1,218 research outputs found

    Network conduciveness with application to the graph-coloring and independent-set optimization transitions

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    We introduce the notion of a network's conduciveness, a probabilistically interpretable measure of how the network's structure allows it to be conducive to roaming agents, in certain conditions, from one portion of the network to another. We exemplify its use through an application to the two problems in combinatorial optimization that, given an undirected graph, ask that its so-called chromatic and independence numbers be found. Though NP-hard, when solved on sequences of expanding random graphs there appear marked transitions at which optimal solutions can be obtained substantially more easily than right before them. We demonstrate that these phenomena can be understood by resorting to the network that represents the solution space of the problems for each graph and examining its conduciveness between the non-optimal solutions and the optimal ones. At the said transitions, this network becomes strikingly more conducive in the direction of the optimal solutions than it was just before them, while at the same time becoming less conducive in the opposite direction. We believe that, besides becoming useful also in other areas in which network theory has a role to play, network conduciveness may become instrumental in helping clarify further issues related to NP-hardness that remain poorly understood

    Predictors of walking capacity in peripheral arterial disease patients

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    OBJECTIVE: To estimate walking capacity in intermittent claudication patients through a prediction model based on clinical characteristics and the walking impairment questionnaire. METHODS: The sample included 133 intermittent claudication patients of both genders aged between 30 and 80 years. Data regarding clinical characteristics, the walking impairment questionnaire and treadmill walking test performance were obtained. Multiple regression modeling was conducted to predict claudication onset distance and total walking distance using clinical characteristics (age, height, mass, body mass index, ankle brachial index lower, gender, history of smoking and co-morbid conditions) and walking impairment questionnaire responses. Comparisons of claudication onset distance and total walking distance measured during treadmill tests and estimated by a regression equation were performed using paired t-tests. RESULTS: Co-morbid conditions (diabetes and coronary artery disease) and questions related to difficulty in walking short distances (walking indoors - such as around your house and walking 5 blocks) and at low speed (walking 1 block at average speed - usual pace) resulted in the development of new prediction models high significant for claudication onset distance and total walking distance (p0.05) were observed. CONCLUSION: The current study demonstrated that walking capacity can be adequately estimated based on co-morbid conditions and responses to the walking impairment questionnaire

    Cutaneous streptococcal abscess treated by photodynamic therapy

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    Background: Photodynamic therapy has been investigated in different areas of health through experimental conditions. Its action can alter fundamental structures for the survival of microorganisms without any development of microbial resistance.Materials and Methods: Young sheep presenting with abscess in the left forelimb caused by Streptococcus spp. was previously treated with antibiotics. There was no clinical improvement with the treatments, and the bacteria presented sensitivity in vitro. Therefore, Photodynamic therapy associating methylene blue and red laser (660 nm) was used to treat the abscess.Results: After a day of treatment, complete healing was witnessed with no recurrence was observed during the 3-month follow-up period.Conclusion: The scientific results of the antimicrobial effect of PDT proved to be a therapeutic option with great potential for clinical application.Keywords: Photoinactivation, Laser, Sheep, Streptococcus spp

    Climate change resilience of a globally important sea turtle nesting population

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    This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordFew studies have looked into climate change resilience of populations of wild animals. We use a model higher vertebrate, the green sea turtle, as its life history is fundamentally affected by climatic conditions, including temperature-dependent sex determination and obligate use of beaches subject to sea level rise (SLR). We use empirical data from a globally important population in West Africa to assess resistance to climate change within a quantitative framework. We project 200 years of primary sex ratios (1900–2100) and create a digital elevation model of the nesting beach to estimate impacts of projected SLR. Primary sex ratio is currently almost balanced, with 52% of hatchlings produced being female. Under IPCC models, we predict: (a) an increase in the proportion of females by 2100 to 76%–93%, but cooler temperatures, both at the end of the nesting season and in shaded areas, will guarantee male hatchling production; (b) IPCC SLR scenarios will lead to 33.4%–43.0% loss of the current nesting area; (c) climate change will contribute to population growth through population feminization, with 32%–64% more nesting females expected by 2120; (d) as incubation temperatures approach lethal levels, however, the population will cease growing and start to decline. Taken together with other factors (degree of foraging plasticity, rookery size and trajectory, and prevailing threats), this nesting population should resist climate change until 2100, and the availability of spatial and temporal microrefugia indicates potential for resilience to predicted impacts, through the evolution of nest site selection or changes in nesting phenology. This represents the most comprehensive assessment to date of climate change resilience of a marine reptile using the most up-to-date IPCC models, appraising the impacts of temperature and SLR, integrated with additional ecological and demographic parameters. We suggest this as a framework for other populations, species and taxa.Portuguese Foundation for Science and TechnologyMAVA FoundationRufford Foundatio

    The combinatorics of resource sharing

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    We discuss general models of resource-sharing computations, with emphasis on the combinatorial structures and concepts that underlie the various deadlock models that have been proposed, the design of algorithms and deadlock-handling policies, and concurrency issues. These structures are mostly graph-theoretic in nature, or partially ordered sets for the establishment of priorities among processes and acquisition orders on resources. We also discuss graph-coloring concepts as they relate to resource sharing.Comment: R. Correa et alii (eds.), Models for Parallel and Distributed Computation, pp. 27-52. Kluwer Academic Publishers, Dordrecht, The Netherlands, 200

    Immunomodulatory properties of Musa paradisiaca L. inflorescence in Combined Allergic Rhinitis and Asthma Syndrome (CARAS) model towards NFκB pathway inhibition

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    Musa paradisiaca L. (Musaceae), a tropical plant named banana is used as food and as medicine in Brazil. Banana inflorescence, popularly known as mangará, presents several biological activities including anti-inflammatory effects. Here, we demonstrated the immunomodulatory activity of banana inflorescence extract (HEM) on a mice model of combined allergic rhinitis and asthma syndrome (CARAS) and in human macrophages. The HEM inhibited the eosinophil migration, production of cytokines as IL-4, IL-5, IL-13, and IL-17A dependent on IFN-¿ production in the airway. The mechanism of the extract was, in part, by the NF-¿B signaling pathway inhibition. Besides, the HEM decreased expression of the CD86 and HLA-DR receptors on human M1 macrophages independently of M2 modulation. Therefore, we infer that the inflorescence, a disposable material from the banana crops, has anti-allergic property in the CARAS model and modulates the human macrophages, characterizing it as biologically important material for the production of phytomedicine.This work was supported by Brazilian agencies National Council for Scientific and Technological Development (CNPq), Coordination for the Improvement of Higher Education Personnel (CAPES), Institute for Research and Innovation in Health (I3S) and National Institute of Biomedical Engineering (INEB). The authors would like to thank Serviço de Imunohemoterapia of Centro Hospitalar Universitário de São João (CHUSJ), Porto, Portugal, for kindly donating Buffy Coats. The authors are also grateful for the valuable assistance provided by agencies, institutes and collaborators. This work was supported by Brazilian agencies National Council for Scientific and Technological Development (CNPq), Coordination for the Improvement of Higher Education Personnel (CAPES), Institute for Research and Innovation in Health (I3S) and National Institute of Biomedical Engineering (INEB). The authors would like to thank Serviço de Imunohemoterapia of Centro Hospitalar Universitário de São João (CHUSJ), Porto, Portugal, for kindly donating Buffy Coats. The authors are also grateful for the valuable assistance provided by agencies, institutes and collaborators

    Efeitos antiangiogênicos in vivo convalidam a atividade antineoplásica potencial do metiljasmonato

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    Molecular plant components have long been aimed at the angiogenesis and anti-angiogenesis pathways, and have been tested as sources for antineoplasic drugs with promising success. The present work deals with the anti-angiogenic effects of Methyl Jasmonate. Jasmonate derivatives were demonstrated to selectively damage the mitochondria of cancer cells. In vitro, 1-10 mM Methyl Jasmonate induced the cell death of the human umbilical vein endothelial cells (HUVEC) and the Murine melanoma cells (B16F10), while micromolar concentrations were ineffective. In vivo, comparable concentrations were toxic and reduced the vessel density of the Chorioallantoic Membrane of the Chicken Embryo (CAM). However, 1-10 µM concentrations produced a complex effect. There was increased capillary budding, but the new vessels were leakier and less organised than corresponding controls. It is suggested that not only direct toxicity, but also the drug effects upon angiogenesis are relevant to the antineoplasic effects of Methyl Jasmonate.Moléculas de origem vegetal são, há muito, conhecidas como substâncias ativas sobre as vias de angiogênese e antiangiogênese e foram testadas como fonte de drogas antineoplásicas com sucesso promissor. Este trabalho trata dos efeitos antiangiogênicos do Metiljasmonato, um protótipo da família dos derivados do ácido jasmônico, que danificam seletivamente a mitocôndria de células neoplásicas. In vitro, metiljasmonato 1-10 mM promoveu a morte celular de células endoteliais humanas de cordão umbilical (HUVEC) e de melanoma murino (B16F10); concentrações micromolares foram inócuas. In vivo, concentrações equivalentes foram tóxicas e reduziram a densidade de vasos em membranas corioalantoicas de embrião de galinha (CAM). Entretanto, concentrações entre 1-10 µM produziram um efeito complexo. Ocorreu aumento no brotamento capilar, mas os novos vasos apresentaram-se frágeis e menos organizados que os controles correspondentes. Sugere-se que, além da toxicidade direta contra as células tumorais, a ação do metiljasmonato sobre a angiogênese seja relevante para seu efeito antineoplásico

    Strategies to mitigate the emission of methane in pastures: Enteric methane: A review

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    The global population reached 7.9 billion in 2021, which represents a 160% increase in the number of people to be fed since 1960. Agricultural systems must sustainably meet food demand for this growing population while minimizing or mitigating potential environmental impacts, which are of growing concern to both consumers and the scientific community. High protein animal products (meat and milk) play a crucial part in human nutrition and pastures represent ~20% of the planet’s surface. Pastoral areas have a great influence on both ecological balance and human subsistence. Ruminant livestock production systems are hotly debated because of the emission of methane, which is produced during enteric fermentation of ingested food within the rumen. Methanogenesis is a naturally occurring process in the digestive system of ruminant animals and ingesting a high-quality diet has been shown to reduce methane production. An additional function of pastoral grasslands is the capacity of the soils to operate as carbon sinks. Well managed pastures absorb carbon from the atmosphere where it can add to soil organic matter directly, through residue decomposition or excrement returns. However, in Brazil and globally, the efficiency of animal productivity tends to be lower in extensively grazed farming systems. Changes to pasture and grazing management in combination with the adoption of technology is necessary to improve the quality of pastures, increase animal productivity, and consequently reduce methane emissions from ruminant livestock. This review will discuss how to improve the conversion efficiency using pasture management to reduce or mitigate enteric methane production
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