Which effective viscosity?

Magmas undergoing shear are prime examples of flows that involve the transport of solids and gases by a separate (silicate melt) carrier phase. Such flows are called multiphase, and have attracted much attention due to their important range of engineering applications. Where the volume fraction of the dispersed phase (crystals) is large, the influence of particles on the fluid motion becomes significant and must be taken into account in any explanation of the bulk behaviour of the mixture. For congested magma deforming well in excess of the dilute limit (particle concentrations >40% by volume), sudden changes in the effective or relative viscosity can be expected. The picture is complicated further by the fact that the melt phase is temperature- and shear-rate-dependent. In the absence of a constitutive law for the flow of congested magma under an applied force, it is far from clear which of the many hundreds of empirical formulae devised to predict the rheology of suspensions as the particle fraction increases with time are best suited. Some of the more commonly used expressions in geology and engineering are reviewed with an aim to home in on those variables key to an improved understanding of magma rheology. These include a temperature, compositional and shear-rate dependency of viscosity of the melt phase with the shear-rate dependency of the crystal (particle) packing arrangement. Building on previous formulations, a new expression for the effective (relative) viscosity of magma is proposed that gives users the option to define a packing fraction range as a function of shear stress. Comparison is drawn between processes (segregation, clustering, jamming), common in industrial slurries, and structures seen preserved in igneous rocks. An equivalence is made such that congested magma, viewed in purely mechanical terms as a high-temperature slurry, is an inherently non-equilibrium material where flow at large Péclet numbers may result in shear thinning and spontaneous development of layering

Fenites associated with carbonatite complexes : a review

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Carbonatites and alkaline-silicate rocks are the most important sources of rare earth elements (REE) and niobium (Nb), both of which are metals imperative to technological advancement and associated with high risks of supply interruption. Cooling and crystallizing carbonatitic and alkaline melts expel multiple pulses of alkali-rich aqueous fluids which metasomatize the surrounding country rocks, forming fenites during a process called fenitization. These alkalis and volatiles are original constituents of the magma that are not recorded in the carbonatite rock, and therefore fenites should not be dismissed during the description of a carbonatite system. This paper reviews the existing literature, focusing on 17 worldwide carbonatite complexes whose attributes are used to discuss the main features and processes of fenitization. Although many attempts have been made in the literature to categorize and name fenites, it is recommended that the IUGS metamorphic nomenclature be used to describe predominant mineralogy and textures. Complexing anions greatly enhance the solubility of REE and Nb in these fenitizing fluids, mobilizing them into the surrounding country rock, and precipitating REE- and Nb-enriched micro-mineral assemblages. As such, fenites have significant potential to be used as an exploration tool to find mineralized intrusions in a similar way alteration patterns are used in other ore systems, such as porphyry copper deposits. Strong trends have been identified between the presence of more complex veining textures, mineralogy and brecciation in fenites with intermediate stage Nb-enriched and later stage REE enriched magmas. However, compiling this evidence has also highlighted large gaps in the literature relating to fenitization. These need to be addressed before fenite can be used as a comprehensive and effective exploration tool.This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 689909

Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020

We show the distribution of SARS-CoV-2 genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three available genomic nomenclature systems for SARS-CoV-2 to all sequence data from the WHO European Region available during the COVID-19 pandemic until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation. We provide a comparison of the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2.Peer reviewe

Numerical methods for stress analysis using known elasticity solutions

SIGLELD:D47900/83 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Endothelial dysfunction as a determinant of trastuzumab-mediated cardiotoxicity in patients with breast cancer

BACKGROUND: Breast cancer is the most common cancer in females in the UK and has greater severity in patients who overexpress human epidermal growth receptor 2 (HER2) proteins in the breast tissue. Trastuzumab is a humanised monoclonal antibody and is targeted towards blocking the HER2 pathway and effectively reduces the recurrence of breast cancer and associated mortality. However, trastuzumab is also associated with an increased risk of cardiotoxicity which likely results from inhibition of the HER2 pathway. Under normal conditions HER2 pathways help maintain the integrity of the myocardial contractile elements, as well as the coronary vasculature, but trastuzumab inhibits these survival pathways and increases the risk for congestive heart failure (CHF). In the present review, we summarise the pathways that are implicated in the development of CHF in patients receiving trastuzumab. We also highlight the role of trastuzumab-mediated endothelial dysfunction and CHF

Opiine Parasitoids (Hymenoptera: Braconidae) of Tropical Fruit Flies (Diptera: Tephritidae) of the Australian and South Pacific Region

Opiine wasps are well known larval and egg-larval parasitoids of dacine fruit flies, one of the most important insect pest groups of the South Pacific. For Australia, Papua New Guinea and other South Pacific island countries and territories, no regional synopsis is available for the opiines attacking fruit flies, despite their use in classical, inundative and manipulative biological control. We present a taxonomic synopsis and distribution and host records (44% of which are new) for each of the 15 species of dacine-parasitising opiine braconids found in the South Pacific. Species dealt with are Diachasmimorpha hageni (Fullaway), D. kraussii (Fullaway), D. longicaudata (Ashmead), D. tryoni (Cameron), Fopius arisanus (Sonan), F. deeralensis (Fullaway), F. ferrari Carmichael & Wharton, sp. n., F. illusorius (Fischer) , comb. n., F. schlingeri Wharton, Opius froggatti Fullaway, Psyttalia fijiensis (Fullaway), P. muesebecki (Fischer), P. novaguineensis (Szépligeti) and Utetes perkinsi (Fullaway). A potentially undescribed species, which may be a colour morph of F. vandenboschi (Fullaway), is diagnosed but not formally described. Fopius vandenboschi sensu stricto, Diachasmimorpha fullawayi Silvestri, Psyttalia concolor Szépligeti and P. incisi Silvestri have been liberated into the region but are not considered to have established: a brief diagnosis of each is included in event that undetected, low level populations do occur and are sampled. Biosteres illusorius Fischer is formally transferred to the genus Fopius. A single opiine specimen reared from a species of Bactrocera (Bulladacus) appears to be Utetes albimanus (Szépligeti), but damage to this specimen and to the holotype (the only previously known specimen) means that we can not confirm this species as a fruit fly parasite: a diagnosis of U. cf. albimanus is provided. Psyttalia novaguineensis could not be adequately separated from P. fijiensis using previously published characterisations and further work to resolve this complex is recommended. A key is provided to all taxa reared from fruit-infesting tephritids in the South Pacific region