Biometria, grau de umidade e número de sementes/Kg da espécie Euxylophora paraensis (Pau-amarelo).

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The compound Poisson limit ruling periodic extreme behaviour of non-uniformly hyperbolic dynamics

We prove that the distributional limit of the normalised number of returns to small neighbourhoods of periodic points of non-uniformly hyperbolic dynamical systems is compound Poisson. The returns to small balls around a fixed point in the phase space correspond to the occurrence of rare events, or exceedances of high thresholds, so that there is a connection between the laws of Return Times Statistics and Extreme Value Laws. The fact that the fixed point in the phase space is a repelling periodic point implies that there is a tendency for the exceedances to appear in clusters whose average sizes is given by the Extremal Index, which depends on the expansion of the system at the periodic point. We recall that for generic points, the exceedances, in the limit, are singular and occur at Poisson times. However, around periodic points, the picture is different: the respective point processes of exceedances converge to a compound Poisson process, so instead of single exceedances, we have entire clusters of exceedances occurring at Poisson times with a geometric distribution ruling its multiplicity. The systems to which our results apply include: general piecewise expanding maps of the interval (Rychlik maps), maps with indifferent fixed points (Manneville-Pomeau maps) and Benedicks-Carleson quadratic maps.Comment: To appear in Communications in Mathematical Physic

Germinação de sementes de Aspidosperma spruceanum Benth ex Mull. Arg. (Araracanga).

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Visser's Massive Gravity Bimetric Theory Revisited

A massive gravity theory was proposed by Visser in the late nineties. This theory, based on a backgroung metric $b_{\alpha \beta}$ and on an usual dynamical metric $g_{\alpha \beta}$ has the advantage of being free of ghosts as well as discontinuities present in other massive theories proposed in the past. In the present investigation, the equations of Visser's theory are revisited with a particular care on the related conservation laws.\ It will be shown that a multiplicative factor is missing in the graviton tensor originally derived by Visser, which has no incidence on the weak field approach but becomes important in the strong field regime when, for instance, cosmological applications are considered. In this case, contrary to some previous claims found in the literature, we conclude that a non-static background metric is required in order to obtain a solution able to mimic the $\Lambda$CDM cosmology.Comment: 10 pages - Accepted for publication in Physical Review

Post-partum anoestrus in Anglo-Nubian and Saanen goats raised in semi-arid of North-eastern Brazil.

The aim of this study was to verify the length of post-partum anoestrus (PPA) in Anglo-Nubian and Saanen goats raised in North-eastern Brazi

Multiscale structure of the gravitational wave signal from GW150914 based on the nonextensivity qq-triplet

We study the first gravitational wave, GW150914, detected by advanced LIGO and constructed from the data of measurement of strain relative deformation of the fabric of spacetime. We show that the time series from the gravitational wave obeys Tsallis's $q$-Gaussian distribution as a probability density and its dynamics evolve of the three associated Tsallis' indices named $q$-triplet. This fact strongly suggests that these black hole merger systems behave in a non-extensive manner. Furthermore, our results point out that the entropic indexes obtained as a function of frequency are useful statistical parameters to determine the dominant frequency when black hole coalescence is achieved.Comment: 7 pages, 6 figure

Extreme value statistics for dynamical systems with noise

We study the distribution of maxima ( extreme value statistics ) for sequences of observables computed along orbits generated by random transformations. The underlying, deterministic, dynamical system can be regular or chaotic. In the former case, we show that, by perturbing rational or irrational rotations with additive noise, an extreme value law appears, regardless of the intensity of the noise, while unperturbed rotations do not admit such limiting distributions. In the case of deterministic chaotic dynamics, we will consider observables specially designed to study the recurrence properties in the neighbourhood of periodic points. Hence, the exponential limiting law for the distribution of maxima is modified by the presence of the extremal index , a positive parameter not larger than one, whose inverse gives the average size of the clusters of extreme events. The theory predicts that such a parameter is unitary when the system is perturbed randomly. We perform sophisticated numerical tests to assess how strong the impact of noise level is when finite time series are considered. We find agreement with the asymptotic theoretical results but also non-trivial behaviour in the finite range. In particular, our results suggest that, in many applications where finite datasets can be produced or analysed, one must be careful in assuming that the smoothing nature of noise prevails over the underlying deterministic dynamics

Determinação do comprimento ótimo de transectos para estimativa de necromassa floresta.

O objetivo deste trabalho foi avaliar diferentes comprimentos de transecto para determinação da necromassa florestal caída sobre o chão. Os dados são provenientes de transectos de 10 metros, medidos durante o teste de metodologia do Inventário Florestal Nacional na Amazônia, Cerrado e Caatinga, e no inventário em Santa Catarina, representando Floresta Ombrófila Mista e Floresta Estacional Decidual. O comparativo do coeficiente de variação, para transectos de 10 a 150 m indica que as maiores alterações desse estimador ocorrem no intervalo de 10 até 50 m, estabilizando-se a partir deste comprimento. A adoção de transectos de 10 m nas tipologias avaliadas é recomendável, pois com este comprimento ocorre uma redução de 35% na distância total de caminhamento em relação aos transectos de 20 m, para obter o mesmo erro amostral.Nota Científic