Studio e realizzazione di un protocollo di compressione dati per reti di sensori sismici

Abstract Permanent seismic network management, in a country defined by active volcanoes, as well as a tectonic faults network, involve evaluating a great number of working and efficiency parameters, especially when risks are of a different nature and can cause economic damage to the local region. One example is the Permanent Seismic Net managed by the Istituto Nazionale di Geofisica e Vulcanologia(INGV), Catania Section, in Italy, which comprises about sixty seismic stations, using analogical and digital technology, located around Mt. Etna, the Peloritani and Hyblean areas, southern Calabria and in the Aeolian archipelago. Digital technology enables increasing management performance, signal to noise ratio and firmness, allowing gradual upgrades from analogical to digital stations. On the other hand, it introduces some new problems such as the small capacity of the transmission channel (available bandwidth), which is hard to manage and causes data acquisition delays. The seismic signals, in particular, after digitization, are compressed to make better use of the available channel. The use of a lossless compression algorithm causes variable efficiency that depends, generally, on the kind of signal to compress. We know that signals that change frequently in a time window, and that have a high RMS amplitude, are more difficult to compress with lossless compression, and hence need more bandwidth. Instead, signals with a low RMS amplitude and that change little in a time window, are better compressed with lossless compression and require smaller space channels. Various active volcanic phenomenology in eruption phases, could cause a big variation in some seismic signal parameters like RMS amplitude, this variation causes channel bandwidth consumption increase. This implies an efficiency evaluation of the Nanometrics® transmission protocol and compression algorithm used by the remote station instruments, especially in critical stages as when a volcano is preparing to erupt. Alternative protocols are proposed to increase the global evaluation quality of the Nanometrics® protocol and compression algorithm used by the RSP instrumentation. Comparisons between solutions are made by studying the relationship between seismic signal RMS amplitude and its bandwidth consumption. Studying the compression algorithm and researching potential optimization, helps build a plausible evaluation of the bandwidth needed in the critical stages that are typical in active volcanoes like Etna

Expression and signal transduction of the glucagon receptor in βTC3 cells

AbstractThe expression and signal transduction of the glucagon receptor (GR) have been studied in βTC3 cells. Northern blot and RT-PCR analysis indicated the expression of the GR gene in βTC3 cells. One-5 nM glucagon stimulated a 2.5-fold increase in the IPs production. At glucagon concentrations higher than 5 nM, the production of IPs was blunted but not abolished. The accumulation of intracellular cAMP was observed following the stimulation with 5 nM of glucagon. A maximal 4.5-fold increase in cAMP was observed using 250 nM glucagon and higher. Comparative studies using a glucagon anatogonist, des-His1[Glu]9glucagon, showed no effect on intracellular cAMP and IPs in βTC3 cells. Our data shows that the GR gene is expressed in βTC3 cells. The GR in βTC3 cells transmits its intracellular signal by causing the accumulation of both IPs and cAMP

Neuroprotective potential of isothiocyanates in an in vitro model of neuroinflammation

Isothiocyanates (ITCs), present as glucosinolate precursors in cruciferous vegetables, have shown anti-inflammatory, antioxidant and anticarcinogenic activities. Here, we compared the effects of three different ITCs on ROS production and on the expression of matrix metalloproteinase (MMP)-2 and -9, which represent important pathogenetic factors of various neurological diseases. Primary cultures of rat astrocytes were activated by LPS and simultaneously treated with different doses of Allyl isothiocyanate (AITC), 2-Phenethyl isothiocyanate (PEITC) and 2-Sulforaphane (SFN). Results showed that SFN and PEITC were able to counteract ROS production induced by H2O2. The zymographic analysis of cell culture supernatants evidenced that PEITC and SFN were the most effective inhibitors of MMP-9, whereas, only SFN significantly inhibited MMP-2 activity. PCR analysis showed that all the ITCs used significantly inhibited both MMP-2 and MMP-9 expression. The investigation on the mitogen-activated protein kinase (MAPK) signaling pathway demonstrated that ITCs modulate MMP transcription by inhibition of extracellular-regulated protein kinase (ERK) activity. Results of this study suggest that ITCs could be promising nutraceutical agents for the prevention and complementary treatment of neurological diseases associated with MMP involvement

Installazione di un radiometro nell'area sommitale del vulcano Etna

Le tecniche di telerilevamento satellitare e da terra per la stima della temperatura di anomalie termiche delle superfici vulcaniche, della loro variazione nel tempo e per individuare attività parossistiche o l’inizio di una fase di colate di lava, sono ormai entrate a far parte della sorveglianza e del monitoraggio vulcanologico [es. Francis, 1979; Geraci et al., 1985; Lombardo et al., 2011; Spampinato et al., 2011]. I sensori in una banda spettrale dell’infrarosso quali radiometri e telecamere termiche, utilizzati in prossimità di bocche eruttive, hanno fornito cospicue quantità di dati di temperatura della superficie di corpi magmatici (colate laviche, laghi di lava, duomi lavici), plume vulcanici, fumarole, registrati a distanza di totale sicurezza [Spampinato et al., 2011]. In particolare, i radiometri, sia portatili che installati in stazioni permanenti, oltre che fornire dati da confrontare con misure geochimiche, permettono l’acquisizione di dati di temperatura ad elevata frequenza, tali da essere messi in relazione con le misure derivate da osservazioni geofisiche quali ad esempio il tremore sismico [es. Harris e Ripepe, 2007; Branan et al., 2008].In questo lavoro si descrivono i dettagli dell’installazione di una stazione radiometrica collocata nell’area sommitale dell’Etna in zona Belvedere, nel sito già utilizzato da una stazione multiparametrica (con sensori sismici e infrasonici) e denominato EBEL. Si descrivono anche la metodologia di trasmissione dati in continuo, il trattamento del dato convertito in temperatura apparente nel campo di vista del radiometro, la visualizzazione in tempo quasi reale del dato e la sua diffusione tramite WEB

Conduction band spin splitting and negative magnetoresistance in A3B5{\rm A}_3{\rm B}_5 heterostructures

The quantum interference corrections to the conductivity are calculated for an electron gas in asymmetric quantum wells in a magnetic field. The theory takes into account two different types of the spin splitting of the conduction band: the Dresselhaus terms, both linear and cubic in the wave vector, and the Rashba term, linear in wave vector. It is shown that the contributions of these terms into magnetoconductivity are not additive, as it was traditionally assumed. While the contributions of all terms of the conduction band splitting into the D'yakonov--Perel' spin relaxation rate are additive, in the conductivity the two linear terms cancel each other, and, when they are equal, in the absence of the cubic terms the conduction band spin splitting does not show up in the magnetoconductivity at all. The theory agrees very well with experimental results and enables one to determine experimentally parameters of the spin-orbit splitting of the conduction band.Comment: 8 pages, RevTeX, 4 Postscript figure