3,994 research outputs found
The ionization mechanism of NGC 185: how to fake a Seyfert galaxy?
NGC 185 is a dwarf spheroidal satellite of the Andromeda galaxy. From
mid-1990s onwards it was revealed that dwarf spheroidals often display a varied
and in some cases complex star formation history. In an optical survey of
bright nearby galaxies, NGC 185 was classified as a Seyfert galaxy based on its
emission line ratios. However, although the emission lines in this object
formally place it in the category of Seyferts, it is probable that this galaxy
does not contain a genuine active nucleus. NGC 185 was not detected in radio
surveys either in 6 or 20 cm, or X-ray observations, which means that the
Seyfert-like line ratios may be produced by stellar processes. In this work, we
try to identify the possible ionization mechanisms for this galaxy. We
discussed the possibility of the line emissions being produced by planetary
nebulae (PNe), using deep spectroscopy observations obtained with GMOS-N, at
Gemini. Although the fluxes of the PNe are high enough to explain the
integrated spectrum, the line ratios are very far from the values for the
Seyfert classification. We then proposed that a mixture of supernova remnants
and PNe could be the source of the ionization, and we show that a composition
of these two objects do mimic Seyfert-like line ratios. We used chemical
evolution models to predict the supernova rates and to support the idea that
these supernova remnants should be present in the galaxy.Comment: 9 pages, 7 figures, accepted for publication in MNRA
A wide angle view of the Sagittarius dwarf Spheroidal Galaxy. I: VIMOS photometry and radial velocities across Sgr dSph major and minor axis
The Sagittarius dwarf Spheroidal Galaxy (Sgr dSph) provides us with a unique
possibility of studying a dwarf galaxy merging event while still in progress.
Due to its low distance (25 kpc), the main body of Sgr dSph covers a vast area
in the sky (roughly 15 x 7 degrees). Available photometric and spectroscopic
studies have concentrated either on the central part of the galaxy or on the
stellar stream, but the overwhelming majority of the galaxy body has never been
probed. The aim of the present study is twofold. On the one hand, to produce
color magnitude diagrams across the extension of Sgr dSph to study its stellar
populations, searching for age and/or composition gradients (or lack thereof).
On the other hand, to derive spectroscopic low-resolution radial velocities for
a subsample of stars to determine membership to Sgr dSph for the purpose of
high resolution spectroscopic follow-up. We used VIMOS-VLT to produce V and I
photometry and spectroscopy on 7 fields across the Sgr dSph minor and major
axis, plus 3 more centered on the associated globular clusters Terzan 7, Terzan
8 and Arp 2. A last field has been centered on M 54, lying in the center of Sgr
dSph. We present photometry for 320,000 stars across the main body of Sgr dSph,
one of the richest, and safely the most wide-angle sampling ever produced for
this fundamental object. We also provide robust memberships for more than one
hundred stars, whose high resolution spectroscopic analysis will be the object
of forthcoming papers. Sgr dSph appears remarkably uniform among the observed
fields. We confirm the presence of a main Sgr dSph population characterized
roughly by the same metallicity of 47 Tuc, but we also found the presence of
multiple populations on the peripheral fields of the galaxy, with a metallicity
spanning from [Fe/H]=-2.3 to a nearly solar value.Comment: 10 pages, 12 figures, accepted for publication in A&
Association between exposure to particulate matter during pregnancy and multidimensional development in schoolâage children: A crossâsectional study in Italy
Air pollutants can potentially affect the development of children. However, data on the effect of exposure to air pollution during pregnancy and developmental outcomes in school children are rare. We investigated the link between prenatal exposure to particulate matters smaller than 10 microns (PM10) and the development of school-age children in multiple domains. Cross-sectional data were collected in Italy between 2013 and 2014. Children aged between 5 and 8 years (n = 1187) were assessed on cognitive, communication, socio-emotional, adaptive, and motor developmental domains using the Developmental Profile 3 questionnaire. The monthly average concentration of PM10 during the entire fetal period was linked to the municipality of residence of the children. The increase in the prenatal PM10 was associated with a decrease in the cognitive score during the second (+13.2 ”g/m3 PM10 increase: â0.30 points; 95%CI: â0.12ââ0.48) and third trimesters of pregnancy (â0.31 points; 95%CI: â0.11ââ0.50). The communicative domain was also negatively influenced by PM10 increases in the second trimester. The development of cognitive and communicative abilities of children was negatively associated with the exposure to PM10 during the period of fetal development, confirming that exposure to air pollution during pregnancy can potentially hinder the development of the brain
Individual based measure of interactive/isolationist degree of infracommunities : towards an assessment of the role of intrinsic and extrinsic factors
The comprehension of the parasite communities structure is a key topic of the parasite ecology pointing the attention to the influence of interaction between co-occuring species.
The idea that communities maybe something more than the result of the current assemblage and that they may reflect the evolutionary process, lead to the proposal of the isolationist/interactive classification of parasite communities. A limit of this vision is that communities are classified, mainly through qualitative assessment, in one of these extreme class missing the continuum occuring in nature. Attempts to develop methods to quantify the isolationist/interactive degree have been addressed mainly at host population level.
Besides, parasite interactions occur within individual hosts and considering the observed heterogeneities of parasites intensities, host individuals may register different isolationism/interaction degree. The analysis at population level may miss to identify the role of intrinsic and extrinsic factors.
We developed a measure at single host level based on the concept of crowding which expresses the mean number of interactions with other parasites each one experiences.
We applied this measure to the parasite community of mountain ruminants which is characterized by high variability between seasons, age and sexes. The mean parasite interaction/isolationism showed high variability mainly related to temporal effect with lesser influence played by host factors
C1âC2 Instability Associated with Periodontoid Inflammatory Tissue Leading to Subarachnoid Hemorrhage: A Case Report and Review of the Literature
Abstract The authors present a case of atlantoaxial instability associated with C1âC2 inflammatory tissue leading to subarachnoid hemorrhage. A 65-year-old male patient arrived in June 2011 to the emergency unit for cervical pain and fever. Imaging studies documented periodontoid pseudotumor at C1âC2 level. Infective disease was suspected; the patient was therefore hospitalized and treated with antibiotics. Subsequent computed tomographic (CT) scans revealed C1âC2 instability. In August, the patient showed acute neurological deterioration and coma. Urgent brain CT revealed a hemorrhagic lesion which caused compression on the medulla oblongata, subarachnoid hemorrhage, and ventricular dilatation. An external ventricular drainage was positioned. Angio-CT and angiography did not show any vascular abnormalities. Cervical magnetic resonance imaging documented a solid tissue lesion between the atlas arch and axis. The lesion was associated with an epidural and subdural hematoma, exerting compression on brainstem. The patient underwent posterior decompression and C1âC2 fusion according to Harms technique in October, with significant clinical improvement. The authors present a case of atlantoaxial instability associated with a periodontoid pseudotumor at C1âC2 level determining dural sac compression. The patient showed an acute neurological deterioration caused by bleeding of the solid component of the cervical lesion. Hemorrhage of the solid component of periodontoid masses linked to atlantoaxial instability has not yet been reported in literature. To the best of our knowledge, this is the first case of C1âC2 instability with periodontoid pseudotumor leading to subarachnoid hemorrhage
Toxoplasma gondii infection in alpine red deer (Cervus elaphus): Its spread and effects on fertility
In contrast to the depth of knowledge on the pathological effects of parasitism in domestic animals, the impact of the vast majority of parasites on wildlife hosts is poorly understood and, besides, information from domestics is rarely usable to disclose the parasites' impact on free-ranging populations' dynamics. Here we use Toxoplasmosis as a study model since, until now, the infection process and the protozoan's effects in natural conditions has received little attention. We analysed 81 sera from red deer (Cervus elaphus) sampled in Italian Alps and through generalized linear models we evaluated (1) the epidemiological factors influencing T. gondii infection dynamics; (2) its impact on female fertility [corrected]. High seroprevalence of T. gondii infection was recorded in yearling (1 year-old; prevalence = 52.4%) and adult (>2 year-old; prevalence = 51.3%) red deer, while calves (<1 year-old) did not contract the infection suggesting horizontal transmission as the main route of infection. The stable prevalence between yearlings and adults and the higher serological titres of younger individuals lead to two alternative infection processes suggesting a difference between age classes or in acquiring the infection or in responding to the pathogen. No associations between T. gondii serological titres and pregnancy status was observed indicating no direct effect on the probability of being pregnant; nevertheless a relation between females' higher serological titres and lower foetal development emerged, suggesting potential effects of the parasite infection on deer reproduction. The results demonstrate high seroprevalence of T. gondii infection in free-ranging red deer and, furthermore, the effect on foetal development suggests the potential impact of the parasite on red deer fertility and thus on its population dynamics
Manganese in dwarf spheroidal galaxies
We provide manganese abundances (corrected for the effect of the hyperfine
structure) for a large number of stars in the dwarf spheroidal galaxies
Sculptor and Fornax, and for a smaller number in the Carina and Sextans dSph
galaxies. Abundances had already been determined for a number of other elements
in these galaxies, including alpha and iron-peak ones, which allowed us to
build [Mn/Fe] and [Mn/alpha] versus [Fe/H] diagrams. The Mn abundances imply
sub-solar [Mn/Fe] ratios for the stars in all four galaxies examined. In
Sculptor, [Mn/Fe] stays roughly constant between [Fe/H]\sim -1.8 and -1.4 and
decreases at higher iron abundance. In Fornax, [Mn/Fe] does not vary in any
significant way with [Fe/H]. The relation between [Mn/alpha] and [Fe/H] for the
dSph galaxies is clearly systematically offset from that for the Milky Way,
which reflects the different star formation histories of the respective
galaxies. The [Mn/alpha] behavior can be interpreted as a result of the
metal-dependent Mn yields of type II and type Ia supernovae. We also computed
chemical evolution models for star formation histories matching those
determined empirically for Sculptor, Fornax, and Carina, and for the Mn yields
of SNe Ia, which were assumed to be either constant or variable with
metallicity. The observed [Mn/Fe] versus [Fe/H] relation in Sculptor, Fornax,
and Carina can be reproduced only by the chemical evolution models that include
a metallicity-dependent Mn yield from the SNe Ia.Comment: 19 pages, 10 figures, accepted for publication in Astronomy &
Astrophysic
Cloud-based automated clinical decision support system for detection and diagnosis of lung cancer in chest CT
Lung cancer is a major cause for cancer-related deaths. The detection of pulmonary cancer in the early stages can highly increase survival rate. Manual delineation of lung nodules by radiologists is a tedious task. We developed a novel computer-aided decision support system for lung nodule detection based on a 3D Deep Convolutional Neural Network (3DDCNN) for assisting the radiologists. Our decision support system provides a second opinion to the radiologists in lung cancer diagnostic decision making. In order to leverage 3-dimensional information from Computed Tomography (CT) scans, we applied median intensity projection and multi-Region Proposal Network (mRPN) for automatic selection of potential regionof-interests. Our Computer Aided Diagnosis (CAD) system has been trained and validated using LUNA16, ANODE09, and LIDC-IDR datasets; the experiments demonstrate the superior performance of our system, attaining sensitivity, specificity, AUROC, accuracy, of 98.4%, 92%, 96% and 98.51% with 2.1 FPs per scan. We integrated cloud computing, trained and validated our Cloud-Based 3DDCNN on the datasets provided by Shanghai Sixth Peopleâs Hospital, as well as LUNA16, ANODE09, and LIDC-IDR. Our system outperformed the state-of-the-art systems and obtained an impressive 98.7% sensitivity at 1.97 FPs per scan. This shows the potentials of deep learning, in combination with cloud computing, for accurate and efficient lung nodule detection via CT imaging, which could help doctors and radiologists in treating lung cancer patients
Genetic variability of Haemonchus contortus (Nematoda: Trichostrongyloidea) in alpine ruminant host species
Genetic variability of the ovine parasite Haemonchus contortus from the Alpine area was investigated using mitochondrial DNA (nd4 gene), internal transcribed spacers 1 and 2 and microsatellites, in order to assess whether cross-transmission between domestic and wild ruminants occurs. The dataset was composed of 78 individual adult male H. contortus collected from chamois (Rupicapra r. rupicapra), roe deer (Capreolus capreolus), alpine ibex (Capra ibex ibex), domestic goat (Capra hircus) and sheep (Ovis aries) from different alpine areas. The data obtained show low host specificity and high genetic variation within H. contortus populations. The analyses indicate the presence of two mitochondrial haplotype clusters among host species and the absence of cryptic parasite species, confirming H. contortus as a generalist nematode and suggesting that parasite transmission between populations of domestic and wild ruminants normally occurs
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