A dual telescope for spectroheliography in the extreme ultra-violet

Dual reflecting telescope design for ultraviolet spectroheliograph

Low-density polybenzimidazole foams for thermal insulation and fire protection

Fire-resistant and nonsmoking foam can be prepared in desirable density range of 24 to 50 kg/cu m by controlled thermal crosslinking of polybenzimidazole prepolymer. Reproducible foams of specific density can be produced by controlling volative content and melting temperature of prepolymer

Solar Flare X-ray Source Motion as a Response to Electron Spectral Hardening

Context: Solar flare hard X-rays (HXRs) are thought to be produced by nonthermal coronal electrons stopping in the chromosphere, or remaining trapped in the corona. The collisional thick target model (CTTM) predicts that sources produced by harder power-law injection spectra should appear further down the legs or footpoints of a flare loop. Therefore, hardening of the injected power-law electron spectrum during flare onset should be concurrent with a descending hard X-ray source. Aims: To test this implication of the CTTM by comparing its predicted HXR source locations with those derived from observations of a solar flare which exhibits a nonthermally-dominated spectrum before the peak in HXRs, known as an early impulsive event. Methods: HXR images and spectra of an early impulsive C-class flare were obtained using the Ramaty High-Energy Solar Spectroscopic Imager (RHESSI). Images were reconstructed to produce HXR source height evolutions for three energy bands. Spatially-integrated spectral analysis was performed to isolate nonthermal emission, and to determine the power-law index of the electron injection spectrum. The observed height-time evolutions were then fit with CTTM-based simulated heights for each energy. Results: A good match between model and observed source heights was reached, requiring a density model that agreed well with previous studies of flare loop densities. Conclusions: The CTTM has been used to produce a descent of model HXR source heights that compares well with observations of this event. Based on this interpretation, downward motion of nonthermal sources should indeed occur in any flare where there is spectral hardening in the electron distribution during a flare. However, this would often be masked by thermal emission associated with flare plasma pre-heating.Comment: 8 pages, 5 figure

The spectral content of SDO/AIA 1600 and 1700 \AA\ filters from flare and plage observations

The strong enhancement of the ultraviolet emission during solar flares is usually taken as an indication of plasma heating in the lower solar atmosphere caused by the deposition of the energy released during these events. Images taken with broadband ultraviolet filters by the {\em Transition Region and Coronal Explorer} (TRACE) and {\em Atmospheric Imaging Assembly} (AIA 1600 and 1700~\AA) have revealed the morphology and evolution of flare ribbons in great detail. However, the spectral content of these images is still largely unknown. Without the knowledge of the spectral contribution to these UV filters, the use of these rich imaging datasets is severely limited. Aiming to solve this issue, we estimate the spectral contributions of the AIA UV flare and plage images using high-resolution spectra in the range 1300 to 1900~\AA\ from the Skylab NRL SO82B spectrograph. We find that the flare excess emission in AIA 1600~\AA\ is { dominated by} the \ion{C}{4} 1550~\AA\ doublet (26\%), \ion{Si}{1} continua (20\%), with smaller contributions from many other chromospheric lines such as \ion{C}{1} 1561 and 1656~\AA\ multiplets, \ion{He}{2} 1640~\AA, \ion{Si}{2} 1526 and 1533~\AA. For the AIA 1700~\AA\ band, \ion{C}{1} 1656~\AA\ multiplet is the main contributor (38\%), followed by \ion{He}{2} 1640 (17\%), and accompanied by a multitude of other, { weaker} chromospheric lines, with minimal contribution from the continuum. Our results can be generalized to state that the AIA UV flare excess emission is of chromospheric origin, while plage emission is dominated by photospheric continuum emission in both channels.Comment: Accepted for publication in ApJ Skylab NRL SO82B data used in this work available at http://dx.doi.org/10.5525/gla.researchdata.68

Constraining Phosphorus in Surface Waters of the New York City Watershed: Dairy Farm Resource Use and Profitability

The New York City Watershed Agricultural Program seeks to reduce the potential for phosphorus movement from farms to surface waters. A "phosphorus index for site evaluation" (P-index) provides planners in the New York City Watershed Agricultural Program with a tool for identifying individual farm business, phosphorus related problems, and evaluating solutions. A linear programming model is employed to examine dairy farm resource use and profitability, with the P-index used to impose phosphorus movement constraints. Results indicate dramatic differences in farm resource use and farm business profitability depending on the level of the P-index. Small changes in the target index level result in large shifts in optimal resource use and business profitability. These differences illustrate that restrictions on phosphorus movement from land to surface waters potentially have major impacts on resource use and farm profitability in the New York City Watershed

Eyes on the enterprise: problematising the concept of a teaching-research nexus in UK higher education

Existing research into the relationship between teaching and research in higher education is mainly normative and atheoretical, resulting in assumptions of a close and beneficial connection between them. We problematise the idea of a nexus by undertaking a critical examination of the concept through the lens of educational ideologies to theorise the changes over time that shape the ways teaching and research are practised. Two hundred seven academic staff in the Humanities and Social Sciences were surveyed in 10 universities in England and Wales; the universities were identified as having strength in teaching, research, or in both. Along with analysis of interviews with senior managers at these universities, findings suggest that systemic forces which separate teaching and research are evident in institutional contexts with implications for the idea of a nexus. While the nexus may exist in theory, in practice, we argue that teaching and research can be pulled in different directions by institutional priorities. Furthermore, in institutions which adopt an enterprise ideology, there are signs of a nascent nexus emerging between research and innovation