Second order formalism in Poincare gauge theory

Changing the set of independent variables of Poincare gauge theory and considering, in a manner similar to the second order formalism of general relativity, the Riemannian part of the Lorentz connection as function of the tetrad field, we construct theories that do not contain second or higher order derivatives in the field variables, possess a full general relativity limit in the absence of spinning matter fields, and allow for propagating torsion fields in the general case. A concrete model is discussed and the field equations are reduced by means of a Yasskin type ansatz to a conventional Einstein-Proca system. Approximate solutions describing the exterior of a spin polarized neutron star are prsented and the possibility of an experimental detection of the torsion fields is briefly discussed.Comment: final version, to appear in IJMP

Electromagnetic lattice gauge invariance in two-dimensional discrete-time quantum walks

Gauge invariance is one of the more important concepts in physics. We discuss this concept in connection with the unitary evolution of discrete-time quantum walks in one and two spatial dimensions, when they include the interaction with synthetic, external electromagnetic fields. One introduces this interaction as additional phases that play the role of gauge fields. Here, we present a way to incorporate those phases, which differs from previous works. Our proposal allows the discrete derivatives, that appear under a gauge transformation, to treat time and space on the same footing, in a way which is similar to standard lattice gauge theories. By considering two steps of the evolution, we define a density current which is gauge invariant and conserved. In the continuum limit, the dynamics of the particle, under a suitable choice of the parameters, becomes the Dirac equation, and the conserved current satisfies the corresponding conservation equation

1. The Advent of Modern Democracy

Everywhere there was a strong tendency to modify the concepts of political liberalism into a justification of democracy. By and large, this was not the result of the creation of a completely new political theory. The advocates of democracy tended to justify their doctrine with natural-rights theories from the Enlightenment, with a utilitarianism reminiscent of John Stuart Mill, with deductions drawn from the romantic glorification of the individual, or with appeals to the record of the United States. In general, they took over the concepts of the middle-class liberalism of the nineteenth century. However, the very logic of the liberal position in an increasingly industrialized world forced democrats to advocate the removal of many of those limitations on popular participation in government which liberals earlier had thought necessary. With victory apparently in sight in the years 1871-1914, democracy can be studied through its acts, in the difficult task of putting into practice under widely divergent conditions those general concepts which had been forged in an earlier age. In the process strongly egalitarian institutions were developed which became identified with democracy in the minds of most Westerners. It is in the observations of this process that we can test the definition of democracy as government responsible to the will of the people. [excerpt

mLearning, development and delivery : creating opportunity and enterprise within the HE in FE context

This research project was funded by ESCalate in 2006-7 to support Somerset College in developing the curriculum, as well as widening participation via the use of mobile communications technologies such as mp3 players and mobile phones. The Project represents a highly topical and timely engagement with the opportunities for learning provided by the burgeoning use of mobile computing/ communications devices. Activities bring together colleagues from Teacher Education and Multimedia Computing in an innovative approach to designing for and delivering the curriculum. The Project addresses pedagogic issues and also vitally involves current and future learners, providing them with a new context for skills development and entrepreneurship. Anticipated outcomes include informed development of new HE modules and professional CPD activities which address the skills and context of this emerging approach to delivering the curriculum. The Project also intends to trial and evaluate the use of mobile technologies to support a blended learning approach to programme delivery and the development of a FD module which could be delivered via a mobile computing device. An interim report and a final project report are available as Word and PDF file

Geologic applications of thermal-inertia mapping from satellite

In the Powder River Basin, Wyo., narrow geologic units having thermal inertias which contrast with their surroundings can be discriminated in optimal images. A few subtle thermal inertia anomalies coincide with areas of helium leakage believed to be associated with deep oil and gas concentrations. The most important results involved delineation of tectonic framework elements some of which were not previously recognized. Thermal and thermal inertia images also permit mapping of geomorphic textural domains. A thermal lineament appears to reveal a basement discontinuity which involves the Homestake Mine in the Black Hill, a zone of Tertiary igneous activity and facies control in oil producing horizons. Applications of these data to the Cabeza Prieta, Ariz., area illustrate their potential for igneous rock type discrimination. Extension to Yellowstone National Park resulted in the detection of additional structural information but surface hydrothermal features could not be distinguished with any confidence. A thermal inertia mapping algorithm, a fast and accurate image registration technique, and an efficient topographic slope and elevation correction method were developed

Ensuring Cyber-Security in Smart Railway Surveillance with SHIELD

Modern railways feature increasingly complex embedded computing systems for surveillance, that are moving towards fully wireless smart-sensors. Those systems are aimed at monitoring system status from a physical-security viewpoint, in order to detect intrusions and other environmental anomalies. However, the same systems used for physical-security surveillance are vulnerable to cyber-security threats, since they feature distributed hardware and software architectures often interconnected by ‘open networks’, like wireless channels and the Internet. In this paper, we show how the integrated approach to Security, Privacy and Dependability (SPD) in embedded systems provided by the SHIELD framework (developed within the EU funded pSHIELD and nSHIELD research projects) can be applied to railway surveillance systems in order to measure and improve their SPD level. SHIELD implements a layered architecture (node, network, middleware and overlay) and orchestrates SPD mechanisms based on ontology models, appropriate metrics and composability. The results of prototypical application to a real-world demonstrator show the effectiveness of SHIELD and justify its practical applicability in industrial settings