5 research outputs found
Current thinking about the management of recurrent pleomorphic adenoma of the parotid: a structured review
No full textPleomorphic adenoma is the most common tumour of the parotid gland, and can recur after excision. Recurrent pleomorphic adenoma can be a challenge to treat, and has variable outcomes. The aim of this review was to summarise current thinking in its management, which may be helpful to clinical teams and could improve patients’ health-related quality of life. We searched several online databases using the key terms pleomorphic adenoma, recurrent pleomorphic adenoma, parotid gland tumours, parotid surgery, radiotherapy and parotid pleomorphic adenoma, and parotid surgery outcomes. Information collected included sample size, recurrence rate, condition of the facial nerve, type of operation, adjuvant treatments associated with recurrence, and clinical outcome. We screened 2301 papers, of which 49 were eligible. There was no consensus among authors about management. There are few if any randomised studies, and so conclusions in most papers were based on coherent arguments. Pleomorphic adenomas of the parotid tend to recur after long intervals, with a propensity towards multifocal disease, and the risk of recurrence (which depends on the initial surgical technique) is higher when the initial operation was done at a young age, after enucleation, and if the initial margins were invaded. Published conclusions suggest that the accepted management varies from observation in selected cases to total parotidectomy with or without postoperative radiotherapy
Hydrogen Zoning in Olivine from Kimberlites Based on Coupled FTIR and SIMS Analyses: Significance for H2O Distribution in the Lithospheric Mantle and H2O Concentrations in Kimberlite Melts
No full textKimberlite melts are widely considered to be enriched in volatiles, both CO and HO. Yet, estimated HO concentrations in primitive kimberlites vary between 3.0 and 12 wt %, and it is unclear whether these variations are a true reflection of variable HO in their mantle sources. The main problem rests with the origin of serpentine, the main HO host in kimberlite rocks, and specifically, whether it derives from magmatic and/or crustal fluids. To obtain estimates of primary HO contents in kimberlite melts, we have examined the systematics of proton incorporation in olivine point defects (referred as H) in grains from eight representative kimberlites from Africa, Canada and Greenland. These kimberlites show highly variable groundmass and, therefore, melt compositions and include varieties enriched in serpentine, carbonate and/or phlogopite. Olivine grains are strongly zoned in major and minor elements based on BSE images and EPMA analysis and include mantle-derived xenocrystic cores and magmatic rims. FTIR maps and profiles show that the olivine cores are zoned with HO decreasing outward due to diffusive loss most likely triggered by decompression and related HO loss from the transporting kimberlite melt after xenocryst entrainment. The central portions of the cores exhibit homogeneous HO contents representative of mantle values. A combination of Al-in-olivine thermometry with appropriate geothermal gradients and HO determinations from SIMS analyses (from 9 to 241 μg/g across the entire sample set) shows similar systematics to those of olivine in mantle xenoliths from the same localities. HO analyses of olivine cores in kimberlites are hence valuable to systematically examine the vertical distribution of HO in the lithospheric mantle traversed by kimberlites. The magmatic rims examined by SIMS invariably show low HO contents (<50 μg/g but mostly ≤20 μg/g) with very limited within-sample variation regardless of olivine major-minor element chemistry and groundmass composition. Experimentally derived hydrogen partition coefficients yield ≤1 wt % of HO in the corresponding melts, values that probably reflect post-emplacement re-equilibration in the upper crust rather than equilibrium conditions during crystallisation. These low HO contents reflect, at least in part, exsolution of C–O–H fluids during kimberlite ascent. The implication is that kimberlite melts contain insufficient HO to crystallise the large amount (up to 50 vol %) of serpentine commonly observed in kimberlites. Serpentine rather requires contributions by crustal fluids and/or deeply exsolved kimberlite-related fluids that percolate upwards along the pipe- or dike-like emplacement structures, modifying the composition of previously crystallised kimberlites.This project was funded by the Swiss National Foundation (Ambizione fellowship no. PZ00P2_180126/1 to A.G.; grant no. 200020-196927 to J.H. and N.B.G.) and ETH Zurich (ETH Grant to M.W.S. and A.G.)
Great Footed Hawk, Falco Peregrinus
No full textThis item is plate 16 from Audubon’s The Birds of America; from Original Drawings, London: Published by the Author, 1827-1838. It is a single framed plate from that work. The item measures about 37.75 x 24.50 inches in the frame. It is a hand-colored engraving, etching, and aquatint. The work contains a male and female Peregrine Falcon eating a Green-Winged Teal and Gadwal. The print bears a variety of marginalia: upper left, “No. 4”; upper right, “PLATE 16 [Arabic]”; lower left, “Drawn from Nature and Published by John J. Audubon. F.R.S.E. M.W.S.”; lower right “Engraved, Printed & Coloured by R. Havell & Son London.”
The hand-colored, engraved plates, which comprise The Birds of America, are based on original watercolors painted by Audubon. Three engravers are credited with collaborating with Audubon to produce the finished project. They are William H. Lizars (1788-1859), Robert Havell, Sr. (1769-1832), and Robert Havell, Jr. (1793-1878).https://collected.jcu.edu/specialcollectionsimages/1000/thumbnail.jp
