3,699 research outputs found
Regulation of new markets in telecommunications? Market dynamics and shrinking monopolistic bottlenecks
This paper aims at localizing network-specific market power in new markets. Three kinds of transmission qualities on service markets can be differentiated according to the products provided: narrowband services like PSTN/ISDN or GSM, semi high-speed broadband services like broadband internet access up to 6 Mbps download and VDSL services up to 50 Mbps. As long as, due to the absence of alternative network infrastructures, a monopolistic bottleneck in local infrastructure networks exists the question arises what the remaining bottleneck components are for these different markets. In this paper the shrinking-bottleneck hypothesis will be demonstrated. --
Some taste substances are direct activators of G-proteins
Amphiphilic substances may stimulate cellular events through direct activation of G-proteins. The present experiments indicate that several amphiphilic sweeteners and the bitter tastant, quinine, activate transducin and Gi/Go-proteins. Concentrations of taste substances required to activate G-proteins in vitro correlated with those used to elicit taste. These data support the hypothesis that amphiphilic taste substances may elicit taste through direct activation of G-proteins
Exceptional Points in Atomic Spectra
We report the existence of exceptional points for the hydrogen atom in
crossed magnetic and electric fields in numerical calculations. The resonances
of the system are investigated and it is shown how exceptional points can be
found by exploiting characteristic properties of the degeneracies, which are
branch point singularities. A possibility for the observation of exceptional
points in an experiment with atoms is proposed.Comment: 4 pages, 4 figures, 1 table, to be published in Physical Review
Letter
Electronic interaction in tax administration
In this article ways electronic interaction of tax authorities and taxpayers are considered. Prospects of tax department are also considered
Transition state theory for wave packet dynamics. I. Thermal decay in metastable Schr\"odinger systems
We demonstrate the application of transition state theory to wave packet
dynamics in metastable Schr\"odinger systems which are approached by means of a
variational ansatz for the wave function and whose dynamics is described within
the framework of a time-dependent variational principle. The application of
classical transition state theory, which requires knowledge of a classical
Hamilton function, is made possible by mapping the variational parameters to
classical phase space coordinates and constructing an appropriate Hamiltonian
in action variables. This mapping, which is performed by a normal form
expansion of the equations of motion and an additional adaptation to the energy
functional, as well as the requirements to the variational ansatz are discussed
in detail. The applicability of the procedure is demonstrated for a cubic model
potential for which we calculate thermal decay rates of a frozen Gaussian wave
function. The decay rate obtained with a narrow trial wave function agrees
perfectly with the results using the classical normal form of the corresponding
point particle. The results with a broader trial wave function go even beyond
the classical approach, i.e., they agree with those using the quantum normal
form. The method presented here will be applied to Bose-Einstein condensates in
the following paper [A. Junginger, M. Dorwarth, J. Main, and G. Wunner,
submitted to J. Phys. A].Comment: 21 pages, 3 figures, submitted to J. Phys.
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