The amount and timing of snow cover control the cycling of carbon (C), water, and energy in arctic ecosystems. The implications of changing snow cover for regional C budgets, biogeochemistry, hydrology, and albedo due to climate change are rudimentary, especially for the High Arctic. In a polar semidesert of NW Greenland, we used a ~10-year old snow manipulation experiment to quantify how deeper snow affects magnitude, seasonality, and 14C content of summer C emissions. We monitored ecosystem respiration (Reco), soil CO2, and their 14C contents over three summers in vegetated and bare areas. Additional snowpack, elevated soil water content (SWC), and temperature throughout the growing season in vegetated, but not in bare, areas. Daily Reco was positively correlated to temperature, but negatively correlated to SWC; consequently, we found no effect of increased snow on daily flux. Cumulative summertime Reco was not related to annual snowfall, but to water year precipitation (winter snow plus summer rain). Experimentally increased snowpack shortened the growing season length and reduced summertime Reco up to 40%. Soil CO2 was older under increased snow. However, we found no effect of snow depth on the R eco age because older C emissions were masked by younger CO 2 produced from the litter layer or plant respiration. In the High Arctic, anticipated changes in precipitation regime associated with warming are a key uncertainty for understanding future C cycling. In polar semideserts, water year precipitation is an important driver of summertime Reco. Permafrost C is vulnerable to changes in snowpack, with a deeper snowpack-promoting decomposition of older soil C. ©2014. American Geophysical Union. All Rights Reserved.

Background Surgical stress may cause immunosuppression especially in patients who have surgery for primary tumor removed. This study aimed to explore the effects of dexmedetomidine on immune and inflammatory response in patients undergoing radical gastrectomy. Methods After the institutional review board approval and written informed consent, forty patients undergoing radical gastrectomy were equally randomized to receive dexmedetomidine infusion (Dex group; 0.5 μg·kg-1 initial dose followed by a maintenance dose of 0.4 μg·kg-1 h-1) or normal saline infusion (NS group). Helper T lymphocytes (T helper 1 [Th1] and T helper 2 [Th2]), tumor necrosis factor-α, and interleukin-6 were measured during and after surgeries. Plasma catecholamine levels were also measured during surgery. Postoperative pain was measured by a visual analog scale. Results The percentage of Th1 increased significantly at the end of surgery, 24 h after surgery (P = 0.045 and 0.048, respectively), and Th2 decreased notably at the end of surgery in the Dex group (P = 0.030). Plasma levels of tumor necrosis factor-α (P = 0.045 and 0.036, respectively) and interleukin-6 (P = 0.049 and 0.042, respectively) differed significantly at the end of surgery and 24 h after surgery. Plasma epinephrine and norepinephrine levels decreased significantly at the beginning of surgery in the Dex group (P = 0.020 and 0.015, respectively). At the end of surgery, plasma dopamine levels decreased significantly in the Dex group (P = 0.048), but increased in the NS group. The visual analog scale pain score was lower in the Dex group than in the NS group 24 h after surgery (P = 0.046). Conclusions Dexmedetomidine has been shown to reduce surgical stresses and maintain Th1/Th2 balance. It has been shown to reduce inflammatory responses and exerts immunoprotective effect.

Objective To compare the expected probability of pregnancy after hysteroscopic versus laparoscopic sterilization based on available data using decision analysis. Study design We developed an evidence-based Markov model to estimate the probability of pregnancy over 10 years after three different female sterilization procedures: hysteroscopic, laparoscopic silicone rubber band application and laparoscopic bipolar coagulation. Parameter estimates for procedure success, probability of completing follow-up testing and risk of pregnancy after different sterilization procedures were obtained from published sources. Results In the base case analysis at all points in time after the sterilization procedure, the initial and cumulative risk of pregnancy after sterilization is higher in women opting for hysteroscopic than either laparoscopic band or bipolar sterilization. The expected pregnancy rates per 1000 women at 1 year are 57, 7 and 3 for hysteroscopic sterilization, laparoscopic silicone rubber band application and laparoscopic bipolar coagulation, respectively. At 10 years, the cumulative pregnancy rates per 1000 women are 96, 24 and 30, respectively. Sensitivity analyses suggest that the three procedures would have an equivalent pregnancy risk of approximately 80 per 1000 women at 10 years if the probability of successful laparoscopic (band or bipolar) sterilization drops below 90% and successful coil placement on first hysteroscopic attempt increases to 98% or if the probability of undergoing a hysterosalpingogram increases to 100%. Conclusion Based on available data, the expected population risk of pregnancy is higher after hysteroscopic than laparoscopic sterilization. Consistent with existing contraceptive classification, future characterization of hysteroscopic sterilization should distinguish "perfect" and "typical" use failure rates. Implications Pregnancy probability at 1 year and over 10 years is expected to be higher in women having hysteroscopic as compared to laparoscopic sterilization. © 2014 Elsevier Inc.

Non-growing season CO2 emissions from Arctic tundra remain a major uncertainty in forecasting climate change consequences of permafrost thaw. We present the first time series of soil and microbial CO2 emissions from a graminoid tundra based on year-round in situ measurements of the radiocarbon content of soil CO2 (Δ14CO2) and of bulk soil C (Δ14C), microbial activity, and temperature. Combining these data with land-atmosphere CO2 exchange allows estimates of the proportion and mean age of microbial CO2 emissions year-round. We observe a seasonal shift in emission sources from fresh carbon during the growing season (August Δ14CO2 = 74 ± 4.7‰, 37% ± 3.4% microbial, mean ± se) to increasingly older soil carbon in fall and winter (March Δ14CO2 = 22 ± 1.3‰, 47% ± 8% microbial). Thus, rising soil temperatures and emissions during fall and winter are depleting aged soil carbon pools in the active layer and thawing permafrost and further accelerating climate change.

Fossil fuel carbon dioxide (CO2) emissions (ffCO2) constitute the majority of greenhouse gas emissions and are the main determinant of global climate change. The COVID-19 pandemic caused wide-scale disruption to human activity and provided an opportunity to evaluate our capability to detect ffCO2 emission reductions. Quantifying changes in ffCO2 levels is especially challenging in cities, where climate mitigation policies are being implemented but local emissions lead to spatially and temporally complex atmospheric mixing ratios. Here, we assess ffCO2 emission patterns associated with pandemic-induced changes to human activity using direct observations of on-road CO2 mole fractions in the Los Angeles (LA) urban area and analyses of the radiocarbon (14C) content of annual grasses collected by community scientists throughout California, USA. With COVID-19 mobility restrictions in place in 2020, we observed a significant reduction in ffCO2 levels across California, especially in urban centers. In LA, on-road CO2 enhancements were 60 ± 16% lower than the corresponding period of 2019 and rebounded to pre-pandemic levels by 2021. Plant 14C analysis indicated ffCO2 reductions of 5 ± 10 ppm in 2020 relative to pre-pandemic observations in LA. However, ffCO2 emission trajectories varied substantially by region and sector as COVID-related restrictions were relaxed. Further development of these techniques could aid efforts to monitor decarbonization in cities, especially in developing countries without established CO2 monitoring infrastructure.

The carbon (C) balance of permafrost regions is predicted to be extremely sensitive to climatic changes. Major uncertainties exist in the rate of permafrost thaw and associated C emissions (33-508 Pg C or 0.04-1.69 °C by 2100; refs,) and plant C uptake. In the High Arctic, semi-deserts retain unique soil-plant-permafrost interactions and heterogeneous soil C pools (>12 Pg C; ref.). Owing to its coastal proximity, marked changes are expected for High Arctic tundra. With declining summer sea-ice cover, these systems are simultaneously exposed to rising temperatures, increases in precipitation and permafrost degradation. Here we show, using measurements of tundra-atmosphere C fluxes and soil C sources (14C) at a long-term climate change experiment in northwest Greenland, that warming decreased the summer CO 2 sink strength of semi-deserts by up to 55%. In contrast, warming combined with wetting increased the CO2 sink strength by an order of magnitude. Further, wetting while relocating recently assimilated plant C into the deep soil decreased old C loss compared with the warming-only treatment. Consequently, the High Arctic has the potential to remain a strong C sink even as the rest of the permafrost region transitions to a net C source as a result of future global warming. © 2014 Macmillan Publishers Limited. All rights reserved.