INTEGRAZIONE TRA MONITORAGGIO E MODELLAZIONE DELLE GRANDI FRANE IN ROCCIA NELL'OTTICA DELL'ALLERTAMENTO RAPIDO

Nella presente nota si intendono illustrare gli sviluppi di un progetto di ricerca che prevede l'integrazione tra tecniche di monitoraggio e modelli numerici avanzati per lo studio delle grandi frane in roccia ai fini di un allertamento rapido delle popolazioni e delle infrastrutture esposte al rischio. In particolare tra le tecniche di monitoraggio si prenderanno in esame l'interferometria radar da terra (GBInSAR), mentre a livello di modellazione numerica l'attenzione verrà rivolta al metodo ibrido elementi finiti/elementi distinti (FDEM). Con riferimento ad alcuni casi reali, i modelli numerici, validati e calibrati sui dati di monitoraggio, verranno utilizzati per la produzione di scenari di evoluzione dei fenomeni franosi oggetto di studio. I risultati della modellazione consentiranno di definire particolari soglie (spostamenti, velocità, altezze piezometriche etc..), in base ai diversi scenari simulati, da cui si potrà ottenere una valutazione rapida del livello di criticità associata al fenomeno in esam

INTEGRAZIONE TRA MONITORAGGIO E MODELLAZIONE DELLE GRANDI FRANE IN ROCCIA NELL’OTTICA DELL’ALLERTAMENTO RAPIDO

Nella presente nota si intendono illustrare gli sviluppi di un progetto di ricerca che prevede l’integrazione tra tecniche di monitoraggio e modelli numerici avanzati per lo studio delle grandi frane in roccia ai fini di un allertamento rapido delle popolazioni e delle infrastrutture esposte al rischio. In particolare tra le tecniche di monitoraggio si prenderanno in esame l’interferometria radar da terra (GBInSAR), mentre a livello di modellazione numerica l’attenzione verrà rivolta al metodo ibrido elementi finiti/elementi distinti (FDEM). Con riferimento ad alcuni casi reali, i modelli numerici, validati e calibrati sui dati di monitoraggio, verranno utilizzati per la produzione di scenari di evoluzione dei fenomeni franosi oggetto di studio. I risultati della modellazione consentiranno di definire particolari soglie (spostamenti, velocità, altezze piezometriche etc..), in base ai diversi scenari simulati, da cui si potrà ottenere una valutazione rapida del livello di criticità associata al fenomeno in esame

Study of electrically active defects in epitaxial layers on silicon

Electrically active defects in silicon-based epitaxial layers on silicon substrates have been studied by Deep-Level Transient Spectroscopy (DLTS). Several aspects have been investigated, like, the impact of the pre-epi cleaning conditions and the effect of a post-deposition anneal on the deep-level properties. It is shown that the pre-cleaning thermal budget has a strong influence on the defects at the substrate/epi layer interface. At the same time, a post-deposition Forming Gas Anneal can passivate to a large extent the active defect states. Finally, it is shown that application of a post-deposition anneal increases the out-diffusion of carbon from a Si:C stressor layer into the p-type CZ substrate

Seismic response of a single and a set of filled joints of viscoelastic deformational behaviour

Rock joints are often filled with weak medium, for example, saturated clay or sand, of viscoelastic nature. Their effects on wave propagation can be modelled as displacement and stress discontinuity conditions. The viscoelastic behaviour of the filled joint can be described by either the Kelvin or the Maxwell models. The analytical solutions for wave propagation across a single joint are derived in this paper by accounting for the incident angle, the non-dimensional joint stiffness, the non-dimensional joint viscosity and the acoustic impedance ratio of the filled joint. It is shown that the viscoelastic behaviour results in dissipation of wave energy and frequency dependence of the reflection and transmission coefficients. Based on curve fitting of the experimental data of P-wave propagation across a single joint filled with saturated sand, both the Kelvin and Maxwell models are found to reproduce the behaviour of the filled joint, in terms of the amplitude and frequency contents. Then, wave transmission across a filled joint set is studied with the virtual wave source method and the scattering matrix method, where multiple wave reflections among joints are taken into account. It is shown that the non-dimensional joint spacing and the number of joints have significant effects on the transmission coefficient

Discontinuous Transition from a Real Bound State to Virtual Bound State in a Mixed-Valence State of SmS

Golden SmS is a paramagnetic, mixed-valence system with a pseudogap. With increasing pressure across a critical pressure Pc, the system undergoes a discontinuous transition into a metallic, anti-ferromagnetically ordered state. By using a combination of thermodynamic, transport, and magnetic measurements, we show that the pseudogap results from the formation of a local bound state with spin singlet. We further argue that the transition Pc is regarded as a transition from an insulating electron-hole gas to a Kondo metal, i.e., from a spatially bound state to a Kondo virtually bound state between 4f and conduction electrons.Comment: 5 pages, 5 figure

Systematics of electronic and magnetic properties in the transition metal doped Sb2_2Te3_3 quantum anomalous Hall platform

The quantum anomalous Hall effect (QAHE) has recently been reported to emerge in magnetically-doped topological insulators. Although its general phenomenology is well established, the microscopic origin is far from being properly understood and controlled. Here we report on a detailed and systematic investigation of transition-metal (TM)-doped Sb$_2$Te$_3$. By combining density functional theory (DFT) calculations with complementary experimental techniques, i.e., scanning tunneling microscopy (STM), resonant photoemission (resPES), and x-ray magnetic circular dichroism (XMCD), we provide a complete spectroscopic characterization of both electronic and magnetic properties. Our results reveal that the TM dopants not only affect the magnetic state of the host material, but also significantly alter the electronic structure by generating impurity-derived energy bands. Our findings demonstrate the existence of a delicate interplay between electronic and magnetic properties in TM-doped TIs. In particular, we find that the fate of the topological surface states critically depends on the specific character of the TM impurity: while V- and Fe-doped Sb$_2$Te$_3$ display resonant impurity states in the vicinity of the Dirac point, Cr and Mn impurities leave the energy gap unaffected. The single-ion magnetic anisotropy energy and easy axis, which control the magnetic gap opening and its stability, are also found to be strongly TM impurity-dependent and can vary from in-plane to out-of-plane depending on the impurity and its distance from the surface. Overall, our results provide general guidelines for the realization of a robust QAHE in TM-doped Sb$_2$Te$_3$ in the ferromagnetic state.Comment: 40 pages, 13 figure

Evaluating the effects of land use and strategies for parking and transit supply on mode choice of downtown commuters

JTLU vol 5, no 2, pp 103-119 (2012)Metropolitan regions around the world are looking for sustainable strategies to reduce motor-vehicle traffic congestion, energy consumption, and emissions. These strategies include land-use policies as well as improvements to public transit services. This empirical work aims at studying the potential impact of land use (LU), public transit supply (PT), and parking pricing strategies on the mode choice of commuters living in the commuter rail line catchments in the Montreal (Canada) region. It makes use of an econometric modeling approach with both transportation mode choice and neighborhood type choice as simultaneous decisions, in order to take into account the endogeneity of these choices. The neighborhood choices are represented by neighborhood typologies derived from a cluster analysis using land use and transit supply indicators (population density, land use mix, and bus transit supply). As part of the outcomes of this study, the elasticities of mode choice with respect to commuter-transit fees, travel time reductions, and hourly parking costs are estimated. From the results, it is observed that a reduction of 10 percent in the transit fee or relative travel time would increase mode split by 10 percent and 3 percent respectively. The effect of age on both mode choice and neighborhood choice is also estimated. e individual and household structure factors associated with mode choice and/or residential neighborhood choice are also identified. Commuter age affects both outcomes. Income and gender affect mode choice while car ownership and the presence of children are linked to neighborhood choice

Different features of tumor-associated NK cells in patients with low-grade or high-grade peritoneal carcinomatosis

Peritoneal carcinomatosis (PC) is a rare disease defined as diffused implantation of neoplastic cells in the peritoneal cavity. This clinical picture occurs during the evolution of peritoneal tumors, and it is the main cause of morbidity and mortality of patients affected by these pathologies, though cytoreductive surgery with heated intra-peritoneal chemotherapy (CRS/HIPEC) is yielding promising results. In the present study, we evaluated whether the tumor microenvironment of low-grade and high-grade PC could affect the phenotypic and functional features and thus the anti-tumor potential of NK cells. We show that while in the peritoneal fluid (PF) of low-grade PC most CD56dim NK cells show a relatively immature phenotype (NKG2A+KIR\u2013CD57\u2013CD16dim), in the PF of high-grade PC NK cells are, in large majority, mature (CD56dimKIR+CD57+CD16bright). Furthermore, in low-grade PC, PF-NK cells are characterized by a sharp down-regulation of some activating receptors, primarily NKp30 and DNAM-1, while, in high-grade PC, PF-NK cells display a higher expression of the PD-1 inhibitory checkpoint. The compromised phenotype observed in low-grade PC patients corresponds to a functional impairment. On the other hand, in the high-grade PC patients PF-NK cells show much more important defects that only partially reflect the compromised phenotype detected. These data suggest that the PC microenvironment may contribute to tumor escape from immune surveillance by inducing different NK cell impaired features leading to altered anti-tumor activity. Notably, after CRS/HIPEC treatment, the altered NK cell phenotype of a patient with a low-grade disease and favorable prognosis was reverted to a normal one. Our present data offer a clue for the development of new immunotherapeutic strategies capable of restoring the NK-mediated anti-tumor responses in association with the CRS/HIPEC treatment to increase the effectiveness of the current therapy

Kondo engineering : from single Kondo impurity to the Kondo lattice

In the first step, experiments on a single cerium or ytterbium Kondo impurity reveal the importance of the Kondo temperature by comparison to other type of couplings like the hyperfine interaction, the crystal field and the intersite coupling. The extension to a lattice is discussed. Emphasis is given on the fact that the occupation number $n_f$ of the trivalent configuration may be the implicit key variable even for the Kondo lattice. Three $(P, H, T)$ phase diagrams are discussed: CeRu$_2$Si$_2$, CeRhIn$_5$ and SmS