Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Multi-messenger Observations of a Binary Neutron Star Merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ∼ 1.7 {{s}} with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of {40}-8+8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 {M}ȯ . An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ∼ 40 {{Mpc}}) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ∼ 9 and ∼ 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.</p

Intérêt du cultivar « Bronowski » pour l'obtention de plantes mâle-stériles cytoplasmiques chez le colza (Brassica napus L.)

International audienc

Premiers résultats d'un programme d'introduction de l'androstérilité « Ogura » du radis chez le colza

International audienc

N° 101. — Étude électrochimique et préparative de l’eau oxygénée et des peroxydes minéraux

En présence de certains cations (Mg2+, Mn2+) la vague de réduction polarograpliique de l’eau oxygénée se dédouble. Ce comportement est attribué à la formation de peroxydes ou d’hydroperoxydes du cation dédoublant à partir de l’hydroxyde de ce dernier précipité à la surface de la goutte. L’allure des courbes chronoampérométriques est caractéristique d’un phénomène d’inhibition. Nous rendons compte de l’évolution de l’intensité relalive des deux courants en fonction de la concentration en cation actif et nous proposons un mécanisme global pour la réduction de l’eau oxygénée dans ces conditions.Les résultats obtenus, lorsque l’on essaie de mettre en évidence la formation de peroxydes par électrolyse sur une cathode à grande surface, constituent une preuve du mécanisme proposé

Genetic and molecular approaches to improve nutritional value of Brassica napus L. seed

International audienceOilseed rape (Brassica napus L.) is a major oil crop that also supplies proteins for the feed industry. In order to reduce total cost production, the objective is to increase oil yield while reducing crop inputs (especially nitrogen and pesticides). Concomitantly, it is necessary to anticipate specific uses (e.g., fatty acid composition) and to ensure the valorisation of the by-products (rapeseed meal). By the past, improvement of seed quality focused on fatty acid balance and low seed glucosinolate content. Current goals include the breeding of yellow-seeded rapeseed lines with high content of seed oil. The use of molecular tools and the exploitation of Arabidopsis knowledge will be presented and discussed

Étude électrochimique et préparative de l’eau oxygénée et des peroxydes minéraux

Le cation La3+ perturbe, d’une façon très complexe, le processus de réduction de H2O2. Un petit pic, déjà signalé, apparaît à + 0,17 volt; il est suivi par la vague principale qui présente un front vertical; l’intensité de cette vague est limitée par un phénomène d’inhibition comme l’indique l’allure des courbes i — t.Le front vertical est attribué à un phénomène de réduction autocatalytique. Les espèces actives seraient des hydroxo- complexes à charge élevée, formés par réaction entre les cations La3+ et les ions OH- produits par la réduction de H2O2. L’étude de l’influence de différents facteurs, dont le pH, ainsi que l’allure exponentielle d’une partie de la courbe i — t, s’interprètent très bien avec cette théorie.L’origine du phénomène inhibiteur a été recherchée par l’étude de la chimie du système (La3+, OH-, H2O2). Il est attribué à la formation, sur la surface de la goutte, d’un hydroperoxyde de lanthane.Les hypothèses, qui pourraient expliquer la présence du pic à + 0,17 volt, sont exposées, mais aucune ne donne entière satisfaction

Detection of Methanobrevobacter smithii and Methanobrevibacter oralis in Lower Respiratory Tract Microbiota

Methanogens, the sole microbes producing methane, are archaea commonly found in human anaerobic microbiota. Methanogens are emerging as opportunistic pathogens associated with dysbiosis and are also detected and cultured in anaerobic abscesses. Their presence in the respiratory tract is yet unknown. As a preliminary answer, prospective investigation of 908 respiratory tract samples using polyphasic approach combining PCR-sequencing, real-time PCR, fluorescent in situ hybridization (FISH), and methanogens culture was carried out. Methanobrevibacter smithii and Methanobrevibacter oralis DNA sequences, were detected in 21/527 (3.9%) sputum samples, 2/188 (1.06%) bronchoalveolar lavages, and none of 193 tracheo-bronchial aspirations. Further, fluorescence in situ hybridization detected methanogens in three sputum investigated specimens with stick morphology suggesting M. oralis and in another one bronchoalveolar lavage sample investigated, diplococal morphology suggesting M. smithii. These observations extend the known territory of methanogens to the respiratory tract and lay the foundations for further interpretation of their detection as pathogens in any future cases of isolation from bronchoalveolar lavages and the lungs