Remote monitoring of natural slopes. Insights from the first Terrestrial INSAR campaign In Vietnam

Il presente lavoro, realizzato nell'ambito di un progetto di ricerca finanziato dal Vietnamese Space Science & Technology Program, mostra i primi risultati di una campagna di monitoraggio da remoto della frana di Nam Dan (Vietnam settentrionale) dove, per la prima volta nel Paese, è stata utilizzata la tecnica dell'Interferometria SAR Terrestre (TInSAR). Tale tecnica si basa sull’utilizzo di un sensore radar installato su una piattaforma terrestre che trasmette il segnale nel campo delle microonde (banda Ku) e ne riceve gli echi di ritorno dai target riflettenti. Il sensore utilizzato è costituito da due antenne (una trasmittente e una ricevente) e si muove seguendo una traiettoria lineare lungo un binario. Grazie a questa tecnica è possibile effettuare da remoto il monitoraggio delle deformazioni del terreno, raggiungendo una precisione sub-millimetrica in condizioni ideali (ad es. breve distanza, alta riflettività, etc.). Le attività di monitoraggio sono state condotte nel villaggio di Nam Dan, dove una frana attiva con diverse evidenze geomorfologiche quali scarpate, crepe, contropendenze con ristagni d’acqua, abitazioni e beni pubblici gravemente danneggiati, costituisce una seria minaccia per la popolazione locale. L’area di Nam Dan (22°36'N; 104°29'E) si trova nella parte meridionale del distretto di Xin Man, in prossimità del confine tra Vietnam e Cina. Tale distretto, caratterizzato da un clima monsonico umido subtropicale, si estende su un'area di circa 582 km2ed è caratterizzato da una topografia complessa con catene montuose, pendii terrazzati e valli molto profonde con processi erosivi avanzati. Gli archivi locali riportano che in tale area, dal 2012 al 2016, si sono verificate 967 frane, principalmente durante l'estate in corrispondenza delle piogge monsoniche del sud-ovest. Secondo recenti indagini e osservazioni sul campo, la frana oggetto di studio, verificatasi nel luglio del 2012 in seguito a forti precipitazioni, può classificarsi come uno scivolamento traslativo di detrito e si estende su un'area di circa 12.000 m2 con una profondità media di circa 22,5 metri. Nell'agosto del 2013 la frana ha causato nuovi gravi danni a 5 abitazioni, al mercato comunale e alla strada provinciale n. 178 e rappresenta tutt’oggi un grave pericolo per la popolazione residente. Le attività di monitoraggio sono state effettuate tra agosto e dicembre 2019 attraverso un nuovo interferometro radar denominato Phoenix, che è stato utilizzato in una delle sue prime applicazioni sul campo. Il monitoraggio tramite Interferometria SAR Terrestre ha avuto l’obiettivo di controllare l’evoluzione del versante instabile ed ha portato alla realizzazione di mappe di spostamento e delle relative serie temporali, fornendo informazioni dettagliate sulla localizzazione e sui tassi di deformazione dei processi gravitativi di versante presenti. Sebbene nel periodo monitorato non siano state registrate deformazioni significative, l'utilizzo di questa tecnica di telerilevamento, insieme alla strumentazione a contatto precedentemente installata (inclinometri, piezometri, pluviometri) ed alle indagini sul campo, hanno contribuito a migliorare la conoscenza della frana di Nam Dan e la comprensione del suo cinematismo, con particolare riguardo all'evoluzione temporale delle deformazioni superficiali, anche tenendo conto delle condizioni meteorologiche locali. I risultati ottenuti durante la campagna di monitoraggio, in combinazione con i dati precedentemente acquisiti ed elaborati, confermano che il versante oggetto di studio è caratterizzato da fenomeni di instabilità gravitativa, che possono essere innescati da precipitazioni intense che solitamente avvengono nell’area durante la stagione estiva. In considerazione dei contesti ambientali dell'area, quali le severe condizioni climatiche e le aree impervie da percorrere in assenza di infrastrutture viarie adeguate, è stato posto l'accento sulle attività operative sul campo e sull'individuazione di soluzioni tecnologiche appropriate, che hanno rappresentato aspetti particolarmente sfidanti per il monitoraggio di fenomeni franosi tramite tecniche di telerilevamento.The present work, realized in the framework of a research project funded by the Vietnamese Space Science & Technology Program, shows the first insights of remote monitoring at the Nam Dan landslide (Northern Vietnam). The Terrestrial SAR Interferometry (TInSAR) technique was used for the first time in the Country.The activities were performed in Nam Dan village, where an active landslide with several geomorphological evidences as open cracks and scarps, severely damaged dwellings and public assets, constituting a serious hazard to the local inhabitants. The monitoring activities were carried out between August and December 2019 through a new TInSAR device called Phoenix which it was used for one of its first on-field applications. The Terrestrial SAR was aimed at creating displacement maps and related time series, providing detailed information on the location and deformation rate of the processes under investigation. The use of such a remote sensing technique, coupled with contact instrumentation (inclinometers, piezometers, rain gauge) and field surveys have contributed to improving the knowledge about the Nam Dan landslide and the understanding of its behaviour, with particular regard to the time evolution of deformations

Energy-efficient full-range oscillation analysis of parallel-plate electrostatically actuated MEMS resonators

This is the peer reviewed version of the following article: “Fargas Marques, A., Costa Castelló, R. (2017) Energy-efficient full-range oscillation analysis of parallel-plate electrostatically actuated MEMS resonators, 1-13.” which has been published in final form at [doi: 10.1007/s11071-017-3633-8]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."Electrostatic parallel-plate actuators are a common way of actuating microelectromechanical systems, both statically and dynamically. Nevertheless, actuation voltages and oscillations are limited by the nonlinearity of the actuator that leads to the pull-in phenomena. This work presents a new approach to obtain the electrostatic parallel-plate actuation voltage, which allows to freely select the desired frequency and amplitude of oscillation. Harmonic Balance analysis is used to determine the needed actuation voltage and to choose the most energy-efficient actuation frequency. Moreover, a new two-sided actuation approach is presented that allows to actuate the device in all the stable range using the Harmonic Balance Voltage.Peer ReviewedPostprint (author's final draft

Complete genome characterization of two wild-type measles viruses from Vietnamese infants during the 2014 outbreak

A large measles virus outbreak occurred across Vietnam in 2014. We identified and obtained complete measles virus genomes in stool samples collected from two diarrheal pediatric patients in Dong Thap Province. These are the first complete genome sequences of circulating measles viruses in Vietnam during the 2014 measles outbreak

Genome sequences of a novel Vietnamese bat bunyavirus

To document the viral zoonotic risks in Vietnam, fecal samples were systematically collected from a number of mammals in southern Vietnam and subjected to agnostic deep sequencing. We describe here novel Vietnamese bunyavirus sequences detected in bat feces. The complete L and S segments from 14 viruses were determined

Inhibition of Monkeypox virus replication by RNA interference

The Orthopoxvirus genus of Poxviridae family is comprised of several human pathogens, including cowpox (CPXV), Vaccinia (VACV), monkeypox (MPV) and Variola (VARV) viruses. Species of this virus genus cause human diseases with various severities and outcome ranging from mild conditions to death in fulminating cases. Currently, vaccination is the only protective measure against infection with these viruses and no licensed antiviral drug therapy is available. In this study, we investigated the potential of RNA interference pathway (RNAi) as a therapeutic approach for orthopox virus infections using MPV as a model. Based on genome-wide expression studies and bioinformatic analysis, we selected 12 viral genes and targeted them by small interference RNA (siRNA). Forty-eight siRNA constructs were developed and evaluated in vitro for their ability to inhibit viral replication. Two genes, each targeted with four different siRNA constructs in one pool, were limiting to viral replication. Seven siRNA constructs from these two pools, targeting either an essential gene for viral replication (A6R) or an important gene in viral entry (E8L), inhibited viral replication in cell culture by 65-95% with no apparent cytotoxicity. Further analysis with wild-type and recombinant MPV expressing green fluorescence protein demonstrated that one of these constructs, siA6-a, was the most potent and inhibited viral replication for up to 7 days at a concentration of 10 nM. These results emphasis the essential role of A6R gene in viral replication, and demonstrate the potential of RNAi as a therapeutic approach for developing oligonucleotide-based drug therapy for MPV and other orthopox viruses

Age-Related Comparisons of Evolution of the Inflammatory Response After Intracerebral Hemorrhage in Rats

In the hours to days after intracerebral hemorrhage (ICH), there is an inflammatory response within the brain characterized by the infiltration of peripheral neutrophils and macrophages and the activation of brain-resident microglia and astrocytes. Despite the strong correlation of aging and ICH incidence, and increasing information about cellular responses, little is known about the temporal- and age-related molecular responses of the brain after ICH. Here, we monitored a panel of 27 genes at 6 h and 1, 3, and 7 days after ICH was induced by injecting collagenase into the striatum of young adult and aged rats. Several molecules (CR3, TLR2, TLR4, IL-1β, TNFα, iNOS, IL-6) were selected to reflect the classical activation of innate immune cells (macrophages, microglia) and the potential to exacerbate inflammation and damage brain cells. Most of the others are associated with the resolution of innate inflammation, alternative pathways of macrophage/microglial activation, and the repair phase after acute injury (TGFβ, IL-1ra, IL-1r2, IL-4, IL-13, IL-4Rα, IL-13Rα1, IL-13Rα2, MRC1, ARG1, CD163, CCL22). In young animals, the up-regulation of 26 in 27 genes (not IL-4) was detected within the first week. Differences in timing or levels between young and aged animals were detected for 18 of 27 genes examined (TLR2, GFAP, IL-1β, IL-1ra, IL-1r2, iNOS, IL-6, TGFβ, MMP9, MMP12, IL-13, IL-4Rα, IL-13Rα1, IL-13Rα2, MRC1, ARG1, CD163, CCL22), with a generally less pronounced or delayed inflammatory response in the aged animals. Importantly, within this complex response to experimental ICH, the induction of pro-inflammatory, potentially harmful mediators often coincided with resolving and beneficial molecules