Non-rationality of some fibrations associated to Klein surfaces

We study the polynomial fibration induced by the equation of the Klein surfaces obtained as quotient of finite linear groups of automorphisms of the plane; this surfaces are of type A, D, E, corresponding to their singularities. The generic fibre of the polynomial fibration is a surface defined over the function field of the line. We proved that it is not rational in cases D, E, although it is obviously rational in the case A. The group of automorphisms of the Klein surfaces is also described, and is linear and of finite dimension in cases D, E; this result being obviously false in case A.Comment: 18 page

Strains Induced by Point Defects in Graphene on a Metal

Strains strongly affect the properties of low-dimensional materials, such as graphene. By combining in situ, in operando, reflection high energy electron diffraction experiments with first-principles calculations, we show that large strains, above 2%, are present in graphene during its growth by chemical vapor deposition on Ir(111) and when it is subjected to oxygen etching and ion bombardment. Our results unravel the microscopic relationship between point defects and strains in epitaxial graphene and suggest new avenues for graphene nanostructuring and engineering its properties through introduction of defects and intercalation of atoms and molecules between graphene and its metal substrate

Normal metal tunnel junction-based superconducting quantum interference proximity transistor: the N-SQUIPT

We report the fabrication and characterization of an alternative design for a superconducting quantum interference proximity transistor (SQUIPT) based on a normal metal (N) probe. The absence of direct Josephson coupling between the proximized metal nanowire and the N probe allows us to observe the full modulation of the wire density of states around zero voltage and current \textit{via} the application of an external magnetic field. This results into a drastic suppression of power dissipation which can be as low as a few $\sim 10^{-17}$ W. In this context the interferometer allows an improvement of up to four orders of magnitude with respect to earlier SQUIPT designs, and makes it ideal for extra-low power cryogenic applications. In addition, the N-SQUIPT has been recently predicted to be the enabling candidate for the implementation of coherent caloritronic devices based on proximity effect.Comment: 5 pages, 4 color figure

Vortex distribution in the Lowest Landau Level

We study the vortex distribution of the wave functions minimizing the Gross Pitaevskii energy for a fast rotating condensate in the Lowest Landau Level (LLL): we prove that the minimizer cannot have a finite number of zeroes thus the lattice is infinite, but not uniform. This uses the explicit expression of the projector onto the LLL. We also show that any slow varying envelope function can be approximated in the LLL by distorting the lattice. This is used in particular to approximate the inverted parabola and understand the role of ``invisible'' vortices: the distortion of the lattice is very small in the Thomas Fermi region but quite large outside, where the "invisible" vortices lie.Comment: 4 pages, 1 figur

Dynamique des systèmes agraires : l'exercice du développement

Cet ouvrage est le résultat de réunions organisées sur le thème de la dynamique des systèmes agraires. Un premier cycle de réunions avait eu lieu en 1983-1984. Constatant qu'au cours de ces dernières décennies toutes les sociétés paysannes et pastorales ont été l'objet d'opérations de développement, les organisateurs du séminaire ont pensé qu'il fallait faire appel - donner la parole - à ceux qui les ont initiées, financées, animées, évaluées..."aux développeurs". ils ont entrepris en partant de leurs expériences de nous expliquer les objectifs et les moyens, la dynamique et les dérives, les résultats et le bilan d'actions conçues pour le développement rural. Chaque séance a été laissée à l'initiative d'un "développeur". L'histoire du projet est retracée par les acteurs eux-mêmes. La narration se réfère aux expériences vécues, aux motivations, et à l'engagement personnels ; elle met en cause les institutions,elle nous plonge dans le milieu rural en jeu. Les intervenants ont su nous intéresser à leur savoir-faire, et au-delà, à toutes les actions conduites dans le "projet". Tous se sont situés à l'articulation de la pratique et de l'analyse ; mais ils ont soulignés la difficulté de construire et de respecter des logiques de recherche quand on est pris dans l'engrenage de l'action. Quand au point de vue critique, le temps et le recul ont fait leur oeuvre. Il restait à élargir le débat. En l'absence des principaux intéressés - les paysans, éleveurs...directement visés par le projet - des participants au séminaire connaissant les régions évoquées ou les problèmes soulevés ont nourri la confrontation. Ce sont notamment des chercheurs pour qui les opérations de développement sont objet de recherche et qui, d'ordinaire, en découvrent les bilans à posteriori, sans trop s'attarder sur les modalités pratiques de l'intervention. Ces textes - récits informés et critiques d'expériences de développement - nous disent l'ambition, l'ampleur et la difficulté de la tâche.(résumé d'auteur

Discontinuous Change in the Smectic Layer Thickness in Ferrielectric Liquid Crystals

The temperature dependence of the thickness of thick free-standing films is studied using a high-resolution film thickness measurement technique. A small discontinuity in the temperature dependence of the smectic layer thickness at every phase transition between ferro-, ferri-, and antiferroelectric phases is observed. We show that the major contribution to it arises from a change in the smectic tilt angle

Enhanced Recovery after Elective Colorectal Surgery - Reasons for Non-Compliance with the Protocol.

Enhanced recovery after surgery (ERAS) protocols for elective colorectal surgery reduce the intensity of postoperative complications, hospital stays and costs. Improvements in clinical outcome are directly proportional to the adherence to the recommended pathway (compliance). The aim of the present study was to analyze reasons for the non-compliance of colorectal surgeries with the ERAS protocol. A consecutive cohort of patients undergoing elective colorectal surgery was prospectively analyzed with regards to the surgery's compliance with the ERAS protocol. The reason for every single protocol deviation was documented and the decision was categorized based on whether it was medically justified or not. During the 8-month study period, 76 patients were included. The overall compliance with 22 ERAS items was 76% (96% in the preoperative, 82% in the perioperative, and 63% in the postoperative period). The decision to deviate from the clinical pathway was mainly a medical decision, while patients and nurses were responsible in 26 and 14% of the cases, respectively. However, reasons for non-compliance were medically justified in 78% of the study participants. 'Non-compliance' with the ERAS protocol was observed mostly in the postoperative period. Most deviations from the pathway were decided by doctors and in a majority of cases it appeared that they were due to a medical necessity rather than non-compliance. However, almost a quarter of deviations that were absolutely required are still amenable to improvement

Discrete-row growth of xenon adsorbed on the vicinal Pt(997) surface: Comparison between theory and experiment

Xe exhibits a discrete-row growth mode on the vicinal Pt(997) surface by sequential attachment to the substrate steps. In order to interpret experimental results obtained by grazing incidence helium scattering, potential calculations are performed. A mean-field Hamiltonian within the two-dimensional Ising model is shown to explain the sequential-row growth observed in helium-atom diffraction studies. More specifically, the calculated temperatures for the occurrence of each row depend mainly on the shape of the potential increment due to the steps and countersteps. They are in good agreement with the experimental values associated with maxima in the scattered He intensity versus coverage curves

Principales Factores de Virulencia de Periodontopatógenos Orales - Dentaid

La gingivitis y la periodontitis son enfermedades causadas en un inicio por un conjunto específico de bacterias orales. Aun así, ninguna de estas bacterias es capaz por sí sola de generar una enfermedad tan compleja como la periodontitis, sino que el proceso está orquestado por un selecto grupo de microorganismos con múltiples interacciones que promueven la respuesta inflamatoria, la destrucción tisular y la reabsorción ósea. Entre los periodontopatógenos más destacados se encuentran Aggregatibacter actinomycetemcomitans y Porphyromonas gingivalis