283 resultados para Farkas lemma


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Este trabalho busca identificar a maneira pela qual a cultura popular é (re)interpretada nos meios de comunicação de massa, a partir da análise dos filmes documentários produzidos pela Caravana Farkas, um projeto pioneiro de documentação de manifestações de cultura popular brasileira, realizado entre 1968 e 1970 no Nordeste. Para tanto, discute-se como os filmes se inserem no panorama político-cultural do Brasil da década de 60; quais as condições que permitiram a construção de seus discursos; que regras esses discursos estabeleceram; como e por que as manifestações culturais populares passaram a constituir objeto de estudo e de registro dos cineastas; e o que era definido por eles como cultura popular . O tema básico que perpassa os filmes é o da cultura de uma classe outra, que está no passado e não tem lugar no aqui e agora da modernidade. A alteridade e a representação do outro estão traspassadas pelas diferenças de classe, e o caráter de resistência cultural e política das manifestações de cultura popular, na visão dos cineastas, se perde na aparência de um mundo cujo destino já está traçado: é a extinção. Os filmes documentários, por outro lado, servem de lugar de confronto das diferentes culturas e de diálogo entre elas, gerando novos e múltiplos significados, que independem da vontade dos cineastas. É dessa maneira que constroem um novo discurso acerca de uma determinada realidade. Menos um reflexo, no sentido de espelhamento, mais uma referência de um tempo e um espaço que não se repetirão. Nas trilhas da cultura popular, a viagem da Caravana Farkas não chega a um termo nem a um final tranqüilo, pois é envolvida pelas contradições e incompatibilidades que as questões suscitadas pela discussão do real provocam. Mas deixa evidente que a sua importância para os estudos da Comunicação está na própria jornada e no diálogo permanente e infinito entre culturas que esse caminhar provoca.

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∗Partially supported by Grant MM409/94 Of the Ministy of Science and Education, Bulgaria. ∗∗Partially supported by Grant MM442/94 of the Ministy of Science and Education, Bulgaria.

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2000 Mathematics Subject Classification: 42B30, 46E35, 35B65.

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In questa tesi si presenta il concetto di politopo convesso e se ne forniscono alcuni esempi, poi si introducono alcuni metodi di base e risultati significativi della teoria dei politopi. In particolare si dimostra l'equivalenza tra le due definizioni di H-politopo e di V-politopo, sfruttando il metodo di eliminazione di Fourier-Motzkin per coni. Tutto ciò ha permesso di descrivere, grazie al lemma di Farkas, alcune importanti costruzioni come il cono di recessione e l'omogeneizzazione di un insieme convesso.

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The approximation lemma is a simplification of the well-known take lemma, and is used to prove properties of programs that produce lists of values. We show how the approximation lemma, unlike the take lemma, can naturally be generalised from lists to a large class of datatypes, and present a generic approximation lemma that is parametric in the datatype to which it applies. As a useful by-product, we find that generalising the approximation lemma in this way also simplifies its proof.

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This paper proposes a new approach for delay-dependent robust H-infinity stability analysis and control synthesis of uncertain systems with time-varying delay. The key features of the approach include the introduction of a new Lyapunov–Krasovskii functional, the construction of an augmented matrix with uncorrelated terms, and the employment of a tighter bounding technique. As a result, significant performance improvement is achieved in system analysis and synthesis without using either free weighting matrices or model transformation. Examples are given to demonstrate the effectiveness of the proposed approach.

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We performed an integrated genomic, transcriptomic and proteomic characterization of 373 endometrial carcinomas using array- and sequencing-based technologies. Uterine serous tumours and ∼25% of high-grade endometrioid tumours had extensive copy number alterations, few DNA methylation changes, low oestrogen receptor/progesterone receptor levels, and frequent TP53 mutations. Most endometrioid tumours had few copy number alterations or TP53 mutations, but frequent mutations in PTEN, CTNNB1, PIK3CA, ARID1A and KRAS and novel mutations in the SWI/SNF chromatin remodelling complex gene ARID5B. A subset of endometrioid tumours that we identified had a markedly increased transversion mutation frequency and newly identified hotspot mutations in POLE. Our results classified endometrial cancers into four categories: POLE ultramutated, microsatellite instability hypermutated, copy-number low, and copy-number high. Uterine serous carcinomas share genomic features with ovarian serous and basal-like breast carcinomas. We demonstrated that the genomic features of endometrial carcinomas permit a reclassification that may affect post-surgical adjuvant treatment for women with aggressive tumours.

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We discuss algorithms for combining sequential prediction strategies, a task which can be viewed as a natural generalisation of the concept of universal coding. We describe a graphical language based on Hidden Markov Models for defining prediction strategies, and we provide both existing and new models as examples. The models include efficient, parameterless models for switching between the input strategies over time, including a model for the case where switches tend to occur in clusters, and finally a new model for the scenario where the prediction strategies have a known relationship, and where jumps are typically between strongly related ones. This last model is relevant for coding time series data where parameter drift is expected. As theoretical contributions we introduce an interpolation construction that is useful in the development and analysis of new algorithms, and we establish a new sophisticated lemma for analysing the individual sequence regret of parameterised models.

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Bats are an important component of mammalian biodiversity and fill such a wide array of ecological niches that they may offer an important multisensory bioindicator role in assessing ecosystem health. There is a need to monitor population trends of bats for their own sake because many populations face numerous environmental threats related to climate change, habitat loss, fragmentation, hunting, and emerging diseases. To be able to establish bat ultrasonic biodiversity trends as a reliable indicator, it is important to standardize monitoring protocols, data management, and analyses. This chapter discusses the main issues to be considered in developing a bat ultrasonic indicator. It focuses on the results from indicator bats program (iBats), a system for the global acoustic monitoring of bats, in Eastern Europe. Finally, the chapter reviews the strengths and weaknesses of the Program and considers the opportunities and threats that it may face in the future.

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This thesis provides new knowledge on an understudied group of grasses, some of which are resurrection grasses (i.e. able to withstand extreme drought). The sole Australian species (Tripogon loliiformis) is morphologically diverse and could be more than one species. This study sought to determine how many species of Tripogon occur in Australia, their relationships to other species in the genus and to two other genera of resurrection grasses (Eragrostiella and Oropetium). Results of the research indicate there is not enough evidence, from DNA sequence data, to warrant splitting up T. loliiformis into multiple species. The extensive morphological diversity seems to be influenced by environmental conditions. The three genera are so closely related that they could be grouped into a single genus. This new knowledge opens up pathways for future investigations, including studying genes responsible for desiccation tolerance and the conservation of native grasses that occur in rocky habitats.

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In two fMRI experiments, participants named pictures with superimposed distractors that were high or low in frequency or varied in terms of age of acquisition. Pictures superimposed with low-frequency words were named more slowly than those superimposed with high-frequency words, and late-acquired words interfered with picture naming to a greater extent than early-acquired words. The distractor frequency effect (Experiment 1) was associated with increased activity in left premotor and posterior superior temporal cortices, consistent with the operation of an articulatory response buffer and verbal selfmonitoring system. Conversely, the distractor age-of-acquisition effect (Experiment 2) was associated with increased activity in the left middle and posterior middle temporal cortex, consistent with the operation of lexical level processes such as lemma and phonological word form retrieval. The spatially dissociated patterns of activity across the two experiments indicate that distractor effects in picture-word interference may occur at lexical or postlexical levels of processing in speech production.

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A toxic effect of a,a-trehalose in an angiospermic plant, Cuscuta reflexa (dodder), Is described. This disaccharide and Its analogs, 2-aminotrehalose and 4-aminotbhakose, induced a raid blackening of the terminal region of the vine which is Involved in elongation growth. From the results of in vitro growth of several angkiopermic plants and determination of trehalase activity in them, it is concluded that the toxic effect of trehalose in Cucaa is because of the very low trehalas activity In the vine. As a result, trehalose accumulates In the vine and interferes with some process closely associated with growth. The growth potential of Lemma (a duckweed) in a medium containing trehalose as the carbon source was ihreversibly lost upon addition of trealosamine, an Inhibitor of trehalase activity. It is concluded that, if allowed to accumulate within the tissue, trehalose may be potentiaMly toxic or inhibitory to higher plants in generaL The presence of trhalase actvity in plants, where Its substrate has not been found to occur, is envisged to relieve the plant from the toxic effects of trehalose which it may encounter in soil or during association with fungi or insects.

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A direct and simple approach, utilizing Watson's lemma, is presented for obtaining an approximate solution of a three-part Wiener-Hopf problem associated with the problem of diffraction of a plane wave by a soft strip.

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In this paper, the trajectory tracking control of an autonomous underwater vehicle (AUVs) in six-degrees-of-freedom (6-DOFs) is addressed. It is assumed that the system parameters are unknown and the vehicle is underactuated. An adaptive controller is proposed, based on Lyapunov׳s direct method and the back-stepping technique, which interestingly guarantees robustness against parameter uncertainties. The desired trajectory can be any sufficiently smooth bounded curve parameterized by time even if consist of straight line. In contrast with the majority of research in this field, the likelihood of actuators׳ saturation is considered and another adaptive controller is designed to overcome this problem, in which control signals are bounded using saturation functions. The nonlinear adaptive control scheme yields asymptotic convergence of the vehicle to the reference trajectory, in the presence of parametric uncertainties. The stability of the presented control laws is proved in the sense of Lyapunov theory and Barbalat׳s lemma. Efficiency of presented controller using saturation functions is verified through comparing numerical simulations of both controllers.

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A typical barley (Hordeum vulgare) floret consists of reproductive organs three stamens and a pistil, and non-reproductive organs-lodicules and two floral bracts, abaxial called 'lemma' and adaxial 'palea'. The floret is subtended by two additional bracts called outer or empty glumes. Together these organs form the basic structural unit of the grass inflorescence, a spikelet. There are commonly three spikelets at each rachis (floral stem of the barley spike) node, one central and two lateral spikelets. Rare naturally occurring or induced phenotypic variants that contain a third bract subtending the central spikelets have been described in barley. The gene responsible for this phenotype was called the THIRD OUTER GLUME1 (Trd1). The Trd1 mutants fail to suppress bract growth and as a result produce leaf-like structures that subtend each rachis node in the basal portion of the spike. Also, floral development at the collar is not always suppressed. In rice and maize, recessive mutations in NECK LEAF1 (Nl1) and TASSEL SHEATH1 (Tsh1) genes, respectively, have been shown to be responsible for orthologous phenotypes. Fine mapping of the trd1 phenotype in an F-3 recombinant population enabled us to position on the long arm of chromosome 1H to a 10 cM region. We anchored this to a conserved syntenic region on rice chromosome Os05 and selected a set of candidate genes for validation by resequencing PCR amplicons from a series of independent mutant alleles. This analysis revealed that a GATA transcription factor, recently proposed to be Trd1, contained mutations in 10 out of 14 independent trd1 mutant alleles that would generate non-functional TRD1 proteins. Together with genetic linkage data, we confirm the identity of Trd1 as the GATA transcription factor ortholog of rice Nl1 and maize Tsh1 genes.