Atlantic Water Modification North of Svalbard in the Mercator Physical System From 2007 to 2020

The Atlantic Water (AW) inflow through Fram Strait, largest oceanic heat source to the Arctic Ocean, undergoes substantial modifications in the Western Nansen Basin (WNB). Evaluation of the Mercator system in the WNB, using 1,500 independent temperature‐salinity profiles and five years of mooring data, highlighted its performance in representing realistic AW inflow and hydrographic properties. In particular, favorable comparisons with mooring time‐series documenting deep winter mixed layers and changes in AW properties led us to examine winter conditions in the WNB over the 2007–2020 period. The model helped describe the interannual variations of winter mixed layers and documented several processes at stake in modifying AW beyond winter convection: trough outflows and lateral exchange through vigorous eddies. Recently modified AW, either via local convection or trough outflows, were identified as homogeneous layers of low buoyancy frequency. Over the 2007–2020 period, two winters stood out with extreme deep mixed layers in areas that used to be ice‐covered: 2017/18 over the northern Yermak Plateau‐Sofia Deep; 2012/13 on the continental slope northeast of Svalbard with the coldest and freshest modified AW of the 12‐year time series. The northern Yermak Plateau‐Sofia Deep and continental slope areas became “Marginal Convection Zones” in 2011 with, from then on, occasionally ice‐free conditions, 50‐m‐ocean temperatures always above 0 °C and highly variable mixed layer depths and ocean‐to‐atmosphere heat fluxes. In the WNB where observations require considerable efforts and resources, the Mercator system proved to be a good tool to assess Atlantic Water modifications in winter

Changes in Atlantic Water circulation patterns and volume transports North of Svalbard over the last 12 years (2008-2020)

Atlantic Water (AW) enters the Arctic through Fram Strait as the West Spitsbergen Current (WSC). When reaching the south of Yermak Plateau, the WSC splits into the Svalbard, Yermak Pass and Yermak Branches. Downstream of Yermak Plateau, AW pathways remain unclear and uncertainties persist on how AW branches eventually merge and contribute to the boundary current along the continental slope. We took advantage of the good performance of the 1/12° Mercator Ocean model in the Western Nansen Basin (WNB) to examine the AW circulation and volume transports in the area. The model showed that the circulation changed in 2008-2020. The Yermak Branch strengthened over the northern Yermak Plateau, feeding the Return Yermak Branch along the eastern flank of the Plateau. West of Yermak Plateau, the Transpolar Drift likely shifted westward while AW recirculations progressed further north. Downstream of the Yermak Plateau, an offshore current developed above the 3800 m isobath, fed by waters from the Yermak Plateau tip. East of 18°E, enhanced mesoscale activity from the boundary current injected additional AW basin-ward, further contributing to the offshore circulation. A recurrent anticyclonic circulation in Sofia Deep developed, which also occasionally fed the western part of the offshore flow. The intensification of the circulation coincided with an overall warming in the upper WNB (0-1000 m), consistent with the progression of AW. This regional description of the changing circulation provides a background for the interpretation of upcoming observations

Changes in Arctic Halocline Waters along the East Siberian Slope and in the Makarov Basin from 2007 to 2020

The Makarov Basin halocline receives contributions from diverse water masses of Atlantic, Pacific, and East Siberian Sea origin. Changes in surface circulation (e.g., in the Transpolar Drift and Beaufort Gyre) have been documented since the 2000s, while the upper ocean column in the Makarov Basin has received little attention. The evolution of the upper and lower halocline in the Makarov Basin and along the East Siberian Sea slope was examined combining drifting platforms observations, shipborne hydrographic data, and modelled fields from a global operational physical model. In 2015, the upper halocline in the Makarov Basin was warmer, fresher, and thicker compared to 2008 and 2017, likely resulting from the particularly westward extension of the Beaufort Gyre that year. From 2012-onwards, cold Atlantic-derived lower halocline waters, previously restricted to the Lomonosov Ridge area, progressed eastward along the East Siberian slope, with a sharp shift from 155 to 170°E above the 1000 m isobath in winter 2011-2012, followed by a progressive eastward motion after winter 2015-2016 and reached the western Chukchi Sea in 2017. In parallel, an active mixing between upwelled Atlantic water and shelf water along the slope, formed dense warm water which also supplied the Makarov Basin lower halocline. The progressive weakening of the halocline, together with shallower Atlantic Waters, is emblematic of a new Arctic Ocean regime that started in the early 2000s in the Eurasian Basin. Our results suggest that this new Arctic regime now may extend toward the Amerasian Basin

A Randomized Comparison of High Clopidogrel Loading Doses in Patients With Non–ST-Segment Elevation Acute Coronary Syndromes The ALBION (Assessment of the Best Loading Dose of Clopidogrel to Blunt Platelet Activation, Inflammation and Ongoing Necrosis) Trial

ObjectivesWe sought to compare the antiplatelet effects of three clopidogrel loading doses (LDs).BackgroundAdministration of a 300-mg clopidogrel LD is beneficial in situations requiring rapid platelet inhibition. Whether higher LDs can provide further benefits remains unknown.MethodsPatients (n = 103) with non–ST-segment elevation acute coronary syndromes were randomized to receive a 300-mg, 600-mg, or 900-mg clopidogrel LD, given on top of other standard therapy (including acetylsalicylic acid). The main outcome measure was inhibition of adenosine diphosphate-induced inhibition of platelet aggregation (IPA); inhibition of platelet activation, inflammatory markers, troponin I release, and major adverse cardiac events also were evaluated; all measures were blindly evaluated.ResultsCompared with the 300-mg LD, greater doses were associated with significantly greater platelet inhibition, with dose-effect relationships observed for onset of action, maximal plateau, 24-h areas under the curves of IPA, and rates of low IPA (<10% at 6 h), using 20 μmol/l major adverse cardiac events. A significant dose-response was also observed for the vasodilator-stimulated phosphoprotein index, a measure of P2Y12receptor inhibition. Similar but nonsignificant trends were observed for troponin release and major adverse cardiac events. Bleeding rates were similar in each group.ConclusionsIn low-to-moderate risk patients with non–ST-elevation acute coronary syndromes, clopidogrel LDs >300 mg provide a faster onset of action, a higher IPA plateau, and greater reductions in platelet activation during the first 24 h. A 900-mg LD may induce a greater antiplatelet effect than 600 mg, when compared with the standard 300-mg regimen. These findings require further clinical confirmation

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

From basin to subbasin scale assessment and intercomparison of numerical simulations in the Western Mediterranean Sea

© 2015 Elsevier B.V. This study describes a quantitative evaluation of simulations in the western Mediterranean Sea at basin and subbasin scales. The Mediterranean Forecasting System and the MercatorOcéan simulations provide operational ocean forecasts and hindcasts in the Mediterranean, and are also used as initial and boundary conditions for regional models. In this context, hindcast simulations from 2009 to 2012 are compared with available multiplatform observations at various spatial and temporal scales to evaluate their performance. Both simulations reproduce well the observed mean conditions and variability over the last years. The subbasin scale analyses of the threedimensional ocean structures and water mass properties reveal seasonal and regional temperature and salinity errors at the surface in both simulations, as well as significant biases at intermediate and deep layers in the Mediterranean Forecasting System. The simulated surface geostrophic velocities are weaker than those derived from altimetry, and circulation biases persist in the Balearic Sea. Additionally, the seasonal existence of the Alboran gyres is not well reproduced in either simulation. The identification of regional simulation biases is essential to advance from global to regional and local scale forecasting, in particular, improving the representation of the local physical processes and their interactions with the subbasin dynamics and the general circulationPartial support from JERICO, GROOM EU and MyOcean funded projects for the deployment of gliders in the Ibiza Channel is acknowledged as well as the IMEDEA and SOCIB techniciansPeer reviewe

Assessing the impact of SAR altimetry for global ocean analysis and forecasting

Satellite altimetry provides essential sea level observations to constrain ocean analysis and forecasting systems. New generation of nadir altimeters now provides enhanced capability thanks to a SAR mode that allows reducing the 1 Hz (7 km) measurement noise level from about 3 to 1 cm RMS. A first assessment of the impact of SAR altimetry for global ocean analysis and forecasting is carried out using Observing System Simulation Experiments (OSSEs) with the global Mercator Ocean high resolution 1/12° system. OSSEs are used to quantify the impact of assimilating multiple altimeter missions with and without a SAR mode. A simple twin experiment set up that only takes into account initialisation errors and impact of altimeter random noise is used. Results are analysed in high eddy energy regions where initialisation errors are the most important ones. Both sea surface height and surface velocity analyses and 7-day forecasts are improved. Compared to conventional altimetry, SAR altimetry sea surface height variance errors for both analyses and forecasts are typically reduced by 20% in western boundary currents. This suggests that use of SAR multiple altimeter missions with high-resolution models will significantly improve the capability of the ocean analysis and forecasting systems in the near future

Impact of functional inorganic nanotubes f-INTs-WS on hemolysis, platelet function and coagulation.

Inorganic transition metal dichalcogenide nanostructures are interesting for several biomedical applications such as coating for medical devices (e.g. endodontic files, catheter stents) and reinforcement of scaffolds for tissue engineering. However, their impact on human blood is unknown. A unique nanomaterial surface-engineering chemical methodology was used to fabricate functional polyacidic polyCOOH inorganic nanotubes of tungsten disulfide towards covalent binding of any desired molecule/organic species via chemical activation/reactivity of this former polyCOOH shell. The impact of these nanotubes on hemolysis, platelet aggregation and blood coagulation has been assessed using spectrophotometric measurement, light transmission aggregometry and thrombin generation assays. The functionalized nanotubes do not induce hemolysis but decrease platelet aggregation and induce coagulation through intrinsic pathway activation. The functional nanotubes were found to be more thrombogenic than the non-functional ones, suggesting lower hemocompatibility and increased thrombotic risk with functionalized tungsten disulfide nanotubes. These functionalized nanotubes should be used with caution in blood-contacting devices

Revisiting the Malvinas Current upper circulation and water masses using a highresolution ocean reanalysis

International audienceWe use 25 years of a high-resolution ocean reanalysis (1/12°) to revisit the Malvinas Current (MC) from the South (Drake Passage) to the North (Brazil-Malvinas Confluence) from the synoptic to interannual time scales. The Malvinas Plateau is home to active eddy mixing, eddy dissipation and deep winter mixed layers occasionally reaching 600 m depth. The MC is organized in two jets which merge around 44°S as the continental slope steepens. The upper 900 m transport mean decreases from 40 Sv at 51°S to 35 Sv at 41°S indicating offshore leakage along the MC path. The MC plays a minor role in the velocity variations observed at the Confluence at seasonal and interannual scales; those are driven by changes in the intensity of the Brazil Current over the slope (34–36°S). Computing MC transport time series at different latitudes requires care because the section eastern limits are embedded in an energetic region. Transport time series were produced at selected latitudes using different criteria and showed common features. They show little seasonality (relative seasonal standard deviation of 2%) and no significant trend. The MC is a steady current: the relative standard deviation is on the order of 10% increasing to 20% near and on the Malvinas Plateau and near the Confluence. In contrast, velocity trends are large in the Brazil Current with the overshoot migrating southward. The associated increase in mesoscale activity south of 44°S in the Argentine Basin might contribute to blocking events occasionally reducing the MC transport

The Malvinas Current at the Confluence With the Brazil Current: Inferences From 25 Years of Mercator Ocean reanalysis

Twenty‐five years of high‐resolution (1/12°) ocean reanalysis are used to examine the Confluence of the Malvinas Current (MC) with the Brazil Current (BC) from synoptic to interannual time scales. The model transports of the MC (38.0 Sv ± 7.4 Sv 57 at 41°S) and the BC (23.0 Sv ± 11 Sv at 36°S) agree with observations. The model shows the branching of the MC near the Confluence with an offshore branch returning south and an inner branch sinking below the BC and managing to continue northward along the continental slope. Northward velocities associated with the subsurface inner branch peak at 40 cm/s at 36°S at 700‐m depth. The model documents the migrations of the Subantarctic (SAF) and Subtropical Fronts (STF) at the Confluence. The SAF and STF positions vary over a large range at synoptic (800 km) and interannual scale (300 and 200 km, respectively) compared to the rather small seasonal migrations of the STF (150 km) and SAF (50 km). While trends in the MC are small over the 25 years of the reanalysis, the BC becomes more intense (12.5 cm/s), saltier (0.37 psu), and warmer (2.5°C) in the upper 1,000 m. These trends are accompanied with a southward displacement of the STF and the SAF of 150 and 50 km