We study stochastic resonance in an over-damped approximation of the stochastic Duffing oscillator from a random dynamical systems point of view. We analyse this problem in the general framework of random dynamical systems with a nonautonomous forcing. We prove the existence of a unique global attracting random periodic orbit and a stationary periodic measure. We use the stationary periodic measure to define an indicator for the stochastic resonance.

We propose a simple theoretical model for desertification processes based on three actors (soil, seeds, and plants) on a two-dimensional lattice. Each actor is described by a time dependent fermionic operator, and the dynamics is ruled by a self-adjoint Hamilton-like operator. We show that even taking into account only a few parameters, accounting for external actions on the ecosystem or the response to positive feedbacks, the model provides a plausible description of the desertification process, and can be adapted to different ecological landscapes. We first describe the simplified model in one cell. Then, we define the full model on a two-dimensional region, taking into account additional factors such as nonhomogeneities, the competition for resources between plants, and the spread of seeds due to the action of wind or animals. This allows us to explore the effects of positive feedback on slowing down, stopping, or reversing the desertification process.

Regime shifts in ecosystems caused by climatic or anthropogenic factors can happen on a relatively short timescale with relevant economic and social effects, a consideration which motivates the large interest in the literature to this topic. A special case of regime shift is given by desertification transitions in semi-arid ecosystems. One desertification model, recently proposed, seems particularly effective in describing several ecological landscapes, taking into account different ecological mechanisms. This model simulates an ecosystem undergoing a desertification transition in term of a stochastic cellular automaton (SCA) subjected to a damage spreading (DS) transition. On the other hand, it is well known that many DS transitions belong to the directed percolation (DP) universality class under certain rather general conditions. Here we investigate the universality class of the SCA model and we identify the region of parameters space inside which it belongs to the DP class.

The identification of early warning signals for regime shifts in ecosystems is of crucial importance given their impact in terms of economic and social effects. We present here the results of a theoretical study on the desertification transition in semiarid ecosystems under external stress. We performed numerical simulations based on a stochastic cellular automaton model, and we studied the dynamics of the vegetation clusters in terms of percolation theory, assumed as an effective tool for analyzing the geometrical properties of the clusters. Focusing on the role played by the strength of external stresses, measured by the mortality rate m, we followed the progressive degradation of the ecosystem for increasing m, identifying different stages: first, the fragmentation transition occurring at relatively low values of m, then the desertification transition at higher mortality rates, and finally the full desertification transition corresponding to the extinction of the vegetation and the almost complete degradation of the soil, attained at the maximum value of m. For each transition we calculated the spanning probabilities as functions of m and the percolation thresholds according to different spanning criteria. The identification of the different thresholds is proposed as an useful tool for monitoring the increasing degradation of real-world finite-size systems. Moreover, we studied the time fluctuations of the sizes of the biggest clusters of vegetated and nonvegetated cells over the entire range of mortality values. The change of sign in the skewness of the size distributions, occurring at the fragmentation threshold for the biggest vegetation cluster and at the desertification threshold for the nonvegetated cluster, offers new early warning signals for desertification. Other new and robust indicators are given by the maxima of the root-mean-square deviation of the distributions, which are attained respectively inside the fragmentation interval, for the vegetated biggest cluster, and inside the desertification interval, for the nonvegetated cluster.

Il volume raccoglie i saggi di esperte ed eperti di vari settori che discutono, dal punto di vista delle proprie specializzazioni, la questione della scarsa presenza di donne in alcuni campi della ricerca scientifica e tecnologica, e in particolare ai vertici di essa.

Presentazione e discussione di dati e problematiche relative alla sottorappresentazione delle donne nella ricerca scientifica, seguite dalla descrizione e valutazione di alcune azioni svolte in quest'ambito presso l'universita' del Salento nell'ambito del progetto di azioni positive STReGA.

I mutamenti sociali in atto hanno fortemente posto in risalto, negli ultimi anni, le necessità circa un maggiore equilibrio vita-lavoro. L’esigenza in esame, sentita in primo luogo, ovviamente, dai lavoratori, ha progressivamente investito organizzazioni e istituzioni. Il telelavoro ha rappresentato e rappresenta un approccio di soluzione possibile. Il Progetto “Telelab. Laboratorio di telelavoro e conciliazione”, realizzato fra il 2011 e il 2014 presso l’Università del Salento, grazie ad un finanziamento dalla Regione Puglia (nell’ambito dell’Avviso del 2009 sui c.d. Patti sociali di genere) ha avuto per obiettivo, attraverso l’attivazione di un certo numero di postazioni di telelavoro per dipendenti dell’Amministrazione, il favorire le politiche di conciliazione fra aspetti personali e familiari e profili lavorativi dei soggetti coinvolti. Il progetto è stato curato e seguito in ogni sua fase da una “cabina di regia” di professoresse e funzionarie dell’Università di Lecce.

A reasoning strategy is iterative when the initial conclusion suggested by a set of premises is integrated into that set of premises in order to yield additional conclusions. Previous experimental studies on game theory-based strategic games observed difficulty in reasoning iteratively, which has been partly attributed to bounded individual rationality. However, this difficulty has also been attributed to problems in adequately representing the beliefs, actions, and goals of other agents involved in the games. In four experiments, we observed similar difficulties in iterative reasoning in a variety of puzzles and games that did not involve social interactions with other agents, where they can only be caused by individual cognitive boundaries. Our findings are consistent with the hypothesis that an intrinsic difficulty in iterative reasoning originates from a tendency not to revise our initial mental representation of a problem in light of the initial conclusions that it implies.

The identification of early-warning signals of critical transitions represents a crucial issue for semi-arid ecosystems which are strongly exposed to desertification risks. Previous studies in this field suggested that the observation of vegetation patchiness and, in particular, changes in the patch size distributions, could provide early indicators of desertification transitions. Through numerical simulations based on a cellular automaton model, we have investigated the time fluctuation properties of several quantities characterizing the vegetation patterns of semi-arid ecosystems under different conditions. At increasing value of a mortality parameter measuring the strength of external stresses, we have found different and earlier transition indicators, related to the time fluctuations of the biggest cluster size.

Descrizione e analisi di un laboratorio sperimentale di empowerment per ricercatrici in vari ambiti scientifici, svoltosi presso l'universita' del Salento nell'ambito del progetto di azioni positive STReGA (http://strega.unisalento.it)