bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zur spektralen Verteilung von Temperatur‐ und Konzentrationsschwankungen in turbulenten Strömungen
Authors: Szablewski W. 
Published: May 2007

AbstractEs wird die dem −5/3‐Potenzgesetz des Spektrums der turbulenten Temperatur‐(Konzentrations‐)schwankungen äquivalente Form des Transfers eines passiven Skalars hergeleitet, die einen Ansatz von CORRSIN bestätigt. Auf dieser Grundlage ergibt sich für den Übergang vom Trägheits‐ und Konvektionsbereich in den Zähigkeits‐ und Diffusionsbereich das Spektrum der Temperaturschwankungen in Abhängigkeit von der Prandtlzahl (Analogon zu KOVASZNAYSFormel für das Spektrum der Turbulenzenergie). Qualitative Übereinstimmung besteht mit Messungen des eindimensionalen Spektrums im Trägheits‐Diffusionsunterbereich und im Zähigkeits‐Konvektionsunterbereich.
Amplitudenverhältnisse bei der Reflexion und Brechung des Lichtes an der Grenzebene zwischen isotropen und anisotropen Medien
Authors: Wünsche A. 
Published: May 2007

AbstractEs werden die Amplitudenbeziehungen für die elektrischen Felder ebener monochromatischer Wellen bei der Reflexion und Brechung an der Grenzebene zwischen isotropen und beliebig anisotropen Medien bei Einfall sowohl vom isotropen als auch vom anisotropen Medium her aus der Maxwellschen Theorie abgeleitet. Weiterhin werden die vektoriellen Amplituden der uniradialen Schwingungen bestimmt. Folgende Spezialfälle der allgemeinen Formeln werden betrachtet: 1. senkrechter Einfall, 2. optische Achse in Richtung der im anisotropen Medium reflektierten bzw. gebrochenen Welle, 3. senkrechte und parallele Polarisation der Teilwellen im anisotropen Medium bezüglich der Einfallsebene.
Untersuchung der Protonen‐Spin‐Gitter‐Relaxation in der smektisch‐C‐ und der nematischen Phase langkettiger Homologer von PAA
Authors: Heinze Ekkehard , Grande Siegbert , Lösche Arthur 
Published: May 2007

AbstractEs werden Ergebnisse einer vergleichenden Messung der Temperatur‐, Frequenz‐ und Winkelabhängigkeit der Spin‐Gitter‐Relaxationszeiten im Zeeman‐ und Dipolsystem, T1 und T1D, an langkettigen Homologen des meistuntersuchten Flüssigkristalls PAA vorgestellt. Diskutiert wird insbesondere die Temperaturabhängigkeit dieser Zeitkonstanten in der nematischen im Vergleich zur smektischen Phase.
Phonon Scattering at Multi‐Level Impurities
Authors: Michel H. , Wagner M. 
Published: May 2007

AbstractA Green's function technique is used to calculate the dispersion and damping of phonons at tunneling centers with internal degrees of freedom. Starting from a model for tunneling centers oriented in 〈100〉‐orientations, we decouple the evolution hierarchy of Green's functions in second order. A further iteration of the resulting integral equation leads to dispersion and damping. The frequency power law differs for the even and odd parity phonons, which are involved in the local transitions. In a second approach the damping is recalculated by means of a scattering formalism, which steps directly into the fourth order. This direct method shows an extension of the renormalization of the local energy spacings and of the homogeneous linewidths.
Gravitational Field Equations of Fourth Order and Supersymmetry
Authors: v. Borzeszkowski H. V. , Treder H.‐J. , Yourgrau W. 
Published: May 2007

AbstractWe discuss the field equations which stem from a variational principle containing the quadratic terms αRμνRμν and βR2 besides the Einstein‐Hilbert Lagrangian R. Comparison of this theory with a pure theory of fourth order shows that R must necessarily be included if we wish to interpret the field equations as gravitational equations. The Einstein‐Bach‐Weyl theory (α = −3β) has the property of being a theory of “supergravitation”. Apart from gravitons without rest‐mass, we have here only one additional kind of particles with rest‐mass. Their mass may be determined by Planck' slength (hG/c3)1/2. The occurrence of those particles results from the breakdown of a “supersymmetry”, that is of the conform invariance. The Einstein tensor Eμν  Rμν −1/2gμνR can be regarded as a source of the gravitons without rest‐mass.
Classical Spontaneous Breakdown of Symmetry and Induction of Inertia
Authors: Liebscher D.‐E. , Yourgrau W. 
Published: May 2007

AbstractWe consider the existing forms of inertia‐free mechanics as attempts to reduce the a priori properties of space‐time and to search for the mechanism inducing the actual properties of local space‐time regions by the matter‐distribution in the universe. We explicate the problem of the induction of the local Lorentz structure of space‐time and establish a first solution.
EINSTEINS Feldtheorie mit Fernparallelismus und DIRACS Elektrodynamik. II. [Identitäten und Erhaltungssätze]
Authors: Kreisel Eckhard 
Published: May 2007

AbstractDie Identitäten und Erhaltungssätze der in [1] mit der Diracschen Elektrodynamik in Verbindung gebrachten Tetradentheorie der Gravitation werden untersucht. Die Energie‐Impuls‐Erhaltung ist der Erhaltung der vier „Maxwellströme”︁ äquivalent. Die Tetradenfeldgleichungen implizieren die Gleichheit von Einsteintensor und symmetrisiertem kanonischen Energie‐Impulstensor.
Neutron‐Proton Ratio at Different Atmospheric Depths and Sea Level Neutron Spectrum Derived from the Primary Nucleon Spectrum
Authors: Bhattacharyya D. P. , Ghosh A. K. , Basu D. 
Published: May 2007

AbstractThe differential neutron spectrum at sea level has been calculated using the conventional phenomenological model after ASHTON. The energy dependence of nucleon‐air nucleus inelastic interaction cross section is assumed in these calculations. The derived sea level neutron spectrum from the satellite measured primary nucleon spectrum of GRIGOROV et al. fits well the experimental neutron spectrum of ASHTON and COATS. The neutron‐proton ratios calculated for different atmospheric depths is in accord with the measured data (AGUIRRE).
Thermodynamic Properties of Highly Degenerate Multicomponent Plasmas
Authors: Stolzmann W. , Kraeft W.‐D. 
Published: May 2007

AbstractOn the basis of numerical evaluations the themodynamic functions of multicomponent plasmas such as free energy, pressure and chemical potential are discussed in regions where bound states may be excluded, but at any degree of degeneration. As an example, the electron hole drop transition in an excitonic plasma in Germanium is considered.
A Partial Wave Analysis of the Reaction π+p→ (π+π−π0) Δ++ at 16 GeV/c
Authors: Otter G. , Rudolf G. , Naumann Th. , Nowak S. 
Published: May 2007

AbstractA partial wave analysis of the 3π‐system has been performed for the reaction π+p→ (π+π−π0) Δ++ (1232) at 16 GeV/c. Beside the well‐established A20 (1300), the resonant state ω* with isospin I = 0 and spin‐parity JP = 3− decaying mainly into (ϱπ) has been found. Its mass and width have been determined to be M = (1.71 ± 0.03) GeV and Γ = (0.22 ± 0.10) GeV. The cross section for the reaction π+p→ ω* (1700) Δ++ (1232) is σ = (12 ± 6) μb.
The Time‐space‐dependent Power Spectrum for the Description of Nonstationary and Inhomogeneous Electromagnetic Fields
Authors: Ponath H.‐E. , Schubert M. 
Published: May 2007

AbstractThe nonstationary analogue to the stationary Wiener Khintchine theorem is considered and applied to the multi‐dimensional case of temporally nonstationary and spatially inhomogeneous electromagnetic fields. The time‐space‐dependent power spectrum of these fields is introduced, and its connection with important measurable quantities is discussed. The dispersions relations (the mutual dependence of the Fourier variables ω, k belonging to the time and space coordinates t, 𝔯) are included into the consideration. The variable Fourier amplitudes are compared with the conventionally used slowly varying field amplitudes. The transition to the stationary limiting case is carried out.
Three‐Body Problems with Separable Two‐Body Interactions
Authors: Osman A. 
Published: May 2007

AbstractFaddeev equations for the three‐body problem are reconsidered using separable two‐body interactions. The separable potentials reduce the Faddeev equations to coupled integral equations in one continuous variable. Numerical calculations for the resulting integral equations are carried out using separable two‐body interactions which include both attraction and repulsion potentials. Each of the separable attraction and repulsion potentials used is taken as a spin‐dependent central force together with tensor forces. The potential functions of the different parts of the two‐body interactions are taken to be of the Yamaguchi, Gaussian, Tabakin, Mongan and Reid forms. Each of the nuclei 6Li, 9Be and 12C is taken to be composed of three particles according to the cluster structure description of nuclei. The binding energies of the nuclei 6Li, 9Be and 12C are calculated as a three‐body problem and in the framework of the Faddeev formalism.
Einheitliche Feldtheorie mit Fernparallelismus und Diracs Elektrodynamik. V (Die asymptotische Form der statischen Felder in der Einheitlichen Feldtheorie mit Fernparallelismus)
Authors: Treder Hans‐Jürgen 
Published: May 2007

AbstractDiskussion des asymptotischen Verhaltens von statischen Bezugstretaden‐Feldern, die Lösungen der verallgemeinerten Einstein‐Maxwellschen Feldgleichungen in der einheitlichen Feldtheorie mit Einsteinschem Fernparallelismus sind. Solche Lösungen entsprechen stabilen Wolken von Elektronen aus Diracs klassischer Elektrodynamik.
Phase Transitions in Nonideal Alkali‐ and Noble Gas Plasmas
Authors: Dienemann H. , Clemens G. , Kraeft W.‐D. 
Published: May 2007

AbstractIn this paper the plasma composition of Cs‐ and Xe‐plasmas was determined for temperatures between 3000 K (Cs) or 8000 K (Xe) and 25000 K and for free charge carrier densities between 1023 m−3 and 5. 1028 m−3. Besides the Coulomb forces we took into account also short range forces between the charged particles and between the atoms. Effects of degeneration were neglected.The thermodynamic stability is discussed, and the influence of the different interaction contributions between the particles on the border of the instability region is considered. Especially the Mott transition is dealt with.
Inelastic Interactions of 50 GeV/c Negative Pions with Nucleons
Authors: Badawy O. E. , Hussein M. T. 
Published: May 2007

AbstractThe multiparticle production in π− ‐ N interactions at 50 GeV/c incident pion momentum is studied in the frame of the formation of resonance and the fireball production. The cross‐sections of production of the Δ(1236), N (1688), N (2220) and ϱ° resonances are measured.The fireballs are studied by the use of the Doller‐Walker plot and the target plot methods. The mass, emission angle and the velocity of each fireball are determined.
Anticorrelations in Nondegenerate Parametric Three‐Wave Interaction
Authors: Paul H. , Brunner W. 
Published: May 2007

AbstractIt is shown that the anticorrelations in the photon numbers of the signal and the idler wave, respectively, generated in parametric three‐wave interaction under suitable conditions, violate an inequality well‐known in classical communication theory. Hence, it must be concluded that these anticorrelations reflect a typical quantum mechanical feature of light. In fact, this nonclassical behaviour is responsible for the occurrence of photon antibunching in the superposition field made up of both the signal and the idler wave, as will be pointed out in some detail.
Multichannel and Multidimensional Bargmann Potentials
Authors: Plekhanvov E. B. , Suzko A. S. , Zakhariev B. N. 
Published: May 2007

AbstractThe class of potential matrices for which coupled channel Schrödinger equations have exact solutions is presented. This is achieved due to degeneration of the kernel of the inverse‐problem integral equation with respect to the channel indices, in addition to separability of its coordinate dependence. No attention has been paid before to this fact. Maybe therefore there was no satisfactory multichannel generalization of Bargmann potentials.Partially nonlocal Bargmann potentials for multidimensional and many‐particle systems are constructed. Examples of new transparent potentials are given.
On Coherent States of Relativistic Particles
Authors: Ternov I. M. , Bagrov V. G. 
Published: May 2007

AbstractSome general properties of coherent states of a particle in quantum mechanics are discussed and examples of relativistics coherent states of an electron moving in a steady and homogeneous field and in a non‐stationary external field of special kind are presented. In particular cases this field may be a plane wave, a Redmond field (a superposition of plane wave and homogenous magnetic field), a superposition of a Redmond field and a longitudinal electric field or other physically interesting fields.
Autocatalytic Models for Turbulent Flows in Tubes
Authors: Ebeling W. 
Published: May 2007

AbstractIt is shown that the experimentally observed velocity profiles and drag coefficients may be explained on the basis of autocatalytic models which lead to reaction‐diffusion equations for the exchange quantity. The first (zero) solution of these equations corresponds to the laminar flow and the second one (different from zero) corresponds to the turbulent flow.
Kinetics of the Ar‐Hg Plasma of Fluorescent Lamp Discharges. II. Ar Partial Pressure and Discharge Current Variation
Authors: Winkler R. B. , Wilhelm J. , Winkler R. 
Published: May 2007

AbstractIn continuation of recent kinetic investigations of the main macroscopic quantities of the Ar‐Hg plasma which include realistic electron kinetics at various Hg partial pressures, this paper deals with the study of the macroscopic plasma behaviour at varying discharge current and buffer gas pressure respectively in a wide range of practical interest. By simultaneously solving the particle balances for the various kinds of excited Hg atoms, the current balance as well as the electron Boltzmann equation for such a mixture plasma, the densities of the electrons and excited Hg atoms, the electron energy distribution function, the energy budget of the electrons and the ultraviolet resonance radiation outputs could be determined, analysed and in part compared with experimental data available in the literature. In particular, a good agreement between theoretical and experimental results for the densities of the excited Hg atoms as well as for both resonance radiation outputs was found for a wide range of both considered parameters.
Stochastic Bifurcations in a Bistable Reaction‐Diffusion System with Neumann Boundary Conditions
Authors: Malchow H. , Ebeling W. , Feistel R. , Schimansky‐Geier L. 
Published: May 2007

AbstractIt is shown for a special bistable reaction‐diffusion model that an external noise shifts deterministic bifurcation maps or generates new bifurcations. Numerical results and an analytical approximation for the bifurcation map of the stationary probability density distribution of the mean concentration in a discrete model are given. The functional Fokker‐Planck equation is solved approximately.
Quantum Gravity and Quantum Nondemolition Measurements
Authors: v. Borzeszkowski H.‐H. , Treder H.‐J. 
Published: May 2007

AbstractIt is shown that in Quantum Gravity, and more general: in Grand Unified Theory incorporating General Relativity on a basic level, there arise necessarily absolute limitations on measurement which one cannot evade by any “quantum nondemolition measurements”. This fact is demonstrated not to oppose the existence of certain approximations to the full theory where these limitations do not arise.
Remark on Groups and Internal Structure in Continuum Mechanics
Authors: Günther H. 
Published: May 2007

AbstractAny mechanical motion within a solid is subjected to the group of external motion (Galilean group or if necessary for relativistic mechanics the Lorentz group) and to the internal „quasi Lorentz”︁ grouplqbeing independent of the external one. Since the effect of the external group always may be simulated by a system of external forces, any internal property is subjected tolq(e.g. quasi masses of defects). The principle of minimal coupling explicitely used in 1969 by KLUGEfor mechanical defects within a solid, being extended in 1983 by KADICand EDELENby the help of Yang‐Mills‐theory for introducing phenomenological terms of inertia for mechanical defects, is leading to the relation with the field theoretical masses for defects as in electrodynamics.
Analysis of Low‐energy α‐4He Elastic Scattering Process in Direct Channel Regge‐Pole Formalism
Authors: Majumdar D. , Chowdhury A. Roy , Roy T. 
Published: May 2007

AbstractThe elastic scattering of low‐energy α‐particles by a 4He target has been analysed within the frame‐work of a modified Regge‐Pole model which reproduces the partial wave phaseshifts in an elegant and simple way and describes all other relevant features of the scattering phenomena.
A Two Phase Description of Hot Dense Nuclear Matter and Quark Gluon Plasma
Authors: Kämpfer B. , Schulz H. , Horowitz C. J. 
Published: May 2007

AbstractA two‐phase model of nuclear matter and quark gluon plasma is presented. Nucleon‐nucleon interaction is treated by the mean field theory while the pion‐nucleon interaction is taken into account explicitly by using the spectrum of pionic excitations in nuclear matter. Interactions in the quark‐gluon plasma are included by first‐order corrections to the bag model equation of state. We find large pionic excitations near the constructed phase border line in the fragmentation region.
A Dualistic Approach to Gravitation
Authors: Mahanta M. N. 
Published: May 2007

AbstractA systematic account of a new dualistic approach to gravitation developed over the years 1979‐83 by the author is presented. The main idea of this article is to fill up the gaps in the exposition and physical interpretation rather than any important extension. We propose here a dual theory for gravitation. In the exact form it is supposed to be appropriate for microscopic (subnuclear) phenomena and in an averaged out form (may be more than once averaged) appropriate for a description of the usual gravitation of macroscopic bodies. A parallel can be found in the case of the Lorentz and Maxwell theories of electromagnetic phenomena. When sources are present the macroscopic theory is the same as the conventional Einstein theory but in the absence of sources space‐time is flat ruling out the existence of gravitational waves in this approach. Experimental verification of this should be a test case for the validity of the theory.
On Equilibrium Configurations in Continuum Mechanics of Structural Defects
Authors: Günther H. 
Published: May 2007

AbstractWe consider the determination of the theory by a second order tensor field gik and affinity Γfik. By variational principle for Einstein‐Hilbert Lagrangian solid state equilibrium positions of the ideal and real crystal will be described. On account of external Galilei‐invariance this theory affords an invariant three dimensional geometry at most being able to produce a stable static equilibrium of defects. The motion of defects is related to the theory of invariants of the internal group of field equations produced by this theory in strong analogy to Maxwell's electrodynamics. The elastic ether concept for the theory of light affords the idea of a gauge field approximation of continuum mechanics fitting linearized Einstein‐Hilbert Lagrangian approach. The stress and strain space duality has to be understood on this background.
A Relativistic Model of the Isotropic Oscillator
Authors: Atakishiyev N. M. , Mir‐Kasimov R. M. , Nagiyev Sh. M. 
Published: May 2007

AbstractFor a three‐dimensional model of the harmonic oscillator in the relativistic configurational r‐representation wave functions in the spherical coordinates r = (r, Θ, ϕ) are found. The generating function, orthogonality and various recurrence relations for the radial part of the wave function are obtained. The radial and orbital quantum numbers raising and lowering operators are defined and the dynamical symmetry group is constructed by means of the Infeld‐Hull factorization method.
Lebensdauermessung am Ionenstrahl bei kollinearer Laseranregung
Authors: Breunig Th. , Elbel M. , Quad R. 
Published: May 2007

AbstractDie Methode der kollinearen Laserspektroskopie, die sich durch eine Reduktion der Dopplerbreite um bis zu zwei Größenordnungen auszeichnet, erlaubt auch eine Bestimmung der Lebensdauer angeregter Ionenterme nach dem Verfahren des Level‐Crossing. Diese Methode ist attraktiv, weil die Ionen im Strahl in fast idealer Weise von Umgebungseinflüssen frei sind. Die Restdopplerbreiten sind allerdings noch breit gegen natürliche Linienbreite und Laserlinie. Wir konnten zeigen, daß in diesem Fall Lorentzkurven erhalten wurden, die mit Summen von Gaußkurven multipliziert sind. Die letzteren sind meist merklich breiter als die Lorentzkurven, überdies berechenbar, wenn man die Geschwindigkeitsverteilung der Ionen gemessen hat. Experimentell beobachtete Einbrüche in der Linienmitte wurden auf optisches Pumpen zurückgeführt und durch Lösen der Bewegungsgleichungen der beteiligten statistischen Tensoren verifiziert. Lebensdauern zweier Terme konnten ermittelt werden.
Das EPR‐Paradoxon als makroskopisches Experiment und seine Auswirkungen auf unsere Vorstellung von Physik
Authors: Ludwig G. 
Published: May 2007

AbstractEs soll gezeigt werden, daß die EPR‐Experimente allein im makroskopischen Bereich der Apparaturen beschrieben werden können. Diese Beschreibung oder auch die entsprechende mit Hilfe von Mikrosystemen ist ohne jede Widersprüche. Eine ontologische Interpretation der Experimente ist sowohl für die makroskopische wie mikroskopische Beschreibung der Experimente problematisch. Die korrekte, physikalische Beschreibung der EPR‐Experimente führt dazu, viele Vorurteile darüber zu vermeiden, was Physik ist.
Physikalische Bilder ‐ Besinnung auf eine fachdidaktische Aufgabe
Authors: Mann Are 
Published: May 2007

AbstractPhysiker arbeiten an Darstellungen der Natur, d.h. sie suchen mit physikalischen Mitteln Bilder zu schaffen, die ihnen Naturzusammenhänge klarer und eindringlicher vor Augen führen. Schulunterricht soll jedem die Möglichkeit eröffnen, Physik in solchem Sinne ‐ wenn auch in bescheidenem Rahmen ‐ selbst zu treiben. Allzuoft bleibt diese Wissenschaft jedoch den Schülern ein kahles Gerüst und führt sie nicht zu inhaltsreichen Bildern. Es wird vorgeschlagen, Schulphysik mehr unter dem Gesichtspunkt einer Kunst zu sehen, die wirklich zu betreiben aber Muße erfordert.
Photo‐Induced Metastable Effects in Hydrogenated Amorphous Silicon (a‐Si:H)
Authors: Fuhs W. , Mell H. , Stuke J. , Thomas P. , Weiser G. 
Published: May 2007

AbstractLight induced changes of electronic properties are studied in glow discharge deposited a‐Si: H‐films by ESR, field effect, DLTS and electronic transport. These effects are caused by silicon dangling bonds generated by recombination processes, which raise the density of states near midgap. The concomitant increase of potential fluctuations indicates that these defects are inhomogeneously distributed.
Newtons Wissenschaftslehre als Basis der Quantenphysik
Authors: Bopp Fritz 
Published: May 2007

AbstractEs ist richtig zu sagen, die Quantenphysik folge nicht aus der auf Newtons Prinzipien beruhenden klassischen Physik. Es ist aber auch richtig, daß Newtons Wissenschaftslehre, die eng mit der Platonschen zusammenhängt und über diese hinausgeht, von der Quantenphysik nicht berührt wird, wie an anderer Stelle gezeigt ist. Hier wird Newtons Wissenschaftslehre genauer analysiert und der Unterschied zur kartesischen herausgearbeitet, was durch die Newtontradition verschleiert wird. Am Ende werden die Ergebnisse an Beispielen aus der Quantenoptik erläutert.