Triggering Active Galactic Nuclei in Hierarchical Galaxy Formation: Disk instability vs. Interactions

Using a semi analytic model for galaxy formation we investigate the effects of Black Hole accretion triggered by disk instabilities (DI) in isolated galaxies on the evolution of AGN. Specifically, we took on, developed and expanded the Hopkins & Quataert (2011) model for the mass inflow following disk perturbations, and compare the corresponding evolution of the AGN population with that arising in a scenario where galaxy interactions trigger AGN (IT mode). We extended and developed the DI model by including different disk surface density profiles, to study the maximal contribution of DI to the evolution of the AGN population. We obtained the following results: i) for luminosities corresponding to $M_{1450}\gtrsim -26$ the DI mode can provide the BH accretion needed to match the observed AGN luminosity functions up to $z \approx 4.5$; in such a luminosity range and redshift, it can compete with the IT scenario as the main driver of cosmological evolution of AGN; ii) The DI scenario cannot provide the observed abundance of high-luminosity QSO with $M_{1450}\lesssim -26$ AGN, as well as the abundance of high-redhshift $z \approx 4.5$ QSOs with $M_{1450}\lesssim -24$, while the IT scenario provides an acceptable match up to $z \approx 6$, as found in our earliest works; iii) The dispersion of the distributions of Eddington ratio for low- and intermediate-luminosity AGN (bolometric $L_{AGN}$ = $10^{43}$ - $10^{45}$ erg/s) is predicted to be much smaller in the DI scenario compared to the IT mode; iv) The above conclusions are robust with respect to the explored variants of the Hopkins & Quataert (2011) model. We discuss the physical origin of our findings, and how it is possible to pin down the dominant fueling mechanism in the low-intermediate luminosity range $M_{1450}\gtrsim -26$ where both the DI and the IT modes are viable candidates as drivers for the AGN evolution.Comment: Accepted for publication in Astronomy & Astrophysics, 24 pages, 8 figures; updated reference

Sense of responsible togetherness, sense of community, and civic engagement behaviours: Disentangling an active and engaged citizenship

Local communities should represent entities where individuals get answers to their affiliation needs and for which they feel responsible, but in modern ones, increasingly complex ways of living together are fostering citizens' civic and social disengagement. The present study addresses the relationships between the cognitive, affective, and behavioural components of an active and engaged citizenship. Five hundred and fifty-five Italian citizens answered an online questionnaire about their Sense of Responsible Togetherness, Sense of Community, and Civic Engagement Behaviours. The results support Sense of Community as a mediator in the relationship between Sense of Responsible Togetherness and civic engagement behaviours, suggesting that the representations about community members being active and responsible, and having opportunities to meet and match, could at the same time strengthen their tie to that community and foster their civic engagement for it. This could set up a cycle of enhancement and empowerment for individuals and communities through increasing the opportunities for local generative interactions and civic engagement

Local community experience as an anchor sustaining reorientation processes during COVID-19 pandemic

In recent months, Italian citizens have alternatively experienced a forced, total or partial, loss of their opportunities to go out and meet their social network or their reduction, according to the restrictions locally needed to contain the spread of the COVID-19 outbreak. The effects of these unprecedented circumstances and restrictions on their local community experience are still to be deepened. Consequently, this study investigated young citizens’ experiences of and attitudes towards their local communities of belonging after ten months of alternatively strict and partially eased restrictions. The World Café methodology was used to favor the exchange of ideas and open new viewpoints among participants. What emerged suggests that the communities of belonging may have worked as anchors to which young citizens clung as an attempt not to be overwhelmed by the disorientation brought about by the loss of their daily life (e.g., routines, life places, face-to-face sociability). On the one hand, this suggests that a renewed focus on local communities and a more involved way of living in them may stem from this tough time. On the other hand, these results point out the need for more meaningful and actively engaged people–community relationships as drivers for recovery processes under emergency circumstances

A robot-based burr measurement system for the automotive industry

Burrs are often difficult to detect and measure because of their intrinsic variability in shape and dimension. No automotive standard had been established about their acceptable dimensions and measurement techniques for sheet steel products. For the automotive industry, even burrs of the size of 100 μm are perceived as damaging because of their dramatic impact upon panel corrosion resistance and assembly performance. It is critical to measure burrs during panel manufacture in order to control the process. The characterization of the typical burr produced has been carried out employing 3D measurements with a surface profilometer and a SEM. This analysis has shown a typical triangular burr shape and some characteristic dimensions. A contact method and two laser-triangulation systems have been developed. The instrument accuracy was analyzed, based upon a full factorial experimentation over a set of typical panels edges

Backscattering Differential Ghost Imaging in Turbid Media

In this Letter we present experimental results concerning the retrieval of images of absorbing objects immersed in turbid media via differential ghost imaging (DGI) in a backscattering configuration. The method has been applied, for the first time to our knowledge, to the imaging of small thin black objects located at different depths inside a turbid solution of polystyrene nanospheres and its performances assessed via comparison with standard imaging techniques. A simple theoretical model capable of describing the basic optics of DGI in turbid media is proposed.Comment: 5 pages, 6 figure

Antimicrobial Dose Reduction in Continuous Renal Replacement Therapy: Myth or Real Need? A Practical Approach for Guiding Dose Optimization of Novel Antibiotics

Acute kidney injury represents a common complication in critically ill patients affected by septic shock and in many cases continuous renal replacement therapy (CRRT) may be required. In this scenario, antimicrobial dose optimization is highly challenging as the extracorporeal circuit may cause several pharmacokinetic alterations, which add up to volume of distribution and clearance variations resulting from sepsis. Variations in CRRT settings (i.e. modality of solute removal, type of filter material, blood flow rate and effluent flow rate), coupled with the presence of residual and/or recovering renal function, may cause dynamic variations in the clearance of hydrophilic antimicrobials. This means that dose reduction may not always be needed. Nowadays, the lack of pharmacokinetic data for novel antimicrobials during CRRT limits evidence-based dose recommendations for critically ill patients in this setting, thus making available evidence hardly applicable in real-world scenarios. This review aims to summarize the major determinants involved in antimicrobial clearance, and the available pharmacokinetic studies performed during CRRT involving novel antibiotics used for the management of multidrug-resistant Gram-positive and Gram-negative infections (namely ceftolozane–tazobactam, ceftazidime–avibactam, cefiderocol, imipenem–relebactam, meropenem–vaborbactam, ceftaroline, ceftobiprole, dalbavancin, and fosfomycin), providing a practical approach in guiding dose optimization in this special population

Sensemaking processes during the first months of COVID-19 pandemic: Using diaries to deepen how Italian youths experienced lockdown measures

The COVID-19 pandemic has brought about disruptive changes in individuals’ lives, breaking the established systems of meaning worldwide. Indeed, in the first months of the pandemic, with individuals being forced to stay at home for a prolonged time to contain the spread of the virus, the need to build new meanings to understand and face this crisis emerged. Building on this, the present study contributes to the understanding of how sensemaking processes were shaped in the face of COVID-19 collective trauma during the very first months of the pandemic. Hence, 36 Italian young adults aged between 21 and 25 submitted daily diary entries for two weeks (T1 was the third week of Italian National lockdown; T2 was the penultimate week before the ease of such stay-at-home orders), resulting in 504 texts. The stimulus was always “Could you describe your daily experience and feelings?”. The Grounded Theory was used. Thus, 15 categories emerged, grouped into three macro-categories. The core category was sensemaking as adaptation. Indeed, the sensemaking process seemed to be a strategy to adapt to the new circumstances related to the lockdown, facing the emotional, cognitive, and activation reactions such conditions by relying on coping strategies and the redefinition of primary as well as broader social relationships

Dark Energy Survey Year 1 results: cross-correlation redshifts – methods and systematics characterization

We use numerical simulations to characterize the performance of a clustering-based method to calibrate photometric redshift biases. In particular, we cross-correlate the weak lensing source galaxies from the Dark Energy Survey Year 1 sample with redMaGiC galaxies (luminous red galaxies with secure photometric redshifts) to estimate the redshift distribution of the former sample. The recovered redshift distributions are used to calibrate the photometric redshift bias of standard photo-z methods applied to the same source galaxy sample. We apply the method to two photo-z codes run in our simulated data: Bayesian Photometric Redshift and Directional Neighbourhood Fitting. We characterize the systematic uncertainties of our calibration procedure, and find that these systematic uncertainties dominate our error budget. The dominant systematics are due to our assumption of unevolving bias and clustering across each redshift bin, and to differences between the shapes of the redshift distributions derived by clustering versus photo-zs. The systematic uncertainty in the mean redshift bias of the source galaxy sample is Δz ≲ 0.02, though the precise value depends on the redshift bin under consideration. We discuss possible ways to mitigate the impact of our dominant systematics in future analyses

Orbital periods of the binary sdB stars PG0940+068 and PG1247+554

We have used the radial velocity variations of two sdB stars previously reported to be binaries to establish their orbital periods. They are PG0940+068, (P=8.33d) and PG1247+554 (P=0.599d). The minimum masses of the unseen companions, assuming a mass of 0.5 solar masses for the sdB stars, are 0.090 +/- 0.003 solar masses for PG1247+554 and 0.63 +/- 0.02 solar masses for PG0940+068. The nature of the companions is not constrained further by our data.Comment: 5 pages, 2 figure