715 research outputs found

    The double RGB in M 2: C, N, Sr and Ba abundances

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    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

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    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

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    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

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    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

    Bond Returns and Market Expectations

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    The Gaia spectrophotometric standard stars survey -II. Instrumental effects of six ground-based observing campaigns

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    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.,≥\geq1%) 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

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    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

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    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

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    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
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