627 research outputs found
The double RGB in M 2: C, N, Sr and Ba abundances
The globular cluster M 2 has a photometrically detected double red giant
branch (RGB) sequence. We investigate here the chemical differences between the
two RGBs in order to gain insight in the star formation history of this
cluster. The low-resolution spectra, covering the blue spectral range, were
collected with the MODS spectrograph on the LBT, and analyzed via spectrum
synthesis technique. The high quality of the spectra allows us to measure C, N,
Ba, and Sr abundances relative to iron for 15 RGB stars distributed along the
two sequences. We add to the MODS sample C and N measurements for 35 additional
stars belonging to the blue RGB sequence, presented in Lardo et al. (2012). We
find a clear separation between the two groups of stars in s-process elements
as well as C and N content. Both groups display a C-N anti-correlation and the
red RGB stars are on average richer in C and N with respect to the blue RGB.
Our results reinforce the suggestion that M2 belongs to the family of globular
clusters with complex star formation history, together with Omega Cen, NGC
1851, and M 22.Comment: 11 pages, 8 figures. Accepted for publication in MNRA
Explosion of a massive, He-rich star at z=0.16
We present spectroscopic and photometric data of the peculiar SN 2001gh,
discovered by the 'Southern inTermediate Redshift ESO Supernova Search'
(STRESS) at a redshift z=0.16. SN 2001gh has relatively high luminosity at
maximum (M_B = -18.55 mag), while the light curve shows a broad peak. An
early-time spectrum shows an almost featureless, blue continuum with a few weak
and shallow P-Cygni lines that we attribute to HeI. HeI lines remain the only
spectral features visible in a subsequent spectrum, obtained one month later. A
remarkable property of SN 2001gh is the lack of significant spectral evolution
over the temporal window of nearly one month separating the two spectra. In
order to explain the properties of SN 2001gh, three powering mechanism are
explored, including radioactive decays of a moderately large amount of 56Ni,
magnetar spin-down, and interaction of SN ejecta with circumstellar medium. We
favour the latter scenario, with a SN Ib wrapped in a dense, circumstellar
shell. The fact that no models provide an excellent fit with observations,
confirms the troublesome interpretation of the nature of SN 2001gh. A rate
estimate for SN 2001gh-like event is also provided, confirming the intrinsic
rarity of these objects.Comment: 11 pages, 8 figures, 3 tables. Accepted by MNRA
The Gaia spectrophotometric standard stars survey -II. Instrumental effects of six ground-based observing campaigns
The Gaia SpectroPhotometric Standard Stars (SPSS) survey started in 2006, it
was awarded almost 450 observing nights, and accumulated almost 100,000 raw
data frames, with both photometric and spectroscopic observations. Such large
observational effort requires careful, homogeneous, and automated data
reduction and quality control procedures. In this paper, we quantitatively
evaluate instrumental effects that might have a significant (i.e.,1%)
impact on the Gaia SPSS flux calibration. The measurements involve six
different instruments, monitored over the eight years of observations dedicated
to the Gaia flux standards campaigns: DOLORES@TNG in La Palma, EFOSC2@NTT and
ROSS@REM in La Silla, [email protected] in Calar Alto, BFOSC@Cassini in Loiano, and
[email protected] in San Pedro Martir. We examine and quantitatively evaluate the
following effects: CCD linearity and shutter times, calibration frames
stability, lamp flexures, second order contamination, light polarization, and
fringing. We present methods to correct for the relevant effects, which can be
applied to a wide range of observational projects at similar instruments.Comment: 16 pages, 13 figures, accepted for publication in Astron. Nach
An Intermediate Redshift Supernova Search at ESO: Reduction Tools and Efficiency Tests
We present the reduction and archiving tools developed for our search for
supernovae at intermediate redshifts at ESO as well as the efficiency tests
performed. The data reduction recipes developed for the SN candidates selection
are described. All the variable sources detected are stored using a MySQL
database which enables the identification of previously detected variable
sources during past observational runs. Finally, experiments performed with
artificial stars have shown that seeing plays a crucial role for the limiting
magnitude of detection. Crucial is also the detection threshold used by
Sextractor.Comment: Poster presented at the ESO/MPA/MPE Workshop "From Twilight to
Highlight, The Physics of Supernovae", Garching, Jul 29-31, 2002, to be
published in the Conference Proceeding
Lie for me: How empathy, alexithymia and emotional intelligence influence the ability to conform facial expression to a prosocial untrue verbal message
The aim of this work was to investigate the association between emotional variables (empathy, emotional intelligence, alexithymia) and lying skills. The hypothesis was that a higher emotional competence was associated to a better ability to lie. In an experimental setting, thirty-four participants were videotaped in two separate session: The first in which they were telling the truth and the second in which, motivated by a social and empathetical intention, they were lying about some emotionally arousing images they viewed. Moreover, all participant filled three self-report questionnaires: The 20-Item Toronto Alexithymia Scale, The Interpersonal Reactivity Index and The Trait Emotional Intelligence Questionnaire Short Form. The coding of facial responses was carried out using the Facial Action Coding System. The findings suggested that emotional competence is associated with the ability to lie and to conform facial expression to a prosocial untrue statement. Conversely, individuals with higher levels of alexithymia and lower emotional ability manifested more marker of discomfort as facial manipulators in lying, other than inconsistencies in verbal/nonverbal messages even telling the truth, probably due to their difficulties to identify and express emotions
The diversity of Type Ia Supernovae: evidence for systematics?
The photometric and spectroscopic properties of 26 well observed Type Ia
Supernovae (SNeIa) were analyzed with the aim to explore SNIa diversity. The
sample includes (Branch-)normal SNe as well as extreme events like SNe 1991T
and 1991bg, while the truly peculiar SNIa, SN2000cx and SN2002cx are not
included in our sample . A statistical treatment reveals the existence of three
different groups. The first group (FAINT) consists of faint SNeIa similar to
SN1991bg, with low expansion velocities and rapid evolution of SiII velocity. A
second group consists of ``normal'' SNeIa, also with high temporal velocity
gradient (HVG), but with brighter mean absolute magnitude =-19.3 and
higher expansion velocities than the FAINT SNe. The third group includes both
``normal'' and SN1991T-like SNeIa: these SNe populate a narrow strip in the
SiII velocity evolution plot, with a small velocity gradient (SVG), but have
absolute magnitudes similar to HVGs. While the FAINT and HVG SNeIa together
seem to define a relation between RSi(II) and Dm15(B), the SVG ones either do
not conform with that relation or define a new, looser one. The RSi(II)
pre-maximum evolution of HVGs is strikingly different from that of SVGs. The
impact of this evidence on the understanding of SNIa diversity, in terms of
explosion mechanisms, degree of ejecta mixing, and ejecta-CSM interaction, is
discussed.Comment: 9 pages, 3 figures, accepted for publication to ApJ; few referee's
comments adde
Endometrioid Cancer Associated With Endometriosis: From the Seed and Soil Theory to Clinical Practice
Endometriosis is a benign condition characterized by the presence of ectopic endometrial tissue. It is still debated whether endometriosis is a disease that can predispose to the pathogenesis of endometrial cancer outside the uterus. Deficiencies in mismatch repair (MMR) genes are a known risk factor for developing endometrioid cancer. Starting from two cases of patients with abnormal MMR endometrioid carcinoma of the uterus and synchronous endometrioid carcinoma in non-ovarian and ovarian endometriosis, we performed a somatic mutation profile and phylogenetic analysis of the lesions in order to identify if they were metastasis or primary de novo tumors. In the first case, we identified de novo activating mutations in PIK3CA and KRAS in endometrioid cancer lesions but not in endometriosis. Although the acquisition of a de novo mutation in ESR1 and a decrease in mutant allele fraction (MAF) from the endometrial tumor to the localizations in the endometriosis lesions, the clonal relationship was confirmed by the limited number of heteroplasmic mutations in D-loop mitochondrial DNA region. In the other case, the clonal behavior was demonstrated by the overlap of MAF at each site. Our data support the hypothesis of a retrograde dissemination of tumor cells, moving from the primary carcinoma in the endometrium to ectopic sites of endometriosis where localizations of tumor arise
Gaia data release 1: Principles of the photometric calibration of the G band
Context. Gaia is an ESA cornerstone mission launched on 19 December 2013
aiming to obtain the most complete and precise 3D map of our Galaxy by
observing more than one billion sources. This paper is part of a series of
documents explaining the data processing and its results for Gaia Data Release
1, focussing on the G band photometry. Aims. This paper describes the
calibration model of the Gaia photometric passband for Gaia Data Release 1.
Methods. The overall principle of splitting the process into internal and
external calibrations is outlined. In the internal calibration, a
self-consistent photometric system is generated. Then, the external calibration
provides the link to the absolute photometric flux scales. Results. The Gaia
photometric calibration pipeline explained here was applied to the first data
release with good results. Details are given of the various calibration
elements including the mathematical formulation of the models used and of the
extraction and preparation of the required input parameters (e.g. colour
terms). The external calibration in this first release provides the absolute
zero point and photometric transformations from the Gaia G passband to other
common photometric systems. Conclusions. This paper describes the photometric
calibration implemented for the first Gaia data release and the instrumental
effects taken into account. For this first release no aperture losses,
radiation damage, and other second-order effects have not yet been implemented
in the calibration.Comment: 15 pages, 16 figures, Gaia data release 1 documentation special
volum
Optimization clustering techniques on register unemployment data
An important strategy for data classification consists in organising data
points in clusters. The k-means is a traditional optimisation method applied to
cluster data points. Using a labour market database, aiming the segmentation of this
market taking into account the heterogeneity resulting from different unemployment
characteristics observed along the Portuguese geographical space, we suggest the
application of an alternative method based on the computation of the dominant
eigenvalue of a matrix related with the distance among data points. This approach
presents results consistent with the results obtained by the k-means.info:eu-repo/semantics/publishedVersio
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