Trennung des Mono- Di- und Triaethylamins

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Limits to time variation of fundamental constants from comparisons of atomic frequency standards

Comparisons between frequency standards based on optical and microwave transitionsin atoms and ions currently provide the most stringent laboratory limitson present-day local variation of the fundamental constants.This paper discusses the sensitivity of these frequency standards to variation ofthe electromagnetic and strong interactions, summarises the constraints onvariation of these interactions which can be obtained from currently-available data, and discusses the magnitude of improvements in these limits which is anticipated fromexperiments currently underway.     

Reaction auf Blaus?ure

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Ueber die Einwirkung des Lichtes auf Chlor- und Bromsilber

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The Dixmier trace and asymptotics of zeta functions

We obtain general theorems which enable the calculation of the Dixmier trace in terms of the asymptotics of the zeta function and of the trace of the heat semigroup. We prove our results in a general semi-finite von Neumann algebra. We find for p>1 that the asymptotics of the zeta function determines an ideal strictly larger than Lp,∞ on which the Dixmier trace may be defined. We also establish stronger versions of other results on Dixmier traces and zeta functions.     

Ueber die L?slichkeit einiger Silbersalze in L?sungen von citronensaurem Natron

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Quantum Hall Effect on the Hyperbolic Plane in the Presence of Disorder

We study both the continuous model and the discrete model of the quantum Hall effect (QHE) on the hyperbolic plane in the presence of disorder, extending the results of an earlier paper. Here we model impurities, that is we consider the effect of a random or almost periodic potential as opposed to just periodic potentials. The Hall conductance is identified as a geometric invariant associated to an algebra of observables, which has plateaus at gaps in extended states of the Hamiltonian. We use the Fredholm modules defined in Comm. Math. Phys. 190 (1998), 629–673, to prove the integrality of the Hall conductance in this case. We also prove that there are always only a finite number of gaps in extended states of any random discrete Hamiltonian.     

Differential twisted K-theory and applications

In this paper, we develop differential twisted K-theory and define a twisted Chern character on twisted K-theory which depends on a choice of connection and curving on the twisting gerbe. We also establish the general Riemann–Roch theorem in twisted K-theory and find some applications in the study of twisted K-theory of compact simple Lie groups.