Origin of basalts by hybridization in andesite-dominated arcs

Mafic magmas are common in subduction zone settings, yet their high density restricts their ascent to the surface. Once stalled in the crust, these magmas may differentiate, assimilate crust and other melts and mushes to produce hybridised intermediate magmas. The Soufriere Hills Volcano on Montserrat is a ‘type locality’ for these hybridisation processes and yet, just 3 km south of the crater, voluminous basalts have erupted from the South Soufriere Hills volcano within the same time period as the Soufriere Hills Volcano was erupting hybrid andesites (131 - 128 ka). Basaltic South Soufriere Hills magmas have 48 - 53 32 wt% SiO2 and 4 - 6 wt% MgO. They were hot (970 - 1160 °C), volatile-rich (melt inclusions contain up to 6.2 wt% H2O) and were stored at 8 – 13 km prior to eruption (based on olivine and pyroxene-hosted melt inclusion volatile geochemistry). Melt inclusions do not preserve basaltic liquids: they are andesitic to rhyolitic in composition, related to one another by a line of descent controlled by simple closed-system fractionation. Whole rock compositions, however, are best described by a hybridisation model involving “back”-mixing of andesitic to rhyolitic melts with mafic crystal phases such as magnetite, olivine, orthopyroxene and clinopyroxene. Phenocryst zoning illustrates repeated mixing events between evolved melts and mafic phenocrysts, which, when coupled with the heterogeneity of crystal compositions, strongly suggests that although the bulk composition is basalt (containing Fo80 olivine), they were assembled from disparate ingredients, likely derived from mafic crystal mushes and more evolved melt lenses of variable composition. The mixing events occur days to weeks prior to eruption. We propose that the South Soufriere Hills basaltic magmas, with their higher bulk density over andesites from neighbouring volcanoes, ultimately may have been eruptible owing to both the transtensional tectonics imposed by offshore grabens (related to the oblique subduction of the Lesser Antilles) and to surface unloading caused by large scale edifice collapse. Our observations support the idea that compositional changes in arcs might reflect not only changes in source compositions, but also effects caused by patterns in crustal strain and tectonics.MC and SFLW thank NERC for financial support via grant NE/K000403/1.This is the accepted manuscript. The final version is available from OUP at http://dx.doi.org/10.1093/petrology/egv00

The thermal regime around buried submarine high voltage cables

The expansion of offshore renewable energy infrastructure and the need for trans-continental shelf power transmission require the use of submarine High Voltage (HV) cables. These cables have maximum operating surface temperatures of up to 70°C and are typically buried 1–2 m beneath the seabed, within the wide range of substrates found on the continental shelf. However, the heat flow pattern and potential effects on the sedimentary environments around such anomalously high heat sources in the near surface sediments are poorly understood. We present temperature measurements from a 2D laboratory experiment representing a buried submarine HV cable, and identify the thermal regimes generated within typical unconsolidated shelf sediments—coarse silt, fine sand and very coarse sand. We used a large (2 × 2.5 m) tank filled with water-saturated spherical glass beads (ballotini) and instrumented with a buried heat source and 120 thermocouples, to measure the time-dependent 2D temperature distributions. The observed and corresponding Finite Element Method (FEM) simulations of the steady state heat flow regimes, and normalised radial temperature distributions were assessed. Our results show that the heat transfer and thus temperature fields generated from submarine HV cables buried within a range of sediments are highly variable. Coarse silts are shown to be purely conductive, producing temperature increases of >10°C up to 40 cm from the source of 60°C above ambient; fine sands demonstrate a transition from conductive to convective heat transfer between c. 20°C and 36°C above ambient, with >10°C heat increases occurring over a metre from the source of 55°C above ambient; and very coarse sands exhibit dominantly convective heat transfer even at very low (c. 7°C) operating temperatures and reaching temperatures of up to 18°C above ambient at a metre from the source at surface temperatures of only 18°C. These findings are important for the surrounding near surface environments experiencing such high temperatures and may have significant implications for chemical and physical processes operating at the grain and sub-grain scale; biological activity at both micro-faunal and macro-faunal levels; and indeed the operational performance of the cables themselves, as convective heat transport would increase cable current ratings, something neglected in existing standards

Blood Pressure Management Education

The expansion of telehealth with COVID-19 and recent recommendations to use at-home blood pressure monitoring to diagnose and monitor hypertension have increased the need for materials and education for clinicians and patients. A pilot project in Primary Care Internal Medicine UVM in Essex, VT, produced an electronic medical record dot phrase and compiled educational materials to initiate nurse visits for at-home BP measurements. Materials and experience with this pilot was researched for initiation of a similar program at UVM Family Medicine Hinesburg.https://scholarworks.uvm.edu/fmclerk/1674/thumbnail.jp

PARTICLE SEGREGATION IN TAPERED FLUIDIZED BEDS

In practical situations, a bed of particles often has a wide range of sizes or is a mixture of differently sized components, and this allows a number of different segregation structures to form depending on local flow conditions. These vary systematically in tapered beds. This paper is an experimental investigation of the interaction between size segregation and the effects on local flows in a tapered bed

Aquadi-u-chloro-bis(diethylenetriamine)dicopper(11) dichloride: A redetermination at 180 K

The structure of the title compound, [Cu2Cl2(C4H13N3)2(H2O)]Cl2, at 180 K is described in space group P21/n with a unit-cell volume twice that reported previously for the structure at 293 K [Willett (2001[Willett, R. D. (2001). Acta Cryst. E57, m605-m606.]). Acta Cryst. E57, m605-m606]. In the smaller unit cell, in space group P21/m, the complex has imposed mirror symmetry and unusually elongated displacement ellipsoids. At 180 K, refinement in the larger unit cell with no imposed symmetry resolves this issue. With room-temperature data collected from the same crystal, however, refinement using the larger unit cell gives no significant improvement, and the previously reported structure is considered to be most appropriate

Investigation into Early growth response 1 in colorectal disease: a study of EGR1 expression in colorectal tissue and novel protein interactions in cancer cells

Introduction: Early growth response 1 (EGR1) is a zinc-finger transcription factor involved in the regulation of cell growth. It can act as either a tumour suppressor or a tumour promoter with a role in the induction of apoptosis in cancer cells by various pathways and is likely to play a role in colorectal cancer (CRC). EGR1 also appears to play a significant role in inflammatory pathways, therefore a possible role in Inflammatory Bowel Disease (IBD) is hypothesised. Patients with IBD have a greater risk of developing CRC, which is increased with duration of symptoms and severity of inflammation and dysplasia. The aim of this study is to determine whether EGR1 is differentially expressed in diseased colon tissue and to investigate novel EGR1-protein interactions in CRC cell lines. Methods: The relative EGR1 expression in CRC cell lines and in normal mucosa and tumours of colorectal cancer patients was determined by qRT-PCR. IBD patient samples were also examined for differential EGR1 expression levels by qRT-PCR, before and after stimulation with inflammatory mediators. Statistical analysis of the data was performed using ‘R’ statistical package, with the mixed-model ANOVA. Statistical significance was set at < 0.05. The genotype of three EGR1 variants was determined in the samples using PCR and sequencing, and the methylation status of regions of the EGR1 promoter was determined using bisulfite sequencing. A yeasttwo hybrid screen was conducted with EGR1 as bait, and screened against a SW480 CRC cell line library. Interesting novel interactions were investigated using immunocytochemistry and immunoprecipitation, as was the novel interaction between EGR1 and NOD2 and between EGR1 and components of the cytoskeleton. Results: Investigation into the relative EGR1 mRNA expression in CRC has shown that there is differential expression of EGR1 between matched normal mucosa and tumour. EGR1 expression is decreased in IBD patients compared with healthy controls. Induction of EGR1 by inflammatory stimuli also appears to be aberrant in these patients. The differential expression of EGR1 was not associated with aberrant methylation of a large region of the EGR1 promoter in either the CRC or IBD patients or with the genotype of EGR1 variants. EGR1 localises to both the cytoplasm and the nucleus in CRC cell lines and this study demonstrate interactions with the IBD susceptibility protein NOD2 and with components of the cyotskeleton. A yeast-two hybrid screen conducted with EGR1 as bait using a CRC cell line library has identified several other novel protein interactions of EGR1 in CRC cell lines. Conclusion: EGR1 is differentially expressed in both CRC and IBD, and in the case of IBD shows aberrant activity, suggesting that EGR1 may play a role in both colorectal diseases. EGR1 interacts with the IBD protein NOD2, and components of the cytoskeleton in CRC cells. Several novel protein interactions with EGR1 have been identified and warrant further study