bluuebunny/crossref_metadata_2025 huggingface dataset:
Gekoppelte molekulare Umlagerungen als Ursache von Relaxation und Fließen
Authors: Holzmüller W.
Published: May 2007

Relaxation und Fließen beruhen auf molekularen Umlagerungen, wobei strukturbedingte Haftstellen gekoppelte Platzwechsel verursachen. Das Verhalten wird durch ein System simultaner Differentialgleichungen beschrieben. Je nach den Anfangs‐ und Randbedingungen treten unterschiedliche in einer Tabelle zusammengefaßte Lösungen auf.
Lebensdauermessungen an Resonanzzuständen im 28Si‐Compoundkern mittels Schatten‐Effekt
Authors: Otto G. , Zschau E. , Al‐Khafaji A.
Published: May 2007

Unter Anwendung des Schatten‐Effektes und der Resonanzreaktion 27Al(p, α) 24Mg an einkristallinen, dicken Al‐Targets wurden für drei Resonanzenergien Ep(keV) die Lebensdauern τ(as) der entsprechenden Anregungszustände E★ (MeV) des Compoundkernes 28Si gemessen und die zugehörigen Breiten γ(eV) berechnet: magnified image Als Target dienten 〈110〉‐orientierte Al‐Einkristalle. Die Registierung der α‐Teilchen erfolgte mit großflächigen Festkörperspurdetektoren. Aufgenommen wurden die Winkelverteilungen der α‐Teilchen um zwei 〈110〉‐Achsen des Al‐Targets, die zur Einschußrichtung der Protonen unter 75° bzw. −165° einjustiert waren. Zur Auswertung wurden die Differenzen der Minimumausbeuten Δxmin = xmin (ϕ = 75°) ‐ xmin (ϕ = −165°) und die Verhältnisse der Dip‐Volumina R = ΩE(ϕ = 75°)/ΩN(ϕ = −165°) (bis 70% der Randomausbeute) herangezogen.
Auswertung des Kernresonanzsignals bei Austausch von Molekülen zwischen einem paramagnetischen und einem diamagnetischen Bereich
Authors: Deininger D. , Hopf K. , Winkler H.
Published: May 2007

Es wird der Einfluß des Austausches von Molekülen in paramagnetischen Oberflächensystemen auf das Kernresonanzsignal behandelt. Aus experimentell bestimmter Verschiebung und Linienbreite wird für das Zweibereichsystem ein Intervall für die paramagnetische Verschiebung berechnet. Außerdem wird der Fall diskutiert, daß im paramagnetischen Bereich eine Verteilung von Lorentzlinien vorliegt und folglich die resultierende Resonanzlinie inhomogen verbreitert ist.
Sea Level Muon Spectrum Derived from Bugaev Model Using the Primary Cosmic Ray Energy Spectrum of Grigorov et al
Authors: Das A. K. , De A. K.
Published: May 2007

In a recent paper BHATTACHARYYA has derived the pion and kaon production spectra in the atmosphere using a form of the primary nucleon energy spectrum of the measurements of GRIGOROV et al. and the interaction model of BUGAEV et al. The sea level muon spectrum derived from these meson spectra agrees with the magnetic spectrograph data of ALLKOFER et al. and AYRE et al.

In this report a critical analysis of the paper has been made and some obvious mistakes in the formulation have been pointed out. The formulation of BUGAEV et al. and the data of GRIGOROV at al. have been misinterpreted by BHATTACHARYYA. The corrected results have been properly interpreted in this report.
Ein statistisches Modell zum Einfluß der thermischen Bewegung auf NMR‐Festkörperspektren
Authors: Ploss W. , Freude D. , Pfeifer H. , Schmiedel H.
Published: May 2007

Es wird ein statistisches Modell zum Einfluß der thermischen Bewegung auf die NMR‐Linienform vorgestellt, das die Verschmälerung von Festkörper‐Spektren bei wachsender Temperatur beschreibt. Das Modell geht von der Annahme aus, daß nach einer Ortsveränderung eines Kerns infolge thermischer Bewegung jede beliebige Kernresonanzfrequenz mit der durch das Festkörperspektrum vorgegebenen Wahrscheinlichkeit angenommen werden kann. Am Beispiel der Festkörper‐Gaußlinie wird der Unterschied zu dem bekannten Modell von ANDERSON und WEISS verdeutlicht.
The Influence of Bound States on the Electrical Conductivity of a Partially Ionized Plasma (Born Approximation)
Authors: Röpke G.
Published: May 2007

The partially ionized plasma is described by a model Hamiltonian containing bound (localized) as well as orthogonalized free (itinerant) electron states. The equations of balance for the single particle states are given, and the correlation functions arising in the equations of balance are treatet in the Born approximation. The conductivity is obtained with the aid of the Kohler variational principle. The electron density dependence of the conductivity is presented for different values of the bound state energy level and of the temperature.
On the Summation of Non‐leading Logarithms in QCD
Authors: Dorn H. , Otto H. ‐J. , Wieczorek E.
Published: May 2007

Exploiting the relations between the expansion coefficients of Green's functions and those of β and γ functions in massless QFT, the summation up to the n‐th non‐leading logarithms is reduced to the solution of a system of linear differential equations, which in general differ from renormalization group equations. Applying this procedure to the gluon propagator the leading log approximation is modified near the mass shell by a constant factor only. Furthermore for the gluon propagator exponentiation in terms of the running coupling constant is argued to be restricted to leading logarithms.
Impact of the Vibrationally Excited States on the Macroscopic Behaviour of the Band‐like Electron Beam Discharge Plasma in H/H2‐Mixture
Authors: Winkler R. , Wilhelm J. , Krasheninnikov S. I. , Starykh V. V.
Published: May 2007

The investigation of the impact of the vibrationally excited molecules in the electronic ground state was performed by simultaneously solving a balance equation system for the main charge carriers, the H atoms, the metastable H atoms, the H2 molecules in the different vibrational states and for the power transfer of the electrons in the beam discharge mixture plasma. The balance equations for the vibrational states include in particular one‐quantum step excitation and deexcitation, electronic excitation, dissociation and ionization from each vibrational level in electron collisions as well as the finite life time of these states because of the gas transfer through the band‐like plasma. A main finding is that due to the additional impact of vibrationally excited molecules there is a marked enhancement of the resulting dissociation and ionization degree in the beam discharge plasma at medium power input from the turbulent electric field. For discharge parameters of practical interest the ionization and dissociation budget, the population of the vibrational states, the different energy dissipation processes and the energy pumping into the ladder of the vibrational states were calculated and discussed in detail.
Eine neue Methode zur Bestimmung der Rauhigkeitsautokorrelationsfunktion von optischen Oberflächen
Authors: Ponath H. ‐E. , Walther H. ‐G.
Published: May 2007

Ausgehend von einer allgemeinen Streulichttheorie wird ein Meßverfahren zur Bestimmung der Autokorrelationsfunktion von polierten Oberflächen hergeleitet. Dabei wird die Streulichtintensität in einer bestimmten Richtung in Abhängigkeit von der Streufleckgröße gemessen. Das Meßverfahren wird an einer Glasoberfläche mit unterschiedlicher Politur getestet.
The Impact of Direct Ionization by Beam Electrons on the Electron Kinetics of the Beam Discharge Plasma in Molecular Hydrogen
Authors: Winkler R. , Wilhelm J. , Krasheninnikov S. I.
Published: May 2007

In a recent paper the stationary beam plasma discharge in partially dissociated hydrogen was investigated where the electron component was described by the Boltzmann equation for a mixture of atomic and molecular hydrogen and the main heavy charged and neutral particles by balance equations. It was assumed that, via the quasilinear beam plasma interaction, the electron beam produces only the turbulent electric field whilst an additional production of plasma electrons due to direct ionization by the beam and thus a direct influence on the balances of charge carriers were neglected. Now the additional production of plasma electrons due to direct ionization by the beam is studied on the basis of a generalized Boltzmann equation but for the simpler model of a purely molecular hydrogen plasma. For experimentally obtainable values of the turbulence energy density, beam energy, beam ionization degree and electron life time the calculation of the electron energy distribution function and of the direct beam contribution to the electron particle balance shows a marked influence of the direct beam ionization with increasing degree of beam ionization.
K‐ and L‐Vacancy Production in Asymmetric 1 MeV/N Collisions of Cu and Nb Projectiles with Au and Pb Targets
Authors: Frank W. , Jaracz P. , Kaun K.‐H. , Rüdiger J. , Stachura Z. , Warczak A.
Published: May 2007

The impact parameter dependence of the 3dσ ionization has been measured for CuAu and NbAu collisions. The impact parameter and energy dependence of the K‐L vacancy sharing is discussed in terms of the DEMKOV‐MEYERHOF and NIKITIN models. The total cross sections for producing 3dσ vacancies in all the four collision systems are considered.
Über das Äquivalenzprinzip in der Wellenmechanik
Authors: Treder H.‐J.
Published: May 2007

Wir zeigen die Gültigkeit der Galilei‐Einsteinschen Prinzipien der Äquivalenz von Trägheit und Schwere in der Wellenmechanik an Hand einer Diskussion der Einsteinschen Gedanken‐Experimente.
Kovariante Quantisierung skalarer Felder im Gravitationsfeld
Authors: Kreisel Eckhard
Published: May 2007

Zur Ankopplung der Gravitation an die Quantenfeldtheorie werden ortsabhängige unitäre Transformationen betrachtet und Ableitungen eingeführt, die eine nichtintegrale Transportvorschrift für Hilbertraumzustände implizieren. Die mit den verallgemeinerten kovarianten Ableitungen gebildete Klein‐Gordon‐Gleichung für skalare Feldoperatoren läßt sich dadurch im vorgegebenen Gravitationsfeld in gleicher Weise wie die Klein‐Gordon‐Gleichung im Minkowski‐Raum quantisieren; die Zustandsvektoren werden wegabhängig. Die Gleichungen sind bildkovariant, d. h. sie haben in jedem Bild dieselbe äußere Gestalt, speziell im Heisenberg und Schrödingerbild.
Second Order Lagrangian and Angular Momentum of Scalar Field
Authors: Günther H.
Published: May 2007

The class of second order Lagrangian for the scalar field is including free divergence terms giving rise to new canonical conservation laws by means of Noethers theorem. The appearance of a spin like tensor S within angular momentum is nothing but a redefinition of orbital angular momentum. S is mainly giving a new definition of center of mass for the field, indicating that the variation for the motion of singularities is nothing but a redefinition for the motion, since the sum for the additional forces, coming from divergence part of Lagrangian, is zero. Thus, the physical content of the theory will not be affected by the divergence part of Lagrangian, is zero. Thus, the physical content of the theory will not be affected by the divergence termes; it is only an other formulation.
Effective Flavor‐changing Weak Neutral Current in the Standard Theory and Z‐Boson Decay
Authors: Mann G. , Riemann T.
Published: May 2007

We have studied the effective Zf1f2‐vertex in the Glashow‐Salam‐Weinberg theory arising from 1‐loop corrections, allowing for arbitrary fermion masses mi in the loop. We use our results to study the branching ratio of the Z‐boson decay into two different fermions.

This is of phenomenological interest if there exist yet unknown fermions with large mass which could show up at present and designed accelerators only through radiative corrections.
On the Definition of Gauge Transformations in Gauge Theory
Authors: Sardanashvily G.
Published: May 2007

The different types of gauge transformations in gauge theory are discerned and defined in fiber bundle terms. The gauge gravitation case is analysed in order to examine various versions of the gauge gravitation theory.
Das Zweikörperproblem in der quantisierten, trägheitsfreien Mechanik
Authors: Kreisel E.
Published: May 2007

Es existieren keine gebundenen Zustände des Zweiteilchensystems in der Riemann‐Machschen Quantenmechanik. Das Energie‐Spektrum ist notwendig positiv semidefinit und kontinuierlich, in Analogie zum freien Teilchen der Quantenmechanik.
Kinetic Approach to the Electrical Conductivity in a Partially Ionized Hydrogen Plasma
Authors: Schlanges M. , Kremp D. , Keuer H.
Published: May 2007

The electrical conductivity is investigated for a partially ionized hydrogen plasma, starting from a generalized quantum kinetic equation with three particle collision integrals. To take into account plasma effects, screened potentials are used. The transport cross sections of the considered two and three particle scattering processes are calculated by perturbative solution of the Lippmann‐Schwinger equations for the T‐matrices up to the second Born approximation. In connection with a mass action law the influence of the electron‐electron and the elastic electron‐atom scattering is discussed. The pressure ionization (Mott‐effect) is described by a minimum‐behaviour of the electrical conductivity.
Mass Scales and the Cosmological Coincidences
Authors: Landsberg P. T.
Published: May 2007

Theories involving the parameters h, c, G, H (in a usual notation) are considered. A huge ratio of 10120 of the mass of the universe (mu) to the smallest determinable mass m0 in the period since the big bang occurs in such theories. Five masses are here identified and interpreted between these two limits so that one has in all seven analytical expressions for masses. They form a geometrical progression m0, m0R, …, m0R6 = mu with R ≈ 1020. It is shown that this formulation is easily adapted to explain existing cosmological coincidences and to generate new ones.
On a Temporal‐Spatial Radiation Functional and its Measurement
Authors: Gase R. , Ponath H.‐E. , Schubert M.
Published: May 2007

A so‐called radiation functional of the electric field‐strength is introduced depending on time and space and on the temporal and spatial frequencies, which is applicable to the most general forms of radiation (e.g. non‐stationary, inhomogeneous, partially coherent). The time‐dependent spectrum and the specific intensity of radiation can be deduced as special forms of the radiation functional. The dispersion relations are incorporated.

The measurement of the radiation functional by means of a linear optical system followed by square‐law detectors is dealt with; for quasi‐stationary and quasi‐homogeneous radiation the measurable function is proportional to the radiation functional. The propagation of the radiation functional in space is investigated, and, as a simple example, the diffraction by a grating of nonstationary radiation is dealt with.
Symmetry Violation Caused by the Boundary Conditions for Finite Nuclei
Authors: Rotter I.
Published: May 2007

The boundary condition of a finite lifetime of most states of real nuclei as well as its influence on the symmetry properties of the nuclear forces are investigated. It is shown that this boundary condition for finite nuclei induces some symmetry violation, e.g. for the Migdal parameter g', which does not exist in nuclear matter.
On the Theory of Spontaneous Emission by a Single Atom Located in an Ideal Cavity
Authors: Paul H.
Published: May 2007

With the help of the well‐known eigenfunctions for a two‐level system coupled to a single mode of the radiation field, the correlation functions for both the atomic dipole and the electric field oscillation are calculated, in rotating‐wave approximation, for an atom emitting spontaneously into an ideal cavity. Using the Eberly‐Wódkiewicz formalism, the corresponding spectra are evaluated in the long‐time, narrow‐band detection limit. The two spectra exhibit the same Rabi splitting, but the ratio of the strengths of the two lines is significantly different, in the off‐resonance case, for the dipole and the field oscillation.
Zu Newtons Erde‐Mond‐Test von 1665/66
Authors: Richter G.
Published: May 2007

Newtons Erde‐Mond‐Test zur Frage, ob die Schwerkraft der Erde, welche frei fallenden Körpern nahe der Erdoberfläche eine Beschleunigung von g ≈ 982 cm sec−2 erteilt, bei Annahme ihrer Abschwächung mit dem inversen Quadrat der Entfernung vom Erdmittelpunkt die beim Umlauf des Mondes um die Erde entstehende Zentrifugalkraft exakt kompensiert, wird im folgenden mit neueren Beobachtungsdaten über g, die Erddimensionen sowie die astronomischen Konstanten der Mondbahn erneut diskutiert.

Bei Berücksichtigung der Störung der Mondbewegung durch die Sonne ergibt sich bereits in erster Näherung, daß das Verhältnis der Massen von Mond und Erde nahe bei 1:81 liegen muß, wenn als „mittlere Mondentfernung”︁ der konventionelle Wert 384400 km zugrunde gelegt wird.
On the Kinetic Description of Condensation in Binary Vapours
Authors: Schmelzer J. , Schweitzer F.
Published: May 2007

Based on a thermodynamic analysis and an earlier developed general growth equation for clusters of a new phase, the kinetics of growth of droplets in a binary gaseous mixture under isothermal and isobaric conditions is described. Differential equations for the time development of the mean radius of the droplets, the number of droplets, and the overall mass concentrated in the droplets are obtained. These equations describe the evolution of the system of droplets beginning after the nucleation period has finished. The equations can be easily solved numerically. For long times analytic solutions are derived. It is shown that the growth of droplets proceeds accordingly to the mechanism of Ostwald ripening.
Quantum Field Theoretic Treatment of the Casimir Effect at T > 0. Real Time Formalism — Free Field Approximation
Authors: Scharnhorst K. , Robaschik D. , Wieczorek E.
Published: May 2007

The framework of real time quantum field theory at finite temperature is generalized to include boundary conditions for the electromagnetic field strength tensor. In the perturbation theory the usual Feynman rules remain, only the photon propagator is modified. As a first application the Casimir effect is studied in the free field approximation and the known results are rederived with the new method.
Anomalous Dimensions of Flavour Singlet Light‐cone Operators
Authors: Braunschweig Th. , Geyer B. , Robaschik D.
Published: May 2007

The anomalous Dimensions of the nonlocal flavoursinglet operators are calculated. Their relation to the local anomalous dimensions is given.
On Self Energy and Vertex Corrections to the Electrical Conductivity of Plasmas
Authors: Blümlein J. , Kraeft W. D.
Published: May 2007

In the framework of linear response theory the density correction O(n1/2 ln n) to the electrical conductivity of a nondegenerate Coulomb plasma due to equilibrium correlations is calculated.
Principles of Quaternionic Vacuum Thermodynamics and a Unified Gravistrong Interaction Model
Authors: Scheurich H.
Published: May 2007

The conceptions of the preceding paper [1] are completed by the discussion of first outlines of quaternionically originated vacuum thermodynamics. Thereby the algebraic Planck scale discontinuum statistically and approximately is extended by steps to affinely unconnected and to affinely connected Riemannian spacetime continuum. There results the concept of an irreversible particle realization process out of vacuum, as well as a vacuum foundation of the gauge principle and of the long‐range coupling constants. The version of the Electroweak Standard Model derived from the simple‐regularSO(3,3) representations is extended to a unified interaction model of gravitation and strong forces (gravistrong interaction model) derived from the double‐regularSO(3,3) representations. AnSO(3,3)‐originated connection between the linear graviton field and the non‐linear gravitation field is proposed.
On Internucleon Interaction of Composite Nucleon
Authors: Kim D. Y.
Published: May 2007

We discuss the low energy nucleon‐nucleon interaction leading to a bound state, namely the deuteron problem. The currently known method of calculating internucleon interactions is the boson exchange potential model, where the Klein‐Gordon equation for a virtual pseudoscalar boson with a single point‐like nucleon source is solved using the Green function method. This method is known to be inadequate in particular to the internucleon problem leading to a bound state. As an alternative we propose to solve internucleon potential problems, including the bound state, by solving the Klein‐Gordon equation in which the interaction term has been introduced in a more invariant way. In the place of the single source term used in the standard method the interaction term is introduced in the covariant derivative form in the spirit of the minimum coupling scheme. It turns out that this method is not only mathematically satisfactory (gauge and Lorentz invariant formalism aspect), but also gives a more physically satisfactory interpretation of the internucleon interaction mechanism. For a deuteron bound state problem can then be solved approximately using the variational calculus. We obtain the analytic expression for the internucleon potential as a function of internucleon distances. The minimum energy value 2,2 MeV, the binding energy of the deuteron, is found to be at equilibrium distance of rab = ϱφ = 2 × 10−13 cm.
Thermodynamics of Systems of Non‐Equilibrium Momentum Distribution
Authors: Lukács B. , Martinás K.
Published: May 2007

There exist physical processes (e. g. in energetic heavy ion collisions), where the time scale of the process is not sufficiently long to reach complete thermal equilibrium. Here we show a way to extend the thermodynamical formalism for unequilibrium situations. The results are compatible with continuum mechanics.
Angular Gamma Dose Rate Distribution at the Surface of Injected Ducted Concrete Shield
Authors: Ahmed Fikria M. Sayed , Abboud Aida
Published: May 2007

The shielding problems that arise due to the irregular penetrations such as neutral beam injection ducts should be treated carefully to aid in the shield design. The present work was undertaken to describe the effects arising due to radiation streaming through the neutral beam injector ducts (NBID) on the angular distribution of the total gamma ray doses at the outer surface of illmenite concrete shield (ϱ = 4.6g/cm3). The shield is pierced with NBID of different diameters and lengths.

The measurements were performed using a collimated beam of both gamma rays and neutrons emitted from one of the horizontal channels of the ET‐RR‐1 reactor. The measurements were carried out using 7LiF teflon thermoliminescent dosimeters. Generally the obtained data reveal that the presence of the total dose increase at the centerline of NBID and which in turn tends to decrease with the increase of scattered angle. An empirical formula describing the differential dose rate ratio is predicted. The experimental data obtained reveal good agreement with the calculated ones.
Max Planck prüft und verbessert
Authors: Thiessen Peter Adolf
Published: May 2007

Vor 50 Jahren besuchte der scheidende Präsident der Kaiser Wilhelm Gesellschaft, Max Planck, das Kaiser Wilhelm Institut für Physikalische Chemie in Dahlem, dessen Direktor Prof. P. A. Thiessen war.
Planck's Orders of Magnitude and the Limits of the Quantum Gravity Conception
Authors: v. Borzeszkowski H.‐H.
Published: May 2007

Considering gravitational Euler scattering and energy fluctuations of gravitational Planck radiation it is shown that ‐ due to the nonlinearity of Einstein's equations ‐ there arise effective cut‐of lengths preventing the measurability of quantum vacuum effects near Planck's length.
The Formalism of Quantum Theory: An Objective Description of Reality?
Authors: Dieks D.
Published: May 2007

We argue that the formalism of quantum theory can be given an empirical interpretation (in the sense of a connection with observable phenomena) in the same way as in any other empirical theory. In particular, there is no need to supplement the unitary time evolution governed by a Schrödinger‐type of equation with a “projection postulate” that applies only to measurements. As a consequence, the quantum formalism has the same status as the formalisms of older physical theories, and is capable of the same philosophical interpretations. The most natural interpretation, we argue, is to conceive of the formalism as an objective – although highly abstract – description of reality.
Quantum Restrictions on Measurement of Electromagnetic Field
Authors: Mensky M. B.
Published: May 2007

The integration over field configurations is applied for finding quantum restrictions on measurability of electromagnetic field strength. The inequalities are derived demonstrating what precision is available for estimation, with the help of measurements, of the field strength in each point of a spacetime region. The comparison is made of the obtained results with those of the known papers by Landau and Peierls and Bohr and Rosenfeld.
Fast Neutron Albedo Calculations for a Concrete Shield with Different Curvatures
Authors: Ahmed F. M. Sayed , Salama M.
Published: May 2007

The O5R Monte Carlo neutron transport Code had been used to calculate the neutron albedo for neutrons reflected from plane and curved concrete shields. The present calculations were performed to investigate the fast‐neutron albedo in case of ordinary concrete shield, in order to perform comparative studies with the case of neutron reflection against a flat wall. The calculations were performed for three different neutron source energies of 1 MeV, 5 MeV and 15 MeV and at neutron incident angles of 5°, 30°, 45°, 60° and 90° and for surfaces with different curvatures (flat, 100, 50, 20 and 5 cm).

The results obtained reveal that there will be an appreciable error on using the flat wall albedo value in the case of duct penetration calculations. The error was assumed to be due to the neglection of the curvature effect as well as to the improper choice of the neutron incident angle.
On the Relation between Effective Potentials and Realistic Potentials
Authors: Hassan M. Y. M. , Moharram S. , Al‐Halmoushi G. M.
Published: May 2007

A velocity dependent effective potential of s‐ and p‐wave interaction denoted by VG2 has been applied to calculate the parameters of nuclear matter. Using this potential, the binding energy of a group of double closed shell nuclei is calculated according to the shell model. Also, the binding energy of 12C and 16O is calculated assuming Brink's model and using the VG2 interaction together with the potential deduced by Arickx et al. Reasonable agreement with experimental data is obtained.
Verfahren zur hochgenauen Bestimmung des Reflexionsvermögens von Laserspiegeln in einer Resonatoranordnung
Authors: Fiedler Roland , Schirmer Gustav , Schubert Dieter , Walther Heinz‐Günter
Published: May 2007

Wird auf geeignete Weise ein hochfrequent amplitudenmodulierter Laserstrahl geringer Linienbreite in einen passiven Resonator gekoppelt, bewirken die Resonatorgeometrie und die ReflexionsvermögenR1undR2der Resonatorspiegel eine Phasenverschiebung des Modulationssignales bezüglich eines Referenzstrahles.

Durch zeitlineare Resonatorlängenänderung wird eine zeitabhängige Phasenverschiebung erzeugt, der das ProduktR1R2eindeutig zu entnehmen ist.
Studies on Thermal Neutron Backscattered by Neutral Beam Injector Ducts in Concrete Shield
Authors: Ahmed F. M. Sayed
Published: May 2007

Experimental studies on the angular flux distributions of backscattered thermal neutrons by neutral beam injector ducts (NBID) in ilmenite concrete are performed. The neutron flux distributions have been measured at the end of the ducted assembly and perpendicular to the duct axis by means of Indium thermal detector. The experimental facility and the detector activity measurement techniques are described. Results concerning injector ducts with different diameters are graphically represented. Calculations to analyse the experimental results are given.
Sketch of a New 5‐dimensional Projective Unified Field Theory — Physical Predictions and Applications
Authors: Schmutzer E.
Published: May 2007

Some years ago the author published a new version of a 5‐dimensional Projective Unified Field Theory unifying gravitation, electromagnetism and scalarism. Geometrically this theory is mainly based on following 5‐dimensional assumptions: symmetric metric tensor, Riemannian curvature, torsion, projector property of the basic quantities. A particular projection procedure leads from the 5‐dimensional field equations and conservation laws to 4‐dimensional ones. The 4‐dimensional scheme of equations is interpreted physically. Special interest is taken in the energy projector, describing an electrically charged perfect fluid. Several physical predictions and applications are presented.
Klein Gordon Equations on a Time Lattice
Authors: Hamdan N. , Uhlmann A.
Published: May 2007

We consider the second quantization procedure for a KLEIN GORDON equation with time dependent Hamiltonian and with replaced second order time derivative by the appropriate difference operator. With each time step there is a Bogoljubov transformation which describes particle creation and annihilation and the accompanied change of the Fock vacuum.
Quantum Statistics of the Toda Oscillator in the Wigner Function Formalism
Authors: Vojta Günter , Vojta Matthias
Published: May 2007

Classical and quantum mechanical Toda systems (Toda molecules, Toda lattices, Toda quantum fields) recently found growing interest as nonlinear systems showing solitons and chaos. In this paper the statistical thermodynamics of a system of quantum mechanical Toda oscillators characterized by a potential energy V(q) = Vo cos h q is treated within the Wigner function formalism (phase space formalism of quantum statistics). The partition function is given as a Wigner‐ Kirkwood series expansion in terms of powers of h2 (semiclassical expansion). The partition function and all thermodynamic functions are written, with considerable exactness, as simple closed expressions containing only the modified Hankel functions Ko and K1 of the purely imaginary argument iζ with ζ = Vo/kT.
Atomic force microscopy at MHz frequencies
Authors: Rabe U. , Arnold W.
Published: May 2007

Cantilevers of atomic force microscopes usually have spring constants of less than 1 N/m and fundamental resonance frequencies for free vibration between 10 and 100 kHz. If, however, the tip is in contact with the surface of a sample vibrating at MHz frequencies, we have observed that the cantilever can be forced to vibrate also at these high frequencies with high amplitude. For the detection of the high frequency vibrations of the cantilever we added in our experiment a fast optical knife‐edge detector to a commercial Atomic Force Microscope. Ultrasonic pulses were excited by a piezoelectric transducer bonded to the sample and the ultrasonic signals transmitted to the cantilever were recorded. Furthermore, the vibrational amplitude of the cantilever was measured locally along the cantilever. For comparison we also measured the absolute surface amplitude by a Michelson‐heterodyne interferometer. The spectral components of the cantilever vibration were examined and discussed theoretically.
Vacuum Kerr‐Schild metrics generated by nontwisting congruences
Authors: Gergely László Á. , Perjés Zoltán
Published: May 2007

The Kerr‐Schild pencil of metrics gab = gab + Vlalb, with gab and gab satisfying the vacuum Einstein equations, is investigated in the case when the null vector l has vanishing twist. This class of Kerr‐Schild metrics contains two solutions: the Kasner metric and a metric which can be obtained from the Kasner metric by a complex coordinate transformation. Both are limiting cases of the Kóta‐Perjés metrics. The base space‐time is a pp‐wave.
Phonon diffraction gratings
Authors: Vu P. D. , Olson J. R. , Pohl R. O.
Published: May 2007

A two‐dimensional diffraction grating for phonons is described. It scatters thermal phonons strongly when their dominant wavelength is equal to the grating's lattice constant. Through measurements of the Kapitza resistance between the silicon crystal carrying the grating and liquid helium, it is shown that the scattering by the grating is predominantly coherent, as expected for phonon diffraction.
Chaotic cryptology
Authors: Martienssen W. , Hübinger B. , Doerner R.
Published: May 2007

A method to transfer secret information using chaotic dynamical systems is proposed. It is based on modulating a chaotic system with the message such that its time evolution contains the hidden information. Decryption of the cipher is achieved by chaos control. Operation of the scheme is demonstrated by en‐ and decoding a short german text.
Phonon heating of two‐dimensional exciton gases in GaAs/AlGaAs quantum wells
Authors: Moskalenko E. S. , Zhmodikov A. L. , Akimov A. V. , Kaplyanskii A. A. , Challis L. J. , Cheng T. , Hughes O. H.
Published: May 2007

We report the first measurements of the interaction of non‐equilibrium phonons with two‐dimensional exciton gases (2DExGs). The rise in the effective temperature of the 2DExG produced by the phonons depends on the width of the quantum well and the exciton sheet density and hence on the ratio τ−1 (ex‐ph)/τ−1 (ex‐ex). The dependence of the effective temperature rise on this ratio is attributed to the non‐equilibrium frequency distribution of the phonons incident on the 2DExG.
Microwave oscillator based on Bloch oscillations of electrons in a semiconductor superlattice
Authors: Grenzer J. , Ignatov A. A. , Schomburg E. , Renk K. F. , Pavel'ev D. G. , Koschurinov Yu. , Melzer B. , Ivanov S. , Schaposchnikov S. , Kop'ev P. S.
Published: May 2007

We report on a microwave oscillator based on Bloch oscillations of electrons in a semiconductor superlattice. Our GaAs/AlAs superlattice, at room temperature, was coupled electromagnetically by an antenna to a rectangular cavity resonator, and was operated at a current‐voltage state of negative differential conductance. We observed generation of microwave radiation at frequencies, depending on the resonator length, between 7 and 30 GHz. Electronic tuning by several percent was possible; the ratio of linewidth to frequency was of the order of 10−4. A radiation power up to 1 μW (at 10 GHz) was obtained, corresponding to a generator efficiency of the order of 10−3 for the conversion of electrical power to microwave radiation.
Ferromagnetism in the Hubbard model: instability of the Nagaoka state on the triangular, honeycomb and kagome lattices
Authors: Hanisch Thoralf , Kleine Burkhard , Ritzl Afra , Müller‐Hartmann Erwin
Published: May 2007

In order to analyse the lattice dependence of ferromagnetism in the two‐dimensional Hubbard model we investigate the instability of the fully polarised ferromagnetic ground state (Nagaoka state) on the triangular, honeycomb and kagome lattices. We mainly focus on the local instability, applying single spin flip variational wave functions which include majority spin correlation effects. The question of global instability and phase separation is addressed in the framework of Hartree‐Fock theory. We find a strong tendency towards Nagaoka ferromagnetism on the non‐bipartite lattices (triangular, kagome) for more than half filling. For the triangular lattice we find the Nagaoka state to be unstable above a critical density of n = 1.887 at U = ∞, thereby significantly improving former variational results. For the kagome lattice the region where ferromagnetism prevails in the phase diagram widely exceeds the flat band regime. Our results even allow the stability of the Nagaoka state in a small region below half filling. In the case of the bipartite honeycomb lattice several disconnected regions are left for a possible Nagaoka ground state.
Noise induced transport
Authors: Mielke Andreas
Published: May 2007

We study the overdamped motion of a particle in a one‐dimensional periodic potential driven by a stochastic force. If the stochastic force is correlated in time (non‐white), and if the potential has no inversion symmetry, a current is generated. In the case of a piecewise linear potential we obtain a closed expression for the current as a ratio of two determinants. This allows us to calculate the current as a function of the noise strength, the correlation time and the temperature of the system for several stochastic processes. We examine several limiting situations. Depending on the statistics of the noise process, the direction of the current may change. Two different mechanisms for this effect are discussed.
The dynamics of disordered systems and the motion of vortices in disordered type‐II superconductors
Authors: Müllers J. , Schmid A.
Published: May 2007

We develop a field theoretical method which permits us to study the dynamics of interacting particles in disordered systems. In particular, making use of a Hartree‐type approximation, we obtain a self‐consistent system of equations for disorder averaged quantities. The method is first applied to a single particle on a rough surface. Then, we calculate the current‐voltage (I‐V) characteristics of a type‐II superconductor in the flux flow regime. Finally, the structure of the steps is discussed which arise in the I‐V‐characteristics when a small ac field is superimposed on the constant voltage. These may serve as a probe for incipient melting of the vortex lattice.
Spin‐fluctuation gating in the c‐axis non‐Drude conductivity of the high Tc cuprates
Authors: Mukhin Sergei I. , Kyung Bumsoo , Ferrell Richard A.
Published: May 2007

An ideal antiferromagnetic (AF) ordering of the spins of the CuO layers of an underdoped cuprate prevents the low energy tunneling of the charge carriers between the layers. In order to obtain a non‐vanishing c‐axis conductivity (σc), we invoke ground state fluctuations of the spin system. These provide a frequency‐dependent gating effect by changing the direction of the AF order parameter within one layer relative to that in a neighboring layer, thereby permitting some tunneling. The calculated σc compares favorably with experimental data in a) being small and b) having a weak frequency dependence of distinctly non‐Drude form.
Effect of Prolactin and Bromocriptine on the Population of Prostate Neuroendocrine Cells from Intact and Cyproterone Acetate‐Treated Rats: Stereological and Immunohistochemical Study
Authors: Ingelmo Ildefonso , Gómez Vicente , Martín Rocio , Codesal Javier , Rodríguez Rosario , Pozuelo Jose M. , Santamaría Luis
Published: May 2007

This work deals with the quantification of serotonin‐immunoreactive prostate neuroendocrine cells (NECs) in rats exposed to prolactin in normal, cyproterone acetate‐exposed, and bromocriptine‐exposed animals to establish the possible influence of prolactin with or without androgenic blockade on this cell population. Thirty male peripubertal Sprague‐Dawley rats were grouped as controls (CT) and those treated with cyproterone acetate (CA), cyproterone acetate plus prolactin, cyproterone acetate plus bromocriptine, prolactin (PL), and bromocriptine (BC). The volume of ductal epithelium (Vep) and total number (NSER) of the NECs serotonin‐immunoreactive were measured. NECs were detected in the periurethral ducts. Compared to CT, Vep was increased in PL and BC and NSER was decreased in CA and increased in the prolactin or bromocriptine groups. The androgenic blockade decreases NSER in rat prostate; PL induces in normal and cyproterone acetate‐treated rats the increase of NSER; and BC exerts a local effect over the prostate similar to that described for PL. Anat Rec, 2007. © 2007 Wiley‐Liss, Inc.
Characterization of Deltoid, a chimeric protein containing the oligomerization site of hepatitis delta antigen
Authors: Saderholm Matthew J. , Lemon Stanley M. , Erickson Bruce W.
Published: May 2007

Both forms of the hepatitis delta antigen (HDAg) encoded by hepatitis delta virus are active only as oligomers. Previous studies showed that quadrin, a synthetic 50‐residue peptide containing residues 12–60 from the N‐terminus of HDAg, interferes with HDAg oligomerization, forms an α‐helical coiled coil in solution, and forms a novel square octamer in the crystal consisting of four antiparallel coiled‐coil dimers joined at the corners by hydrophobic binding of oligomerization sites located at each end of the dimers. We designed and synthesized deltoid (CH3CO‐[Cys23]HDAg‐(12‐27)‐seryl‐tRNA synthetae‐(59‐65)‐[Cys42]HDAg‐(34‐60)‐Tyr‐NH2), a chimeric protein that structurally resembles one end of the quadrin dimer and contains a single oligomerization site. The 51‐residue chain of deltoid contains a seven‐residue α‐hairpin loop in place of the remainder of the quadrin dimer plus Cys12 and Cys31 for forming an intrachain disulfide bridge. Reduced, unbridged deltoid (Tm = 61°C, ΔG(H2O) = −1.7 kcal mol−1) was less stable to denaturation by heat or guanidine HCl than oxidized, intrachain disulfide‐bridged deltoid (Tm > 80°C, ΔG(H2O) = −2.6 kcal mol−1). Each form is an α‐helical dimer that reversibly dissociates into two monomers (Kd = 80 μM). © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 764–773, 2007.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Über Diaroylhydrochinone, III. Mitteilung
Authors: Pummerer Rudolf , Buchta Emil , Deimler Edith
Published: May 2007

Die leicht zugängliche Hydrochinon‐dicarbonsäure‐(2.5) ließ sich nach Acetylierung und Umwandlung in das Chlorid einer doppelten Friedel‐Crafts‐Synthese unterwerfen, nach der wie früher beschrieben 2.5‐Dibenzoyl‐, Ditoluyl‐ und Dixyloyl‐hydrochinon dargestellt worden sind.
Phenanthrensynthesen über intraionische Isomerisationen
Authors: Wittig Georg , Davis Pauls , Koenig Günter
Published: May 2007

Das 9‐Benzyl‐phenanthren wurde auf dem Wege einer intrakationischen Isomerisation und das Phenanthren selbst über eine intraanionische Umlagerung hergestellt.
Crataegolsäure, ein neues Triterpenoid aus Crataegus oxyacantha. Ein Beitrag zur Konstitution der α‐Amyrine
Authors: Tschesche Rudolf , Fugmann Robert
Published: May 2007

Als Hauptbestandteil der sog. „Crataegussäure”︁ bzw. des „Crataeguslactons”︁ wurde eine Triterpenoid‐carbonsäure C30H48O4 erkannt, die den Namen „Crataegolsäure”︁ erhielt und als eine 2.19‐Dioxy‐Δ13,18‐ursan‐carbonsäure‐(17) angesehen wird. Sie stellt ein durch Kristallisation nicht trennbares Gemisch der beiden in Bezug auf die Oxygruppe an C19 epimeren Säuren dar. Die Annahme einer sekundären Oxygruppe an C19 epimeren Säuren dar. Die Annahme einer sekundären Oxygruppe an C19 zwingt zu einer Änderung der bisherigen Formel für die α‐Amyrine die nunmehr mit einer geminalen Anordnung von 2 CH3‐Gruppen an C20 wie in den β‐Amyrinen und mit einer Doppelbindung Δ13,18 formuliert werden. Es werden die bisherigen Versuchsergebnisse an α‐Amyrin‐Derivaten in Bezug auf die neue Formel diskutiert.
Über Einschlußverbindungen, II. Mitteil. Die blauen Jodadditionsverbindungen organischer Moleküle
Authors: Cramer Friedrich
Published: May 2007

Die blauen Jodadditionsverbindungen vom Typ der Jodstärke sind Einschlußverbindungen, in deren molekularen Hohlräumen Kanäle verlaufen, in denen sich Jodketten über größere Bereiche erstrecken. Die Jodatome besitzen einen Abstand von 3.06 Å; die ganze Kette bildet eine Resonanzeinheit. Makromoleküle bilden die Verbindung schon in Lösung, kleinere Moleküle erst beim Ausbilden eines Kristallgitters.
Konstitution und Lichtabsorption, IV. Mitteil.: Dicarbonyl‐Derivate
Authors: Bohlmann Ferdinand
Published: May 2007

Es werden die Absorptionsspektren von Dicarbonyl‐Derivaten, insbesondere von Chinoxalinen, untersucht. Die sich auf Grund theoretischer Überlegungen und durch Vergleich mit entsprechenden chromophoren Systemen ergebenden Deutungsmöglichkeiten werden diskutiert.
Coniferyl‐methyläther und andere mit dem Lignin zusammenhängende Stoffe
Authors: Freudenberg Karl , Bittner Friedrich
Published: May 2007

Der dem Cinnamyl‐methyläther entsprechende Coniferyl‐methyläther wird beschrieben. Er liefert Polymerisate mit Dehydrogenasen und mit Säuren. Zwischenprodukte für die Synthese von Modellsubstanzen des Lignins wurden dargestellt.
Über Isonitrilkomplexe, III. Mitteil.: Isonitrile und Friedel‐Crafts‐Katalysatoren
Authors: Klages Friedrich , Mönkemeyer Karl
Published: May 2007

Bei der Einwirkung von Friedel‐ Crafts‐Katalysatoren Isonitrile beobachtet man keine Komplexbildung mehr, sondern eine außerordentlich starke Erhöhung der Polymerisationsneigung der Isonitrile. Dieses unerwartete Verhalten wird durch Angriff des Komplexbildners auf den Isonitrilstickstoff gedeutet.
2 ‐ Desoxy ‐ d‐ xylose aus d‐Glucose über 3‐Desoxy‐d‐galaktose
Authors: Weygand Friedrich , Wolz Hans
Published: May 2007

1.2; 5.6‐Diisopropyliden‐3‐tosyl‐d‐glucose läßt sich über 1.2; 5.6‐Diisopropyliden‐3‐desoxy‐glucoseen‐(3), 1.2; 5.6‐Diisopropyliden‐3‐desoxy‐d‐galaktose, 3‐Desoxy‐d‐galaktose und 3‐Desoxy‐d‐galaktoseoxim in 2‐Desoxy‐d‐xylose überführen. Der Abbau des Oxims wurde mit 4‐Fluor‐1.3‐dinitro‐benzol vorgenommen.
Über partielle Racemate, IV. Mitteil.: Verbindungen von cis‐ und trans‐Tetralindiol‐(2.3)
Authors: Lettré Hans , Lerch Irmgard
Published: May 2007

Die von Leroux beschriebene Molekülverbindung aus racem. trans‐ und cis‐Tetralindiol‐(2.3) wurde näher untersucht. Auch die optischen Antipoden der trans‐Form bilden mit der cis‐Form Molekülverbindungen 1 : 1; als Verbindungen diastereomerer Formen sind diese als partielle Racemate aufzufassen. Die von Leroux beschriebene Verbindung ist ein Mischkristallisat aus den beiden partiellen Racematen.
Über neue Bestandteile des Steinkohlenteer‐Pechs
Authors: Kruber Otto , Oberkobusch Rudolf
Published: May 2007

Aus der um 470° siedenden Pechfraktion des Steinkohlenteers wurden zwei neue Verbindungen abgeschieden und als 3.4‐Benzofluoranthen und 1‐Oxo‐1.2‐dihydro‐2‐aza‐pyren gekennzeichnet.
Über Dehydro‐tetrachlor‐p‐kresol, ein Radikal mit einwertigem Sauerstoff; XI. Mitteil. über die Oxydation der Phenole
Authors: Pummerer Rudolf , Schmidutz Georg , Seifert Helmut
Published: May 2007

Die Lösungen von Dehydro‐tetrachlor‐p‐kresol zeigen keine Disproportionierung zu Chinonmethid und Tetrachlor‐p‐kresol, enthalten daher, da die Disproportionierung nicht als Erklärung für die doppelte Gefrierpunktserniedrigung herangezogen werden kann, etwa zu 90% freie Radikale. Diese reagieren mit Trityl, Dimethylbutadien und Cyclopentadien unter Anlagerung des Tetrachlor‐kresoxyls, eines Radikals mit einwertigem Sauerstoff, an den Kohlenstoff. In konz. Lösungen tritt zu über 90% Umlagerung zum Oktachlor‐diphenoläthan ein. Die hell citronengelbe feste Substanz entfärbt sich beim Lagern im Dunkeln, ohne daß die Radikaleigenschaften verschwinden.
Über 3.4‐Dioxy‐kynurenin, seine Synthese und physiologische Bedeutung
Authors: Butenandt Adolf , Schlossberger Hans‐Georg
Published: May 2007

d,l‐3.4‐Dioxy‐kynurenin wurde nach dem Prinzip der 3‐Oxy‐kynurenin‐Synthese von A. Butenandt und G. Hallmann synthetisiert. Es ist unter den Bedingungen der üblichen Standardteste 1.) unwirksam im Augenpigment‐Bildungsprozeß an Drosophila und Ephestia und vermag 2.) bei Neurospora crassa Nicotinsäureamid nicht zu ersetzen. Nach diesen Ergebnissen kann 3.4‐Dioxy‐kynurenin weder als Zwischenprodukt der Ommochrom‐ noch der Nicotinsäure‐Synthese aus Tryptophan angesprochen werden. Das Enzym Kynureninase (nach O. Wiss aus Ratten‐ bzw. Schweineleber) spaltet 3.4‐Dioxy‐kynurenin in Alanin und 3.4‐Dioxy‐anthranilsäure; da dieses Enzym auch in Neurospora nachweisbar ist, stellt somit auch 3.4‐Dioxy‐anthranilsäure kein Zwischenprodukt der Nicotinsäure‐Synthese aus Tryptophan dar.
Synthese hypericinähnlicher Oxy‐meso‐ naphthodianthrone II. Mitteilung
Authors: Brockmann Hans , Dorlars Alfons
Published: May 2007

Die 2.2′‐ und 3.3′ ‐Dimethyl‐Derivate des 4.4′‐Dioxy‐helianthrons und 4.4′‐Dioxy‐meso‐naphthodianthrons wurden dargestellt. Die sterische Hinderung der 2.2′ ‐Methylgruppen wirkt in den meisten Lösungsmitteln schwach bathochrom. Aus den Eigenschaften der neuen Verbindungen läßt sich schließen, daß die — verglichen mit 4.5.4′.5′ ‐Tetraoxy‐meso‐naphthodianthron — langwelligere Absorption und größere Löslichkeit des Hypericins hauptsächlich durch dessen 2.2′ Methylgruppen bedingt ist.
β‐Aminosäuren, I. Mitteil.: β‐Amino‐pimelinsäure
Authors: Birkofer Leonhard , Storch Ingeborg
Published: May 2007

Es wird die Darstellung der β‐Amino‐pimelinsäure durch Reduktion des β‐Keto‐pimelinsäurediäthylester‐acetylhydrazons beschrieben.