Linear-Quadratic NN-person and Mean-Field Games with Ergodic Cost

We consider stochastic differential games with $N$ players, linear-Gaussian dynamics in arbitrary state-space dimension, and long-time-average cost with quadratic running cost. Admissible controls are feedbacks for which the system is ergodic. We first study the existence of affine Nash equilibria by means of an associated system of $N$ Hamilton-Jacobi-Bellman and $N$ Kolmogorov-Fokker-Planck partial differential equations. We give necessary and sufficient conditions for the existence and uniqueness of quadratic-Gaussian solutions in terms of the solvability of suitable algebraic Riccati and Sylvester equations. Under a symmetry condition on the running costs and for nearly identical players we study the large population limit, $N$ tending to infinity, and find a unique quadratic-Gaussian solution of the pair of Mean Field Game HJB-KFP equations. Examples of explicit solutions are given, in particular for consensus problems.Comment: 31 page

Sviluppo e sperimentazione di un elettrolita polimerico a membrana per PEMFCs (Polymer Electrolyte Membrane Fuel Cells)

Il presente lavoro si propone di realizzare un prototipo di membrana polimerica a conducibilità protonica con: 1)caratteristiche di trasporto (anche selettivo) adeguate alla tecnologia delle celle a combustibile; 2)conducibilità ionica simile o superiore a quella del Nafion®; 3)costi contenuti; Sono state impiegate le seguenti metodologie: a)metodi di preparazione di membrane per “evaporation-casting”; b)determinazione di conducibilità mediante spettroscopia ad impedenza elettrochimica; c)sperimentazione diretta in cella a combustibile; d)determinazione di permeabilità; e)analisi morfologica al S.E.M

temporal variation in genetic diversity and population structure of burlina cattle breed

We analysed the temporal variation of inbreeding, genetic variability and population structure in the Burlina (BUR) cattle breed. A total of 279 individuals were chosen for the analysis representing a period of 19 years (1991-2010) and analysed using 24 microsatellite markers. A total of 235 alleles were detected in the population with a mean of 9.79±3.91 alleles per locus. In the 19-year period, a stable pattern in the mean number of alleles was found. The mean observed heterozygosity was 0.63 and it was slightly lower than the expected in all birth year groups. Neither an increase nor a decrease in heterozygosity and inbreeding estimates were detected over the years, with the exception of the FIS index which was close to zero in two birth year groups: 2001-2002 and 2006. Absence of bottleneck events was proved and structure analysis revealed an increase in breed complexity over the years and a clear differentiation with the Italian Holstein Friesian cattle breed. Molecular markers were successfully applied in the monitoring of the genetic variability of BUR thus enabling the planning and the application of strategies for the in situ conservation of genetic resources and the improving of breed identity

Dynamic facilitation picture of a higher-order glass singularity

We show that facilitated spin mixtures with a tunable facilitation reproduce, on a Bethe lattice, the simplest higher-order singularity scenario predicted by the mode-coupling theory (MCT) of liquid-glass transition. Depending on the facilitation strength, they yield either a hybrid glass transition or a continuous one, with no underlying thermodynamic singularity. Similar results are obtained for facilitated spin models on a diluted Bethe lattice. The mechanism of dynamical arrest in these systems can be interpreted in terms of bootstrap and standard percolation and corresponds to a crossover from a compact to a fractal structure of the incipient spanning cluster of frozen spins. Theoretical and numerical simulation results are fully consistent with MCT predictions.Comment: 4 pages, 3 figures; minor change

The stock exchange of influencers: a financial approach for studying fanbase variation trends

In many online social networks (OSNs), a limited portion of profiles emerges and reaches a large base of followers, i.e., the so-called social influencers. One of their main goals is to increase their fanbase to increase their visibility, engaging users through their content. In this work, we propose a novel parallel between the ecosystem of OSNs and the stock exchange market. Followers act as private investors, and they follow influencers, i.e., buy stocks, based on their individual preferences and on the information they gather through external sources. In this preliminary study, we show how the approaches proposed in the context of the stock exchange market can be successfully applied to social networks. Our case study focuses on 60 Italian Instagram influencers and shows how their followers short-term trends obtained through Bollinger bands become close to those found in external sources, Google Trends in our case, similarly to phenomena already observed in the financial market. Besides providing a strong correlation between these different trends, our results pose the basis for studying social networks with a new lens, linking them with a different domain

Field trip to the Ischia resurgent caldera, a journey across an active volcano in the Gulf of Naples

Ischia is one of the most impressive examples of post-caldera resurgence in the world, with its almost 1,000 m of uplift in less than 30 ka. This three-days field trip will lead the participants through the geological and volcanological history of the island, illustrating the volcanic and related hazardous phenomena threatening about 50,000 inhabitants. Effusive and explosive eruptions, catastrophic earthquakes and huge debris-avalanches struck the island that, since Neolithic times, experienced a complex history of alternating human colonization and natural disasters. The field trip consists of three routes: 1) the circumnavigation of the island, aimed to outline its main volcanological, geomorphological and tectonic features and to observe the oldest volcanic rocks exposed, stimulating discussions about coastal evolution and the relationships between volcanism, volcano-tectonism and slope instability; 2) an onland excursion on peculiar aspects of the products related to Ischia more recent period of volcanic activity; 3) a route focusing on the Mt. Epomeo Green Tuff caldera forming eruptions (55-60 ka), encouraging a discussion on the dynamics of the intracalderic resurgence and the geomorphological evolution of the Mt. Epomeo slopes, with ongoing Mass Rock Creep (MRC) processes culminating in rockavalanche, debris-avalanche and lahar deposits

Fungal environment in different rabbit intensive farms

Many environmental factors (for example, temperature, relative humidity, ventilation, NH3 concentration) can influence the health and welfare of rabbits reared in intensive farms. Among these elements, microorganisms and, in particular, fungi play a pivotal role in the spreading of potential pathogenic and zoonotic diseases. Aim of our work was to evaluate the fungal contamination in two different rabbit rearing (A and B). SAS System® (PBI International, Italy) and opened plates, filled with cultural media for fungal growth (environmental and dermatophytes) have been used. The data collected in both the farms showed that, for environmental fungi, Aspergillus, Alternaria and Penicillium were the most spread. On the contrary, for dermatophytes, there was a difference between farm A and B. In fact, in the first one Microsporum canis (a known zoonotic agent) has been recovered in high concentration, while in the second rearing we have isolated Microsporum gypseum a geophilic fungus with a very low pathogenic potential