La presenza dei cristiani in Sicilia in et\ue0 islamica: considerazioni preliminari relative a Palermo e ad Agrigento

La presenza delle comunit\ue0 cristiane nella Sicilia islamica, nota dalla fonti scritte, \ue8 stata da sempre sottovalutata dalla ricerca archeologica. In questo articolo si \ue8 cercato di mettere in evidenza le labili tracce di queste comunit\ue0 in due grandi citt\ue0 della Sicilia islamica: Palermo ed Agrigento

Critical point for the CAF-F phase transition at charge neutrality in bilayer graphene

We report on magneto-transport measurements up to 30 T performed on a bilayer graphene Hall bar, enclosed by two thin hexagonal boron nitride flakes. Our high mobility sample exhibits an insulating state at neutrality point which evolves into a metallic phase when a strong in-plane field is applied, as expected for a transition from a canted antiferromagnetic to a ferromagnetic spin ordered phase. For the first time we individuate a temperature-independent crossing in the four-terminal resistance as a function of the total magnetic field, corresponding to the critical point of the transition. We show that the critical field scales linearly with the perpendicular component of the field, as expected from the underlying competition between the Zeeman energy and interaction-induced anisotropies. A clear scaling of the resistance is also found and an universal behavior is proposed in the vicinity of the transition

Lo scavo della Chiesa di Santa Maria Degli Angeli alla Gancia: indicatori archeologici della prima età islamica a Palermo

Lo scavo in occasione del restauro della chiesa di Santa Maria degli Angeli alla Gancia a Palermo ha permesso di recuperare alcune stratigrafie affidabili relative alla prima età islamica a Palermo. Lo studio della ceramica ha restituito una serie di indicatori cronologici per il IX-X secolo nonché di proporre nuove cronologie per alcune classi di materiali. Relativamente alla storia della città questo scavo ha aggiunto alcune note importanti che riguardano il porto e la cittadella e mirale la al-Halisah

Dati sulla circolazione della ceramica e sulle rotte del medioevo occidentale attraverso i contesti tardoantichi e medievali di Marettimo

In this paper will be described the ceramic found in the site Contrada Case Romane in the island of Marettimo. On this site a monastic community was founded in the end of the 5th century. This settlement was destroyed in the 8th century and a new one founded in the same location under Norman rule (end of 11th century). The items discovered prove that between the 5th and the 7th century the island was part of a Mediterranean route linking Africa with Rome and the main locations of the western Mediterranean sea. The findings of amphorae produced in the central-southern Tyrrhenian sea between the end of the 7th century and the beginning of the 8th century reveal the close relationship of this monastic settlement with the great ecclesiastic praesidia of the Campi Flegrei. Ceramic belonging to the Norman period and to the 13th century does not differ from the one found in other Sicilian sites; this fact confirms the dependency from mainland of the tiny community living in the island

Low cost system for visualization and exhibition of pottery finds in archeological museums

The objective of this project is to build a low-cost system for surveying, modeling, prototyping and interactive visualizing aimed at the enhancement of islamic pottery finds of X – XI centuries. The system will allow various applications: the creation of systems for displaying artifacts from the museum alongside the exhibition, the virtual view of restorations from fragments, including AR and VR, the physical reconstruction of the original form using 3D printer to show the pieces in their entirety, as well as the construction of interactive virtual archives to be made available to scholars and visitors

Coexistence of bulk and surface states probed by Shubnikov-de Haas oscillations in Bi2_2Se3_3 with high charge-carrier density

Topological insulators are ideally represented as having an insulating bulk with topologically protected, spin-textured surface states. However, it is increasingly becoming clear that these surface transport channels can be accompanied by a finite conducting bulk, as well as additional topologically trivial surface states. To investigate these parallel conduction transport channels, we studied Shubnikov-de Haas oscillations in Bi$_2$Se$_3$ thin films, in high magnetic fields up to 30 T so as to access channels with a lower mobility. We identify a clear Zeeman-split bulk contribution to the oscillations from a comparison between the charge-carrier densities extracted from the magnetoresistance and the oscillations. Furthermore, our analyses indicate the presence of a two-dimensional state and signatures of additional states the origin of which cannot be conclusively determined. Our findings underpin the necessity of theoretical studies on the origin of and the interplay between these parallel conduction channels for a careful analysis of the material's performance.Comment: Manuscript including supplemental materia

Anisotropic and strong negative magneto-resistance in the three-dimensional topological insulator Bi2Se3

We report on high-field angle-dependent magneto-transport measurements on epitaxial thin films of Bi2Se3, a three-dimensional topological insulator. At low temperature, we observe quantum oscillations that demonstrate the simultaneous presence of bulk and surface carriers. The magneto- resistance of Bi2Se3 is found to be highly anisotropic. In the presence of a parallel electric and magnetic field, we observe a strong negative longitudinal magneto-resistance that has been consid- ered as a smoking-gun for the presence of chiral fermions in a certain class of semi-metals due to the so-called axial anomaly. Its observation in a three-dimensional topological insulator implies that the axial anomaly may be in fact a far more generic phenomenon than originally thought.Comment: 6 pages, 4 figure

disorder and de coherence in graphene probed by low temperature magneto transport weak localization and weak antilocalization

We studied weak localization (WL) and and weak antilocalization (WAL) in a eight-contacts Hall bar made of exfoliated monolayer graphene on Si-SiO2, by means of magneto-transport experiments, at temperatures between 0.3 K and 15 K. At low carrier density (n ≊ 7 × 1011 cm−2) we observed a transition from WL to WAL driven by the increasing of the magnetic field, while at high carrier density (n ≊ 2 × 1012 cm−2) only WL was observable. We analyzed the magnetic field driven WL-WAL transition and we evaluated the temperature dependence of the de-coherence parameters using an alternative method compared to previous studies. The values we obtained were corroborated by a root-mean-square analysis of the amplitude of highly-reproducible universal conductance fluctuations