Dermatologie du sensible au xixe siècle

L’iconographie dermatologique du xixe siècle n’a pas seulement une visée purement cognitive d’enseignement, elle concerne également le domaine de la sensation et de la perception esthésiques. En effet, outre le fait d’illustrer la pensée médicale de l’époque, les dessins et les photographies révèlent les intentions de leurs auteurs ou de leurs commanditaires. Il s’agit ainsi, à travers cette analyse, de considérer l’iconographie dermatologique du xixe siècle selon les catégorisations du sensible et de l’intelligible et sous l’angle d’une sémiotique des cultures.The dermatological iconography of the xixe century does not have a purely cognitive or educational aim, it also relates to the senses and to “ perception esthesics ”. These drawings and photographs, not only do they illustrate the medical thought of their times, but they reveal the intentions of their authors or their sponsors. Our aim is to study, in this essay, the dermatological iconography of the xixe century, from the point of view of the senses, from a cognitive and intellective standpoint, as well as from the perspective of a semiotics of cultures

Partial charge transfer and absence of induced magnetization in EuS(111)/Bi2Se3 heterostructures

Heterostructures made from topological and magnetic insulators promise to form excellent platforms for new electronic and spintronic functionalities mediated by interfacial effects. We report the results of a first-principles density functional theory study of the geometric, electronic structure, and magnetic properties of the EuS(111)/Bi2Se3 interface, including van der Waals and relativistic spin-orbit effects. In contrast to previous theoretical studies, we find no appreciable magnetic anisotropy in such a heterostructure. We also do not see additional induced magnetization at the interface or the magnetic proximity effect on the topological states. This is due to the localized nature of Eu moments and because of a partial charge transfer of ∼0.5 electron from Eu to Se. The formation of the surface dipole shifts the Dirac cone about 0.4 eV below the chemical potential, and the associated electrostatic screening moves the topological state from the first to the second quintuple layer of Bi2Se3

The Threat to Weather Radars by Wireless Technology

Wireless technology, such as local area telecommunication networks and surveillance cameras, causes severe interference for weather radars because they use the same operational radio frequencies. One or two disturbances can be removed from the radar image, but the number and power of the interfering wireless devices are growing all over the world, threatening that one day the radars could become useless for weather observations. Some agencies have already changed or are considering changing frequency bands, but now even other bands are under threat. Use of equipment at radio frequencies is regulated by laws and international agreements. Technologies have been developed for peaceful coexistence. If wireless devices use these technologies to protect weather radars, their data transmission capabilities become limited, so it is tempting to violate the regulations. Hence, it is an important task for the worldwide weather community to involve themselves in the radio frequency management process and work in close contact with their national radio authorities to ensure that meteorological interests be duly taken into account in any decision-making process toward the future usage of wireless devices.United States. Federal Aviation Administration (FA8721-05-C-0002

Démontrer la capacité de l’agriculture à relever le défi énergétique: L’agriculture face à de multiples défis

première partie du dossier : Économies d’énergie et précarité énergétiqueabsen

An unexpected organometallic intermediate in surface-confined Ullmann coupling

Ullmann coupling or, more generally, dehalogenative aryl-aryl coupling, is one of the most widely exploited chemical reactions to obtain one- and two-dimensional polymers on metal surfaces. It is generally described as a two-step reaction: (i) dehalogenation, resulting in the formation of a stable intermediate organometallic phase and subsequent (ii) C-C coupling. The topology of the resulting polymer depends on the number and positions of the halogen atoms in the haloaromatic precursor, although its orientation and order are determined by the structure of the intermediate phase. Hitherto, only one intermediate structure, identified as an organometallic (OM) phase, has been reported for such a reaction. Here we demonstrate the formation of two distinct OM phases during the temperature-induced growth of poly(para-phenylene) from 1,4-dibromobenzene precursors on Cu(110). Beyond the already known linear-OM chains, we show that a phase reorganization to a chessboard-like 2D-OM can be activated in a well-defined temperature range. This new intermediate phase, revealed only when the reaction is carried out at low molecular coverages, was characterized by X-ray photoelectron spectroscopy, scanning tunneling microscopy and near-edge X-ray absorption fine structure spectroscopy, and modeled by density functional theory calculations. Our data show that the 2D-OM remains stable after cooling down the sample and is stabilized by four-Cu clusters at each node. The observation of such unexpected intermediate phase shows the complexity of the mechanisms underlying on-surface synthesis and broadens the understanding of Ullmann coupling, which continues to be astonishing despite its extensive use