Freiburg : Institut für ökumenische Studien der Universität Freiburg Schweiz, 2013
(Studia oecumenica Friburgensia ; 59)
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In: Scientific Reports, 2013, vol. 3, p. -
Zipf's law on word frequency and Heaps' law on the growth of distinct words are observed in Indo-European language family, but it does not hold for languages like Chinese, Japanese and Korean. These languages consist of characters, and are of very limited dictionary sizes. Extensive experiments show that: (i) The character frequency distribution follows a power law with exponent close to one, at...
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In: EPL (Europhysics Letters), 2013, vol. 101, no. 2, p. 20008
Recommender systems recommend objects regardless of potential adverse effects of their overcrowding. We address this shortcoming by introducing crowd-avoiding recommendation where each object can be shared by only a limited number of users or where object utility diminishes with the number of users sharing it. We use real data to show that contrary to expectations, the introduction of these...
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In: The European Physical Journal B, 2013, vol. 86, no. 2, p. 1-8
People in the Internet era have to cope with the information overload, striving to find what they are interested in, and usually face this situation by following a limited number of sources or friends that best match their interests. A recent line of research, namely adaptive social recommendation, has therefore emerged to optimize the information propagation in social networks and provide...
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In: Physica A: Statistical Mechanics and its Applications, 2013, p. -
In a recent work [T. Zhou, Z. Kuscsik, J.-G. Liu, M. Medo, J.R. Wakeling, Y.-C. Zhang, Proc. Natl. Acad. Sci. 107 (2010) 4511], a personalized recommendation algorithm with high performance in both accuracy and diversity is proposed. This method is based on the hybridization of two single algorithms called probability spreading and heat conduction, which respectively are inclined to recommend...
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In: EPL (Europhysics Letters), 2013, vol. 101, no. 4, p. 47007
We study the response of quantum many-body systems to coupling some of their degrees of freedom to external gauge fields. This serves to understand the current Green functions and transport properties of interacting many-body systems. Our analysis leads to a "gauge theory of states of matter" complementary to the well-known Landau theory of order parameters. We illustrate the power of our...
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In: Physical Review E, 2013, vol. 87, no. 2, p. 023305
We investigate the possibility to assist the numerically ill-posed calculation of spectral properties of interacting quantum systems in thermal equilibrium by extending the imaginary-time simulation to a finite Schwinger-Keldysh contour. The effect of this extension is tested within the standard maximum entropy approach to analytic continuation. We find that the inclusion of real-time data...
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In: Physical Review A, 2013, vol. 87, no. 2, p. 022513
We present an experimental study of laser-induced fluorescence spectra of Cs atoms embedded in superfluid and solid ⁴He, as well as in dense supercritical fluid He. The studied temperature range is increased with respect to earlier studies by the use of intense laser pulses for the transient local heating of the helium sample. The analysis of the experimental spectra is based on two different...
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In: Physical Review Letters, 2013, vol. 110, no. 5, p. 058303
We show that gels formed by arrested spinodal decomposition of protein solutions exhibit elastic properties in two distinct frequency domains, both elastic moduli exhibiting a remarkably strong dependence on volume fraction. Considering the large difference between the protein size and the characteristic length of the network we model the gels as porous media and show that the high and low...
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In: Zur Genealogied es politischen Raums; VS Verlag für sozialwissenschaften, 2006, p. 53-76
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