7 research outputs found
Conception et optimisation de modules pour onduleur mmc de moyenne puissance : commande rapprochée à haute isolation galvanique et packaging 3d
No full textIn this research, the author focuses on both a design optimization for a Medium Voltage Modular Multilevel Converter (MV-MMC) use as a DC/AC or AC/DC converter and gate drivers systems for IGBT modules which are used in this kind of application. For example, the MMC converters are used in Medium-Voltage Direct Current (MVDC) electrical ship power systems. For such application, according to IEEE document, the DC bus voltage can be up to 35kV. Hence, gate drivers’ systems for IGBT modules for MVDC-MMC applications are major concerns in terms of architectures and insulation voltage capabilities. Thus, this dissertation provides solutions to answer these problems. The study also includes the studies of a dielectric material which is used as insulation material. The results of experimental tests of a proposed dielectric material for different layers thicknesses to sustain different insulation voltage levels are also provided to clearly validate this study. Actually, a MMC converter composes of a number of converter cells connected in series. One cell (converter’s sub-module) is classically composed of two IGBT modules. Based on the cell topology, a challenged gate driver’s architecture for power semiconductor modules is proposed and compared to the classical one in terms of high and low galvanic insulation voltage levels’ requirements, converter’s cell size, etc.Dans cette recherche, l'auteur met l'accent à la fois sur une optimisation de la conception pour une (MV-MMC: Medium Voltage Modular Multilevel Converter) utiliser comme un DC/AC ou AC/DC et à deuxième fois sur la grille pour les modules IGBT qui sont utilisés dans ce type d'application. Par exemple, les convertisseurs de MMC sont utilisés dans les systèmes d'alimentation des navires électriques avec les buses de moyenne tension de courant continu (en anglais: medium-voltage direct current (MVDC)). Pour une telle application, selon le document IEEE, la tension du bus DC peut être jusqu'à 35kV. Par conséquent, les systèmes de commande rapprochée pour piloter le grille des modules IGBT pour les applications MVDC-MMC sont des principaux problèmes en termes d'architectures et des besoins de haute isolation galvanique. Ainsi, cette thèse fournit des solutions pour répondre à ces problèmes. L'étude inclut également les études d'un matériau diélectrique qui est utilisé comme matériau d'isolation. Les résultats des essais expérimentaux d'un matériau diélectrique proposé pour différentes épaisseurs des couches pour maintenir des niveaux de tension d'isolation sont également fournis pour valider clairement cette étude. En effet, un convertisseur MMC compose d'un certain nombre de cellules de conversion connectés en série. Une cellule (sous-module de convertisseur) est classiquement constitué de deux modules IGBT. Sur la base de la topologie de la cellule, l'architecture d'un pilote de grille contestée pour les modules de puissance à semi-conducteurs est proposée et comparée à celle classique en termes de besoins des niveaux de tension d'isolation galvanique, la taille de la cellule de convertisseur, etc
Using an interactive activity, key informants place photographs of their nominated contacts on a mat at varying distances from themselves representing the strength of social connection across talking, work-related and health-related networks.
No full textAuthor Clarence Tam is the photographer for this figure.</p
Placement of participants’ household and individual unique IDs on a photo album page.
No full textAuthor Clarence Tam is the photographer for this figure.</p
In-vitro assessment of cutaneous immune responses to aedes mosquito salivary gland extract and dengue virus in Cambodian individuals
No full textInternational audienceDengue virus (DENV) poses a global health threat, affecting millions individuals annually with no specific therapy and limited vaccines. Mosquitoes, mainly Aedes aegypti and Aedes albopictus worldwide, transmit DENV through their saliva during blood meals. In this study, we aimed to understand how Aedes mosquito saliva modulate skin immune responses during DENV infection in individuals living in mosquito-endemic regions. To accomplish this, we dissociated skin cells from Cambodian volunteers and incubated them with salivary gland extract (SGE) from three different mosquito strains: Ae. aegypti USDA strain, Ae. aegypti and Ae. albopictus wild type (WT) in the presence/absence of DENV. We observed notable alterations in skin immune cell phenotypes subsequent to exposure to Aedes salivary gland extract (SGE). Specifically, exposure lead to an increase in the frequency of macrophages expressing chemokine receptor CCR2, and neutrophils expressing CD69. Additionally, we noted a substantial increase in the percentage of macrophages that became infected with DENV in the presence of Aedes SGE. Differences in cellular responses were observed when Aedes SGE of three distinct mosquito strains were compared. Our findings deepen the understanding of mosquito saliva's role in DENV infection and skin immune responses in individuals regularly exposed to mosquito bites. This study provides insights into skin immune cell dynamics that could guide strategies to mitigate DENV transmission and other arbovirus diseases
Data_Sheet_1_Rapid Generation of In-House Serological Assays Is Comparable to Commercial Kits Critical for Early Response to Pandemics: A Case With SARS-CoV-2.PDF
No full textIntroductionAccurate and sensitive measurement of antibodies is critical to assess the prevalence of infection, especially asymptomatic infection, and to analyze the immune response to vaccination during outbreaks and pandemics. A broad variety of commercial and in-house serological assays are available to cater to different laboratory requirements; however direct comparison is necessary to understand utility.Materials and MethodsWe investigate the performance of six serological methods against SARS-CoV-2 to determine the antibody profile of 250 serum samples, including 234 RT-PCR-confirmed SARS-CoV-2 cases, the majority with asymptomatic presentation (87.2%) at 1–51 days post laboratory diagnosis. First, we compare to the performance of two in-house antibody assays: (i) an in-house IgG ELISA, utilizing UV-inactivated virus, and (ii) a live-virus neutralization assay (PRNT) using the same Cambodian isolate as the ELISA. In-house assays are then compared to standardized commercial anti-SARS-CoV-2 electrochemiluminescence immunoassays (Elecsys ECLIAs, Roche Diagnostics; targeting anti-N and anti-S antibodies) along with a flow cytometry based assay (FACS) that measures IgM and IgG against spike (S) protein and a multiplex microsphere-based immunoassay (MIA) determining the antibodies against various spike and nucleoprotein (N) antigens of SARS-CoV-2 and other coronaviruses (SARS-CoV-1, MERS-CoV, hCoVs 229E, NL63, HKU1).ResultsOverall, specificity of assays was 100%, except for the anti-S IgM flow cytometry based assay (96.2%), and the in-house IgG ELISA (94.2%). Sensitivity ranged from 97.3% for the anti-S ECLIA down to 76.3% for the anti-S IgG flow cytometry based assay. PRNT and in-house IgG ELISA performed similarly well when compared to the commercial ECLIA: sensitivity of ELISA and PRNT was 94.7 and 91.1%, respectively, compared to S- and N-targeting ECLIA with 97.3 and 96.8%, respectively. The MIA revealed cross-reactivity of antibodies from SARS-CoV-2-infected patients to the nucleocapsid of SARS-CoV-1, and the spike S1 domain of HKU1.ConclusionIn-house serological assays, especially ELISA and PRNT, perform similarly to commercial assays, a critical factor in pandemic response. Selection of suitable immunoassays should be made based on available resources and diagnostic needs.</p
Rapid Generation of In-House Serological Assays Is Comparable to Commercial Kits Critical for Early Response to Pandemics: A Case With SARS-CoV-2
No full textINTRODUCTION: Accurate and sensitive measurement of antibodies is critical to assess the prevalence of infection, especially asymptomatic infection, and to analyze the immune response to vaccination during outbreaks and pandemics. A broad variety of commercial and in-house serological assays are available to cater to different laboratory requirements; however direct comparison is necessary to understand utility. MATERIALS AND METHODS: We investigate the performance of six serological methods against SARS-CoV-2 to determine the antibody profile of 250 serum samples, including 234 RT-PCR-confirmed SARS-CoV-2 cases, the majority with asymptomatic presentation (87.2%) at 1–51 days post laboratory diagnosis. First, we compare to the performance of two in-house antibody assays: (i) an in-house IgG ELISA, utilizing UV-inactivated virus, and (ii) a live-virus neutralization assay (PRNT) using the same Cambodian isolate as the ELISA. In-house assays are then compared to standardized commercial anti-SARS-CoV-2 electrochemiluminescence immunoassays (Elecsys ECLIAs, Roche Diagnostics; targeting anti-N and anti-S antibodies) along with a flow cytometry based assay (FACS) that measures IgM and IgG against spike (S) protein and a multiplex microsphere-based immunoassay (MIA) determining the antibodies against various spike and nucleoprotein (N) antigens of SARS-CoV-2 and other coronaviruses (SARS-CoV-1, MERS-CoV, hCoVs 229E, NL63, HKU1). RESULTS: Overall, specificity of assays was 100%, except for the anti-S IgM flow cytometry based assay (96.2%), and the in-house IgG ELISA (94.2%). Sensitivity ranged from 97.3% for the anti-S ECLIA down to 76.3% for the anti-S IgG flow cytometry based assay. PRNT and in-house IgG ELISA performed similarly well when compared to the commercial ECLIA: sensitivity of ELISA and PRNT was 94.7 and 91.1%, respectively, compared to S- and N-targeting ECLIA with 97.3 and 96.8%, respectively. The MIA revealed cross-reactivity of antibodies from SARS-CoV-2-infected patients to the nucleocapsid of SARS-CoV-1, and the spike S1 domain of HKU1. CONCLUSION: In-house serological assays, especially ELISA and PRNT, perform similarly to commercial assays, a critical factor in pandemic response. Selection of suitable immunoassays should be made based on available resources and diagnostic needs
Mortality and its determinants in antiretroviral treatment-naive HIV-infected children with suspected tuberculosis : an observational cohort study
No full textBackground Tuberculosis is a major cause of morbidity and mortality in HIV-infected children, but is difficult to diagnose. We studied mortality and its determinants in antiretroviral treatment (ART)-naive HIV-infected children presenting with suspected tuberculosis. Methods In this observational cohort study, HIV-infected children aged 13 years or younger with suspected tuberculosis were followed up for 6 months as part of the ANRS 12229 PAANTHER 01 cohort in eight hospitals in four countries (Burkina Faso, Cambodia, Cameroon, and Vietnam). Children started ART and antituberculosis treatment at the clinician's discretion and were retrospectively classified into one of three groups by tuberculosis documentation: confirmed by culture or Xpert MTB/RIF, unconfirmed, and unlikely. We assessed mortality and associated factors using Kaplan-Meier methods and Cox proportional hazard models. The ANRS 12229 PAANTHER 01 study is registered at ClinicalTrials. gov, number NCT01331811. Findings 266 (61%) of 438 children enrolled in the study between April 27, 2011, and May 31, 2014, were ART-naive and included in the analysis (40 had confirmed tuberculosis, 119 unconfirmed tuberculosis, and 107 unlikely tuberculosis). 112.5 person-years of follow-up were available. 154 children (58%) started antituberculosis treatment and 212 (80%) started ART. 50 children (19%) died. Mortality by 6 months was higher in children with confirmed tuberculosis (14 deaths; 2 month survival probability 65.0% [95% CI 50.2-79.8]) compared with unconfirmed tuberculosis (19 deaths; 83.5% [76.8-90.3]) and unlikely tuberculosis (17 deaths; 83.5% [76.3-90.7]; log-rank p=0.0141) and was lower in children with confirmed or unconfirmed tuberculosis who started antituberculosis treatment (p<0.0001 for both). In a multivariate analysis, ART started during the first month of follow-up (hazard ratio 0.08; 95% CI 0.01-0.67), confirmed tuberculosis (6.33; 2.15-18.64), young age (5.90; 2.02-17.19), CD4 less than 10% (2.63; 1.25-5.53), miliary features (4.08; 1.56-10.66), and elevated serum transaminases (4.40; 1.82-10.65) were all independently associated with mortality. Interpretation In our cohort, mortality was high in the first 6 months after suspicion of tuberculosis in ART-naive children. ART should be started early, particularly in children with factors associated with high mortality. Documented or empirical tuberculosis treatment decision should be accelerated to reduce mortality and allow early ART initiation
