Vlasov simulation of laser-driven shock acceleration and ion turbulence

We present a Vlasov, i.e. a kinetic Eulerian simulation study of nonlinear collisionless ion-acoustic shocks and solitons excited by an intense laser interacting with an overdense plasma. The use of the Vlasov code avoids problems with low particle statistics and allows a validation of particle-in-cell results. A simple original correction to the splitting method for the numerical integration of the Vlasov equation has been implemented in order to ensure the charge conservation in the relativistic regime. We show that the ion distribution is affected by the development of a turbulence driven by the relativistic "fast" electron bunches generated at the laser-plasma interaction surface. This leads to the onset of ion reflection at the shock front in an initially cold plasma where only soliton solutions without ion reflection are expected to propagate. We give a simple analytic model to describe the onset of the turbulence as a nonlinear coupling of the ion density with the fast electron currents, taking the pulsed nature of the relativistic electron bunches into account

Social responsibility reporting at group level in a mutual insurance company: the experience of ITAS Mutua Assicurazioni

The Global Reporting Initiative (GRI) guidelines state that a social responsibility re-port should provide information about 'all entities over which the reporting organisa-tion exercises control or significant influence'. A mutual insurance company which sells products through a network of insurance agents has to provide information about insurance agencies and about customers. ITAS is the first company to produce a so-cial responsibility report including data provided by the network of insurance agents, the customers and the shareholders. The paper illustrates the process used to collect and process information. Interestingly, the data collection process opened a channel of communication with both agents and customers/shareholders supplying ITAS with useful suggestions from the strategic and marketing point of view

Studio e progetto di sistema per la misura della velocità in veicoli

La misura della velocità in un veicolo, rispetto al riferimento rappresentato dal terreno, è generalmente ricavata dalla misura della velocità di rotazione delle ruote, utilizzando vari tipi di sensori (magnetici, ottici ecc) applicati direttamente alle ruote o su organi meccanici rigidamente collegati alle ruote stesse. Quello che interessa conoscere è la velocità del mezzo rispetto al terreno: il modello fisico che descrive il sistema terreno-ruota ha dei parametri che hanno una certa varianza rispetto al loro valor medio conosciuto (si pensi alle tolleranze di lavorazione) e inoltre è tempovariante sia nel lungo periodo (mesi), sia nel medio periodo (ore), che nel breve periodo (secondi): si pensi alle usure dei pneumatici, al cambiamento della loro pressione con la temperatura o addirittura al caso di slittamento fra ruota e terreno. La misura della velocità rispetto al terreno (detta comunemente TSOG, True Speed Over Ground) è utile anche per rilevare se, e di quanto, una ruota stia muovendosi slittando. Pertanto argomento di questa tesi sarà quello di studiare un sistema di misura della velocità che non utilizzi un contatto fra il mezzo di cui si vuol misurare la velocità e il terreno (un sistema di misura siffatto è detto “contactless”), realizzato inoltre con componentistica idonea a ottenere un sistema di basso costo

«Da la cuna a la tomba è un breve passo»: una lettura di due "rime morali" di Marino

In queste pagine si intende rivolgere lo sguardo alle scaturigini dellapoesia sacra mariniana, in particolare alle Rime morali contenute delle Rime del1602. Attraverso la lettura di due tessere esemplari, si propone un’indagine chedelinei alcune costanti della poesia morale del giovane Marino. Nell’analisi sicontestualizzano i testi all’interno del panorama letterario dell’epoca e della tradizioneclassica del genere morale, mettendo in luce, oltre alla disinvoltura nel riusoe nell’intarsio delle fonti, il grado d’innovazione dell’operazione mariniana

Collaboration between a human group and artificial intelligence can improve prediction of multiple sclerosis course. A proof-of-principle study

Background: Multiple sclerosis has an extremely variable natural course. In most patients, disease starts with a relapsing-remitting (RR) phase, which proceeds to a secondary progressive (SP) form. The duration of the RR phase is hard to predict, and to date predictions on the rate of disease progression remain suboptimal. This limits the opportunity to tailor therapy on an individual patient's prognosis, in spite of the choice of several therapeutic options. Approaches to improve clinical decisions, such as collective intelligence of human groups and machine learning algorithms are widely investigated. Methods: Medical students and a machine learning algorithm predicted the course of disease on the basis of randomly chosen clinical records of patients that attended at the Multiple Sclerosis service of Sant'Andrea hospital in Rome. Results: A significant improvement of predictive ability was obtained when predictions were combined with a weight that depends on the consistence of human (or algorithm) forecasts on a given clinical record. Conclusions: In this work we present proof-of-principle that human-machine hybrid predictions yield better prognoses than machine learning algorithms or groups of humans alone. To strengthen this preliminary result, we propose a crowdsourcing initiative to collect prognoses by physicians on an expanded set of patients

Direct Algebraic Restoration of Slavnov-Taylor Identities in the Abelian Higgs-Kibble Model

A purely algebraic method is devised in order to recover Slavnov-Taylor identities (STI), broken by intermediate renormalization. The counterterms are evaluated order by order in terms of finite amplitudes computed at zero external momenta. The evaluation of the breaking terms of the STI is avoided and their validity is imposed directly on the vertex functional. The method is applied to the abelian Higgs-Kibble model. An explicit mass term for the gauge field is introduced, in order to check the relevance of nilpotency. We show that, since there are no anomalies, the imposition of the STI turns out to be equivalent to the solution of a linear problem. The presence of ST invariants implies that there are many possible solutions, corresponding to different normalization conditions. Moreover, we find more equations than unknowns (over-determined problem). This leads us to the consideration of consistency conditions, that must be obeyed if the restoration of STI is possible.Comment: 10 pages, Latex and packages amsfonts, amssymb and amsth

Improving the Protectiveness of 3-Mercaptopropyl-Trimethoxysilane Coatings on Bronze by Addition of Oxidic Nano- and Microparticles

The protectiveness of coatings based on 3-mercaptopropyl-trimethoxysilane (PropS-SH) applied on bronze artworks was enhanced by investigating and tuning a variety of factors. In particular, the coating performances were optimized by proper additive choice among oxide nanoparticles (CeO2, La2O3, TiO2) and microparticles (fly ash (FA)), and by varying the aging time of the nanoparticle suspensions before coating application and the RT curing time of the coatings. Moreover, the possibility of conservation of the silane solution under refrigerated conditions was assessed. The aggressive environment was a tenfold concentrated synthetic acid rain (AR × 10). The techniques adopted comprised electrochemical tests (polarization curve recording and EIS tests) and SEM-Energy Dispersion Spectroscopy (EDS) observations. In the case of FA microparticles, never used before as additives in silane coatings, further tests were performed in FA suspensions in AR × 10 to clarify the contribution of these particles to PropS-SH coating protectiveness. The tests included pH measurements, elemental chemical analyses, and electrochemical tests on bare bronze. Improved performances of PropS-SH coatings were achieved by La2O3, CeO2, and FA addition, with La2O3 affording the best results during 20 days of immersion. The positive influence of FA was connected to its alkaline character and to the release of soluble silicates

Dimensionality and Summary Measures of the SF-36 v1.6: Comparison of Scale- and Item-Based Approach Across ECRHS II Adults Population

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Italian Radiology's Response to the COVID-19 Outbreak

No abstract availabl