8,316 research outputs found

    Multifractal Properties of Aperiodic Ising Model: role of geometric fluctuations

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    The role of the geometric fluctuations on the multifractal properties of the local magnetization of aperiodic ferromagnetic Ising models on hierachical lattices is investigated. The geometric fluctuations are introduced by generalized Fibonacci sequences. The local magnetization is evaluated via an exact recurrent procedure encompassing a real space renormalization group decimation. The symmetries of the local magnetization patterns induced by the aperiodic couplings is found to be strongly (weakly) different, with respect to the ones of the corresponding homogeneous systems, when the geometric fluctuations are relevant (irrelevant) to change the critical properties of the system. At the criticality, the measure defined by the local magnetization is found to exhibit a non-trivial F(alpha) spectra being shifted to higher values of alpha when relevant geometric fluctuations are considered. The critical exponents are found to be related with some special points of the F(alpha) function and agree with previous results obtained by the quite distinct transfer matrix approach.Comment: 10 pages, 7 figures, 3 Tables, 17 reference

    Assessing the Prosody of Non-Native Speakers of English: Measures and Feature Sets

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    In this paper, we describe a new database with audio recordings of non-native (L2) speakers of English, and the perceptual evaluation experiment conducted with native English speakers for assessing the prosody of each recording. These annotations are then used to compute the gold standard using different methods, and a series of regression experiments is conducted to evaluate their impact on the performance of a regression model predicting the degree of Abstract naturalness of L2 speech. Further, we compare the relevance of different feature groups modelling prosody in general (without speech tempo), speech rate and pauses modelling speech tempo (fluency), voice quality, and a variety of spectral features. We also discuss the impact of various fusion strategies on performance.Overall, our results demonstrate that the prosody of non-native speakers of English as L2 can be reliably assessed using supra- segmental audio features; prosodic features seem to be the most important ones

    The ICL-TUM-PASSAU approach for the MediaEval 2015 "affective impact of movies" task

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    In this paper we describe the Imperial College London, Technische Universitat München and University of Passau (ICL+TUM+PASSAU) team approach to the MediaEval's "Affective Impact of Movies" challenge, which consists in the automatic detection of affective (arousal and valence) and violent content in movie excerpts. In addition to the baseline features, we computed spectral and energy related acoustic features, and the probability of various objects being present in the video. Random Forests, AdaBoost and Support Vector Machines were used as classification methods. Best results show that the dataset is highly challenging for both affect and violence detection tasks, mainly because of issues in inter-rater agreement and data scarcity

    Ciclo reprodutivo de machos e fêmeas de jacaré-do-Pantanal, Caiman crocodilus yacare.

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    A reprodução dos crocodilianos, tanto em condições naturais como em cativeiro, tem recebido considerável atenção, particularmente devido a suas aplicações no manejo. entretanto, muitas das informações disponíveis são relacionadas à produção de ninhos, duração do período de postura, tamanho de ovos e filhotes e sua relação com tamanho das fêmeas (Greer, 1975; Thorbjarnarson, 1994, 1996; Campos & Magnusson, 1995). Além dos estudos com aligátores (por ex. Joanen & McNease, 1980; lance, 1987, 1989; Guillette & Milnes, 2000; Uribe & Guillette, 2000), e uns poucos trabalhos com outras espécies como Crocodylus niloticus (Graham, 1968; Kofron, 1990) ou Caiman crocodilus (Thorbjarnarson, 1994), existem poucas informações sobre a estrutura e função das gônadas dos crodilianos. Nas espécies estudadas, nas atividades das gônadas têm mostrado um ciclo sazonas, relacionado com os fatores ambientais, como temperatura e nível d'água. A produção de hormônios pode variar entre espécies e sua relação com a espermatogênese pode não ser consistente, entretanto, o desenvolvimento folicular e ovidutal parecem ser associados com os hormônios sexuais esteróides (Lance, 1987; Kofron, 1990; Guillette & Milnes, 2000). A biologia reprodutiva do jacaré-do-Pantanal, Caiman crocodilus yacare, foi estudado por vários autores (Crasharw e Shaller, 1980; Cintra, 1988; Campos, 1993, Campos & Magnusson, 1995; Aleixo & Maciel, 1998), no entanto, não existem estudos da função endócrina das gônadas dos machos e fêmeas. Este Comunicado Técnico tem o objetivo de preencher essa lacuna dos conhecimentos da vitologênese e espermatogênese do jacaré-do-Pantanal.bitstream/item/79546/1/COT51.pd

    Generalized local interactions in 1D: solutions of quantum many-body systems describing distinguishable particles

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    As is well-known, there exists a four parameter family of local interactions in 1D. We interpret these parameters as coupling constants of delta-type interactions which include different kinds of momentum dependent terms, and we determine all cases leading to many-body systems of distinguishable particles which are exactly solvable by the coordinate Bethe Ansatz. We find two such families of systems, one with two independent coupling constants deforming the well-known delta interaction model to non-identical particles, and the other with a particular one-parameter combination of the delta- and (so-called) delta-prime interaction. We also find that the model of non-identical particles gives rise to a somewhat unusual solution of the Yang-Baxter relations. For the other model we write down explicit formulas for all eigenfunctions.Comment: 23 pages v2: references adde

    Dinâmica da cobertura do solo brasileiro: projeto trees 3

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    Este trabalho trata da validação das classificações realizadas para o território brasileiro nos anos de 1990 e 2000 pelo projeto Global Monitoring (TREES-3), uma parceria entre a Organização das Nações Unidas para Agricultura e Alimentação (FAO) e o Joint Research Centre (JRC). O objetivo foi estimar a dinâmica da cobertura vegetal nas áreas de interesse no período de 1990 a 2000. Um total de 708 amostras de imagens Landsat com 400 km2 de área cada passou pelos processos de segmentação e classificação supervisionada. A validação foi feita visualmente com o auxílio do Google Earth e teve como resultado 16% de mudança da cobertura vegetal florestal para outro tipo de cobertura (other land cover) nas áreas já validadas, que são Amazônia, Cerrado e Maranhão. No Pampa houve um aumento de 2% de cobertura florestal, devido à crescente prática de plantio de florestas homogêneas, que consiste na plantação de pinus e eucalipto para exploração madeireira

    Zoneamento edáfoclimático da olivicultura para o Rio Grande do Sul.

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    Introdução; Material e métodos; Resultados e Discussão; Conclusões; Agradecimentos; Referências

    Zoneamento edafoclimático da olivicultura para o Rio Grande do Sul.

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    Introdução; Material e métodos; Resultados e Discussão; Conclusões; Agradecimentos; Referências

    Controlling a resonant transmission across the δ\delta'-potential: the inverse problem

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    Recently, the non-zero transmission of a quantum particle through the one-dimensional singular potential given in the form of the derivative of Dirac's delta function, λδ(x)\lambda \delta'(x) , with λR\lambda \in \R, being a potential strength constant, has been discussed by several authors. The transmission occurs at certain discrete values of λ\lambda forming a resonance set λnn=1{\lambda_n}_{n=1}^\infty. For λλnn=1\lambda \notin {\lambda_n}_{n=1}^\infty this potential has been shown to be a perfectly reflecting wall. However, this resonant transmission takes place only in the case when the regularization of the distribution δ(x)\delta'(x) is constructed in a specific way. Otherwise, the δ\delta'-potential is fully non-transparent. Moreover, when the transmission is non-zero, the structure of a resonant set depends on a regularizing sequence Δε(x)\Delta'_\varepsilon(x) that tends to δ(x)\delta'(x) in the sense of distributions as ε0\varepsilon \to 0. Therefore, from a practical point of view, it would be interesting to have an inverse solution, i.e. for a given λˉR\bar{\lambda} \in \R to construct such a regularizing sequence Δε(x)\Delta'_\varepsilon(x) that the δ\delta'-potential at this value is transparent. If such a procedure is possible, then this value λˉ\bar{\lambda} has to belong to a corresponding resonance set. The present paper is devoted to solving this problem and, as a result, the family of regularizing sequences is constructed by tuning adjustable parameters in the equations that provide a resonance transmission across the δ\delta'-potential.Comment: 21 pages, 4 figures. Corrections to the published version added; http://iopscience.iop.org/1751-8121/44/37/37530
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