Disentangling stellar activity and planetary signals

High-precision radial-velocimetry (RV) is until now the more efficient way to discover planetary systems. Moreover, photometric transit search missions like CoRoT and Kepler, need spectroscopic RV measurements to establish the planetary nature of a transit candidate and to measure the true mass. An active star has on its photosphere dark spots and bright plages rotating with the star. These inhomogeneities of the stellar surface can induce a variation of the measurement of the RV, due to changes in lines shapes and not to a Doppler motion of the star (e.g. Queloz et al. 2001; Desort et al. 2007; Boisse et al. 2009). We study how the Keplerian fit used to search for planets in RV data is confused by spots and we test an approach to subtract RV jitter based on harmonic decomposition of the star rotation. We use simulations of spectroscopic measurements of rotating spotted stars and validate our approach on active stars monitored by high-precision spectrograph HARPS: CoRoT-7 and ι Ho

Genetic diversity and population structure of Botryosphaeria dothidea and Neofusicoccum parvum on English walnut (Juglans regia L.) in France.

Botryosphaeriaceae species are the major causal agents of walnut dieback worldwide, along with Diaporthe species. Botryosphaeria dothidea and Neofusicoccum parvum are the only two Botryosphaeriaceae species associated with this recently emergent disease in France, and little is known about their diversity, structure, origin and dispersion in French walnut orchards. A total of 381 isolates of both species were genetically typed using a sequence-based microsatellite genotyping (SSR-seq) method. This analysis revealed a low genetic diversity and a high clonality of these populations, in agreement with their clonal mode of reproduction. The genetic similarity among populations, regardless of the tissue type and the presence of symptoms, supports the hypothesis that these pathogens can move between fruits and twigs and display latent pathogen lifestyles. Contrasting genetic patterns between N. parvum populations from Californian and Spanish walnut orchards and the French ones suggested no conclusive evidence for pathogen transmission from infected materials. The high genetic similarity with French vineyards populations suggested instead putative transmission between these hosts, which was also observed with B. dothidea populations. Overall, this study provides critical insight into the epidemiology of two important pathogens involved in the emerging dieback of French walnut orchards, including their distribution, potential to mate, putative origin and disease pathways

The CADM1 tumor suppressor gene is a major candidate gene in MDS with deletion of the long arm of chromosome 11.

Myelodysplastic syndromes (MDS) represent a heterogeneous group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis leading to peripheral cytopenias and in a substantial proportion of cases to acute myeloid leukemia. The deletion of the long arm of chromosome 11, del(11q), is a rare but recurrent clonal event in MDS. Here, we detail the largest series of 113 cases of MDS and myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN) harboring a del(11q) analyzed at clinical, cytological, cytogenetic, and molecular levels. Female predominance, a survival prognosis similar to other MDS, a low monocyte count, and dysmegakaryopoiesis were the specific clinical and cytological features of del(11q) MDS. In most cases, del(11q) was isolated, primary and interstitial encompassing the 11q22-23 region containing ATM, KMT2A, and CBL genes. The common deleted region at 11q23.2 is centered on an intergenic region between CADM1 (also known as Tumor Suppressor in Lung Cancer 1) and NXPE2. CADM1 was expressed in all myeloid cells analyzed in contrast to NXPE2. At the functional level, the deletion of Cadm1 in murine Lineage-Sca1+Kit+ cells modifies the lymphoid-to-myeloid ratio in bone marrow, although not altering their multilineage hematopoietic reconstitution potential after syngenic transplantation. Together with the frequent simultaneous deletions of KMT2A, ATM, and CBL and mutations of ASXL1, SF3B1, and CBL, we show that CADM1 may be important in the physiopathology of the del(11q) MDS, extending its role as tumor-suppressor gene from solid tumors to hematopoietic malignancies

Développer le questionnement, l’ouverture sur le monde et la prise de décision responsable en Ecole d’ingénieur

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Physical absorption of volatile organic compounds by spraying emulsion in a spray tower: experiments and modelling

This study outlines a volatile organic compounds (VOCs) removal spray tower consisting of an empty cylindrical vessel and nozzles spraying an oil/water emulsion into the vessel. Spraying an emulsion into a spray tower absorbs both lipophilic and hydrophilic compounds, facilitates oil transport, improves the interfacial area (oil coats water droplets) and increases the turbulent flow regime enhancing mass transfer. Toluene was chosen as the synthetic lipophilic pollutant. The choice of the organic absorbent, silicone oil (47v350 Rhordorsil (R)), was made by considering several properties: thermal and mechanical stability, non-biodegradable nature, insolubility in water and low value of Henry's constant. Gas-liquid mass transfer and the hydrodynamics of the gas-liquid contactor were thoroughly investigated. It was observed that emulsion spraying allowed the dual absorption of hydro- and lipophylic VOCs (efficiency around 90% for both) and strongly enhanced the liquid mass transfer coefficient. Finally, a model describing the efficiency of the process as a function of time was developed. The predicted values are in good agreement with the experimental results

First results of the ISSI workshop on the comparison of 1D photochemical models of Titan atmosphere.

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SPIRou spectropolarimetry of the T Tauri star TW Hydrae: magnetic fields, accretion and planets

International audienceIn this paper we report near-infrared observations of the classical T Tauri star TW Hya with the SPIRou high-resolution spectropolarimeter and velocimeter at the 3.6-m Canada-France-Hawaii Telescope in 2019, 2020, 2021 and 2022. By applying Least-Squares Deconvolution (LSD) to our circularly polarized spectra, we derived longitudinal fields that vary from year to year from -200 to +100 G, and exhibit low-level modulation on the 3.6 d rotation period of TW Hya, despite the star being viewed almost pole-on. We then used Zeeman-Doppler Imaging to invert our sets of unpolarized and circularly-polarized LSD profiles into brightness and magnetic maps of TW Hya in all 4 seasons, and obtain that the large-scale field of this T Tauri star mainly consists of a 1.0-1.2 kG dipole tilted at about 20° to the rotation axis, whereas the small-scale field reaches strengths of up to 3-4 kG. We find that the large-scale field is strong enough to allow TW Hya to accrete material from the disc on the polar regions at the stellar surface in a more or less geometrically stable accretion pattern, but not to succeed in spinning down the star. We also report the discovery of a radial velocity signal of semiamplitude 11.1+3.3-2.6 m s-1 (detected at 4.3 ) at a period of 8.3 d in the spectrum of TW Hya, whose origin may be attributed to either a non-axisymmetric density structure in the inner accretion disc, or to a 0.55+0.17-0.13 Jupiter mass candidate close-in planet (if orbiting in the disc plane), at an orbital distance of 0.075 ± 0.001 au

PAX5-ELN oncoprotein promotes multistep B-cell acute lymphoblastic leukemia in mice

International audiencePAX5 is a well-known haploinsufficient tumor suppressor gene in human B-cell precursor acute lymphoblastic leukemia (B-ALL) and is involved in various chromosomal translocations that fuse a part of PAX5 with other partners. However, the role of PAX5 fusion proteins in BALL initiation and transformation is ill-known. We previously reported a new recurrent t(7;9)(q11;p13) chromosomal translocation in human BALL that juxtaposed PAX5 to the coding sequence of elastin (ELN). To study the function of the resulting PAX5-ELN fusion protein in BALL development, we generated a knockin mouse model in which the PAX5-ELN transgene is expressed specifically in B cells. PAX5-ELN-expressing mice efficiently developed BALL with an incidence of 80%. Leukemic transformation was associated with recurrent secondary mutations on Ptpn11, Kras, Pax5, and Jak3 genes affecting key signaling pathways required for cell proliferation. Our functional studies demonstrate that PAX5-ELN affected B-cell development in vitro and in vivo featuring an aberrant expansion of the pro-B cell compartment at the preleukemic stage. Finally, our molecular and computational approaches identified PAX5-ELN-regulated gene candidates that establish the molecular bases of the pre-leukemic state to drive BALL initiation. Hence, our study provides a new in vivo model of human BALL and strongly implicates PAX5 fusion proteins as potent oncoproteins in leukemia development