Taming Friedrich-Wintgen interference in resonant metasurface: vortex laser emitting at on-demand tilted-angle

Friedrich-Wintgen (FW) interference is an atypical coupling mechanism that grants loss exchange between leaky resonances in non-Hermitian classical and quantum systems. Intriguingly, such an mechanism makes it possible for destructive interference scenario in which a radiating wave becomes a bound state in the continuum (BIC) by giving away all of its losses. Here we propose and demonstrate experimentally an original concept to tailor FW-BICs as polarization singularity at on-demand wavevectors in optical metasurface. As a proof-of-concept, using hybrid organic-inorganic halide perovskite as active material, we empower this novel polarization singularity to obtain lasing emission exhibiting both highly directional emission at oblique angles and polarization vortex in momentum space. Our results pave the way to steerable coherent emission with tailored polarization pattern for applications in optical communication/manipulation in free-space, high-resolution imaging /focusing and data storage

Assessing walking posture with geometric morphometrics: Effects of rearing environment in pigs

International audienceRearing social animals like pigs in isolation from conspecifics can have consequences on behaviour and physiology. The aim of this experiment was to determine whether rearing conditions affect body postures. We adapted a method for quantitative evaluation of postures based on geometric morphometrics, developed in horses, for pigs and applied it in different conditions. Forty eight 75-day old females were reared either alone in 2.25 m2 pens (IH, N = 24 animals and 4 groups) or in groups of four in 4.64 m2 pens (GH, N = 24) for two weeks. They were habituated to human handling (stroking, speaking) and marking on their backs every day, and tested individually once a day for 10 min in a corridor outside the home pen during the two subsequent weeks. We observed their behaviour and posture during the first exposure to the test (novelty), and the fourth and fifth (after habituation). On the sixth and seventh tests, a familiar stockperson was present in the corridor (human presence). Before each test, the animals were marked with seven landmarks along their length, corresponding to anatomical points and easily located. An experimenter took pictures of the animals walking along the corridor, and these pictures were transferred to tps software for analysis. GH animals were more often active in the rearing pen than IH (median (IQ) 15% of observations [12-20%] versus 2% [0-13%]; P < 0.05). All animals except one IH initiated contact with the handler during the last sessions of handling (Fisher's exact test, ns). Principal Component Analyses revealed significant effects of rearing and testing conditions on pigs’ behaviour and posture. Novelty led to fewer vocalisations and more exploration for IH than GH animals (P < 0.05), but there were no differences between treatments after habituation to the testing situation. The backs of IH animals were more rounded than those of GH (P < 0.05; dimension 1 of PCA), independently of the test condition. Human presence had no effect on posture. In conclusion, the method based on geometric morphometrics that we developed to study pig posture detected variations in walking posture in pigs associated with rearing conditions. Postures might reflect affective states in pigs, as shown in other species, but further studies are needed to verify thi

Comparison of methods for DMSP measurements in dinoflagellate cultures

International audienceA comparison of three analytical methods (the indirect GC‐FPD and MIMS, and direct LC‐MS/MS) for dimethylsulfoniopropionate (DMSP) measurements was conducted to assess their accuracy and reliability. The three methods showed a linear response but are distinguished by their linearity range, the largest being for MIMS. All three methods showed good precision on Alexandrium minutum samples (2–12%). The variability between the three methods when comparing analyses of A. minutum replicates was 11%, with the DMSP measurements by LC‐MS/MS being the highest. This result also confirms that indirect DMSP measurement after hydrolysis for GC or MIMS methods does not lead to an overestimation of DMSP values in A. minutum . A special focus was made on the more recent LC‐MS/MS method including further assays in sample preparation and storage from cultures of the dinoflagellate A. minutum . Dinoflagellate cells should be harvested by gentle filtration (< 5 cm Hg) or slow centrifugation (500 × g ) to retrieve the largest DMSP pool. For the LC‐MS/MS method, MeOH used for cell extraction should be added prior to freezing (to prevent DMSP degradation). Samples will then be stable in frozen storage for at least 2 months. Finally, direct and indirect methods are complementary for identifying the exact DMSP fraction among dimethylsulfide‐producing compounds that compose total and particulate DMSP pools issued from newly screened organisms or environmental samples

Accuracy of FDG-PET/CT in colorectal peritoneal carcinomatosis: Potential tool for evaluation of chemotherapeutic response

Background/Aim: Neoadjuvant chemotherapy may be administered to patients with peritoneal carcinomatosis (PC) of colorectal cancer (CRC) origin. This study evaluated the performance of 18fluorodeoxyglucose positron-emission tomography (FDG-PET)/computed tomography (CT) in detection of PC from CRC and correlated the most metabolically active quadrant with the most affected peritoneal area determined during surgery. Patients and Methods: This retrospective study compared the performance of FDG-PET/CT for PC diagnosis in 26 patients with CRC with histopathologically-confirmed PC with a control group of 26 patients. An FDG-PET/CT score established for each patient diagnosed with PC was compared with the peritoneal cancer index (PCI) performed during surgery. Results: The sensitivity and specificity of FDG-PET/CT for PC detection were 85% (22/26) and 88% (23/26), respectively. The most scored quadrant by FDGPET/ CT corresponded to the most scored quadrant at surgery in 77.3%. Conclusion: FDG-PET/CT may represent a useful tool for evaluating response to neoadjuvant chemotherapy in patients with PC of CRC origin.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Accuracy of FDG-PET/CT in Colorectal Peritoneal Carcinomatosis: Potential Tool for Evaluation of Chemotherapeutic Response

Background/Aim: Neoadjuvant chemotherapy may be administered to patients with peritoneal carcinomatosis (PC) of colorectal cancer (CRC) origin. This study evaluated the performance of 18fluorodeoxyglucose positron-emission tomography (FDG-PET)/computed tomography (CT) in detection of PC from CRC and correlated the most metabolically active quadrant with the most affected peritoneal area determined during surgery. Patients and Methods: This retrospective study compared the performance of FDG-PET/CT for PC diagnosis in 26 patients with CRC with histopathologically-confirmed PC with a control group of 26 patients. An FDG-PET/CT score established for each patient diagnosed with PC was compared with the peritoneal cancer index (PCI) performed during surgery. Results: The sensitivity and specificity of FDG-PET/CT for PC detection were 85% (22/26) and 88% (23/26), respectively. The most scored quadrant by FDGPET/ CT corresponded to the most scored quadrant at surgery in 77.3%. Conclusion: FDG-PET/CT may represent a useful tool for evaluating response to neoadjuvant chemotherapy in patients with PC of CRC origin.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Resonant Metasurface for Halide Perovskite-Based Emitting Devices: Extraction Efficiency Enhancement and Radiation Pattern on-Demand

National audienc

Multi-resonances for simultaneous enhancement of two-photon absorption and photoluminescence extraction in perovskite metasurface

National audienc

Multi-resonances for simultaneous enhancement of two-photon absorption and photoluminescence extraction in perovskite metasurface

National audienc

Realization of Polaritonic Topological Charge at Room Temperature Using Polariton Bound States in the Continuum from Perovskite Metasurface

International audienceExciton-polaritons are mixed light–matter excitations resulting from the strong coupling regime between an active excitonic material and photonic resonances. Harnessing these hybrid excitations provides a rich playground to explore fascinating fundamental features, as out-of-equilibrium Bose–Einstein condensation and quantum fluids of light, plus novel mechanisms to be exploited in optoelectronic devices. The formation of exciton-polaritons arising from the mixing between hybrid inorganic–organic perovskite excitons and an optical bound state in a continuum (BIC) of a subwavelength-scale metasurface, are experimentally investigated at room temperature. These polaritonic eigenmodes, hereby called polariton BICs (pol-BICs) are revealed in reflectivity, resonant scattering, and photoluminescence measurements. Although pol-BICs only exhibit a finite quality factor bounded by the nonradiative losses of the excitonic component, they fully inherit BIC peculiar features: a full uncoupling from the radiative continuum in the vertical direction, which is associated to a locally vanishing farfield radiation in momentum space. Most importantly, the experimental results confirm that the topological nature of the photonic BIC is perfectly transferred to the pol-BIC. This is evidenced by the observation of a polarization vortex in the farfield of polaritonic emission. The results pave the way to engineer BIC physics of interacting bosons and novel room temperature polaritonic device