Some properties of generalized connections in quantum gravity

The quantum completion of the space of connections in a manifold can be seen as the set of all morphisms from the groupoid of the edges of the manifold to the (compact) gauge group. This algebraic construction generalizes the analogous description of the gauge-invariant quantum configuration space of Ashtekar and Isham. We present a description of the groupoid approach which brings the gauge-invariant degrees of freedom to the foreground, thus making the action of the gauge group more transparent.Comment: LaTeX, 11 pages. Submitted to the on-line proceedings of the Ninth Marcel Grossmann Meeting (Rome, July 2000). Talk based on hep-th/001120

Functorial Aspects of the Space of Generalized Connections

We give a description of the category structure of the space of generalized connections, an extension of the space of connections that plays a central role in loop quantum gravity.Comment: 7 pages. To appear in Proceedings of the Lusofona Workshop on Quantum Gravity and Noncommutative Geometry, Lisbon, July 200

Development of polymeric anepectic meshes: Auxetic metamaterials with negative thermal expansion

This paper reports the application of additive manufacturing technology to fabricate bi-dimensional lightweight composite meshes capable of demonstrating auxetic properties (negative Poisson's ratio (NPR)) in combination with negative thermal expansion (NTE) behaviour, using as constituent materials polymers that do not exhibit NTE behaviour. To describe the combination of NPR and NTE characteristics, the designation of 'anepectic' is being proposed. Each mesh, obtained from varying either the material combination or the design parameters, was tested on a heated silicone bath to study the effects of the different combinations on the coefficient of thermal expansion (CTE). It was found that all meshes studied demonstrated a successful combination of NPR and NTE behaviours, and it was revealed that there is a possibility to tailor the meshes to activate the NTE behaviour within a chosen range of temperatures. For an extreme case, a Poisson's ratio of-0.056, along with a CTE of-1568 × 10 -6 K -1 has been achieved.authorsversionpublishe