A fresh look at Ħaġar Qim and Mnajdra temples

Our megalithic temples relate many stories. The stories that intrigue us most are those that tell us about their beginnings, their construction, use and development in prehistory. However, they do provide evidence for a different story, that which starts with their discovery by modem society. During this part of their lifespan these monuments are not only studied and analysed by scholars trying to identify their origins, but are also restored and reconstructed, thus undergoing physical changes which are not always immediately evident. Numerous restoration and conservation interventions have taken place at both Magar Qim and Mnajdra. Records of only a few of these interventions have been kept, and in some cases even this documentation is missing from our archives. It is in fact the actual visual examination of the remains, as well as the examination of photographic and pictorial evidence, that allows for their identification. This factor often makes it difficult to attribute a date to these interventions and to identify the methods and materials that were used.peer-reviewe

A 16th century Iron Breech-Loading Swivel-Gun

Early in May 2000, the Mediterranean gave up another of its jealously kept treasures. While pleasure diving off Malta's southern coast, Michael Spiteri, a technical staff member of the Museums Department Archaeology Section discovered a rare and unusual gun. Lying there on the seabed was a sixteenth century, breechloading swivel-gun. Seafarers of various nations used small swivel-guns of this type extensively on ships, for many centuries. However, not that many have survived and at the time it was found, this was the first officially recorded discovery in Maltese waters of an early, breech-loading gun. Certainly not as sensational as the Riace Bronzes, this fascinating relic is nonetheless of considerable importance even by international standards.peer-reviewe

The Intermodulation Coefficient of an Inhomogeneous Superconductor

The high-T_c cuprate superconductors are now believed to be intrinsically inhomogeneous. We develop a theory to describe how this inhomogeneity affects the intermodulation coefficient of such a material. We show that the continuum equations describing intermodulation in a superconducting layer with spatially varying properties are formally equivalent to those describing an inhomogeneous dielectric with a nonzero cubic nonlinearity. Using this formal analogy, we calculate the effect of inhomogeneity on the intermodulation coefficient in a high-T_c material, using several assumptions about the topology of the layer, and some simple analytical approximations to treat the nonlinearity. For some topologies, we find that the intermodulation critical supercurrent density J_{IMD} is actually enhanced compared to a homogeneous medium, thereby possibly leading to more desirable material properties. We discuss this result in light of recent spatial mappings of the superconducting energy gap in BSCCO-2212.Comment: 26 pages, 9 figures, accepted for publication in the Journal of Applied Physic