Evolution of a black hole-inhabited brane close to reconnection

Last moments of a mini black hole escaping from a brane are studied. It is argued that at the point of reconnection, where the piece of the brane attached to the black hole separates from the rest, the worldsheet of the brane becomes isotropic (light-like). The degenerate mode of evolution, with the worldsheet isotropic everywhere, is investigated. In particular, it is shown that the brane approaches the reconnection point from below if it reconnects within a certain limit distance, and from above if it reconnects beyond that distance. The rate of relaxation to the degenerate mode is established. If the dimension of the brane is $p$, the nondegeneracy, measured by the determinant of the relevant part of the induced metric tensor, falls down as (latitudinal angle)$^{2(p - 1)}$.Comment: 20 pages, 4 figure

On apparent breaking the second law of thermodynamics in quantum transport studies

We consider a model for stationary electronic transport through a one-dimensional chain of two leads attached to a perturbed central region (quantum dot) in the regime where the theory proposed recently by Capek for a similar model of phonon transport predicts the striking phenomenon of a permanent current between the leads. This result based on a rigorous but asymptotic Davies theory is at variance with the zero current yielded by direct transport calculations which can be carried out in the present model. We find the permanent current to be within the error of the asymptotic expansion for finite couplings, and identify cancelling terms of the same order.Comment: 5 pages, 3 figure

Multi-Particle Universal Processes

We generalize bipartite universal processes to the subclass of multi-particle universal processes from one to N particles. We show how the general statement for a multi-particle universal process can be constructed. The one-parameter family of processes generating totally anti-symmetric states has been generalized to a multi-particle regime and its entanglement properties have been studied. A view is given on the complete positivity and the possible physical realization of universal processes.

Simple models suffice for the single dot quantum shuttle

A quantum shuttle is an archetypical nanoelectromechanical device, where the mechanical degree of freedom is quantized. Using a full-scale numerical solution of the generalized master equation describing the shuttle, we have recently shown [Novotn\'{y} {\it et al.}, Phys. Rev. Lett. {\bf 92}, 248302 (2004)] that for certain limits of the shuttle parameters one can distinguish three distinct charge transport mechanisms: (i) an incoherent tunneling regime, (ii) a shuttling regime, where the charge transport is synchronous with the mechanical motion, and (iii) a coexistence regime, where the device switches between the tunneling and shuttling regimes. While a study of the cross-over between these three regimes requires the full numerics, we show here that by identifying the appropriate time-scales it is possible to derive vastly simpler equations for each of the three regimes. The simplified equations allow a clear physical interpretation, are easily solved, and are in good agreement with the full numerics in their respective domains of validity.Comment: 23 pages, 14 figures, invited paper for the Focus issue of the New Journal of Physics on Nano-electromechanical system

Territorial cohesion and structural funds programmes: urban development and territorial cooperation

Paper focusing on territorial cohesion and the structural funds programme in Europe

Defining rural areas of Visegrad countries

The article is focused on the introduction and categorization of various approaches to rurality, and the identification and delimitation of rural areas in Visegrad countries. Three substantively different groups of conceptualizations and definitions of rural and rurality are described as follows: functional definitions, rural as locality (political-economic approaches), and social representation. Latter, basic sorts of methods and appro - aches to the delimitation of rural areas in V4 countries are introduced emphasizing its historical development, differences in spatial level and criteria of delimitation in current research. Due to different nature of rural areas and even local administrative units (the basic units usually used for delimitation of rural areas), it is not possible to reach sufficient and reliable identification of rural areas for whole V4 area using any of criteria or definitions applied in the research at national levels. Therefore, the average population density of entire V4 area was used as a main criterion for distinguishing between urban and rural LAU 2 at the whole Visegrad area level. Such approach is also affected by generalization but it captures various conditions in each country relatively well and moreover, it is comparable with the OECD and European Union methods to some extent

Full counting statistics of nano-electromechanical systems

We develop a theory for the full counting statistics (FCS) for a class of nanoelectromechanical systems (NEMS), describable by a Markovian generalized master equation. The theory is applied to two specific examples of current interest: vibrating C60 molecules and quantum shuttles. We report a numerical evaluation of the first three cumulants for the C60-setup; for the quantum shuttle we use the third cumulant to substantiate that the giant enhancement in noise observed at the shuttling transition is due to a slow switching between two competing conduction channels. Especially the last example illustrates the power of the FCS.Comment: 7 pages, 3 figures; minor changes - final version as published in Europhys. Let

The influence of charge detection on counting statistics

We consider the counting statistics of electron transport through a double quantum dot with special emphasis on the dephasing induced by a nearby charge detector. The double dot is embedded in a dissipative enviroment, and the presence of electrons on the double dot is detected with a nearby quantum point contact. Charge transport through the double dot is governed by a non-Markovian generalized master equation. We describe how the cumulants of the current can be obtained for such problems, and investigate the difference between the dephasing mechanisms induced by the quantum point contact and the coupling to the external heat bath. Finally, we consider various open questions of relevance to future research.Comment: 15 pages, 2 figures, Contribution to 5-th International Conference on Unsolved Problems on Noise, Lyon, France, June 2-6, 200