Identificazione di markers morfologici e sierologici di vulnerabilità della placca carotidea

Introduzione: L’indicazione alla rivascolarizzazione carotidea è comunemente posta in base alla percentuale di stenosi, alla presenza di sintomi neurologici ed alle condizioni cliniche del paziente. Una placca ad elevato potenziale embolico viene definita “vulnerabile”; la sua caratterizzazione, tuttavia, non è universalmente accettata ai fini della rivascolarizzazione. Lo scopo dello studio è indagare il ruolo del mezzo di contrasto ecografico (CEUS) nell’identificazione della placca carotidea vulnerabile. Materiali e Metodi: I pazienti sottoposti a endoarterectomia carotidea, sono stati valutati mediante TC cerebrale preoperatoria e CEUS. Le microbolle di contrasto rilevate nella placca, indicative di neovascolarizzazione, sono state quantificate in dB-E ed istologicamente valutate per cinque caratteristiche: (densità dei microvasi, spessore del cappuccio fibroso, estensione delle calcificazioni, infiltrato infiammatorio e core lipidico) il valore da 1 a 5, ottenuto in cieco, indica in grado di vulnerabilità della placca. L'ANOVA test, il test di Fisher e t Student sono stati usati per correlare le caratteristiche dei pazienti ed istologiche col valore di dB-E. Risultati: Di 22 pazienti (range 2-7.8, media 4.85 ±1.9 SD) vi era un numero più alto di sintomatici (7.40 ± 0.5) rispetto agli asintomatici (3.5 ± 1.4) (p = 0.002). Un più alto valore di dB-E si associava con la presenza di un sottile cappuccino fibroso (<200 µm, 5.96±1.5 vs. 3 ± 1,p = 0.01) ed un maggiore infiltrato infiammatorio (3.2 ± 0.9 vs. 6.4 ± 1.2, p = 0.03). Placche con vulnerabilità 5 si associavano ad un valore più alto di dB-E rispetto alle placche con vulnerabilità 1 (7.6 ± 0.2 vs. 2.5 ± 0.6, rispettivamente, p=0.001). Preoperatoriamente, le lesioni emboliche ipsilaterali alla TC, correlavano con un più alto valore di dB-E (5.96±1.5 vs. 3.0±1.0, p=0.01). Conclusioni: Il valore di dB-E alla CEUS indica l’estensione della neovascolarizzazione della placca carotidea e può essere utilizzato come marker di vulnerabilità della placca.

The Influence of Fractures on Vulnerability to Pollution of a Carbonate Aquifer: Monte Conero (Italy)

The carbonate outcrops of the anticline of Monte Conero (Italy) were studied in order to characterize the geometry of the fractures and to establish their influence on the petrophysical properties (hydraulic conductivity) and on the vulnerability to pollution. The outcrops form an analog for a fractured aquifer and belong to the Maiolica Fm. and the Scaglia Rossa Fm. The geometrical properties of fractures such as orientation, length, spacing and aperture were collected and statistically analyzed. Five types of mechanical fractures were observed: veins, joints, stylolites, breccias and faults. The types of fractures are arranged in different sets and geometric assemblages which form fracture networks. In addition, the fractures were analyzed at the microscale using thin sections. The fracture age-relationships resulted similar to those observed at the outcrop scale, indicating that at least three geological episodes have occurred in Monte Conero. A conceptual model for fault development was based on the observations of veins and stylolites. The fracture sets were modelled by the code FracSim3D to generate fracture network models. The permeability of a breccia zone was estimated at microscale by and point counting and binary image methods, whereas at the outcrop scale with Oda’s method. Microstructure analysis revealed that only faults and breccias are potential pathways for fluid flow since all veins observed are filled with calcite. According this, three scenarios were designed to asses the vulnerability to pollution of the analogue aquifer: the first scenario considers the Monte Conero without fractures, second scenario with all observed systematic fractures and the third scenario with open veins, joints and faults/breccias. The fractures influence the carbonate aquifer by increasing its porosity and hydraulic conductivity. The vulnerability to pollution depends also on the presence of karst zones, detric zones and the material of the vadose zone.

Vulnerability and robustness indices against blackouts in power grids

In this dissertation some novel indices for vulnerability and robustness assessment of power grids are presented. Such indices are mainly defined from the structure of transmission power grids, and with the aim of Blackout (BO) prevention and mitigation. Numerical experiments showing how they could be used alone or in coordination with pre-existing ones to reduce the effects of BOs are discussed. These indices are introduced inside 3 different sujects: The first subject is for taking a look into economical aspects of grids’ operation and their effects in BO propagation. Basically, simulations support that: the determination to operate the grid in the most profitable way could produce an increase in the size or frequency of BOs. Conversely, some uneconomical ways of supplying energy are shown to be less affected by BO phenomena. In the second subject new topological indices are devised to address the question of "which are the best buses to place distributed generation?". The combined use of two indices, is shown as a promising alternative for extracting grid’s significant features regarding robustness against BOs and distributed generation. For this purpose, a new index based on outage shift factors is used along with a previously defined electric centrality index. The third subject is on Static Robustness Analysis of electric networks, from a purely structural point of view. A pair of existing topological indices, (namely degree index and clustering coefficient), are combined to show how degradation of the network structure can be accelerated. Blackout simulations were carried out using the DC Power Flow Method and models of transmission networks from the USA and Europe.