Numerical modelling of multi-phase multi-component reactive transport in the Earth's interior

This is a pre-copyedited, author-produced PDF of an article accepted for publication in Geophysical journal international following peer review. The version of record Oliveira, B., Afonso, J., Zlotnik, S., Diez, P. Numerical modelling of multi-phase multi-component reactive transport in the Earth's interior. "Geophysical journal international", 1 Gener 2018, vol. 212, núm. 1, p. 345-388 is available online at: https://doi.org/10.1093/gji/ggx399.We present a conceptual and numerical approach to model processes in the Earth's interior that involve multiple phases that simultaneously interact thermally, mechanically and chemically. The approach is truly multiphase in the sense that each dynamic phase is explicitly modelled with an individual set of mass, momentum, energy and chemical mass balance equations coupled via interfacial interaction terms. It is also truly multi-component in the sense that the compositions of the system and its constituent thermodynamic phases are expressed by a full set of fundamental chemical components (e.g. SiO$_2$, Al$_2$O$_3$, MgO, etc) rather than proxies. In contrast to previous approaches these chemical components evolve, react with, and partition into, different phases with different physical properties according to an internally-consistent thermodynamic model. This enables a thermodynamically-consistent coupling of the governing set of balance equations. Interfacial processes such as surface tensions and/or surface energy contributions to the dynamics and energetics of the system are also taken into account. The model presented here describes the evolution of systems governed by Multi-Phase Multi-Component Reactive Transport (MPMCRT) based on Ensemble Averaging and Classical Irreversible Thermodynamics principles. This novel approach provides a flexible platform to study the dynamics and non-linear feedbacks occurring within various natural systems at different scales. This notably includes major-and trace-element transport, diffusion-controlled trace-element re-equilibration or rheological changes associated with melt generation and migration in the Earth's mantle.Peer ReviewedPostprint (author's final draft

The subductability of continental lithosphere: the before and after story

The temporal evolution of internal forces in a collision environment controls first-order characteristics such as convergence rate, slab dip, subduction stall, and slab breakoff, amongst others. Foremost among these forces are the positive buoyancy provided by the subduction of felsic continental material and the negative buoyancy associated with the slab. In this work we use fully dynamic thermomechanical models coupled with thermodynamic/petrological formalisms to study the evolution of these forces during a continent–arc/microcontinent collision and their influence on the large-scale dynamics of the system. Two distinctive features of our models that allow a self-consistent assessment of collision dynamics are: (1) the use of a new thermodynamic database valid up to ~25–30 GPa that includes most of the major phases relevant to continental subduction, and (2) a fully dynamic approach in which no velocities are imposed to either force or stop subduction. The former allows realistic computations of the buoyancy forces driving the system as a function of P-T-composition. The latter assures that computed velocities emerge self-consistently in our simulations in response to the balance between internal forces in our numerical domain. The main results from our experiments can be summarized as follows. (1) The delamination of the lithospheric mantle after a short episode of continental subduction is a viable scenario to end continental subduction; the associated evolution of convergence is comparable to those proposed for real collision setting. (2) We corroborate previous results showing that the main control on the dynamics and final configuration (type of slab breakoff) of the collision is the rheology and composition of the continental crust; strong mafic crusts favor deep subduction and recycling of significant volumes of continental material, while soft felsic crusts preclude them. (3) Subducted continental crust remains buoyant with respect to the surrounding mantle down to depths of ~250–300 km, thus allowing exhumation of deeply subducted crust as long as a detachment from the slab occurs. (4) Realistic compositional stratifications in the continental lithospheric mantle exert only a modest influence on the overall evolution of the collision system. (5) Subducted continental crust to depths >250–300 km becomes significantly denser than the surrounding mantle due to the appearance in the solid assemblage of high-density phases such as hollandite and stishovite; this provides extra negative buoyancy to the slab and precludes the exhumation of crustal components. This supports the idea of the existence of a “depth of no return” for continental material at around 250 km depth.Peer ReviewedPostprint (author's final draft

An efficient and general approach for implementing thermodynamic phase equilibria information in geophysical and geodynamic studies

We present a flexible, general, and efficient approach for implementing thermodynamic phase equilibria information (in the form of sets of physical parameters) into geophysical and geodynamic studies. The approach is based on Tensor Rank Decomposition methods, which transform the original multidimensional discrete information into a separated representation that contains significantly fewer terms, thus drastically reducing the amount of information to be stored in memory during a numerical simulation or geophysical inversion. Accordingly, the amount and resolution of the thermodynamic information that can be used in a simulation or inversion increases substantially. In addition, the method is independent of the actual software used to obtain the primary thermodynamic information, and therefore, it can be used in conjunction with any thermodynamic modeling program and/or database. Also, the errors associated with the decomposition procedure are readily controlled by the user, depending on her/his actual needs (e.g., preliminary runs versus full resolution runs). We illustrate the benefits, generality, and applicability of our approach with several examples of practical interest for both geodynamic modeling and geophysical inversion/modeling. Our results demonstrate that the proposed method is a competitive and attractive candidate for implementing thermodynamic constraints into a broad range of geophysical and geodynamic studies. MATLAB implementations of the method and examples are provided as supporting information and can be downloaded from the journal's website.Peer ReviewedPostprint (author's final draft

A reduced order approach for probabilistic inversions of 3-D magnetotelluric data I: general formulation

Simulation-based probabilistic inversions of 3-D magnetotelluric (MT) data are arguably the best option to deal with the nonlinearity and non-uniqueness of the MT problem. However, the computational cost associated with the modelling of 3-D MT data has so far precluded the community from adopting and/or pursuing full probabilistic inversions of large MT data sets. In this contribution, we present a novel and general inversion framework, driven by Markov Chain Monte Carlo (MCMC) algorithms, which combines (i) an efficient parallel-in-parallel structure to solve the 3-D forward problem, (ii) a reduced order technique to create fast and accurate surrogate models of the forward problem and (iii) adaptive strategies for both the MCMC algorithm and the surrogate model. In particular, and contrary to traditional implementations, the adaptation of the surrogate is integrated into the MCMC inversion. This circumvents the need of costly offline stages to build the surrogate and further increases the overall efficiency of the method. We demonstrate the feasibility and performance of our approach to invert for large-scale conductivity structures with two numerical examples using different parametrizations and dimensionalities. In both cases, we report staggering gains in computational efficiency compared to traditional MCMC implementations. Our method finally removes the main bottleneck of probabilistic inversions of 3-D MT data and opens up new opportunities for both stand-alone MT inversions and multi-observable joint inversions for the physical state of the Earth's interior.Fil: Manassero, María Constanza. Macquarie University; AustraliaFil: Afonso, Juan Carlos. Macquarie University; AustraliaFil: Zyserman, Fabio Ivan. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Departamento de Geofísica Aplicada; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Zlotnik, Sergio. Universidad Politécnica de Catalunya; EspañaFil: Fomin, I.. Macquarie University; Australi

A reduced order approach for probabilistic inversions of 3D magnetotelluric data II: joint inversion of MT and surface-wave data

Joint probabilistic inversions of magnetotelluric (MT) and seismic data have great potential for imaging the thermochemical structure of the lithosphere as well as mapping fluid/melt pathways and regions of mantle metasomatism. In this contribution, we present a novel probabilistic (Bayesian) joint inversion scheme for 3D MT and surface-wave dispersion data particularly designed for large-scale lithospheric studies. The approach makes use of a recently developed strategy for fast solutions of the 3D MT forward problem (Manassero et al., 2020, https://doi.org/10.1093/gji/ggaa415) and combines it with adaptive Markov chain Monte Carlo (MCMC) algorithms and parallel-in-parallel strategies to achieve extremely efficient simulations. To demonstrate the feasibility, benefits and performance of our joint inversion method for imaging the temperature and conductivity structures of the lithosphere, we apply it to two numerical examples of increasing complexity. The inversion approach presented here is timely and will be useful in the joint analysis of MT and surface wave data that are being collected in many parts of the world. This approach also opens up new avenues for the study of trans-lithospheric and trans-crustal magmatic systems, the detection of metasomatized mantle, and the incorporation of MT into multi-observable inversions for the physical state of the Earth's interior.We thank Farshad Salajegheh for providing part of his Matlab codes for plotting results 850 Special thanks to Kate Selway and Anandaroop Ray for their suggestions at different 851 stages of this work. The 3D rendering views were created using ParaView (Ahrens et al., 852 2005). 853 MCM thanks support from an International Macquarie Research Excellence Schol854 arship (iMQRES). MCM and JCA acknowledge support from ARC Grant DP160103502, 855 ARC Linkage Grant LP170100233, the ARC Centre of Excellence Core to Crust Fluids 856 Systems (http://www.ccfs.mq.edu.au) and the Centre for Earth Evolution and Dynam857 ics, Geoscience Australia and the European Space Agency via the “3D Earth - A Dy858 namic Living Planet”. FZ acknowledges support from CONICET through grant PIP 112- 859 201501-00192. SZ has been funded by the Spanish Ministry through grant DPI2017-85139- 860 C2-2-R, by Catalan government through grant 2017-SGR-1278 and by the EU’s Hori861 zon 2020 research and innovation programme under the Marie Sklodowska-Curie grant 862 agreement No 777778.Peer ReviewedPostprint (author's final draft

The Siderophore Piscibactin Is a Relevant Virulence Factor for Vibrio anguillarum Favored at Low Temperatures

Vibrio anguillarum causes vibriosis, a hemorrhagic septicaemia that affects many cultured marine fish species worldwide. Two catechol siderophores, vanchrobactin and anguibactin, were previously identified in this bacterium. While vanchrobactin is a chromosomally encoded system widespread in all pathogenic and environmental strains, anguibactin is a plasmid-encoded system restricted to serotype O1 strains. In this work, we have characterized, from a serotype O2 strain producing vanchrobactin, a novel genomic island containing a cluster of genes that would encode the synthesis of piscibactin, a siderophore firstly described in the fish pathogen Photobacterium damselae subsp. piscicida. The chemical characterization of this siderophore confirmed that some strains of V. anguillarum produce piscibactin. An in silico analysis of the available genomes showed that this genomic island is present in many of the highly pathogenic V. anguillarum strains lacking the anguibactin system. The construction of single and double biosynthetic mutants for vanchrobactin and piscibactin allowed us to study the contribution of each siderophore to iron uptake, cell fitness, and virulence. Although both siderophores are simultaneously produced, piscibactin constitute a key virulence factor to infect fish, while vanchrobactin seems to have a secondary role in virulence. In addition, a transcriptional analysis of the gene cluster encoding piscibactin in V. anguillarum showed that synthesis of this siderophore is favored at low temperatures, being the transcriptional activity of the biosynthetic genes three-times higher at 18°C than at 25°C. We also show that iron levels and temperature contribute to balance the synthesis of both siderophoresThis work was supported by grants AGL2015-63740-C2-1-R and AGL2015-63740-C2-2-R (AEI/FEDER, EU) from the State Agency for Research (AEI) of Spain, and co-funded by the FEDER Programme from the European Union. The support of Xunta de Galicia (Spain) with grant GRC-2014/007 is also acknowledgedS

Towards An ”ecology Of Lore And Knowledge” in Health: An Invitation From The Terreiros To Dialogue

A partir da análise de um conjunto de entrevistas com lideranças de comunidades de terreiro, este artigo discute as possibilidades de uma “ecologia de saberes” em saúde e, mais concretamente, as possibilidades de interação entre os saberes de matriz africana e os saberes da medicina científica ocidental. Nesse percurso, estabelecendo um diálogo entre a “imaginação conceitual” dos autores e aquela de seus interlocutores de matriz africana, explora os possíveis desfechos de um processo “ecologizador” entre aqueles dois tipos de saber, seus pressupostos e as barreiras para sua efetivação. Nesse sentido, no lugar de uma aproximação teórica unilateral ao tema, o artigo busca visibilizar e valorizar a elaboração conceitual das mães e dos pais de santo entrevistados, construindo seu argumento a partir de um esforço imaginativo transcultural

The history of mechanical ventilation

The aim of mechanical ventilation is to substitute physiological respiratory function. The boom of mechanical ventilation came during the XVIII century with the development of Reanimation Societies in Europe, who promoted the use of positive pressure ventilation modes. This type of ventilation caused new complications due to excessive positive pressure in the airway. Therefore, during the XIX century negative pressure ventilation predominated, which became essential during the second half of the 19th century and first half of the 20th century. Positive pressure ventilation was relegated to operating rooms until 1952, when it was imposed over negative pressure ventilation during the Copenhagen polio epidemic. Björn Ibsen contributed significantly to this change of ventilation paradigm, which led to the latest ventilation strategies and the development of the actual intensive care units

Religion and health: to transform absence in presence

O artigo analisa percepções de profissionais de uma unidade básica de saúde a respeito das relações entre religião e saúde para apreender como os modos de considerar a religião nas práticas de saúde podem produzir equidades ou iniquidades. Trata-se de um estudo exploratório de abordagem qualitativa desenvolvido a partir de entrevistas estruturadas individuais, analisadas com o intuito de detectar práticas de sentido relevantes para a discussão de equidade em saúde. Os resultados destacam: uma concepção negativa da influência da religião dos usuários sobre os cuidados e as agências interessadas na redução dessa interferência da religião; as dificuldades e desconfortos relacionados ao modo de o profissional lidar com a própria religião no exercício do cuidado e na relação interprofissional; que o Sistema Único de Saúde não considera a dimensão religiosa, fazendo-se necessárias políticas públicas específicas ou transformações culturais profundas; e a falta de conhecimento de características das religiões afrobrasileiras que demandem cuidados específicos. Tais resultados sugerem que a negligência em relação à questão religiosa mantém oculta uma prática proativa de apagamento das diferenças, conduzindo a uma reflexão sobre o que, em se tratando de equidades e iniquidades, tem produzido a epistème moderna no âmbito das práticas instituídas na atenção básica.T h e a r t i c l e a n a l y z e s t h e p e r c e p t i o n s o f professionals of a basic health unit regarding the relationship between religion and health in order to apprehend how the ways of considering religion in health practices can produce equities or iniquities. It is an exploratory study of qualitative approach developed from individual structured interviews, analyzed with the intention of detecting signification practices relevant to the discussion of equity in health. The results highlight: a negative conception of the influence of the user’s religion on care and agency interested in reducing this interference of religion; the difficulties and discomforts related to the way the professional deals with their own religion in the exercise of care and in the interprofessional relationship; that the Brazilian National Health System does not consider the religious dimension, creating the need for specific public policies or deep cultural transformations; and the lack of knowledge of the characteristics of Afro-Brazilian religions that demand specific care. These results suggest that negligence of the religious question conceals a proactive practice of erasing differences, which leads to a reflection on what, in the case of equities and iniquities, has produced the modern epistème within the framework of the practices instituted in the Primary Health Care

Urban ruins: scenarios for the in-between, Guimarães, Portugal

PTDC/ATP-EUR/1180/201