Thomas Young et la théorie ondulatoire de la lumière

Dans une série d’articles entre 1800 et 1803, Young explique un certain nombre de ses expériences, dont l’expérience dite des deux « fentes de Young ». Il introduit le terme d’interférences lumineuses – qui sera universellement repris. Tout en suivant le raisonnement sur celui de Newton dans Opticks (1704), en en citant plusieurs passages, Young s’écarte de la théorie corpusculaire de son compatriote, pour étayer la théorie ondulatoire de la lumière (initialement imaginée par Huygens). Il essaie aussi d’expliquer par la théorie ondulatoire la diffraction par une seule fente. L’ensemble de ses résultats seront repris par le physicien français Fresnel (sur l’instigation d’Arago), avec qui Young sera en correspondance suivie. Fresnel leur donnera une base mathématique et physique rigoureuse.In a series of articles written between 1800 and 1803, Young explains a number of his experiments, including the experiment known as “Young’s double-slit experiment”. He introduces the term light interferences, which would be universally accepted. Although Young adhered to Newton’s reasoning in Opticks (1704) and cited several passages from it, he diverged from his compatriot’s corpuscular theory of light and developed the wave theory of light (initially conceived by Huygens). He also strove to explain single-slit diffraction using wave theory. The sum of his results would be taken up by the French physicist Fresnel (at the instigation of Arago), with whom Young would regularly correspond. Fresnel would consolidate Young’s results by providing them with a rigorous mathematical and physical rationale

Terahertz multispectral imaging by thermo-conversion using MIM antenna

International audienceConversion of terahertz radiation into thermal radiation is a low-cost approach for terahertz detection by standard infrared camera. In this work, THz→IR thermo-conversion is performed by the combination of a THz absorber made of MIM antenna and an emissive layer made of carbon nanotubes. Structural and optical characterizations of the membrane are done, and multispectral imaging in the terahertz range is demonstrated

Semiconductor nanostructures for spectral filtering

International audienceWe present theoretical and experimental study of nanostructured guided-mode resonant filter, made of a highly doped InAsSb grating and a GaSb waveguide

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Robert Noel Hall

Ingénieur et physicien américain, monument de la physique du solide (au même titre que Bardeen ou Schockley) et néanmoins esprit discret et modeste, Robert Noel Hall a développé, pratiquement seul, le procédé de purification du germanium, découvert le concept de jonction PIN et mis au point le tout premier laser à semi-conducteur en 1962. Après une carrière menée tout entière à la General Electric (45 ans !), cet inventeur prolifique et fécond maintient aujourd’hui encore, à près de 90 ans, une activité soutenue de consultant en physique