Reliability assessment of open-source multiscale landslide susceptibility maps and effects of their fusion

Several landslide susceptibility (LS) maps at various scales of analysis have been performed with specific zoning purposes and techniques. Supervised machine learning algorithms (ML) have become one of the most diffused techniques for landslide prediction, whose reliability is firmly based on the quality of input data. Site-specific landslide inventories are often more accurate and complete than national or worldwide databases. For these reasons, detailed landslide inventory and predisposing variables must be collected to derive reliable LS products. However, high-quality data are often rare, and risk managers must consider lower-resolution available products with no more than informative purposes. In this work, we compared different ML models to select the most accurate for large-scale LS assessment within the Municipality of Rome. The ExtraTreesClassifier outperformed the others reaching an average F1-score of 0.896. Thereafter, we addressed the reliability of open-source LS maps at different scales of analysis (global to regional) by means of statistical and spatial analysis. The obtained results shed light on the difference in hazard zoning depending on the scale and mapping unit. An approach for low-resolution LS data fusion was attempted, assessing the importance of the adopted criteria, which increased the ability to detect occurred landslides while maintaining precision

Contribution of high-resolution virtual outcrop models for the definition of rockfall activity and associated hazard modelling

This is the final version. Available from MDPI via the DOI in this record. Data Availability Statement: The data are contained within the article.The increased accessibility of drone technology and structure from motion 3D scene reconstruction have transformed the approach for mapping inaccessible slopes undergoing active rockfalls and generating virtual outcrop models (VOM). The Poggio Baldi landslide (Central Italy) and its natural laboratory offers the possibility to monitor and characterise the slope to define a workflow for rockfall hazard analysis. In this study, the analysis of multitemporal VOM (2016–2019) informed a rockfall trajectory analysis that was carried out with a physical-characteristic-based GIS model. The rockfall scenarios were reconstructed and then tested based on the remote sensing observations of the rock mass characteristics of both the main scarp and the rockfall fragment inventory deposited on the slope. The highest concentration of trajectory endpoints occurred at the very top of the debris talus, which was constrained by a narrow channel, while longer horizontal travel distances were allowed on the lower portion of the slope. To further improve the understanding of the Poggio Baldi landslide, a time-independent rockfall hazard analysis aiming to define the potential runout associated with several rock block volumetric classes is a critical component to any subsequent risk analysis in similar mountainous settings featuring marly–arenaceous multilayer sedimentary successions and reactivated main landslide scarps.Sapienza University of RomeNHAZCA SrlParco Nazionale delle Foreste Casentinesi, Monte Falterona e CampignaDepartment of Earth Sciences of the University of Rome “Sapienza

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

Type-3 metabotropic glutamate receptors negatively modulate bone morphogenetic protein receptor signaling and support the tumourigenic potential of glioma-initiating cells

Targeted-therapies enhancing differentiation of glioma-initiating cells (GICs) are potential innovative approaches to the treatment of malignant gliomas. These cells support tumour growth and recurrence and are resistant to radiotherapy and chemotherapy. We have found that GICs express mGlu3 metabotropic glutamate receptors. Activation of these receptors sustained the undifferentiated state of GICs in culture by negatively modulating the action of bone morphogenetic proteins, which physiologically signal through the phosphorylation of the transcription factors, Smads. The cross-talk between mGlu3 receptors and BMP receptors was mediated by the activation of the mitogen-activated protein kinase pathway. Remarkably, pharmacological blockade of mGlu3 receptors stimulated the differentiation of cultured GICs into astrocytes, an effect that appeared to be long lasting, independent of the growth conditions, and irreversible. In in vivo experiments, a 3-month treatment with the brain-permeant mGlu receptor antagonist, LY341495 limited the growth of infiltrating brain tumours originating from GICs implanted into the brain parenchyma of nude mice. While clusters of tumour cells were consistently found in the brain of control mice, they were virtually absent in a large proportion of mice treated with LY341495. These findings pave the way to a new non-cytotoxic treatment of malignant gliomas based on the use of mGlu3 receptor antagonists. \uc2\ua9 2008 Elsevier Ltd. All rights reserved

Type-3 metabotropic glutamate receptors regulate chemoresistance in glioma stem cells, and their levels are inversely related to survival in patients with malignant gliomas

Drug treatment of malignant gliomas is limited by the intrinsic resistance of glioma stem cells (GSCs) to chemotherapy. GSCs isolated from human glioblastoma multiforme (GBM) expressed metabotropic glutamate receptors (mGlu3 receptors). The DNA- alkylating agent, temozolomide, killed GSCs only if mGlu3 receptors were knocked down or pharmacologically inhibited. In contrast, mGlu3 receptor blockade did not affect the action of paclitaxel, etoposide, cis-platinum, and irinotecan. mGlu3 receptor blockade enabled temozolomide toxicity by inhibiting a phosphatidylinositol-3-kinase/nuclear factor-jB pathway that supports the expression of O6-methylguanine-DNA methyltransferase (MGMT), an enzyme that confers resistance against DNA- alkylating agents. In mice implanted with GSCs into the brain, temozolomide combined with mGlu3 receptor blockade substantially reduced tumor growth. Finally, 87 patients with GBM undergoing surgery followed by adjuvant chemotherapy with temozolomide survived for longer time if tumor cells expressed low levels of mGlu3 receptors. In addition, the methylation state of the MGMT gene promoter in tumor extracts influenced survival only in those patients with low expression of mGlu3 receptors in the tumor. These data encourage the use of mGlu3 receptor antagonists as add-on drugs in the treatment of GBM, and suggest that the transcript of mGlu3 receptors should be measured in tumor specimens for a correct prediction of patients\u2019 survival in response to temozolomide treatment