960 resultados para Gibbs phenomenon


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Com o objetivo de verificar a existência da interação genótipo x ambiente, sob a forma de heterogeneidade de variâncias para a produção de leite na espécie bubalina e o seu impacto na avaliação genética dos animais, utilizando a inferência Bayesiana por meio de Amostrador de Gibbs, foram utilizados 5.484 registros de produção de leite referentes à produções de 2.994 búfalas predominantemente Murrah, filhas de 150 reprodutores, acasalados com 1130 matrizes, cujos partos ocorreram entre os anos de 1974 e 2004. Os registros foram provenientes do Programa de Melhoramento Genético dos Bubalinos (PROMEBUL) com a adição de registros provenientes do rebanho da EMBRAPA Amazônia Oriental -EAO, localizada em Belém, Pará. Foram estabelecidas classes de rebanho-ano de parto e de acordo com o desvio padrão de cada classe, os registros de produção de leite foram classificados em classes de alto e baixo desvio-padrão fenotípico. Posteriormente, os dados foram analisados desconsiderando e considerando as classes de desvio-padrão. O modelo utilizado empregou os efeitos fixos referentes às classes de rebanho-ano, mês de parto e covariáveis idade da fêmea ao parto e duração da lactação, além do efeito aleatório de animal, ambiente permanente e ambiente temporário. Para os efeitos fixos, foi assumido distribuição à priori uniforme e para os componentes de (co)variâncias foram assumidas distribuições priori qui-quadrado inversa e Wishart invertida. As médias observadas e desvio-padrão para produção de leite nas classes de alto e baixo desvio-padrão e em análise geral, foram iguais a 1870,21±758,78, 1900,50±587,76 e 1885,48±677,98, respectivamente. As médias posteriores para os componentes de variâncias foram maiores na classe de alto desvio-padrão. A herdabilidade obtida na classe de alto desvio-padrão foi próxima do valor observado na análise geral e inferior ao valor encontrado na classe de baixo desvio-padrão fenotípico. A correlação genética para produção de leite entre as classes de desvio-padrão foi igual a 0,58. As correlações de Spearman entre os valores genéticos para a produção de leite obtidos em análise geral com os valores obtidos nas classes de alto e baixo desvio padrão foram iguais a 0,94 e 0,93, respectivamente, para todos os reprodutores. Para uma amostra dos 10 melhores reprodutores, as mesmas correlações foram iguais a 0,94 e 0,47, respectivamente. Tais resultados revelam presença de heterogeneidade de variâncias entre rebanhos e esta heterogeneidade de variâncias é resultante de fatores ambientais, que podem levar a uma classificação errônea dos melhores reprodutores geneticamente para a produção leite.

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Let T : M → M be a smooth involution on a closed smooth manifold and F = n j=0 F j the fixed point set of T, where F j denotes the union of those components of F having dimension j and thus n is the dimension of the component of F of largest dimension. In this paper we prove the following result, which characterizes a small codimension phenomenon: suppose that n ≥ 4 is even and F has one of the following forms: 1) F = F n ∪ F 3 ∪ F 2 ∪ {point}; 2) F = F n ∪ F 3 ∪ F 2 ; 3) F = F n ∪ F 3 ∪ {point}; or 4) F = F n ∪ F 3 . Also, suppose that the normal bundles of F n, F 3 and F 2 in M do not bound. If k denote the codimension of F n, then k ≤ 4. Further, we construct involutions showing that this bound is best possible in the cases 2) and 4), and in the cases 1) and 3) when n is of the form n = 4t, with t ≥ 1.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Results of the analysis of dynamic behavior of flashover phenomenon on the high voltage-polluted insulators are presented. These results were taken from a mathematical and an experimental model that introduce the variable thickness influence of the layer pollution deposited on the high-voltage insulator surface. Analysis of the flashover was done by way of introducing a variation in the thickness of the channel of Obenaus' model, simulating a layer pollution of variable thickness. The objective was to obtain a better reproduction of the real layer pollution deposited on the insulator that works in the polluted regions. Two types of thickness variations were used: a sudden variation, using a step; and a soft variation, using a ramp; that were put along the way of the discharge. Comparison between the mathematical and experimental models showed that introduction of a ramp makes Obenaus' model more efficient in analyzing behavior of flashover phenomenon.

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An experimental study on drag-reduction phenomenon in dispersed oil-water flow has been performed in a 26-mm-i.d. Twelve meter long horizontal glass pipe. The flow was characterized using a novel wire-mesh sensor based on capacitance measurements and high-speed video recording. New two-phase pressure gradient, volume fraction, and phase distribution data have been used in the analysis. Drag reduction and slip ratio were detected at oil volume fractions between 10 and 45% and high mixture Reynolds numbers, and with water as the dominant phase. Phase-fraction distribution diagrams and cross-sectional imaging of the flow suggested the presence of a higher amount of water near to the pipe wall. Based on that, a phenomenology for explaining drag reduction in dispersed flow in a flow situation where slip ratio is significant is proposed. A simple phenomenological model is developed and the agreement between model predictions and data, including data from the literature, is encouraging. (c) 2011 American Institute of Chemical Engineers AIChE J, 2012

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Abstract Background Assuming a higher risk of latent tuberculosis (TB) infection in the population of Rio de Janeiro, Brazil, in October of 1998 the TB Control Program of Clementino Fraga Filho Hospital (CFFH) routinely started to recommend a two-step tuberculin skin test (TST) in contacts of pulmonary TB cases in order to distinguish a boosting reaction due to a recall of delayed hypersensitivity previously established by infection with Mycobacterium tuberculosis (M.tb) or BCG vaccination from a tuberculin conversion. The aim of this study was to assess the prevalence of boosted tuberculin skin tests among contacts of individuals with active pulmonary tuberculosis (TB). Methods Retrospective cohort of TB contacts ≥ 12 years old who were evaluated between October 1st, 1998 and October 31st 2001. Contacts with an initial TST ≤ 4 mm were considered negative and had a second TST applied after 7–14 days. Boosting reaction was defined as a second TST ≥ 10 mm with an increase in induration ≥ 6 mm related to the first TST. All contacts with either a positive initial or repeat TST had a chest x-ray to rule out active TB disease, and initially positive contacts were offered isoniazid preventive therapy. Contacts that boosted did not receive treatment for latent TB infection and were followed for 24 months to monitor the development of TB. Statistical analysis of dichotomous variables was performed using Chi-square test. Differences were considered significant at a p < 0.05. Results Fifty four percent (572/1060) of contacts had an initial negative TST and 79% of them (455/572) had a second TST. Boosting was identified in 6% (28/455). The mean age of contacts with a boosting reaction was 42.3 ± 21.1 and with no boosting was 28.7 ± 21.7 (p = 0.01). Fifty percent (14/28) of individuals whose test boosted met criteria for TST conversion on the second TST (increase in induration ≥ 10 mm). None of the 28 contacts whose reaction boosted developed TB disease within two years following the TST. Conclusion The low number of contacts with boosting and the difficulty in distinguishing boosting from TST conversion in the second TST suggests that the strategy of two-step TST testing among contacts of active TB cases may not be useful. However, this conclusion must be taken with caution because of the small number of subjects followed.

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Introduction 1.1 Occurrence of polycyclic aromatic hydrocarbons (PAH) in the environment Worldwide industrial and agricultural developments have released a large number of natural and synthetic hazardous compounds into the environment due to careless waste disposal, illegal waste dumping and accidental spills. As a result, there are numerous sites in the world that require cleanup of soils and groundwater. Polycyclic aromatic hydrocarbons (PAHs) are one of the major groups of these contaminants (Da Silva et al., 2003). PAHs constitute a diverse class of organic compounds consisting of two or more aromatic rings with various structural configurations (Prabhu and Phale, 2003). Being a derivative of benzene, PAHs are thermodynamically stable. In addition, these chemicals tend to adhere to particle surfaces, such as soils, because of their low water solubility and strong hydrophobicity, and this results in greater persistence under natural conditions. This persistence coupled with their potential carcinogenicity makes PAHs problematic environmental contaminants (Cerniglia, 1992; Sutherland, 1992). PAHs are widely found in high concentrations at many industrial sites, particularly those associated with petroleum, gas production and wood preserving industries (Wilson and Jones, 1993). 1.2 Remediation technologies Conventional techniques used for the remediation of soil polluted with organic contaminants include excavation of the contaminated soil and disposal to a landfill or capping - containment - of the contaminated areas of a site. These methods have some drawbacks. The first method simply moves the contamination elsewhere and may create significant risks in the excavation, handling and transport of hazardous material. Additionally, it is very difficult and increasingly expensive to find new landfill sites for the final disposal of the material. The cap and containment method is only an interim solution since the contamination remains on site, requiring monitoring and maintenance of the isolation barriers long into the future, with all the associated costs and potential liability. A better approach than these traditional methods is to completely destroy the pollutants, if possible, or transform them into harmless substances. Some technologies that have been used are high-temperature incineration and various types of chemical decomposition (for example, base-catalyzed dechlorination, UV oxidation). However, these methods have significant disadvantages, principally their technological complexity, high cost , and the lack of public acceptance. Bioremediation, on the contrast, is a promising option for the complete removal and destruction of contaminants. 1.3 Bioremediation of PAH contaminated soil & groundwater Bioremediation is the use of living organisms, primarily microorganisms, to degrade or detoxify hazardous wastes into harmless substances such as carbon dioxide, water and cell biomass Most PAHs are biodegradable unter natural conditions (Da Silva et al., 2003; Meysami and Baheri, 2003) and bioremediation for cleanup of PAH wastes has been extensively studied at both laboratory and commercial levels- It has been implemented at a number of contaminated sites, including the cleanup of the Exxon Valdez oil spill in Prince William Sound, Alaska in 1989, the Mega Borg spill off the Texas coast in 1990 and the Burgan Oil Field, Kuwait in 1994 (Purwaningsih, 2002). Different strategies for PAH bioremediation, such as in situ , ex situ or on site bioremediation were developed in recent years. In situ bioremediation is a technique that is applied to soil and groundwater at the site without removing the contaminated soil or groundwater, based on the provision of optimum conditions for microbiological contaminant breakdown.. Ex situ bioremediation of PAHs, on the other hand, is a technique applied to soil and groundwater which has been removed from the site via excavation (soil) or pumping (water). Hazardous contaminants are converted in controlled bioreactors into harmless compounds in an efficient manner. 1.4 Bioavailability of PAH in the subsurface Frequently, PAH contamination in the environment is occurs as contaminants that are sorbed onto soilparticles rather than in phase (NAPL, non aqueous phase liquids). It is known that the biodegradation rate of most PAHs sorbed onto soil is far lower than rates measured in solution cultures of microorganisms with pure solid pollutants (Alexander and Scow, 1989; Hamaker, 1972). It is generally believed that only that fraction of PAHs dissolved in the solution can be metabolized by microorganisms in soil. The amount of contaminant that can be readily taken up and degraded by microorganisms is defined as bioavailability (Bosma et al., 1997; Maier, 2000). Two phenomena have been suggested to cause the low bioavailability of PAHs in soil (Danielsson, 2000). The first one is strong adsorption of the contaminants to the soil constituents which then leads to very slow release rates of contaminants to the aqueous phase. Sorption is often well correlated with soil organic matter content (Means, 1980) and significantly reduces biodegradation (Manilal and Alexander, 1991). The second phenomenon is slow mass transfer of pollutants, such as pore diffusion in the soil aggregates or diffusion in the organic matter in the soil. The complex set of these physical, chemical and biological processes is schematically illustrated in Figure 1. As shown in Figure 1, biodegradation processes are taking place in the soil solution while diffusion processes occur in the narrow pores in and between soil aggregates (Danielsson, 2000). Seemingly contradictory studies can be found in the literature that indicate the rate and final extent of metabolism may be either lower or higher for sorbed PAHs by soil than those for pure PAHs (Van Loosdrecht et al., 1990). These contrasting results demonstrate that the bioavailability of organic contaminants sorbed onto soil is far from being well understood. Besides bioavailability, there are several other factors influencing the rate and extent of biodegradation of PAHs in soil including microbial population characteristics, physical and chemical properties of PAHs and environmental factors (temperature, moisture, pH, degree of contamination). Figure 1: Schematic diagram showing possible rate-limiting processes during bioremediation of hydrophobic organic contaminants in a contaminated soil-water system (not to scale) (Danielsson, 2000). 1.5 Increasing the bioavailability of PAH in soil Attempts to improve the biodegradation of PAHs in soil by increasing their bioavailability include the use of surfactants , solvents or solubility enhancers.. However, introduction of synthetic surfactant may result in the addition of one more pollutant. (Wang and Brusseau, 1993).A study conducted by Mulder et al. showed that the introduction of hydropropyl-ß-cyclodextrin (HPCD), a well-known PAH solubility enhancer, significantly increased the solubilization of PAHs although it did not improve the biodegradation rate of PAHs (Mulder et al., 1998), indicating that further research is required in order to develop a feasible and efficient remediation method. Enhancing the extent of PAHs mass transfer from the soil phase to the liquid might prove an efficient and environmentally low-risk alternative way of addressing the problem of slow PAH biodegradation in soil.

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The present study aims at analyzing how dark humour as a cinematic genre travels cross-culturally through a specific mode of audiovisual translation, i.e. dubbing. In particular, it takes into consideration the processes involved in dubbing humour from English into Italian as observed in the English- and Italian-language versions of ten British and American dark comedies from the 1940s to the 2000s. In an attempt to identify some of the main mechanisms of the dark humour genre, the humorous content of the films was analyzed in terms of the elements on which specific scenes are based, mainly the non-verbal and verbal components. In the cases in which verbal elements were involved, i.e. the examples of verbally expressed humour, the analysis was concerned with whether they were adapted into Italian and to what effect. Quantification of the different kinds of dark humour revealed that in the sample of dark comedies verbal dark humour had a higher frequency (85.3%) than non-verbal dark humour (14.7%), which partially disconfirmed the first part of the research hypothesis. However, the significance of contextual elements in the conveying of dark humour, both in the form of Nsp VEH (54.31%) and V-V (V+VE) (21.68%), provided support for the hypothesis that, even when expressed verbally, dark humour is more closely linked to context-based rather than purely linguistic humour (4.9%). The second part of the analysis was concerned with an investigation of the strategies adopted for the translation of verbal dark humour elements from the SL (English) into the TL (Italian) through the filter of dubbing. Four translational strategies were identified as far as the rendering of verbal dark humour is concerned: i) complete omission; ii) weakening; iii) close rendering; and iv) increased effect. Complete omission was found to be the most common among these strategies, with 80.9% of dark humour examples being transposed in a way that kept the ST’s function substantially intact. Weakening of darkly humorous lines was applied in 12% of cases, whereas increased effect accounted for 4.6% and complete omission for 2.5%. The fact that for most examples of Nsp VEH (84.9%) and V-AC (V+VE) (91.4%) a close rendering effect was observed and that 12 out of 21 examples of V-AC (PL) (a combined 57%) were either omitted or weakened seemed to confirm, on the one hand, the complexity of the translation process required by cases of V-AC (PL) and V-AC (CS). On the other hand, as suggested in the second part of the research hypothesis, the data might be interpreted as indicating that lesser effort on the translator/adaptor’s part is involved in the adaptation of V-AC (Nsp VEH) and V-V (V+VE). The issue of the possible censorial intervention undergone by examples of verbal dark humour in the sample still remains unclear.

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Questa trattazione si propone di fornire una spiegazione del fenomeno di Gibbs in termini matematici. Con l'espressione fenomeno di Gibbs intendiamo la presenza di forti oscillazioni nei polinomi di Fourier di una funzione con discontinuità di prima specie. Si osserva che queste anomalie, presenti vicino ai punti di discontinuità, non sembrano diminuire aumentando il grado del polinomio, al punto che la serie pare non convergere alla funzione sviluppata. Osserveremo che utilizzando un altro tipo di polinomi trigonometrici, quelli di Fejér in luogo di quelli di Fourier, scomparirà il fenomeno di Gibbs. Nonostante ciò, spesso si preferisce rappresentare una funzione utilizzando il suo polinomio di Fourier poiché questo è il polinomio trigonometrico che meglio approssima la funzione in norma quadratica.

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I present a new experimental method called Total Internal Reflection Fluorescence Cross-Correlation Spectroscopy (TIR-FCCS). It is a method that can probe hydrodynamic flows near solid surfaces, on length scales of tens of nanometres. Fluorescent tracers flowing with the liquid are excited by evanescent light, produced by epi-illumination through the periphery of a high NA oil-immersion objective. Due to the fast decay of the evanescent wave, fluorescence only occurs for tracers in the ~100 nm proximity of the surface, thus resulting in very high normal resolution. The time-resolved fluorescence intensity signals from two laterally shifted (in flow direction) observation volumes, created by two confocal pinholes are independently measured and recorded. The cross-correlation of these signals provides important information for the tracers’ motion and thus their flow velocity. Due to the high sensitivity of the method, fluorescent species with different size, down to single dye molecules can be used as tracers. The aim of my work was to build an experimental setup for TIR-FCCS and use it to experimentally measure the shear rate and slip length of water flowing on hydrophilic and hydrophobic surfaces. However, in order to extract these parameters from the measured correlation curves a quantitative data analysis is needed. This is not straightforward task due to the complexity of the problem, which makes the derivation of analytical expressions for the correlation functions needed to fit the experimental data, impossible. Therefore in order to process and interpret the experimental results I also describe a new numerical method of data analysis of the acquired auto- and cross-correlation curves – Brownian Dynamics techniques are used to produce simulated auto- and cross-correlation functions and to fit the corresponding experimental data. I show how to combine detailed and fairly realistic theoretical modelling of the phenomena with accurate measurements of the correlation functions, in order to establish a fully quantitative method to retrieve the flow properties from the experiments. An importance-sampling Monte Carlo procedure is employed in order to fit the experiments. This provides the optimum parameter values together with their statistical error bars. The approach is well suited for both modern desktop PC machines and massively parallel computers. The latter allows making the data analysis within short computing times. I applied this method to study flow of aqueous electrolyte solution near smooth hydrophilic and hydrophobic surfaces. Generally on hydrophilic surface slip is not expected, while on hydrophobic surface some slippage may exists. Our results show that on both hydrophilic and moderately hydrophobic (contact angle ~85°) surfaces the slip length is ~10-15nm or lower, and within the limitations of the experiments and the model, indistinguishable from zero.

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Nella tesi ho trattato l'effetto Gibbs,ovvero la presenza di forti oscillazioni nei polinomi di Fourier di funzioni con discontinuità di prima specie. Infine ho introdotto le somme di Fejér osservando come con questi polinomi trigonometrici si possa eliminare l'effetto Gibbs.

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Nowadays the environmental issues and the climatic change play fundamental roles in the design of urban spaces. Our cities are growing in size, many times only following immediate needs without a long-term vision. Consequently, the sustainable development has become not only an ethical but also a strategic need: we can no longer afford an uncontrolled urban expansion. One serious effect of the territory industrialisation process is the increase of urban air and surfaces temperatures compared to the outlying rural surroundings. This difference in temperature is what constitutes an urban heat island (UHI). The purpose of this study is to provide a clarification on the role of urban surfacing materials in the thermal dynamics of an urban space, resulting in useful indications and advices in mitigating UHI. With this aim, 4 coloured concrete bricks were tested, measuring their emissivity and building up their heat release curves using infrared thermography. Two emissivity evaluation procedures were carried out and subsequently put in comparison. Samples performances were assessed, and the influence of the colour on the thermal behaviour was investigated. In addition, some external pavements were analysed. Albedo and emissivity parameters were evaluated in order to understand their thermal behaviour in different conditions. Surfaces temperatures were recorded in a one-day measurements campaign. ENVI-met software was used to simulate how the tested materials would behave in two typical urban scenarios: a urban canyon and a urban heat basin. Improvements they can carry to the urban microclimate were investigated. Emissivities obtained for the bricks ranged between 0.92 and 0.97, suggesting a limited influence of the colour on this parameter. Nonetheless, white concrete brick showed the best thermal performance, whilst the black one the worst; red and yellow ones performed pretty identical intermediate trends. De facto, colours affected the overall thermal behaviour. Emissivity parameter was measured in the outdoor work, getting (as expected) high values for the asphalts. Albedo measurements, conducted with a sunshine pyranometer, proved the improving effect given by the yellow paint in terms of solar reflection, and the bad influence of haze on the measurement accuracy. ENVI-met simulations gave a demonstration on the effectiveness in thermal improving of some tested materials. In particular, results showed good performances for white bricks and granite in the heat basin scenario, and painted concrete and macadam in the urban canyon scenario. These materials can be considered valuable solutions in UHI mitigation.

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In questa tesi studiamo l'effetto Gibbs. Tale fenomeno si manifesta tramite la presenza di sovra-oscillazioni nei polinomi di Fourier di funzioni che presentano discontinuità di prima specie. La differenza tra il massimo ed il minimo del polinomio di Fourier di tali funzioni, in prossimità di un punto di discontinuità della funzione, è strettamente maggiore del salto della funzione in quel punto, anche per n che tende all'infinito. Per attenuare le sovra-oscillazioni delle somme parziali di Fourier si utilizzano le serie di Fejer e si vede come effettivamente il fenomeno di Gibbs scompaia.

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Energy in a multipartite quantum system appears from an operational perspective to be distributed to some extent non-locally because of correlations extant among the system's components. This non-locality allows users to transfer, in effect, locally accessible energy between sites of different system components by local operations and classical communication (LOCC). Quantum energy teleportation is a three-step LOCC protocol, accomplished without an external energy carrier, for effectively transferring energy between two physically separated, but correlated, sites. We apply this LOCC teleportation protocol to a model Heisenberg spin particle pair initially in a quantum thermal Gibbs state, making temperature an explicit parameter. We find in this setting that energy teleportation is possible at any temperature, even at temperatures above the threshold where the particles' entanglement vanishes. This shows for Gibbs spin states that entanglement is not fundamentally necessary for energy teleportation; correlation other than entanglement can suffice. Dissonance-quantum correlation in separable states-is in this regard shown to be a quantum resource for energy teleportation, more dissonance being consistently associated with greater energy yield. We compare energy teleportation from particle A to B in Gibbs states with direct local energy extraction by a general quantum operation on B and find a temperature threshold below which energy extraction by a local operation is impossible. This threshold delineates essentially two regimes: a high temperature regime where entanglement vanishes and the teleportation generated by other quantum correlations yields only vanishingly little energy relative to local extraction and a second low-temperature teleportation regime where energy is available at B only by teleportation.