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

THE ROLE OF SEED COAT IN EARLY STAGES OF SOYBEAN GERMINATION

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Effects of shading and removal of plant parts on growth of Trema micrantha seedlings

Effects of artificial shading and removal of plant par ts on growth of Trema mictantha (L.) Blume (Ulmaceae) seedlings were studied. Seedlings were grown in pots in a greenhouse in 45, 30, 10.6, 4.8 and 1.8% of full sunlight. Shading for 60 days had no effect on survival, but it influenced all growth parameters measured. Total biomass decreased with decreasing irradiance, reflecting reductions in dry mass of leaves, stems and roots. In response to shading, allocation of biomass to leaves increased, while allocation of biomass to roots decreased. Specific leaf area, leaf area ratio and leaf mass ratio increased with decreasing irradiance. Decreases in relative growth rate were caused by reductions in net assimilation rate rather than leaf area ratio. Photosynthetic efficiency, as determined by the F-v/F-m ratio (F-v = variable fluorescence, F-m = maximal fluorescence), was unaffected by the shading treatments. Partial removal of leaves, stem or roots did not affect seedling survival. Seedlings responded to removal of plant parts by compensatory growth. Topophysis was observed when the apex was removed: the lateral buds developed only as new plagiotropic lateral shoots; consequently, the decapitated plant ceased height growth and was unable to compete with its neighbors for light.211657

Seedling growth of understorey species of a southeast Brazilian tropical forest

Thirteen understorey species of a mesophyllous tropical forest were studied tinder two different photosynthetic photon flux densities (PPFD). Seedlings were grown in the glasshouse tinder 51% and 2.6% solar PPFD. Growth of the seedlings was evaluated by 1-) total height; 2-) leaf number; 3-) leaf dry mass; 4-) stem dry mass; 5-) root dry mass: 6-) stein length/mass; 7-) shoot/root mass; 8-) percent allocation to leaf stein and roots. For most of the parameters recorded, low PPFD drastically reduced growth. It seemed that the strategy of these understorey species was a reduction of growth under low PPFD saving energy for survival.46469770

PROPAGATION AND FLOWERING IN DESMODIUM-BARBATUM

Flowering in D. barbatum was studied under different photoperiods in order to determine the critical day-length and different number of inductive cycles. The fastest method to produce new plants was also studied. According to the results, D. barbatum is a short-day plant for flowering with a critical day-length between eleven and twelve hours. Shortening the photoperiod enhanced the percentage of flowering plants and increased the number of inflorescences per plant. Cuttings of D. barbatum root very easily. High percentages of rooting were obtained from cuttings taken at different places from the stems and with different number of leaves. Auxin also did not stimulate rooting of the cuttings.27463163

INHIBITION OF ROOTING IN BEAN LEAF CUTTINGS BY THE PULVINUS

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CHANGES IN THE GROWTH-PATTERN OF EICHHORNIA-CRASSIPES (MART) SOLMS LEAVES CAUSED BY GROWTH-REGULATORS

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ROOTING OF DETACHED LEAVES OF PERESKIA-GRANDIFOLIA HARS (CACTACEAE)

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