Expectation Propagation for Nonlinear Inverse Problems -- with an Application to Electrical Impedance Tomography

In this paper, we study a fast approximate inference method based on expectation propagation for exploring the posterior probability distribution arising from the Bayesian formulation of nonlinear inverse problems. It is capable of efficiently delivering reliable estimates of the posterior mean and covariance, thereby providing an inverse solution together with quantified uncertainties. Some theoretical properties of the iterative algorithm are discussed, and the efficient implementation for an important class of problems of projection type is described. The method is illustrated with one typical nonlinear inverse problem, electrical impedance tomography with complete electrode model, under sparsity constraints. Numerical results for real experimental data are presented, and compared with that by Markov chain Monte Carlo. The results indicate that the method is accurate and computationally very efficient.Comment: Journal of Computational Physics, to appea

An Analysis of Finite Element Approximation in Electrical Impedance Tomography

We present a finite element analysis of electrical impedance tomography for reconstructing the conductivity distribution from electrode voltage measurements by means of Tikhonov regularization. Two popular choices of the penalty term, i.e., $H^1(\Omega)$-norm smoothness penalty and total variation seminorm penalty, are considered. A piecewise linear finite element method is employed for discretizing the forward model, i.e., the complete electrode model, the conductivity, and the penalty functional. The convergence of the finite element approximations for the Tikhonov model on both polyhedral and smooth curved domains is established. This provides rigorous justifications for the ad hoc discretization procedures in the literature.Comment: 20 page

A história das Relações Internacionais dos BRICS (2009-2019): discursos, inovação e sensibilidades

The article discuss the main historical movements on BRICS international relations between 2009-2019: the emergence of narratives about success and failure of the BRICS; the capability of BRICS to promote innovations in the global order, and the responsiveness of BRICS to an array of themes on the umbrella of the concept of cooperation under sensitivity. New productive dialogue niches (health, security, development) in BRICS international relations has created circumstances of sensitive interactions between the countries, causing controversy and diplomatic edges that affected bilateral and multilateral ties between BRICS countries. Methodologically, it draws from multiple approaches that combine Qualitative Content Analysis (QCA), Foreign Policy Analysis (FPA), Critical Thinking and a historical international relations perspective, based on an empirically strong foundation on primary and secondary sources – including news, authorities discourse and official telegrams of Itamaraty and the more recent scientific studies on BRICS.O artigo discute os principais movimentos históricos das relações internacionais do BRICS entre 2009 e 2019: o surgimento de narrativas sobre o sucesso e o fracasso do BRICS; a capacidade do BRICS de promover inovações na ordem global e a capacidade de resposta do BRICS a uma variedade de temas, o que reflete-se no conceito de “cooperação sob sensibilidade”. Novos nichos de diálogo produtivo (saúde, segurança, desenvolvimento) nas relações internacionais do BRICS criaram circunstâncias de interações sensíveis entreos países, causando controvérsia e rusgas diplomáticas que afetaram os laços bilaterais e multilaterais entre os países do BRICS. Metodologicamente, ele se baseia em múltiplas abordagens que combinam Análise Qualitativa de Conteúdo (QCA), Análise de Política Externa (APF), Pensamento Crítico e uma perspectivahistórica de relações internacionais, com base em forte empiria e uso de fontes primárias e secundárias - incluindo notícias, discurso das autoridades e telegramas oficiais do Itamaraty e os estudos científicos mais recentes sobre o BRICS

The role of histone H3.3 lysine 4 and lysine 36 residues in mouse embryonic stem cells and neuronal development

Numerous mutations in histone H3 lysine 4 (H3K4) and H3 lysine 36 (H3K36) modifying enzymes have been reported in human disease, yet the role of the H3K4 and H3K36 residues in mammals remain unclear due to the clustered arrays of many histone genes. Replication-dependent canonical H3 (H3.1/H3.2) exists as multiple gene copies and supplies nucleosomes for packaging of newly synthesized DNA during replication. The histone variant H3.3 differs from canonical H3 by only 4 to 5 amino acids, which allow nucleosome assembly independent of DNA replication throughout the cell cycle and in post-mitotic cells. In this study, I set out to investigate the role of the K4 and K36 residues in the histone H3.3 variant, which is enriched at active regions of the mammalian genome and encoded by two isolated genes; therefore amenable to functional analysis. Using CRISPR-Cas9, I mutated the K4 or K36 residue of endogenous H3.3 to unmodifable alanine (A) in mouse embryonic stem cells (ESCs) and revealed that the K4A mutation, but not K36A, resulted in widespread gene expression changes and impairment of neuronal differentiation into glutamatergic neurons. Furthermore, K4A resulted in significant H3.3 protein depletion at transcription start sites and active enhancers of ESCs - without effects at other sites. Genomic regions depleted of H3.3K4A showed concerted alterations of histone modifications (decreased K27 acetylation and increased K4 methylation) regardless of gene expression changes. In differentiated neurons, the K4A mutation impacted protein stability and resulted in widespread proteasomal degradation of the mutant histone. Thus, H3.3K4 is required for site-specific nucleosome maintenance at regulatory regions, histone stability and cellular differentiation of ESCs. H3.3K36 is not required for H3.3 deposition and turnover inside coding regions, and the K36A mutation affected gene expression at later stages of neurodevelopment. Furthermore, the K36A mutation globally depleted H3K36 di-metylation levels in ESCs, which resulted in a spread of the repressive mark H3K27me3, suggesting that H3K36 di-methylation is required to restrict the activity of PRC2. This study demonstrates a direct link between a specific histone residue (H3K4) and histone maintenance at promoters and enhancers, and that H3.3 provides a platform for analyzing the role of histone residues in mammals

Development of novel routes to pyridines

Pyridines occupy a central part in modern day organic chemistry. Recent studies in various fields of chemistry, biology and physics have featured numerous examples and applications of these compounds. The purpose of this study was to produce a library of polysubstituted pyridines, 2,2'-bipyridines and 2,2':6',2"-terpyridines via pathways that allowed unusual or even unique substitution patterns. To achieve a generic pyridine synthesis that delivers a diversity of products tailored to different industrial needs, a strategy by which the target molecule is constructed in a [2+2+2]-manner was chosen, i.e. the six atoms of the pyridine ring and their pendant functionalities are traced back to three building blocks, each delivering two atoms to the pyridine ring. A range of a-acetoxy-a-chloro-P-keto esters were prepared in three steps from commercially available P-keto esters through a-chlorination with sulfuryl chloride, a-acetoxylation with acetic acid and triethylamine and a second a-chlorination in good overall yields (69 — 89 %) without the need for chromatographic purification. These a-acetoxy-a-chloro-j3-keto esters served as equivalents for a,[3-diketo esters (building block 1) in the synthesis of various 1,2,4- triazines through condensation with picolinohydrazonamides or thiosemicarbazides (building block 2). A subsequent aza Diels-Alder reaction of these 1,2,4-triazines with electron-rich dienophiles (building block 3) such as 2,5-norbornadiene, 1-pyrrolidino- 1 -cyclopentene and 2,3-dihydrofuran furnished an array of novel polysubstitued (bi)pyridines. The two-step sequence of condensation and aza Diels-Alder reaction could be advanced into a 'one-pot' synthesis on several occasions. Furthermore, we devised a feasible synthetic alternative towards a,(3-diketo esters. Alpha-picolinoyl-3-keto esters were prepared from the same starting materials as the a-acetoxy-a¬chloro-P-keto esters in a shortened two-step sequence of a-chlorination of P-keto esters with sulfuryl chloride and replacement of the chloro group by a picolinoyl group using picolinic acid and KHCO3. The overall yields of a-picolinoyl-f3-keto esters (55 — 91 %) were comparable to those of the a-acetoxy-a-chloro-P-keto esters. Copper(II) acetate-facilitated methanolysis of a-picolinoyl-P-keto esters and immediate oxidation of the in situ generated a-hydroxy-P-keto esters by excess copper(II) acetate afforded a,(3-diketo esters which reacted with hydrazonamides in the same manner as the a-chloro-a-acetoxy-P-keto esters. However, in terms of product purity and yield the `chloroacetate route' remains the superior strategy

The complex governance of the 2030 Agenda and the steering effects of implementing the SDGs in Brazil (2015-2022)

Agenda 2030 e os Objetivos de Desenvolvimento Sustentável (ODS) foram desenhadospara orientar politicamente países de acordo com a realidade local. A implementaçãodesta agenda no Brasil oscilou entre a governança sem governo e a governança complexacom matiz social. A partir de abordagem qualitativo-interpretativa, discute-se a adesão doBrasil à Agenda 2030 em um processo policêntrico e de base social. Os resultados indicamo papel dos ODS em guiar discussões e ações locais, promovendo integração institucional,formação de uma rede inovadora e uma arquitetura de governança social de governoslocais e atores não estatais.La Agenda 2030 y los Objetivos de Desarrollo Sostenible (ODS) fueron concebidos paraorientar políticamente a los países de acuerdo con sus intereses. La implementación de estaagenda en Brasil ha oscilado entre gobernabilidad sin gobierno y gobernabilidad complejacon dimensión social. Un enfoque cualitativo-interpretativo discute la adhesión de Brasil ala Agenda 2030 en un proceso policéntrico y de base social. Los resultados indican el papelde los ODS en orientar las acciones locales, promoviendo la integración institucional, laformación de una red innovadora y una arquitectura de gobernanza social de los gobiernoslocales y actores no estatales.The 2030 Agenda and the Sustainable Development Goals (SDGs) were conceived to politically guide countries according to their interests. The implementation of this agenda in Brazil has oscillated between governance without government and complex governance with a social dimension. Based on a qualitative-interpretative approach, Brazil’s adherence to the 2030 Agenda is discussed in a polycentric and socially based process. The results indicate the role of the SDGs in guiding local discussions and actions, promoting institutional integration, the formation of an innovative network and an architecture of social governance of local governments and non-state actors

Analysis of induced gamma activation by D-T neutrons in selected fusion reactor relevant materials with EAF-2010

Samples of lanthanum, erbium and titanium which are constituents of structural materials, insulating coatings and tritium breeder for blankets of fusion reactor designs have been irradiated in a fusion peak neutron field. The induced gamma activities were measured and the results were used to check calculations with the European activation system EASY-2010. Good agreement for the prediction of major contributors to the contact dose rate of the materials was found, but for minor contributors the calculation deviated up to 50%

Editorial – Global Politics, the 2030 Agenda and the Sustainable Development Goals (SDG)

The publication of a special edition of Meridiano 47 – Journal of Global Politics about the Agenda 2030 and the Sustainable Development Goals places Brazil and the Global South at the center of one of the most relevant subjects that have been fueling journals, papers, and international conferences all over the world. In fact, this dossier is a genuine intellectual contribution to the debates on the impacts of the 2030 Agenda by debating Challenges to the Global Politics regarding the 2030 Agenda and the SDGs, such as territorialization and levels of implementation, orchestration and accountability, transformative potential of the SDGs, conciliating research with learning and outreach activities and problematizing the theme of indicators. Also, by given a clear cut of the Brazilian perspective on global politics of the SDG.A publicação de uma edição especial do Meridiano 47 - Revista de Política Global sobre a Agenda 2030 e os Objetivos de Desenvolvimento Sustentável coloca o Brasil e o Sul Global no centro dos debates sobre um dos assuntos mais relevantes e que têm animado periódicos, artigos e conferências internacionais no mundo todo. De fato, esse dossiê é uma genuína contribuição intelectual para as discussões sobre os impactos da Agenda 2030, debatendo os desafios à política global em relação à Agenda 2030 e aos ODS, como territorialização e níveis de implementação, orquestração e prestação de contas, potencial transformador dos ODS, conciliação entre pesquisa e atividades de aprendizagem e extensão, bem como problematizando o tema dos indicadores. Além disso, busca fornecer recorte claro da perspectiva brasileira sobre a política global dos ODS

Investigations on CdZnTe-Semiconductor-Detectors for the Search of the Neutrinoless Double Beta Decay

The Cadmium-Zinc-Telluride 0-Neutrino-Double-Beta Research Apparatus (COBRA-Experiment) investigates the theoretically predicted neutrinoless double beta decay (0νββ-decay) to indirectly determine the effective Ma- jorana mass of the electron-neutrino by a measurement of the half-life of the 0νββ-decay using room-temperature semiconducting Cadmium-Zinc- Telluride-detectors (CZT). The detectors are made of elements containing several isotopes that decay via double beta decay (ββ-decay). In such a con- figuration the detector itself becomes the source of the decay and, hence, the efficiency for the detection of such events rises. This work covers the investigations and characterizations made on the CZT detectors used in the COBRA-Experiment, currently running. Prior to in- stallation the physical properties of the detectors are analyzed and during operation the stability of the detectors is monitored. For the laboratory analysis three dedicated setups are developed that allow for detailed inves- tigations of different properties of the detectors. Beside the working point determination and the analysis of the temperature dependence of the de- tector performance, the spatial detector response to localized irradiation is analyzed and a setup to generate a library of specific pulse shapes is designed and operated. Furthermore, an investigation for a possible discrimination of α- and β-decay events based on pulse shape discrimination is performed as well as an analysis of the long term stability of underground operated CZT detectors