Laughlin's topological charge pump in an atomic Hall cylinder

The quantum Hall effect occuring in two-dimensional electron gases was first explained by Laughlin, who envisioned a thought experiment that laid the groundwork for our understanding of topological quantum matter. His proposal is based on a quantum Hall cylinder periodically driven by an axial magnetic field, resulting in the quantized motion of electrons. We realize this milestone experiment with an ultracold gas of dysprosium atoms, the cyclic dimension being encoded in the electronic spin and the axial field controlled by the phases of laser-induced spin-orbit couplings. Our experiment provides a straightforward manifestation of the non-trivial topology of quantum Hall insulators, and could be generalized to strongly-correlated topological systems.Comment: 10 pages, 10 figure

Microstructure and electrical properties of (Ba0.6Sr0.4)0.85Bi0.1TiO3 ceramics prepared by single-step, liquid-phase, solid-state reactive sintering

(Ba0.6Sr0.4)0.85Bi0.1TiO3 ceramics have been obtained by single-step, liquid-phase, solid-state reactive sintering in the temperature range 1250–1350 °C using stoichiometric amounts of BaTiO3, SrTiO3 and Bi4Ti3O12. Their microstructure and electrical properties have been studied by X-Ray diffraction and fluorescence, scanning and transmission electron microscopy and impedance spectroscopy. The relative density, Dr, relative permittivity, ε′r, and dissipation factor, tan δ, at room temperature and the bulk and grain boundary resistivity, Rb and Rgb, and activation energies, Eba and Egba, are approximately independent of the sintering temperature with values around e.g. Dr ~97.5 %, ε′r ~1790, tan δ ~0.06 %, R500oCb ~26 kΩ cm, Egba ~1.03 eV, R500oCgb ~217 kΩ cm and Egba ~1.41 eV. By contrast, the temperature coefficient of capacitance, TCC, increases linearly from ~10 ppm oC−1 to ~21 ppm oC−1 on increasing sintering temperature. Comments on the influence of the sintering temperature on the chemical composition of the ceramics are made

Hierarchical Pressure In The Cockpit: An ERP Study

Many accident reports have stressed the fact that first officers sometimes follow risky choices made by captains, resulting in the mitigation of flight safety. While this tendency is well known in the field of aviation, few studies have examined the impact of captains’ influence on first officers’ decision-making and the associated neural correlates. The present study aimed to investigate the extent to which first officers are influenced by captains when the latter adopt a risky behavior. Student pilots who were about to complete their training participated in this study. In the first part of the experiment, they were presented with 50 different landing situations (i.e., pictures of Primary Flight Display, PFD)

Laser-Induced Electron Diffraction in Chiral Molecules

Strong laser pulses enable probing molecules with their own electrons. The oscillating electric field tears electrons off a molecule, accelerates them, and drives them back toward their parent ion within a few femtoseconds. The electrons are then diffracted by the molecular potential, encoding its structure and dynamics with angstrom and attosecond resolutions. Using elliptically polarized laser pulses, we show that laser-induced electron diffraction is sensitive to the chirality of the target. The field selectively ionizes molecules of a given orientation and drives the electrons along different sets of trajectories, leading them to recollide from different directions. Depending on the handedness of the molecule, the electrons are preferentially diffracted forward or backward along the light propagation axis. This asymmetry, reaching several percent, can be reversed for electrons recolliding from two ends of the molecule. The chiral sensitivity of laser-induced electron diffraction opens a new path to resolve ultrafast chiral dynamics

Tours et détours en bibliothèque. Carnet de voyage

Une bibliothèque pour faire quoi ? 19 écrivains et 1 plasticienne répondent, à leur manière – pour faire un tour, pour regarder un film, pour donner RDV, pour se mettre au chaud, pour lire, pour mettre le feu, pour parler de Flaubert, pour photographier le chantier, pour faire le ménage, pour être seul avec d'autres, pour travailler, pour dormir... Dans des styles différents, entre récits, nouvelles ou témoignages, les auteurs ont composé un portrait à multiples facettes de ce lieu public, et de ses passagers. Leurs textes reflètent aussi les grandes tendances de la littérature contemporaine, tournés pour certains vers le politique ou le social, pour d'autres vers le poétique ou le biographique. De son côté, en photographe, Aurélie Pétrel donne un ancrage visuel à ce Carnet de voyage

Non-Invasive Molecular Imaging of Fibrosis Using a Collagen-Targeted Peptidomimetic of the Platelet Collagen Receptor Glycoprotein VI

Background: Fibrosis, which is characterized by the pathological accumulation of collagen, is recognized as an important feature of many chronic diseases, and as such, constitutes an enormous health burden. We need non-invasive specific methods for the early diagnosis and follow-up of fibrosis in various disorders. Collagen targeting molecules are therefore of interest for potential in vivo imaging of fibrosis. In this study, we developed a collagen-specific probe using a new approach that takes advantage of the inherent specificity of Glycoprotein VI (GPVI), the main platelet receptor for collagens I and III. Methodology/Principal: Findings An anti-GPVI antibody that neutralizes collagen-binding was used to screen a bacterial random peptide library. A cyclic motif was identified, and the corresponding peptide (designated collagelin) was synthesized. Solid-phase binding assays and histochemical analysis showed that collagelin specifically bound to collagen (Kd 10−7 M) in vitro, and labelled collagen fibers ex vivo on sections of rat aorta and rat tail. Collagelin is therefore a new specific probe for collagen. The suitability of collagelin as an in vivo probe was tested in a rat model of healed myocardial infarctions (MI). Injecting Tc-99m-labelled collagelin and scintigraphic imaging showed that uptake of the probe occurred in the cardiac area of rats with MI, but not in controls. Post mortem autoradiography and histological analysis of heart sections showed that the labeled areas coincided with fibrosis. Scintigraphic molecular imaging with collagelin provides high resolution, and good contrast between the fibrotic scars and healthy tissues. The capacity of collagelin to image fibrosis in vivo was confirmed in a mouse model of lung fibrosis. Conclusion/Significance: Collagelin is a new collagen-targeting agent which may be useful for non-invasive detection of fibrosis in a broad spectrum of diseases.Psycholog

Tours et détours en bibliothèque. Carnet de voyage

Une bibliothèque pour faire quoi ? 19 écrivains et 1 plasticienne répondent, à leur manière – pour faire un tour, pour regarder un film, pour donner RDV, pour se mettre au chaud, pour lire, pour mettre le feu, pour parler de Flaubert, pour photographier le chantier, pour faire le ménage, pour être seul avec d\u27autres, pour travailler, pour dormir... Dans des styles différents, entre récits, nouvelles ou témoignages, les auteurs ont composé un portrait à multiples facettes de ce lieu public, et de ses passagers. Leurs textes reflètent aussi les grandes tendances de la littérature contemporaine, tournés pour certains vers le politique ou le social, pour d\u27autres vers le poétique ou le biographique. De son côté, en photographe, Aurélie Pétrel donne un ancrage visuel à ce Carnet de voyage

The SuperCam Instrument Suite on the Mars 2020 Rover: Science Objectives and Mast-Unit Description

On the NASA 2020 rover mission to Jezero crater, the remote determination of the texture, mineralogy and chemistry of rocks is essential to quickly and thoroughly characterize an area and to optimize the selection of samples for return to Earth. As part of the Perseverance payload, SuperCam is a suite of five techniques that provide critical and complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), visible and near-infrared spectroscopy (VISIR), high-resolution color imaging (RMI), and acoustic recording (MIC). SuperCam operates at remote distances, primarily 2-7 m, while providing data at sub-mm to mm scales. We report on SuperCam's science objectives in the context of the Mars 2020 mission goals and ways the different techniques can address these questions. The instrument is made up of three separate subsystems: the Mast Unit is designed and built in France; the Body Unit is provided by the United States; the calibration target holder is contributed by Spain, and the targets themselves by the entire science team. This publication focuses on the design, development, and tests of the Mast Unit; companion papers describe the other units. The goal of this work is to provide an understanding of the technical choices made, the constraints that were imposed, and ultimately the validated performance of the flight model as it leaves Earth, and it will serve as the foundation for Mars operations and future processing of the data.In France was provided by the Centre National d'Etudes Spatiales (CNES). Human resources were provided in part by the Centre National de la Recherche Scientifique (CNRS) and universities. Funding was provided in the US by NASA's Mars Exploration Program. Some funding of data analyses at Los Alamos National Laboratory (LANL) was provided by laboratory-directed research and development funds

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men