88 research outputs found
Quantum compacton vacuum
We study the properties of classical and quantum compacton chains by means of
extensive numerical simulations. Such chains are strongly nonlinear and their
classical dynamics remains chaotic at arbitrarily low energies. We show that
the collective excitations of classical chains are described by sound waves
which decay rate scales algebraically with the wave number with a generic
exponent value. The properties of the quantum chains are studied by the quantum
Monte Carlo method and it is found that the low energy excitations are well
described by effective phonon modes with the sound velocity dependent on an
effective Planck constant. Our results show that at low energies the quantum
effects lead to a suppression of chaos and drive the system to a
quasi-integrable regime of effective phonon modes.Comment: RevTex 7 pages, 8 figs, research at http://www.quantware.ups-tlse.fr
Two-dimensional ranking of Wikipedia articles
The Library of Babel, described by Jorge Luis Borges, stores an enormous
amount of information. The Library exists {\it ab aeterno}. Wikipedia, a free
online encyclopaedia, becomes a modern analogue of such a Library. Information
retrieval and ranking of Wikipedia articles become the challenge of modern
society. While PageRank highlights very well known nodes with many ingoing
links, CheiRank highlights very communicative nodes with many outgoing links.
In this way the ranking becomes two-dimensional. Using CheiRank and PageRank we
analyze the properties of two-dimensional ranking of all Wikipedia English
articles and show that it gives their reliable classification with rich and
nontrivial features. Detailed studies are done for countries, universities,
personalities, physicists, chess players, Dow-Jones companies and other
categories.Comment: RevTex 9 pages, data, discussion added, more data at
http://www.quantware.ups-tlse.fr/QWLIB/2drankwikipedia
Quantum correlations and synchronization measures
The phenomenon of spontaneous synchronization is universal and only recently
advances have been made in the quantum domain. Being synchronization a kind of
temporal correlation among systems, it is interesting to understand its
connection with other measures of quantum correlations. We review here what is
known in the field, putting emphasis on measures and indicators of
synchronization which have been proposed in the literature, and comparing their
validity for different dynamical systems, highlighting when they give similar
insights and when they seem to fail.Comment: book chapter, 18 pages, 7 figures, Fanchini F., Soares Pinto D.,
Adesso G. (eds) Lectures on General Quantum Correlations and their
Applications. Quantum Science and Technology. Springer (2017
Google matrix of business process management
Development of efficient business process models and determination of their
characteristic properties are subject of intense interdisciplinary research.
Here, we consider a business process model as a directed graph. Its nodes
correspond to the units identified by the modeler and the link direction
indicates the causal dependencies between units. It is of primary interest to
obtain the stationary flow on such a directed graph, which corresponds to the
steady-state of a firm during the business process. Following the ideas
developed recently for the World Wide Web, we construct the Google matrix for
our business process model and analyze its spectral properties. The importance
of nodes is characterized by Page-Rank and recently proposed CheiRank and
2DRank, respectively. The results show that this two-dimensional ranking gives
a significant information about the influence and communication properties of
business model units. We argue that the Google matrix method, described here,
provides a new efficient tool helping companies to make their decisions on how
to evolve in the exceedingly dynamic global market.Comment: submitted to European Journal of Physics
How Well a Chaotic Quantum System Can Retain Memory of Its Initial State?
In classical mechanics the local exponential instability effaces the memory
of initial conditions and leads to practical irreversibility. In striking
contrast, quantum mechanics appears to exhibit strong memory of the initial
state. We relate the latter fact to the low (at most linear) rate with which
the system's Wigner function gets during evolution more and more complicated
structure and establish existence of a critical strength of external influence
below which such a memory still survives.Comment: 5 pages, 4 figure
Life trajectories of parents who’s parental rights were terminated: the sociological research
Life trajectories of parents who’s parental rights were terminated: the sociological research / O. A. Volkova [et al.] // Indo American journal of pharmaceutical sciences. - 2017. - N04(09).-P. 3128-3133. - Refer.: p. 3132-3133.The article presents the results of a sociological research conducted in 2016 in the Belgorod, Saratov regions and the Trans-Baikal Territory and includes two stages. On the first stage there was the expert survey (n=25), where the informants were employees of the guardianship authorities; social services; education, health care and law institution
Quantum phase transition in the Frenkel-Kontorova chain: from pinned instanton glass to sliding phonon gas
We study analytically and numerically the one-dimensional quantum
Frenkel-Kontorova chain in the regime when the classical model is located in
the pinned phase characterized by the gaped phonon excitations and devil's
staircase. By extensive quantum Monte Carlo simulations we show that for the
effective Planck constant smaller than the critical value the
quantum chain is in the pinned instanton glass phase. In this phase the
elementary excitations have two branches: phonons, separated from zero energy
by a finite gap, and instantons which have an exponentially small excitation
energy. At the quantum phase transition takes place and for
the pinned instanton glass is transformed into the sliding
phonon gas with gapless phonon excitations. This transition is accompanied by
the divergence of the spatial correlation length and appearence of sliding
modes at .Comment: revtex 16 pages, 18 figure
Fractal Spin Glass Properties of Low Energy Configurations in the Frenkel-Kontorova chain
We study numerically and analytically the classical one-dimensional
Frenkel-Kontorova chain in the regime of pinned phase characterized by phonon
gap. Our results show the existence of exponentially many static equilibrium
configurations which are exponentially close to the energy of the ground state.
The energies of these configurations form a fractal quasi-degenerate band
structure which is described on the basis of elementary excitations. Contrary
to the ground state, the configurations inside these bands are disordered.Comment: revtex, 9 pages, 9 figure
Karyotypical characteristics of two allopatric African populations of anhydrobiotic Polypedilum Kieffer, 1912 (Diptera, Chironomidae) originating from Nigeria and Malawi
© Ninel A. Petrova et al. The African chironomid Polypedilum vanderplanki Hinton, 1951 is the only chironomid able to withstand almost complete desiccation in an ametabolic state known as anhydrobiosis. The karyotypes of two allopatric populations of this anhydrobiotic chironomid, one from Nigeria and another from Malawi, were described according to the polytene giant chromosomes. The karyotype from the Nigerian population was presented as the reference chromosome map for P. vanderplanki. Both populations, Nigerian and Malawian, showed the same number of chromosomes (2n=8), but important differences were found in the band sequences of polytene chromosomes, and in the number and the arrangement of active regions between the two populations. Such important differences raise the possibility that the Malawian population could constitute a distinct new species of anhydrobiotic chironomid
Wigner crystal in snaked nanochannels
We study properties of Wigner crystal in snaked nanochannels and show that
they are characterized by conducting sliding phase at low charge densities and
insulating pinned phase emerging above a certain critical charge density. The
transition between these phases has a devil's staircase structure typical for
the Aubry transition in dynamical maps and the Frenkel-Kontorova model. We
discuss implications of this phenomenon for charge density waves in
quasi-one-dimensional organic conductors and for supercapacitors in nanopore
materials.Comment: 4 pages, 6 figs, research at http://www.quantware.ups-tlse.f
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