Mass extinction at the Cretaceous–Paleogene (K-Pg) boundary coincides with the Chicxulub bolide impact and also falls within the broader time frame of Deccan trap emplacement. Critically, though, ...empirical evidence as to how either of these factors could have driven observed extinction patterns and carbon cycle perturbations is still lacking. Here, using boron isotopes in foraminifera, we document a geologically rapid surface-ocean pH drop following the Chicxulub impact, supporting impact-induced ocean acidification as amechanism for ecological collapse in the marine realm. Subsequently, surface water pH rebounded sharply with the extinction of marine calcifiers and the associated imbalance in the global carbon cycle. Our reconstructed water-column pH gradients, combined with Earth system modeling, indicate that a partial ∼50% reduction in global marine primary productivity is sufficient to explain observed marine carbon isotope patterns at the K-Pg, due to the underlying action of the solubility pump. While primary productivity recovered within a few tens of thousands of years, inefficiency in carbon export to the deep sea lasted much longer. This phased recovery scenario reconciles competing hypotheses previously put forward to explain the K-Pg carbon isotope records, and explains both spatially variable patterns of change in marine productivity across the event and a lack of extinction at the deep sea floor. In sum, we provide insights into the drivers of the last mass extinction, the recovery of marine carbon cycling in a postextinction world, and the way in which marine life imprints its isotopic signal onto the geological record.
Falling atmospheric CO₂ levels led to cooling through the Eocene and the expansion of Antarctic ice sheets close to their modern size near the beginning of the Oligocene, a period of poorly ...documented climate. Here, we present a record of climate evolution across the entire Oligocene (33.9 to 23.0 Ma) based on TEX86 sea surface temperature (SST) estimates from southwestern Atlantic Deep Sea Drilling Project Site 516 (paleolatitude ∼36°S) and western equatorial Atlantic Ocean Drilling Project Site 929 (paleolatitude ∼0°), combined with a compilation of existing SST records and climate modeling. In this relatively low CO₂ Oligoceneworld (∼300 to 700 ppm),warm climates similar to those of the late Eocene continued with only brief interruptions, while the Antarctic ice sheet waxed and waned. SSTs are spatially heterogenous, but generally support late Oligocene warming coincident with declining atmospheric CO₂. This Oligocene warmth, especially at high latitudes, belies a simple relationship between climate and atmospheric CO₂ and/or ocean gateways, and is only partially explained by current climate models. Although the dominant climate drivers of this enigmatic Oligocene world remain unclear, our results help fill a gap in understanding past Cenozoic climates and the way long-term climate sensitivity responded to varying background climate states.
We reconstruct sea surface temperatures (SSTs) at Deep Sea Drilling Project Site 608 (42.836°N, 23.087°), north of the Azores Front, and Ocean Drilling Program Site 982 (57.516°N, 15.866°), under the ...North Atlantic Current, in order to track Miocene (23.1–5.3 Ma) development of North Atlantic surface waters. Mean annual SSTs from TEX86 and UK′37 proxy estimates at both sites were 10–15 °C higher than modern through the Miocene Climatic Optimum (17–14.5 Ma). During the global cooling of the Middle Miocene Climate Transition (~14.5–12.5 Ma), SSTs at midlatitude Site 608 cooled by ~6 °C, whereas high‐latitude Site 982 cooled by only ~2 °C, resulting in an ~4 Myr collapse of the SST gradient between the two sites. This regional pattern is inconsistent with an increased latitudinal surface temperature gradient, as generally associated with global cooling episodes linked to decreasing pCO2 levels. Instead, the pattern is best explained by enhanced ocean heat transport into the high‐latitude North Atlantic superimposed on the global cooling trend, probably due to enhanced Atlantic meridional overturning circulation and/or a stronger North Atlantic Current. During global late Miocene cooling (~8–7 Ma), surface waters cooled by ~6 °C at Site 982 while minimal change occurred at Site 608, reestablishing the North Atlantic SST gradient. The collapse and reemergence of the SST gradient between the middle‐ and high‐latitude North Atlantic suggests that interaction between changes in regional ocean circulation and the global response to changes in greenhouse gas concentration was important in Miocene climate evolution.
Key Points
Biomarker estimated North Atlantic sea surface temperature was 10–15 °C warmer than modern during Miocene Climatic Optimum (17–14.5 Ma)
Surface temperature gradient from middle‐ to high‐latitude North Atlantic collapsed for ~4 Myr following global cooling starting at ~14.5 Ma
Ocean heat transport to the high‐latitude North Atlantic increased at ~14 Ma, likely due to oceanic gateway or ocean circulation changes
Arctic climate in the Late Cretaceous has long been recognized to have been warm and wet relative to the present, but quantitative assessments of paleoclimate have been challenging due, in part, to ...disagreements between proxies in marine and terrestrial environments. This study provides a first multiproxy evaluation of Late Cretaceous (~93–90 Ma to 73–72 Ma) paleoclimate and paleohydrology from Devon Island in the Canadian High Arctic (modern location: 76°17′N, 91°12′W; Late Cretaceous location: ~71°30′N, ~24°30′W). Surface temperatures are reconstructed at ~12.6 to 20.6 °C for the ocean and 11.7 to 16.9 °C over land, using glycerol dialkyl glycerol tetraether (GDGT) based proxies measured from marine (TEX86) and terrestrial samples (MBT′5ME). These proxies are likely skewed toward warm month temperatures, based on novel analysis and interpretation of biomarkers in sediment and co-occurring marine vertebrate coprolites. The hydrogen isotopic composition (δ2H) of precipitation is constrained to have varied from −123‰ to −82‰ (VSMOW) using evidence from n-alkanes likely derived from higher plants. δ18O of shelfal marine surface water is constrained to have been between −10.5‰ to −3.4‰, using phosphate oxygen isotopes of marine vertebrate teeth and coprolites. From these, marine salinity is modeled to have varied from 10 PSU and 30 PSU, indicative of periodic freshwater influx. These estimates indicate that large marine vertebrates lived and fed, at least intermittently, in near-shore brackish waters. Finally, the Arctic was similarly warm in both the Late Cretaceous and Paleocene/Eocene, but the Late Cretaceous isotopic composition of precipitation at Devon Island was enriched in the heavy isotope of hydrogen by up to +60 to +70‰ relative to Arctic Eocene sites. The combination of techniques used here reduces uncertainties related to the application of proxies to an environment without a modern analogue, providing novel paleoclimatic constraints on the Late Cretaceous Arctic region.
•Arctic TEX86 sea surface temperatures of ~13–21 °C in Late Cretaceous•MBT′5ME terrestrial temperature estimates of ~12–17 °C•Warm month bias of TEX86 suggested by biomarker analysis of marine coprolites•Neritic salinity highly variable (10–30 PSU)•Isotopic composition of precipitation highly enriched relative to modern
Manifesto for new directions in developmental science Barbot, Baptiste; Hein, Sascha; Trentacosta, Christopher ...
New directions for child and adolescent development,
July 2020, Letnik:
2020, Številka:
172
Journal Article
Recenzirano
Odprti dostop
Although developmental science has always been evolving, these times of fast‐paced and profound social and scientific changes easily lead to disorienting fragmentation rather than coherent scientific ...advances. What directions should developmental science pursue to meaningfully address real‐world problems that impact human development throughout the lifespan? What conceptual or policy shifts are needed to steer the field in these directions? The present manifesto is proposed by a group of scholars from various disciplines and perspectives within developmental science to spark conversations and action plans in response to these questions. After highlighting four critical content domains that merit concentrated and often urgent research efforts, two issues regarding “how” we do developmental science and “what for” are outlined. This manifesto concludes with five proposals, calling for integrative, inclusive, transdisciplinary, transparent, and actionable developmental science. Specific recommendations, prospects, pitfalls, and challenges to reach this goal are discussed.
Recurrent chromosomal rearrangements have not been well characterized in common carcinomas. We used a bioinformatics approach to discover candidate oncogenic chromosomal aberrations on the basis of ...outlier gene expression. Two ETS transcription factors, ERG and ETV1, were identified as outliers in prostate cancer. We identified recurrent gene fusions of the 5' untranslated region of TMPRSS2 to ERG or ETV1 in prostate cancer tissues with outlier expression. By using fluorescence in situ hybridization, we demonstrated that 23 of 29 prostate cancer samples harbor rearrangements in ERG or ETV1. Cell line experiments suggest that the androgen-responsive promoter elements of TMPRSS2 mediate the overexpression of ETS family members in prostate cancer. These results have implications in the development of carcinomas and the molecular diagnosis and treatment of prostate cancer.
Restarting elective services presents a challenge to restore and improve many of the planned patient care pathways which have been suspended during the response to the COVID-19 pandemic. A ...significant backlog of planned elective work has built up representing a considerable volume of patient need. We aimed to investigate the health status, quality of life, and the impact of delay for patients whose referrals and treatment for symptomatic joint arthritis had been delayed as a result of the response to COVID-19.
We interviewed 111 patients referred to our elective outpatient service and whose first appointments had been cancelled as a result of the response to the COVID-19 pandemic.
Patients reported significant impacts on their health status and quality of life. Overall, 79 (71.2%) patients reported a further deterioration in their condition while waiting, with seven (6.3%) evaluating their health status as 'worse than death'.
Waiting lists are clearly not benign and how to prioritize patients, their level of need, and access to assessment and treatment must be more sophisticated than simply relying on the length of time a patient has been waiting. This paper supports the contention that patients awaiting elective joint arthroplasty report significant impacts on their quality of life and health status. This should be given appropriate weight when patients are prioritized for surgery as part of the recovery of services following the COVID-19 pandemic. Elective surgery should not be seen as optional surgery-patients do not see it in this way.
Acute kidney injury (AKI) is a common complication of hospitalisations. This national audit assessed the care received by patients with AKI in hospital Trusts in England and Wales.
Twenty four ...hospital Trusts across England and Wales took part. Patients with AKI stage2/3 were identified using the UK Renal Registry AKI master patient index. Data was returned through a secure portal with linkage to hospital episode statistic mortality and hospitalisation data. Completion rates of AKI care standards and regional variations in care were established.
989 AKI episodes were included in the analyses. In-hospital 30-day mortality was 31-33.1% (AKI 2/3). Standard AKI interventions were completed in >80% of episodes. Significant inter-hospital variation remained in attainment of AKI care standards after adjustment for age and sex. Recording of urinalysis (41.9%) and timely imaging (37.2%) were low. Information on discharge summaries relating to medication changes/re-commencement and follow-up blood tests associated with reduced mortality. No quality indicators relating to clinical management associated with mortality. Better communication on discharge summaries associated with reduced mortality.
Outcomes for patients with AKI in hospital remain poor. Regional variation in care exists. Work is needed to assess whether improving and standardising care improves patient outcomes.
Abstract
Background
Symptomatic gallstones are common. Ursodeoxycholic acid (UDCA) is a bile acid that dissolves gallstones. There is increasing interest in UDCA for symptomatic gallstones, ...particularly in those unfit for surgery.
Method
A UK clinician survey of use and opinions about UDCA in symptomatic gallstones was performed, assessing clinicians’ beliefs and perceptions of UDCA effectiveness. A systematic review was performed in accordance with the PRISMA guidelines. PubMed, MEDLINE, and Embase databases were searched for studies of UDCA for symptomatic gallstones (key terms included ‘ursodeoxycholic acid’; ‘UDCA’; ‘biliary pain’; and ‘biliary colic’). Information was assessed by two authors, including bias assessment, with independent review of conflicts.
Results
Overall, 102 clinicians completed the survey, and 42 per cent had previous experience of using UDCA. Survey responses demonstrated clinical equipoise surrounding the benefit of UDCA for the management of symptomatic gallstones, with no clear consensus for benefit or non-benefit; however, 95 per cent would start using UDCA if there was a randomized clinical trial (RCT) demonstrating a benefit. Eight studies were included in the review: four RCTs, three prospective studies, and one retrospective study. Seven of eight studies were favourable of UDCA for biliary pain. Outcomes and follow-up times were heterogenous, as well as comparator type, with only four of eight studies comparing with placebo.
Conclusion
Evidence for UDCA in symptomatic gallstones is scarce and heterogenous. Clinicians currently managing symptomatic gallstone disease are largely unaware of the benefit of UDCA, and there is clinical equipoise surrounding the benefit of UDCA. Level 1 evidence is required by clinicians to support UDCA use in the future.
Ursodeoxycholic acid (UDCA) may be beneficial for patients with symptomatic gallstone disease; however, current evidence is heterogenous. Clinicians currently managing symptomatic gallstone disease are largely unaware of the benefit of UDCA, and there is clinical equipoise surrounding the benefit of UDCA. Level 1 evidence is required by clinicians to support UDCA use in the future.
The design and conduct of HIPLEX-1, a randomized seeding experiment carried out on small cumulus congestus clouds in eastern Montana, are outlined. The seeding agent was dry ice, introduced in an ...effort to produce microphysical effects, especially the earlier formation of precipitation in the seeded clouds. The earlier formation was expected to increase both the probability and the amount of precipitation from those small clouds with short lifetimes. The experimental unit selection procedure, treatment and randomization procedures, the physical hypothesis, measurement procedures and the response variables defined for the experiment are discussed. Procedures used to calculate the response variables from aircraft and radar measurements are summarized and the values of those variables for the 20 HIPLEX-1 test cases from 1979 and 1980 are tabulated.
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