Der Einfluss von Beimengungen auf die Fasersubstruktur von Zink-Einkristallen

Zusammenfassung An Einkristallen von Zn mit Beimengungen von Cd oder Cu wurde experimentell die Abhä agigkeit der Größe des Durchmessers der Fasersubstruktur vom Gehalt der Beimengungen untersucht, die aus der Theorie von Rutter und Chalmers [1] hervorgeht. Es wird die Möglichkeit gezeigt, die Größe des Verteilungskoeffizientenk aus den erzielten Ergebnissen abzuschätzen.

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Der Einfluss von Fremdstoffgehalt auf einige Kenngrössen der Verfestigungskurven von Zinkeinkristallen

Zusammenfassung Es wurde der Einfluß von Fremdstoffgehalt: auf die kritische Schubspannung ₀, den Verfestigungskoeffizient _A im BereichA der Verfestigungskurve; die Längea _A des BereichsA, und die Schubspannung _A am Ende des BereichsA, von Zinkeinkristallen untersucht. Es konnte gezeigt werden, daß der Einfluß von Fremdstoffgehalt auf den Wert der kritischen Schubspannung vorwiegend indirekter Natur ist. Die Abnahme des Verfestigungskoeffizienten mit zunehmendem Fremdstoffgehalt kann an Hand erhöhter Leerstellenkonzentration erklärt werden. Das Auftreten des BereichsB wird im Zusammenhang mit der Entstehung von Frankschen Halbversetzungen erwogen.

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₀, _A , _A . , . . .

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Herrn P. Sirotek bin ich für den Umbau und die Instandsetzung des Polanyiaparates zu Dank verpflichtet. Mein Dank gehört ferner Herrn J. Voráek, für die präzise Durchführung der polarographischen Analysen, Frau I. Ejemová und M. Postránecká, für die Verrichtung der Orientierungsbestimmungen und Rechenarbeiten. Gleichzeitig möchte ich Frl. Svobodová meinen herzlichen Dank aussprechen — sie hat, auf Anregung des Lehrstuhls für mathematische Statistik an der mathematisch-physikalischen Fakultät der Karlsuniversität in Prag, mit großem Verständnis die statistische Auswertung der Meßergebnisse durchgeführt. Herrn Dr. F. Kroupa und Ing. B. esták bin ich für das Durchlesen des Manuskripts sowie wertvolle Hinweise zu Dank verpflichtet. Mein besonderer Dank für zahlreiche fruchtbare Diskussionen und Anregungen gilt Herrn P. Kratochvíl. Herrn Prof. Dr. A. Seeger danke ich ganz besonders für Kritik des Manuskripts und wertvolle Ratschläge.     

Photon scattering on quasi-free neutrons in the reaction γd→γ′np and neutron polarizabilities

The possibility to obtain information on n scattering at intermediate energies from the reaction dnp is analyzed. To this aim, the differential cross sectiond ³ /d ,d _n dE _n and the scattering asymmetry with linearly polarized photons are calculated at photon energies 100 to 400 MeV in the diagrammatic approach. The pole diagrams of the impulse approximation are evaluated with realistic n and p scattering amplitudes. One-loop diagrams withnp rescattering in the final state and with meson-exchange and isobar currents are taken into account as well. The main contribution to the differential cross sectiond ³ /d ,d _n dE _n in the kinematics of quasi-free n scattering arises from the neutron pole diagram. The correction due to other diagrams is typically –30% to –10% and decreases with increasing photon energy and momentum transfer. The sensitivity of the cross sections to the magnitude of the neutron electric polarizability and to the sign of the ⁰2 decay constant is demonstrated.     

К изучению пространс тв между электродами в кратковременных эл ектрических разряда х с болъшой силой тока

, . . , . , , , .

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A contribution to the study of electrode spaces of high-current short-duration electric discharges

The electrode spaces of high-current short-duration discharges are analyzed using the method of artificial contraction (limiting of the active surface of the electrodes). It was shown that evaporation of the electrodes during the discharge can be regarded as one of the main factors causing thermal contraction of the channel on the surface of electrodes, high-current density on the electrodes and enabling the independent existence of partial spots.

     

ПРИМЕНЕНИЕ ПАРАМАГН ИТНОГО РЕЗОНАНСА ДЛЯ ИССЛЕДОВАНИЯ РЕАКЦИЙ СВОБОДНЫХ РА ДИКАЛОВ

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The use of paramagnetic resonance in studying the reactions of free radicals

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, .     

Theory of tamm surface states in approximation higher than tight-binding approximation

The influence of the non-zero value of exchange integrals between Wannier functions, localized in non-neighbouring elementary cells (higher approximation than tight-binding), on the conditions of existence of Tamm surface states and the position of the energy level corresponding to the surface state is shown.

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This paper is part of M. Tomáek's candidate's thesis.     

Symmetries and half-sided modular inclusions of von Neumann algebras

LetN, be a von Neumann algebras on a Hilbert space , a common cyclic and separating vector. Assume to be cyclic and also separating forN . Denote by , _N , _N the modular operators to (, ), (N, ), resp (N , ). Assume now ^-it N ^it N for allt 0. (Such type of inclusions ((N U, ) , ) are called half-sided modular.) Then the modular groups ^it , _N ^ir , _N ^is ,t, r, s generate a unitary representation of the group S1(2, )/Z ₂ of positive energy.Another result is related to two half-sided modular inclusions (₁ , ) and (₂ , ). Under proper conditions the three modular groups ^it , ₁ ^ir , ₂ ^is ,t, r, s generate the three-dimensional subgroup of O(2, 1) of two commuting translations and the Lorentz transformation.Partly supported by the DFG, SFB 288 Differentialgeometrie und Quantenphysik.     

Die Röntgenolumineszenz Von NaCl-Kristallen Mit Beimengungen Von Elementen Der Eisengruppe

Zusammenfassung Es werden Versuchsergebnisse des Studiums der Röntgenolumineszenz (RL) von NaCl-Kristallen mit Beimengungen von Elementen der Eisengruppe (Fe, Co, Ni) angeführt. Die Kristalle wurden aus der Lösung und aus der Schmelze gezüchtet. Das Vorkommen und das Höhenverhältnis der einzelnen Emissionsbanden werden diskutiert.

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NaCl

NaCl Fe, Co, Ni. . .

     

Particles and scaling for lattice fields and Ising models

The conjectured inequality ⁽⁶⁾0 leads to the existence of _d ⁴ fields and the scaling (continuum) limit ford-dimensional Ising models. Assuming ⁽⁶⁾0 and Lorentz covariance of this construction, we show that ford6 these _d ⁴ fields are free fields unless the field strength renormalizationZ ^–1 diverges. Let be the bare charge and the lattice spacing. Under the same assumptions (⁽⁶⁾0, Lorentz covariance andd6) we show that if ^4–d is bounded as 0, thenZ ^–1 is bounded and the limit field is free.Supported in part by the National Science Foundation under Grant MPS 74-13252Supported in part by the National Science Foundation under Grant MPS 75-21212     

Real-space renormalization group for directed percolation system

We use the recently proposed real-space renormalization group method to study the critical behavior of directed percolation system in two dimensions. The correlation length exponents and are found to be 1.76 and 1.15. These results are in good agreements with the best known values.     

KL,S → l+l− decays in the quark model of superconductivity type

The probabilities of K_L,S l⁺l^– decays are calculated by considering only the dominant two-lepton channel K_L,S ^{* *} l⁺l^–. The transitions K⁰ X, where X=⁰,, or (700) dominating in the K_L,S ^{* *}decay amplitudes, are described by the effective weak Lagrangian. The matrix elements of four-quark operators are calculated within the framework of the quark model of superconductivity type. It is shown that the leading contribution to matrix elements of K⁰ X transitions comes from the penguin operator matrix elements.     

Bianchi and Weyl equations as sufficient equations for Einstein spaces

When the Bianchi equation and the wave equation for the Weyl spinor are written in the form which they take for Einstein spaces, but with the symmetric 4-spinor _ABCD considered arbitrary and with the background space unspecified, ^EA _EBCD=0; (+12) _ABCD –6(AB ^EF ( _CD )EF =0 it is shown that — in general — for this pair of equations to be consistent, the background space has to be an Einstein space, and the symmetric 4-spinor _ABCD has to be the Weyl spinor of this space.     

Rate equations in the hopping transport

The usual kinetic equations for the site occupation probabilities in an external field are solved exactly in a simple one-dimensional periodic model with two kinds of atoms using a) free boundary conditions and order of limitsN, 0 needed for a proper treatment of the dc conductivity here b) boundary conditions with metallic contacts and order of limitsN, 0 and c) the same boundary conditions but reversed order of limiting processes 0,N typical of e.g. numerical and percolation treatments. (N and are the number of sites and frequency.) It is demonstrated that though the bulk dc conductivity is the same in all three cases, local bulk properties of the material are strongly dependent on the régime used. The role of the order of all three limiting processes 0,N+ andn+ (N–n+) for local shifts of the chemical potential _n in the dc limit is examined (n is the number of the relevant site calculated from a boundary of the chain). It is shown especially that the rate equation treatment (régime a) on the one hand and numerical or percolation treatments (régime c) on the other hand never yield the same bulk values of _r.     

On the determination of the position of the energy level of surface recombination centres

A detailed analysis of the dependence of the surface recombination velocitys on the surface potential _s leads to the conclusion that the position of the surface recombination level with respect to the centre of the energy gapE _t -E _i does not coincide with the valueq _s *, while the surface recombination velocitys decreases to half its maximum value. The difference between the two quantities is negligible only when the width of the curves( _s ) between the points corresponding to the valuess=1/2s _max is greater than 8kT.

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s _s , E _t -E _{i s} , s . , s( _s ) , s=1/2s _max, 8kT.

     

ФИЗИЧЕСКИЕ ОСНОВЫ ИЗ МЕРЕНИЯ НАПРАВЛЕНИЯ ВОЗДУШНОГО ПОТОКА МЕ ТОДОМ НАКАЛЕННОЙ ПРО ВОЛОКИ ПРИ ВЫСОКНХ ПОДЗВУКО ВЫХ СКОРОСТЯХ

d - l - t _d R _max - J , ( ) - - , . . - ( ) - - R R _max —R. ,      

Sufficient subalgebras and the relative entropy of states of a von Neumann algebra

A subalgebraM ₀ of a von Neumann algebraM is called weakly sufficient with respect to a pair (,) of states if the relative entropy of and coincides with the relative entropy of their restrictions toM ₀. The main result says thatM ₀ is weakly sufficient for (,) if and only ifM ₀ contains the Radon-Nikodym cocycle [D,D] _t . Other conditions are formulated in terms of generalized conditional expectations and the relative Hamiltonian.     

К ТЕОРИИ ГРАВИТАЦИОННОГО ИЗЛУЧЕНИЯ

. , , , . , . . . . , , . ; , .

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On the theory of gravitational radiation

The equations of motion of weakly radiating particles are investigated in a linear approximation in which the pseudo-Euclidian metric remains valid but energy changes caused by gravitational radiation are considered. The classical relativistic equations of motion with variable rest mass are applied. An elementary theory of the gravitational radiation of a rotator is formulated. The results are applied for particles in circular accelerators. It is found that a rotator with non-zero rest mass cannot exist for an unlimited period and that it cannot exceed the velocity of light. This explains why particles with non-zero rest mass cannot attain the velocity of light in circular accelerators; it is also shown that the gravitational radiation of particles in circular accelerators does not exist in practice.

     

Cyclotron instabilities of a two-component electron plasma

A study is made of instability at frequencies close to the electron cyclotron frequency _B and its multiples, subject to the presence of two different groups of electrons. It is shown that a mixture of hot and cold electrons ( _ph ² _pc ² ) in the region of frequencies s _B, s2 can be unstable with respect to waves of the flute type (k _z=0) with maximum increment _max ( _ph/_pc). _B, if there exists an interval of transversal velocities in whichF/ >0. When the curvature of the magnetic field is taken into account, even waves with _B can be unstable in such a plasma. The effect of spatial inhomogeneity of the hot component on flute-type instability and on two-beam cyclotron instability is also examined.The author extends his thanks to A. B. Mikhajlovskij for his valuable comments and discussions.     

О ВЛИЯНИИ ДИСЛОКАЦИЙ НА КОЭРЦИТИВНУЮ СИЛУ ФЕРРОМАГНЕТИКО В

- . ( + ) - , , - . , . , -, , , - , - . - . (- - ) . .     

Possible generalization of Boltzmann-Gibbs statistics

With the use of a quantity normally scaled in multifractals, a generalized form is postulated for entropy, namelyS _q k [1 – _i=1 ^W p _i ^q ]/(q-1), whereq characterizes the generalization andp _i are the probabilities associated withW (microscopic) configurations (W). The main properties associated with this entropy are established, particularly those corresponding to the microcanonical and canonical ensembles. The Boltzmann-Gibbs statistics is recovered as theq1 limit.