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  1. Article ; Online: Diapycnal mixing in the Brazil-Malvinas confluence front

    Roget, Elena / Pelegrí, Josep L. / Planella-Morato, Jesús / Puigdefàbregas, Joan / Emelianov, Mikhail / Vallès-Casanova, Ignasi / Orúe-Echevarria, Dorleta

    Progress in Oceanography. 2023 Feb., v. 211 p.102968-

    2023  

    Abstract: Diapycnal mixing in the Brazil-Malvinas Confluence Zone (BMC) is assessed on the basis of microstructure measurements done as part of an April 2017 cruise, which explored the mesoscalar and regional frontal dynamics. Sampling was done down to 400 m in 11 ...

    Abstract Diapycnal mixing in the Brazil-Malvinas Confluence Zone (BMC) is assessed on the basis of microstructure measurements done as part of an April 2017 cruise, which explored the mesoscalar and regional frontal dynamics. Sampling was done down to 400 m in 11 locations on both sides of the BMC, over the slope and in the abyssal waters. Turbulent scales, non-dimensional numbers, energy dissipation rates and diapycnal eddy diffusivities are calculated, which allow us to assess the state of the small-scale turbulence in the frontal region. Active turbulence was present at all depths and stations, with high-dissipation patches ranging from several metres to a few tens of metres. The frontal zone is characterized by high energy dissipation and eddy diffusivity. The geometric mean eddy diffusivity for all stations and the entire water column is 7.0 × 10⁻⁴ m² s⁻¹. The mean values halve when only considering the more stratified seasonal thermocline, 3.8 × 10⁻⁴ m² s⁻¹, and are twice larger south than north of the BMC. High dissipation rates coincide with high vertical shear, possibly related to the convergence of the two intense currents and/or the generation of internal waves by the associated mesoscalar and submesoscalar features. The layered structures related to intruding filaments favor double diffusive convection and salt fingering. Near-bottom mixing at the stations on the continental slope is possible related to shear-driven Kelvin-Helmoltz instabilities.
    Keywords convection ; diffusivity ; energy ; microstructure ; oceanography ; turbulent flow
    Language English
    Dates of publication 2023-02
    Publishing place Elsevier Ltd
    Document type Article ; Online
    Note Use and reproduction
    ISSN 0079-6611
    DOI 10.1016/j.pocean.2023.102968
    Database NAL-Catalogue (AGRICOLA)

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  2. Article: The Transfer of Antarctic Circumpolar Waters to the Western South Atlantic Ocean

    Olivé Abelló, Anna / Pelegrí, Josep L. / Machín, Francisco J. / Vallès‐Casanova, Ignasi

    Journal of geophysical research. 2021 July, v. 126, no. 7

    2021  

    Abstract: Southern Ocean waters enter the South Atlantic Ocean through the Scotia Sea along pathways constrained by the bathymetry of the northern Scotia Sea passages. We use the Argo profiling‐float data set to calculate the water transports in and out of the ... ...

    Abstract Southern Ocean waters enter the South Atlantic Ocean through the Scotia Sea along pathways constrained by the bathymetry of the northern Scotia Sea passages. We use the Argo profiling‐float data set to calculate the water transports in and out of the region, focusing on the water balances down to the deepest isoneutral sampled in all passages (γⁿ = 28.0 kg m⁻³, located between about 500 and 2,000 m in the Drake Passage and even shallower in the Northern Passages). Down to this reference level, the water inflow through the Drake Passage is 140.8 ± 7.4 Sv and the water outflow through the deeper portions of the Northern Passages is 115.9 ± 8.3 Sv, implying a leakage of about 25 ± 11.1 Sv over topography shallower than 1,000 m. Below the reference isoneutral and down to 2,000 m, an additional 23.4 Sv enter through the Drake Passage; when added to reported inputs of about 20 Sv through the South Scotia Ridge, this accounts well for the observed 43.4 Sv outflow–from 28.0 kg m⁻³ to 2,000 m–through the Northern Passages. Relative to the 2,000 m reference level, the mean barotropic contribution always represents over half the total transports. We also observe substantial seasonal and moderate interannual variations in the water transports and composition (peak differences occur seasonally in the Drake Passage, with a range of 111–174 Sv), associated with changes in water exchange across the frontal systems. Two independent measures set the water mean‐residence time in the Scotia Sea at about 6–8 months.
    Keywords data collection ; geophysics ; research ; topography ; Antarctic region ; Atlantic Ocean
    Language English
    Dates of publication 2021-07
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 161667-5
    ISSN 2169-9291 ; 2169-9275 ; 0148-0227 ; 0196-2256
    ISSN (online) 2169-9291
    ISSN 2169-9275 ; 0148-0227 ; 0196-2256
    DOI 10.1029/2020JC017025
    Database NAL-Catalogue (AGRICOLA)

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  3. Article: Water Mass Transports and Pathways in the North Brazil‐Equatorial Undercurrent Retroflection

    Vallès‐Casanova, Ignasi / Fraile‐Nuez, Eugenio / Martín‐Rey, Marta / van Sebille, Erik / Cabré, Anna / Olivé‐Abelló, Anna / Pelegrí, Josep L.

    Journal of geophysical research. 2022 May, v. 127, no. 5

    2022  

    Abstract: The equatorial retroflection of the North Brazil Current (NBC) into the Equatorial Undercurrent (EUC) and its posterior tropical recirculation is a major regulator for the returning limb of the Atlantic Meridional Overturning Circulation. Indeed, most ... ...

    Abstract The equatorial retroflection of the North Brazil Current (NBC) into the Equatorial Undercurrent (EUC) and its posterior tropical recirculation is a major regulator for the returning limb of the Atlantic Meridional Overturning Circulation. Indeed, most surface and thermocline NBC waters retroflect at the equator all the way into the central and eastern Atlantic Ocean, before they recirculate back through the tropics to the western boundary. Here, we use cruise data in the western equatorial Atlantic during April 2010 and reanalysis time series for the equatorial and tropical waters in both hemispheres in order to explore the recirculation pathways and transport variability. During the 1998–2016 period, the annual‐mean EUC transports 15.1 ± 1.3 Sv at 32°W, with 2.8 ± 0.4 Sv from the North Atlantic and 11.4 ± 1.3 Sv from the South Atlantic. At 32°W most of the total EUC transport comes from the western boundary retroflection south of 3°N (7.2 ± 0.9 Sv), a substantial fraction retroflects north of 3°N (5.6 ± 0.4 Sv), and the remaining flow (2.3 Sv) joins through the interior basin. The South Atlantic subtropical waters feed the EUC at all thermocline depths while the North Atlantic and South Atlantic tropical waters do so at the surface and upper‐thermocline levels. The EUC transport at 32°W has a pronounced seasonality, with spring and fall maxima and a range of 8.8 Sv. The 18 yr of reanalysis data shows a weak yet significant correlation with an Atlantic Niño index, and also suggests an enhanced contribution from the South Atlantic tropical waters during 2008–2016 as compared with 1997–2007.
    Keywords basins ; geophysics ; research ; spring ; time series analysis ; Atlantic Ocean ; Brazil
    Language English
    Dates of publication 2022-05
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 161667-5
    ISSN 2169-9291 ; 2169-9275 ; 0148-0227 ; 0196-2256
    ISSN (online) 2169-9291
    ISSN 2169-9275 ; 0148-0227 ; 0196-2256
    DOI 10.1029/2021JC018150
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

    Z 2004/712: Show issues
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  4. Article ; Online: Retention in care among people living with HIV in the national antiretroviral therapy programme in Guinea: A retrospective cohort analysis.

    Kadio, Kadio Jean-Jacques Olivier / Cissé, Amadou / Diallo, Thierno Saidou / Guilavogui, Foromo / Tounkara, Adrien Fapeingou / Pe, Damey / Sow, Alhassane / Bah, Fatoumata Fily / Youla, Souleymane Sékou / Diallo, Ibrahima / Leno, Niouma Nestor / Mboungou, Lazare / Ahiatsi, Nyawotope Koffi Arnold / Kaba, Laye / Zeynabou, Sy / Vallès-Casanova, Ignasi / Wringe, Alison / Hoibak, Sarah / Koïta, Youssouf /
    Vallès, Xavier

    PLOS global public health

    2023  Volume 3, Issue 5, Page(s) e0000970

    Abstract: Few studies have investigated retention in HIV care in West Africa. We measured retention in antiretroviral therapy (ART) programmes among people living with HIV and re-engagement in care among those lost to follow up (LTFU) in Guinea and identified ... ...

    Abstract Few studies have investigated retention in HIV care in West Africa. We measured retention in antiretroviral therapy (ART) programmes among people living with HIV and re-engagement in care among those lost to follow up (LTFU) in Guinea and identified associated risk factors using survival analysis. Patient-level data were analysed from 73 ART sites. Treatment interruptions and LTFU were defined as missing a ART refill appointment by over 30 days and by over 90 days respectively. A total of 26,290 patients initiating ART between January 2018 and September 2020 were included in the analysis. The mean age at ART initiation was of 36.2 years, with women accounting for 67% of the cohort. Retention 12 months after ART initiation was 48.7% (95%CI 48.1-49.4%). The LTFU rate was 54.5 per 1000 person-months (95% CI 53.6-55.4), with the peak hazards of LTFU occurring after the first visit and decreasing steadily over time. In an adjusted analysis, the hazards of LTFU were higher among men compared to women (aHR = 1.10; 95%CI 1.08-1.12), being aged 13-25 years old versus older patients (aHR = 1.07; 95%CI = 1.03-1.13), and among those initating ART in smaller health facilities (aHR = 1.52; 95%CI 1.45-1.60). Among 14,683 patients with an LTFU event, 4,896 (33.3%) re-engaged in care, of whom 76% did so within six months from LTFU. The re-engagement rate was 27.1 per 1000 person-months (95%CI 26.3-27.9). Treatment interruptions were correlated with rainfall patterns and end of year mobility patterns. Rates of retention and re-engagement in care are very low in Guinea, undermining the effectiveness and durability of first-line ART regimens. Tracing interventions and differentiated service delivery of ART, including multi-month dispensing may improve care engagement, especially in rural areas. Further research should investigate social and health systems barriers to retention in care.
    Language English
    Publishing date 2023-05-16
    Publishing country United States
    Document type Journal Article
    ISSN 2767-3375
    ISSN (online) 2767-3375
    DOI 10.1371/journal.pgph.0000970
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Correction: Retention in care among people living with HIV in the national antiretroviral therapy programme in Guinea: A retrospective cohort analysis.

    Kadio, Kadio Jean-Jacques Olivier / Cissé, Amadou / Diallo, Thierno Saidou / Guilavogui, Foromo / Tounkara, Adrien Fapeingou / Pe, Damey / Sow, Alhassane / Bah, Fatoumata Fily / Youla, Souleymane Sékou / Diallo, Ibrahima / Leno, Niouma Nestor / Mboungou, Lazare / Ahiatsi, Nyawotope Koffi Arnold / Kaba, Laye / Zeynabou, Sy / Vallès-Casanova, Ignasi / Wringe, Alison / Hoibak, Sarah / Koïta, Youssouf /
    Vallès, Xavier

    PLOS global public health

    2023  Volume 3, Issue 9, Page(s) e0002456

    Abstract: This corrects the article DOI: 10.1371/journal.pgph.0000970.]. ...

    Abstract [This corrects the article DOI: 10.1371/journal.pgph.0000970.].
    Language English
    Publishing date 2023-09-28
    Publishing country United States
    Document type Published Erratum
    ISSN 2767-3375
    ISSN (online) 2767-3375
    DOI 10.1371/journal.pgph.0002456
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: Dataset on the RETRO-BMC cruise onboard the R/V Hespérides, April 2017, Brazil-Malvinas Confluence

    Orúe-Echevarría, Dorleta / Pelegrí, Josep L. / Castellanos, Paola / Guallar, Carles / Marotta, Humberto / Marrasé, Cèlia / Martín, Jacobo / Masdeu-Navarro, Marta / Paniagua, Guillermina F. / Peña-Izquierdo, Jesús / Puigdefábregas, Joan / Rodríguez-Fonseca, Belén / Roget, Elena / Rosell-Fieschi, Miquel / Salat, Jordi / Salvador, Joaquín / Vallès-Casanova, Ignasi / Vidal, Montserrat / Viúdez, Álvaro

    Data in Brief. 2020 June, v. 30

    2020  

    Abstract: This dataset, gathered during the RETRO-BMC cruise, reports multiple-scale measurements at the Confluence of the Brazil and Malvinas Currents. The cruise was carried out between 8 and 28 April 2017 onboard R/V Hespérides, departing from Ushuaia and ... ...

    Abstract This dataset, gathered during the RETRO-BMC cruise, reports multiple-scale measurements at the Confluence of the Brazil and Malvinas Currents. The cruise was carried out between 8 and 28 April 2017 onboard R/V Hespérides, departing from Ushuaia and arriving to Santos. Along its track, the vessel recorded near-surface temperature and salinity, as well as the horizontal flow from 20 m down to about 800 m. A total of 33 hydrographic stations were completed in a region off the Patagonian Shelf, within 41.2°S–35.9°S and out to 53.0°W. At each station, a multiparametric probe and velocity sensors were deployed inside the frame of a rosette used to collect water samples at selected depths; these samples were later used for several water analyses, including inorganic nutrient concentrations. Microstructure measurements were carried out in 11 of these hydrographic stations. In addition, two high-resolution three-dimensional surveys were conducted with an instrumented undulating vehicle between 40.6°S–39.0°S and 55.6°W–53.8°W. Lastly, eight high-frequency vertical profilers were deployed in the region and five position-transmitting drifters were launched. These data allow the description of the Confluence from the regional scale to the microscale, and provide a view of the variability of the frontal region on time scales from days to weeks.
    Keywords data collection ; microstructure ; salinity ; temperature ; Brazil ; Falkland Islands
    Language English
    Dates of publication 2020-06
    Publishing place Elsevier Inc.
    Document type Article
    ZDB-ID 2786545-9
    ISSN 2352-3409
    ISSN 2352-3409
    DOI 10.1016/j.dib.2020.105412
    Database NAL-Catalogue (AGRICOLA)

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  7. Article ; Online: Dataset on the RETRO-BMC cruise onboard the R/V Hespérides, April 2017, Brazil-Malvinas Confluence.

    Orúe-Echevarría, Dorleta / Pelegrí, Josep L / Castellanos, Paola / Guallar, Carles / Marotta, Humberto / Marrasé, Cèlia / Martín, Jacobo / Masdeu-Navarro, Marta / Paniagua, Guillermina F / Peña-Izquierdo, Jesús / Puigdefábregas, Joan / Rodríguez-Fonseca, Belén / Roget, Elena / Rosell-Fieschi, Miquel / Salat, Jordi / Salvador, Joaquín / Vallès-Casanova, Ignasi / Vidal, Montserrat / Viúdez, Álvaro

    Data in brief

    2020  Volume 30, Page(s) 105412

    Abstract: This dataset, gathered during the RETRO-BMC cruise, reports multiple-scale measurements at the Confluence of the Brazil and Malvinas Currents. The cruise was carried out between 8 and 28 April 2017 onboard R/V Hespérides, departing from Ushuaia and ... ...

    Abstract This dataset, gathered during the RETRO-BMC cruise, reports multiple-scale measurements at the Confluence of the Brazil and Malvinas Currents. The cruise was carried out between 8 and 28 April 2017 onboard R/V Hespérides, departing from Ushuaia and arriving to Santos. Along its track, the vessel recorded near-surface temperature and salinity, as well as the horizontal flow from 20 m down to about 800 m. A total of 33 hydrographic stations were completed in a region off the Patagonian Shelf, within 41.2°S-35.9°S and out to 53.0°W. At each station, a multiparametric probe and velocity sensors were deployed inside the frame of a rosette used to collect water samples at selected depths; these samples were later used for several water analyses, including inorganic nutrient concentrations. Microstructure measurements were carried out in 11 of these hydrographic stations. In addition, two high-resolution three-dimensional surveys were conducted with an instrumented undulating vehicle between 40.6°S-39.0°S and 55.6°W-53.8°W. Lastly, eight high-frequency vertical profilers were deployed in the region and five position-transmitting drifters were launched. These data allow the description of the Confluence from the regional scale to the microscale, and provide a view of the variability of the frontal region on time scales from days to weeks.
    Language English
    Publishing date 2020-03-21
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 2786545-9
    ISSN 2352-3409 ; 2352-3409
    ISSN (online) 2352-3409
    ISSN 2352-3409
    DOI 10.1016/j.dib.2020.105412
    Database MEDical Literature Analysis and Retrieval System OnLINE

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