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

Efeito da temperatura e do tegumento na germinação de sementes de Calophyllum brasiliense Effect of temperature and coat in the germination of Calophyllum brasiliense seeds

A crescente demanda por informações de espécies com potencial para serem implantadas em ambientes degradados, torna fundamental o conhecimento fisiológico da germinação de sementes, visando sua exploração mais racional. Objetivou-se neste trabalho, estudar o comportamento da embebição das sementes, determinar a temperatura ótima da germinação e o efeito da retirada de tegumento sobre a germinação de sementes de Calophyllum brasiliense Cambess. O teste de germinação foi realizado em rolos de papel, com quatro repetições de 25 sementes, em delineamento inteiramente casualizado. Os resultados da curva de embebição demonstraram que o envoltório (endocarpo + tegumento) dificulta a absorção de água pela semente. Quanto à temperatura, observou-se uma maior germinabilidade nos regimes térmicos de 30ºC (constante) e 30/20ºC (alternada), sendo que, o maior índice de velocidade de germinação (IVG) também ocorreu a 30ºC. As sementes incubadas a 10ºC, 15ºC e 40ºC não germinaram. Menores valores de tempo médio de germinação foram observados nos regimes térmicos de 30ºC, 30/20ºC e 35ºC. Não foram verificadas diferenças significativas quanto à germinabilidade das sementes com e sem tegumento, porém, o tegumento reduziu a velocidade de germinação.<br>Due to the increasing demand for informations about species with potential for being introduced in degraded environment, it is important the physiological knowledge of seeds germination, aiming their rational exploration. The objective of this research was to evaluate the behaviour of seed imbibition, to determine the germination optimum temperature and the effect of coat seeds withdrawing in the germination of Calophyllum brasiliense Cambess. The germination was performed in paper rolls, with four replicates of 25 seeds each, disposed in a complete randomized design. The results of imbibition curve showed that seed-coat has as hindance for the water absorption by seed. In relation to temperature, it was observed a higher germination percentage at 30ºC (constant) and 30/20ºC (alternate). Higher speed germination index (IVG) was also observed at 30ºC. The seeds incubated at 10ºC, 15ºC and 40ºC did not germinate. The lowest values of germination mean time was at 30ºC, 30/20ºC and 35ºC. No significative differences were verified in relation to germinability with and without tegument, although the tegument reduced the germination rate

Effect of lung recruitment and titrated Positive End-Expiratory Pressure (PEEP) vs low PEEP on mortality in patients with acute respiratory distress syndrome - A randomized clinical trial

IMPORTANCE: The effects of recruitment maneuvers and positive end-expiratory pressure (PEEP) titration on clinical outcomes in patients with acute respiratory distress syndrome (ARDS) remain uncertain. OBJECTIVE: To determine if lung recruitment associated with PEEP titration according to the best respiratory-system compliance decreases 28-day mortality of patients with moderate to severe ARDS compared with a conventional low-PEEP strategy. DESIGN, SETTING, AND PARTICIPANTS: Multicenter, randomized trial conducted at 120 intensive care units (ICUs) from 9 countries from November 17, 2011, through April 25, 2017, enrolling adults with moderate to severe ARDS. INTERVENTIONS: An experimental strategy with a lung recruitment maneuver and PEEP titration according to the best respiratory-system compliance (n = 501; experimental group) or a control strategy of low PEEP (n = 509). All patients received volume-assist control mode until weaning. MAIN OUTCOMES AND MEASURES: The primary outcome was all-cause mortality until 28 days. Secondary outcomes were length of ICU and hospital stay; ventilator-free days through day 28; pneumothorax requiring drainage within 7 days; barotrauma within 7 days; and ICU, in-hospital, and 6-month mortality. RESULTS: A total of 1010 patients (37.5% female; mean [SD] age, 50.9 [17.4] years) were enrolled and followed up. At 28 days, 277 of 501 patients (55.3%) in the experimental group and 251 of 509 patients (49.3%) in the control group had died (hazard ratio [HR], 1.20; 95% CI, 1.01 to 1.42; P = .041). Compared with the control group, the experimental group strategy increased 6-month mortality (65.3% vs 59.9%; HR, 1.18; 95% CI, 1.01 to 1.38; P = .04), decreased the number of mean ventilator-free days (5.3 vs 6.4; difference, −1.1; 95% CI, −2.1 to −0.1; P = .03), increased the risk of pneumothorax requiring drainage (3.2% vs 1.2%; difference, 2.0%; 95% CI, 0.0% to 4.0%; P = .03), and the risk of barotrauma (5.6% vs 1.6%; difference, 4.0%; 95% CI, 1.5% to 6.5%; P = .001). There were no significant differences in the length of ICU stay, length of hospital stay, ICU mortality, and in-hospital mortality. CONCLUSIONS AND RELEVANCE: In patients with moderate to severe ARDS, a strategy with lung recruitment and titrated PEEP compared with low PEEP increased 28-day all-cause mortality. These findings do not support the routine use of lung recruitment maneuver and PEEP titration in these patients. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT01374022