Abundance analysis of red clump stars in the old, inner disc, open cluster NGC 4337: a twin of NGC 752?

Open star clusters older than ~ 1 Gyr are rare in the inner Galactic disc. Still, they are objects that hold crucial information for probing the chemical evolution of these regions of the Milky Way. We aim at increasing the number of old open clusters in the inner disc for which high-resolution metal abundances are available. Here we report on NGC 4337, which was recently discovered to be an old, inner disc open cluster. We present the very first high-resolution spectroscopy of seven clump stars that are all cluster members. We performed a detailed abundance analysis for them. We find that NGC 4337 is marginally more metal-rich than the Sun, with [Fe/H]=+0.12$\pm$0.05. The abundance ratios of $\alpha$-elements are generally solar. At odds with recent studies on intermediate-age and old open clusters in the Galactic disc, Ba is under-abundant in NGC 4337 compared with the Sun. Our analysis of the iron-peak elements (Cr and Ni) does not reveal anything anomalous. Based on these results, we estimate the cluster age to be 1.6$^{+0.1}_{-0.1}$ Gyr, and derive a reddening E(B-V)=0.23$\pm$0.05, and an apparent distance modulus $(m-M)_{V}=12.80\pm0.15$. Its distance to the Galactic centre is 7.6 kpc. With this distance and metallicity, NGC 4337 fits the metallicity gradient for the inner Galactic disc fairly well. The age and metallicity we measured make NGC 4337 a twin of the well-known old open cluster NGC 752. The red clumps of these two clusters bear an amazing resemblance. But the main sequence of NGC 752 is significantly more depleted in stars than that of NGC 4337. This would mean that NGC 752 is in a much more advanced dynamical stage, being on the verge of dissolving into the general Galactic field. Our results make NGC 4337 an extremely interesting object for further studies of stellar evolution in the critical turn-off mass range 1.1-1.4 solar masses.Comment: 7 pages, 8 eps figures, in press in Astronomy and Astrophysics. arXiv admin note: text overlap with arXiv:1401.156

Updated properties of the old open cluster Melotte 66: Searching for multiple stellar populations

Multiple generations of stars are routinely encountered in globular clusters but no convincing evidence has been found in Galactic open clusters to date. In this paper we use new photometric and spectroscopic data to search for multiple stellar population signatures in the old, massive open cluster, Melotte~66. The cluster is known to have a red giant branch wide in color, which could be an indication of metallicity spread. Also the main sequence is wider than what is expected from photometric errors only. This evidence might be associated with either differential reddening or binaries. Both hypothesis have, however, to be evaluated in detail before recurring to the presence of multiple stellar populations. New, high-quality, CCD UBVI photometry have been acquired to this aim with high-resolution spectroscopy of seven clump stars, that are complemented with literature data. Our photometric study confirms that the width of the main sequence close to the turn off point is entirely accounted for by binary stars and differential reddening, with no need to advocate more sofisticated scenarios, such as metallicity spread or multiple main sequences. By constructing synthetic color-magnitude diagrams, we infer that the binary fraction has to be as large as 30$$ and their mass ratio in the range 0.6-1.0. As a by-product of our simulations, we provide new estimates of the cluster fundamental parameters. We measure a reddening E(B-V)=0.15$\pm$0.02, and confirm the presence of a marginal differential reddening. The distance to the cluster is $4.7^{+0.2}_{-0.1}$kpc and the age is 3.4$\pm$0.3 Gyr, which is somewhat younger and better constrained than previous estimates. Our detailed abundance analysis reveals that, overall, Melotte~66 looks like a typical object of the old thin disk population.Comment: 14 pages, 18 eps figure, in press in Astronomy and Astrophysics. Abstract shortened to fit arXiv constraint

Chemical abundance analysis of the old, rich open cluster Trumpler 20

Trumpler 20 is an open cluster located at low Galactic longitude, just beyond the great Carina spiral arm, and whose metallicity and fundamental parameters were very poorly known until now. As it is most likely a rare example of an old, rich open cluster -- possibly a twin of NGC 7789 -- it is useful to characterize it. To this end, we determine here the abundance of several elements and their ratios in a sample of stars in the clump of Trumpler 20. The primary goal is to measure Trumpler 20 metallicity, so far very poorly constrained, and revise the cluster's fundamental parameters. We present high-resolution spectroscopy of eight clump stars. Based on their radial velocities, we identify six bona fide cluster members, and for five of them (the sixth being a fast rotator) we perform a detailed abundance analysis. We find that Trumpler 20 is slightly more metal-rich than the Sun, having [Fe/H]=+0.09$\pm$0.10. The abundance ratios of alpha-elements are generally solar. In line with recent studies of clusters as old as Trumpler 20, Ba is overabundant compared to the Sun. Our analysis of the iron-peak elements (Cr and Ni) does not reveal anything anomalous. Based on these results, we re-estimate the cluster age to be 1.5$^{+0.2}_{-0.1}$ Gyr. Its distance to the Galactic centre turns out to be 7.3 kpc. With this distance and metallicity, Trumpler 20 fits fairly well in the metallicity gradient for the galactic inner disc. With this new study, the characterization of Trumpler~20 is now on much more solid ground. Further studies should focus on the estimate of the binary fraction and on its main sequence membership.Comment: 13 pages, 6 eps figures, in press in Astronomy and Astrophysic

Semi-analytical static analysis of nonlocal strain gradient laminated composite nanoplates in hygrothermal environment

AbstractIn this work, the bending behavior of nanoplates subjected to both sinusoidal and uniform loads in hygrothermal environment is investigated. The present plate theory is based on the classical laminated thin plate theory with strain gradient effect to take into account the nonlocality present in the nanostructures. The equilibrium equations have been carried out by using the principle of virtual works and a system of partial differential equations of the sixth order has been carried out, in contrast to the classical thin plate theory system of the fourth order. The solution has been obtained using a trigonometric expansion (e.g., Navier method) which is applicable to simply supported boundary conditions and limited lamination schemes. The solution is exact for sinusoidal loads; nevertheless, convergence has to be proved for other load types such as the uniform one. Both the effect of the hygrothermal loads and lamination schemes (cross-ply and angle-ply nanoplates) on the bending behavior of thin nanoplates are studied. Results are reported in dimensionless form and validity of the present methodology has been proven, when possible, by comparing the results to the ones from the literature (available only for cross-ply laminates). Novel applications are shown both for cross- and angle-ply laminated which can be considered for further developments in the same topic

Male camel behavior and breeding management strategies: how to handle a camel bull during the breeding season?

The present article reviews male camel behavior and bre eding management strategies, providing an insight into the handling procedures and the most relevant welfare issues on these topics. Furthermore, it suggests some procedures for rearing, handling and collecting semen from camel bulls, based on results that have been achieved in the last twenty years and, recently, literature published with the aim of optimizing dromedary camel breeding. Camels are seasonal breeders and their breeding season (BS) is confined to the coolest winter months of the year; during the BS, also called "rutting period" or "rut", males exhibit morphological, behavioral and endocrinological peculiarities. Short breeding season, low libido and high aggressiveness are still some of the major cause of economic loss, poor reproductive perfor mance and injuries, for camel breeding and industry. The application of ethology to approach, to train and to study camel bulls may be useful in the future to improve camel welfare and productive performances. Strong knowledge of animal learning and correct management procedure could be useful for camel technicians, owners, breeders, but also for veterinarians and others scientists

Olive mill wastewater anaerobically digested : phenolic compounds with antiradical activity

The recovery of phenolic compounds, present in the olive fruits and its by-products, has been intensively studied by the antioxidant properties. Olive mill wastewater (OMW) is a phenolic-rich industrial effluent that can be advantageously valorized by the anaerobic digestion to the methane and agricultural fertilizer productions. The objective of this work was to evaluate the antiradical activity of OMW after anaerobic digestion in order to maximize the valorization of this type of effluents. The digested flow was obtained from an anaerobic hybrid reactor treating OMW at different organic loading rates (OLR), from 3.3 to 7.1 kg COD m3 d-1. OLR rise was applied by increasing progressively the OMW volume fraction from 8 % to 83 % in the feed mixture. The input and output streams, obtained at different OMW volume fractions, were characterized in terms of antiradical activity and phenolic compounds identification and quantification. Despite of the fraction decrease on total phenolic compounds provided by OMW anaerobic digestion, the antiradical activity is still significantly high (EC50 = 3.24) in the digested effluent. Oleuropein was the main phenolic compound present in the substrate before and after anaerobic digestion (about 15 % of the initial value). Others phenolic compounds present are: gallic acid, hydroxytyrosol, tyrosol, and quercetin. These data confirmed that, after the OMW anaerobic treatment to produce biomethane, the remaining flow yet contain useful compounds with antiradical activity

Terrestrial Laser Scanner techniques in the assessment of tsunami impact on the Maddalena peninsula (south-eastern Sicily, Italy)

The coastline of the Maddalena peninsula (south-eastern Sicily, Italy) is characterised by the occurrence of a boulder field associated to an extended soil stripping area and by a gravel/sandy berm. The accumulation of the boulders has been mostly correlated to the impact of the December 28, 1908 tsunami wave. The use of Terrestrial Laser Scanner survey techniques, associated to Differential Global Position System determinations, permits to obtain new data for the assessment of tsunami impact on this coastal area. The computing of the surveyed data using the most recent equations is a useful tool in order to estimate the theoretic inundation limit and to reconstruct its variability in function of the boulders size and of the coastal topography. Moreover, the entire new data set allows to confirm that the hypothesis of the tsunami impact is the most reasonable to explain the occurrence of boulders weighing up to 50 tons on the Maddalena peninsula

IP3 Receptors, Mitochondria, and Ca2+ Signaling: Implications for Aging

The tight interplay between endoplasmic-reticulum-(ER-) and mitochondria-mediated Ca2+ signaling is a key determinant of cellular health and cellular fate through the control of apoptosis and autophagy. Proteins that prevent or promote apoptosis and autophagy can affect intracellular Ca2+ dynamics and homeostasis through binding and modulation of the intracellular Ca2+-release and Ca2+-uptake mechanisms. During aging, oxidative stress becomes an additional factor that affects ER and mitochondrial function and thus their role in Ca2+ signaling. Importantly, mitochondrial dysfunction and sustained mitochondrial damage are likely to underlie part of the aging process. In this paper, we will discuss the different mechanisms that control intracellular Ca2+ signaling with respect to apoptosis and autophagy and review how these processes are affected during aging through accumulation of reactive oxygen species