Classification of Non-Affine Non-Hecke Dynamical R-Matrices

A complete classification of non-affine dynamical quantum $R$-matrices obeying the ${\mathcal G}l_n({\mathbb C})$-Gervais-Neveu-Felder equation is obtained without assuming either Hecke or weak Hecke conditions. More general dynamical dependences are observed. It is shown that any solution is built upon elementary blocks, which individually satisfy the weak Hecke condition. Each solution is in particular characterized by an arbitrary partition ${{\mathbb I}(i), i\in{1,...,n}}$ of the set of indices ${1,...,n}$ into classes, ${\mathbb I}(i)$ being the class of the index $i$, and an arbitrary family of signs $(\epsilon_{\mathbb I})_{{\mathbb I}\in{{\mathbb I}(i), i\in{1,...,n}}}$ on this partition. The weak Hecke-type $R$-matrices exhibit the analytical behaviour $R_{ij,ji}=f(\epsilon_{{\mathbb I}(i)}\Lambda_{{\mathbb I}(i)}-\epsilon_{{\mathbb I}(j)}\Lambda_{{\mathbb I}(j)})$, where $f$ is a particular trigonometric or rational function, $\Lambda_{{\mathbb I}(i)}=\sum\limits_{j\in{\mathbb I}(i)}\lambda_j$, and $(\lambda_i)_{i\in{1,...,n}}$ denotes the family of dynamical coordinates

Gate-modulated thermopower in disordered nanowires: I. Low temperature coherent regime

Using a one-dimensional tight-binding Anderson model, we study a disordered nanowire in the presence of an external gate which can be used for depleting its carrier density (field effect transistor device configuration). In this first paper, we consider the low temperature coherent regime where the electron transmission through the nanowire remains elastic. In the limit where the nanowire length exceeds the electron localization length, we derive three analytical expressions for the typical value of the thermopower as a function of the gate potential, in the cases where the electron transport takes place (i) inside the impurity band of the nanowire, (ii) around its band edges and eventually (iii) outside its band. We obtain a very large enhancement of the typical thermopower at the band edges, while the sample to sample fluctuations around the typical value exhibit a sharp crossover from a Lorentzian distribution inside the impurity band towards a Gaussian distribution as the band edges are approached.Comment: 13 pages, 8 figures, final version as publishe

Scanning Gate Microscopy of Quantum Contacts Under Parallel Magnetic Field: Beating Patterns Between Spin-Split Transmission Peaks or Channel Openings

We study the conductance $g$ of an electron interferometer created in a two dimensional electron gas between a nanostructured contact and the depletion region induced by the charged tip of a scanning gate microscope. Using non-interacting models, we study the beating pattern of interference fringes exhibited by the images giving $g$ as a function of the tip position when a parallel magnetic field is applied. The analytical solution of a simplified model allows us to distinguish between two cases: (i) If the field is applied everywhere, the beating of Fabry-P\'erot oscillations of opposite spins gives rise to interference rings which can be observed at low temperatures when the contact is open between spin-split transmission resonances. (ii) If the field acts only upon the contact, the interference rings cannot be observed at low temperatures, but only at temperatures of the order of the Zeeman energy. For a contact made of two sites in series, a model often used for describing an inversion-symmetric double-dot setup, a pseudo-spin degeneracy is broken by the inter-dot coupling and a similar beating effect can be observed without magnetic field at temperatures of the order of the interdot coupling. Eventually, numerical studies of a quantum point contact with quantized conductance plateaus confirm that a parallel magnetic field applied everywhere or only upon the contact gives rises to similar beating effects between spin-split channel openings.Comment: 11 pages, 17 figure

Comparison of two extraction methods for ergosterol determination in vegetal feeds

Ergosterol is the principal sterol of fungi in which it plays an essential role in cell membrane and other cellular constituents. This sterol is considered as a good marker of fungal contamination and of mycotoxin production. After validation of ergosterol quantification by HPLC-UV system (linearity range: 0.2 to 20.0 mg/ml, repeatability: 3.27%, between day precision: 4.75%), 2 extraction methods of ergosterol from 3 vegetal matrixes (maize, barley and wheat) were compared: the first one, normalized by the AFNOR, is based on solid phase extraction (SPE), while the other is based on liquid/liquid extraction (LLE). The LLE procedure allowed ergosterol extraction gains of around 20% for high initial sterol contents (3 to 5 mg/kg) in naturally contaminated matrixes or in spiked samples, and of 86% for low initial sterol contents (1-2 mg/kg) in maize. Moreover, the precision of ergosterol determination was comparable for the 2 methods even if it was slightly lower using LLE and was more affected by the initial ergosterol contents in vegetal matrix than by its nature. These results suggest that ergosterol contents in vegetal feeds would be underestimated with the official method (SPE) and emphasize the importance of the extraction step

Absorbing/Emitting Phonons with one dimensional MOSFETs

We consider nanowires in the field effect transistor device configuration. Modeling each nanowire as a one dimensional lattice with random site potentials, we study the heat exchanges between the nanowire electrons and the substrate phonons, when electron transport is due to phonon-assisted hops between localized states. Shifting the nanowire conduction band with a metallic gate induces different behaviors. When the Fermi potential is located near the band center, a bias voltage gives rise to small local heat exchanges which fluctuate randomly along the nanowire. When it is located near one of the band edges, the bias voltage yields heat currents which flow mainly from the substrate towards the nanowire near one boundary of the nanowire, and in the opposite direction near the other boundary. This opens interesting perspectives for heat management at submicron scales: Arrays of parallel gated nanowires could be used for a field control of phonon emission/absorption.Comment: 9 pages, 11 figure

Les enjeux quotidiens avec lesquels doivent vivre les personnes schizophrènes désinstitutionnalisées de la région des Bois-Francs : le point de vue d'intervenants spécialisés

Affiche présentée dans le cadre du colloque de l'ARC "La gestion de la propriété intellectuelle : courants de pensée et facteurs de succès", lors du 81e Congrès de l'Acfas à l'Université Laval, le 8 mai 2013.Le deuxième prix ex aequo a été décerné à Geneviève Rivard au concours des Prix étudiants 2012-2013 de l'ARC.Dans le monde, une personne sur cent souffre de schizophrénie. Or ce trouble reste méconnu, malgré les souffrances qui y sont associées. Peu de chercheurs ont étudié les enjeux sociaux entourant la vie des schizophrènes. La présente recherche décrit ces enjeux selon le point de vue d'intervenants en santé mentale. Les résultats obtenus nous informent sur la vie quotidienne des schizophrènes et sur leurs relations avec leur entourage. Suit une discussion sur les relations interpersonnelles difficiles des personnes atteintes ainsi que les préjugés entretenus par la population

L’enquête criminelle

L’enquête de police judiciaire constitue, d’après une étude récente de Skogan et Frydl (2003), l’un des objets les moins étudiés dans le champ des études sur la police. Cet article énonce certains des résultats d’une étude effectuée dans 153 dossiers d’homicide montés de 1990 à 2001 par un grand corps policier québécois. Le texte est divisé en quatre parties : (1) on propose d’abord un rapide bilan des écrits sur l’enquête de police judiciaire ; (2) le projet de recherche est ensuite présenté en faisant état de quelques difficultés d’ordre méthodologique ; (3) une taxinomie des principaux types d’enquête de police judiciaire est dressée, qui révèle que les enquêtes recèlent une diversité jusqu’ici relativement inaperçue ; (4) finalement des résultats empiriques sont énoncés, en particulier en ce qui a trait au temps consacré par les enquêteurs pour résoudre les affaires, aux facteurs les plus opérants dans la résolution des affaires et au rôle de la police scientifique et de l’expertise.According to a 2003 survey conducted by Skogan and Frydl, criminal investigation is one of the least studied topics in police research. This article presents some of the findings of an examination of 153 homicide files opened between 1990 and 2001 by a large police force in Quebec. The paper is divided in four parts: (1) First, a brief survey of the writings on criminal investigations is conducted; (2) Our research project is then described and some of the methodological difficulties encountered are discussed; (3) A categorization of the main types of criminal investigation is developed, revealing an unsuspected diversity among investigations; (4) Finally, empirical findings are presented, focusing on the time needed to clear a homicide case, on the main determinants of the clearance process, and on the role of forensics and expertise in solving cases