Variationally Constrained Numerical Solution of Electrical Impedance Tomography

We propose a novel, variational inversion methodology for the electrical impedance tomography problem, where we seek electrical conductivity σ inside a bounded, simply connected domain Ω, given simultaneous measurements of electric currents I and potentials V at the boundary. Explicitly, we make use of natural, variational constraints on the space of admissible functions σ, to obtain efficient reconstruction methods which make best use of the data. We give a detailed analysis of the variational constraints, we propose a variety of reconstruction algorithms and we discuss their advantages and disadvantages. We also assess the performance of our algorithms through numerical simulations and comparisons with other, well established, numerical reconstruction methods

Staying with the trouble of networks

Networks have risen to prominence as intellectual technologies and graphical representations, not only in science, but also in journalism, activism, policy, and online visual cultures. Inspired by approaches taking trouble as occasion to (re)consider and reflect on otherwise implicit knowledge practices, in this article we explore how problems with network practices can be taken as invitations to attend to the diverse settings and situations in which network graphs and maps are created and used in society. In doing so, we draw on cases from our research, engagement and teaching activities involving making networks, making sense of networks, making networks public, and making network tools. As a contribution to “critical data practice,” we conclude with some approaches for slowing down and caring for network practices and their associated troubles to elicit a richer picture of what is involved in making networks work as well as reconsidering their role in collective forms of inquiry.</p

Visual Network Exploration for Data Journalists

International audienceNetworks are classic but under-acknowledged figures of journalistic storytelling. Who is connected to whom and by which means? Which organizations receive support from which others? What resources or information circulate through which channels and which intermediaries enable and regulate their flows? These are all customary stories and lines of inquiry in journalism and they all have to do with networks. Additionally, the recent spread of digital media has increasingly confronted journalists with information coming not only in the traditional form of statistic tables, but also of relational databases. Yet, journalists have so far made little use of the analytical resources offered by networks. To address this problem in this chapter we examine how " visual network exploration " may be brought to bear in the context of data journalism in order to explore, narrate and make sense of large and complex relational datasets. We borrow the more familiar vocabulary of geographical maps to show how key graphical variables such as position, size and hue can be used to interpret and characterise graph structures and properties. We illustrate this technique by taking as a starting point a recent example from journalism, namely a catalogue of French information sources compiled by Le Monde's The Decodex. We establish that good visual exploration of networks is an iterative process where practices to demarcate categories and territories are entangled and mutually constitutive. To enrich investigation we suggest ways in which the insights of the visual exploration of networks can be supplemented with simple calculations and statistics of distributions of nodes and links across the network. We conclude with reflection on the knowledge-making capacities of this technique and how these compare to the insights and instruments that journalists have used in the Decodex project – suggesting that visual network exploration is a fertile area for further exploration and collaborations between data journalists and digital researchers

Heredabilidad de la resistencia a la roya común (Puccinia melanocephala H. et P. Sydow) en familias FS de caña de azúcar (Saccharum spp)

La caña de azúcar es una especie cultivada de gran complejidad genética. Se postula que la resistencia a la roya común (Puccinia melanocephala H. et P. Sydow) tendría base oligénica u oligogénica con efectos principalmente aditivos y de interacción génica. El empleo de variedades resistentes es el método de control más eficaz, por lo que resulta importante investigar el mecanismo genético que determina la expresión de este atributo. La finalidad de este trabajo fue estimar en poblaciones híbridas la heredabilidad de la resistencia a la roya común, como la regresión de las medias de las progenies sobre las medias de los padres. En la localidad de Barro Negro (Ingenio Río Grande, Jujuy) se investigaron durante tres años consecutivos ocho familias FS BIP (biparentales), involucrando 11 progenitores con diferentes expresiones de resistencia a la enfermedad. La regresión conjunta a través de años permitió estimar una h2= 0,66 (determinación 48%), con valores de 0,90, 0,85 y 0,33 para los años 1, 2 y 3, respectivamente. Las diferencias entre años se explican por la variabilidad de componentes ambientales y probablemente por las cambiantes estructuras poblacionales de P. melanocephala. Los resultados indican la predominancia de efectos genéticos aditivos en la determinación de la resistencia, que explicarían un 92% de la varianza genética total. La heredabilidad es un buen indicador del potencial de los padres para transmitir resistencia a las progenies, lo que permite orientar la selección de combinaciones híbridas que incrementen la frecuencia de aparición de recombinaciones resistentes. Los resultados indican una naturaleza poligénica en la determinación de la resistencia a la roya común en los materiales investigados. Este tipo de resistencia podría complementarse con otros mecanismos de resistencia mediados por genes mayores, contribuyendo a la sostenibilidad de la resistencia.The genetics of cultivated sugar cane as crop is complex. Resistance to common rust (Puccinia melanocephala H. et P. Sydow) seems to have a poligenic or oligonenic genetic basis, showing mainly additive and interaction genetic effects. The use of resistant varietiies is accepted to be the best suited method for its control, which justifies research on acting genetic mechanisms. The aim of the research was to estimate heritability of resistance to common rust by means of the regression of hybrid progenies means on parents resistance means. Eight hybrid FS families (BIP) involving 11 parents with different degrees of resistance were investigated for three consecutive years at Barro Negro (Rio Grande Factory, Jujuy, Argentina). Joint regression across years estimated heritability as h2= 0.66 (determination 48%) with values of 0.90, 0.85 and 0.33 for years 1, 2 and 3, respectively. Differences among years are explained by variation of environmental components and probably also due to variation in the population genetic structure of P. melanocephala. Results indicate the predominance of additive genetic effects determining resistance, which explain 92% of total genetic variation. Heritability indicates the potential of parents to transmit resistance to their progenies, enabling the selection of appropiate hybrid combinations for increasing the frequency of resistant progenies. Results strongly indicate a polygenic nature of the genetic determination of common rust resistance in these materials. This type of resistance could be complemented with other reported mechanisms contributing to sustain the resistance.Gerencia de Comunicación e Imagen InstitucionalFil: Simon, Graciela Elisa. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias. Cátedra de Mejoramiento Genético; ArgentinaFil: Collavino, Norma Graciela. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Cátedra de Mejoramiento Genético Vegetal; ArgentinaFil: Gray, Liliana Norma. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias. Cátedra de Mejoramiento Vegetal; ArgentinaFil: Mariotti, Jorge. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Cátedra de Mejoramiento Genético Vegetal; Argentin

Testing and not testing for coronavirus on Twitter : surfacing testing situations across scales with interpretative methods

How was testing—and not testing—for coronavirus articulated as a testing situation on social media in the Spring of 2020? Our study examines everyday situations of Covid-19 testing by analyzing a large corpus of Twitter data collected during the first 2 months of the pandemic. Adopting a sociological definition of testing situations, as moments in which it is no longer possible to go on in the usual way, we show how social media analysis can be used to surface a range of such situations across scales, from the individual to the societal. Practicing a form of large-scale data exploration we call “interpretative querying” within the framework of situational analysis, we delineated two types of coronavirus testing situations: those involving locations of testing and those involving relations. Using lexicon analysis and composite image analysis, we then determined what composes the two types of testing situations on Twitter during the relevant period. Our analysis shows that contrary to the focus on individual responsibility in UK government discourse on Covid-19 testing, English-language Twitter reporting on coronavirus testing at the time thematized collective relations. By a variety of means, including in-memoriam portraits and infographics, this discourse rendered explicit challenges to societal relations and arrangements arising from situations of testing and not testing for Covid-19 and highlighted the multifaceted ways in which situations of corona testing amplified asymmetrical distributions of harms and benefits between different social groupings, and between citizens and state, during the first months of the pandemic

Children\u27s Health in Latin America: The Influence of Environmental Exposures

Background:Chronic diseases are increasing among children in Latin America. Objective and Methods:To examine environmental risk factors for chronic disease in LatinAmerican children and to develop a strategic initiative for control of these exposures, the WorldHealth Organization (WHO) including the Pan American Health Organization (PAHO), the Collegium Ramazzini, and Latin American scientists reviewed regional and relevant global data. Findings: Industrial development and urbanization are proceeding rapidly in Latin America and environmental pollution has become widespread. Environmental threats to children\u27s health include traditional hazards such as indoor air pollution and drinking water contamination; as well as the newer hazards of urban air pollution; toxic chemicals such as lead, asbestos, mercury,arsenic, and pesticides;hazardous and electronic waste;and climate change. The mix of traditional and modern hazards varies greatly across and within countries reflecting industrialization, urbanization and socioeconomic forces. Conclusions: To control environmental threats to children\u27s health in Latin America, WHO, including PAHO will focus on the most highly prevalent and serious hazards - indoor and outdoor air pollution, water pollution, and toxic chemicals. Strategies for controlling these hazards include developing tracking data on regional trends in children\u27s environmental health(CEH); building a network of Collaborating Centres; promoting biomedical research in CEH;building regional capacity; supporting development of evidence-based prevention policies; studying the economic costs of chronic diseases in children; and developing platforms for dialogue with relevant stakeholders.

Face perception enhances insula and motor network reactivity in Tourette syndrome

Tourette syndrome is a neurodevelopmental disorder, characterised by motor and phonic tics. Tics are typically experienced as avolitional, compulsive, and associated with premonitory urges. They are exacerbated by stress and can be triggered by external stimuli, including social cues like the actions and facial expressions of others. Importantly, emotional social stimuli, with angry facial stimuli potentially the most potent social threat cue, also trigger behavioural reactions in healthy individuals, suggesting that such mechanisms may be particularly sensitive in people with Tourette syndrome. Twenty-one participants with Tourette syndrome and 21 healthy controls underwent functional magnetic resonance imaging while viewing faces wearing either neutral or angry expressions to quantify group differences in neural activity associated with processing social information. Simultaneous video recordings of participants during neuroimaging enabled us to model confounding effects of tics on task-related responses to the processing of faces. In both Tourette syndrome and control participants, face stimuli evoked enhanced activation within canonical face perception regions, including the occipital face area and fusiform face area. However, the Tourette syndrome group showed additional responses within the anterior insula to both neutral and angry faces. Functional connectivity during face viewing was then examined in a series of psychophysiological interactions. In Tourette syndrome participants, the insula showed functional connectivity with a set of cortical regions previously implicated in tic generation: the pre-supplementary motor area, premotor cortex, primary motor cortex, and the putamen. Furthermore, insula functional connectivity with the globus pallidus and thalamus varied in proportion to tic severity, while supplementary motor area connectivity varied in proportion to premonitory sensations, with insula connectivity to these regions increasing to a greater extent in patients with worse symptom severity. In addition, the occipital face area showed increased functional connectivity in Tourette syndrome participants with posterior cortical regions, including primary somatosensory cortex, and occipital face area connectivity with primary somatosensory and primary motor cortices varied in proportion to tic severity. There were no significant psychophysiological interactions in controls. These findings highlight a potential mechanism in Tourette syndrome through which heightened representation within insular cortex of embodied affective social information may impact the reactivity of subcortical motor pathways, supporting programmed motor actions that are causally implicated in tic generation. Medicinal and psychological therapies that focus on reducing insular hyper-reactivity to social stimuli may have potential benefit for tic reduction in people with Tourette syndrome