340 research outputs found

    Mitigating Air Delay: An analysis of the Collaborative Trajectory Options Program

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    Congestion is a problem at major airports in the world. Airports, especially high-traffic ones, tend to be the bottleneck in the air traffic control system. The problem that arises for the airspace planner is how to mitigate air congestion and its consequent delay, which causes increased cost for airlines and discomfort for passengers. Most congestion problems are fixed on the day of operations in a tactically manner using operational enhancements measures. Collaborative Trajectory Options Program (CTOP) aims to improve air traffic management (ATM) considering National Airspace System (NAS) users business goals, particularities faced by each flight and airspace restrictions, making this process more flexible and financially stable for those involved. In CTOP, airlines share their route preferences with the air control authority, combining delay and reroute. When CTOP is created, each airline might decide its strategy without knowledge of other airline’s flights. Current solutions for this problem are based on greedy methods and game theory. There is potential space to improve. This paper examines CTOP and identifies important strategic changes to ATM adopting this philosophy, particularly in Brazil. Document type: Articl

    An ``Improved" Lattice Study of Semi-leptonic Decays of D-Mesons

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    We present results of a lattice computation of the matrix elements of the vector and axial-vector currents which are relevant for the semi-leptonic decays D→KD \rightarrow K and D→K∗D \rightarrow K^*. The computations are performed in the quenched approximation to lattice QCD on a 243×4824^3 \times 48 lattice at β=6.2\beta=6.2, using an O(a)O(a)-improved fermionic action. In the limit of zero lepton masses the semi-leptonic decays D→KD \rightarrow K and D→K∗D \rightarrow K^* are described by four form factors: fK+,V,A1f^{+}_K,V,A_1 and A2A_2, which are functions of q2q^2, where qμq^{\mu} is the four-momentum transferred in the process. Our results for these form factors at q2=0q^2=0 are: f^+_K(0)=0.67 \er{7}{8} , V(0)=1.01 \err{30}{13} , A_1(0)=0.70 \err{7}{10} , A_2(0)=0.66 \err{10}{15} , which are consistent with the most recent experimental world average values. We have also determined the q2q^2 dependence of the form factors, which we find to be reasonably well described by a simple pole-dominance model. Results for other form factors, including those relevant to the decays \dpi and \drho, are also given.Comment: 41 pages, uuencoded compressed postscript file containing 14 figures, LaTeX, Edinburgh Preprint 94/546 and Southampton Preprint SHEP 93/94-3

    Colloid-stabilized emulsions: behaviour as the interfacial tension is reduced

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    We present confocal microscopy studies of novel particle-stabilized emulsions. The novelty arises because the immiscible fluids have an accessible upper critical solution temperature. The emulsions have been created by beginning with particles dispersed in the single-fluid phase. On cooling, regions of the minority phase nucleate. While coarsening these nuclei become coated with particles due to the associated reduction in interfacial energy. The resulting emulsion is arrested, and the particle-coated interfaces have intriguing properties. Having made use of the binary-fluid phase diagram to create the emulsion we then make use of it to study the properties of the interfaces. As the emulsion is re-heated toward the single-fluid phase the interfacial tension falls and the volume of the dispersed phase drops. Crumpling, fracture or coalescence can follow. The results show that the elasticity of the interfaces has a controlling influence over the emulsion behaviour.Comment: Submitted for the proceedings of the 6th Liquid Matter Conference, held in Utrecht (NL) in July 200

    Influência da temperatura no comportamento alimentar e interação de filhotes de Kinosternon scorpioides em cativeiro.

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    O muçuã (Kinosternon scorpioides) é um cágado bastante apreciado em toda a região amazônica, sendo um quelônio com características zootécnicas promissoras na aquicultura. Contudo, há poucos estudos que abordem o comportamento alimentar desta espécie em cativeiro. Portanto, objetivou-se com o presente estudo avaliar a influencia da temperatura no comportamento alimentar e a interação de filhotes de muçuã (Kinosternon scopioides), mantidos em três diferentes temperaturas (29,5ºC, 31,5ºC e 33,5ºC). O experimento foi conduzido no Projeto Bio-Fauna/ISARH/UFRA, sediado em Belém, Pará. Um total de 84 filhotes de muçuãs foram subdivididos em seis lotes-berçário, distribuídos dois a dois em estufas mantidas sob diferentes temperaturas, 29,5ºC, 31,5ºC e 33,5ºC, durante os primeiros 90 dias de vida. Os animais foram alimentados com ração para peixe, na proporção de 2% do peso vivo/dia, distribuída em ofertas semanais. Quinzenalmente foram realizadas pesagens e medições individuais, para avaliação do desenvolvimento corpóreo e ajuste de alimentação. Constatou-se efeito significativo da temperatura em todos os parâmetros analisados. Durante o experimento foi notado uma diminuição na frequência alimentar em todos os tratamentos, porém os animais da temperatura mais alta do experimento (33,5ºC) apresentaram a maior diminuição no interesse pelo alimento durante o período de oferta/observação, portanto os mesmos tiveram o pior desempenho quando comparado aos demais lotes

    Antifungal activity of the isolated from caatinga actinobacteria in control of Pythium aphanidermatum.

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    The Caatinga is a biome located in a semiarid region of northeastern Brazil. It consists of various ecosystems, presented a unique environmental system of this country. Because it is an environment with unique characteristics, recent studies have revealed the private wealth of this biome in terms of microbial biodiversity. Microorganisms found in this habitat may present specific mechanisms to ensure their survival in this environment that provides extreme conditions, such as temperature changes, intense solar radiation and hydrous stress. Because of these different mechanisms used by different microorganisms, becomes an enabling environment to search for new enzymes and bioactive substances produced by these organisms can present different biotechnological applications. Among all microbial diversity, the group of actinobacteria is of great importance, because they are responsible for producing most of the known antibiotics and present as great producers of enzymes with various industrial applications. One possible application of compounds produced by this organism is the phytogenic fungi combat, such as rot caused in roots of plants by the fungus Pythium aphanidermatum. This study aimed to search actinobacteria from Caatinga biome with metabolic potential to work in the biological control of Pythium aphanidermatum fungus. With Caatinga soil samples, they were isolated actinomycetes differences in morphologies and subjected to extraction metabolites produced from solid culture medium. The extracts were tested on the P. aphanidermatum fungus diffused by drive test. From the isolation were recovered a total of 272 strains of actinomycetes, of this total 47% of the isolates showed in vitro activity against the pathogen Pythium aphanidermatum. The results showing the great potential that actinobacteria may present as control agents against root rot. However, more detailed studies are needed to prove such results

    Apolipoprotein E4 influences growth and cognitive responses to micronutrient supplementation in shantytown children from northeast Brazil

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    OBJECTIVE: Apolipoprotein E4 may benefit children during early periods of life when the body is challenged by infection and nutritional decline. We examined whether apolipoprotein E4 affects intestinal barrier function, improving short-term growth and long-term cognitive outcomes in Brazilian shantytown children. METHODS: A total of 213 Brazilian shantytown children with below-median height-for-age z-scores (HAZ) received 200,000 IU of retinol (every four months), zinc (40 mg twice weekly), or both for one year, with half of each group receiving glutamine supplementation for 10 days. Height-for-age z-scores, weight-for-age z-scores, weight-forheight z-scores, and lactulose:mannitol ratios were assessed during the initial four months of treatment. An average of four years (range 1.4-6.6) later, the children underwent cognitive testing to evaluate non-verbal intelligence, coding, verbal fluency, verbal learning, and delayed verbal learning. Apolipoprotein E4 carriage was determined by PCR analysis for 144 children. RESULTS: Thirty-seven children were apolipoprotein E4(+), with an allele frequency of 13.9%. Significant associations were found for vitamin A and glutamine with intestinal barrier function. Apolipoprotein E4(+) children receiving glutamine presented significant positive Pearson correlations between the change in height-for-age z-scores over four months and delayed verbal learning, along with correlated changes over the same period in weight-for-age z-scores and weight-for-height z-scores associated with non-verbal intelligence quotients. There was a significant correlation between vitamin A supplementation of apolipoprotein E4(+) children and improved delta lactulose/mannitol. Apolipoprotein E4(-) children, regardless of intervention, exhibited negative Pearson correlations between the change in lactulose-to-mannitol ratio over four months and verbal learning and non-verbal intelligence. CONCLUSIONS: During development, apolipoprotein E4 may function concomitantly with gut-tropic nutrients to benefit immediate nutritional status, which can translate into better long-term cognitive outcomes

    Apolipoprotein E4 influences growth and cognitive responses to micronutrient supplementation in shantytown children from northeast Brazil

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    OBJECTIVE: Apolipoprotein E4 may benefit children during early periods of life when the body is challenged by infection and nutritional decline. We examined whether apolipoprotein E4 affects intestinal barrier function, improving short-term growth and long-term cognitive outcomes in Brazilian shantytown children. METHODS: A total of 213 Brazilian shantytown children with below-median height-for-age z-scores (HAZ) received 200,000 IU of retinol (every four months), zinc (40 mg twice weekly), or both for one year, with half of each group receiving glutamine supplementation for 10 days. Height-for-age z-scores, weight-for-age z-scores, weight-forheight z-scores, and lactulose:mannitol ratios were assessed during the initial four months of treatment. An average of four years (range 1.4-6.6) later, the children underwent cognitive testing to evaluate non-verbal intelligence, coding, verbal fluency, verbal learning, and delayed verbal learning. Apolipoprotein E4 carriage was determined by PCR analysis for 144 children. RESULTS: Thirty-seven children were apolipoprotein E4(+), with an allele frequency of 13.9%. Significant associations were found for vitamin A and glutamine with intestinal barrier function. Apolipoprotein E4(+) children receiving glutamine presented significant positive Pearson correlations between the change in height-for-age z-scores over four months and delayed verbal learning, along with correlated changes over the same period in weight-for-age z-scores and weight-for-height z-scores associated with non-verbal intelligence quotients. There was a significant correlation between vitamin A supplementation of apolipoprotein E4(+) children and improved delta lactulose/mannitol. Apolipoprotein E4(-) children, regardless of intervention, exhibited negative Pearson correlations between the change in lactulose-to-mannitol ratio over four months and verbal learning and non-verbal intelligence. CONCLUSIONS: During development, apolipoprotein E4 may function concomitantly with gut-tropic nutrients to benefit immediate nutritional status, which can translate into better long-term cognitive outcomes

    Ocorrência de um surto de anel vermelho do dendê no Estado do Amazonas.

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    A cultura do dendê no Brasil é afetada por importantes doenças, com destaque para anel-vermelho (Rhadinaphelenchus cocophilus). No estado do Amazonas, os plantios de dendê são recentes, e, normalmente, estabelecidos em áreas próximas de floresta. A intensificação das práticas de poda e colheita, por ocasião do início da produção, tende a expor as plantas ao ataque do inseto vetor Rhynchophorus palmarum. Na estação experimental do CPAA, onde existe um banco de germoplasma de dendê plantado em 412ha, foi constatado recentemente um surto dessa doença. Estudos estão sendo conduzidos visando determinar a população anual do inseto vetor e os níveis de contaminação deste com os nematóides.Edição dos resumos do XXVIII Congresso Brasileiro de Fitopatologia. Resumo 421

    Lifespan extension and the doctrine of double effect

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    Recent developments in biogerontology—the study of the biology of ageing—suggest that it may eventually be possible to intervene in the human ageing process. This, in turn, offers the prospect of significantly postponing the onset of age-related diseases. The biogerontological project, however, has met with strong resistance, especially by deontologists. They consider the act of intervening in the ageing process impermissible on the grounds that it would (most probably) bring about an extended maximum lifespan—a state of affairs that they deem intrinsically bad. In a bid to convince their deontological opponents of the permissibility of this act, proponents of biogerontology invoke an argument which is grounded in the doctrine of double effect. Surprisingly, their argument, which we refer to as the ‘double effect argument’, has gone unnoticed. This article exposes and critically evaluates this ‘double effect argument’. To this end, we first review a series of excerpts from the ethical debate on biogerontology in order to substantiate the presence of double effect reasoning. Next, we attempt to determine the role that the ‘double effect argument’ is meant to fulfil within this debate. Finally, we assess whether the act of intervening in ageing actually can be justified using double effect reasoning

    Dinâmica da relação dossel:raízes de ervilhaca nativa.

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    O objetivo do trabalho foi a avaliação da dinâmica temporal do desenvolvimento do dossel e das raízes e da relação dossel:raízes de plantas de Vicia angustifolia L.Editora técnica Claudia Cristina Gulias Gomes
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