Fault-Tolerant Adaptive Parallel and Distributed Simulation

Discrete Event Simulation is a widely used technique that is used to model and analyze complex systems in many fields of science and engineering. The increasingly large size of simulation models poses a serious computational challenge, since the time needed to run a simulation can be prohibitively large. For this reason, Parallel and Distributes Simulation techniques have been proposed to take advantage of multiple execution units which are found in multicore processors, cluster of workstations or HPC systems. The current generation of HPC systems includes hundreds of thousands of computing nodes and a vast amount of ancillary components. Despite improvements in manufacturing processes, failures of some components are frequent, and the situation will get worse as larger systems are built. In this paper we describe FT-GAIA, a software-based fault-tolerant extension of the GAIA/ART\`IS parallel simulation middleware. FT-GAIA transparently replicates simulation entities and distributes them on multiple execution nodes. This allows the simulation to tolerate crash-failures of computing nodes; furthermore, FT-GAIA offers some protection against byzantine failures since synchronization messages are replicated as well, so that the receiving entity can identify and discard corrupted messages. We provide an experimental evaluation of FT-GAIA on a running prototype. Results show that a high degree of fault tolerance can be achieved, at the cost of a moderate increase in the computational load of the execution units.Comment: Proceedings of the IEEE/ACM International Symposium on Distributed Simulation and Real Time Applications (DS-RT 2016

Radiation Hardness and Defects Activity in PEA2PbBr4 Single Crystals

Metal halide perovskites (MHPs) are low-temperature processable hybrid semiconductor materials with exceptional performances that are revolutionizing the field of optoelectronic devices. Despite their great potential, commercial deployment is hindered by MHPs lack of stability and durability, mainly attributed to ions migration and chemical interactions with the device electrodes. To address these issues, 2D layered MHPs have been investigated as possible device interlayers or active material substitutes to reduce ion migration and improve stability. Here we consider the 2D perovskite PEA2PbBr4 that was recently discussed as very promising candidate for X-ray direct detection. While the increased resilience of PEA2PbBr4 detectors have already been reported, the physical mechanisms responsible for such improvement compared to the standard "3D" perovskites are not still fully understood. To unravel the charge transport process in PEA2PbBr4 crystals thought to underly the device better performance, we adapted an investigation technique previously used on highly resistive inorganic semiconductors, called photo induced current transient spectroscopy (PICTS). We demonstrate that PICTS can detect three distinct trap states (T1, T2, and T3) with different activation energies, and that the trap states evolution upon X-ray exposure can explain PEA2PbBr4 superior radiation tolerance and reduced aging effects. Overall, our results provide essential insights into the stability and electrical characteristics of 2D perovskites and their potential application as reliable and direct X-ray detectors

Critical storm thresholds for significant morphological changes and damage along the Emilia-Romagna coastline, Italy

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European code against cancer 4th edition: 12 ways to reduce your cancer risk

This overview describes the principles of the 4th edition of the European Code against Cancer and provides an introduction to the 12 recommendations to reduce cancer risk. Among the 504.6 million inhabitants of the member states of the European Union (EU28), there are annually 2.64 million new cancer cases and 1.28 million deaths from cancer. It is estimated that this cancer burden could be reduced by up to one half if scientific knowledge on causes of cancer could be translated into successful prevention. The Code is a preventive tool aimed to reduce the cancer burden by informing people how to avoid or reduce carcinogenic exposures, adopt behaviours to reduce the cancer risk, or to participate in organised intervention programmes. The Code should also form a base to guide national health policies in cancer prevention. The 12 recommendations are: not smoking or using other tobacco products; avoiding second-hand smoke; being a healthy body weight; encouraging physical activity; having a healthy diet; limiting alcohol consumption, with not drinking alcohol being better for cancer prevention; avoiding too much exposure to ultraviolet radiation; avoiding cancer-causing agents at the workplace; reducing exposure to high levels of radon; encouraging breastfeeding; limiting the use of hormone replacement therapy; participating in organised vaccination programmes against hepatitis B for newborns and human papillomavirus for girls; and participating in organised screening programmes for bowel cancer, breast cancer, and cervical cancer

Fault-Tolerant Adaptive Parallel and Distributed Simulation

Discrete Event Simulation is a widely used technique that is used to model and analyze complex systems in many fields of science and engineering. The increasingly large size of simulation models poses a serious computational challenge, since the time needed to run a simulation can be prohibitively large. For this reason, Parallel and Distributes Simulation techniques have been proposed to take advantage of multiple execution units which are found in multicore processors, cluster of workstations or HPC systems. The current generation of HPC systems includes hundreds of thousands of computing nodes and a vast amount of ancillary components. Despite improvements in manufacturing processes, failures of some components are frequent, and the situation will get worse as larger systems are built. In this paper we describe FT-GAIA, a software-based fault-tolerant extension of the GAIA/ARTIS parallel simulation middleware. FT-GAIA transparently replicates simulation entities and distributes them on multiple execution nodes. This allows the simulation to tolerate crash-failures of computing nodes, furthermore, FT-GAIA offers some protection against Byzantine failures since synchronization messages are replicated as well, so that the receiving entity can identify and discard corrupted messages. We provide an experimental evaluation of FT-GAIA on a running prototype. Results show that a high degree of fault tolerance can be achieved, at the cost of a moderate increase in the computational load of the execution units

I nuovi studi su marreggiate e fenomeni erosivi

Negli ultimi anni è cresciuta l'attenzione per il monitoraggio dei fenomeni a forte impatto sul sistema costiero. Il progetto europeo Micore prevede lo sviluppo di un sistema previsionale per la comprensione e previsione dei fenomeni erosivi sulla costa anche in Emilia-Romagna. I risultati per l'inverno 2009-2010 hanno evidenziato il contributo delle acque alte per i fenomeni erosivi e hanno confermato la necessità di un sistema di previsione attivo e di continuare le pratiche di protezione in atto

AN EARLY WARNING SYSTEM FOR THE ON-LINE PREDICTION OF COASTAL STORM RISK ON THE ITALIAN COASTLINE

The ability to predict the imminent arrival of coastal storm risks is a valuable tool for civil protection agencies in order to prepare themselves and, if needs be, execute the appropriate hazard-reduction measures. In this study we present a prototype Early Warning System (EWS) for coastal storm risk on the Emilia-Romagna coastline in Northern Italy. This EWS is run by executing a chain of numerical models (SWAN, ROMS and XBeach) daily, with the final output transformed into a format suitable for decision making by end-users. The storm impact indicator selected for this site is the Safe Corridor Width (SCW), which is a measure of how much dry beach width is available for safe passage by beach users. A three-day time-series of the predicted SCW is generated daily by the prototype EWS. If the minimum SCW exceeds a certain threshold, a warning is issued to end-users via an automated email service. All available prediction information is also updated daily on-line. Over the one year that the EWS has been operating (June 2011 until June 2012), 13 "code red† and 16 "code orange† warnings have been issued, with the remaining 305 predictions indicating low hazard in terms of the SCW. The reliability of the predictions from the perspective of the end-user has meant that the EWS is currently being expanded to include the entire Emilia-Romagna coastline

Cyanobuta-1,3-dienes as Novel Electron Acceptors for Photoactive Multicomponent Systems

The synthesis, electrochemical, and photophysical properties of five multicomponent systems featuring a ZnII porphyrin (ZnP) linked to one or two anilino donor-substituted pentacyano- (PCBD) or tetracyanobuta-1,3- dienes (TCBD), with and without an interchromophoric bridging spacer (S), are reported: ZnP-S-PCBD (1), ZnP-S-TCBD (2), ZnP-TCBD (3), ZnP-(S-PCBD)2 (4), and ZnP-(S-TCBD)2 (5). By means of steady-state and time-resolved absorption and luminescence spectroscopy (RT and 77 K), photoinduced intramolecular energy and electron transfer processes are evidenced, upon excitation of the porphyrin unit. In systems equipped with the strongest acceptor PCBD and the spacer (1, 4), no evidence of electron transfer is found in toluene, suggesting ZnP→PCBD energy transfer, followed by ultrafast (<10 ps) intrinsic deactivation of the PCBD moiety. In the analogous systems with the weaker acceptor TCBD (2, 5), photoinduced electron transfer occurs in benzonitrile, generating a charge-separated (CS) state lasting 2.3 μs. Such a long lifetime, in light of the high Gibbs free energy for charge recombination (ΔGCR=-1.39 eV), suggests a back-electron transfer process occurring in the so-called Marcus inverted region. Notably, in system 3 lacking the interchromophoric spacer, photoinduced charge separation followed by charge recombination occur within 20 ps. This is a consequence of the close vicinity of the donor-acceptor partners and of a virtually activationless electron transfer process. These results indicate that the strongly electron-accepting cyanobuta-1,3-dienes might become promising alternatives to quinone-, perylenediimide-, and fullerene-derived acceptors in multicomponent modules featuring photoinduced electron transfer. Catch the electron: Strongly electron-accepting multicyanobuta-1,3-dienes provide a new class of electron acceptors for incorporation into photoactive multicomponent systems. Photophysical and electrochemical investigations revealed photoinduced intramolecular electron transfer (PET) from a ZnII porphyrin to 1,1,4,4-tetracyanobuta-1,3-diene acceptor sites appended by an insulating spacer, with a long-lived charge-separated excited state of 2.3 μs in benzonitrile. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim