1,171 research outputs found
Metastatic Gas gangrene and Colonic Perforation: a case report
Clostridium septicum myonecrosis is associated with diabetes, colorectal and haematological malignancies. We present a case of metastatic myonecrosis in a diabetic patient with a perforated caecal tumour. The literature since 1989 is reviewed and 28 cases of Clostridium septicum myonecrosis are discussed
Measuring the quantum efficiency of single radiating dipoles using a scanning mirror
Using scanning probe techniques, we show the controlled manipulation of the
radiation from single dipoles. In one experiment we study the modification of
the fluorescence lifetime of a single molecular dipole in front of a movable
silver mirror. A second experiment demonstrates the changing plasmon spectrum
of a gold nanoparticle in front of a dielectric mirror. Comparison of our data
with theoretical models allows determination of the quantum efficiency of each
radiating dipole.Comment: 4 pages, 4 figure
A 2000 year record of palaeofloods in a volcanically-reset catchment: Whanganui River, New Zealand
Palaeofloods in the Whanganui River, North Island, New Zealand are investigated using floodplain sedimentary archives at two locations in the lower Whanganui catchment. The ca. AD 232 Taupo volcanic eruption transformed the lower valley of the Whanganui River, emplacing a substantial volume of volcanogenic mass flow material and providing a new starting point for subsequent alluvial sedimentation. At Atene a high–resolution archive of flood sediments is preserved in a valley meander cutoff in the lower reaches of the Whanganui Gorge, where a ~9 m core was extracted. At Crowley House further down valley, two ~5 m cores were also extracted from a terrace-confined floodplain. Organic material from these cores allows the timing of floods at these sites to be constrained using 11 radiocarbon dates (ten from Atene, one from Crowley House). Flood magnitudes are reconstructed using XRF core-scanned geochemistry as a proxy for flood unit grain size. An age-depth model at Atene identifies three distinct phases of sedimentation with above average flood activity recorded at 1450–1125, 950, 650–500, and 400–325 cal. yr BP, which can be linked to the El Niño Southern Oscillation (ENSO) and strengthening of the Southern Hemisphere Westerly Wind circulation. Large floods also cluster in the late 1800s, reflecting a combination of enhanced storminess and land cover change, which also resulted in deeper erosion of regolith in the catchment, revealed by cosmogenic analysis at Crowley House. Climatic and non-climatic drivers are responsible for floods in the Whanganui catchment over the past ~2000 years, with the largest floods occurring during La Niña and positive Southern Annular Mode conditions. The timing of the largest single flood in the Whanganui in this period is consistent with the volcanic-resetting event itself of AD 232. This study demonstrates the close relationship between regional climate variability in the south-western Pacific Ocean and the occurrence of extreme floods in New Zealand, and the importance of using multi-centennial length hydrological series for effective flood risk assessment
The s Process: Nuclear Physics, Stellar Models, Observations
Nucleosynthesis in the s process takes place in the He burning layers of low
mass AGB stars and during the He and C burning phases of massive stars. The s
process contributes about half of the element abundances between Cu and Bi in
solar system material. Depending on stellar mass and metallicity the resulting
s-abundance patterns exhibit characteristic features, which provide
comprehensive information for our understanding of the stellar life cycle and
for the chemical evolution of galaxies. The rapidly growing body of detailed
abundance observations, in particular for AGB and post-AGB stars, for objects
in binary systems, and for the very faint metal-poor population represents
exciting challenges and constraints for stellar model calculations. Based on
updated and improved nuclear physics data for the s-process reaction network,
current models are aiming at ab initio solution for the stellar physics related
to convection and mixing processes. Progress in the intimately related areas of
observations, nuclear and atomic physics, and stellar modeling is reviewed and
the corresponding interplay is illustrated by the general abundance patterns of
the elements beyond iron and by the effect of sensitive branching points along
the s-process path. The strong variations of the s-process efficiency with
metallicity bear also interesting consequences for Galactic chemical evolution.Comment: 53 pages, 20 figures, 3 tables; Reviews of Modern Physics, accepte
Assessment of Metal Mining-Contaminated River Sediments in England and Wales
This report reviews how sediments and floodplain soils have been contaminated by abandoned metal mines and recommends what the Environment Agency should do about this issue
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