density which is excited by the electromagnetic field, and this is in accordance with Lorentz' classical electron theory. Under this assumption E is in contrast to D not a transverse wave. This is the reason that von Laue derived the fundamental equations in terms of D, and in order to obtain a simple wave equation he used the approximation 4πP = ϰD. Here P is the vector of the electric polarization and ϰ is 4π times the electric susceptibility. This approximation is well justified, and von Laue's formulation is used in most publication on this subject.
However some authors derived the fundamental equations in terms of fusing the correct relation 4πP = ϰE . In most publications they assumed that the longitudinal component of the vector E is small and neglected it. This point and the comparison with von Laue's formulation was discussed by Miyake and Ohtsuki. We show here that the divergence of E can be put zero if inelastic processes are excluded. This follows from Kohler's and Moliere's papers on the wave mechanical foundation of the dynamical theory of X-ray diffraction. However if higher perturbation terms are taken into account then the divergence of E differs from zero.
In multiple beam cases the fundamental equations are much simpler if they are expressed in terms of E. In the region of anomalous dispersion, and here in particular in the region where the X-ray energy is close and above and crystal absorption edge, the wave equations should be expressed in terms of the electric field vector E.
Calculation of Theoretical Alpha Coefficients for XRF Analysis of Major and Minor Elements in Iron-rich Geological Samples
Authors: Hua Younan , Yap C. T. 
Published: February 2015

Abstract
This paper introduces a method of calculating theorectical alpha coefficients for the X-ray fluorescence analysis of major and minor components in iron-rich samples. We choose a group of hypothetical standard samples whose average concentrations are those of the actual samples. The theoretical X-ray fluorescence relative intensities of the given components are calculated using the fundamental parameter NRLXRF program. We derived formulas from the Lachance-Traill equation and used these to calculate the basic, hybrid and modified alpha coefficients which are used respectively for the analysis of elements in compact specimens, oxides in compact specimens and oxides in diluted specimens. In order to use the theoretical alpha coefficients on-line, we also discuss the calculation of the alpha coefficients used in the D.J model.
Rotational Resolution in the VUV-Spectrum of CF3I via Infrared-Ultraviolet Double Resonance Experiments
Authors: Bahnmaier Albert H. , Jones Harold 
Published: February 2015

Abstract
This paper reports the double resonance signal observed by combination of a cw CO2 laser with a pulsed uv ionisation technique (REMPI). The infrared laser was used to pump a single ro-vibrational transition of the ν1 band of CF3I, and the resulting change in the two-photon, vuv spectrum was observed. Signals were detected under conditions of mass selectivity using a time of flight mass spectrometer.
Previously unpublished data from infrared-microwave double resonance experiments are also included.
EXAFS Study on the Phase Transition (Phase α’-δ) in CH3NH3I
Authors: Ishida Hiroyuki , Maeda Hironobu , Hirano Akiko , Fujimoto Tamotsu , Kubozono Yoshihiro , Kashino Setsuo , Emura Shuichi 
Published: February 2015

Abstract
The local structure of CH3NH3I around the I- ion in Phase α' and δ was studied by iodine K-edge EXAFS. The crystal structure in Phase α' was redetermined by single crystal X-ray diffraction. The Debye-Waller factor σ(2) derived from EXAFS spectra shows an anomalous behavior around the order-disorder transition temperature from Phase δ to α'. The phase transition has been interpreted as the disordering process which involves not only the H atoms but also the C atoms in the cation.
λ-Transition to the Bose-Einstein Condensate
Authors: Grossmann Siegfried , Holthaus Martin 
Published: February 2015

Abstract
We study Bose-Einstein condensation of comparatively small numbers of atoms trapped by a three-dimensional harmonic oscillator potential. Under the assumption that grand canonical statis­tics applies, we derive analytical expressions for the condensation temperature, the ground state occupation, and the specific heat capacity. For a gas of TV atoms the condensation temperature is proportional to N1/3, apart from a downward shift of order N-1/3. A signature of the condensation is a pronounced peak of the heat capacity. For not too small N the heat capacity is nearly discon­tinuous at the onset of condensation; the magnitude of the jump is about 6.6 N k. Our continuum approximations are derived with the help of the proper density of states which allows us to calculate finite-AT-corrections, and checked against numerical computations.
On the Structure of Moltenand Amorphous Cu84.3P15.7by X-ray Diffraction
Authors: Hagenmayer R. M. , Lamparter P. , Steeb S. 
Published: February 2015

Abstract
The atomic distances in molten Cu84.3P15.7 at 770°C are smaller than those in the amorphous state at room temperature. This follows from the pair correlation functions obtained from the total structure factors. Since the weighting factors are rather inconvenient, it is not possible to draw conclusions concerning short range order in amorphous or molten Cu84.3P15.7.
Small angle scattering with the amorphous specimen shows up regions with a radius of gyration of 14 Å, whose density is different from the surrounding matrix.
Polarized Oxygen Kα and Copper Lα X-Ray Emission Spectroscopy of YBa2Cu3O7
Authors: Kottmann A. , Siebinger R. , Steeb S. 
Published: February 2015

Abstract
The high temperature superconductor YBa2Cu3O7 is characterized by a very anisotropic structure. The electronic structure of this compound is studied using high resolution valence band spectroscopy within an electron probe microanalyzer. From single crystals and melt-textured specimens,orientation dependent Cu-Lα spectra are obtained using a beryl crystal. The Cu-Lα spectra with polarization parallel to the z-direction show a larger energetic breadth compared to those obtained with polarization perpendicular to z. This is caused by occupied Cu3d3z
2-r
2 like states, as could be shown by other workers using cluster calculations.
With a chlinochlore crystal, the polarized O-Kα, spectra can be used to investigate the orientation of single crystal areas. The spectra map the bandlike O2p states. In contrast to the Cu-Lα spectra,the partial O -Kα spectra agree with band structure calculations in the local density approximation done by other workers.
High Resolution NMR Spectroscopy on Whole-Body Imagers:Optimized Single-and Multi-Pulse Experiments in Vitro
Authors: Schick Fritz 
Published: February 2015

Abstract
From 100 ml spherical glass bottles filled with aqueous solutions and suspended in a homogeneous magnetic field, NMR spectra with linewidths of about 0.7 Hz were achieved in single-pulse and multi-pulse spectra. A relatively wide receiver coil as the body coil or the standard head coil of the manufacturer were employed to acquire spectra after different non-localized pulse sequences. Examples of single-pulse spectra and double spin-echo spectra of aqueous solutions with lactate, citrate, or glucose are demonstrated and discussed. The fact that all experiments can be performed using well-defined pulse angles acting on the entire sample at the field strenght of the whole-body unit allows to determine the characteristics (e.g. chemical shift differences, coupling constants) of spin systems of biologically important molecules precisely, without need for additional spectrometers. Constant flip angles are advantageous for adequate theoretical analysis of spectra from coupled spin systems. The effects of a defined "misadjustment" of the transmitter on the spectra can be measured directly, whereas localized methods always yield a superposition of signals due to the distribution of flip angles inside the selected volume. In some cases, optimized sequence parameters for localized examinations in vivo can be derived numerically from the analyzed coupling data.
Absorption Model of Hydrogenic Atoms and Ions by Metal Surfaces
Authors: Erkovitch O.S. , Komarov V.V. , Popova A.M. , Enderle M. , Melsheimer O. , Neumann H. 
Published: February 2015

Abstract
A model of the interaction of thermal atoms and ions with metal surfaces is presented. The model is based on the multi-particle density functional method. This method is applied to describe first the properties of the electron gas on the metal surface and second to analyze the effective potential of the Hydrogenium atom in the vicinity of the metal surface.
Gibbs Transfer Energies of Some Uni-Univalent Salts in Water—N-Methyl-2-Pyrrolidinone Solvent Mixtures at 30°C
Authors: Varadarajan T. K. , Ramakrishna T. V. , Kalidas C. 
Published: February 2015

Abstract
The standard Gibbs transfer energies of some uni-univalent electrolytes like potassium picrate, tetraphenylarsonium picrate, potassium and silver tetraphenyl borate were determined in water + N-Methyl-2-Pyrrolidinone mixtures from solubility measurements at 30 °C. They were split into respective ionic values on the basis of the reference electrolyte method using tetraphenylarsonium tetraphenylborate. The variation of transfer energies of the ions with composition of solvent are examined and discussed in terms of the possible ion-solvent interactions.
Differential Thermal Analysis (DTA) and Dielectric Studies of 4 -(trans-4-Heptyl-Cyclohexyl)-benzonitrile (7PCH) under High Pressure
Authors: Brückert T. , Büsing D. , Würflinger A. 
Published: February 2015

Abstract
With the aid of DTA the phase diagram of 4-(trans-4-heptyl-cyclohexyl)-benzonitrile, 7PCH, was redetermined. Dielectric studies on the static and complex permittivity have been performed on 7PCH in the pressure range 0.1 -220 MPa, the frequency range 1 kHz-13 MHz and the temperature range 290-380 K. For the slow relaxation process in the nematic phase, characterized by the relaxa­tion time tII , we have calculated the activation volume, Δ ≠
V
II, of about 80 to 60 cm3/mol (decreasing with increasing temperature), and the activation enthalpy, Δ ≠
H
II, of approximately 70 kJ/mol. The isochoric activation energy, Δ ≠
U
II, amounts to about 36 kJ/mol. The pressure dependence of Δ ≠
H
II is less pronounced compared with previous findings for 5PCH and 7CB. Estimates of t0 (extrapo­lated from the relaxation time in the isotropic phase) allow the calculation of the retardation factor g
II = tII/t0 that is analysed in terms of theories of Martin-Meier-Saupe and Coffey in order to evalu­ate the nematic potential q. Using data for the order parameter 5 from NMR studies it was possible to determine the strength of the interaction potential in the nematic phase and to check the relation q~S which is valid at p = const., but not at V = const. The results are compared with recent findings for other homologous series.
Study of the Dielectric Properties of 7PCH (4 -(trans -4 -Heptyl-Cyclohexyl)-benzonitrile)
Authors: Urban S. , Gestblom B. , Brückert T. , Würflinger A. 
Published: February 2015

Abstract
The results of dielectric studies of 7PCH (4-(trans-4-heptyl-cyclohexyl)-benzonitrile) in the nematic and isotropic phases are presented. The complex dielectric permittivity, ε*=ε' - i ε", was measured in the frequency range 1 kHz-5 GHz, with the use of an impedance analyzer and a time domain spectroscopy (TDS) set-up. The relaxation times: longitudinal tII, and transverse t^ in the nematic phase, and tis in the isotropic phase, were obtained. They served for calculation of the activation barriers for different molecular rotation processes occurring in both phases. Additionally, the retardation factors g
II and g
^ were calculated. Two theoretical models (Meier-Saupe and Coffey et al.) were applied for tne calculation of the nematic potential q. A critical analysis of accessible literature data on the order parameter S is given. On that basis the relation q - SS is tested. The obtained values of the strength parameter S are lower for 7PCH than for 5PCH. Possible contribu­tions to the total energy barrier hindering the molecular rotation around the short axis in the nematic phase are considered.
Density and Electrical Conductivity of NaCl - CoCl2 and NaCl - NiCl2 Molten Mixtures
Authors: Red'kin A.A. , Salyulev A.B. , Smirnov M.V. , Khokhlov V.A. 
Published: February 2015

Abstract
The density and electrical conductivity of cobalt and nickel dichlorides and their solutions in molten sodium chloride have been measured. The density was measured by a dilatometric method, and the electrical conductivity by an AC technique. The molar volume and equivalent conductance were calculated.
Surface Growth and Oxidation of Soot Particles under Flame Conditions
Authors: Schäfer Th. , Mauß F. , Bockhorn H. , Fetting F. 
Published: February 2015

Abstract
Surface growth and oxidation of soot particles is investigated in premixed counter flow flames. Surface growth rates and soot oxidation rates can be evaluated from the measured appearance rates of soot and the calculated surface growth rates derived from the HACA-mechanism. The dependence of surface growth rates and soot oxidation rates on composition of the gas phase, temperature and “surface concentration” is discussed. A mechanism of soot oxidation accounting for the experimental findings is suggested.
Defect Chemistry of “BaCuO2” II. Transport Properties and Nature of Defects
Authors: Chiodelli G. , Anselmi-Tamburini U. , Arimondi M. , Spinolo G. , Flor G. 
Published: February 2015

Abstract
The charge transport properties of "BaCuO2" with 88:90 (Ba :Cu) cation ratio were characterized by thermopower, electrical conductivity and ionic transport number measurements in a wide range of temperature and oxygen partial pressure conditions.
The nature of carriers is always represented by small polarons due to self-trapping of the electronic holes generated by the oxygen non-stoichiometry equilibrium.
Some anomalies in carrier mobility as a function of temperature are shown not to be related to incomplete ionization of oxygen atoms on interstitial sites
On the Paddle -Wheel Mechanism for Cation Conduction in Lithium Sulphate
Authors: Lundén Arnold 
Published: February 2015

Abstract
A few high-temperature sulphate phases are both plastic crystals and solid electrolytes, the latter because the hindered rotational motion of the sulphate ions enhances the mobility of the cations. This interpretation has been called the paddle-wheel model, and it is obvious that cation migration becomes a much more complicated process in a plastic ionic crystal than in a crystal with a stiff, time-independent structure. Thus, there are strongly enhanced contributions from conventional migration mechanisms, such as jumping from well-defined lattice sites, but it is evident that there also are contributions which are specific for the paddle-wheel mechanism. By the molecular dynamics study by Ferrario, Klein and McDonald it has become possible to identify separately the contributions from centre-of-mass displacements and rotations of the sulphate group. Information in this direction has also been obtained recently by Karlsson and McGreevy in a neutron powder diffraction study where the reverse Monte Carlo method is used for modelling the data. The latter authors have modified the terminology slightly, which causes confusion regarding the meaning of the term "paddle-wheel mechanism". The "paddle-wheel" enhances not only bulk migration but also migration along interfaces and surfaces. The mobility can also be increased for monovalent anions present. Some examples are given of other types of mobility enhancements which also are due to libration or rotation of polyatomic anions.
Nuclear Physics with Antiprotons
Authors: Egidy T. von , Hartmann F.J. , Schmid S. , Schmid W. , Gulda K. , Jastrzebski J. , Kurcewicz W. , Lubinski P. , Pienkowski L. , Trzcinska A. , Hilscher D. , Bohne W. , Goldenbaum F. , Jahnke U. , Polster D. , Rossner H. , Iljinov A. S. , Mebel M.V. , Nedorezov V.G. , Sudov A. S. , Eades J. , Neumaier S. 
Published: February 2015

Abstract
Information on the neutron distribution in the nuclear periphery was obtained by the annihilation of stopped antiprotons and the yield of residual nuclei. The last atomic transitions of the antiproton before annihilation gives complementary results. Properties of very hot nuclei (up to 1 GeV) after annihilation of stopped antiprotons were studied by neutron emission and fission. Absolute prob­ abilities of fission induced by stopped and fast antiprotons were determined. The experimental data are compared with elaborate calculations taking into account the annihilation process, the fast cascade and pre-equilibrium emission, thermalisation, particle evaporation and fission.
Notiz: Dynamic Dielectric Properties of Some Alkylamino Ethoxylates
Authors: Saad A. , Becker U. , Stockhausen M. , Barakat Y. 
Published: February 2015

Abstract
Nine ethoxylated (EO) alkyl amines, (CnH2n + 1) N(EO)x; H(EO)y H, with n = 10 to 16 and p = x + y = 7.6 to 14.5, were studied as pure liquids with respect to their dielectric relax­ ation behaviour over the frequency range 5 MHz to 36 GHz at 20 °C. The broad and structureless dielectric loss spectrum is similar for all samples. It can be described by a main lower frequency spectral component of Havriliak-Negami type plus two minor, higher frequency Debye type components. The relaxation parameters are reported. Dynamic Dielectric Properties of Some Alkylamino Ethoxylates
Sliding Dynamics of the Frenkel-Kontorova Model
Authors: Strunz T. 
Published: February 2015

We investigate the dynamics of the Frenkel-Kontorova model with inertia and damping under a uniform driving force.
We consider the dependence of the velocity-force characteristic, and the corresponding sliding states on the damping: In the overdamped limit the asymptotic solution with nonzero sliding velocity is unique and periodic. Periodic solutions and their stability can also be calculated for decreasing damping, where the dynamics is dominated by resonance effects of the underlying potential with the phonon modes of the chain. The asymptotic velocity is not unique, leading to hysteresis in the velocity-force characteristic. In addition to periodic sliding states, which lose stability for decreasing damping, quasiperiodic or spatio-temporal chaotic behavior occurs.
Nonlinear Dynamics in the Ultradian Rhythm of Desmodium motorium
Authors: Chen Jyh-Phen , Engelmann Wolfgang , Baier Gerold 
Published: February 2015

Abstract
The dynamics of the lateral leaflet movement of Desmodium motorium is studied. Simple periodic, quasiperiodic and aperiodic time series are observed. The long-scale dynamics may either be uniform or composed of several prototypic oscillations (one of them reminiscent of homoclinic chaos). Diffusively coupled nonlinear oscillators may account for the variety of ultradian rhythms.