Summer CO2 evasion from streams and rivers in the Kolyma River basin, north-east Siberia

Inland water systems are generally supersaturated in carbon dioxide (CO2) and are increasingly recognized as playing an important role in the global carbon cycle. The Arctic may be particularly important in this respect, given the abundance of inland waters and carbon contained in Arctic soils; however, a lack of trace gas measurements from small streams in the Arctic currently limits this understanding.We investigated the spatial variability of CO2 evasion during the summer low-flow period from streams and rivers in the northern portion of the Kolyma River basin in north-eastern Siberia. To this end, partial pressure of carbon dioxide (pCO2) and gas exchange velocities (k) were measured at a diverse set of streams and rivers to calculate CO2 evasion fluxes. We combined these CO2 evasion estimates with satellite remote sensing and geographic information system techniques to calculate total areal CO2 emissions. Our results show that small streams are substantial sources of atmospheric CO2 owing to high pCO2 and k, despite being a small portion of total inland water surface area. In contrast, large rivers were generally near equilibrium with atmospheric CO2. Extrapolating our findings across the Panteleikha-Ambolikha sub-watersheds demonstrated that small streams play a major role in CO2 evasion, accounting for 86% of the total summer CO2 emissions from inland waters within these two sub-watersheds. Further expansion of these regional CO2 emission estimates across time and space will be critical to accurately quantify and understand the role of Arctic streams and rivers in the global carbon budget

Repeat antenatal betamethasone and cardiometabolic outcomes

BACKGROUND: Repeat dose(s) of antenatal betamethasone are recommended for women at <32 weeks with ongoing risk of preterm birth. However, there is concern that use of repeat dose(s) in fetal growth restriction (FGR) may increase the risk of later cardiometabolic disease. METHODS: We undertook secondary analysis of data from the Australasian Collaborative Trial of Repeat Doses of Corticosteroids Midchildhood Outcome Study to determine if FGR influences the effect of repeat betamethasone on growth and cardiometabolic function. At 6 to 8 years, children underwent anthropometry, dual energy x-ray absorptiometry, intravenous glucose tolerance testing, ambulatory blood pressure monitoring, and spirometry. FGR was defined as severe FGR at entry, cesarean delivery for FGR, or customized birth weight below the third centile. RESULTS: Of 266 children assessed, FGR occurred in 43 of 127 (34%) exposed to repeat betamethasone and 44 of 139 (32%) exposed to placebo. There was an interaction between FGR and repeat betamethasone treatment for the effect on height (z score mean difference [95% confidence interval]; FGR: 0.59 [0.01 to 1.17]; non-FGR: −0.29 [−0.69 to 0.10]; P = .01). However, FGR did not influence the effect of repeat betamethasone on cardiometabolic function, which was similar in treatment groups, both in FGR and non-FGR subgroups. CONCLUSIONS: Repeat antenatal betamethasone treatment had no adverse effects on cardiometabolic function, even in the presence of FGR. It may have a positive effect on height in FGR. Clinicians should use repeat doses of antenatal corticosteroids when indicated before preterm birth, regardless of FGR, in view of the associated neonatal benefits.Robert D. Cartwright, Jane E. Harding, Caroline A. Crowther, Wayne S. Cutfield, Malcolm R. Battin, Stuart R. Dalziel, Christopher J.D. McKinlay, on behalf of the ACTORDS Follow-up Grou

Repeat antenatal betamethasone and cardiometabolic outcomes

Antenatal corticosteroid therapy is one of the most effective interventions for preterm birth, resulting in rapid maturation of fetal organ systems. The Australasian Collaborative Trial of Repeat Doses of Steroids (ACTORDS) revealed that neonatal benefit is greatest when antenatal corticosteroids are administered in repeat doses, which can be used to reduce the incidence and severity of preterm lung disease and other serious neonatal morbidity, with absolute benefits similar to that of an initial course of antenatal corticosteroids.Robert D. Cartwright, Jane E. Harding, Caroline A. Crowther, Wayne S. Cutfield, Malcolm R. Battin, Stuart R. Dalziel, Christopher J.D. McKinlay, on behalf of the ACTORDS Follow-up Grou

Asteroid close encounters characterization using differential algebra: the case of Apophis

A method for the nonlinear propagation of uncertainties in Celestial Mechanics based on differential algebra is presented. The arbitrary order Taylor expansion of the flow of ordinary differential equations with respect to the initial condition delivered by differential algebra is exploited to implement an accurate and computationally efficient Monte Carlo algorithm, in which thousands of pointwise integrations are substituted by polynomial evaluations. The algorithm is applied to study the close encounter of asteroid Apophis with our planet in 2029. To this aim, we first compute the high order Taylor expansion of Apophis’ close encounter distance from the Earth by means of map inversion and composition; then we run the proposed Monte Carlo algorithm to perform the statistical analysis