Size, trend, and policy implications of the underground economy

We study the underground economy within a dynamic and stochastic general equilibrium framework. Our model combines limited tax enforcement with an otherwise standard two-sector neoclassical stochastic growth model. The Bayesian estimation of the model based on Italian data provides evidence in favor of an important underground sector in Italy, with a size that has increased steadily over the whole sample period. We show that this pattern is due to a steady increase in taxation. Fiscal policy experiments suggest that a moderate tax cut, along with a stronger effort in the monitoring process, causes a sizeable reduction in the size of the underground economy and provides a positive stimulus for the regular economy. Both of these effects jointly increase total fiscal revenues.Francesco Turino is grateful for the financial support provided by the Spanish Ministerio de Educación y Ciencia and FEDER funds (project SEJ-2007-62656/ECON)

Size, Trend, and Policy Implications of the Underground Economy

We study the underground economy in a dynamic and stochastic general equilibrium framework. Our model combines limited tax enforcement with an otherwise standard two-sector neoclassical stochastic growth model. The Bayesian estimation of the model based on Italian data provides evidence in favor of an important underground sector in Italy, with a size that has steadily increased over the whole sample period. We show that this pattern is due to a persistent increase in taxation. Fiscal policy experiments suggest that a moderate tax cut, along with a stronger effort in the monitoring process, causes a sensitive reduction in the size of the underground economy and positive stimulus to the regular sector that jointly increase the total fiscal revenues

Caratterizzazione dinamica e reologica di architetture 2D all'interfaccia aria/acqua

This Thesis reports the characterization of the mechanical response and of the internal microscopic dynamics of 2D Langmuir films, performed and interpreted within the theoretical framework provided by fluctuation-response function theorems. The mechanical shear modulus of Langmuir films has been measured by means of the Interfacial Shear Rheology technique (ISR). X-ray photon correlation spectroscopy (XPCS) experiments were performed to characterize the slow microscopic dynamics of samples either at the air/water interface or transferred on solid substrate. Two kind of systems have been investigated: polymeric films made of a photosensitive azobenzene-polyacrylate (PA4), and films of gold nanoparticles (GNPs) forming a 2D gel. Langmuir films of PA4 present an elastic shear response, which can be controlled at will by suitable illumination, induceing photoisomerisation of the azobenzene and therefore a transformation from an elastic to a viscous film. This process is accompanied by an acceleration, of more than one order of magnitude, of the internal dynamics, without a change in any thermodynamic parameter (temperature or surface pressure). Also, back isomerization with blue light acts on the system as an “optical quench”. All this allows the polymer to be brought out of equilibrium- and its dynamics being studied- in a novel and unconventional way. GNPs films are characterized by an heterogeneous morphology, with a foam-like structure at low concentration, and a Levy-distribution of sizes, which is deemed to be at the origin of the elastic, gel-like mechanical response observed. The slow dynamics of the films, observed by XPCS on the spatial scale of hundreds of nanometers, has an hyper-diffusive character which has been found in many arrested systems. Dynamical heterogeneities have been observed and characterized by means of higher order correlation functions -in particular, four times correlation functions have been experimentally accessed for the first time in an XPCS experiment in the course of this work. The GNPs 2D gel dynamics is characterized by two distinct time scales; both fast and slow motions are confined to the surface plane (2D) and have similar dependencies on the exchanged momentum, and on the coverage fraction. The degree of heterogeneity increases with concentration; at the same time, it seems that the motion involves a hierarchy of spatial scales. These results are compatible with theoretical results and simulations of the dynamics of colloidal gels.Questa Tesi riporta la caratterizzazione della risposta meccanica e della dinamica microscopica di film di Langmuir bidimensionali, eseguita e interpretata nell'ambito del quadro teorico fornito dai teoremi fluttuazione-funzione di risposta. Il modulo meccanico di scorrimento di tali film è stato misurato mediante reologia interfacciale di Shear (ISR). La dinamica microscopica lenta dei campioni è stata caratterizzata tramite misure di spettroscopia di fotocorrelazione di raggi X (XPCS), sia all'interfaccia aria/acqua che su film trasferiti su substrato solido. Sono stati studiati due diversi tipi di sistemi: film polimerici di un poliacrilato fotosensibile contenente azobenzene (PA4), e film di nanoparticelle di oro (GNP) costituenti un gel 2D. I Film di Langmuir di PA4 presentano una risposta di shear elastica, controllabile a piacimento mediante illuminazione con luce UV. Essa induce una fotoisomerizzazione dell'azobenzene che causa il passaggio da un comportamento meccanico elastico ad uno maggiormente viscoso. Questo processo è accompagnato da un'accelerazione, di più di un ordine di grandezza, della dinamica interna, senza che venga modificato alcun parametro termodinamico (temperatura o pressione superficiale). Inoltre, illuminando i film con luce blu si ottiene l'isomerizzazione inversa, paragonabile ad un "quench ottico". Tutto questo permette di portare fuori equilibrio la dinamica interna del polimero in un modo innovativo e anticonvenzionale. I film di GNP sono caratterizzati da una morfologia eterogenea, con una struttura simile a schiuma a basse concentrazioni, e una struttura caratterizzata da distribuzione alla Lévy delle dimensioni caratteristiche alle concentrazioni più elevate. Si ritiene che tale struttura sia all'origine del comportamento di tipo elastico (gel) osservato nella risposta meccanica del sistema. La dinamica lenta del film, osservata mediante XPCS sulla scala spaziale delle centinaia di nanometri, ha un carattere iper-diffusivo, già osservato in molti altri sistemi arrestati. Eterogeneità dinamiche sono stati osservate e caratterizzate mediante funzioni di correlazione di ordine superiore -in particolare, funzioni di correlazione a quattro tempi sono stati misurate sperimentalmente per la prima volta in un esperimento XPCS nel corso di questo lavoro. La dinamica dei gel 2D di GNP è caratterizzata da due scale temporali distinte: entrambi i movimenti (veloci e lenti) sono confinati all'interfaccia (2D) e hanno dipendenze simili in funzione del momento trasferito e della concentrazione. Il grado di eterogeneità aumenta con la concentrazione e, al tempo stesso, sembra che tali moti coinvolgano una gerarchia di scale spaziali. Questi risultati sono compatibili con la teoria e le simulazioni della dinamica di gel colloidali riportate in letteratura

Equilibrium and out-of-equilibrium dynamics in a molecular layer of azopolymer floating on water studied by Interfacial Shear Rheology

We report the details of the construction and calibration of an ultra sensitive surface rheometer, inspired by the setup described in [C.F. Brooks et al Langmuir 15, 2450 (1999)], which makes use of high resolution video tracking of the motion of a floating magnetized needle and is capable of measuring the viscoelastic response of a Langmuir monolayer with an accuracy of 10^-5 N/m. This instrument is then employed for the rheological characterization of a Langmuir monolayer of a photosensitive azobenzene polymer, which can be brought out of equilibrium by a suitable photoperturbation. The complex dynamic shear modulus G= G' + i G" is measured as a function of temperature and illumination power and wavelength. The reversible rheological ch anges induced in the film by photo-perturbation are monitored during time, observing a transition from a predominantly elastic (G' > G'') to a viscoelastic (G' \approx G'') regime. These results are confirmed by comparison with independent measurements performed by us using other rheological techniques. Finally a discussion is made, taking into account the results of a recent x-ray photon correlation spectroscopy experiment on the same polymer in equilibrium and out of equilibrium.Comment: Proceedings of the International Discussion Meeting on Relaxation in Complex Systems, Rome, 2009 12 pages, 7 figure

Particle sizing in non-dilute dispersions using diffusing wave spectroscopy with multiple optical path lengths

Non-dilute dispersed phase systems, such as foams, emulsions, and suspensions, are an important class of final formulations and chemical process intermediates in a variety of industries. The utility of these systems hinges on their stability over the lifetime of use, and therefore an accurate assessment of chemical and physical dynamics, asformulated, is required. We describe a unified treatment of diffusing wave spectroscopy (DWS) data using a range of optical path length with a goniometric instrument. DWS correlation data from multiple angles and robust Monte Carlo simulations are used to determine accurate values of the photon transport mean free path length. The variance on each correlation function is used to determine the physical time range that the mean squared displacement can be analyzed. Using standard solid particle suspensions of polystyrene and SiO2, we determine the average particle size with accuracy comparable to dynamic light scattering

Analysis of bundles and drivers of change of multiple ecosystem services in an Alpine region

Approaches based on the concept of ecosystem services need analyses of the sets of spatially correlated services (i.e. bundles) and of the external factors that modify the ecosystem service supply (i.e. drivers of change). At present, appropriate methods to analyse bundles and drivers of change are still under development. This study proposes a method based on a combination of spatial and statistical analyses to define bundles and to explain the drivers of change of 24 ecosystem services in Trentino, an Alpine region of Italy. Results show that multiple services can be grouped in a few number of bundles with a complex shape. When mapping multiple services across the territory, the spatial units of representation are a combination of the intrinsic units of representation of single ecosystem services and land use classes. Land use management was found as the external factor that causes the greatest variability of the ecosystem services distribution across the region

A Comparative Cost-Benefit Analysis of Conventional and Organic Hazelnuts Production Systems in Center Italy

In this study, the economic profitability of hazelnut production in central Italy using conventional and organic farming systems was evaluated using the cost–benefit analysis methodology. Viterbo’s province is the leading province in Italy in terms of quantity produced. Three indicators were calculated for both farming systems: net present value, payback time, internal rate of return. The analysis was conducted utilizing primary data collected by means of interviews and surveys with local farmers and organizations of producers. The collected production data refer to the decade 2008–2018; a global area of 100.34 ha and 6.14 ha were considered for conventional and organic cultivation, respectively. Sensitivity analysis was carried out considering different discount rates, price variability, and inflation rates. The net present value is equal to 92,800 €/ha and to 3778 €/ha, the payback time is 10.47 years and 42.94 years, while the internal rate of return is 12.2% and 1.1% for the conventional and organic production systems, respectively. The conventional production system performs significantly more remuneratively, considering that the price premium paid by the market for the organic product and the subsidies granted to organic farmers are not sufficient to balance the lower yield

Data-driven Predictive Latency for 5G: A Theoretical and Experimental Analysis Using Network Measurements

The advent of novel 5G services and applications with binding latency requirements and guaranteed Quality of Service (QoS) hastened the need to incorporate autonomous and proactive decision-making in network management procedures. The objective of our study is to provide a thorough analysis of predictive latency within 5G networks by utilizing real-world network data that is accessible to mobile network operators (MNOs). In particular, (i) we present an analytical formulation of the user-plane latency as a Hypoexponential distribution, which is validated by means of a comparative analysis with empirical measurements, and (ii) we conduct experimental results of probabilistic regression, anomaly detection, and predictive forecasting leveraging on emerging domains in Machine Learning (ML), such as Bayesian Learning (BL) and Machine Learning on Graphs (GML). We test our predictive framework using data gathered from scenarios of vehicular mobility, dense-urban traffic, and social gathering events. Our results provide valuable insights into the efficacy of predictive algorithms in practical applications

Biopsy of liver metastasis for women with breast cancer: Impact on survival

Abstract Background Biopsy of metastatic site of disease can influence treatment decisions, but its impact on survival remains uncertain. Patients and methods One-hundred patients with first metachronous liver metastases (LM) from breast cancer (BC) who underwent liver biopsy between 1999 and 2009 were identified. One-hundred matched control patients with LM from BC and no biopsy were selected. Results Liver biopsy had no statistically significant impact on survival when comparing biopsied patients to controls [HR 0.82 (95% CI 0.58–1.16)]. Patients with early metastasis (within 3 years) undergoing liver biopsy had a better survival [HR 0.60 (95% CI 0.38–0.97)] compared to those who did not. Liver biopsy had no statistically significant impact on survival in patients with late LM (after 3 years) [HR 1.09 (95% CI 0.69–1.74)]. We observed that 18 out of 100 biopsied patients (18.0%) had a conversion of predictive factors which allowed adjusting for therapy, specifically new expression of ER ( n = 5), overexpression of HER2 ( n = 12) or both ( n = 1). Fourteen out of 18 (77.8%) received anti-HER2 treatment for the first time at the time of metastasis and 3 others (16.7%) received hormone therapy. Those 18 patients showed a better survival compared to the other 82 biopsied patients [HR 0.55 (95% CI 0.28–1.10)] and compared to the 13 biopsied patients with disappearance of features which predicted responsiveness to a given treatment [HR 0.19 (95% CI 0.06–0.62)]. Conclusions Liver biopsy can impact survival of patients with early metastases from BC. Discordance between primary and distant lesions can offer the patients new treatment options