High-redshift quasars host galaxies: is there a stellar mass crisis?

We investigate the evolutionary properties of a sample of quasars at 5<z<6.4 using the semi-analytical hierarchical model GAMETE/QSOdust. We find that the observed properties of these quasars are well reproduced by a common formation scenario in which stars form according to a standard IMF, via quiescent star formation and efficient merger-driven bursts, while the central BH grows via gas accretion and BH-BH mergers. Eventually, a strong AGN driven wind starts to clear up the ISM of dust and gas, damping the star formation and un-obscuring the line of sight toward the QSO. In this scenario, all the QSOs hosts have final stellar masses in the range $(4-6)\times 10^{11} M_{sun}$, a factor 3-30 larger than the upper limits allowed by the observations. We discuss alternative scenarios to alleviate this apparent tension: the most likely explanation resides in the large uncertainties that still affect dynamical mass measurements in these high-z galaxies. In addition, during the transition between the starburst-dominated and the active QSO phase, we predict that about 40% of the progenitor galaxies can be classified as Sub Millimeter Galaxies, although their number rapidly decreases with redshift.Comment: 14 pages, 9 figures, accepted for publication in MNRA

Talenti locali, pubblico nazionale, format globale: X Factor Italia tra omologazione e adattamento

I talent show sono forme di intrattenimento televisivo diffuse a partire dagli anni Duemila. Una delle più popolari tipologie di talent show è costituita dai cosiddetti talent show musicali: si tratta di spettacoli costruiti attorno alle performances canore dei concorrenti, il cui scopo è individuare una nuova pop star da lanciare nel mercato discografico. Diversi format (1) di talent show musicali sono stati ideati in diversi paesi negli ultimi quindici anni, e successivamente si sono diffusi in tutto il mondo. L’origine di questo tipo di prodotti è da ricercarsi in Gran Bretagna, dove nel 2001 è stato ideato il primo talent show musicale (Pop Idol) seguito nel 2004 dal format X Factor. Entrambi sono format di grande successo e diffusione, tuttora prodotti in diverse edizioni. L’obiettivo di questo articolo è porre l’accento sulla rilevanza dei talent show nel quadro di una riflessione in chiave geografica e territoriale sulla musica, attraverso un focus sulla circolazione dei format e sulle loro mutazioni e adattamenti

Faint progenitors of luminous z ∼ 6 quasars: Why do not we see them?

Observational searches for faint active nuclei at z > 6 have been extremely elusive, with a few candidates whose high-z nature is still to be confirmed. Interpreting this lack of detections is crucial to improve our understanding of high-z supermassive black holes (SMBHs) formation and growth. In this work, we present a model for the emission of accreting black holes (BHs) in the X-ray band, taking into account super-Eddington accretion, which can be very common in gas-rich systems at high-z. We compute the spectral energy distribution for a sample of active galaxies simulated in a cosmological context, which represent the progenitors of a z ˜ 6 SMBH with MBH ˜ 109 M⊙. We find an average Compton-thick fraction of ˜45 per cent and large typical column densities (NH ≳ 1023 cm2). However, faint progenitors are still luminous enough to be detected in the X-ray band of current surveys. Even accounting for a maximum obscuration effect, the number of detectable BHs is reduced at most by a factor of 2. In our simulated sample, observations of faint quasars are mainly limited by their very low active fraction (fact ˜ 1 per cent), which is the result of short, supercritical growth episodes. We suggest that to detect high-z SMBHs progenitors, large area surveys with shallower sensitivities, such as COSMOS Legacy and XMM-LSS+XXL, are to be preferred with respect to deep surveys probing smaller fields, such as Chandra Deep Field South

Investigating the Integration of Cultural Heritage Disaster Risk Management into Urban Planning Tools. The Ravenna Case Study

As increasingly recognized by scholars, climate change is posing new challenges in the field of disaster risk management and urban planning. Even though cultural heritage has passed through decades and centuries, it has never experienced such unexpected and variable events as those forecasted by climate change for the foreseeable future, making it a sensitive element of the living environment. By selecting the city of Ravenna and the cultural heritage site of the Santa Croce Church and archaeological area as a case study, the paper aims at providing an insight into the role that urban planning tools have when it comes to improving the resilience of historical areas, coping with climate change through improvements to the disaster risk management of cultural heritage. Starting from a deep analysis of the existing spatial and urban planning tools that operate at different scales on the Ravenna territory, the adaptive capacity of the historical area toward the identified risks was assessed. The results may lead, on the one hand, to improving the integration of cultural heritage risk management into urban planning tools; on the other hand, they contribute to improving the scope and the governance of the heritage management plans in order to cope with climate change risks and their effects

Dexamethasone in glioblastoma multiforme therapy : mechanisms and controversies

Glioblastoma multiforme (GBM) is the most common and malignant of the glial tumors. The world-wide estimates of new cases and deaths annually are remarkable, making GBM a crucial public health issue. Despite the combination of radical surgery, radio and chemotherapy prognosis is extremely poor (median survival is approximately 1 year). Thus, current therapeutic interventions are highly unsatisfactory. For many years, GBM-induced brain oedema and inflammation have been widely treated with dexamethasone (DEX), a synthetic glucocorticoid (GC). A number of studies have reported that DEX also inhibits GBM cell proliferation and migration. Nevertheless, recent controversial results provided by different laboratories have challenged the widely accepted dogma concerning DEX therapy for GBM. Here, we have reviewed the main clinical features and genetic and epigenetic abnormalities underlying GBM. Finally, we analyzed current notions and concerns related to DEX effects on cerebral oedema, cancer cell proliferation and migration and clinical outcome.peer-reviewe

Dust formation in the winds of AGBs: the contribution at low metallicities

We present new models for the evolution of stars with mass in the range 1Msun < M < 7.5Msun, followed from the pre-main-sequence through the asymptotic giant branch phase. The metallicity adopted is $Z=3*10^{-4} (which, with an alpha-enhancement of +0.4, corresponds to [Fe/H]=-2). Dust formation is described by following the growth of dust grains of various types as the wind expands from the stellar surface. Models with mass M>3Msun experience Hot Bottom Burning, thus maintaining the surface C/O below unity. Unlike higher Z models, the scarcity of silicon available in the envelope prevents the formation of silicates in meaningful quantities, sufficient to trigger the acceleration of the wind via radiation pressure on the dust grains formed. No silicate formation occurs below a threshold metallicity of Z=10^{-3}. Low--mass stars, with M< 2.5Msun become carbon stars, forming solid carbon dust in their surroundings. The total dust mass formed depends on the uncertain extent of the inwards penetration of the convective envelope during the Third Dredge--Up episodes following the Thermal Pulses. Carbon grains have sizes 0.08 micron < a_C < 0.12 micron and the total amount of dust formed (increasing with the mass of the star) is M_C=(2-6)*10^{-4}Msun. Our results imply that AGB stars with Z=3*10^{-4} can only contribute to carbon dust enrichment of the interstellar medium on relatively long timescales, > 300 Myr, comparable to the evolutionary time of a 3Msun star. At lower metallicities the scarcity of silicon available and the presence of Hot Bottom Burning even in M< 2Msun, prevents the formation of silicate and carbon grains. We extrapolate our conclusion to more metal--poor environments, and deduce that at Z < 10^{-4} dust enrichment is mostly due to metal condensation in supernova ejecta.Comment: 13 pages, 8 figures, accepted for publication on MNRA

Investigation of the synergistic effect of hydrogen peroxide and ultrasound on the photocatalytic treatment under visible light of dyes wastewater

A photocatalytic process under visible light irradiation (LED lamp 13 W) assisted by ultrasound and hydrogen peroxide was investigated, aiming at enhancing the hydroxyl radical production compared to simple photocatalysis. Several parameters, including ultrasound power and H2O2 concentration, were investigated in the degradation of Rhodamine B. Fe doped TiO2 synthesized by the solid-state method was used as the photocatalyst. The synergistic effects between photocatalysis, ultrasound, and H2O2 were studied, and the absence of synergy between photocatalysis and ultrasound was demonstrated. Instead, a synergistic effect was observed between photocatalysis and hydrogen peroxide addition, in fact, the combination of photocatalysis with H2O2 was demonstrated to totally remove the Rhodamine B (5 ppm) in 2 h, as contaminant removal was greater (by 50 %) when the two treatments were used simultaneously than the removal observed in the individual treatments, attributable to the Fenton reaction that promoted the hydroxyl radicals production

Wine Intake in the Framework of a Mediterranean Diet and Chronic Non-Communicable Diseases: A Short Literature Review of the Last 5 Years

Dietary habits are a determining factor of the higher incidence and prevalence of chronic non-communicable diseases (NCDs). In the aim to find a possible preventive and intervention strategy, the Mediterranean diet (MedDiet) has been proposed as an effective approach. Within the MedDiet, moderate wine consumption with meals is a positive item in the MedDiet score; however, recent studies have reported a dose-response association between alcohol consumption and higher risk of a large number of NCDs. This review aimed to evaluate the association between NCDs and wine consumption in the framework of the MedDiet, with a simple review of 22 studies of the highest-level literature published over the last five years. We found that the information regarding the effects of wine in different health outcomes has not varied widely over the past five years, finding inconclusive results among the studies evaluated. Most of the literature agrees that light to moderate wine intake seems to have beneficial effects to some extent in NCDs, such as hypertension, cancer, dyslipidemia and dementia, but no definitive recommendations can be made on a specific dose intake that can benefit most diseases

Artificial Neural Networks for Predicting the Water Retention Curve of Sicilian Agricultural Soils

Modeling soil-water regime and solute transport in the vadose zone is strategic for estimating agricultural productivity and optimizing irrigation water management. Direct measurements of soil hydraulic properties, i.e., the water retention curve and the hydraulic conductivity function, are often expensive and time-consuming, and represent a major obstacle to the application of simulation models. As a result, there is a great interest in developing pedotransfer functions (PTFs) that predict the soil hydraulic properties from more easily measured and/or routinely surveyed soil data, such as particle size distribution, bulk density (ρb), and soil organic carbon content (OC). In this study, application of PTFs was carried out for 359 Sicilian soils by implementing five different artificial neural networks (ANNs) to estimate the parameter of the van Genuchten (vG) model for water retention curves. The raw data used to train the ANNs were soil texture, ρb, OC, and porosity. The ANNs were evaluated in their ability to predict both the vG parameters, on the basis of the normalized root-mean-square errors (NRMSE) and normalized mean absolute errors (NMAE), and the water retention data. The Akaike's information criterion (AIC) test was also used to assess the most efficient network. Results confirmed the high predictive performance of ANNs with four input parameters (clay, sand, and silt fractions, and OC) in simulating soil water retention data, with a prediction accuracy characterized by MAE = 0.026 and RMSE = 0.069. The AIC efficiency criterion indicated that the most efficient ANN model was trained with a relatively low number of input nodes