Yang-Mills Fields and Riemannian Geometry

It is possible to define new, gauge invariant variables in the Hilbert space of Yang-Mills theories which manifestly implement Gauss' law on physical states. These variables have furthermore a geometrical meaning, and allow one to uncover further constraints physical states must satisfy. For gauge group $SU(2)$, the underlying geometry is Riemannian and based on the group $GL(3)$. The formalism allows also for the inclusion of static color sources and the extension to gauge groups $SU(N>2)$, both of which are discussed here.Comment: 22 PP., HARVMAC. MINOR TYPOS CORRECTED - FINAL VERSION, TO BE PUBLISHED IN NUCL. PHYS.

Nova Aquilae 1918 (V603 Aql) Faded by 0.44 mag/century from 1938-2013

We present the light curve of the old nova V603 Aql (Nova Aql 1918) from 1898-1918 and 1934-2013 using 22,721 archival magnitudes. All of our magnitudes are either in, or accurately transformed into, the Johnson $B$ and $V$ magnitude systems. This is vital because offsets in old sequences and the visual-to-$V$ transformation make for errors from 0.1-1.0 magnitude if not corrected. Our V603 Aql light curve is the first time that this has been done for any nova. Our goal was to see the evolution of the mass accretion rate on the century time scale, and to test the long-standing prediction of the Hibernation model that old novae should be fading significantly in the century after their eruption is long over. The 1918 nova eruption was completely finished by 1938 when the nova decline stopped, and when the star had faded to fainter than its pre-nova brightness of $B=11.43 \pm 0.03$ mag. We find that the nova light from 1938-2013 was significantly fading, with this being seen consistently in three independent data sets (the Sonneberg plates in $B$, the AAVSO $V$ light curve, and the non-AAVSO $V$ light curve). We find that V603 Aql is declining in brightness at an average rate of $0.44 \pm 0.04$ mag per century since 1938. This work provides remarkable confirmation of an important prediction of the Hibernation model.Comment: 13 pages, 1 figure, 2 electronic online data tables, Accepted for publication ApJLet

The Geoweb for community-based organizations: Tool development, implementation, and sustainability in an era of Google Maps

Recent advances in web-based geospatial tools (the Geoweb) show promise as low-cost and easy-to-use methods to support citizen participation. This research presents two case studies of Geoweb implementation set in community-based organizations in rural Quebec, Canada. When comparing the development and sustainability of each Geoweb tool, the implementation time frame plays a key role. Two implementation time frames are defined; a discrete, or ‘one-off’ time frame associated with lower resource requirements, and a continuous, or ongoing time frame, that has a higher total resource cost, but can fulfill a different set of goals than a discrete implementation

Role of tectonic stress in seepage evolution along the gas hydrate‐charged Vestnesa Ridge, Fram Strait

Methane expulsion from the world ocean floor is a broadly observed phenomenon known to be episodic. Yet the processes that modulate seepage remain elusive. In the Arctic offshore west Svalbard, for instance, seepage at 200–400 m water depth may be explained by ocean temperature‐controlled gas hydrate instabilities at the shelf break, but additional processes are required to explain seepage in permanently cold waters at depths \u3e1000 m. We discuss the influence of tectonic stress on seepage evolution along the ~100 km long hydrate‐bearing Vestnesa Ridge in Fram Strait. High‐resolution P‐Cable 3‐D seismic data revealed fine‐scale (\u3e10 m width) near‐vertical faults and fractures controlling seepage distribution. Gas chimneys record multiple seepage events coinciding with glacial intensification and active faulting. The faults document the influence of nearby tectonic stress fields in seepage evolution along this deepwater gas hydrate system for at least the last ~2.7 Ma

Threshold concepts: Impacts on teaching and learning at tertiary level

This project explored teaching and learning of hard-to-learn threshold concepts in first-year English, an electrical engineering course, leadership courses, and in doctoral writing. The project was envisioned to produce disciplinary case studies that lecturers could use to reflect on and refine their curriculum and pedagogy, thereby contributing to discussion about the relationship between theory and methodology in higher education research (Shay, Ashwin, & Case, 2009). A team of seven academics investigated lecturers’ awareness and emergent knowledge of threshold concepts and associated pedagogies and how such pedagogies can afford opportunities for learning. As part of this examination the lecturers also explored the role of threshold concept theory in designing curricula and sought to find the commonalities in threshold concepts and their teaching and learning across the four disciplines. The research highlights new ways of teaching threshold concepts to help students learn concepts that are fundamental to the disciplines they are studying and expand their educational experiences. Given that much of the international research in this field focuses on the identification of threshold concepts and debates their characteristics (Barradell, 2013; Flanagan, 2014; Knight, Callaghan, Baldock, & Meyer, 2013), our exploration of what happens when lecturers use threshold concept theory to re-envision their curriculum and teaching helps to address a gap within the field. By addressing an important theoretical and practical approach the project makes a considerable contribution to teaching and learning at the tertiary level in general and to each discipline in particular