The first-order spectral flow of the odd signature operator on a manifold with boundary

AbstractIn this paper we study spectral flow for paths of signature operators associated to analytic paths of flat connections on an odd-dimensional manifold with boundary. We provide a topological method for computing the “first order” spectral flow using cup products

Lake and River Ice Investigations in Northern Manitoba Using Airborne SAR Imagery

Multichannel airborne SAR data were collected over northern Manitoba in April 1989 and January 1990. During the week of the SAR flights, several reconnaissance helicopter flights were undertaken, and ground calibration sites were visited to collect ice, snow, and water data. A total of six SAR image passes were flown in April 1989 and seven in January 1990, in order to collect a data set with numerous incidence angle, frequency, polarization, and look direction combinations. The data have been qualitatively assessed, with specific emphasis on C-band horizontally polarized imagery - the proposed SAR configuration for Radarsat. Results of the analysis have shown that airborne SAR can be used to identify various freshwater ice features, such as juxtaposition ice, refrozen slush, river ice runs, and lake ice. Open water leads were also successfully identified. A careful interpretation of the airborne SAR imagery in conjunction with the ground truth data has shown that the unusually bright returns characterizing the Burntwood River and the west portion of Split Lake were caused by a layer of refrozen slush that was generated during the initial formation of the ice cover. Although the results reported here focused exclusively on a qualitative analysis of C-HH data, preliminary analysis of the digital data suggests that changes in frequency and polarization produce measurable differences and can be used to develop classification algorithms for freshwater ice.Key words: synthetic aperture radar, fresh water iceMots clés: radar à antenne synthétique, glace d’eau douc

The D234 action for light quarks

We investigate a new light fermion action (the ``D234'' action), which is accurate up to \O(a^3) and tadpole-improved \O(a \alpha_s) errors. Using D234 with Symanzik- and tadpole-improved glue we find evidence that continuum results for the quenched hadron spectrum (pion, rho and nucleon) can be obtained on coarse lattices.Comment: Latex, 4 pages, submitted to Lattice '95 proceeding

On O(1) contributions to the free energy in Bethe Ansatz systems: the exact g-function

We investigate the sub-leading contributions to the free energy of Bethe Ansatz solvable (continuum) models with different boundary conditions. We show that the Thermodynamic Bethe Ansatz approach is capable of providing the O(1) pieces if both the density of states in rapidity space and the quadratic fluctuations around the saddle point solution to the TBA are properly taken into account. In relativistic boundary QFT the O(1) contributions are directly related to the exact g-function. In this paper we provide an all-orders proof of the previous results of P. Dorey et al. on the g-function in both massive and massless models. In addition, we derive a new result for the g-function which applies to massless theories with arbitrary diagonal scattering in the bulk.Comment: 28 pages, 2 figures, v2: minor corrections, v3: minor corrections and references adde

Rotating Shadowband Spectroradiometer (RSS) Handbook

The rotating shawdowband spectroradiometer (RSS) implements the same automated shadowbanding technique used by the multifilter rotating shadowband radiometer (MFRSR), and so it too provides spectrally-resolved, direct-normal, diffuse-horizontal, and total-horizontal irradiances, and can be calibrated in situ via Langley regression. The irradiance spectra are measured simultaneously at all spectral elements (pixels) in 360-nm to 1050-nm range