De Giorgi's approach to hyperbolic Cauchy problems: the case of nonhomogeneous equations

In this paper we discuss an extension of some results obtained by E. Serra and P. Tilli, in [Serra&Tilli '12, Serra&Tilli '16], concerning an original conjecture by E. De Giorgi ([De Giorgi '96, De Giorgi '06]) on a purely minimization approach to the Cauchy problem for the defocusing nonlinear wave equation. Precisely, we show how to extend the techniques developed by Serra and Tilli for homogeneous hyperbolic nonlinear PDEs to the nonhomogeneous case, thus proving that the idea of De Giorgi yields in fact an effective approach to investigate general hyperbolic equations.Comment: 24 page

An existence result for dissipative nonhomogeneous hyperbolic equations via a minimization approach

We discuss a purely variational approach to the study of a wide class of second order nonhomogeneous dissipative hyperbolic PDEs. Precisely, we focus on the wave-like equations that present also a nonzero source term and a first-order-in-time linear term. The paper carries on the research program initiated in (Serra&Tilli'12), and developed in (Serra&Tilli'16), (Tentarelli&Tilli '18), on the De Giorgi approach to hyperbolic equations.Comment: 21 pages; keywords: minimization, nonhomogeneous hyperbolic equations, dissipation, De Giorgi conjectur

Analysis, Dimensioning and Robust Control of Shunt Active Filter for Harmonic Currents Compensation in Electrical Mains

In this chapter some results related to Shunt Active Filters (SAFs) and obtained by the authors and some coauthors are reported. SAFs are complex power electronics equipments adopted to compensate for cur-rent harmonic pollution in electric mains, due to nonlinear loads. By using a proper "floating" capacitor as energy reservoir, the SAF purpose is to inject in the line grid currents canceling the polluting har-monics. Control algorithms play a key role for such devices and, in general, in many power electronics applications. Moreover, systems theory is crucial, since it is the mathematical tool that enables a deep understanding of the involved dynamics of such systems, allowing a correct dimensioning, beside an effective control. As a matter of facts, current injection objective can be straightforwardly formulated as an output tracking control problem. In this fashion, the structural and insidious marginally-stable internal/zero dynamics of SAFs can be immediately highlighted and characterized in terms of sizing and control issues. For what concerns the control design strictly, time-scale separation among output and internal dynamics can be effectively exploited to split the control design in different stages that can be later aggregated, by using singular perturbation analysis. In addition, for robust asymptotic output tracking the Internal Model Principle is adopted.Comment: Paper presented at the AUTOMATICA_IT 2011 conference, Pisa, Italy, September 201

Strategies for management of strongyloidiasis in migrants from Sub-Saharan Africa recently arrived in Italy: A cost-effectiveness analysis

Abstract Background The Italian and the European Centre for Disease Control and Prevention guidelines both recommend a systematic serological screening for strongyloidiasis in sub-Saharan migrants (SSA), however, studies on clinical and economic impact of this strategy in the Italian and European settings are lacking. Methods A population of 100,000 migrants from SSA to Italy was considered and a Markov decision tree model was developed to assess the clinical and economic impact of two interventions for strongyloidiasis compared with the current practice (passive diagnosis of symptomatic cases): a) universal serological screening and treatment with ivermectin in case of positive test b) universal presumptive treatment with ivermectin. One and 10-year time horizon in the health-care perspective were considered. Results In the one and 10-year time horizon respectively the costs for passive diagnosis was €1,164,169 and €9,735,908, those for screening option was € 2,856,011 and € 4,959,638 and those for presumptive treatment was €3,538,474 and € 4,883,272. Considering the cost per cured subject in the one-year time horizon, screening appears more favorable (€209.53), than the other two options (€232.55 per presumptive treatment and €10,197.29 per current strategy). Incremental cost-effectiveness ratio (ICERs) of screening strategy and presumptive treatment were respectively 265.27 and 333.19. The sensitivity analysis identified strongyloidiasis' prevalence as the main driver of ICER. Conclusions Compared to the current practice (passive diagnosis) both screening and presumptive treatment strategies are more favorable from a cost-effectiveness point of view, with a slight advantage of the screening strategy in a one-year time horizon

Robust nonlinear control of shunt active filters for harmonic current compensation

An advanced control strategy of Shunt Active Filter (SAF) aiming to compensate for harmonic current in the electric supply grid is proposed. The SAF considered here is suitable for three-phase three-wire current harmonic compensation and is based on AC/DC three-phase boost converter topology. Robust control of the active-reactive current/power delivered by the SAF is designed exploiting the internal model principle. The stabilization of the DC-link voltage dynamics is addressed along with the fulfillment of the harmonics compensation objective. Two-time scale behavior of the SAF is exploited to apply the averaging theory in the control design. Experiments are provided to show the effectiveness of the proposed solution

Neglected tropical diseases in non-endemic countries in the era of COVID-19 pandemic: the great forgotten

No abstract availabl

Presumptive treatment or serological screening for schistosomiasis in migrants from Sub-Saharan Africa could save both lives and money for the Italian National Health System: results of an economic evaluation

Background Schistosomiasis can lead to severe irreversible complications and death if left untreated. Italian and European guidelines recommend serological screening for this infection in migrants from Sub-Saharan Africa (SSA). However, studies on clinical and economic impact of this strategy in the Italian and European settings are lacking. This study aims to compare benefits and costs of different strategies to manage schistosomiasis in migrants from SSA to Italy. Methods A decision tree and a Markov model were developed to assess the health and economic impacts of three interventions: (i) passive diagnosis for symptomatic patients (current practice in Italy); (ii) serological screening of all migrants and treating those found positive and (iii) presumptive treatment for all migrants with praziquantel in a single dose. The time horizon of analysis was one year to determine the exact expenses, and 28 years to consider possible sequelae, in the Italian health-care perspective. Data input was derived from available literature; costs were taken from the price list of Careggi University Hospital, Florence, and from National Hospitals Records. Results Assuming a population of 100 000 migrants with schistosomiasis prevalence of 21 center dot 2%, the presumptive treatment has a greater clinical impact with 86.3% of the affected being cured (75.2% in screening programme and 44.9% in a passive diagnosis strategy). In the first year, the presumptive treatment and the screening strategy compared with passive diagnosis prove cost-effective (299 and 595 cost/QALY, respectively). In the 28-year horizon, the two strategies (screening and presumptive treatment) compared with passive diagnosis become dominant (less expensive with more QALYs) and cost-saving. Conclusion The results of the model suggest that presumptive treatment and screening strategies are more favourable than the current passive diagnosis in the public health management of schistosomiasis in SSA migrants, especially in a longer period analysis