1,721,254 research outputs found
Ruthenium and Tungsten isotopic composition of ocean island basalts and refrence materials
No full textThe dataset includes Ruthenium and Tungsten isotope data for mafic to ultramafic lava associated with the Hawaii, Réunion, Galápagos and Iceland plume systems. The data is supplemented by Ru isotope data for reference materials (OREAS 684) picrite derived from the upper mantle (Gönnern Quarry, Hessia) lherzolite preidotites (Eifel) and Eoarchean dunites (Isua, Greenland).
The data are supplementary to: Messling, Nils; Willbold, Matthias; Kallas, Leander; Elliott, Tim; Fitton, J. Godfrey; Müller, Thomas; Geist, Dennis (submitted) Core leakage revealed by Ru and W isotope systematics in ocean island basalts. Submitted to Natur
More images that yet fresh images beget
No full textIn this issue of Immunity, Dong et al. (2009) describe the protein crystal structure heterodimer of tapasin and ERp57, which helps visualize the function of these proteins in loading of peptide antigens onto MHC class I molecules as part of the peptide loading complex within the endoplasmic reticulum.<br/
Antigen processing movers and shakers
No full textMonitoring MHC-I dynamics upon binding to its chaperone TAPBPR helps us understand how optimal peptide sequences are selected for presentation and coordinated with release of the chaperone from the ternary peptide–MHC-I–TAPBPR complex
The 'chop-and-change' of MHC class I assembly
No full textCD8+ T cell recognition of peptides presented by major histocompatibility complex class I molecules is essential for effective antiviral and antitumor immune responses. How the repertoire of peptides is selected, shaped and presented is becoming increasingly clear
Molybdenum isotope variations in magmatic rocks
Full text linkThe application of Mo isotopes to study geodynamic processes is a rather new development that has gained considerable momentum over the past few years. Its redox-sensitivity causes significant mass-dependent isotope variability in low-temperature environments – mainly during weathering, sediment deposition and seafloor alteration. Potentially, these fractionated Mo isotope characteristics of surface materials could be used to identify recycled crustal components in mantle sources. Here we provide an overview of the first studies on mass-dependent isotope variations of Mo in igneous rocks and the Mo isotopic characteristics of major geochemical reservoirs before assessing the potential of Mo isotope variations as a new tracer in mantle geochemistry.Mass-dependent Mo isotope variations induced by magmatic differentiation are in general muted owing to the incompatibility of Mo in common igneous minerals. However, fractionation of Mo isotopes by hydrous silicate mineral phases has been suggested. Sulphide fractionation can potentially have a marked influence on the Mo isotope composition of evolving magmatic systems but does not appear to be a major influence due to the limited modal abundance of sulphide phases precipitated during differentiation. The largest Mo isotope variations in igneous systems reported so far are found in arc-related rocks. Currently available data suggest that the δ98/95Mo values (i.e. the 98Mo/95Mo ratio relative to the reference material NIST SRM 3134) measured in arc basalts are higher than those of the upper mantle. This offset appears to be linked to the addition of isotopically heavy slab-derived fluid to the arc melts, whereby heavier Mo isotopes become enriched in the fluid as a result of the slab-dehydration. In contrast, lighter δ98/95Mo compositions found in some arc-related lavas could be linked to geochemical tracers commonly associated with sediment melt contribution. Overall, mass balance considerations suggest that the recycled crustal material has a Mo isotope composition equal to or most likely lighter than that of fresh oceanic crust.Chondritic meteorites display a remarkably homogeneous δ98/95Mo of − 0.16 ± 0.02‰ suggesting a similar bulk composition for the inner solar system and thus the Earth. Residual Mo in the mantle after core formation is expected to be isotopically heavy but for temperatures in excess of 2500 K, typically proposed for core-mantle equilibration, the difference in δ98/95Mo of the mantle relative to chondrite is < 0.1‰. Analyses of Mo isotopes in mid-ocean ridge basalts suggest a slightly sub-chondritic composition of the depleted mantle (δ98/95Mo = − 0.21 ± 0.02‰). Similarly, late Archean komatiites yield slightly sub-chondritic δ98/95Mo of ca. − 0.21 ± 0.06‰ suggesting that the mantle may have maintained a similar Mo isotope composition throughout the post-Archean. The Mo isotope composition of the continental crust is currently the least well-constrained value of major geochemical reservoirs. A preliminary estimate available for maximum value for the upper continental crust yields a super-chondritic δ98/95Mo of ca. + 0.15‰. The value of the bulk continental crust remains unknown but is likely to be lower. Assuming a chondritic bulk silicate Earth differentiates solely into continental crust and depleted mantle reservoirs, the δ98/95Mo of the average continental crust would range between + 0.1 and + 0.35‰. This is broadly compatible with the initial observations, making Mo the first non-radiogenic isotopic system to show such an apparent complementarity between the continents and mantle reservoirs. Given that deep recycled crust is characterised by δ98/95Mo lower than that of depleted mantle, subduction provides a mechanism by which to affect this change
The multidisciplinary management of non-melanoma conchal bowl skin cancer
No full textMohs micrographic surgery (MMS) has been shown to achieve high cure rates and reduce recurrence rates of skin cancer in auricular and preauricular regions. Non-melanoma skin cancers of the conchal bowl are difficult to treat due to the challenge of accessing them and their close association with surrounding structures that may be inadvertently involved. Treatment goals in this anatomical area include total tumour removal and maximal tissue conservation to provide the best functional and aesthetic result for the patient. We present two patients with conchal bowl basal cell carcinoma treated with MMS and found to have extensive disease that benefited from collaborative management with an ear, nose and throat (ENT) surgeon. Where extensive subclinical spread is encountered or complex reconstruction is required it is useful to adopt a multidisciplinary approach to achieve total tumour control and maximal tissue conservation. Currently preoperative assessment of tumour margins is difficult and limited data are available on what cases should be co-managed. Our recommendation is that collaborative ENT involvement be reserved for cases where a long history is involved, a history of recurrence, previous failed excisions, close proximity to difficult to access areas, histological subtypes of skin carcinoma that are known to be aggressive or recurrent or when there is suspicion of subclinical spread based on other grounds
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