A max-flow approach to improved lower bounds for quadratic unconstrained binary optimization (QUBO)

AbstractThe “roof dual” of a QUBO (Quadratic Unconstrained Binary Optimization) problem has been introduced in [P.L. Hammer, P. Hansen, B. Simeone, Roof duality, complementation and persistency in quadratic 0–1 optimization, Mathematical Programming 28 (1984) 121–155]; it provides a bound to the optimum value, along with a polynomial test of the sharpness of this bound, and (due to a “persistency” result) it also determines the values of some of the variables at the optimum. In this paper we provide a graph-theoretic approach to provide bounds, which includes as a special case the roof dual bound, and show that these bounds can be computed in O(n3) time by using network flow techniques. We also obtain a decomposition theorem for quadratic pseudo-Boolean functions, improving the persistency result of [P.L. Hammer, P. Hansen, B. Simeone, Roof duality, complementation and persistency in quadratic 0–1 optimization, Mathematical Programming 28 (1984) 121–155]. Finally, we show that the proposed bounds (including roof duality) can be applied in an iterated way to obtain significantly better bounds. Computational experiments on problems up to thousands of variables are presented

Libertação acidental de gases tóxicos: modelação e avaliação do risco

Doutoramento em Ciências Aplicadas ao AmbienteThe renewed concern in assessing risks and consequences from technological hazards in industrial and urban areas continues emphasizing the development of local-scale consequence analysis (CA) modelling tools able to predict shortterm pollution episodes and exposure effects on humans and the environment in case of accident with hazardous gases (hazmat). In this context, the main objective of this thesis is the development and validation of the EFfects of Released Hazardous gAses (EFRHA) model. This modelling tool is designed to simulate the outflow and atmospheric dispersion of heavy and passive hazmat gases in complex and build-up areas, and to estimate the exposure consequences of short-term pollution episodes in accordance to regulatory/safety threshold limits. Five main modules comprising up-to-date methods constitute the model: meteorological, terrain, source term, dispersion, and effects modules. Different initial physical states accident scenarios can be examined. Considered the main core of the developed tool, the dispersion module comprises a shallow layer modelling approach capable to account the main influence of obstacles during the hazmat gas dispersion phenomena. Model validation includes qualitative and quantitative analyses of main outputs by the comparison of modelled results against measurements and/or modelled databases. The preliminary analysis of meteorological and source term modules against modelled outputs from extensively validated models shows the consistent description of ambient conditions and the variation of the hazmat gas release. Dispersion is compared against measurements observations in obstructed and unobstructed areas for different release and dispersion scenarios. From the performance validation exercise, acceptable agreement was obtained, showing the reasonable numerical representation of measured features. In general, quality metrics are within or close to the acceptance limits recommended for ‘non-CFD models’, demonstrating its capability to reasonably predict hazmat gases accidental release and atmospheric dispersion in industrial and urban areas. EFRHA model was also applied to a particular case study, the Estarreja Chemical Complex (ECC), for a set of accidental release scenarios within a CA scope. The results show the magnitude of potential effects on the surrounding populated area and influence of the type of accident and the environment on the main outputs. Overall the present thesis shows that EFRHA model can be used as a straightforward tool to support CA studies in the scope of training and planning, but also, to support decision and emergency response in case of hazmat gases accidental release in industrial and built-up areas.A renovada preocupação na avaliação dos riscos e consequências dos perigos tecnológicos em zonas industriais e urbanas continua a enfatizar o desenvolvimento de modelos de análise de consequências (AC) à escala local, capazes de simular episódios de poluição de curto prazo e seus efeitos na saúde humana e ambiente resultantes da exposição em situação de acidentes com substâncias perigosas. Neste sentido, o principal objecto desta tese é o desenvolvimento e validação do modelo Efects of Released Hazardous gAses (EFRHA). Esta ferramenta foi desenvolvida para simular a libertação e dispersão atmosférica de gases perigosos pesados e passivos em ambientes de topografia complexa e edificados, bem como, estimar as consequências da exposição a episódios de poluição de curta duração de acordo com limites de segurança e controlo. O modelo é constituído por cinco módulos principais: meteorológico, fontes, terreno, dispersão e efeitos. Diferentes estados físicos e tipos de acidente podem ser analisados. Considerado o elemento principal da ferramenta, o módulo de dispersão é baseado na modelação ‘shallow layer’, que permite considerar a influência de obstáculos na dispersão de gases perigosos. A validação do modelo inclui métodos de análise qualitativa e quantitativa através da comparação dos principais outputs com bases de dados medidos ou simulados. A análise preliminar dos módulos meteorológica e fontes baseada na comparação com resultados de modelos também validados demonstra a correcta descrição das condições ambientais e da variação das características da fonte ao longo da libertação. O módulo de dispersão é comparado com resultados de medições experimentais considerando diferentes condições de libertação e dispersão atmosférica. Em geral, os critérios de qualidade estimados encontram-se dentro dos limites de aceitação para modelos ‘non-CFD’, demonstrando a capacidade para simular razoavelmente a libertação e dispersão atmosférica de gases pesados perigosos em ambientes industriais e urbanos. O modelo EFRHA também foi aplicado a um caso de estudo, o Complexo Químico de Estarreja (ECC), com base num conjunto de cenários de libertação acidental, no âmbito de um estudo de AC. Os resultados demonstram a potencial magnitude dos efeitos na área envolvente ao ECC, bem como a influência das condições meteorológicas e tipo de acidente. De um modo geral, a presente tese demonstra a aplicabilidade do modelo como ferramenta para estudos de CA, bem como no suporte à decisão e preparação de resposta de emergência em situação de libertação acidental em zonas urbanas e industriais

Inflammatory pseudotumors of the paranasal sinuses

Pseudotumor inflamatório pode ser definido como uma lesão que simula neoplasia clínica e radiologicamente. Não se trata de uma entidade clínico-patológica única, mas um termo genérico para qualquer lesão expansiva inflamatória crônica inespecífica. Há poucos relatos de pseudotumor inflamatório em cavidade nasal e seios paranasais. RELATO DE CASOS: Apresentamos três casos de pseudotumor inflamatório em nariz e seios paranasais atendidos na Divisão de Clínica Otorrinolaringológica do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. DISCUSSÃO: Pseudotumor inflamatório de seios paranasais apresenta sintomatologia variável conforme o local de origem. Geralmente, segue curso benigno, porém pode ser localmente agressivo.Inflammatory pseudotumors may be defined as lesions that clinically and radiologically simulate neoplasms. These tumor are not a single clinical-pathological entity, but rather a generic term applied to any nonspecific, chronic, inflammatory expanding lesion. There are few reports of inflammatory pseudotumors in the nasal cavity and paranasal sinuses. CASE REPORT: We report three cases of inflammatory pseudotumors of the nose and paranasal sinuses seen at the Division of Otolaryngology of the Medical School University Hospital, Sao Paulo University. DISCUSSION: Inflammatory pseudotumors of the paranasal sinuses present a variety of symptoms according to the site

Cartografia e fantasia: desenvolvendo a cidadania e os raciocínios geográficos a partir das autorias infantis

The contributions of School Cartography to the development of geographic reasoning and to the interpretation of the spatiality of phenomena are explored in this article, from an experience with elementary school students of a municipal public school in Rio de Janeiro. We start from the references of the Cultural-Historical Theory, the construction of experiential maps and the multilingualism in cartography, guiding the proposal against the production and teaching of a technical cartography, supposedly objective, based on calculations and conventions committed to the idea of precision. In this sense, we value the lived space, subjectivity, creativity and authorship of the students, as well as fantasy and playfulness. The experience consisted of the collective, collaborative and itinerant elaboration of a map named "Fantastic Continent" (referring to the proposal of a cartography of the fantastic), which "traveled" through the sixth, seventh and eighth grade classes of a municipal school located in the adjacencies of the Maré slum, in the city of Rio de Janeiro. We verified the production of fantastic cartography and narratives dense with spatiality that communicated information of a non-static, under construction, unfinished real-fictional geographic space. Therefore, the construction of fantastic cartographies within the framework of experiential maps expands the possibilities of a Geography teaching committed to the development of a critical and active citizenship, which makes use of imagination to create not only fiction tales, but, other spaces - spaces for other social relations - where autonomy and participation can flourish for democracy.Los aportes de la Cartografía Escolar para el desarrollo del razonamiento geográfico y para la interpretación de la espacialidad de los fenómenos son explorados en este artículo, a partir de una experiencia con alumnos de primaria de una escuela pública municipal de Río de Janeiro. Partimos de los referentes de la Teoría Histórico-Cultural, la construcción de mapas vivenciales y el multilingüismo en la cartografía, adelantando la propuesta contra la producción y enseñanza de una cartografía técnica, supuestamente objetiva, basada en cálculos y convenciones comprometidas con la idea de exactitud. En este sentido, se valora el espacio vivido, la subjetividad, la creatividad y la autoría de los alumnos, así como la fantasía y el juego. La experiencia consistió en la elaboración colectiva, colaborativa e itinerante de un mapa denominado "Continente Fantástico" (haciendo referencia a la propuesta de una cartografía de lo fantástico), que "viajó" por las clases de sexto, séptimo y octavo año de una escuela municipal ubicada en las adyacencias de la favela Maré, en la ciudad de Río de Janeiro. Verificamos la producción de una cartografía fantástica y densas narrativas de espacialidad que comunicaban información de un espacio geográfico no estático, en construcción, no concluido, real-ficcional. Por lo tanto, la construcción de cartografías fantásticas en el ámbito de los mapas vivenciales amplía las posibilidades de una enseñanza de la Geografía comprometida con el desarrollo de una ciudadanía crítica y activa, que hace uso de la imaginación para crear no sólo relatos de ficción, sino, otros espacios -espacios de otras relaciones sociales- donde pueda florecer la autonomía y la participación para la democracia.As contribuições da Cartografia Escolar para o desenvolvimento do raciocínio geográfico e para a interpretação da espacialidade dos fenômenos são exploradas neste artigo, a partir de uma experiência com estudantes do ensino fundamental de uma escola pública municipal do Rio de Janeiro. Partimos dos referenciais da Teoria Histórico-cultural, da construção de mapas vivenciais e dos multiletramentos em cartografia, encaminhando a proposta na contramão da produção e do ensino de uma cartografia tecnicista, pretensamente objetiva, fundamentada em cálculos e convenções comprometidos com a ideia de precisão. Neste sentido, valoriza-se o espaço vivido, a subjetividade, a criatividade e autoria dos discentes, tal como, a fantasia e a ludicidade. A experiência consistiu na elaboração coletiva, colaborativa e itinerante de um mapa denominado “Continente fantástico" (fazendo referência à proposta de uma cartografia do fantástico), que “percorreu” as turmas de sexto, sétimo e oitavo ano de uma escola municipal localizada nas adjacências da favela da Maré, na cidade do Rio de Janeiro. Verificamos a produção de uma cartografia fantástica e de narrativas densas de espacialidade que comunicavam informações de um espaço geográfico real-ficcional não-estático, em construção, não-concluído. Portanto, a construção de cartografias fantásticas no âmbito de mapas vivenciais amplia as possibilidades de um ensino de Geografia comprometido com o desenvolvimento de uma cidadania crítica e ativa, que lança mão da imaginação para criar não apenas contos de ficção, mas, outros espaços – espaços para outras relações sociais – onde a autonomia e a participação podem florescer para a democracia

pavarotti encodes a kinesin-like protein required to organize the central spindle and contractile ring for cytokinesis

Mutations in the Drosophila gene pavarotti result in the formation of abnormally large cells in the embryonic nervous system. In mitotic cycle 16, cells of pav mutant embryos undergo normal anaphase but then develop an abnormal telophase spindle and fail to undertake cytokinesis. We show that the septin Peanut, actin, and the actin-associated protein Anillin, do not become correctly localized in pav mutants. pav encodes a kinesin-like protein, PAV–KLP, related to the mammalian MKLP-1. In cellularized embryos, the protein is localized to centrosomes early in mitosis, and to the midbody region of the spindle in late anaphase and telophase. We show that Polo kinase associates with PAV–KLP with which it shows an overlapping pattern of subcellular localization during the mitotic cycle and this distribution is disrupted in pavmutants. We suggest that PAV–KLP is required both to establish the structure of the telophase spindle to provide a framework for the assembly of the contractile ring, and to mobilize mitotic regulator proteins

pavarotti encodes a kinesin-like protein required to organize the central spindle and contractile ring for cytokinesis

Mutations in the Drosophila gene pavarotti result in the formation of abnormally large cells in the embryonic nervous system. In mitotic cycle 16, cells of pav mutant embryos undergo normal anaphase but then develop an abnormal telophase spindle and fail to undertake cytokinesis. We show that the septin Peanut, actin, and the actin-associated protein Anillin, do not become correctly localized in pav mutants. pav encodes a kinesin-like protein, PAV–KLP, related to the mammalian MKLP-1. In cellularized embryos, the protein is localized to centrosomes early in mitosis, and to the midbody region of the spindle in late anaphase and telophase. We show that Polo kinase associates with PAV–KLP with which it shows an overlapping pattern of subcellular localization during the mitotic cycle and this distribution is disrupted in pavmutants. We suggest that PAV–KLP is required both to establish the structure of the telophase spindle to provide a framework for the assembly of the contractile ring, and to mobilize mitotic regulator proteins

The expression of tubulin cofactor A (TBCA) is regulated by a noncoding antisense Tbca RNA during testis maturation

BACKGROUND: Recently, long noncoding RNAs have emerged as pivotal molecules for the regulation of coding genes' expression. These molecules might result from antisense transcription of functional genes originating natural antisense transcripts (NATs) or from transcriptional active pseudogenes. TBCA interacts with β-tubulin and is involved in the folding and dimerization of new tubulin heterodimers, the building blocks of microtubules. METHODOLOGY/PRINCIPAL FINDINGS: We found that the mouse genome contains two structurally distinct Tbca genes located in chromosomes 13 (Tbca13) and 16 (Tbca16). Interestingly, the two Tbca genes albeit ubiquitously expressed, present differential expression during mouse testis maturation. In fact, as testis maturation progresses Tbca13 mRNA levels increase progressively, while Tbca16 mRNA levels decrease. This suggests a regulatory mechanism between the two genes and prompted us to investigate the presence of the two proteins. However, using tandem mass spectrometry we were unable to identify the TBCA16 protein in testis extracts even in those corresponding to the maturation step with the highest levels of Tbca16 transcripts. These puzzling results led us to re-analyze the expression of Tbca16. We then detected that Tbca16 transcription produces sense and natural antisense transcripts. Strikingly, the specific depletion by RNAi of these transcripts leads to an increase of Tbca13 transcript levels in a mouse spermatocyte cell line. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that Tbca13 mRNA levels are post-transcriptionally regulated by the sense and natural antisense Tbca16 mRNA levels. We propose that this regulatory mechanism operates during spermatogenesis, a process that involves microtubule rearrangements, the assembly of specific microtubule structures and requires critical TBCA levels

JAZF1-SUZ12 dysregulates PRC2 function and gene expression during cell differentiation

Polycomb repressive complex 2 (PRC2) methylates histone H3 lysine 27 (H3K27me3) to maintain gene repression and is essential for cell differentiation. In low-grade endometrial stromal sarcoma (LG-ESS), the PRC2 subunit SUZ12 is often fused with the NuA4/TIP60 subunit JAZF1. We show that JAZF1-SUZ12 dysregulates PRC2 composition, genome occupancy, histone modification, gene expression, and cell differentiation. Loss of the SUZ12 N terminus in the fusion protein abrogates interaction with specific PRC2 accessory factors, reduces occupancy at PRC2 target genes, and diminishes H3K27me3. Fusion to JAZF1 increases H4Kac at PRC2 target genes and triggers recruitment to JAZF1 binding sites during cell differentiation. In human endometrial stromal cells, JAZF1-SUZ12 upregulated PRC2 target genes normally activated during decidualization while repressing genes associated with immune clearance, and JAZF1-SUZ12-induced genes were also overexpressed in LG-ESS. These results reveal defects in chromatin regulation, gene expression, and cell differentiation caused by JAZF1-SUZ12 that may underlie its role in oncogenesis