Vorticity statistics in the two-dimensional enstrophy cascade

We report the first extensive experimental observation of the two-dimensional enstrophy cascade, along with the determination of the high order vorticity statistics. The energy spectra we obtain are remarkably close to the Kraichnan Batchelor expectation. The distributions of the vorticity increments, in the inertial range, deviate only little from gaussianity and the corresponding structure functions exponents are indistinguishable from zero. It is thus shown that there is no sizeable small scale intermittency in the enstrophy cascade, in agreement with recent theoretical analyses.Comment: 5 pages, 7 Figure

Impact of Vitamin D Supplementation on Influenza Vaccine Response and Immune Functions in Deficient Elderly Persons: A Randomized Placebo-Controlled Trial

Background: Immunosenescence contributes to reduced vaccine response in elderly persons, and is worsened by deficiencies in nutrients such as Vitamin (Vit-D). The immune system is a well-known target of Vit-D, which can both potentiate the innate immune response and inhibit the adaptive system, and so modulate vaccination response.Objective: This randomized placebo-controlled double-blind trial investigated whether Vit-D supplementation in deficient elderly persons could improve influenza seroprotection and immune response.Design: Deficient volunteers (Vit-D serum <30 ng/mL) were assigned (V1) to receive either 100,000 IU/15 days of cholecalciferol (D, n = 19), or a placebo (P, n = 19), over a 3 month period. Influenza vaccination was performed at the end of this period (V2), and the vaccine response was evaluated 28 days later (V3). At each visit, serum cathelicidin, immune response to vaccination, plasma cytokines, lymphocyte phenotyping, and phagocyte ROS production were assessed.Results: Levels of serum 25-(OH)D increased after supplementation (D group, V1 vs. V2: 20.7 ± 5.7 vs. 44.3 ± 8.6 ng/mL, p < 0.001). No difference was observed for serum cathelicidin levels, antibody titers, and ROS production in D vs. P groups at V3. Lower plasma levels of TNFα (p = 0.040) and IL-6 (p = 0.046), and higher ones for TFGβ (p = 0.0028) were observed at V3. The Th1/Th2 ratio was lower in the D group at V2 (D: 0.12 ± 0.05 vs. P: 0.18 ± 0.05, p = 0.039).Conclusions: Vit-D supplementation promotes a higher TGFβ plasma level in response to influenza vaccination without improving antibody production. This supplementation seems to direct the lymphocyte polarization toward a tolerogenic immune response. A deeper characterization of metabolic and molecular pathways of these observations will aid in the understanding of Vit-D's effects on cell-mediated immunity in aging. This clinical trial was registered at clinicaltrials.gov as NCT01893385

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer, studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory, a versatile observatory designed to address the Hot and Energetic Universe science theme, selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), it aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR, browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters. Finally we briefly discuss on the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, and touch on communication and outreach activities, the consortium organisation, and finally on the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. (abridged).Comment: 48 pages, 29 figures, Accepted for publication in Experimental Astronomy with minor editin

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory. Athena is a versatile observatory designed to address the Hot and Energetic Universe science theme, as selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), X-IFU aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over a hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR (i.e. in the course of its preliminary definition phase, so-called B1), browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters, such as the instrument efficiency, spectral resolution, energy scale knowledge, count rate capability, non X-ray background and target of opportunity efficiency. Finally, we briefly discuss the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, touch on communication and outreach activities, the consortium organisation and the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. The X-IFU will be provided by an international consortium led by France, The Netherlands and Italy, with ESA member state contributions from Belgium, Czech Republic, Finland, Germany, Poland, Spain, Switzerland, with additional contributions from the United States and Japan.The French contribution to X-IFU is funded by CNES, CNRS and CEA. This work has been also supported by ASI (Italian Space Agency) through the Contract 2019-27-HH.0, and by the ESA (European Space Agency) Core Technology Program (CTP) Contract No. 4000114932/15/NL/BW and the AREMBES - ESA CTP No.4000116655/16/NL/BW. This publication is part of grant RTI2018-096686-B-C21 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. This publication is part of grant RTI2018-096686-B-C21 and PID2020-115325GB-C31 funded by MCIN/AEI/10.13039/501100011033

Effets métaboliques de variations du statut en folates chez le rat adulte (étude du protéome hépatique et de l'équilibre rédox)

Les folates (ou vitamines B9) jouent un rôle fondamental en tant que donneurs de méthyl dans le métabolisme des acides aminés et des acides nucléiques. Dans les pays industrialisés, la carence en cette vitamine est rare, mais des groupes à risque de déficience existent, incluant notamment les femmes enceintes et les personnes âgées. Or, les données épidémiologiques montrent que la déficience en folates et son principal corollaire, l'hyperhomocystéinémie, constituent des facteurs de risques de morbidité voire de mortalité, contribuant notamment chez les femmes enceintes à une augmentation du risque de malformations fœtales appelées anomalies de fermeture du tube neural (AFTN), et chez les personnes âgées à une augmentation du risque de maladies dégénératives. Il est établi que la supplémentation péri-conceptionnelle en folates des jeunes femmes est efficace pour prévenir la survenue des AFTN. Un effet bénéfique des folates vis-à-vis des pathologies dégénératives est également suggéré, via un effet hypohomocystéinémiant ou direct, notamment anti-oxydant. Toutefois, peu de connaissances sont encore disponibles sur les conséquences métaboliques exactes de variations du statut en folates. C'est pourquoi nous avons cherché à déterminer dans un 1er temps les conséquences d'une déficience nutritionnelle en folates sur le protéome hépatique du rat adulte. Nous avons pu identifier 9 protéines différemment exprimées dans le foie des rats déficients en folates et hyperhomocystéinémiques. Ces protéines interviennent dans des voies métaboliques diverses, certaines pouvant être associées à la défense anti-oxydante (glutathion péroxydase 1, GPx 1, notamment) ou à la carcinogenèse (e. g., cofiline 1 et MAWDBP). Nous avons de plus montré que la MAWDBP existe au niveau hépatique sous plusieurs formes dont la présence semble dépendante du statut en folates des animaux. La nature de la modification à l'origine de ces différentes formes n'a pas encore pu être déterminée. Nos résultats suggèrent qu'elle ne serait pas associée à différents niveaux de phosphorylation de la protéine, mais ils nécessitent d'être confirmés par des approches complémentaires. Nous avons dans un 2ème temps cherché à déterminer les effets de variations de l'apport et du statut en folates sur l'équilibre rédox du rat adulte. Les résultats obtenus montrent que la déficience sévère en folates perturbe cet équilibre en modifiant parallèlement à l'induction d'une hyperhomocystéinémie plusieurs marqueurs de la protection anti-oxydante plasmatique et tissulaire, témoignant de la génération d'un stress oxydant. Nous avons également observé la mise en place d'une réponse anti-oxydante au niveau hépatique pour contrecarrer ce stress, qui pourrait impliquer plus particulièrement le glutathion. Nous n'avons néanmoins pas observé un effet anti-oxydant ou hypohomocystéinémiant dans le cas d'apports élevés en folates comparativement à un apport couvrant les besoins des animaux. En conclusion, la présente thèse ouvre de nouvelles perspectives pour la compréhension des mécanismes mis en jeu dans les effets métaboliques de la déficience en folates. Les études futures viseront notamment à déterminer la nature des mécanismes impliqués dans la régulation par les folates de l'expression des protéines identifiées au cours de l'analyse protéomique, et à préciser leur implication dans l'association existant entre la déficience en folates et le risque de pathologies dégénératives. Il sera également important d'approfondir la compréhension des mécanismes anti-oxydants mis en place en réponse à la déficience en folates, et en particulier de déterminer le rôle du glutathion et de la régulation de son métabolisme à ce niveau.CLERMONT FD-BCIU-Santé (631132104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Transport and steady-state accumulation of putrescine in brush-border membrane vesicles of rabbit small intestine

International audienc

Linear hydrodynamic instability of circular jets with thin shear layers

International audienc

Selective sites for polyamine binding to rabbit intestinal brush-border membranes

International audienc

Proteomic analysis identifies cytoskeleton-interacting proteins as major downstream targets of altered folate status in the aorta of adult rat

International audienceScope: Mild folate deficiency and subsequently elevated plasma level of homocysteine are associated with an increased risk for vascular diseases in adults. Conversely, high intakes of folic acid (FA) may have beneficial effects on vascular function, presumably in part through homocysteine lowering. However, these effects have not yet been translated in terms of prevention or treatment of vascular pathologies. Besides, the complex biologic perturbation induced by variations of the folate supply is still not fully deciphered. We thus carried out a proteomic analysis of the aorta of adult rats after a dietary FA depletion or supplementation. Methods and results: Nine month-old rats were fed a FA-depleted, FA-supplemented or control diet for 8 weeks. Total proteins from adventitia-free aortas were separated by 2DE and differentially expressed proteins were identified by MS. FA depletion or supplementation resulted in significantly changed abundance of 29 spots (p < 0.05), of which 20 proteins were identified. Bioinformatic analysis revealed that most of these proteins are involved in cytoskeleton-related processes important to cell function/maintenance, assembly/organization, and movement. Conclusion: Our proteomic study supports that expression of proteins essential to vascular structure and, presumably, function is modulated by high intake as well as deprivation of FA