From commodity to money: The rise of silver coinage around the Ancient Mediterranean (sixth-first centuries bce).

The reasons why the Western Mediterranean, especially Carthage and Rome, resisted monetization relative to the Eastern Mediterranean are still unclear. We address this question by combining lead (Pb) and silver (Ag) isotope abundances in silver coinage from the Aegean, Magna Graecia, Carthage and Roman Republic. The clear relationships observed between 109Ag/107Ag and 208Pb/206Pb reflect the mixing of silver ores or silver objects with Pb metal used for cupellation. The combined analysis of Ag and Pb isotopes reveals important information about the technology of smelting. The Greek world extracted Ag and Pb from associated ores, whereas, on the Iberian Peninsula, Carthaginians and Republican-era Romans applied Phoenician cupellation techniques and added exotic Pb to Pb-poor Ag ores. Massive Ag recupellation is observed in Rome during the Second Punic War. After defeating the Carthaginians and the Macedonians in the late second century bce, the Romans brought together the efficient, millennium-old techniques of silver extraction of the Phoenicians, who considered this metal a simple commodity, with the monetization of the economy introduced by the Greeks.

First Isolation of Pseudogymnoascus destructans, the Fungal Causative Agent of White-Nose Disease, in Bats from Italy.

White-nose disease, caused by the dermatophyte Pseudogymnoascus destructans, is a devastating pathology that has caused a massive decline in the US bat populations. In Europe, this fungus and the related infection in bats have been recorded in several countries and for many bat species, although no mass mortality has been detected. This study reports for the first time the presence of P. destructans in Italy. The fungus was isolated in the Rio Martino cave, a site located in the Western Alps and included in the Natura 2000 network. Twenty bats, belonging to five different species, were analysed. The fungus was retrieved on eight individuals of Myotis emarginatus. The allied keratolytic species P. pannorum was observed on two other individuals, also belonging to M. emarginatus. Strains were isolated in pure culture and characterized morphologically. Results were validated through molecular analyses. Future work should be dedicated to understand the distribution and the effects of the two Pseudogymnoascus species on Italian bats.

Photo-chemical study and optical properties of microtips self- written on vertical laser diodes using NIR photo-polymerization.

Near infra-red (NIR) self-guided photo-polymerization is investigated in the context of micro-optics photo-fabrication on VCSELs (Vertical-Cavity Surface Emitting Lasers). We present the optimized process we have developed to allow for a collective fabrication on III-V devices wafers under real-time optical monitoring. The influence of photo-chemical parameters on final micro-elements dimensions is studied for two types of single mode 760 nm VCSELs. The difference of the resulting tip shape between the two lasers is due to the strong differences of their emissions, as they are nicely reproduced by the computed near-field profiles. The tip shapes are also compared to those produced by the light emitted by an optical fiber and differences with VCSEL tips are discussed. Also the VCSEL characteristics with fabricated tips are discussed and found in good agreement with optical modeling.

Surface micromachined tunable 1.55 µm-VCSEL with 102 nm continuous single-mode tuning.

For the first time a vertical-cavity surface-emitting laser (VCSEL) with a single-mode wavelength-tuning over 102 nm in the range of 1550 nm is demonstrated. The fiber-coupled optical output power has a maximum of 3.5 mW and is > 2 mW over the entire tuning range. The sidemode suppression ratios are > 45 dB. The wavelength tuning is achieved with the micro-electro mechanical actuation of a mirror membrane fabricated with surface micro-machining for on-wafer mass production. The mirror membrane consists of low cost dielectric materials (SiOx/SiNy) deposited with low temperature (< 100°C) Plasma Enhanced Chemical Vapor Deposition (PECVD).

Locking characteristics of Fabry-Perot semiconductor laser oscillators with side-mode injection.

A model to evaluate frequency locking by means of a power injection near a side mode of the free-running frequency is presented. Semiconductor optical nonlinearities govern the locking problem; they are represented by nonlinear coefficients that take into account both carrier fluctuations and all relevant fast phenomena. Field equations are derived from coupled-mode theory, accounting for longitudinal variations by means of appropriate mean values. Examples of results show both the single locked frequency-stable operation region and the case when the injected signal and the free-running field coexist.

Highly nondegenerate four-wave mixing in semiconductor laser oscillators.

A complete model to evaluate frequency conversion that is due to highly nondegenerate four-wave mixing in Fabry-Perot laser oscillators is presented; propagation effects are taken into account. Simplified expressions are obtained in the limit of perfectly reflecting mirrors that permit analytical solutions; they are in good agreement with the results of the numerical analysis. Examples of results exhibit interesting features such as a correction factor for the relaxation frequency peak, good conversion gain up to the terahertz region, and complex behavior of the frequency response near side-mode resonances.