RESUMO
The mergers of binary compact objects such as neutron stars and black holes are of central interest to several areas of astrophysics, including as the progenitors of gamma-ray bursts (GRBs)1, sources of high-frequency gravitational waves (GWs)2 and likely production sites for heavy-element nucleosynthesis by means of rapid neutron capture (the r-process)3. Here we present observations of the exceptionally bright GRB 230307A. We show that GRB 230307A belongs to the class of long-duration GRBs associated with compact object mergers4-6 and contains a kilonova similar to AT2017gfo, associated with the GW merger GW170817 (refs. 7-12). We obtained James Webb Space Telescope (JWST) mid-infrared imaging and spectroscopy 29 and 61 days after the burst. The spectroscopy shows an emission line at 2.15 microns, which we interpret as tellurium (atomic mass A = 130) and a very red source, emitting most of its light in the mid-infrared owing to the production of lanthanides. These observations demonstrate that nucleosynthesis in GRBs can create r-process elements across a broad atomic mass range and play a central role in heavy-element nucleosynthesis across the Universe.
RESUMO
PURPOSE: To study the association of clinical factors and optical coherence tomography (OCT) retinal imaging with axial length (AL) and AL growth in preterm infants METHODS: Among a subgroup of infants from the prospective BabySTEPS study who were screened for retinopathy of prematurity (ROP) and had both AL measured and OCT imaging performed, we analyzed data collected prior to 42 weeks postmenstrual age (PMA) and prior to ROP treatment. Using linear mixed effects models, we evaluated associations between AL and AL growth with gestational age (GA), birthweight, PMA, sex, race, multiparity, maximum ROP stage, and OCT features. RESULTS: We included 66 infants (132 eyes), mean GA = 27.6 weeks (SD = 2.3; range: 23.0-34.4) and mean birthweight = 961 g (SD = 269, range: 490-1580). In the final predictive model, longer AL was associated with earlier GA, higher birthweight, later PMA, non-White race, and thicker subfoveal choroid (all p values ≤ 0.01). AL increased linearly up to 42 weeks PMA. There was no difference in AL growth rate by GA, sex, race, multiparity, maximum ROP severity, central foveal thickness, or subfoveal choroidal thickness (all p values > 0.05); but AL growth rate was slower in infants with lower birthweight (p = 0.01). CONCLUSIONS: Among preterm infants, those with earlier GA, higher birthweight, later PMA, non-White race, and thicker subfoveal choroid had the longest AL. AL increased linearly up to 42 weeks PMA and lower birthweight was associated with slower AL growth. These findings may improve the accuracy of measurements taken on preterm infants using imaging techniques affected by AL (e.g., measuring lateral dimensions on OCT). TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT02887157 , date of registration: August 25, 2016.
