715 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
Interspecific aggression and food competition between the global invader Palaemon macrodactylus and the native Palaemon elegans
The impact of invasive alien species on native communities can act at different levels both
by affecting the ecosystem’s structure (i.e., mainly in the case of vegetation) and through direct
interactions (i.e., competition for food or space). Behavioral studies under controlled conditions can
provide relevant information on both the invasive potential of alien species and the potential impact
of the invaders on the local native species. In the laboratory, the competition for food resources
between the invasive oriental shrimp Palaemon macrodactylus, Rathbun, 1902, and the Mediterranean
native shrimp Palaemon elegans, Rathke, 1836, was analyzed. These species are typical residents of
coastal transitional and estuarine waters, so the experiments were carried out using two salinity
conditions that characterize the coastal lagoon of Venice. Although at both salinity treatments the
alien species tended to be more aggressive than the native one, significant differences between the
two species were mainly observed at a salinity of 30. In particular, at a salinity of 30, P. macrodactylus
spent more time attending to the food source than the native species. The results are discussed in
light of the potential inter-specific competition between the two species within the conditions of the
Venice lagoon
Supernova search at intermediate z. I. Spectroscopic analysis
We study 8 supernovae discovered as part of the International Time Programme
(ITP) project ``Omega and Lambda from Supernovae and the Physics of Supernova
Explosions'' at the European Northern Observatory (ENO). The goal of the
project is to increase the sample of intermediate redshift (0.1<z<0.4) SNe Ia
for testing properties of SNe Ia along z and for enlarging the sample in the
Hubble diagram up to large z.Comment: 2 pages, 2 figures, 1 table, to appear in ``1604-2004: Supernovae as
Cosmological Lighthouses'', (extended text upon request
Field emission properties of as-grown multiwalled carbon nanotube films
Multiwalled carbon nanotubes have been produced by ethylene catalytic
chemical vapor deposition and used to fabricate thick and dense freestanding
films ("buckypapers") by membrane filtering. Field emission properties of
buckypapers have been locally studied by means of high vacuum atomic force
microscopy with a standard metallic cantilever used as anode to collect
electrons emitted from the sample. Buckypapers showed an interesting linear
dependence in the Fowler-Nordheim plots demonstrating their suitability as
emitters. By precisely tuning the tip-sample distance in the submicron region
we found out that the field enhancement factor is not affected by distance
variations up to 2um. Finally, the study of current stability showed that the
field emission current with intensity of about 3,3*10-5A remains remarkably
stable (within 5% fluctuations) for several hours.Comment: 18 pages, 5 figure
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
Supernova search at intermediate z. II. Host galaxy morphology
We discuss the host galaxy morphology of the 8 SNe discovered as a part of
the International Time Programme (ITP) project ``Omega and Lambda from
Supernovae, and the Physics of Supernovae Explosions'' at the European Northern
Observatory (ENO). Identification of the SN host galaxy types was done
exploiting both imaging and spectroscopy. A peculiar SNIa at z= 0.033 is found
in a spiral galaxy, as most other SNeIa with z between 0.1 and 0.4. A complete
account of these studies will be given elsewhere.Comment: 2 pages, 2 figures, 1 table, to appear in ``1604-2004: Supernovae as
Cosmological Lighthouses'', (extended text upon request
Supernova search at intermediate z. III. Expansion velocities of the ejecta
We discuss the expansion velocities of different elements in the ejecta of
the intermediate-z SNe Ia discovered as a part of the International Time
Programme (ITP) project ``Omega and Lambda from Supernovae and the Physics of
Supernova Explosions'' at the European Northern Observatory (ENO). The
expansion velocities measured for each normal SNIa are found to be within the
typical velocity dispersion for their epoch. Meanwhile, the subluminous SN
2002lk SiII expansion velocity is significantly higher than that of SN 1991bg
shortly after maximum. The observed phase was younger in SN2002lk than in the
local subluminous SNIa SN1991bg.Comment: 2 pages, 1 figure, 1 table, to appear in ``1604-2004: Supernovae as
Cosmological Lighthouses'', (extended text upon request
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
- …