Off-resonance magnetisation transfer contrast (MTC) MRI using fast field-cycling (FFC)

Peer reviewedPostprin

Simple algorithm for the correction of MRI image artefacts due to random phase fluctuations

Grant support: This work was supported by EPSRC [grant numbers EP/E036775/1, EP/K020293/1] and received funding from the European Union's Horizon 2020 research and innovation programme [grant agreement No 668119, project “IDentIFY”]Peer reviewedPublisher PD

"Non-invasive" portable laser ablation sampling of art and archaeological materials with subsequent Sr-Nd isotope analysis by TIMS using 10¹³ Ω amplifiers

A new integrated trace element and multi-isotope provenancing methodology is presented that uses a portable “non-invasive” pulsed laser ablation sampling technique. Samples are collected on location onto Teflon filters for return to a clean laboratory for low blank (pg) geochemical procedures. Ablation pits approximately 60 or 120 μm in width and depth remove mg amounts of material. Following dissolution, trace element ratios are determined by inductively coupled plasma mass spectrometry and combined Sr–Nd isotopes by thermal ionization mass spectrometry. Use of 1013 Ω resistors allows precise analysis of subnanogram amounts of Sr-Nd isotopes, which coupled with the trace element data, provides highly effective multi-variant discrimination for material provenance and authenticity verification. Monitoring of blank contributions is required

Subslab mantle of African provenance infiltrating the Aegean mantle wedge

The presence of a tear in the subducting African slab has a strong effect on Neogene magmatism in western Turkey, but its influence on volcanism in the Quaternary Aegean arc to the west is unknown. In order to investigate to what extent arc volcanism can be affected by slab-parallel mantle flow from a slab window, we present new trace element and Nd-Pb isotope data for Nisyros and Santorini volcanoes. Trace element modeling allows quantification of the infiltration of trace element-enriched mantle of subslab provenance through the slab tear into the depleted Aegean mantle wedge. Primitive Nisyros magmas record melting of a mixed source that contains as much as 10% of the enriched, subslab mantle component, and a contribution of this component can be traced as far west as Santorini, ~250 km away from the slab tear. We conclude that trace element and Nd-Pb isotope variations between Nisyros and Santorini do not require along-arc variations in subducting sediment composition, but reflect the heterogeneous nature of the Aegean mantle wedge related to infiltration of subslab mantle through the slab tear. Our geochemical evidence is in excellent agreement with predictions made on the basis of mantle tomography and anisotropy that indicate toroidal mantle flow around the edge of the Aegean slab. This implies that suction related to slab rollback can lead to the infiltration of subslab mantle material and slab-parallel mantle flow, thus potentially strongly influencing arc volcanism, processes that perhaps need greater assessment in other arc systems

Seeking, accepting and declining help for emotional distress in cancer: A systematic review and thematic synthesis of qualitative evidence

Many individuals affected by cancer who experience emotional distress report not wanting help. This review aims to understand why individuals affected by cancer seek, accept or decline help for emotional distress and what influences these actions. A systematic review and thematic synthesis of the qualitative literature was conducted. Using pre-defined search terms, four electronic databases were searched from January 2000 to May 2016. Pre-determined inclusion and exclusion criteria were then applied. Identified papers were quality appraised. In total, 32 papers were included in the synthesis. Four themes emerged from data synthesis: attaining normality—the normality paradox; being emotionally literate; perceptions of help; needs-support gap. Attaining normality is ideographic, context dependent and temporally situated; some individuals maintain normality by not seeking/declining help whereas others seek/accept help to achieve a new normality. Thus, attaining normality paradoxically functions to explain both why individuals sought/accepted help or did not seek/declined help. Data indicate that a context dependent, systems thinking approach is merited to enhance psychosocial care. In particular, clinicians must actively explore the personal context of an individual's distress to ensure that help desired and help offered are mutually understood. Further research must address the limitations of the current evidence base to advance theoretical understanding

Sub-nanogram Pb isotope analysis of individual melt inclusions

Precise analysis of 20xPb/204Pb ratios is challenging when the amount of Pb is limited by sample volume or elemental concentration. The current precision impedes meaningful analyses of analytes with sub-nanogram Pb contents, such as individual melt inclusions with typical diameters (200 pg Pb, which will ultimately help to better constrain mantle heterogeneity beneath mid-ocean ridges, oceanic islands, and volcanic arcs

Archaean and Proterozoic diamond growth from contrasting styles of large-scale magmatism

Precise dating of diamond growth is required to understand the interior workings of the early Earth and the deep carbon cycle. Here we report Sm-Nd isotope data from 26 individual garnet inclusions from 26 harzburgitic diamonds from Venetia, South Africa. Garnet inclusions and host diamonds comprise two compositional suites formed under markedly different conditions and define two isochrons, one Archaean (2.95 Ga) and one Proterozoic (1.15 Ga). The Archaean diamond suite formed from relatively cool fluid-dominated metasomatism during rifting of the southern shelf of the Zimbabwe Craton. The 1.8 billion years younger Proterozoic diamond suite formed by melt-dominated metasomatism related to the 1.1 Ga Umkondo Large Igneous Province. The results demonstrate that resolving the time of diamond growth events requires dating of individual inclusions, and that there was a major change in the magmatic processes responsible for harzburgitic diamond formation beneath Venetia from the Archaean to the Proterozoic

Formation of unusual yellow Orapa diamonds

Twenty eclogitic diamonds from Orapa Mine (Botswana) with an unusual yellow colour are characterised for their growth structure, N systematics, and C isotope composition, and the major element composition of their silicate inclusions. The diamonds show complex luminescence with green, blue and non-luminescent zones and occasional sector zonation. All parts of the diamonds have low total N concentrations (<50 at.ppm, with one exception of <125 at.ppm) and a limited range in C isotope composition (−5.7 to −10.6‰). Fourier Transform Infrared spectra show bands at 1334, 1332, 1282, and 1240 cm−1 typical for Ib-IaA diamonds. Relict unaggregated N defects (Ns o and Ns +) are present and the preservation is likely caused by the low N concentrations and possible low mantle residence temperatures rather than young diamond formation (inclusion ages of 140, 1096, 1699 Ma; Timmerman et al. Earth Planet Sc Lett 463:178–188, 2017). Garnet and clinopyroxene inclusions extracted from 14 diamonds have an eclogitic composition with relatively low Ca contents and based on all characteristics, these diamonds form a distinct population from Orapa