Optimal curing policy for epidemic spreading over a community network with heterogeneous population

The design of an efficient curing policy, able to stem an epidemic process at an affordable cost, has to account for the structure of the population contact network supporting the contagious process. Thus, we tackle the problem of allocating recovery resources among the population, at the lowest cost possible to prevent the epidemic from persisting indefinitely in the network. Specifically, we analyze a susceptible-infected-susceptible epidemic process spreading over a weighted graph, by means of a first-order mean-field approximation. First, we describe the influence of the contact network on the dynamics of the epidemics among a heterogeneous population, that is possibly divided into communities. For the case of a community network, our investigation relies on the graph-theoretical notion of equitable partition; we show that the epidemic threshold, a key measure of the network robustness against epidemic spreading, can be determined using a lower-dimensional dynamical system. Exploiting the computation of the epidemic threshold, we determine a cost-optimal curing policy by solving a convex minimization problem, which possesses a reduced dimension in the case of a community network. Lastly, we consider a two-level optimal curing problem, for which an algorithm is designed with a polynomial time complexity in the network size.Comment: to be published on Journal of Complex Network

Regeneration section of CO2 capture plant by MEA scrubbing with a rate-based model

CO2 capture from exhaust gas of power plants, natural gas and refinery gas can be successfully achieved by chemical absorption with alkanolamines. CO2 capture from exhaust gas is often obtained by absorption with monoethanolamine (MEA) which is the most frequently used solvent for this purpose. Our paper focuses on the regeneration section, where the amine solution is separated from the absorbed CO2 and recirculated to the absorber. Since regeneration is obtained in a stripper or a distillation column, it is the most energy demanding unit of the plant, so a careful modeling is required. Thermodynamics, kinetics and mass transfer influence the chemical absorption process. Acidic gases and amines are weak electrolytes, which partially dissociate in the aqueous phase: the high non-ideality of the liquid phase must be properly taken into account, by employing a γ/φ method. Kinetics and mass transfer can be described using two different approaches: the “equilibrium-based stage efficiency” model or the “rate-based” one. ASPEN Plus® uses the rate-based model, but the prediction of mass transfer coefficients is based on the film theory by Lewis and Whitman, while other theories can more conveniently be used, i.e. the Eddy Diffusivity theory. Since ASPEN Plus® simulator is suitable to be user customized, it has been chosen as framework for the model proposed in this work, that was validated by comparing simulation results with experimental data of a pilot plant for the purification of exhaust gas from power plant

Regeneration Section of CO2 Capture Plant by MEA Scrubbing with a Rate-Based Model

CO2 capture from exhaust gas of power plants, natural gas and refinery gas can be successfully achieved by chemical absorption with alkanolamines. CO2 capture from exhaust gas is often obtained by absorption with monoethanolamine (MEA) which is the most frequently used solvent for this purpose. Thermodynamics, kinetics and mass transfer influence the chemical absorption process. Acidic gases and amines are weak electrolytes, which partially dissociate in the aqueous phase: the high non-ideality of the liquid phase must be properly taken into account, by employing a γ/φ method. Kinetics and mass transfer can be described using two different approaches: the “equilibrium-based stage efficiency” model or the “rate-based” one. ASPEN Plus® uses the rate-based model, but the prediction of mass transfer coefficients is based on the film theory by Lewis and Whitman, while other theories can more conveniently be used, i.e. the Eddy Diffusivity theory. Since ASPEN Plus® simulator is suitable to be user customized, it has been chosen as framework for the model proposed in this work, that was validated by comparing simulation results with experimental data of a pilot plant for the purification of exhaust gas from power plant by means of MEA washing

CFD investigation on the aerodynamic interferences between medium-solidity Darrieus Vertical Axis Wind Turbines

The present study contributes to understand physical mechanisms involved in an achievable power enhancement by setting vertical axis wind turbines in close proximity. The turbines are straight-bladed Darrieus micro-turbines characterized by medium-high solidity and therefore low tip-speed ratio. Preliminary CFD simulations of the isolated turbine explain the reasons why it has a low power output, namely which are laminar flow and laminar separation bubbles on the blades. This fact is expected also considering the low Reynolds number. Subsequently a campaign of CFD simulations has been performed to analyse the aerodynamic interferences in two-rotor configurations. The behaviour of counter-rotating and co-rotating arrangements is analysed at different distances between rotor axes. The simulations show an increasing of power production of about 10% compared to results for the isolated turbine, independently of the sense of rotation. In order to verify wheter vortex shedding suppression might be the cause of the enhanced performance interactions has been simulated between two closely spaced Magnus spinning cylinders with the same tip-speed ratio of the turbines. These last results don’t show reasonable analogies with VAWT wake structures and interactions. Our main conclusion is that accelerated free-stream flow between the turbines is the principle cause of the power extraction enhancement by means of contraction and re-energisation of the turbine wakes. CFD predictions of a four-rotor configuration confirm our hypothesis, nevertheless the wind direction strongly affects the overall efficacy

Il sequestro come vincolo ai patrimoni criminali: dall'indisponibilità temporanea del bene, all'ablazione

Il sequestro di prevenzione come strumento di aggressione ai patrimoni mafiosi è spesso al centro dei dibattiti di politica giudiziaria e di analisi sociologica. Tuttavia, in materia di sequestri l’ordinamento italiano presenta diversi casi di omonimia che molto spesso creano confusione e sulle quali è necessario dissipare dubbi e perplessità. Nel testo in oggetto si propone una breve panoramica dei sequestri previsti dalla codificazione nazionale distinguendone la natura, le finalità e gli effetti. Ci si sofferma con particolare attenzione sulle due tipologie di sequestro che portano alla confisca dei beni della criminalità organizzata e al loro utilizzo a fini sociali. Il primo, il sequestro di prevenzione ex art. 20 c.a. (codice antimafia), appartiene agli strumenti di prevenzione e non ha natura sanzionatoria, il secondo, il sequestro ex art 12 sexies, l. n. 356 del 1992, appartiene agli strumenti di aggressione di natura penalistica e può essere applicato in coesistenza con un procedimento penale.The seizure of prevention as an instrument of aggression to the Mafia assets is often at the center of the debates of judicial policy and sociological analysis. However, in the field of seizures, the Italian legislation presents several cases of homonym that very often create confusion. Cases on which it is necessary to dispel doubts and perplexities. The text in question proposes a brief overview of the seizures envisaged by the national codification, distinguishing its nature, purpose and effects. We dwell with particular attention on the two types of seizure that lead to the confiscation of the assets of organized crime and their use for social purposes. The first, the seizure of prevention ex art. 20 C.A. (anti-mafia code), belongs to the instruments of prevention and has no sanctioning nature, the second, the seizure ex Art 12 sexies, L. No. 356 of 1992, belongs to the instruments of aggression of a penalistic nature and can be applied in coexistence with a Criminal proceedings

I Segretari negli enti locali nel terzo millennio

Questo lavoro cerca di delineare un ritratto della figura del Segretario comunale e provinciale, mettendo in luce un quadro generale delle caratteristiche dell'istituzione ed evidenziandone le varie peculiarità normative all'interno dell'ordinamento che rendono necessarie alcune modifiche nell'ottica del nuovo ordinamento delle autonomie locali

Il lungo passo indietro. Un percorso verso l’affievolimento di uno straordinario strumento di lotta per la criminalità organizzata di stampo mafioso

The scholar of the mafia phenomenon is called with increasing frequency to confront the resilience of the instruments of aggression and prevention that have made it possible to stem the expansion of organized crime. In this contribution, therefore, the special detention regime regulated by Article 41 bis of the Penitentiary Order, with respect to which recent pronouncements by the high courts have fueled a heated political and social debate, is examined.Lo studioso del fenomeno mafioso è chiamato con sempre maggior frequenza a confrontarsi con la tenuta degli strumenti di aggressione e prevenzione che hanno permesso di arginare l’espandersi della criminalità organizzata. In questo contributo, viene dunque preso in esame il regime detentivo speciale regolamentato dall’art. 41 bis dell’ordinamento penitenziario, rispetto al quale le recenti pronunce delle alte corti hanno alimentato un acceso dibattito politico e sociale

Septal Pore Apparatus Ultrastructure in Tremella Foliacea Pers. Ex Fr. and Tremellodon Gelatinosum (Scop.) Pers.

SUMMARYMost Basidiomycetes are characterized by dolipores with parenthesomes that are multiperforate, imperforate or pauciperforate. Electron micrographs of Tremellae, however, show dolipore septa with banded material in the orifices and vesiculate parenthesomes. We have studied the fine structure of Tremella foliacea Pers. ex Fr. and Tremellodon gelatinosum (Scop.) Pers. In these two species we describe several considerable differences which question the phylogeny suggested by some authors, within the Basidiomycetes. Ultrastructural similarities found in the dolipore of Tremella foliacea and in the pore of a few Ascomycetes could suggest that the most primitive dolipore is the Tremella-type

Occupational Therapy in Complex Patients: A Pilot Randomized Controlled Trial

INTRODUCTION: To determine effect size and feasibility of experimental occupational therapy (OT) intervention in addition to standard care in a population of complex patients undergoing rehabilitation in a hospital-home-based setting. METHOD: 40 complex patients admitted to the rehabilitation ward of the Local Health Authority-Research Institute of Reggio Emilia (Italy) were randomized in a parallel-group, open-label controlled trial. Experimental OT targeting occupational needs in the areas of self-care, productivity, and leisure was delivered by occupational therapists. Standard care consisted of task-oriented rehabilitation delivered by a multiprofessional team. RESULTS: The experimental OT intervention was completed by 75% of patients assigned to this group. The average changes in the Canadian Occupational Performance Measure (COPM) performance score significantly and clinically favored experimental OT [-3,06 (-4.50; -1.61); delta > 2 points, resp.]. Similar trends were detected for COPM satisfaction and independence in instrumental activities of daily living (ADL). At follow-up, level of social participation was higher for patients treated with experimental OT (p = 0.043) than for controls. CONCLUSIONS: Experimental OT was feasible in complex patients in a hospital-home-based setting. It ameliorated both patients' performance and satisfaction in carrying out relevant activities and improved independence in instrumental ADL. The trial is registered with ClinicalTrials.gov NCT02677766

Epidemic Outbreaks in Networks with Equitable or Almost-Equitable Partitions

We study the diffusion of epidemics on networks that are partitioned into local communities. The gross structure of hierarchical networks of this kind can be described by a quotient graph. The rationale of this approach is that individuals infect those belonging to the same community with higher probability than individuals in other communities. In community models the nodal infection probability is thus expected to depend mainly on the interaction of a few, large interconnected clusters. In this work, we describe the epidemic process as a continuous-time individual-based susceptible-infected-susceptible (SIS) model using a first-order mean-field approximation. A key feature of our model is that the spectral radius of this smaller quotient graph (which only captures the macroscopic structure of the community network) is all we need to know in order to decide whether the overall healthy-state defines a globally asymptotically stable or an unstable equilibrium. Indeed, the spectral radius is related to the epidemic threshold of the system. Moreover we prove that, above the threshold, another steady-state exists that can be computed using a lower-dimensional dynamical system associated with the evolution of the process on the quotient graph. Our investigations are based on the graph-theoretical notion of equitable partition and of its recent and rather flexible generalization, that of almost equitable partition.Comment: 21 pages, 9 figure