5,604 research outputs found
Modified gravity models and the central cusp of dark matter haloes in galaxies
The N-body dark matter (DM) simulations point that DM density profiles, e.g. the Navarro Frenk White (NFW) halo, should be cuspy in its centre, but observations disfavour this kind of DM profile. Here we consider whether the observed rotation curves close to the galactic centre can favour modified gravity models in comparison to the NFW halo, and how to quantify such difference. Two explicit modified gravity models are considered, Modified Newtonian Dynamics (MOND) and a more recent approach renormalization group effects in general relativity (RGGR). It is also the purpose of this work to significantly extend the sample on which RGGR has been tested in comparison to other approaches. By analysing 62 galaxies from five samples, we find that (i) there is a radius, given by half the disc scale length, below which RGGR and MOND can match the data about as well or better than NFW, albeit the formers have fewer free parameters; (ii) considering the complete rotation curve data, RGGR could achieve fits with better agreement than MOND, and almost as good as a NFW halo with two free parameters (NFW and RGGR have, respectively, two and one more free parameters than MOND)
The Herschel exploitation of local galaxy Andromeda (HELGA) V: Strengthening the case for substantial interstellar grain growth
In this paper we consider the implications of the distributions of dust and
metals in the disc of M31. We derive mean radial dust distributions using a
dust map created from Herschel images of M31 sampling the entire far-infrared
(FIR) peak. Modified blackbodies are fit to approximately 4000 pixels with a
varying, as well as a fixed, dust emissivity index (beta). An overall metal
distribution is also derived using data collected from the literature. We use a
simple analytical model of the evolution of the dust in a galaxy with dust
contributed by stellar sources and interstellar grain growth, and fit this
model to the radial dust-to-metals distribution across the galaxy. Our analysis
shows that the dust-to-gas gradient in M31 is steeper than the metallicity
gradient, suggesting interstellar dust growth is (or has been) important in
M31. We argue that M31 helps build a case for cosmic dust in galaxies being the
result of substantial interstellar grain growth, while the net dust production
from stars may be limited. We note, however, that the efficiency of dust
production in stars, e.g., in supernovae (SNe) ejecta and/or stellar
atmospheres, and grain destruction in the interstellar medium (ISM) may be
degenerate in our simple model. We can conclude that interstellar grain growth
by accretion is likely at least as important as stellar dust production
channels in building the cosmic dust component in M31.Comment: 12 pages, 7 figures. Published in MNRAS 444, 797. This version is
updated to match the published versio
Three-dimensional VP and VP/VS models of the upper crust in the Friuli area (northeastern Italy)
3-D images of P velocity and P-to S-velocity ratio have been produced for the upper crust of the Friuli area (northeastern Italy) using local earthquake tomography. The data consist of 2565 P and 930 S arrival times of high quality. The best-fitting VP and VP/VS 1-D models were computed before the 3-D inversion. VP was measured on two rock samples representative of the investigated upper layers of the Friuli crust. The tomographic VP model was used for modelling the gravity anomalies, by converting the velocity values into densities along three vertical cross-sections. The computed gravity anomalies were optimized with respect to the observed gravity anomalies. The crust investigated is characterized by sharp lateral and deep VP and VP/VS anomalies that are associated with the complex geological structure. High VP/VS values are associated with highly fractured zones related to the main faulting pattern. The relocated seismicity is generally associated with sharp variations in the VP/VS anomalies. The VP images show a high-velocity body below 6 km depth in the central part of the Friuli area, marked also by strong VP/VS heterogeneities, and this is interpreted as a tectonic wedge. Comparison with the distribution of earthquakes supports the hypothesis that the tectonic wedge controls most of the seismicity and can be considered to be the main seismogenic zone in the Friuli are
Common staining techniques for highlighting Acanthamoeba cysts
A 36-year-old woman returning from holiday in Portugal presented with bilateral ocular pain and acute visual loss. Eye examination revealed an inflammation in the anterior segment associated with corneal keratitis. During her trip, she wore contact lenses and rinsed the storage case using tap water. Corneal scrapings, contact lenses and cleaning solution from the case were inoculated onto agar plates supplemented with heat-inactivated bacteria. Bilateral Acanthamoeba keratitis was diagnosed, as microscopic examination of cultures from the last two samples revealed typical, spherical double-walled cystic structures (Fig. 1)
Post-international adoption medical follow-up at the Angers university hospital between 2009 and 2012.
OBJECTIVE: The authors had for aim to describe infectious diseases in internationally adopted child at arrival in France.
PATIENTS AND METHODS: We made a retrospective descriptive study of the children\u27s files having undergone medical check-ups between 2009 and 2012.
RESULTS: One hundred and eighty-two files were included: 80% of the children came from Africa, 15% from South America and the Caribbean, 3% from Asia, and 2% from Europe. Forty-three percent were diagnosed with tinea. HIV, hepatitis C, and syphilis blood tests were all negative. Six children presented with acute or chronic hepatitis B, another 5 children with acute hepatitis A. One blood test for cysticercosis was positive. Two children presented with malaria. 58% of the children carried an intestinal parasite; the most prevalent was Giardia duodenalis. Bacteriological stool culture was positive for 17 children, for 9 with an antibiotic resistant bacterium. Twenty-seven children had a positive virological stool culture, 2 for a poliovirus.
CONCLUSION: A systematic infectious check-up should be performed for a child adopted internationally when he/she arrives in France. This allows diagnosing diseases requiring an emergency treatment, or asymptomatic but severe diseases when chronic. Some blood tests must be double-checked when the child arrives, because of possible false negative initial tests results in the country of origin. Screening, early treatment, and implementing prophylaxis can decrease the risk of transmission to relatives. It also allows monitoring the antimicrobial resistance of some pathogens and the reintroduction of the poliovirus in France
Actuación religiosa de civiles españoles en la orden tercera de San Francisco en Buenos Aires: 1725-1823
The present article takes part in two historical times: the modem one and the contemporaneous one due to the long-lasting of the evolution of one civil and religious order in Buenos Aires: Franciscan Third Order. This Order had a remarkable significance because of the spiritual and social evolution of her members.<br><br>La presente comunicación se inserta en dos tiempos históricos: el moderno y el contemporáneo debido a la larga duración de la trayectoria de una orden civil-religiosa en Buenos Aires: la Orden Tercera de San Francisco. Ésta tuvo una notable trascendencia por el recorrido espiritual y social efectuado por los miembros que la compusieron
Protection personnelle antivectorielle
Les vecteurs des agents du paludisme ou de la leishmaniose, rencontrés lors de voyages dans les régions à climat chaud, s'ajoutant à la transmission par le moustique tigre (Aedes albopictus) des virus chikungunya et de la dengue dans le sud de la France, ont montré l'intérêt d'une réflexion approfondie sur la protection personnelle antivectorielle. En cas d'épidémie, nos concitoyens se protègent individuellement en se procurant sur le marché tout un arsenal de moyens où le meilleur côtoie le pire. Pour donner à chacun des informations sur l'efficacité et l'innocuité de ces moyens de protection, la Société de médecine des voyages et la Société française de parasitologie ont initié cette étude qui a pris la forme de « Recommandations de bonne pratique », en suivant le schéma élaboré par la Haute Autorité de santé. Cet ouvrage rassemble ainsi toutes les données pertinentes, validées et mises en forme pour être utilisées non seulement par les personnels de santé (médecins, pharmaciens, infirmiers), mais aussi par les agents touristiques ainsi que par les particuliers pour se protéger des nuisances et des maladies à vecteurs qui constituent de préoccupants problèmes de santé publique
HERschel Observations of Edge-on Spirals (HEROES). I: Far-infrared morphology and dust mass determination
Context. Edge-on spiral galaxies with prominent dust lanes provide us with an
excellent opportunity to study the distribution and properties of the dust
within them. The HEROES project was set up to observe a sample of seven large
edge-on galaxies across various wavelengths for this investigation.
Aims. Within this first paper, we present the Herschel observations and
perform a qualitative and quantitative analysis on them, and we derive some
global properties of the far infrared and submillimetre emission.
Methods. We determine horizontal and vertical profiles from the Herschel
observations of the galaxies in the sample and describe the morphology.
Modified black-body fits to the global fluxes, measured using aperture
photometry, result in dust temperatures and dust masses. The latter values are
compared to those that are derived from radiative transfer models taken from
the literature.
Results. On the whole, our Herschel flux measurements agree well with
archival values. We find that the exponential horizontal dust distribution
model often used in the literature generally provides a good description of the
observed horizontal profiles. Three out of the seven galaxies show signatures
of extended vertical emission at 100 and 160 {\mu}m at the 5{\sigma} level, but
in two of these it is probably due to deviations from an exactly edge-on
orientation. Only for NGC 4013, a galaxy in which vertically extended dust has
already been detected in optical images, we can detect vertically extended
dust, and the derived scaleheight agrees with the value estimated through
radiative transfer modelling. Our analysis hints at a correlation between the
dust scaleheight and its degree of clumpiness, which we infer from the
difference between the dust masses as calculated from modelling of optical data
and from fitting the spectral energy distribution of Herschel datapoints.Comment: 21 pages, 12 figures. Accepted for publication in Astronomy &
Astrophysic
The dust energy balance in the edge-on spiral galaxy NGC 4565
We combine new dust continuum observations of the edge-on spiral galaxy NGC
4565 in all Herschel/SPIRE (250, 350, 500 micron) wavebands, obtained as part
of the Herschel Reference Survey, and a large set of ancillary data (Spitzer,
SDSS, GALEX) to analyze its dust energy balance. We fit a radiative transfer
model for the stars and dust to the optical maps with the fitting algorithm
FitSKIRT. To account for the observed UV and mid-infrared emission, this
initial model was supplemented with both obscured and unobscured star-forming
regions. Even though these star-forming complexes provide an additional heating
source for the dust, the far-infrared/submillimeter emission long wards of 100
micron is underestimated by a factor of 3-4. This inconsistency in the dust
energy budget of NGC 4565 suggests that a sizable fraction (two-thirds) of the
total dust reservoir (Mdust ~ 2.9e+8 Msun) consists of a clumpy distribution
with no associated young stellar sources. The distribution of those dense dust
clouds would be in such a way that they remain unresolved in current
far-infrared/submillimeter observations and hardly comtribute to the
attenuation at optical wavelengths. More than two-thirds of the dust heating in
NGC 4565 is powered by the old stellar population, with localized embedded
sources supplying the remaining dust heating in NGC 4565. The results from this
detailed dust energy balance study in NGC 4565 is consistent with that of
similar analyses of other edge-on spirals.Comment: 16 pages, 7 figures, accepted for publication in MNRA
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