24 research outputs found
Astro2020 Must Issue Actionable Recommendations Regarding Diversity, Inclusion, and Harassment
The 2010 Decadal survey failed to issue any recommendations on diversity and inclusion.Astro2020 cannot make the same mistake. Findings can be ignored by funding agencies;recommendations cannot. In the past decade, multiple groups have assembled detailed actionplans to fix a broken climate within our profession. Astro2020 should play a key role, bysynthesizing this work to produce actionable recommendations to support diversity andinclusion and stop harassment within our profession
Heavy element production in a compact object merger observed by JWST
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 mergers 4–6 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
Orbital control on carbon cycle and oceanography in the mid-Cretaceous greenhouse
We established a new high-resolution carbonate carbon isotope record of the Albian interval of the Marne a Fucoidi Formation (Central Apennines, Italy), which was deposited on the southern margin of the western Tethys Ocean. Bulk carbonate sampled with 10–15 cm spacing was used for the construction of a continuous carbon isotope curve through the Albian stage. Spectral analyses reveal prominent 400 kyr cyclicity in the δ13C curve, which correlates with Milankovitch long eccentricity changes. Cycles occurring in our record resemble those observed in several Cenozoic δ13C records, suggesting that a link between orbital forcing and carbon cycling existed also under mid-Cretaceous greenhouse conditions. Based on comparisons with Cenozoic eccentricity-carbon cycle links we hypothesize that 400 kyr cycles in the mid-Cretaceous were related to a fluctuating monsoonal regime, coupled with an unstable oceanic structure, which made the oceanic carbon reservoir sensitive to orbital variations. In the Tethys these oceanographic conditions lasted until the Late Albian, and then were replaced by a more stable circulation mode, less sensitive to orbital forcing
Assessment of endpoint definitions in recurrent and metastatic mucosal head and neck squamous cell carcinoma trials:HNCIG international consensus recommendations
Transparent and precise endpoint definitions are a critical aspect of clinical trial conduct and reporting, and are used to communicate the benefit of an intervention. Previous studies have identified inconsistencies in endpoint definitions in oncological clinical trials. Here, the Head Neck Cancer International Group reports endpoint definitions from trial published between 2008-2021 in phase 3 trials or trials considered potentially practice-changing in the recurrent metastatic setting for patients with mucosal head and neck squamous cell carcinoma. We identify significant and global heterogeneity in endpoint definitions which potentially undermines the interpretation of results and development of future studies. We demonstrate how fundamental components of even seemingly incontrovertible endpoints such as overall survival varies widely, highlighting an urgent need for increased rigor in reporting and harmonisation of endpoint reporting
Assessment of endpoint definitions in recurrent and metastatic mucosal head and neck squamous cell carcinoma trials:HNCIG international consensus recommendations.
Transparent and precise endpoint definitions are a critical aspect of clinical trial conduct and reporting, and are used to communicate the benefit of an intervention. Previous studies have identified inconsistencies in endpoint definitions in oncological clinical trials. Here, the Head Neck Cancer International Group reports endpoint definitions from trial published between 2008-2021 in phase 3 trials or trials considered potentially practice-changing in the recurrent metastatic setting for patients with mucosal head and neck squamous cell carcinoma. We identify significant and global heterogeneity in endpoint definitions which potentially undermines the interpretation of results and development of future studies. We demonstrate how fundamental components of even seemingly incontrovertible endpoints such as overall survival varies widely, highlighting an urgent need for increased rigor in reporting and harmonisation of endpoint reporting
Assessment of endpoint definitions in recurrent and metastatic mucosal head and neck squamous cell carcinoma trials: Head and Neck Cancer International Group consensus recommendations
Transparent and precise endpoint definitions are a crucial aspect of clinical trial conduct and reporting, and are used to communicate the benefit of an intervention. Previous studies have identified inconsistencies in endpoint definitions across oncological clinical trials. Here, the Head and Neck Cancer International Group assessed endpoint definitions from phase 3 trials or trials considered practice-changing for patients with recurrent or metastatic mucosal head and neck squamous cell carcinoma, published between 2008 and 2021. We identify considerable and global heterogeneity in endpoint definitions, which undermines the interpretation of results and development of future studies. We show how fundamental components of even incontrovertible endpoints such as overall survival vary widely, highlighting an urgent need for increased rigour in reporting and harmonisation of endpoints.</p
A kilonova following a long-duration gamma-ray burst at 350 Mpc
Here, we report the discovery of a kilonova associated with the nearby (350
Mpc) minute-duration GRB 211211A. In tandem with deep optical limits that rule
out the presence of an accompanying supernova to mag at 17.7 days
post-burst, the identification of a kilonova confirms that this burst's
progenitor was a compact object merger. While the spectrally softer tail in GRB
211211A's gamma-ray light curve is reminiscent of previous extended emission
short GRBs (EE-SGRBs), its prompt, bright spikes last s,
separating it from past EE-SGRBs. GRB 211211A's kilonova has a similar
luminosity, duration and color to AT2017gfo, the kilonova found in association
with the gravitational wave (GW)-detected binary neutron star (BNS) merger
GW170817. We find that the merger ejected of
r-process-rich material, and is consistent with the merger of two neutron stars
(NSs) with masses close to the canonical . This discovery
implies that GRBs with long, complex light curves can be spawned from compact
object merger events and that a population of kilonovae following GRBs with
durations s should be accounted for in calculations of the NS merger
r-process contribution and rate. At 350 Mpc, the current network of GW
interferometers at design sensitivity would have detected the merger
precipitating GRB 211211A, had it been operating at the time of the event.
Further searches for GW signals coincident with long GRBs are therefore a
promising route for future multi-messenger astronomy.Comment: Submitted. 69 pages, 11 figures, 3 table
Regional Climate Shifts Caused by Gradual Global Cooling in the Pliocene Epoch
The Earth\u27s climate has undergone a global transition over the past four million years, from warm conditions with global surface temperatures about 3 °C warmer than today, smaller ice sheets and higher sea levels to the current cooler conditions. Tectonic changes and their influence on ocean heat transport have been suggested as forcing factors for that transition, including the onset of significant Northern Hemisphere glaciation 2.75 million years ago, but the ultimate causes for the climatic changes are still under debate. Here we compare climate records from high latitudes, subtropical regions and the tropics, indicating that the onset of large glacial/interglacial cycles did not coincide with a specific climate reorganization event at lower latitudes. The regional differences in the timing of cooling imply that global cooling was a gradual process, rather than the response to a single threshold or episodic event as previously suggested. We also find that high-latitude climate sensitivity to variations in solar heating increased gradually, culminating after cool tropical and subtropical upwelling conditions were established two million years ago. Our results suggest that mean low-latitude climate conditions can significantly influence global climate feedbacks