Galaxy gas flows inferred from a detailed, spatially resolved metal budget

We use the most extensive integral field spectroscopic map of a local galaxy, NGC 628, combined with gas and stellar mass surface density maps, to study the distribution of metals in this galaxy out to 3 effective radii ($\rm R_e$). At each galactocentric distance, we compute the metal budget and thus constrain the mass of metals lost. We find that in the disc about 50% of the metals have been lost throughout the lifetime of the galaxy. The fraction of metals lost is higher in the bulge ($\sim$70%) and decreases towards the outer disc ($\rm \sim 3 \ R_e$). In contrast to studies based on the gas kinematics, which are only sensitive to ongoing outflow events, our metal budget analysis enables us to infer the average outflow rate during the galaxy lifetime. By using simple physically motivated models of chemical evolution we can fit the observed metal budget at most radii with an average outflow loading factor of order unity, thus clearly demonstrating the importance of outflows in the evolution of disc galaxies of this mass range ($\rm log(M_\star/M_\odot) \sim 10)$. The observed gas phase metallicity is higher than expected from the metal budget and suggests late-time accretion of enriched gas, likely raining onto the disc from the metal-enriched halo.FB acknowledges support from the United Kingdom Science and Technology Facilities Council. This work makes use of THINGS (‘The Nearby Galaxy Survey’, Walter et al. 2008), HERACLES (the ‘HERA CO line Extragalactic Survey’, Leroy et al. 2009) and PINGS (the ‘PPAK IFS Nearby Galaxy Survey’, Rosales-Ortega et al. 2010). We acknowledge the contribution from the referee in improving the content and the clarity of the paper. We thank Fiorenzo Vincenzo and Francesca Matteucci for their invaluable help in interpreting the vast literature on chemical abundance modelling and nucleosynthetic yields. We also thank Ying-jie Peng for support and discussion on development of his chemical evolution models. We wish to thank Fabian Rosales-Ortega for kindly sharing the PINGS data on NGC 628 and for his encouragement and feedback on the early stages of this work. We thank Matt Auger for useful discussions and healthy skepticism and the participants to the MPIA summer workshop ‘A 3D view on galaxies evolution: from statistics to physics’ for insightful comments.This is the author accepted manuscript. The final version is available from Oxford University Press via http://dx.doi.org/10.1093/mnras/stv233

Nitrogen and oxygen abundances in the Local Universe

We present chemical evolution models aimed at reproducing the observed (N/O) vs. (O/H) abundance pattern of star forming galaxies in the Local Universe. We derive gas-phase abundances from SDSS spectroscopy and a complementary sample of low-metallicity dwarf galaxies, making use of a consistent set of abundance calibrations. This collection of data clearly confirms the existence of a plateau in the (N/O) ratio at very low metallicity, followed by an increase of this ratio up to high values as the metallicity increases. This trend can be interpreted as due to two main sources of nitrogen in galaxies: i) massive stars, which produce small amounts of pure primary nitrogen and are responsible for the (N/O) ratio in the low metallicity plateau; ii) low- and intermediate-mass stars, which produce both secondary and primary nitrogen and enrich the interstellar medium with a time delay relative to massive stars, and cause the increase of the (N/O) ratio. We find that the length of the low-metallicity plateau is almost solely determined by the star formation efficiency, which regulates the rate of oxygen production by massive stars. We show that, to reproduce the high observed (N/O) ratios at high (O/H), as well as the right slope of the (N/O) vs. (O/H) curve, a differential galactic wind - where oxygen is assumed to be lost more easily than nitrogen - is necessary. No existing set of stellar yields can reproduce the observed trend without assuming differential galactic winds. Finally, considering the current best set of stellar yields, a bottom-heavy initial mass function is favoured to reproduce the data.FV thanks the Cavendish Astrophysics Group at the University of Cambridge for kindly supporting his visit during 2014 September. FB acknowledges funding from the United Kingdom Science and Technology Facilities Council (STFC). RM acknowledges funding from the United Kingdom STFC through grant ST/M001172/1. FM acknowledges financial support from PRIN-MIUR 2010-2011 project ‘The Chemical and Dynamical Evolution of the Milky Way and Local Group Galaxies’, prot. 2010LY5N2T.This is the final version of the article. It first appeared from Oxford University Press via http://dx.doi.org/10.1093/mnras/stw53

Analytical Modeling of a New Compliant Microsystem for Atherectomy Operations

This work offers a new alternative tool for atherectomy operations, with the purpose of minimizing the risks for the patients and maximizing the number of clinical cases for which the system can be used, thanks to the possibility of scaling its size down to lumen reduced to a few tenths of mm. The development of this microsystem has presented a certain theoretical work during the kinematic synthesis and the design stages. In the first stage a new multi-loop mechanism with a Stephenson’s kinematic chain (KC) was found and then adopted as the so-called pseudo-rigid body mechanism (PRBM). Analytical modeling was necessary to verify the synthesis requirements. In the second stage, the joint replacement method was applied to the PRBM to obtain a corresponding and equivalent compliant mechanism with lumped compliance. The latter presents two loops and six elastic joints and so the evaluation of the microsystem mechanical advantage (MA) had to be calculated by taking into account the accumulation of elastic energy in the elastic joints. Hence, a new closed form expression of the microsystem MA was found with a method that presents some new aspects in the approach. The results obtained with Finite Element Analysis (FEA) were compared to those obtained with the analytical model. Finally, it is worth noting that a microsystem prototype can be fabricated by using MEMS Technology classical methods, while the microsystem packaging could be a further development for the present investigation

Discovery of periodic dips in the brightest hard X-ray source of M31 with EXTraS

We performed a search for eclipsing and dipping sources in the archive of the EXTraS project - a systematic characterization of the temporal behaviour of XMM-Newton point sources. We discovered dips in the X-ray light curve of 3XMM J004232.1+411314, which has been recently associated with the hard X-ray source dominating the emission of M31. A systematic analysis of XMM-Newton observations revealed 13 dips in 40 observations (total exposure time $\sim$0.8 Ms). Among them, four observations show two dips, separated by $\sim$4.01 hr. Dip depths and durations are variable. The dips occur only during low-luminosity states (L$_{0.2-12}<1\times10^{38}$ erg s$^{-1}$), while the source reaches L$_{0.2-12}\sim2.8\times10^{38}$ erg s$^{-1}$. We propose this system to be a new dipping Low-Mass X-ray Binary in M31 seen at high inclination (60$^{\circ}$-80$^{\circ}$), the observed dipping periodicity is the orbital period of the system. A blue HST source within the Chandra error circle is the most likely optical counterpart of the accretion disk. The high luminosity of the system makes it the most luminous dipper known to date.Comment: 11 pages, 2 figures, 5 tables, accepted for publication in ApJ

Nuclear data uncertainty quantification on PWR spent nuclear fuel as a function of burnup

Nuclear data uncertainty analysis on the spent nuclear fuel inventory was performed on the Takahama-3 NT3G23 assembly, where the sample SF95-4 was irradiated up to a burnup of approximately 36 GWd/ t according to the SFCOMPO benchmark. The cross-section covariance matrices stored in the ENDF/B-VIII.0, JEFF-3.3 and JENDL-4.0u evaluated nuclear data libraries were propagated with the stochastic sampling algorithms implemented in the SANDY code. A comparison of the concentration uncertainty differences obtained using data from the three libraries is reported. Similarities were found with the fuel composition uncertainty results obtained for the Calvert Cliffs MKP109 sample P SFCOMPO benchmark. Such a similarity was also found when comparing concentration uncertainties along the sample irradiation. Therefore, the main contributors to the concentration uncertainty of a number of nuclides were identified at different burnup levels in the two samples. To complement the similarity analysis, a correlation study of the concentration distributions predicted by the two models was performed. The reported results hint a dominance of the common uncertainty propagation mechanisms over the model differences in the determination of concentration uncertainty

Widespread star formation inside galactic outflows

Several models have predicted that stars could form inside galactic outflows and that this would be a new major mode of galaxy evolution. Observations of galactic outflows have revealed that they host large amounts of dense and clumpy molecular gas, which provide conditions suitable for star formation. We have investigated the properties of the outflows in a large sample of galaxies by exploiting the integral field spectroscopic data of the large MaNGA-SDSS4 galaxy survey. We find that star formation occurs inside at least half of the galactic outflows in our sample. We also show that even if star formation is prominent inside many other galactic outflows, this may have not been revealed as the diagnostics are easily dominated by the presence of even faint AGN and shocks. If very massive outflows typical of distant galaxies and quasars follow the same scaling relations observed locally, then the star formation inside high-z outflows can be up to several 100 Msun/yr and could contribute substantially to the early formation of the spheroidal component of galaxies. Star formation in outflows can also potentially contribute to establishing the scaling relations between black holes and their host spheroids. Moreover, supernovae exploding on large orbits can chemically enrich in-situ and heat the circumgalactic and intergalactic medium. Finally, young stars ejected on large orbits may also contribute to the reionization of the Universe

Effect of manure application timing on roots, canopy and must quality in Vitis vinifera 'Merlot': a case study in Italy, North-East

The maintenance and improvement of soil fertility are among the most important management practices in viticulture. The system efficiency fertilization (SEF) which is a new concept based on a maximum utilization of organic fertilizers (i.e., manure) has become very important, especially within the organic viticulture sector, since other fertilizers are not allowed. The aim of this study was to determine the effect of different manure application timing on the root, shoot, and the grapevine yield, accumulation, and quality of biochemical compounds in the grape must since the timing effect was not previously investigated. The study was carried out on 'Merlot' variety organically cultivated, whose production aims at obtaining high-quality red wines. Three treatments were applied: NT (Non-Treated), T1 (Treated1- manure applied in late October) and T2 (Treated2 - manure applied in late February). After two study-years, the undertaken research has shown positive influences of soil manure application on the canopy features (T1), yield, and yield components (T2), along with a major accumulation of the primary metabolites (T2) (soluble solid, carbohydrates, chlorophyll). Yet, the secondary metabolites (polyphenols and anthocyanins) were promoted in the grape must at harvest time, especially when the manure was applied in late October (T2). Considering the benefits of manure application in the T2, after two study years, this timing is recommended in order to improve 'Merlot' grapes for high-quality red wine production