SPIDER X - Environmental effects in central and satellite early-type galaxies through the stellar fossil record

A detailed analysis of how environment affects the star formation history of early-type galaxies (ETGs) is undertaken via high signal to noise ratio stacked spectra obtained from a sample of 20,977 ETGs (morphologically selected) from the SDSS-based SPIDER survey. Two major parameters are considered for the study: the central velocity dispersion (sigma), which relates to local drivers of star formation, and the mass of the host halo, which relates to environment-related effects. In addition, we separate the sample between centrals (the most massive galaxy in a halo) and satellites. We derive trends of age, metallicity, and [alpha/Fe] enhancement, with sigma. We confirm that the major driver of stellar population properties in ETGs is velocity dispersion, with a second-order effect associated to the central/satellite nature of the galaxy. No environmental dependence is detected for satellite ETGs, except at low sigma - where satellites in groups or in the outskirts of clusters tend to be younger than those in the central regions of clusters. In contrast, the trends for centrals show a significant dependence on halo mass. Central ETGs in groups (i.e. with a halo mass >10^12.5 M_Sun) have younger ages, lower [alpha/Fe], and higher internal reddening, than "isolated" systems (i.e. centrals residing in low-mass, <10^12.5 M_Sun, halos). Our findings imply that central ETGs in groups formed their stellar component over longer time scales than "isolated" centrals, mainly because of gas-rich interactions with their companion galaxies.Comment: 22 pages, 19 figures, accepted for publication in MNRA

A Comparative Study of Some Markov Random Fields and Different Criteria Optimization in Image Restoration

The present chapter illustrates the use of some recent alternative methods to deal with digital image filtering and restoration. This collection of methods is inspired on the use of Markov Random Fields (MRF), which introduces prior knowledge of information that will allow, more efficiently, modeling the image acquisition process. The methods based on the MRF are analyzed and proposed into a Bayesian framework and their principal objective is to eliminate noise and some effects caused by excessive smoothness on the reconstruction process of images which are rich in contours or edges. In order to preserve object edges into the image, the use of certain convexity criteria into the MRF is proposed obtaining adequate weighting of cost functions in cases where discontinuities are remarked and, even better, for cases where such discontinuities are very smooth

Epidemiology and clinical aspect of mushroom poisonings in South Sardinia: A 10-year retrospective analysis (2011-2021)

Mushroom poisoning is a severe problem of public health, however, information about its epidemiology and management is still limited. This is the first study focused on Sardinia that investigates data about mushroom poisoning describing epidemiology, clinical presentation, seasonality, and the most common involved species. In this retrospective study, we analyzed data recovered from the database of Mycological Inspectorates during a 10-year period (2011-2021). Overall, 164 cases of mushroom poisoning have been identified, with significant peaks in autumn. The highest number of episodes of intoxication were recorded in Cagliari (64), followed by Carbonia (55) and Sanluri (45), although the annual distribution of cases among the provinces varied considerably in the study period. Thanks to the expertise of the Mycological Inspectorate service, the implicated species have been identified in 162 cases (98.78%); 81 cases were caused by toxic species, 60 by edible, and 45 by not edible species. Omphalotus olearius and Agaricus xanthodermus were the most represented toxic species (22% and 18%, respectively); Boletus aereus (18%) was the most frequent edible species, while Boletaceae were the prevalent not edible mushrooms. The data collected in South Sardinia over a period of 10-years demonstrate how a correct and rapid recognition of mushroom poisoning is important to improve the prognosis of patients, however, there are still problems of lack of knowledge, on the part of the population, on the existence of the consultancy services. Because most illnesses from poisonous mushroom ingestion are preventable, increased public awareness about the potential dangers of mushroom poisoning is mandatory

On the Nature of Fossil Galaxy Groups: Are they really fossils ?

We use SDSS-DR4 photometric and spectroscopic data out to redshift z~0.1 combined with ROSAT All Sky Survey X-ray data to produce a sample of twenty-five fossil groups (FGs), defined as bound systems dominated by a single, luminous elliptical galaxy with extended X-ray emission. We examine possible biases introduced by varying the parameters used to define the sample and the main pitfalls are discussed. The spatial density of FGs, estimated via the V/V_ MAX} test, is 2.83 x 10^{-6} h_{75}^3 Mpc^{-3} for L_x > 0.89 x 10^42 h_{75}^-2 erg/s consistent with Vikhlinin et al. (1999), who examined an X-ray overluminous elliptical galaxy sample (OLEG). We compare the general properties of FGs identified here with a sample of bright field ellipticals generated from the same dataset. These two samples show no differences in the distribution of neighboring faint galaxy density excess, distance from the red sequence in the color-magnitude diagram, and structural parameters such as a$_{4}$ and internal color gradients. Furthermore, examination of stellar populations shows that our twenty-five FGs have similar ages, metallicities, and $\alpha$-enhancement as the bright field ellipticals, undermining the idea that these systems represent fossils of a physical mechanism that occurred at high redshift. Our study reveals no difference between FGs and field ellipticals, suggesting that FGs might not be a distinct family of true fossils, but rather the final stage of mass assembly in the Universe.Comment: 18 pages, Accepted to A