Bin Packing and Related Problems: General Arc-flow Formulation with Graph Compression

We present an exact method, based on an arc-flow formulation with side constraints, for solving bin packing and cutting stock problems --- including multi-constraint variants --- by simply representing all the patterns in a very compact graph. Our method includes a graph compression algorithm that usually reduces the size of the underlying graph substantially without weakening the model. As opposed to our method, which provides strong models, conventional models are usually highly symmetric and provide very weak lower bounds. Our formulation is equivalent to Gilmore and Gomory's, thus providing a very strong linear relaxation. However, instead of using column-generation in an iterative process, the method constructs a graph, where paths from the source to the target node represent every valid packing pattern. The same method, without any problem-specific parameterization, was used to solve a large variety of instances from several different cutting and packing problems. In this paper, we deal with vector packing, graph coloring, bin packing, cutting stock, cardinality constrained bin packing, cutting stock with cutting knife limitation, cutting stock with binary patterns, bin packing with conflicts, and cutting stock with binary patterns and forbidden pairs. We report computational results obtained with many benchmark test data sets, all of them showing a large advantage of this formulation with respect to the traditional ones

Microbial dynamics and human health risks at the beach – Will climate change matter?

Beaches provide recreational opportunities, relief from hot weather, and economic benefits to coastal communities. Visitors to the beach may be exposed to microbial contaminants and pathogens via water, sand, and aerosols. Water and sand coincide at the beach, providing an environment with unique advantages and challenges to pathogen introduction, growth and persistence, transport, and exchange among habitats. Advantages, such as refuge from predators in sand biofilms, and challenges, such as the relatively dry environment, may be both exacerbated and complicated by seasonal variability and predicted long-term anthropogenic climate change. Human exposure to waterborne pathogens will likely be amplified in the face of predicted extreme rain events, warming of water, and sea level rise, combined with urbanization and the popularity of beach activities. Such changes may also alter microbial dynamics at beaches, potentially impacting assumptions and population relationships used in mechanistic water quality and E. coli concentration models as well as quantitative microbial risk assessment frameworks. With model refinement and parameter development designed to fill critical knowledge gaps, predictive models of fecal indicator bacteria and pathogen fate and transport can help to characterize the risk of infectious disease from recreational water use. Here, we not only present a conceptual model that may serve as a first step toward inclusion of biofilm mechanics at beaches, but we also discuss potential approaches to incorporate sand-water interactions into hydrodynamic coastal models for enhanced beach health prediction. While beach health and water quality have long been active areas of research, the sand and sand-water interface habitats at beaches remain relatively unexplored. Recent work has shown that sand can be a reservoir of microbial contaminants at beaches, signaling a potential paradigm shift in both research and management of recreational water and beaches to a more holistic, beachshed-based model, as further detailed in Weiskerger et al. (doi: 10.20944/preprints201901.0225.v1).info:eu-repo/semantics/publishedVersio

Exposure to fungal particles in sand. Why only water quality is assessed for safety in recreational settings?

Fungi were never introduced to water quality regulations, the incidence of fungal infections worldwide is growing, and changes in antimicrobial resistance patterns are taking place. The presence of fungi in different types of water has been thoroughly investigated during the past 30 years only in Europe, and more than 400 different species were reported from ground-, surface-, and tap-water. The most frequently reported fungi, however, were not waterborne, but are frequently related to soil, air, and food.N/

Assessing the Potential of FT-IR to Identify Clinical Strains of Candida spp

Produto de um estágio curricular21 clinical isolates of Candida spp were examined by FT-IR in order to compare identification using FT-IR with biochemical identification (bioMerieux®). FT-IR revealed itself as a fast and effective method for identification of the strains tested as all were placed into the appropriate species, including one which was misidentified by the biochemical method.Instituto Nacional de Saúde Doutor Ricardo Jorg

Investigating correlation of faecal indicator bacteria and potential pathogenic fungi on Dublin beaches in the interest of public health

Sandy beaches are usually the preferred location for leisure activities but may pose a risk to public health in particular to children, the elderly and immuno compromised individuals Beach sand and marine water may be a reservoir of opportunistic and pathogenic microbes, as well as faecal indicator bacteria (that influence the bathing water quality status. The growth and the proliferation of microbes in beach sand and water are not restricted to bacteria but include also different groups of fungi such as potentially pathogenic and allergenic moulds, yeasts and dermatophytes Currently, no clear guidance about pathogenic fungi levels in relation to public health is available for these environments.info:eu-repo/semantics/publishedVersio

Cultivo de microalgas do género Botryococcus visando a produção de biodiesel

Tese de mestrado em Biologia (Biologia Celular e Biotecnologia), apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2009O mundo encontra-se presentemente confrontado com dupla crise, a escassez das limitadas fontes de combustíveis fósseis e a degradação ambiental. Enquanto a economia mundial demanda cada vez mais por combustíveis a baixo custo para os sistemas industriais e de transportes, existe uma tremenda necessidade de combater as causas e os já existentes efeitos das alterações climáticas por estes causados. Todavia, quando parecia imprescindível o desenvolvimento de combustíveis renováveis neutras em emissões nocivas, tornou-se claro que a primeira geração de biocombustíveis não atinge os limites da demanda e tampouco contribui para a mitigação das alterações climáticas. Daí o interesse no desenvolvimento de uma segunda geração de biocombustíveis produzidos de fontes não alimentares, tais como as microalgas, as quais apresentam grandes perspectivas a longo prazo. Ao contrário das plantas terrestres, as microalgas crescem extremamente rápido em qualquer lado e algumas espécies são ricas em óleo, potencial que representa uma grande vantagem. A microalga verde Botryococcus braunii, com vasta distribuição por todos os continentes, é caracterizada pela sua organização colonial e pela sua espantosa habilidade de produzir lípidos e hidrocarbonetos de cadeia longa que podem atingir de 15% a 75% do peso seco o que tem atraído cada vez maior atenção nas últimas duas décadas no sentido de exploração desta espécie visando a produção de biodiesel. Esta tese foi desenvolvida no sentido de investigar a potencialidade do uso de estirpes locais (portuguesas) desta espécie como substrato para o biodiesel. Pelos resultados obtidos nas experiências realizadas, a taxa máxima de crescimento conseguida durante a fase exponencial foi de 61 mg/L*dia (peso seco). Constatou-se que crescimento e a produção lipídica das estirpes cultivadas são influenciados pelas condições de cultura daí a necessidade de optimizá-las. Todavia, estas estirpes mostram-se capazes de crescer, produzir óleos e absorver nutrientes em culturas em águas residuais. A percentagem máxima obtida para o extracto lipídico foi de 36% da biomassa seca o que está de acordo com vários resultados que permitiram considerar esta espécie como potencial substrato para o biodiesel. Este facto é também apoiado pela predominância do ácido oleico (C18:1, 42% a 66%) e do ácido palmítico (C16:0, 8% a 18%) no extracto lipídico dado que os metil ésteres desses ácidos gordos (FAME) são os ideais para a produção de biodiesel. Em suma, apesar de estas estirpes de B. braunii apresentarem crescimento relativamente lento, produzem conteúdo e constituição lipídica considerável que no mínimo justifica mais investimento num melhor estudo da sua biologia.The world is presently confronted with twin crises, depletion of the finite reserves of fossil fuel and environmental degradation. While the global economy increasingly demands for low-cost fuels for industrial and transportation systems, there is a tremendous need to combat the causes and effects of existing climate change caused by them. However, when it seemed essential to develop renewable fuels neutral in harmful emissions, it became clear that the first generation of biofuels does not reach the limits of demand, nor contribute to the climate change mitigation. Hence the interest in developing a second generation biofuels produced from non-food feedstocks such as microalgae, which potentially offer greatest opportunities in the longer term. Unlike other oil crops, microalgae grow extremely rapidly in any anywhere and many are exceedingly rich in oil, potential that represents a great advantage. The green microalga Botryococcus braunii (Chlorophyceae), which is widely distributed on all continents, is characterized by an original organization of colonies and an unusual capacity to produce unsaturated long-chain hydrocarbons, reaching contents ranging from 15% to 75% of its dry weight. This characteristic has attracted increasingly more attention in the last two decades in attempts to exploit this species for renewable biodiesel. This thesis was developed to investigate the potential of the local strains of this species as a substrate for biodiesel. From the results obtained in experiments carried out the maximum growth rate achieved was 61 mg/L*day (dry weight). We found that growth and lipid production of cultivated strains are influenced by culture conditions hence the need to optimize them. However, these strains appear to be able to grow, produce oil and absorb nutrients in wastewater cultures. The maximum lipid extract obtained was 36% of dry matter which is in agreement with several results that allow considering this species as a potential substrate for biodiesel. This is also supported by the predominance of oleic acid (C18:1, 42% to 63%) and palmitic acid (C16:0, 8 to 18%) in the lipid extract as the methyl esters of these fatty acids (FAME) are ideal for the production of biodiesel. In short, although these strains of B. braunii present relatively slow growth, they produce considerable lipid content that at least warrants further investment in a better study of its biology

O Consumo Alcoólico Estará Aumentado em Adolescentes com Fat Bingeing?

Evidence has been suggesting that neurochemical and behavioral adaptations emerging during one addictive behavior may enable a subsequent, different, addiction, even when the first one has ended. Such association seems remarkably accurate to fat bingeing and ethanol consumption, which constitute a relevant example of addictive patterns sequential association, particularly in adolescence. Therefore, the main purpose of the following review is to comprehend if adolescents who have engaged on fat bingeing escalated their ethanol consumption, after fat bingeing terminus, and secondly, in a positive scenario, to highlight why such association may happen. After searching databases such as MEDLINE (PubMed) and Clarivate Analytics Web of Science, all articles focused on adolescent humans or adolescent rats or adolescent mice, that included topics on fat bingeing and consequent ethanol consumption, were considered. Gathered results strengthened the referred hypothesis. Reports stating that adolescent fat bingers engage on escalated ethanol consumption were fundamentally supported by a prevalent fast food and ethanol cultures, bingers ‘shared personality traits, adolescence ‘susceptibilities for addictive behaviors and neurochemical and behavioral craving installment after fat bingeing cessation. Given that adolescence is a key structural and functional phase of human development, and that fat and ethanol consumption are linked to harmful physiological and social effects, priority must be given to multidisciplinary interventions aiming to challenge addictions, both pharmacologically and psychotherapeutically.A evidência tem sugerido que existem alterações, de índole neuroquímica e comportamental, que ocorrem durante uma perturbação aditiva e que propiciam uma perturbação aditiva subsequente, inclusive após a primeira ter terminado. Esta associação, entre dependências de substâncias, parece ser bastante representativa para fat bingeing e consumo alcoólico, que constituem, então, um exemplo representativo de associação sequencial entre perturbações aditivas, particularmente na adolescência. Assim, o objetivo principal da seguinte revisão é verificar se adolescentes com fat bingeing, tiveram aumento do consumo alcoólico, após término do fat bingeing, e num cenário positivo, compreender porque é que tal associação acontece. Depois de uma pesquisa em bases de dados, como a MEDLINE (PubMed) e a Clarivate Analytics Web of Science, foram considerados os artigos que incluíram fat bingeing e consumo alcoólico em adolescentes, quer humanos quer ratos. Os resultados reunidos defendem fortemente a hipótese questionada. Os diferentes estudos, que afirmaram que adolescentes com fat bingeing têm consumo alcoólico aumentado, baseiam‑se, fundamentalmente: na vigente cultura de fat food e consumo alcoólico, nos traços de personalidade transversais a doentes com dependência de substâncias, nas suscetibilidades inerentes à própria adolescência para dependência, e na instalação neuroquímica e comportamental de craving, após a cessação de fat bingeing. Tendo em conta que a adolescência é uma fase chave no desenvolvimento estrutural e funcional do ser humano, e conhecendo os efeitos pejorativos, fisiológicos e sociais, do fat bingeing e do consumo alcoólico, é recomendado que seja dada prioridade a intervenções multidisciplinares, de nível psicoterapêutico e farmacológico, que possam combater as perturbações consideradas