122 research outputs found
A View from Melrose
An essay by President Vivian A. Bull: Thirteen Years in Review
Recent glacial recession in the Rwenzori Mountains of East Africa due to rising air temperature
Based on field surveys and analyses of optical spaceborne images (LandSat5, LandSat7), we report recent decline in the areal extent of glaciers in the Rwenzori Mountains of East Africa from 2.01 +/- 0.56 km(2) in 1987 to 0.96 +/- 0.34 km(2) in 2003. The spatially uniform loss of glacial cover at lower elevations together with meteorological trends derived from both station and reanalysis data, indicate that increased air temperature is the main driver. Clear trends toward increased air temperatures over the last four decades of similar to 0.5 degrees C per decade exist without significant changes in annual precipitation. Extrapolation of trends in glacial recession since 1906 suggests that glaciers in the Rwenzori Mountains will disappear within the next two decades
Climate change and the aquatic ecosystems of the Rwenzori Mountains, Uganda
The Rwenzori Mountains are home to one of the last remaining tropical icefields
outside of the Andes. Over the last century, equatorial icefields of the East
African highlands have been steadily shrinking but the precise climate tropical
alpine glaciers remain unclear. More than a decade had passed since the last
detailed measurements of glacial cover were made in the Rwenzori Mountains.
Recent evidence from Kilimanjaro suggests that its icecap will disappear entirely
by the year 2020(1). The Rwenzori glaciers contribute meltwater flows to aquatic
ecosystems of the Rwenzori Mountains National Park, a Word Heritage Site
featuring spectacular, rare Afroalpine flora and fauna, and are headwaters of the
River Nile. With the overall aim of assessing the impact of recent climate change
on alpine aquatic ecosystems of the Rwenzori Mountains, a collaborative,
international research team led by the University College London (United
Kingdom) and Makerere University (Uganda), and involving the Institut für
Geographie from the University of Innsbruck (Austria) and Water Resources
Management Department (Uganda) was assembled in order to pursue three
primary scientific objectives:
• to assess the magnitude of current glacial recession;
• to assess the impact of glacial recession on alpine riverflow; and
• to assess recent environmental change from observational datasets and
available, environmental archives stored in lake sediment and glacial ice
The use of an e-learning constructivist solution in workplace learning
We wished to investigate whether an e-learning approach which uses constructivist principles can be successfully applied to train employees in a highly specialised skill thought to require expert individuals and extensive prolonged training. The approach involved the development of an e-learning package which included simulations and interactivity, then experimental testing in a case study workplace environment with the collection of both quantitative and qualitative data to assess the effectiveness of the package. Our study shows that this e-learning strategy improved the skills of the inexperienced
operator significantly. We therefore propose that such programmes could be used as a work based training aid and used as a model system for the training of employees in complex skilled tasks in the workplace. This research demonstrates that the e-learning can be applied outside the traditional learning environment to train unskilled employees to undertake complex practical tasks which traditionally would involve prohibitively expensive instruction. This work also illustrates that simulations and interactivity are powerful tools in the design of successful e-learning packages in preparing learners for real world practical situations. Finally this study shows that workplace learners can be better served by elearning environments rather than conventional training as they allow asynchronous learning and private study which are valued by employees who have other demands on their time and are more comfortable receiving tuition privately Relevance to industry: E-learning using constructivist principles, and incorporating simulations and interactivity can be used successfully in the training of highly specialised and skilled tasks required in the
modern workplace
Current advances on Talbot–Lau x-ray imaging diagnostics for high energy density experiments (invited)
Producción CientÃficaTalbot–Lau x-ray interferometry is a refraction-based diagnostic that can map electron density gradients through phase-contrast methods. The Talbot–Lau x-ray deflectometry (TXD) diagnostics have been deployed in several high energy density experiments. To improve diagnostic performance, a monochromatic TXD was implemented on the Multi-Tera Watt (MTW) laser using 8 keV multilayer mirrors (Δθ/θ = 4.5%-5.6%). Copper foil and wire targets were irradiated at 1014–1015 W/cm2. Laser pulse length (∼10 to 80 ps) and backlighter target configurations were explored in the context of Moiré fringe contrast and spatial resolution. Foil and wire targets delivered increased contrast <30%. The best spatial resolution (<6 μm) was measured for foils irradiated 80° from the surface. Further TXD diagnostic capability enhancement was achieved through the development of advanced data postprocessing tools. The Talbot Interferometry Analysis (TIA) code enabled x-ray refraction measurements from the MTW monochromatic TXD. Additionally, phase, attenuation, and dark-field maps of an ablating x-pinch load were retrieved through TXD. The images show a dense wire core of ∼60 μm diameter surrounded by low-density material of ∼40 μm thickness with an outer diameter ratio of ∼2.3. Attenuation at 8 keV was measured at ∼20% for the dense core and ∼10% for the low-density material. Instrumental and experimental limitations for monochromatic TXD diagnostics are presented. Enhanced postprocessing capabilities enabled by TIA are demonstrated in the context of high-intensity laser and pulsed power experimental data analysis. Significant advances in TXD diagnostic capabilities are presented. These results inform future diagnostic technique upgrades that will improve the accuracy of plasma characterization through TXD
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