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Control of geometry and kinematics on the state of stress of subduction zones: an application to the Mediterranean region.
No full textKnowing the stress field at subduction zones is fundamental as here is released most of the seismic energy in the Earth. In particular, most MW > 8.0 earthquakes originate at shallow depths along the frictional interface between subducting and overriding plates. This observation emphasizes the crucial role played by the geologic-time scale dynamics of convergent margins over the short-time scale seismogenic processes. Despite an obvious relevance to seismic hazard, knowing the driving forces generating the stress field at subduction zones is a long-standing problem. In this thesis, by means of 2D and 3D numerical viscoelastic models, I simulated the stress field in convergent plate margins to evaluate which properties control subduction dynamics. Models are built to evaluate the contribution of plate kinematics, geometry of the system, rheology and gravitational forces to the definition of the present-day stress field at different subduction zones. This has been achieved with the development of several sets of generic (i.e., not simulating specific subduction zones) 2D and 3D models. The aim is to analyze the interaction between the subducted slabs and the geodynamic forces (e.g., slab pull, mantle flow, plate convergence) that stress the system, to reproduce the observed stress fields measured in different subduction zones worldwide for both the upper and lower plates at crustal depths and for intermediate and deep subducted lithosphere. The interaction between subducting slabs and the viscosity jump at upper-lower mantle transition has been also investigated. Although generic, model geometries are consistent with natural geometries observed in real subduction zones worldwide. Modelling results are compared with stress data available in the world stress map database for different convergent margins. To define the stress field affecting the subducting plates, special attention must be paid to the choice of the righteous initial parameters, since from them depend the delicate balance between the applied tectonic forces and the geometric characteristics of the whole system. For this reason and to validate or reject the observations made for the general cases, the central Mediterranean subduction system was chosen to model a natural subduction zone. Building and constraining a model requires the knowledge of the real system. Subduction zones are primarily described by their geometry, and today the slab interfaces in the Mediterranean are still uncertain. I defined them reviewing and integrating literature data from various disciplines, collecting geometries into a specifically designed database. Unlike similar databases already available in the literature, in the database that I contributed to build the subduction interfaces are fully-parametrized, i.e., characterized by geometric (strike, dip, depth), kinematics and dynamic (rake, slip rate, seismic coupling, maximum earthquake magnitude) parameters. The database so designed, and its on-line publication makes it a valuable tool for the geometric description of active subductions in the Mediterranean area and provide the basis to investigate their seismic hazard
Valutazione della vasoreattività cerebrale mediante doppler transcranico in pazienti affetti da malattia di Parkinson e mild cognitive impairment
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NONCOVALENT BIFUNCTIONAL ORGANOCATALYSIS APPLIED TO THE ACHIEVEMENT OF CHIRAL EPOXIDES AND 1,2-DIOLS
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RUOLO DI NOTCH3 NELLA MODULAZIONE DELL’ESPRESSIONE DI CXCR4 NEI TIMOCITI IMMATURI
No full text• RIASSUNTO
I recettori Notch (N1, N2 e N3) regolano la scelta differenziativa T (Artavanis-Tsakonas et al., 1999). L'attivazione costitutiva del signaling di Notch è una delle maggiori cause dell’insorgenza della leucemia linfoblastica acuta (T-ALL) nel topo e negli esseri umani.
La funzione di Notch3 come oncogene nella T-ALL è stata dimostrata da un modello murino creato nel nostro laboratorio, caratterizzato dall’espressione costitutiva della forma attiva di Notch3 (N3-IC) nei timociti immaturi (N3-IC Tg) (Bellavia et al., 2000). Nei topi N3-IC Tg è stata osservata una deregolazione della proliferazione e della maturazione nella fase di transizione da preT a T, oltre all'attivazione costitutiva del preTCR (Bellavia et al., 2002).
Il differenziamento delle cellule T dipende da molti segnali forniti dallo stroma, il quale produce citochine, chemochine e ligandi e sostiene i processi maturativi timocitari all'interno del micro-ambiente timico (Sun et al., 2010). In particolare è noto che il recettore di chemochine CXCR4 è espresso sulla superficie dei timociti dallo stadio DN1 (doppi negativi 1) a quello DP (doppi positivi), con un picco di espressione nelle transizioni DN2-DN3 e DN-DP, mentre è completamente assente nei SP (singolo positivi) (Plotkin et al., 2003). Ѐ altresì dimostrato che il signaling cooperativo fra il preTCR, CXCR4 e Notch3 è richiesto nella selezione β per consentire il differenziamento dei timociti T dallo stadio DN a quello DP (Janas et al., 2010). Infatti il fattore derivato dalle cellule stromali SDF-1 (CXCL12) ed il suo recettore CXCR4 promuovono la sopravvivenza dei timociti DN e regolano la migrazione durante la transizione da DN a DP (Plotkin et al., 2003). Inoltre è stato suggerito un ruolo dell'asse CXCR4/SDF-1 nello sviluppo e nella progressione della T-ALL (Scupoli et al., 2008).
Scopo della Tesi di Dottorato è stato lo studio del cross-talk molecolare della via di segnalazione, innescata dall’over-espressione di Notch3 sulla pathway della chemochina CXCR4, come possibile meccanismo deregolatore dei programmi differenziativi intratimici in un modello murino di T-ALL.
Esperimenti al FACS hanno dimostrato una diminuzione nella percentuale di cellule DN CXCR4 positive nel topo N3-IC Tg rispetto al wt, non attribuibile ad alcuna riduzione nel numero totale di timociti DN. Al contrario è stato osservato un incremento dell’espressione di CXCR4 nelle cellule DP. Esperimenti di migrazione ex vivo dei timociti, in risposta al ligando fisiologico, CXCL12, dimostrano una alterata migrazione dei timociti dei topi N3-IC Tg rispetto al wt. Inoltre sono stati eseguiti esperimenti di cell sorting focalizzati all’analisi molecolare della sottopopolazione timocitaria delle DN. I dati sembrano suggerire che l’over-espressione di Notch3 possa compromettere eventi iniziali nella maturazione delle cellule pre-T, riducendo anche l’espressione di EpCAM, una molecola di adesione omotipica coinvolta nell’interazione linfo/stromale del timo. Supponiamo che questi eventi possano essere coinvolti nello sviluppo della T-ALL
Un metodo innovativo per la selezione di una frazione ideale per la datazione delle malte tramite 14C: il protocollo Cryo2SoniC
No full textTo date, mortar radiocarbon (14C) dating represents one of the main “open issues” involving the whole radiocarbon community because, after about 50 years of experimentation, the possibility to evaluate absolute chronologies for these artifact by radiocarbon remains still uncertain. This work describes i) the development of a new methodology, called Cryo2SoniC, aimed to select a fraction of mortars recording the time of setting, ii) the evaluation of Cryo2SoniC main drawbacks and successes, when it is applied on archaeological mortar. The proposed method is based upon a physical procedure (ultrasonication) isolating only the binder calcite formed by means of the absorption of atmospheric CO2 during the mortar setting.
Proposed procedure was tested, at first, on a series of synthetic mortars produced in the laboratory and lime lumps, using a first version of the separation method (i.e. CryoSoniC) and then applying the ungraded version, Cryo2SoniC, on a series of archeological samples from different important historic monuments and excavations. All measured radiocarbon ages were compared with their chronological reference allowing accuracy evaluation. Radiocarbon dating was performed on the selected fractions using high-precision (i.e. 0.3% prescision) Accelerator Mass Spectroscometry (AMS). Mineralogical investigations for mortar charcterization were performed on original mortars by X-Ray Diffraction (XRD) of powders, observations of thin section with Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). An inter-comparison exercise has been performed between CIRCE and the Poznan Radiocarbon Laboratory to verify the efficiency of different separation methods (Cryo2SoniC vs stepped digestion) performed on the same samples.
InfraRed Fourier Transformed Spectroscopy (FTIR), SEM and ChatodoLuminescence (CL) analyses were performed to verify eventual dead carbon contamination affecting Cyo2SoniC produced fractions and consequentially develop a diagnostic tool i) to gather information about observed pitfalls of the methodology ii) to preliminarly predict the quality of CryoSoniC isolated fractions.
Final balance of this research is the reliability and efficiency of the Cryo2SoniC method on a widespread spectra of mortar typologies, highlighting its weak points and suggesting alternative solutions such as the purification of lime lumps incased in mortars
Identificazione di nuovi marcatori molecolari nelle LAL mediante l'integrazione del profilo di espressione genica e dello stato mutazionale dei nuovi geni
No full textControl strategies for the vehicle routing problem applied to medical emergencies
No full textThis thesis deals with dynamic Multi-Vehicle
Routing Problem (MVRP) in both deterministic and stochastic scenarios. The objective of the MVRP is to find the best paths
for a fleet of vehicles, with the aim of visiting a set of targets.
Based on the Cooperative Receding Horizon (CRH) approach
proposed by Cassandras et al.(CRH) for the Euclidean case, this thesis: i) presents another algorithm that is more efficient with clustered targets (tCRH); ii) illustrates an algorithm that exploits CRH and tCRH strengths (aCRH); iii) extends CRH, tCRH and aCRH to realistic urban map case