Ising model in a quasiperiodic transverse field,percolation, and contact processes in quasiperiodic environments

Quantum Ising models in a transverse field are related to continuous-time percolation processes whose oriented percolation versions are contact processes. We study such models in the presence of quasiperiodic disorder and prove localization in the ground state, no percolation, and extinction, respectively, for sufficiently large disorder.     

Bemerkung zum Mechanismus der Diazotierung. II

Ohne Zusammenfassung     

Non-Newtonian flow past a stretching plate

In this paper we have considered the study of boundary layer flow past a stretching plate in visco-elastic fluid (Walters' liquid B Model).The solution of boundary layer equation of motion past a stretching plate is obtained by using similarity parameter method. The influence of visco-elastic parameterk ₀ ^* on the flow velocity is investigated.

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Zusammenfassung Die Arbeit behandelt die Grenzschichtströmung um eine gespannte Platte in einer viskoelastischen Flüssigkeit (Walters Flüssigkeitsmodell B).Die Lösung der Grenzschicht-Bewegungsgleichung für eine gespannte Platte wird durch die Ähnlichkeits-Parametermethode erzielt. Der Einfluß des viskoelastischen Parametersk ₀ ^* auf die Strömungsgeschwindigkeit wird untersucht.

     

Überlegungen zum System Wasserstoffsuperoxyd,Ferroion, Ferriion

Zusammenfassung Überlegungen zum System Wasserstoffsuperoxyd, Ferroion, Ferriion führen zu dem Schluß, daß die Frage nach Mechanismus und Kinetik der in diesem System sich abspielenden Reaktionen keineswegs als gelöst betrachtet werden kann.     

Die Anwendung der luminescenzmikroskopischen Sediment-Analyse in der erd?lgeologischen Grundlagenforschung

Ohne Zusammenfassung     

Effect of Pr-Ca substitution on the transport and magnetic behavior of LaMnO3 perovskite

The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO₃ perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good example of these properties is (La_1−2x Pr _x Ca _x )MnO₃ (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T _c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for understanding the structural, transport and magnetic properties are discussed in detail.     

Supersymmetry and the Parisi-Sourlas dimensional reduction: A rigorous proof

Functional integrals that are formally related to the average correlation functions of a classical field theory in the presence of random external sources are given a rigorous meaning. Their dimensional reduction to the Schwinger functions of the corresponding quantum field theory in two fewer dimensions is proven. This is done by reexpressing those functional integrals as expectations of a supersymmetric field theory. The Parisi-Sourlas dimensional reduction of a supersymmetric field theory to a usual quantum field theory in two fewer dimensions is proven.Partially supported by the NSF under grant MCS-8301889Partially supported by FAPESP     

Investigation of Zr3Fe hydride phases

Detailed Mössbauer studies of a series of hydrogenated Zr₃Fe samples have demonstrated the existence of several hydride phases with hydrogen concentration up to Zr₃FeH₈. Despite the overall similarity of the spectra, assessment of their parameters has identified separate groupings, each linked with a particular phase. At low temperatures magnetic ordering is observed for Zr₃FeH_5.3 and Zr₃FeH_6.9.     

Die Bestimmung der chemischen Zusammensetzung von Brennstoffasche

Ohne Zusammenfassung