Changes in aerosol properties during spring-summer period in the Arctic troposphere

The change in aerosol properties during the transition from the more polluted spring to the clean summer in the Arctic troposphere was studied. A six-year data set of observations from Ny-Ålesund on Svalbard, covering the months April through June, serve as the basis for the characterisation of this time period. In addition four-day-back trajectories were used to describe air mass histories. The observed transition in aerosol properties from an accumulation-mode dominated distribution to an Aitken-mode dominated distribution is discussed with respect to long-range transport and influences from natural and anthropogenic sources of aerosols and pertinent trace gases. Our study shows that the air-mass transport is an important factor modulating the physical and chemical properties observed. However, the air-mass transport cannot alone explain the annually repeated systematic and rather rapid change in aerosol properties, occurring within a limited time window of approximately 10 days. With a simplified phenomenological model, which delivers the nucleation potential for new-particle formation, we suggest that the rapid shift in aerosol microphysical properties between the Arctic spring and summer is mainly driven by the incoming solar radiation in concert with transport of precursor gases and changes in condensational sink

Constraints on oceanic methane emissions west of Svalbard from atmospheric in situ measurements and Lagrangian transport modeling

Methane stored in seabed reservoirs such as methane hydrates can reach the atmosphere in the form of bubbles or dissolved in water. Hydrates could destabilize with rising temperature further increasing greenhouse gas emissions in a warming climate. To assess the impact of oceanic emissions from the area west of Svalbard, where methane hydrates are abundant, we used measurements collected with a research aircraft (Facility for Airborne Atmospheric Measurements) and a ship (Helmer Hansen) during the Summer 2014 and for Zeppelin Observatory for the full year. We present a model-supported analysis of the atmospheric CH$_{4}$mixing ratios measured by the different platforms. To address uncertainty about where CH$_{4}$ emissions actually occur, we explored three scenarios: areas with known seeps, a hydrate stability model, and an ocean depth criterion. We then used a budget analysis and a Lagrangian particle dispersion model to compare measurements taken upwind and downwind of the potential CH$_{4}$ emission areas. We found small differences between the CH$_{4}$ mixing ratios measured upwind and downwind of the potential emission areas during the campaign. By taking into account measurement and sampling uncertainties and by determining the sensitivity of the measured mixing ratios to potential oceanic emissions, we provide upper limits for the CH$_{4}$ fluxes. The CH$_{4}$ flux during the campaign was small, with an upper limit of 2.5 nmol m$^{-2}$ s$^{-1}$ in the stability model scenario. The Zeppelin Observatory data for 2014 suggest CH$_{4}$ fluxes from the Svalbard continental platform below 0.2 Tg yr$^{-1}$. All estimates are in the lower range of values previously reported.MOCA—Methane Emissions from the Arctic OCean to the Atmosphere: Present and Future Climate Effects is funded by the Research Council of Norway, grant 225814. CAGE—Centre for Arctic Gas Hydrate, Environment and Climate research work was supported by the Research Council of Norway through its Centres of Excellence funding scheme grant 223259. eSTICC—eScience Tools for Investigating Climate Change in northern high latitudes is supported by Nordforsk as Nordic Center of Excellence grant 57001. NERC grants NE/I029293/1 (PI. H. Coe) and NE/I02916/1 (PI J. Pyle) and Methane & Other Greenhouse Gases in the Arctic—Measurements, Process Studies and Modelling (MAMM). The ERC through the ACCI project, project number 267760. The biogenic methane emission data from the LPX-Bern v1.2 model were provided by Renato Spahni. The methane emission data from the GAINS model were provided by IIASA. GFED data are available from http://www.globalfiredata.org/index.html. Airborne data were obtained using the BAe-146-301 Atmospheric Research Aircraft (ARA) flown by Directflight Ltd. and managed by the Facility for Airborne Atmospheric Measurements (FAAM), which is a joint entity of the Natural Environment Research Council (NERC) and the Met Office. Zeppelin and Helmer Hansen atmospheric measurement data are archived in EBAS (http://ebas.nilu.no/) for long-term preservation, access and use. All Zeppelin data for 2014: http://ebas.nilu.no/DataSets.aspx?stations=NO0042G&fromDate=2014-01-01&toDate=2014-12-31. All atmospheric data from RV Helmer Hanssen: http://ebas.nilu.no/DataSets.aspx?stations=NO1000R&fromDate=2014-01-01&toDate=2014-12-31 (password is required until the end of 2017)

Atmospheric constraints on the methane emissions from the East Siberian Shelf

Subsea permafrost and hydrates in the East Siberian Arctic Shelf (ESAS) constitute a substantial carbon pool, and a potentially large source of methane to the atmosphere. Previous studies based on interpolated oceanographic campaigns estimated atmospheric emissions from this area at 8–17 TgCH₄ yr⁻¹. Here, we propose insights based on atmospheric observations to evaluate these estimates. The comparison of high-resolution simulations of atmospheric methane mole fractions to continuous methane observations during the whole year 2012 confirms the high variability and heterogeneity of the methane releases from ESAS. A reference scenario with ESAS emissions of 8 TgCH₄ yr⁻¹, in the lower part of previously estimated emissions, is found to largely overestimate atmospheric observations in winter, likely related to overestimated methane leakage through sea ice. In contrast, in summer, simulations are more consistent with observations. Based on a comprehensive statistical analysis of the observations and of the simulations, annual methane emissions from ESAS are estimated to range from 0.0 to 4.5 TgCH₄ yr⁻¹. Isotopic observations suggest a biogenic origin (either terrestrial or marine) of the methane in air masses originating from ESAS during late summer 2008 and 2009

Probability of Achieving Glycemic Control with Basal Insulin in Patients with Type 2 Diabetes in Real-World Practice in the USA

Introduction: Basal insulin (BI) plays an important role in treating type 2 diabetes (T2D), especially when oral antidiabetic (OAD) medications are insufficient for glycemic control. We conducted a retrospective, observational study using electronic medical records (EMR) data from the IBM ® Explorys database to evaluate the probability of achieving glycemic control over 24 months after BI initiation in patients with T2D in the USA. Methods: A cohort of 6597 patients with T2D who started BI following OAD(s) and had at least one valid glycated hemoglobin (HbA1c) result recorded both within 90 days before and 720 days after BI initiation were selected. We estimated the changes from baseline in HbA1c every 6 months, the quarterly conditional probabilities of reaching HbA1c &lt; 7% if a patient had not achieved glycemic control prior to each quarter (Q), and the cumulative probability of reaching glycemic control over 24 months. Results: Our cohort was representative of patients with T2D who initiated BI from OADs in the USA. The average HbA1c was 9.1% at BI initiation, and decreased robustly (1.5%) in the first 6 months after initiation with no further reductions thereafter. The conditional probability of reaching glycemic control decreased rapidly in the first year (26.6% in Q2; 17.6% in Q3; 8.6% in Q4), and then remained low (≤ 6.1%) for each quarter in the second year. Cumulatively, about 38% of patients reached HbA1c &lt; 7% in the first year; only approximately 8% more did so in the second year. Conclusion: Our study of real-world data from a large US EMR database suggested that among patients with T2D who initiated BI after OADs, the likelihood of reaching glycemic control diminished over time, and remained low from 12 months onwards. Additional treatment options should be considered if patients do not reach glycemic control within 12 months of BI initiation. Funding: Sanofi Corporation. </p

History of chemically and radiatively important atmospheric gases from the Advanced Global Atmospheric Gases Experiment (AGAGE)

We present the organization, instrumentation, datasets, data interpretation, modeling, and accomplishments of the multinational global atmospheric measurement program AGAGE (Advanced Global Atmospheric Gases Experiment). AGAGE is distinguished by its capability to measure globally, at high frequency, and at multiple sites all the important species in the Montreal Protocol and all the important non-carbon-dioxide (non-CO₂) gases assessed by the Intergovernmental Panel on Climate Change (CO₂ is also measured at several sites). The scientific objectives of AGAGE are important in furthering our understanding of global chemical and climatic phenomena. They are the following: (1) to accurately measure the temporal and spatial distributions of anthropogenic gases that contribute the majority of reactive halogen to the stratosphere and/or are strong infrared absorbers (chlorocarbons, chlorofluorocarbons – CFCs, bromocarbons, hydrochlorofluorocarbons – HCFCs, hydrofluorocarbons – HFCs and polyfluorinated compounds (perfluorocarbons – PFCs), nitrogen trifluoride – NF₃, sulfuryl fluoride – SO₂F₂, and sulfur hexafluoride – SF₆) and use these measurements to determine the global rates of their emission and/or destruction (i.e., lifetimes); (2) to accurately measure the global distributions and temporal behaviors and determine the sources and sinks of non-CO₂ biogenic–anthropogenic gases important to climate change and/or ozone depletion (methane – CH₄, nitrous oxide – N₂O, carbon monoxide – CO, molecular hydrogen – H₂, methyl chloride – CH₃Cl, and methyl bromide – CH₃Br); (3) to identify new long-lived greenhouse and ozone-depleting gases (e.g., SO₂F₂, NF₃, heavy PFCs (C₄F₁₀, C₅F₁₂, C₆F₁₄, C₇F₁₆, and C₈F₁₈) and hydrofluoroolefins (HFOs; e.g., CH₂  =  CFCF₃) have been identified in AGAGE), initiate the real-time monitoring of these new gases, and reconstruct their past histories from AGAGE, air archive, and firn air measurements; (4) to determine the average concentrations and trends of tropospheric hydroxyl radicals (OH) from the rates of destruction of atmospheric trichloroethane (CH₃CCl₃), HFCs, and HCFCs and estimates of their emissions; (5) to determine from atmospheric observations and estimates of their destruction rates the magnitudes and distributions by region of surface sources and sinks of all measured gases; (6) to provide accurate data on the global accumulation of many of these trace gases that are used to test the synoptic-, regional-, and global-scale circulations predicted by three-dimensional models; and (7) to provide global and regional measurements of methane, carbon monoxide, and molecular hydrogen and estimates of hydroxyl levels to test primary atmospheric oxidation pathways at midlatitudes and the tropics. Network Information and Data Repository: <a href="http://agage.mit.edu/data" target="_blank">http://agage.mit.edu/data</a> or <a href="http://cdiac.ess-dive.lbl.gov/ndps/alegage.html" target="_blank">http://cdiac.ess-dive.lbl.gov/ndps/alegage.html</a> (<a href="https://doi.org/10.3334/CDIAC/atg.db1001" target="_blank">https://doi.org/10.3334/CDIAC/atg.db1001</a>)

Influence of training status on high-intensity intermittent performance in response to β-alanine supplementation

Recent investigations have suggested that highly trained athletes may be less responsive to the ergogenic effects of β-alanine (BA) supplementation than recreationally active individuals due to their elevated muscle buffering capacity. We investigated whether training status influences the effect of BA on repeated Wingate performance. Forty young males were divided into two groups according to their training status (trained: T, and non-trained: NT cyclists) and were randomly allocated to BA and a dextrose-based placebo (PL) groups, providing four experimental conditions: NTPL, NTBA, TPL, TBA. BA (6.4 g day-1 ) or PL was ingested for 4 weeks, with participants completing four 30-s lower-body Wingate bouts, separated by 3 min, before and after supplementation. Total work done was significantly increased following supplementation in both NTBA (p = 0.03) and TBA (p = 0.002), and it was significantly reduced in NTPL (p = 0.03) with no difference for TPL (p = 0.73). BA supplementation increased mean power output (MPO) in bout 4 for the NTBA group (p = 0.0004) and in bouts 1, 2 and 4 for the TBA group (p ≤ 0.05). No differences were observed in MPO for NTPL and TPL. BA supplementation was effective at improving repeated high-intensity cycling performance in both trained and non-trained individuals, highlighting the efficacy of BA as an ergogenic aid for high-intensity exercise regardless of the training status of the individual

Glycemic control and long-acting insulin analog utilization in patients with type 2 diabetes

Introduction: The objective was to compare glycemic control, insulin utilization, and body weight in patients with type 2 diabetes (T2D) initiated on insulin detemir (IDet) or insulin glargine (IGlar) in a real-life setting in the Netherlands. Methods: Insulin-naïve patients with T2D, starting treatment with IDet or IGlar between January 1, 2004 and June 30, 2008, were selected from the PHARMO data network. Glycemic control (hemoglobin A1c [HbA1c]), target rates (HbA1c <7%), daily insulin dose, and weight gain were analyzed comparing IDet and IGlar for patients with available HbA1c levels both at baseline and at 1-year follow-up. Analysis of all eligible patients (AEP) and a subgroup of patients without treatment changes (WOTC) in the follow-up period were adjusted for patient characteristics, propensity scores, and baseline HbA1c. Results: A total of 127 IDet users and 292 IGlar users were included in the WOTC analyses. The mean HbA1c dropped from 8.4%-8.6% at baseline to 7.4% after 1 year. Patients at HbA1c goal increased from 9% at baseline to 32% for IDet and 11% to 35% for IGlar, which was not significantly different (OR 0.75, 95% CI 0.46, 1.24). Weight gain (n=90) was less among IDet users (+0.4kg) than among IGlar users (+1.1kg), albeit not significant. The AEP analysis (252 IDet

Effects of Insulin Detemir and NPH Insulin on Body Weight and Appetite-Regulating Brain Regions in Human Type 1 Diabetes: A Randomized Controlled Trial

Studies in rodents have demonstrated that insulin in the central nervous system induces satiety. In humans, these effects are less well established. Insulin detemir is a basal insulin analog that causes less weight gain than other basal insulin formulations, including the current standard intermediate-long acting Neutral Protamine Hagedorn (NPH) insulin. Due to its structural modifications, which render the molecule more lipophilic, it was proposed that insulin detemir enters the brain more readily than other insulins. The aim of this study was to investigate whether insulin detemir treatment differentially modifies brain activation in response to food stimuli as compared to NPH insulin. In addition, cerebral spinal fluid (CSF) insulin levels were measured after both treatments. Brain responses to viewing food and non-food pictures were measured using functional Magnetic Resonance Imaging in 32 type 1 diabetic patients, after each of two 12-week treatment periods with insulin detemir and NPH insulin, respectively, both combined with prandial insulin aspart. CSF insulin levels were determined in a subgroup. Insulin detemir decreased body weight by 0.8 kg and NPH insulin increased weight by 0.5 kg (p = 0.02 for difference), while both treatments resulted in similar glycemic control. After treatment with insulin detemir, as compared to NPH insulin, brain activation was significantly lower in bilateral insula in response to visual food stimuli, compared to NPH (p = 0.02 for right and p = 0.05 for left insula). Also, CSF insulin levels were higher compared to those with NPH insulin treatment (p = 0.003). Our findings support the hypothesis that in type 1 diabetic patients, the weight sparing effect of insulin detemir may be mediated by its enhanced action on the central nervous system, resulting in blunted activation in bilateral insula, an appetite-regulating brain region, in response to food stimuli.ClinicalTrials.gov NCT00626080

Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere

© 2016. American Geophysical Union. All Rights Reserved. We find that summer methane (CH4) release from seabed sediments west of Svalbard substantially increases CH4 concentrations in the ocean but has limited influence on the atmospheric CH4 levels. Our conclusion stems from complementary measurements at the seafloor, in the ocean, and in the atmosphere from land-based, ship and aircraft platforms during a summer campaign in 2014. We detected high concentrations of dissolved CH4 in the ocean above the seafloor with a sharp decrease above the pycnocline. Model approaches taking potential CH4 emissions from both dissolved and bubble-released CH4 from a larger region into account reveal a maximum flux compatible with the observed atmospheric CH4 mixing ratios of 2.4-3.8 nmol m-2 s-1. This is too low to have an impact on the atmospheric summer CH4 budget in the year 2014. Long-term ocean observatories may shed light on the complex variations of Arctic CH4 cycles throughout the year.The project MOCA- Methane Emissions from the Arctic OCean to the Atmosphere: Present and Future Climate Effects is funded by the Research Council of Norway, grant no.225814 CAGE – Centre for Arctic Gas Hydrate, Environment and Climate research work was supported by the Research Council of Norway through its Centres of Excellence funding scheme grant no. 223259. Nordic Center of Excellence eSTICC (eScience Tool for Investigating Climate Change in northern high latitudes) funded by Nordforsk, grant no. 57001