Association Between COVID-19 and Mortality in Hip Fracture Surgery in the National COVID Cohort Collaborative (N3C): A Retrospective Cohort Study

BACKGROUND: This study investigated the outcomes of coronavirus disease (COVID-19)-positive patients undergoing hip fracture surgery using a national database. METHODS: This is a retrospective cohort study comparing hip fracture surgery outcomes between COVID-19 positive and negative matched cohorts from 46 sites in the United States. Patients aged 65 and older with hip fracture surgery between March 15 and December 31, 2020, were included. The main outcomes were 30-day all-cause mortality and all-cause mortality. RESULTS: In this national study that included 3303 adults with hip fracture surgery, the 30-day mortality was 14.6% with COVID-19-positive versus 3.8% in COVID-19-negative, a notable difference. The all-cause mortality for hip fracture surgery was 27.0% in the COVID-19-positive group during the study period. DICUSSION: We found higher incidence of all-cause mortality in patients with versus without diagnosis of COVID-19 after undergoing hip fracture surgery. The mortality in hip fracture surgery in this national analysis was lower than other local and regional reports. The medical community can use this information to guide the management of hip fracture patients with a diagnosis of COVID-19

Woody cover and hominin environments in the past 6 million years

The role of African savannahs in the evolution of early hominins has been debated for nearly a century. Resolution of this issue has been hindered by difficulty in quantifying the fraction of woody cover in the fossil record. Here we show that the fraction of woody cover in tropical ecosystems can be quantified using stable carbon isotopes in soils. Furthermore, we use fossil soils from hominin sites in the Awash and Omo-Turkana basins in eastern Africa to reconstruct the fraction of woody cover since the Late Miocene epoch (about 7 million years ago). 13 C/ 12 C ratio data from 1,300 palaeosols at or adjacent to hominin sites dating to at least 6 million years ago show that woody cover was predominantly less than 40% at most sites. These data point to the prevalence of open environments at the majority of hominin fossil sites in eastern Africa over the past 6 million years. There is long-standing debate as to the importance of woody versus herbaceous cover in the evolution of humans over the past 6 million years (Myr) Stable carbon isotopes in palaeosols are a key means of reconstructing ancient environments, particularly those in the tropics in the past 6 Myr or longer. Woody plants, almost all of which use the C 3 photosynthetic pathway, would have provided mammals with shade and shelter from the direct sun Calibrating a 'palaeo-shade' proxy We report results of woody cover measurements and th

Woody cover and hominin environments in the past 6 million years

The role of African savannahs in the evolution of early hominins has been debated for nearly a century. Resolution of this issue has been hindered by difficulty in quantifying the fraction of woody cover in the fossil record. Here we show that the fraction of woody cover in tropical ecosystems can be quantified using stable carbon isotopes in soils. Furthermore, we use fossil soils from hominin sites in the Awash and Omo-Turkana basins in eastern Africa to reconstruct the fraction of woody cover since the Late Miocene epoch (about 7 million years ago). 13C/12C ratio data from 1,300 palaeosols at or adjacent to hominin sites dating to at least 6 million years ago show that woody cover was predominantly less than ~40% at most sites. These data point to the prevalence of open environments at the majority of hominin fossil sites in eastern Africa over the past 6 million years

Environmental Controls on the Stable Carbon Isotopic Composition of Soil Organic Carbon: Implications for Modelling the Distribution of C3 and C4 plants, Australia

We use multivariate statistics to examine the continental-scale patterns of the stable carbon isotopic composition (δ13C) of soil organic carbon (SOC) from a data set collected throughout the natural range of variation in climatic, edaphic and biotic controls in Australia. Climate and soil texture (percent of mineral particles \u3c63 μm) are found to be the dominant controls on δ13CSOC. Of the environmental variables analysed, the strongest correlations to δ13CSOC do not simply occur with respect to mean annual temperature or precipitation, but rather to ecosystem-scale measures of water availability such as mean annual vapour pressure deficit (VPD) and an index of the annual flux of available water available to plants (W). After the variance of δ13CSOC attributed to W was removed, the proportion of particles ≤63 μm diameter remained the only secondarily significant correlation (p \u3c 0.05). Based on this observation, we also develop a model of the primary climatic control on δ13CSOC, which is rooted in the assumption of optimized water-use efficiency of C3 and C4 vegetation, and can be extrapolated to continental or global data with readily available environmental data. The model describes optimized water-use efficiency controls on δ13CSOC in terms of a function of the variable W. We estimate model parameters of climatic control on δ13CSOC using an analysis of surface samples (0–5 cm) of sandy soils (\u3c10% mineral particles ≤63 μm diameter) from which other edaphic and biotic controls are minimized. This simple model function is modified to account for variation of δ13CSOC due to variation of respiration rates and variable incorporation of the terrestrial Suess effect with mean annual temperature (MAT). Model regression of δ13CSOC to these continental-scale climate data accounts for 92% of the variance observed using a model function with simple variables (W and MAT) and physically meaningful constants. We also examine edaphic controls on δ13CSOC using particle size separates from soil textural gradients within four climatic zones of Australia. These data indicate the protection of 13C-enriched old, stable SOC in association with fine mineral particles, consistent with variable incorporation of the terrestrial Suess effect