The chemical evolution of Manganese in different stellar systems

Aims. To model the chemical evolution of manganese relative to iron in three different stellar systems: the solar neighbourhood, the Galactic bulge and the Sagittarius dwarf spheroidal galaxy, and compare our results with the recent and homogeneous observational data. Methods. We adopt three chemical evolution models well able to reproduce the main properties of the solar vicinity, the galactic Bulge and the Sagittarius dwarf spheroidal. Then, we compare different stellar yields in order to identify the best set to match the observational data in these systems. Results. We compute the evolution of manganese in the three systems and we find that in order to reproduce simultaneously the [Mn/Fe] versus [Fe/H] in the Galactic bulge, the solar neighbourhood and Sagittarius, the type Ia SN Mn yield must be metallicity-dependent. Conclusions. We conclude that the different histories of star formation in the three systems are not enough to reproduce the different behaviour of the [Mn/Fe] ratio, unlike the situation for [alpha/Fe]; rather, it is necessary to invoke metallicity-dependent type Ia SN Mn yields, as originally suggested by McWilliam, Rich & Smecker-Hane in 2003.Comment: 9 pages, 3 figures, submitted to A&

Rare decays at the LHCb experiment

Rare flavour-changing neutral-current (FCNC) decays of beauty and charm quarks, lepton flavour- and lepton-number–violating decays can provide a powerful probe for as yet unobserved virtual particles. Recent results on these topics from the LHCb experiment are reviewed. Particular attention is paid to the angular distribution of the B0 → K ∗0μ+μ− decay, where a measurement performed by LHCb shows a local discrepancy of 3.7 standard deviations with respect to the SM prediction. Using the decay B+ → K+π+π−γ, LHCb have also been able to demonstrate the polarisation of photons produced in b → s transitions. An update for the studies dedicated to decays τ+ → μ+μ−μ+ and B0(s)→ μ ± e ∓ and to the on-shell Majorana neutrinos coupling to muons in the B+ → π−μ+μ+ decay channel are also presented

Search for the rare decays B0s → μ+μ− and B0 → μ+μ− with the LHCb experiment

A search for the decays B0s → μ+μ− and B0 → μ+μ− is performed with about 37 pb−1 of pp collisions at √s = 7TeV collected by the LHCb experiment at the Large Hadron Collider at CERN. The observed numbers of events are consistent with the background expectations. The resulting upper limits on the branching ratios are BR(B0s → μ+μ−) < 5.6 × 10−8 and BR(B0 → μ+μ−) < 1.5 × 10−8 at 95% confidence level

Chemical evolution of the bulge of M31: predictions about abundance ratios

We aim at reproducing the chemical evolution of the bulge of M31 by means of a detailed chemical evolution model, including radial gas flows coming from the disk. We study the impact of the initial mass function, the star formation rate and the time scale for bulge formation on the metallicity distribution function of stars. We compute several models of chemical evolution using the metallicity distribution of dwarf stars as an observational constraint for the bulge of M31. Then, by means of the model which best reproduces the metallicity distribution function, we predict the [X/Fe] vs. [Fe/H] relations for several chemical elements (O, Mg, Si, Ca, C, N). Our best model for the bulge of M31 is obtained by means of a robust statistical method and assumes a Salpeter initial mass function, a Schmidt-Kennicutt law for star formation with an exponent k=1.5, an efficiency of star formation of $\sim 15\pm 0.27\, Gyr^{-1}$, and an infall timescale of $\sim 0.10\pm 0.03$Gyr. Our results suggest that the bulge of M31 formed very quickly by means of an intense star formation rate and an initial mass function flatter than in the solar vicinity but similar to that inferred for the Milky Way bulge. The [$\alpha$/Fe] ratios in the stars of the bulge of M31 should be high for most of the [Fe/H] range, as is observed in the Milky Way bulge. These predictions await future data to be proven.Comment: Accepted for publication by MNRA

Detailed Chemical Evolution of Carina and Sagittarius Dwarf Spheroidal Galaxies

In order to verify the effects of the most recent data on the evolution of Carina and Sagittarius Dwarf Spheroidal Galaxies (dSph) and to set tight constraints on the main parameters of chemical evolution models, we study in detail the chemical evolution of these galaxies through comparisons between the new data and the predictions of a model, already tested to reproduce the main observational constraints in dSphs. Several abundance ratios, such as [$\alpha$/Fe], [Ba/Fe] and [Eu/Fe], and the metallicity distribution of stars are compared to the predictions of our models adopting the observationally derived star formation histories in these galaxies. These new comparisons confirm our previously suggested scenario for the evolution of these galaxies, and allow us to better fix the star formation and wind parameters. In particular, for Carina the comparisons indicate that the best efficiency of star formation is $\nu = 0.15 Gyr^{-1}$, that the best wind efficiency parameter is $w_i$ = 5 (the wind rate is five times stronger than the star formation rate), and that the star formation history, which produces the best fit to the observed metallicity distribution of stars is characterized by several episodes of activity. In the case of Sagittarius our results suggest that $\nu=3 Gyr^{-1}$ and $w_i=9$, again in agreement with our previous work. Finally, we show new predictions for [N/Fe] and [C/Fe] ratios for the two galaxies suggesting a scenario for Sagittarius very similar to the one of the solar vicinity in the Milky Way, except for a slight decrease of [N/Fe] ratio at high metallicities due to the galactic wind. For Carina we predict a larger [N/Fe] ratio at low metallicities, reflecting the lower star formation efficiency of this galaxy relative to Sagittarius and the Milky Way.Comment: 11 pages, 7 figures, accepted for publication in Asttronomy & Astrophysic

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

Calibration Strategy and Efficiency measurement of the Muon Identification procedure at LHCb

We present a strategy for calibrating with data the LHCb muon identification procedure and for extracting in-situ the performance. Two main calibration samples are used: the inclusive $J\psi \to \mu\mu$ decay as a source of muons and the $\lambda(1115.7)\to p\pi$ decay as a source of hadrons decaying and non-decaying in flight. For each of them we describe the selection, the expected purity and the rates for different running scenarios. The distributions extracted from calibration samples are compared with those obtained from a generic b-inclusive sample. An estimate of the precision that can be reached in the evaluation of the muon identification efficiency and misidentification rate is given as a function of the collected statistics

Inspiratory muscle training and its effect on indices of physiological and perceived stress during incremental walking exercise in normobaric hypoxia

This study evaluated the effects of inspiratory muscle training (IMT) on inspiratory muscle fatigue (IMF) and physiological and perceptual responses during trekking-specific exercise. An 8-week IMT program was completed by 21 males (age 32.4 ± 9.61 years, VO2peak 58.8 ± 6.75 mL/kg/min) randomised within matched pairs to either the IMT group (n = 11) or the placebo group [(P), n = 9]. Twice daily, participants completed 30 (IMT) or 60 (P) inspiratory efforts using a Powerbreathe initially set at a resistance of 50% (IMT) or used at 15% (P) of maximal inspiratory pressure (MIP) throughout. A loaded (12.5 kg) 39-minute incremental walking protocol (3–5 km/hour and 1–15% gradient) was completed in normobaric hypoxia (PIO2 = 110 mmHg, 3000 m) before and after training. MIP increased from 164 to 188 cmH2O (18%) and from 161 to 171 cmH2O (6%) in the IMT and P groups (P = 0.02). The 95% CI for IMT showed a significant improvement in MIP (5.21±43.33 cmH2O), but not for P. IMF during exercise (MIP) was*5%, showing no training effect for either IMT or P (P = 0.23). Rating of perceived exertion (RPE) was consistently reduced (*1) throughout exercise following training for IMT, but not for P (P = 0.03). The mean blood lactate concentration during exercise was significantly reduced by 0.26 and 0.15 mmol/L in IMT and P (P = 0.00), with no differences between groups (P = 0.34). Rating of dyspnoea during exercise decreased (*0.4) following IMT but increased (*0.3) following P (P = 0.01). IMT may attenuate the increased physiological and perceived exercise stress experienced during normobaric hypoxia, which may benefit moderate altitude expedition

The Effect of Probabilistic Context on Implicit Temporal Expectations in Down Syndrome

One of the most important sources of predictability that human beings can exploit to create an internal representation of the external environment is the ability to implicitly build up subjective statistics of events\u2019 temporal structure and, consequently, use this knowledge to prepare for future actions. Stimulus expectancy can be subjectively shaped by hierarchically nested sources of prediction, capitalizing on either local or global probabilistic rules. In order to better understand the nature of local-global proactive motor control in Down Syndrome, in the present study a group of participants with Down Syndrome (DS group; n = 28; mean age 29.5 \ub1 13 years; range 10\u201354) and a group of typically developing participants matched by either gender or mental age (TD-MA group; n = 28; 5.6 \ub1 1 years; range 4\u20138) were administered a novel motor preparation task, defined as the Dynamic Temporal Prediction (DTP) task. In the DTP, the temporal preparation to imperative stimuli is implicitly shaped by the local increase of expectancy. This is manipulated trial-by-trial as a function of the preparatory foreperiod interval (Stimulus-Onset Asynchrony or SOA). In addition, temporal preparation can be also implicitly adjusted as a function of global predictive context, so that a block-wise SOA-distribution bias toward a given preparatory interval might determine a high-order source of expectancy, with functional consequences on proactive motor control adjustment. Results showed that in both groups motor preparation was biased by temporal expectancy when this was locally manipulated within-trials. By contrast, only the TD-MA group was sensitive to global rule changes: only in this cohort was behavioral performance overall impacted by the SOA probabilistic distribution manipulated between-blocks. The evidence of a local-global dissociation in DS suggests that the use of flexible cognitive mechanisms to implicitly extract high-order probabilistic rules in order to build-up an internal model of the temporal properties of events is disrupted in this developmental disorder. Moreover, since the content of the information to be processed in the DTP task was neither verbal nor spatial, we suggest that atypical global processing in Down Syndrome is a domain-general rather than specific aspect characterizing the cognitive profile of this population