A self-consistent dynamical model of the Milky Way disc adjusted to Gaia data

Context. Accurate astrometry achieved by Gaia for many stars in the Milky Way provides an opportunity to reanalyse the Galactic stellar populations from a large and homogeneous sample and to revisit the Galaxy gravitational potential. Aims. This paper shows how a self-consistent dynamical model can be obtained by fitting the gravitational potential of the Milky Way to the stellar kinematics and densities from Gaia data. Methods. We derived a gravitational potential using the Besancon Galaxy Model, and computed the disc stellar distribution functions based on three integrals of motion (E, Lz, I3) to model stationary stellar discs. The gravitational potential and the stellar distribution functions are built self-consistently, and are then adjusted to be in agreement with the kinematics and the density distributions obtained from Gaia observations. A Markov chain Monte Carlo (MCMC) is used to fit the free parameters of the dynamical model to Gaia parallax and proper motion distributions. The fit is done on several sets of Gaia data, mainly a subsample of the GCNS (Gaia catalogue of nearby stars to 100 pc) with G< 17, together with 26 deep fields selected from eDR3, widely spread in longitudes and latitudes. Results. We are able to determine the velocity dispersion ellipsoid and its tilt for subcomponents of different ages, both varying with R and z. The density laws and their radial scale lengths for the thin and thick disc populations are also obtained self-consistently. This new model has some interesting characteristics that come naturally from the process, such as a flaring thin disc. The thick disc is found to present very distinctive characteristics from the old thin disc, both in density and kinematics. This lends significant support to the idea that thin and thick discs were formed in distinct scenarios, as the density and kinematics transition between them is found to be abrupt. The dark matter halo is shown to be nearly spherical. We also derive the solar motion with regards to the Local Standard of Rest (LSR), finding U· = 10.79 ± 0.56 km s-1, V· = 11.06 ± 0.94 km s-1, and W· = 7.66 ± 0.43 km s-1, in close agreement with recent studies. Conclusions. The resulting fully self-consistent gravitational potential, still axisymmetric, is a good approximation of a smooth mass distribution in the Milky Way and can be used for further studies, including finding streams, substructures, and to compute orbits for real stars in our Galaxy

Deciphering the evolution of the Milky Way discs: Gaia APOGEE Kepler giant stars and the Besançon Galaxy Model

[Context] Thanks to ongoing efforts to compute accurate stellar ages, we are able to characterise stars in different regions of the Milky Way. The Gaia and Kepler space-missions, along with ground-based spectroscopic surveys such as APOGEE, provide a unique way to study the chemo-kinematics relations as a function of age through the Galactic stellar populations and provide new constraints to Galactic evolution models. [Aims] We investigate the properties of the double sequences of the Milky Way discs visible in the [α/Fe] versus [Fe/H] diagram, which are usually associated to the chemical thin and thick discs at the solar circle. In the framework of Galactic formation and evolution, we discuss the complex relationships between age, metallicity, [α/Fe], and the radial, azimuthal, and vertical components of the space velocities. [Methods] We study stars with measured chemical and seismic properties from the APOGEE spectroscopic survey and the Kepler satellite, respectively. In addition, astrometry from the Gaia satellite is available for the majority of the sample. We separate the [α/Fe]-[Fe/H] diagram into three stellar populations: the thin disc, the high-α metal-poor thick disc, and the high-α metal-rich thick disc and characterise each of these in the age-chemo-kinematics parameter space. Because of the model-dependent nature of the ages inferred from asteroseismology, and because they depend on the quality of the input spectroscopic information, we compare results obtained from different APOGEE data releases (DR14 and DR16). We also use age determinations from two recent works in the literature. In addition, we use the Besançon stellar populations synthesis model to highlight selection biases and mechanisms (such as mergers and secular evolution) not included in the model. [Results] The thin disc exhibits a flat age-metallicity relation while [α/Fe] increases with stellar age. We confirm no correlation between radial and vertical velocities with [Fe/H], [α/Fe], and age for each stellar population. Considering both samples, Vφ decreases with age for the thin disc, while Vφ increases with age for the high-α metal-poor thick disc. We show that this difference is not due to sample selection. Although the age distribution of the high-α metal-rich thick disc is very close to that of the high-α metal-poor thick disc between 7 and 14 Gyr, its kinematics seems to follow that of the thin disc. This feature, not predicted by the hypotheses included in the Besançon Galaxy Model, suggests a different origin and history for this population. Finally, we show that there is a maximum dispersion of the vertical velocity, σZ, with age for the high-α metal-poor thick disc around 8 Gyr. The comparisons with the Besançon Galaxy Model simulations suggest a more complex chemo-dynamical scheme to explain this feature, most likely including mergers and radial migration effects.F.F., A.F., R.M., M.R., T.A. acknowledge support by the Spanish Ministry of Science, Innovation and University (MICIU/FEDER, UE) through grant RTI2018-095076-B-C21, the Institute of Cosmos Sciences University of Barcelona (ICCUB, Unidad de Excelencia “María de Maeztu”) through grant CEX2019-000918-M, the Ramon y Cajal Fellowship RYC2018-025968-I. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 800502. AM acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 772293 – project ASTEROCHRONOMETRY, https://www.asterochronometry.eu

Prévalence du tabagisme chez le personnel de l'Hôpital Général de Douala, Cameroun

Introduction: La pr&eacute;valence du tabagisme parmi le personnel de sant&eacute; hospitalier au Cameroun n'est pas connue alors que le tabagisme est en expansion dans ce pays avec 13,2% de fumeurs selon l&rsquo;OMS. Pour combler ce manque une enqu&ecirc;te sur les consommations, les connaissances, opinions et attitudes vis-&agrave;-vis des fumeurs a &eacute;t&eacute; conduite &agrave; l&rsquo;H&ocirc;pital G&eacute;n&eacute;ral de Douala, l&rsquo;un des h&ocirc;pitaux de r&eacute;f&eacute;rence du Cameroun. M&eacute;thodes: Du 1er au 30 Avril 2010, des questionnaires anonymes ont &eacute;t&eacute; distribu&eacute;s par des enqu&ecirc;teurs dans les services ou via les surveillants et recueillis et analys&eacute;s de fa&ccedil;on anonyme. R&eacute;sultats: Sur 402 questionnaires distribu&eacute;s 277 ont &eacute;t&eacute; r&eacute;cup&eacute;r&eacute;s. La pr&eacute;valence de fumeurs est de 3,6% parmi les soignants et de 9,4% parmi les autres personnels soit en moyenne sur l&rsquo;ensemble de l&rsquo;h&ocirc;pital 5,4%. Les produits fum&eacute;s &eacute;taient toujours des cigarettes. L&rsquo;initiation du tabagisme &agrave; souvent &eacute;t&eacute; tardive (21,5 ans) et la d&eacute;pendance est absente ou faible chez 33% des fumeurs. Les personnes pensent que c&rsquo;est leur devoir de questionner sur le tabac et de prendre en charge les fumeurs, mais ils sont presque un sur deux &agrave; ignorer la loi Camerounaise. Conclusion: Le tabagisme chez le personnel hospitalier est une r&eacute;alit&eacute; au Cameroun ; le personnel soignant et les pouvoirs publics devraient s&rsquo;impliquer davantage dans la lutte contre ce fl&eacute;au qui est en expansion dans les pays du sud

Extracellular vesicles generated by placental tissues ex vivo: A transport system for immune mediators and growth factors

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144634/1/aji12860_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144634/2/aji12860.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144634/3/aji12860-sup-0001-Supinfo.pd

The scientific payload of the Ultraviolet Transient Astronomy Satellite (ULTRASAT)

The Ultraviolet Transient Astronomy Satellite (ULTRASAT) is a space-borne near UV telescope with an unprecedented large field of view (200 sq. deg.). The mission, led by the Weizmann Institute of Science and the Israel Space Agency in collaboration with DESY (Helmholtz association, Germany) and NASA (USA), is fully funded and expected to be launched to a geostationary transfer orbit in Q2/3 of 2025. With a grasp 300 times larger than GALEX, the most sensitive UV satellite to date, ULTRASAT will revolutionize our understanding of the hot transient universe, as well as of flaring galactic sources. We describe the mission payload, the optical design and the choice of materials allowing us to achieve a point spread function of ~10arcsec across the FoV, and the detector assembly. We detail the mitigation techniques implemented to suppress out-of-band flux and reduce stray light, detector properties including measured quantum efficiency of scout (prototype) detectors, and expected performance (limiting magnitude) for various objects.Comment: Presented in the SPIE Astronomical Telescopes + Instrumentation 202

Broad-Spectrum Drugs Against Viral Agents

Development of antivirals has focused primarily on vaccines and on treatments for specific viral agents. Although effective, these approaches may be limited in situations where the etiologic agent is unknown or when the target virus has undergone mutation, recombination or reassortment. Augmentation of the innate immune response may be an effective alternative for disease amelioration. Nonspecific, broad-spectrum immune responses can be induced by double-stranded (ds)RNAs such as poly (ICLC), or oligonucleotides (ODNs) containing unmethylated deocycytidyl-deoxyguanosinyl (CpG) motifs. These may offer protection against various bacterial and viral pathogens regardless of their genetic makeup, zoonotic origin or drug resistance

Limited adaptive life-history plasticity in a semelparous spider, Stegodyphus lineatus (Eresidae)

ABSTRACT Strictly semelparous animals may still benefit from retaining a plastic reproductive strategy. In cases where the current, usually single brood is too small to deplete maternal resources, females could increase their fitness through investing in another clutch. This may not always be possible if females are constrained and cannot switch between different reproductive performances, such as feeding of young and egg development. We investigated the existence of plasticity in the semelparous spider Stegodyphus lineatus by drastically reducing brood sizes at different stages of the reproductive cycle. We asked whether: (1) females will be able to produce another clutch while caring for young; (2) production of another clutch is a function of female resources; (3) small broods will be able to benefit from increased female resources. Few females re-laid and those few all had their broods experimentally reduced shortly after hatching. We could not detect a difference in life-history variables between females that re-laid and those that did not. However, producing a new clutch did not prevent females from feeding the remaining offspring from the first brood. Matriphagy occurred only in broods that were reduced shortly before the young normally consume the mother. The timing of the mother&apos;s death was a function of the resources the female had left after brood reduction, namely her body mass. Thus, the spiders are generally plastic in that they possess the potential to invest in a second brood. However, in our experiment, this occurred less often than expected. Either incomplete brood reduction occurs too infrequently to act as a selection pressure for an iteroparous strategy or our reduction was not drastic enough to achieve the expected result

Maternal investment in a spider with suicidal maternal care, Stegodyphus lineatus (Araneae, Eresidae). Oikos 109:614–622

Providing parental care is costly for the parent, but generally beneficial for the young whose survival, growth and reproductive value can be increased. Selection should strongly favour an optimal distribution of parental resources, depending on the relationship between the costs and benefits for parents and their offspring. Parental care is characterized by trade offs in investment, for example between egg size and number of young or providing resources at the egg stage versus the post-hatching stage. Females of the spider Stegodyphus lineatus (Eresidae) produce a single small brood with small eggs and provide the young with regurgitated fluid and later, with their body contents via matriphagy. We asked whether females adjust the investment of resources differentially into eggs, regurgitation feeding and matriphagy, and how maternal investment affects the size of the young at dispersal. We followed the growth of young of broods in the lab and in the field and manipulated brood size in order to determine the pattern of resource allocation. We found that brood size was positively correlated with body mass: larger females had larger broods. Females provided 95% of their body mass to the young, allocating more resources to regurgitation than to matriphagy. Females provided regurgitated food to the young according to the brood size, providing less food when the brood was reduced. Maternal resources had a large influence on offspring mass at dispersal, which is likely to affect their future fitness. The study shows the importance of the female&apos;s body mass and her resource allocation decisions for her reproductive outcome

A self-consistent dynamical model of the Milky Way disc adjusted to Gaia data

International audienceContext. Accurate astrometry achieved by Gaia for many stars in the Milky Way provides an opportunity to reanalyse the Galactic stellar populations from a large and homogeneous sample and to revisit the Galaxy gravitational potential. Aims. This paper shows how a self-consistent dynamical model can be obtained by fitting the gravitational potential of the Milky Way to the stellar kinematics and densities from Gaia data. Methods. We derived a gravitational potential using the Besancon Galaxy Model, and computed the disc stellar distribution functions based on three integrals of motion ( E , L z , I 3 ) to model stationary stellar discs. The gravitational potential and the stellar distribution functions are built self-consistently, and are then adjusted to be in agreement with the kinematics and the density distributions obtained from Gaia observations. A Markov chain Monte Carlo (MCMC) is used to fit the free parameters of the dynamical model to Gaia parallax and proper motion distributions. The fit is done on several sets of Gaia data, mainly a subsample of the GCNS ( Gaia catalogue of nearby stars to 100 pc) with G < 17, together with 26 deep fields selected from eDR3, widely spread in longitudes and latitudes. Results. We are able to determine the velocity dispersion ellipsoid and its tilt for subcomponents of different ages, both varying with R and z . The density laws and their radial scale lengths for the thin and thick disc populations are also obtained self-consistently. This new model has some interesting characteristics that come naturally from the process, such as a flaring thin disc. The thick disc is found to present very distinctive characteristics from the old thin disc, both in density and kinematics. This lends significant support to the idea that thin and thick discs were formed in distinct scenarios, as the density and kinematics transition between them is found to be abrupt. The dark matter halo is shown to be nearly spherical. We also derive the solar motion with regards to the Local Standard of Rest (LSR), finding U ⊙ = 10.79 ± 0.56 km s −1 , V ⊙ = 11.06 ± 0.94 km s −1 , and W ⊙ = 7.66 ± 0.43 km s −1 , in close agreement with recent studies. Conclusions. The resulting fully self-consistent gravitational potential, still axisymmetric, is a good approximation of a smooth mass distribution in the Milky Way and can be used for further studies, including finding streams, substructures, and to compute orbits for real stars in our Galaxy