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Palovics R.,Hungarian Academy of Sciences | Palovics R.,Budapest University of Technology and Economics | Daroczy B.,Hungarian Academy of Sciences | Daroczy B.,Budapest University of Technology and Economics | And 7 more authors.
European Physical Journal B | Year: 2015

We investigate the statistical properties of votes of customers for spots of France collected by the startup company Nomao. The frequencies of votes per spot and per customer are characterized by a power law distribution which remains stable on a time scale of a decade when the number of votes is varied by almost two orders of magnitude. Using the computer science methods we explore the spectrum and the eigenvalues of a matrix containing user ratings to geolocalized items. Eigenvalues nicely map to large towns and regions but show certain level of instability as we modify the interpretation of the underlying matrix. We evaluate imputation strategies that provide improved prediction performance by reaching geographically smooth eigenvectors. We point on possible links between distribution of votes and the phenomenon of self-organized criticality. © 2015, EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg. Source


Ermann L.,GIyA | Shepelyansky D.L.,French National Center for Scientific Research
European Physical Journal B | Year: 2015

Using the United Nations COMTRADE database [United Nations Commodity Trade Statistics Database, available at: http://comtrade.un.org/db/. Accessed November (2014)] we construct the Google matrix G of multiproduct world trade between the UN countries and analyze the properties of trade flows on this network for years 1962−2010. This construction, based on Markov chains, treats all countries on equal democratic grounds independently of their richness and at the same time it considers the contributions of trade products proportionally to their trade volume. We consider the trade with 61 products for up to 227 countries. The obtained results show that the trade contribution of products is asymmetric: some of them are export oriented while others are import oriented even if the ranking by their trade volume is symmetric in respect to export and import after averaging over all world countries. The construction of the Google matrix allows to investigate the sensitivity of trade balance in respect to price variations of products, e.g. petroleum and gas, taking into account the world connectivity of trade links. The trade balance based on PageRank and CheiRank probabilities highlights the leading role of China and other BRICS countries in the world trade in recent years. We also show that the eigenstates of G with large eigenvalues select specific trade communities. © 2015, EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg. Source


Gonzalez De Urreta E.J.,GIyA | Gonzalez De Urreta E.J.,CONICET | Scoccola N.N.,Favaloro University
AIP Conference Proceedings | Year: 2011

We report on the application of the 1=Nc expansion of QCD to the description of the properties of non-strange excited baryons belonging to the [70;1-]-plet. In particular, we present the results of an improved determination of the corresponding mixing angles obtained by performing a simultaneous fit of masses, strong decay widths and e.m. helicity amplitudes. We find θ1 = 0:40(8) and θ3 = 2:81(10). These values are compatible with those determined in previous non-global analyses but have smaller uncertainties. © 2011 American Institute of Physics. Source


Pagura V.,GIyA | Pagura V.,CONICET | Dumm D.G.,CONICET | Scoccola N.N.,GIyA | Scoccola N.N.,Favaloro University
AIP Conference Proceedings | Year: 2013

We study a nonlocal extension of the so-called Polyakov Nambu-Jona-Lasinio model at finite temperature and chemical potential, considering the impact of the presence of dynamical quarks on the scale parameter appearing in the Polyakov potential. Both real and imaginary chemical potentials are considered. The effect of varying the current quark mass is also investigated. © 2013 American Institute of Physics. Source


Allen P.G.,GIyA | Scoccola N.N.,GIyA | Scoccola N.N.,CONICET | Scoccola N.N.,Favaloro University
AIP Conference Proceedings | Year: 2013

We analyze the influence of an intense magnetic field on the chiral phase transition within the Nambu Jona Lasinio model at finite temperature and chemical potential. In particular, we study the position of the Critical End Point (CEP) as a function of the magnetic field. © 2013 American Institute of Physics. Source

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