A two-step hybrid approach for modeling the nonlinear dynamic response of piezoelectric energy harvesters

An effective hybrid computational framework is described here in order to assess the nonlinear dynamic response of piezoelectric energy harvesting devices. The proposed strategy basically consists of two steps. First, fully coupled multiphysics finite element (FE) analyses are performed to evaluate the nonlinear static response of the device. An enhanced reduced-order model is then derived, where the global dynamic response is formulated in the state-space using lumped coefficients enriched with the information derived from the FE simulations. The electromechanical response of piezoelectric beams under forced vibrations is studied by means of the proposed approach, which is also validated by comparing numerical predictions with some experimental results. Such numerical and experimental investigations have been carried out with the main aim of studying the influence of material and geometrical parameters on the global nonlinear response. The advantage of the presented approach is that the overall computational and experimental efforts are significantly reduced while preserving a satisfactory accuracy in the assessment of the global behavior

Metastability of Logit Dynamics for Coordination Games

Logit Dynamics [Blume, Games and Economic Behavior, 1993] are randomized best response dynamics for strategic games: at every time step a player is selected uniformly at random and she chooses a new strategy according to a probability distribution biased toward strategies promising higher payoffs. This process defines an ergodic Markov chain, over the set of strategy profiles of the game, whose unique stationary distribution is the long-term equilibrium concept for the game. However, when the mixing time of the chain is large (e.g., exponential in the number of players), the stationary distribution loses its appeal as equilibrium concept, and the transient phase of the Markov chain becomes important. It can happen that the chain is "metastable", i.e., on a time-scale shorter than the mixing time, it stays close to some probability distribution over the state space, while in a time-scale multiple of the mixing time it jumps from one distribution to another. In this paper we give a quantitative definition of "metastable probability distributions" for a Markov chain and we study the metastability of the logit dynamics for some classes of coordination games. We first consider a pure $n$-player coordination game that highlights the distinctive features of our metastability notion based on distributions. Then, we study coordination games on the clique without a risk-dominant strategy (which are equivalent to the well-known Glauber dynamics for the Curie-Weiss model) and coordination games on a ring (both with and without risk-dominant strategy)

Heroin-piracetam mixture: suggested mechanisms of action and risks of misinterpretation for drug users

Piracetam is a positive allosteric modulator of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor that has been frequently used in the treatment of cognitive disorders. Press and internet reports indicate that the use of piracetam, as a heroin adulterant, has spread rapidly in some countries, especially in Asia and Europe. Its use, as adulterant, is believed to produce more profound desirable effects, while decreasing hangover. Recent surveys demonstrated that piracetam protects neurons from heroin-induced apoptosis. The protective role of this adulterating substance may be related to restoration of beta-endorphin levels and to its neuroprotective effects. The aim of this paper is to review the relevant literature and suggest the main hypothetical mechanisms that justify its use as a heroin adulterant, try to understand if its use could help people who want to come off heroin by reducing withdrawal symptoms and, finally, give useful information that permit us to understand why drug trafficking organisations started to use piracetam as heroin adulterant

Convergence to Equilibrium of Logit Dynamics for Strategic Games

We present the first general bounds on the mixing time of the Markov chain associated to the logit dynamics for wide classes of strategic games. The logit dynamics with inverse noise beta describes the behavior of a complex system whose individual components act selfishly and keep responding according to some partial ("noisy") knowledge of the system, where the capacity of the agent to know the system and compute her best move is measured by the inverse of the parameter beta. In particular, we prove nearly tight bounds for potential games and games with dominant strategies. Our results show that, for potential games, the mixing time is upper and lower bounded by an exponential in the inverse of the noise and in the maximum potential difference. Instead, for games with dominant strategies, the mixing time cannot grow arbitrarily with the inverse of the noise. Finally, we refine our analysis for a subclass of potential games called graphical coordination games, a class of games that have been previously studied in Physics and, more recently, in Computer Science in the context of diffusion of new technologies. We give evidence that the mixing time of the logit dynamics for these games strongly depends on the structure of the underlying graph. We prove that the mixing time of the logit dynamics for these games can be upper bounded by a function that is exponential in the cutwidth of the underlying graph and in the inverse of noise. Moreover, we consider two specific and popular network topologies, the clique and the ring. For games played on a clique we prove an almost matching lower bound on the mixing time of the logit dynamics that is exponential in the inverse of the noise and in the maximum potential difference, while for games played on a ring we prove that the time of convergence of the logit dynamics to its stationary distribution is significantly shorter

Archaeobotanical analysis from the long-term rural settlement of Contrada Castro (Corleone, Palermo): preliminary data

The project ¿Harvesting Memories: Ecology and Archaeology of Monti Sicani landscapes¿ aims to analyse the long-term relationship of landscape dynamics and settlement patterns in a Mediterranean inland of Central-Western Sicily. The project combined different interdisciplinary approaches of vegetation science, landscape ecology, history and archaeology in order to diachronically understand and reconstruct the human- society-environment interactions. From 2017 to 2019 a new rural settlement has been investigated in Contrada Castro (Corleone, Palermo). The excavation in Contrada Castro showed a clear case of long-term occupation of an hill-top site during Late Archaic/Classical age (6 th -5 th c. BC) and the Byzantine and Islamic period (7 th -11 th c. AD). Soils from the archaeological excavation were sampled to obtain evidences about paleo-vegetation and vegetal paleo-diet. Archaeobotanical data (seeds and charcoal remains) represent an informative source in human-environmental dynamics to collect specific data on a small scale in terms of chronology and topography (Hastorf, Popper 1988; Pearsall 2009). Furthermore, presence of edible plants as cereals, pulses and fruit characterize their use as economical resources. Unfortunately, archaeobotanical analyses from archaeological sites in Sicily are still not very common (see http://brainplants.successoterra.net/sites.html). For the reconstruction of the paleo-environment and the use of arboreal resources from the three chronological phases of the site, a total of 239 liters of soils were analysed. Taxonomical identification was made by optical microscopy through the comparison with the reference collection and specific atlases (fig.). More than 400 wood charcoals were observed, about 80% of them was identified. Thanks to comparisons with the current vegetation, so far 8 species have been identified - Quercus cfr. ilex (fig.), Pistacia cfr. terebinthus, Rhamnus alathernus, Fraxinus ornus, Ulmus canescens, Acer cfr. campestris, Ostrya carpinifolia, Populus cf. nigra; identification reached the detail of genus or subfamily in 6 cases - Quercus cf. robur / pubescens, Phillyrea sp., Sorbus sp., Rosacea cfr. Pirus sp. and maybe Moracea. The arboreal vegetation is therefore represented by evergreen oaks, semi- and deciduous oaks, maples, ash trees, associated with riparian species such as elm, poplar and hornbeam, and shrub species such as backthorn, terebinth, sorb, plum. Cultivated species are mostly not represented. Despite the widespread presence of the evergreen oaks in the whole record, differences between the three chronological phases were identified, highlighting a selective use of the wild species present in the area and a specific collection of wood for the hearths. 1) Hastorf C.A., Popper V.F.1988, Current Paleoethnobotany. Analytical Methods and Cultural Interpretations of Archaeological Plant Remains, Chicago. ISBN: 978022631893 2) Pearsall D. M. 2009, Paleoethnobotany: A Handbook of Procedures, Second Edition, Walnut Creek. ISBN-10: 1598744720 3) BRAIN Network, http://brainplants.successoterra.net/sites.htmlFinanciación: beca "Juan de la Cierva-incorporación, IJCI-2017-31494, MINECO), IJCI-2017-31494" y proyecto "Harvesting Memories" de la Universidad de Palermo (financiado por Bona Furtuna LLC)

Full phase diagram of active Brownian disks: from melting to motility-induced phase separation

We establish the complete phase diagram of self-propelled hard disks in two spatial dimensions from the analysis of the equation of state and the statistics of local order parameters. The equilibrium melting scenario is maintained at small activities, with coexistence between active liquid and hexatic order, followed by a proper hexatic phase and a further transition to an active solid. As activity increases, the emergence of hexatic and solid order is shifted towards higher densities. Above a critical activity and for a certain range of packing fractions, the system undergoes MIPS and demixes into low and high density phases; the latter can be either disordered (liquid) or ordered (hexatic or solid) depending on activity

Hypopigmented macules of the limbs in two sisters: Report on familial bier spots

Bier spots are asymptomatic, small, irregular, hypopigmented macules characterized by a normal histological appearance, which are usually found on the arms and legs of young adults. We describe the simultaneous presence of Bier spots in two siblings. This finding is unusual since, to the best of our knowledge, concurrent familial cases have never been reported in the literature

Effects of additives and ingredient sizing on the shelf-life of "Amaretti" cookies

Cookies are characterised by moisture and water activity (aw) higher than 7% and 0.5, respectively. Cookies have the capacity of bending after baking, when they are fresh, unlike biscuits that break when bent. Hardening is the main cause of quality deterioration of cookies, which change from soft and pliable to firm and crumbly within a few days or even hours after baking. Little research has been done on cookies. "Amaretti" are typical Italian cookies, found in several regions of Italy. Freshly baked "Amaretti" are soft and delicious but undergo severe hardening after seven to ten days, thus limiting the shelf-life, so Amaretti can be marketed only locally. In the present work several attempts have been made in order to extend the shelf-life of Sardinian "Amaretti". In particular, changes to the formulation and to the almond particle size were made. The traditional formulation was, in fact, modified by adding rice starch (thickening agent) or mono-diglyceride of fatty acids (emulsifier). Almonds were grinded to a particle size lower or higher than 1 mm. Amaretti baked with the traditional recipe were used as control. After baking and cooling cookies were wrapped with an aluminium foil and stored at controlled temperature and humidity. Evolution of texture (as hardness) and aw during storage were followed instrumentally by a texture analyser and a hygrometer, respectively

Satellite SAR Interferometry for Earth’s Crust Deformation Monitoring and Geological Phenomena Analysis

Synthetic aperture radar interferometry (InSAR) and the related processing techniques provide a unique tool for the quantitative measurement of the Earth’s surface deformation associated with certain geophysical processes (such as volcanic eruptions, landslides and earthquakes), thus making possible long-term monitoring of surface deformation and analysis of relevant geodynamic phenomena. This chapter provides an application-oriented perspective on the spaceborne InSAR technology with emphasis on subsequent geophysical investigations. First, the fundamentals of radar interferometry and differential interferometry, as well as error sources, are briefly introduced. Emphasis is then placed on the realistic simulation of the underlying geophysics processes, thus offering an unfolded perspective on both analytical and numerical approaches for modeling deformation sources. Finally, various experimental investigations conducted by acquiring SAR multitemporal observations on areas subject to deformation processes of particular geological interest are presented and discussed