673 research outputs found
Enhanced detection of low-expressed miRNAs in Leishmania-infected macrophages through RNA fractionation and RT-qPCR optimization
No full textPeriod-luminosity diagram of long period variables in the Magellanic Clouds
No full textContext. The period-luminosity diagram (PLD) has proven to be a powerful tool for studying populations of pulsating red giants. Gaia Data Release 2 (DR2) provides a large data set including many long-period variables (LPVs) on which this tool can be applied.
Aims: We investigate the location of LPVs from the Large and Small Magellanic Clouds in the PLD using various optical and infrared luminosity indicators from Gaia and 2MASS, respectively. We thereby distinguish between stars of different masses and surface chemistry.
Methods: The data set taken from the Gaia DR2 catalogue of LPVs allows for a homogeneous study from low- to high-mass LPVs. These sources are divided into sub-populations of asymptotic giant branch (AGB) stars according to their mass and their O- or C-rich nature using the Gaia-2MASS diagram developed by our group. This diagram uses a Wesenheit index WBP, RP based on Wesenheit functions in the Gaia and 2MASS photometric bands. Four different luminosity indicators are used to study the period-luminosity (P-L) relations.
Results: We provide the first observational evidence of a P-L relation offset for both fundamental and 1O pulsators between low- and intermediate-mass O-rich stars, in agreement with published pulsation predictions. Among the luminosity indicators explored, sequence C' is the narrowest in the P-WBP, RP diagram, and is thus to be preferred over the other PLDs for the determination of distances using LPVs. The majority of massive AGB stars and red supergiants form a smooth extension of sequence C of low- and intermediate-mass AGB stars in the P-WBP, RP diagram, suggesting that they pulsate in the fundamental mode. All results are similar in the two Magellanic Clouds
A new method to identify subclasses among AGB stars using Gaia and 2MASS photometry
No full textAims. We explore the wealth of high-quality photometric data provided by data release 2 (DR2) of the Gaia mission for long-period variables (LPVs) in the Large Magellanic Cloud (LMC). Our goal is to identify stars of various types and masses along the asymptotic giant branch. Methods. For this endeavour, we developed a new multi-band approach combining Wesenheit functions WRP,BP−RP and WKs,J−Ks in the Gaia BP, RP, and 2MASS J, Ks spectral ranges, respectively, and use a new diagram, (WRP,BP−RP − WKs,J−Ks) versus Ks, to distinguish between different kinds of stars in our sample of LPVs. We used stellar population synthesis models to validate our approach. Results. We demonstrate the ability of the new diagram to discriminate between O- and C-rich objects, and to identify low-mass, intermediate-mass, and massive O-rich red giants, as well as extreme C-rich stars. Stellar evolution and population synthesis models guide the interpretation of the results, highlighting the diagnostic power of the new tool to discriminate between stellar initial masses, chemical properties, and evolutionary stages
p53-indipendent apoptotic effects of the hepatitis B virus HBx protein in vivo and in vitro.
No full textThe hepatitis B virus protein HBx is a promiscuous transactivator implicated in both cell growth and death and in the development of hepatocellular carcinoma. We recently reported that HBx can potentiate c-myc-induced liver oncogenesis in a transgenic model where low level expression of HBx induces no pathology. To assess if HBx could affect the hepatocyte turnover, we investigated the HBx-elicited apoptotic responses in transgenic livers and in primary hepatocyte cultures. Here we show that transgenic expression of HBx is associated with a twofold increase of spontaneous cell death in the mouse liver. The finding that apoptosis was enhanced to similar extents in HBx mice carrying homozygous p53 null mutations implied that functionally intact p53 was not required to transduce the death signal. A direct, dose-dependent apoptotic function of HBx was demonstrated in transient transfections of liver-derived cell lines. We further show that stable expression of HBx at low, presumably physiological levels in primary hepatocytes, induced cellular susceptibility to diverse apoptotic insults, including growth factor deprivation, treatment with anti-Fas antibodies or doxorubicine and oxidative stress. HBx expression, but not p53 status profoundly affected the commitment of cells to die upon apoptotic stimuli. These data strengthen the notion that HBX may contribute to HBV pathogenesis by enhancing apoptotic death in the chronically infected liver
Développements applicatifs de l’électronique de
No full textL’électronique de spin connaît depuis une vingtaine d’années un essor considérable,
car une grande synergie est très vite apparue entre recherche fondamentale et
développements applicatifs dans plusieurs domaines. Nous présentons ici une vue
d’ensemble de ces applications actuelles et envisagées, dont certaines sont décrites
plus en détail dans les articles de C. Fermon et M. Pannetier-Lecoeur sur les capteurs
magnétiques, et de J.P. Nozières sur les têtes de lecture et les mémoires magnétiques
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