Expectations, Animal Spirits, and Evolutionary Dynamics

We consider a (deterministic) evolutionary model where players have dynamic expectations about the strategy distribution. We provide a global analysis of the co-evolution of play and expectations for a generic two{by{two game. Besides the the typical indeterminacy of the evolutionary dynamics, we find some other ones: for any initial strategy configuration the dynamics can converge to any asymptotically stable fixed point, for different initial values of the expectations. Moreover, starting from the same initial pair of strategy configuration and values of expectations, the dynamics may lead to different asymptotically stable fixed points for different parameters of the expectations.evolutionary games, dynamic systems, animal spirits

Global Analysis of an Expectations Augmented Evolutionary Dynamics

We consider a deterministic evolutionary model where players form expectations about future play. Players are not fully rational and have expectations that change over time in response to current payoffs and feedback from the past. We provide a complete characterization of the qualitative dynamics so induced for a two strategies population game,and relate our findings to standard evolutionary dynamics and equilibrium selection when agents have rational forward looking expectationsevolutionary games; dynamic systems; bounded rationality

The Lucca Comics and Games Festival as a platform for transformational cultural tourism: Evidence from the perceptions of residents

There is ample literature on residents' perceptions of the costs and benefits of tourism activities. Much less attention has been provided to residents' perceptions of transformational cultural events redefining local identity and tourism demand. We examine one such case study, the Lucca Comics and Games (LCAG), whose interest also derives from the fact that Lucca is an established Italian heritage city, with relevant attraction capacity for traditional heritage tourism. We have administered a questionnaire to a sample of the local population (411 interviews), with high educational and cultural access levels. We find that LCAG-related tourism is perceived to have differential impact with respect to tourism in general on several dimensions of interest, both in terms of perceived costs and benefits, also as an effect of cognitive biases. Our results provide interesting implications in terms of the role of transformational cultural events such as LCAG in driving change in heritage cities

Silver-containing antimicrobial membrane based on chitosan-TPP hydrogel for the treatment of wounds

Treatment of non-healing wounds represents hitherto a severe dilemma because of their failure to heal caused by repeated tissue insults, bacteria contamination and altered physiological condition. This leads to face huge costs for the healthcare worldwide. To this end, the development of innovative biomaterials capable of preventing bacterial infection, of draining exudates and of favoring wound healing is very challenging. In this study, we exploit a novel technique based on the slow diffusion of tripolyphosphate for the preparation of macroscopic chitosan hydrogels to obtain soft pliable membranes which include antimicrobial silver nanoparticles (AgNPs) stabilized by a lactose-modified chitosan (Chitlac). UV-Vis and TEM analyses demonstrated the time stability and the uniform distribution of AgNPs in the gelling mixture, while swelling studies indicated the hydrophilic behavior of membrane. A thorough investigation on bactericidal properties of the material pointed out the synergistic activity of chitosan and AgNPs to reduce the growth of S. aureus, E. coli, S. epidermidis, P. aeruginosa strains and to break apart mature biofilms. Finally, biocompatibility assays on keratinocytes and fibroblasts did not prove any harmful effects on the viability of cells. This novel technique enables the production of bioactive membranes with great potential for the treatment of non-healing wounds

Topology optimization-guided stiffening of composites realized through Automated Fiber Placement

The paper proposes a mixed strain- and stress-based topology optimization method for designing the ideal geometry of carbon fibers in composite laminates subjected to either applied tractions or prescribed displacements. On the basis of standard micromechanical approaches, analytical elastic solutions for a single cell, assumed to be a Representative Volume Element (RVE), are ad hoc constructed by involving anisotropy induced by fiber orientation and volume fraction, also taking into account inter-laminar stresses and strains. The analytical solutions are then implemented in a Finite Element (FE) custom-made topology optimization-based procedure rewritten to have as output the best curves the reinforcing fibers have to draw in any composite laminate layer to maximize the overall panel stiffness or to minimize the elastic energy. To verify the effectiveness of the proposed strategy, different structures undergoing either in-plane or out-plane boundary conditions have been selected and theoretically investigated, determining the optimal fibers’ maps and showing the related results in comparison to standard sequences of alternate fibers disposition for the same composites. Two optimized panels were at the end actually produced using an innovative Automated Fiber Placement (AFP) machine and consolidating the materials by means of autoclave curing processes, in this way replicating the fiber paths obtained from theoretical outcomes. As a control, two corresponding composite structures were also built without employing the fiber optimization strategy. The panels have been tested in laboratory and the theoretical results have been compared with the experimental findings, showing a very good agreement with our predictions and confirming the capability of the proposed algorithm in suggesting the arrangement of the fibers to obtain enhanced mechanical performances. It is felt that the hybrid analytical-FE topology optimization strategy, in conjunction with the possibilities offered by AFP devices, could pave the way for a new generation of ultra-lightweight composites for aerospace, automotive and many industrial applications

Nucleation, reorganization and disassembly of an active network from lactose-modified chitosan mimicking biological matrices

Developing synthetic materials able to mimic micro- and macrorheological properties of natural networks opens up to novel applications and concepts in materials science. The present contribution describes an active network based on a semi-synthetic polymer, a lactitol-bearing chitosan derivative (Chitlac), and a transient inorganic cross-linker, boric acid. Due to the many and diverse anchoring points for boric acid on the flanking groups of Chitlac, the cross-links constantly break and reform in a highly dynamic fashion. The consequence is a network with unusual non-equilibrium and mechanical properties closely resembling the rheological behavior of natural three-dimensional arrangements and of cytoskeleton. Concepts like network nucleation, reorganization and disassembly are declined in terms of amount of the cross-linker, which acts as a putative motor for remodeling of the network upon application of energy. The out-of-equilibrium and non-linear behavior render the semi-synthetic system of great interest for tissue engineering and for developing in-vitro mimics of natural active matrices

Deferiprone versus Deferoxamine in Sickle Cell Disease: Results from a 5-year long-term Italian multi-center randomized clinical trial.

Blood transfusion and iron chelation currently represent a supportive therapy to manage anemia, vasculopathy and vaso-occlusion crises in Sickle-Cell-Disease. Here we describe the first 5-year long-term randomized clinical trial comparing Deferiprone versus Deferoxamine in patients with Sickle-Cell-Disease. The results of this study show that Deferiprone has the same effectiveness as Deferoxamine in decreasing body iron burden, measured as repeated measurements of serum ferritin concentrations on the same patient over 5-years and analyzed according to the linear mixed-effects model (LMM) (p=0.822). Both chelators are able to decrease, significantly, serum ferritin concentrations, during 5-years, without any effect on safety (p=0.005). Moreover, although the basal serum ferritin levels were higher in transfused compared with non-transfused group (p=0.031), the changes over time in serum ferritin levels were not statistically significantly different between transfused and non-transfused cohort of patients (p=0.389). Kaplan-Meier curve, during 5-years of study, suggests that Deferiprone does not alter survival in comparison with Deferoxamine (p=0.38). In conclusion, long-term iron chelation therapy with Deferiprone was associated with efficacy and safety similar to that of Deferoxamine. Therefore, in patients with Sickle-Cell-Disease, Deferiprone may represent an effective long-term treatment option