Excavations at Tas-Silg, Malta : a preliminary report on the 1996-1998 campaigns conducted by the Department of Classics and Archaeology of the University of Malta

The area known as Tas-Silg is situated in the south-eastern part of the island of Malta, close to Marsaxlokk harbour. In reality the place name refers to the small church dedicated to Our Lady of the Snows (hence Tas-Silg) situated at the point where the narrow · road from Zejtun forks out in two directions: to Delimara and Xrobb il-Ghagin due south-east and to Marsaxlokk village due south-west. A British-period fort occupying the highest point of the elongated hill further south along· the first road also carries the same place name. The lower and more compact hill on which the excavations have been conducted is called 'Ta' Berikka' , but since it is so close to the above-mentioned church (only 50 m to the north) the tradition of calling it Tas-Silg is now well established and there is no sense in changing it. The site has a commanding view of the Marsaxlokk harbour to the south and overlooks two other bays, Marsascala and St Thomas's bay, to the north-east. On all sides the slope is broken up by man-made terraced fields There is no doubt that the topography of the site must have been a determining factor in its choice for the establishment of a religious centre in the Temple period of Maltese pehistory (3000--2500 BC), though one must keep in mind that close to Tas-Silg there are three other prehistoric temple sites. each one with a completely different topography. The Temple people were quite introverted in their cultural isolation and do not seem to have been much interested in seafaring and in the outside world. The situation changed radically in the following age, the Bronze Age. when the island was occupied by people who set up villages on naturally defensible hilltops, occasionally fortifying them with artificial ramparts. The Tas-Silg hill with its temple ruins was occupied by these people, but it is not as yet clear for what purpose. The scenario changed again in historical times when the central and western Mediterranean started to be parcelled out among the commercial powers originating in the eastern Mediterranean. The Greeks do not seem to have even tried 10 colonize Malta as they did in neighbouring Sicily. The Phoenicians, however, did occupy the island, apparently through a slow process of peaceful penetration and eventual political and cultural assimi lation. It was in this period that the ruins of the megalithic temple were transformed into a Phoenician extraurban shrine dedicated to Astarte, which in time expanded into a full y-fledged sanctuary with an international reputation. The last chapter in the millennia- long history of the site was written when the colonnaded courtyard in front of the old temple was transformed into an early Christian church. Any use made of the site in the following Arab period is, once again, poorly understood.peer-reviewe

Discrete Spacetime and Relativistic Quantum Particles

We study a single quantum particle in discrete spacetime evolving in a causal way. We see that in the continuum limit any massless particle with a two dimensional internal degree of freedom obeys the Weyl equation, provided that we perform a simple relabeling of the coordinate axes or demand rotational symmetry in the continuum limit. It is surprising that this occurs regardless of the specific details of the evolution: it would be natural to assume that discrete evolutions giving rise to relativistic dynamics in the continuum limit would be very special cases. We also see that the same is not true for particles with larger internal degrees of freedom, by looking at an example with a three dimensional internal degree of freedom that is not relativistic in the continuum limit. In the process we give a formula for the Hamiltonian arising from the continuum limit of massless and massive particles in discrete spacetime.Comment: 6 page

Universal Sound Absorption in Amorphous Solids: A Theory of Elastically Coupled Generic Blocks

Glasses are known to exhibit quantitative universalities at low temperatures, the most striking of which is the ultrasonic attenuation coefficient 1/Q. In this work we develop a theory of coupled generic blocks with a certain randomness property to show that universality emerges essentially due to the interactions between elastic blocks, regardless of their microscopic nature.Comment: (Revised) 16 pages, 2 figures. To appear in Journal of Non-Crystalline Solid

Causal Fermions in Discrete Spacetime

In this paper, we consider fermionic systems in discrete spacetime evolving with a strict notion of causality, meaning they evolve unitarily and with a bounded propagation speed. First, we show that the evolution of these systems has a natural decomposition into a product of local unitaries, which also holds if we include bosons. Next, we show that causal evolution of fermions in discrete spacetime can also be viewed as the causal evolution of a lattice of qubits, meaning these systems can be viewed as quantum cellular automata. Following this, we discuss some examples of causal fermionic models in discrete spacetime that become interesting physical systems in the continuum limit: Dirac fermions in one and three spatial dimensions, Dirac fields and briefly the Thirring model. Finally, we show that the dynamics of causal fermions in discrete spacetime can be efficiently simulated on a quantum computer.Comment: 16 pages, 1 figur

The initial stages of cave formation: Beyond the one-dimensional paradigm

The solutional origin of limestone caves was recognized over a century ago, but the short penetration length of an undersaturated solution made it seem impossible for long conduits to develop. This is contradicted by field observations, where extended conduits, sometimes several kilometers long, are found in karst environments. However, a sharp drop in the dissolution rate of CaCO_3 near saturation provides a mechanism for much deeper penetration of reactant. The notion of a "kinetic trigger" - a sudden change in rate constant over a narrow concentration range - has become a widely accepted paradigm in speleogenesis modeling. However, it is based on one-dimensional models for the fluid and solute transport inside the fracture, assuming that the dissolution front is planar in the direction perpendicular to the flow. Here we show that this assumption is incorrect; a planar dissolution front in an entirely uniform fracture is unstable to infinitesimal perturbations and inevitably breaks up into highly localized regions of dissolution. This provides an alternative mechanism for cave formation, even in the absence of a kinetic trigger. Our results suggest that there is an inherent wavelength to the erosion pattern in dissolving fractures, which depends on the reaction rate and flow rate, but is independent of the initial roughness. In contrast to one-dimensional models, two-dimensional simulations indicate that there is only a weak dependence of the breakthrough time on kinetic order; localization of the flow tends to keep the undersaturation in the dissolution front above the threshold for non-linear kinetics.Comment: to be published in Earth and Planetary Science Letter

Binary time series generated by chaotic logistic maps

This paper examines stochastic pairwise dependence structures in binary time series obtained from discretised versions of standard chaotic logistic maps. It is motivated by applications in communications modelling which make use of so-called chaotic binary sequences. The strength of non-linear stochastic dependence of the binary sequences is explored. In contrast to the original chaotic sequence, the binary version is non-chaotic with non-Markovian non-linear dependence, except in a special case. Marginal and joint probability distributions, and autocorrelation functions are elicited. Multivariate binary and more discretised time series from a single realisation of the logistic map are developed from the binary paradigm. Proposals for extension of the methodology to other cases of the general logistic map are developed. Finally, a brief illustration of the place of chaos-based binary processes in chaos communications is given.Binary sequence; chaos; chaos communications; dependence; discretisation; invariant distribution; logistic map; randomness

External tank aerothermal design criteria verification

If a Space Shuttle Main Engine (SSME) fails during the initial 160 seconds of the Shuttle flight, a return-to-launch-site maneuver will be implemented. The period of concern for this task is the pitch-around maneuver when the vehicle is flying backward. The intent of this report is to identify and define the flowfield at the most critical locations from an environment perspective. The solution procedure used to predict the plume heating rates involves both computational analysis and engineering modeling

Equity of access to adult hospice inpatient care within north-west England.

There is a growing debate about the question of equity of access to hospice and palliative care services. Even countries with relatively well developed palliative care systems are considered to have problems of access and inequity of provision. Despite these concerns, we still lack a relevant evidence base to serve as a guide to action. We present an analysis of access to adult hospice inpatient provision in the north-west region of England that employs Geographical Information Systems (GIS). Measures of the possible demand for, and supply of, hospice inpatient services are used to determine the potential accessibility of cancer patients, assessed at the level of small areas (electoral wards). Further, the use of deprivation scores permits an analysis of the equity of access to adult inpatient hospice care, leading to the identification of areas where additional service provision may be warranted. Our research is subject to a number of caveats�it is limited to inpatient hospice provision and does not include other kinds of inpatient and community-based palliative care services. Likewise, we recognise that not everyone with cancer will require palliative care and also that palliative care needs exist among those with nonmalignant conditions. Nevertheless, our methodology is one that can also be applied more generally

Mechanical Characterization of Torsional Micropaddles Using Atomic Force Microscopy

The reference cantilever method is shown to act as a direct and simple method for determination of torsional spring constant. It has been applied to the characterization of micropaddle structures similar to those proposed for resonant functionalized chemical sensors and resonant thermal detectors. It is shown that this method can be used as an effective procedure to characterize a key parameter of these devices and would be applicable to characterization of other similar MEMS/NEMS devices such as micromirrors. In this study, two sets of micropaddles are manufactured (beams at centre and offset by 2.5 μm) by using LPCVD silicon nitride as a substrate. The patterning is made by direct milling using focused ion beam. The torsional spring constant is achieved through micromechanical analysis via atomic force microscopy. To obtain the gradient of force curve, the area of the micropaddle is scanned and the behaviour of each pixel is investigated through an automated developed code. The experimental results are in a good agreement with theoretical results