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Université de Fribourg

Hume on the Imagination

Dorsch, Fabian

In: The Routledge Handbook of Philosophy of Imagination

This chapter overviews Hume’s thoughts on the nature and the role of imagining, with an almost exclusive focus on the first book of his Treatise of Human Nature. Over the course of this text, Hume draws and discusses three important distinctions among our conscious mental episodes (or what he calls ‘perceptions’): (i) between impressions (including perceptual experiences) and ideas...

Université de Fribourg

Transcriptional control of neural crest specification into peripheral glia

Jacob, Claire

In: Glia, 2015, p. –

The neural crest is a transient migratory multipotent cell population that originates from the neural plate border and is formed at the end of gastrulation and during neurulation in vertebrate embryos. These cells give rise to many different cell types of the body such as chondrocytes, smooth muscle cells, endocrine cells, melanocytes, and cells of the peripheral nervous system including...

Université de Fribourg

Comparing impacts of alien plants and animals in Europe using a standard scoring system

Kumschick, Sabrina ; Bacher, Sven ; Evans, Thomas ; Marková, Zuzana ; Pergl, Jan ; Pyšek, Petr ; Vaes-Petignat, Sibylle ; Veer, Gabriel van der ; Vilà, Montserrat ; Nentwig, Wolfgang

In: Journal of Applied Ecology, 2015, vol. 52, no. 3, p. 552–561

Alien species can change the recipient environment in various ways, and some of them cause considerable damage. Understanding such impacts is crucial to direct management actions. This study addresses the following questions: Is it possible to quantify impact across higher taxa in a comparative manner? Do impacts differ between taxonomic groups? How are environmental and socio-economic impacts...

Université de Fribourg

Wolfe’s theorem for weakly differentiable cochains

Petit, Camille ; Rajala, Kai ; Wenger, Stefan

In: Journal of Functional Analysis, 2015, vol. 268, no. 8, p. 2261–2297

A fundamental theorem of Wolfe isometrically identifies the space of flat differential forms of dimension m in RⁿRn with the space of flat m-cochains, that is, the dual space of flat chains of dimension m in RⁿRn. The main purpose of the present paper is to generalize Wolfe's theorem to the setting of Sobolev differential forms and Sobolev cochains in RⁿRn....

Université de Fribourg

Superconductivity in the two-band Hubbard model

Koga, Akihisa ; Werner, Philipp

In: Physical Review B, 2015, vol. 91, no. 8, p. 085108

We study the two-band Hubbard model in infinite dimensions by solving the dynamical mean-field equations with a strong coupling continuous-time quantum Monte Carlo method and show that an s-wave superconducting state can be stabilized in the repulsively interacting case. We discuss how this superconducting state competes with the metallic and paired Mott states. The effects of the Hund coupling...

Université de Fribourg

Nonequilibrium dynamical mean-field theory for bosonic lattice models

Strand, Hugo U. R. ; Eckstein, Martin ; Werner, Philipp

In: Physical Review X, 2015, vol. 5, no. 1, p. 011038

We develop the nonequilibrium extension of bosonic dynamical mean-field theory and a Nambu real-time strong-coupling perturbative impurity solver. In contrast to Gutzwiller mean-field theory and strong-coupling perturbative approaches, nonequilibrium bosonic dynamical mean-field theory captures not only dynamical transitions but also damping and thermalization effects at finite temperature. We...

Université de Fribourg

Field-induced polaron formation in the Holstein-Hubbard model

Werner, Philipp ; Eckstein, Martin

In: EPL (Europhysics Letters), 2015, vol. 109, no. 3, p. 37002

We study the effect of strong DC and pulsed electric fields on a Mott insulating system with coupling to optical phonons. A DC field of the order of the gap induces a metallic state characterized by polaronic features in the gap region and a partially inverted population. In this quasi-steady state, the field-induced doublon-hole production is balanced by a phonon-enhanced doublon-hole...

Université de Fribourg

Dynamical screening in ${\text{La}}_{2}{\text{CuO}}_{4}$

Werner, Philipp ; Sakuma, Rei ; Nilsson, Fredrik ; Aryasetiawan, Ferdi

In: Physical Review B, 2015, vol. 91, no. 12, p. 125142

We show that the dynamical screening of the Coulomb interaction among Cu-d electrons in high-Tc cuprates is strong and that a proper treatment of this effect is essential for a consistent description of the electronic structure. In particular, we find that ab initio calculations for undoped La2CuO4 in the paramagnetic phase yield an insulator only if the frequency dependence of the Coulomb...

Université de Fribourg

Competition between Energy-Dependent U and Nonlocal Self-Energy in Correlated Materials: Application of GW+DMFT to SrVO3

Sakuma, R. ; Werner, Philipp ; Aryasetiawan, F.

In: Proceedings of Computational Science Workshop 2014 (CSW2014), 2015, vol. 5, p. -

We describe an implementation of the GW+DMFT method and apply it to calculate the electronic structure of SrVO₃. Our results show that there is a strong competition between the frequency-dependent Hubbard U and the non-local self-energy via the GW approximation. It is crucial to take into account these two aspects in order to obtain an accurate and coherent picture of the...

Université de Fribourg

A sensitive and accurate atomic magnetometer based on free spin precession

Grujić, Zoran D. ; Koss, Peter A. ; Bison, Georg ; Weis, Antoine

In: The European Physical Journal D, 2015, vol. 69, no. 5, p. 1–10

We present a laser-based atomic magnetometer that allows inferring the modulus of a magnetic field from the free Larmor precession of spin-oriented Cs vapour atoms. The detection of free spin precession (FSP) is not subject to systematic readout errors that occur in phase feedback-controlled magnetometers in which the spin precession is actively driven by an oscillating field or a modulation of...