26,487 research outputs found

    Torsion-Adding and Asymptotic Winding Number for Periodic Window Sequences

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    In parameter space of nonlinear dynamical systems, windows of periodic states are aligned following routes of period-adding configuring periodic window sequences. In state space of driven nonlinear oscillators, we determine the torsion associated with the periodic states and identify regions of uniform torsion in the window sequences. Moreover, we find that the measured of torsion differs by a constant between successive windows in periodic window sequences. We call this phenomenon as torsion-adding. Finally, combining the torsion and the period adding rules, we deduce a general rule to obtain the asymptotic winding number in the accumulation limit of such periodic window sequences

    Detectability of the First Cosmic Explosions

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    We present a fully self-consistent simulation of a synthetic survey of the furthermost cosmic explosions. The appearance of the first generation of stars (Population III) in the Universe represents a critical point during cosmic evolution, signaling the end of the dark ages, a period of absence of light sources. Despite their importance, there is no confirmed detection of Population III stars so far. A fraction of these primordial stars are expected to die as pair-instability supernovae (PISNe), and should be bright enough to be observed up to a few hundred million years after the big bang. While the quest for Population III stars continues, detailed theoretical models and computer simulations serve as a testbed for their observability. With the upcoming near-infrared missions, estimates of the feasibility of detecting PISNe are not only timely but imperative. To address this problem, we combine state-of-the-art cosmological and radiative simulations into a complete and self-consistent framework, which includes detailed features of the observational process. We show that a dedicated observational strategy using 8\lesssim 8 per cent of total allocation time of the James Webb Space Telescope mission can provide us up to 915\sim 9-15 detectable PISNe per year.Comment: 9 pages, 8 figures. Minor corrections added to match published versio

    de Broglie-Proca and Bopp-Podolsky massive photon gases in cosmology

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    We investigate the influence of massive photons on the evolution of the expanding universe. Two particular models for generalized electrodynamics are considered, namely de Broglie-Proca and Bopp-Podolsky electrodynamics. We obtain the equation of state (EOS) P=P(ε)P=P(\varepsilon) for each case using dispersion relations derived from both theories. The EOS are inputted into the Friedmann equations of a homogeneous and isotropic space-time to determine the cosmic scale factor a(t)a(t). It is shown that the photon non-null mass does not significantly alter the result at1/2a\propto t^{1/2} valid for a massless photon gas; this is true either in de Broglie-Proca's case (where the photon mass mm is extremely small) or in Bopp-Podolsky theory (for which mm is extremely large).Comment: 8 pages, 2 figures; v2 matches the published versio

    Reducing the parameter space for Unparticle-inspired models using white dwarf masses

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    Based on astrophysical constraints derived from Chandrasekhar's mass limit for white-dwarfs, we study the effects of the model on the parameters of unparticle-inspired gravity, on scales ΛU>1  TeV\Lambda_U > 1 \; TeV and dU1d_U \approx 1.Comment: 4 pp., 4 Fig., to appear in PR

    Development of food mass mix from brazil nut and peach palm fruit flours.

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    The forest Amazon offers a natural resources variety. Among the vegetal resources used, the Brazil nut, Bertollethia excelsa H.B.K and peach palm fruit (Bactris gasipaes, Kunth) are distinguished. The Brazil nut has a high fat amount (60% to 70%) and protein (15% to 20%). This content gives it lots of sulfur amino acids. The peach palm has considerable amounts of vitamin A (17.18 RE/g) is still high in fiber (2%). Seeking to utilize fruits potential, aimed at production and characterization of pasta mixed using ingredients Brazil nut, peach palm and wheat flour

    Retenção do dimetoato e sua relação com pH e teores de argila e matéria orgânica nos sedimentos da zona não-saturada de uma microbacia no nordeste paraense.

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    Na agricultura familiar na Amazônia oriental, em particular no nordeste do Pará, são comuns os cultivos semi-perenes com pesada aplicação de agrotóxicos. Em virtude da ampla utilização desses produtos, principalmente o dimetoato, na microbacia hidrográfica do igarapé Cumaru, município de Igarapé-Açu (PA), foi avaliada a retenção dessa substância em amostras da zona não-saturada em laboratório, verificando-se também a influência do pH e dos teores de argila e de matéria orgânica nesse processo. Entre os diversos agrotóxicos utilizados na área, o dimetoato foi selecionado por apresentar maior potencial de lixiviação, segundo o índice GUS (Groundwater Ubiquity Score). Para a quantificação da retenção do dimetoato nos sedimentos da zona não-saturada foi realizado um experimento de sorção. Este último mostrou que, em termos percentuais, a sorção do dimetoato variou de 2.5% a 36.2% (concentração inicial 20 mg.-1) e de 6.20% a 31.0 % (concentração inicial 10 mg.-1). Esses dados comprovam o elevado potencial de contaminação da água subterrânea por essa substância, devido, principalmente, à sua mobilidade e baixa retenção. Devido ao caráter hidrofóbico do dimetoato, que aumenta a sua afinidade com a matéria orgânica, a quantidade sorvida dessa substância se mostrou diretamente proporcional à de matéria orgânica presente nos sedimentos. O pH exerce efeito contrário a este, ou seja, quanto mais elevado o seu valor, menor é a quantidade de dimetoato sorvida. Em relação à variação do teor e ao tipo de argila, foi observado que esses fatores não influenciam na retenção do dimetoato, sendo esse resultado atribuído ao comportamento não iônico desse agrotóxico

    Sensory evaluation and cooking properties of macaroni at basis of brazil nut (Bertholetia excelsa) and peach palm fruit (Bactris gasipaes, Kunt) flours.

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    The Brazil nut tree, Bertholletia excelsa HBK, is explored throughout the Amazon region and its main characteristic is high content of lipids and proteins, they consist of sulfur amino acids of high biological value. The peach palm, Bactris gasipases, Kunth, is a native palm to the same region, that is grown for heart-of-palm extraction. Their fruits are mostly protein, vitamin A and fiber. The way of adding commercial value from co-products to Brazil nut processing is flour productian. That way the Brazil nut flour, for its high nutritional value and pleasant taste was used in macaroni production, along with peach palm fruit flour to improve the nutritianal properties of final product
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