Numerical studies on semi-implicit and implicit methods for reaction-diffusion equations

In this report Rosenbrock, extended and generalized trapezoidal formulae are considered. Numerical studies on these methods have been developed on a linear and a nonlinear reaction diffusion convection equation

La centralità delle risorse umane ed il ruolo della formazione: il caso Unicoop Firenze

L’elaborato si propone di analizzare la rilevanza strategica delle risorse umane come variabile economica critica per le aziende che a differenza delle risorse materiali e finanziarie, possedute nella stessa quantità e qualità dai concorrenti rappresenta una risorsa unica ed inimitabile. Viene evidenziato inoltre come il tradizionale processo di valutazione delle risorse umane possa essere anacronistico, poiché le aziende temporeggiano in attesa dei risultati prima di intervenire i quali però sono indicatori ritardati e registrano il passato. Si sostiene invece, che prendendo in considerazione la formazione come strumento di valutazione delle risorse umane si può riuscire a fronteggiare tale inconveniente passando così ad un controllo antecedente dei comportamenti. La centralità delle risorse umane ed il ruolo della formazione sono stati indagati in Unicoop Firenze

low noise design experience for the skads best demonstrator

The experience gained in both the design and testing of low noise amplifiers for the SKADS/BEST demonstrator, is here described. Different architectures (single ended, balanced and differential) have been investigated and compared in order to fulfill the BEST goals and, in general, the main SKA related technology requirements: low cost, high performances and reliability. This experience is leading to the design of front ends suitable for low frequency SKA pathfinders and other applications

Controlling Rayleigh-Backscattering-Induced Distortion in Radio over Fiber Systems for Radioastronomic Applications

Radio over Fiber (RoF) Systems exploiting a direct modulation of the laser source are presently utilized within important Radioastronomic scenarios. Due to the particular operating conditions of some of these realizations, the phenomena which typically generate nonlinearities in RoF links for telecommunications applications can be here regarded as substantially harmless. However, these same operating conditions can make the RoF systems vulnerable to different kinds of nonlinear effects, related to the influence of the Rayleigh Backscattered signal on the transmitted one. A rigorous description of the phenomenon is performed, and an effective countermeasure to the problem is proposed and demonstrated, both theoretically and experimentally.Comment: Accepted for publication in IEEE/OSA Journal of Lightwave Technolog

Governing a Pandemic: Assessing the role of collaboration on Latin American responses to the COVID-19 crisis

How do governments address complex, cross-sectoral problems, like the COVID-19 pandemic? Why were some Latin American countries more successful at containing the pandemic´s most devastating health outcomes? We argue that national governments that were more collaborative in their response to COVID-19 were more successful in reducing death rates. Our original dataset offers a novel attempt to operationalise collaborative governance (CG). We undertake simple statistical tests to measure the relationship between CG and COVID-19-related mortality rates in Latin America. We then choose three case studies to assess whether collaboration was meaningful in practice. Initial evidence suggests governments that pursued CG were more effective at containing mortality rates early on in the pandemic. The collaboration helped to foster cooperation over resources; buy time to prepare for a potential case surge; and produce a unified message regarding what citizens should do to prevent viral spread.Fil: Cyr, Jennifer. Universidad Torcuato Di Tella. Departamento de Ciencia Política y Estudios Internacionales; ArgentinaFil: Bianchi, Matías Federico. University of Arizona; Estados Unidos. University of Arizona; Estados UnidosFil: Gonzalez, Lucas Isaac. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Perini, Antonella. University of Oxford; Reino Unid

Monitoring toxic Ostreopsis cf. ovata in recreational waters using a qPCR assay.

Ostreopsis sp. is a toxic marine benthic dinoflagellate that causes high biomass blooms, posing a threat to human health, marine biota and aquaculture activities, and negatively impacting coastal seawater quality. Species-specific identification and enumeration is fundamental because it can allow the implementation of all the necessary preventive measures to properly manage Ostreopsis spp. bloom events in recreational waters and aquaculture farms. The aim of this study was to apply a rapid and sensitive qPCR method to quantify Ostreopsis cf. ovata abundance in environmental samples collected from Mediterranean coastal sites and to develop site-specific environmental standard curves. Similar PCR efficiencies of plasmid and environmental standard curves allowed us to estimate the LSU rDNA copy number per cell. Moreover, we assessed the effectiveness of mitochondrial COI and cob genes as alternative molecular markers to ribosomal genes in qPCR assays for Ostreopsis spp. quantification

Optimal Dithering Configuration Mitigating Rayleigh-Backscattering-Induced Distortion in Radioastronomic Optical Fiber Systems

In the context of Radioastronomic applications where the Analog Radio-over-Fiber technology is used for the antenna downlink, detrimental nonlinearity effects arise because of the interference between the forward signal generated by the laser and the Rayleigh backscattered one which is re-forwarded by the laser itself toward the photodetector. The adoption of the so called dithering technique, which involves the direct modulation of the laser with a sinusoidal tone and takes advantage of the laser chirping phenomenon, has been proved to reduce such Rayleigh Back Scattering - induced nonlinearities. The frequency and the amplitude of the dithering tone should both be as low as possible, in order to avoid undesired collateral effects on the received spectrum as well as keep at low levels the global energy consumption. Through a comprehensive analysis of dithered Radio over Fiber systems, it is demonstrated that a progressive reduction of the dithering tone frequency affects in a peculiar fashion both the chirping characteristics of the field emitted by the laser and the spectrum pattern of the received signal at the fiber end. Accounting for the concurrent effects caused by such phenomena, optimal operating conditions are identified for the implementation of the dithering tone technique in radioastronomic systems.Comment: 11 pages. Accepted for Journal of Lightwave Technolog

Cina e made in italy: le esperienze del stema imprenditoriale marchigiano

“CINA E MADE IN ITALY: le esperienze del sistema imprenditoriale marchigiano” raccoglie le testimonianze di istituzioni, enti, imprese del territorio marchigiano, che hanno intrapreso iniziative e progetti di cooperazione e internazionalizzazione con la Cina ed i paesi asiatici e i contributi di ricercatori ed esperti che, da differenti punti di osservazione, stanno da tempo studiando il “fenomeno Cina”. I contributi dei diversi autori consentono di aprire e avviare una riflessione sul ruolo che la ricerca nel settore del design potrebbe svolgere come reale supporto alla capacità d’innovazione del Sistema Marche nella competizione globale

Radio frequency over fiber technology for SKA-low receiver

The signal reception chain is an essential element for achieving the square kilometer array-low (SKA-low) system requirements in terms of high sensitivity and dynamic range. The balance between gain, linearity, and low power consumption, as well as the cost, are fundamental parameters that influence the selection of the most suitable technology for SKA-low. Further factors, such as low self-generated radio frequency (RF) interference, high reliability, robustness under extreme environment, and last but not least, the distance between the antennas and the acquisition systems, have impacts on the selection for both architecture and receiver system design. The selected technology for the SKA-low RF signal transportation is RF-over-fiber systems, where the preamplified RF signal picked up by the antennas is carried via analogue modulation over optical fiber. The rationales behind the selection are reported, along with descriptions on the development of the receiver prototypes. The prototypes were deployed and installed on the demonstrator arrays at the selected SKA-low site in Western Australian. Particular attention has been put on the thermal characterization of the receiver system under the actual operating temperature on site, especially when both transmitting part and the optical medium are subjected to external ambient temperature variations. Performance issues encountered in the demonstrator arrays are also discussed along with some proposals for future activities

test and measurements of reliability performance on radioreceiver chains for the northern cross radio telescope

Reliability analysis of two radioreceiver chains architecture were performed in order to choose the solution with the highest value of Mean Time Between Failures and minimize faults in the system, with the consequent lower maintenance costs. Located the most stressed devices from a climatic-environmental point of view, we decided to monitor their real thermal solicitation in order to evaluate the proper reliability performances varying temperature and the possible degradation of the critical subsystem and consequently of the entire chain. The design for reliability approach proposed in this research for the reinstrumentation of the Northern Cross Radiotelescope could be an useful aid for the design of the international SKA Telescope. Since it will be extremely large (1 square kilometre) the maintenance costs, related to the reliability, become an important parameter to evaluate. This research activity was developed in partnership with the Istituto di Radioastronomia, Istituto Nazionale di Astrofisica, in the context of the Square Kilometer Array Design Study supported by UE FP6