High N2 Fixation in and Near the Gulf Stream Consistent with a Circulation Control on Diazotrophy

The stoichiometry of physical nutrient supply may provide a constraint on the spatial distribution and rate of marine nitrogen (N2) fixation. Yet agreement between the N2 fixation rates inferred from nutrient supply and those directly measured has been lacking. The relative transport of phosphate and nitrate across the Gulf Stream suggests that 3–6 Tg N year−1 must be fixed to maintain steady nutrient stoichiometry in the North Atlantic subtropical gyre. Here we show direct measurements of N2 fixation consistent with these estimates, suggesting elevated N2 fixation in and near the Gulf Stream. At some locations across the Gulf Stream, we measured diazotroph abundances and N2 fixation rates that are 1–3 orders of magnitude greater than previously measured in the central North Atlantic subtropical gyre. In combination, rate measurements and gene abundances suggest that biogeochemical budgets can be a robust predictive tool for N2 fixation hot spots in the global ocean

CLIMODE Subsurface Mooring Report : November 2005 - November 2007

Two years of temperature, salinity, current, and nutrient data were collected on four subsurface moorings as part of the 2 year field component of the CLIMODE experiment. The moorings were located in North Atlantic’s subtropical gyre, south-east of the Gulf Stream. Two moorings, the most heavily instrumented, were close to the Gulf Stream, in the region where cold air outbreaks force large air-sea fluxes and where Eighteen Degree Water outcrops. Two other moorings were located farther south and carried more limited instrumentation. The moorings were initially deployed in November of 2005, turned around in November of 2006 and finally recovered in November of 2007. During the first year, the moorings close to the Gulf Stream suffered considerable blow down, and some of the instruments failed. During the second year, the blow down was greatly reduced and most instruments collected a full year worth of data.Funding was provided by the Division of Ocean Sciences of the National Science Foundation under Grant No. OCE-0424536

Long-term fat redistribution in ARV-naïve HIV+ patients initiating a non-thymidine containing regimen in clinical practice

Lipodystrophy is still a matter of concern in HIV patients receiving ART. However, long-term fat change in patients taking non-thymidine regimens is not well known

The CLIMODE field campaign : observing the cycle of convection and restratification over the Gulf Stream

Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Bulletin of the American Meteorological Society 90 (2009): 1337-1350, doi:10.1175/2009BAMS2706.1.A major oceanographic field experiment is described, which is designed to observe, quantify, and understand the creation and dispersal of weakly stratified fluid known as “mode water” in the region of the Gulf Stream. Formed in the wintertime by convection driven by the most intense air–sea fluxes observed anywhere over the globe, the role of mode waters in the general circulation of the subtropical gyre and its biogeo-chemical cycles is also addressed. The experiment is known as the CLIVAR Mode Water Dynamic Experiment (CLIMODE). Here we review the scientific objectives of the experiment and present some preliminary results.Physical Oceanography program of NS

Darunavir/cobicistat/emtricitabine/tenofovir alafenamide versus dolutegravir /abacavir/lamivudine in antiretroviral-naïve adults (SYMTRI): a multicenter randomized open-label study (PReEC/RIS-57)

D/C/F/TAF is the reference for combination therapy based on protease inhibitors but has not been compared with regimens containing integrase inhibitors as initial ART. We could not demonstrate D/C/F/TAF noninferiority relative to DTG/ABC/3TC, although both regimens were similarly well tolerated. Background Darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) is the reference for combination therapy based on protease inhibitors due to its efficacy, tolerability, and convenience. Head-to-head randomized comparisons between D/C/F/TAF and combination therapy based on integrase inhibitors in antiretroviral-naive patients are lacking. Methods Adult (>18 years old) human immunodeficiency virus-infected antiretroviral-naive patients (HLA-B*5701 negative and hepatitis B virus negative), with viral load (VL) >= 500 c/mL, were centrally randomized to initiate D/C/F/TAF or dolutegravir/abacavir/lamivudine (DTG/3TC/ABC) after stratifying by VL and CD4 count. Clinical and analytical assessments were performed at weeks 0, 4, 12, 24, and 48. The primary endpoint was VL 100 000 copies/mL, and 13% had <200 CD4 cells/mu L. Median weight was 73 kg and median body mass index was 24 kg/m(2). At 48 weeks, 79% (D/C/F/TAF) versus 82% (DTG/3TC/ABC) had VL <50 c/mL (difference, -2.4%; 95% confidence interval [CI], -11.3 to 6.6). Eight percent versus four percent experienced virologic failure but no resistance-associated mutations emerged. Four percent versus six percent had drug discontinuation due to adverse events. In the per-protocol analysis, 94% versus 96% of patients had VL <50 c/mL (difference, -2%; 95% CI, -8.1 to 3.5). There were no differences in CD4 cell count or weight changes. Conclusions We could not demonstrate the noninferiority of D/C/F/TAF relative to DTG/ABC/3TC as initial antiretroviral therapy, although both regimens were similarly well tolerated

How much fat loss is needed for lipoatrophy to become clinically evident?

The objective of this study was to evaluate how much limb fat is needed to be lost for lipoatrophy to become clinically evident. Antiretroviral drug-naive patients from a randomized trial comparing stavudine or abacavir plus lamivudine and efavirenz, who had subjective assessment to detect clinically evident lipoatrophy (standardized questionnaire) and objective measurements of limb fat (dual X-ray absorptiometry) at baseline, 48 weeks, and 96 weeks were included. ROC curves were used to assess the sensitivity and specificity of several cut-off values of absolute and percent limb fat loss for diagnosing lipoatrophy. Of 54 patients included, 13 (24%) had subjective lipoatrophy at 96 weeks. After 96 weeks, median limb fat change was −2.3 kg (interquartile range: −5.2, +0.2) and 0.4 kg (interquartile range: −7.2, +3.4) in patients with and without lipoatrophy, respectively. Median percent limb fat change was −45.5% (interquartile range: −78.0, +3.7) and 5.5% (interquartile range: −62.8, +95.6), respectively. The cut-off values of absolute and percent limb fat loss showing the best sensitivity and specificity values were −1.5 kg (sensitivity, 77%; specificity, 76%) and −30% (sensitivity, 85%; specificity, 73%). At least 30% limb fat is needed to be lost in HIV-infected patients for lipoatrophy to become clinically evident

Impact of switching from lopinavir/ritonavir to atazanavir/ritonavir on body fat redistribution in virologically suppressed HIV-infected adults

Changes in body fat distribution in virologically suppressed HIV-infected patients switching from lopinavir/ritonavir (LPV/r) to atazanavir/ritonavir (ATV/r) were assessed. A prospective comparative study was conducted of 37 patients receiving LPV/r regimens switching to ATV/r with 46 patients continuing with LPV/r. Body composition was assessed with whole-body dual-energy x-ray absorptiometry (DXA). Abdominal CT scans were also performed in a subset of patients. Groups were comparable in baseline demographic, clinical, and anthropometric characteristics. After 12 months, peripheral fat did not change significantly, but an increase in trunk fat was observed only in the ATV/r group (0.87 kg, p = 0.021). The percentage of patients with an increase ≥20% in total fat was 37.8% and 15.2% in the ATV/r and LPV/r groups, respectively (p = 0.018). In the ATV/r group, the increase in trunk fat (9.4%) was significantly higher than in peripheral fat (3.7%) (p = 0.007), leading to a significant increase in fat mass ratio (3.76%, p = 0.028), whereas no significant differences were found among LPV/r patients. CT scans showed that abdominal fat increase corresponded to both visceral (28%, p = 0.008) and subcutaneous fat (42%, p = 0.008). These data suggest that switching from LPV/r to ATV/r is associated with increased trunk fat, both subcutaneous and visceral

Underwater Gliders at Memorial University: Summary of Deployments and Collected Data 2006 - 2020

Memorial University has over the past 15 years been involved in various ocean glider activities with deployments focused primarily on the Newfoundland Shelf and the Labrador Sea. For example, there are four deployments with glider data in the Labrador Sea. Partnerships with Fisheries and Oceans Canada and Ocean Gliders Canada have also resulted in deployments of Memorial's gliders in the Pacific. The data contain 14’663 mission kms, 620 deployment days and 25’108 individual glider profiles. L1 NETCDF files for every deployment archived on the Memorial University’s Glider Data server are made available publicly for scientific research. Deployments vary in duration and region. All files were processed with the SOCIB glider toolbox (Troupin et al., 2015), modified by Nicolai von Oppeln-Bronikowski, 2019 for MUN glider deployments

Biogeochemical cycling of dissolved zinc along the GEOTRACES South Atlantic transect GA10 at 40°S

The biogeochemical cycle of zinc (Zn) in the South Atlantic, at 40°S, was investigated as part of the UK GEOTRACES program. To date there is little understanding of the supply of Zn, an essential requirement for phytoplankton growth, to this highly productive region. Vertical Zn profiles displayed nutrient-like distributions with distinct gradients associated with the watermasses present. Surface Zn concentrations are among the lowest reported for theworld’s oceans (<50 pM). A strong Zn-Si linear relationshipwas observed (Zn (nM)= 0.065 Si (μM), r2=0.97, n = 460). Our results suggest that the use of a global Zn-Si relationship would lead to an underestimation of dissolved Zn in deeper waters of the South Atlantic. By utilizing Si* and a new tracer Zn* our data indicate that the preferential removal of Zn in the Southern Ocean prevented a direct return path for dissolved Zn to the surface waters of the South Atlantic at 40°S and potentially the thermocline waters of the South Atlantic subtropical gyre. The importance of Zn for phytoplankton growth was evaluated using the Zn-soluble reactive phosphorus (SRP) relationship. We hypothesize that the low Zn concentrations in the South Atlantic may select for phytoplankton cells with a lower Zn requirement. In addition, a much deeper kink at ~ 500m in the Zn:SRP ratio was observed compared to other oceanic regions