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Université de Fribourg

Statistical mechanics of competitive resource allocation using agent-based models

Chakraborti, Anirban ; Challet, Damien ; Chatterjee, Arnab ; Marsili, Matteo ; Zhang, Yi-Cheng ; Chakrabarti, Bikas K.

In: Physics Reports, 2015, vol. 552, p. 1–25

Demand outstrips available resources in most situations, which gives rise to competition, interaction and learning. In this article, we review a broad spectrum of multi-agent models of competition (El Farol Bar problem, Minority Game, Kolkata Paise Restaurant problem, Stable marriage problem, Parking space problem and others) and the methods used to understand them analytically. We emphasize the...

Université de Fribourg

Origin of micropores In late jurassic (Oxfordian) micrites of the eastern Paris basin, France

Carpentier, Cédric ; Ferry, Serge ; Lécuyer, Christophe ; Strasser, André ; Géraud, Yves ; Trouiller, Alain

In: Journal of Sedimentary Research, 2015, vol. 85, no. 6, p. 660–682

Porous micritic facies, either primary chalks or resulting from secondary destructive micritization, can constitute important hydrocarbon or water reservoirs. Characterization of reservoir properties and the understanding of factors which controlled the distribution of porosity are of primary interest to evaluate the prospective reserves. Middle and late Oxfordian limestones of the eastern Paris...

Université de Fribourg

Speckle fluctuations resolve the interdistance between incoherent point sources in complex media

Carminati, R. ; Cwilich, G. ; Froufe-Pérez, Luis S. ; Sáenz, J. J.

In: Physical Review A, 2015, vol. 91, no. 2, p. 023807

We study the fluctuations of the light emitted by two identical incoherent point sources in a disordered environment. The intensity-intensity correlation function and the speckle contrast, obtained after proper temporal and configurational averaging, encode the relative distance between the two sources. This suggests the intriguing possibility that intensity measurements at only one point in...

Université de Fribourg

Static versus dynamic analysis of the influence of gravity on concentration non-equilibrium fluctuations

Croccolo, Fabrizio ; Bataller, Henri ; Scheffold, Frank

In: The European Physical Journal E, 2014, vol. 37, no. 11, p. 1–5

In a binary fluid mixture subject to gravity and a stabilizing concentration gradient, concentration non-equilibrium fluctuations are long-ranged. While the gradient leads to an enhancement of the respective equilibrium fluctuations, the effect of gravity is a damping of fluctuations larger than a “characteristic” size. This damping is visible both in the fluctuation power spectrum probed...

Université de Fribourg

Hard sphere-like glass transition in eye lens α-crystallin solutions

Foffi, Giuseppe ; Savin, Gabriela ; Bucciarelli, Saskia ; Dorsaz, Nicolas ; Thurston, George M. ; Stradner, Anna ; Schurtenberger, Peter

In: Proceedings of the National Academy of Sciences, 2014, vol. 111, no. 47, p. 16748–16753

We study the equilibrium liquid structure and dynamics of dilute and concentrated bovine eye lens α-crystallin solutions, using small-angle X-ray scattering, static and dynamic light scattering, viscometry, molecular dynamics simulations, and mode-coupling theory. We find that a polydisperse Percus–Yevick hard-sphere liquid-structure model accurately reproduces both static light scattering...

Université de Fribourg

Charactrisation of particle assemblies by 3D cross correlation light scattering and diffusing wave spectroscopy

Scheffold, Frank

In: SPIE Proceedings, 2014, vol. 9232: International Conference on Optical Particle Characterization (OPC 2014), p. 923203–923203–4

To characterize the structural and dynamic properties of soft materials and small particles, information on the relevant mesoscopic length scales is required. Such information is often obtained from traditional static and dynamic light scattering (SLS/DLS) experiments in the single scattering regime. In many dense systems, however, these powerful techniques frequently fail due to strong multiple...

Université de Fribourg

Light Transport and localization in two-dimensional correlated disorder

Conley, Gaurasundar M. ; Burresi, Matteo ; Pratesi, Filippo ; Vynck, Kevin ; Wiersma, Diederik S.

In: Physical Review Letters, 2014, vol. 112, no. 14, p. 143901

Structural correlations in disordered media are known to affect significantly the propagation of waves. In this Letter, we theoretically investigate the transport and localization of light in 2D photonic structures with short-range correlated disorder. The problem is tackled semianalytically using the Baus-Colot model for the structure factor of correlated media and a modified independent...

Université de Fribourg

Li/Mg systematics in scleractinian corals: Calibration of the thermometer

Montagna, Paolo ; McCulloch, Malcolm ; Douville, Eric ; Correa, Matthias López ; Trotter, Julie ; Rodolfo-Metalpa, Riccardo ; Dissard, Delphine ; Ferrier-Pagès, Christine ; Frank, Norbert ; Freiwald, André ; Goldstein, Steve ; Mazzoli, Claudio ; Reynaud, Stephanie ; Rüggeberg, Andres ; Russo, Simone ; Taviani, Marco

In: Geochimica et Cosmochimica Acta, 2014, vol. 132, p. 288–310

We show that the Li/Mg systematics of a large suite of aragonitic coral skeletons, representing a wide range of species inhabiting disparate environments, provides a robust proxy for ambient seawater temperature. The corals encompass both zooxanthellate and azooxanthellate species (Acropora sp., Porites sp., Cladocora caespitosa, Lophelia pertusa, Madrepora...

Université de Fribourg

Dynamic depolarized light scattering of small round plasmonic nanoparticles: When imperfection is only perfect

Balog, Sandor ; Rodriguez-Lorenzo, Laura ; Monnier, Christophe A. ; Michen, Benjamin ; Obiols-Rabasa, Marc ; Casal-Dujat, Lucia ; Rothen-Rutishauser, Barbara ; Petri-Fink, Alke ; Schurtenberger, Peter

In: The Journal of Physical Chemistry C, 2014, vol. 118, no. 31, p. 17968–17974

Although small round gold nanoparticles (Au NPs) possess only a small degree of shape anisotropy, they support localized surface plasmon resonances and exhibit intrinsic optical anisotropy. These inherent features promote depolarized light scattering, whose temporal fluctuations carry information about rotational Brownian dynamics, and thus can be used to describe the size distribution of...

Université de Fribourg

The theoretical account of the ligand field bonding regime and magnetic anisotropy in the DySc₂N@C₈₀ single ion magnet endohedral fullerene

Cimpoesu, Fanica ; Dragoe, Nita ; Ramanantoanina, Harry ; Urland, Werner ; Daul, Claude

In: Physical Chemistry Chemical Physics, 2014, vol. 16, no. 23, p. 11337–11348

Considering the DySc₂N@C₈₀ system as a prototype for Single Ion Magnets (SIMs) based on endohedral fullerenes, we present methodological advances and state-of-the art computations analysing the electronic structure and its relationship with the magnetic properties due to the Dy(III) ion. The results of the quantum chemical calculations are quantitatively decrypted in the framework of ligand...