627 research outputs found

    Approach to a rational rotation number in a piecewise isometric system

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    We study a parametric family of piecewise rotations of the torus, in the limit in which the rotation number approaches the rational value 1/4. There is a region of positive measure where the discontinuity set becomes dense in the limit; we prove that in this region the area occupied by stable periodic orbits remains positive. The main device is the construction of an induced map on a domain with vanishing measure; this map is the product of two involutions, and each involution preserves all its atoms. Dynamically, the composition of these involutions represents linking together two sector maps; this dynamical system features an orderly array of stable periodic orbits having a smooth parameter dependence, plus irregular contributions which become negligible in the limit.Comment: LaTeX, 57 pages with 13 figure

    <b><i>Topoisomerase 1</i></b> Promoter Variants and Benefit from Irinotecan in Metastatic Colorectal Cancer Patients

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    Objective: Topoisomerase 1 (topo-1) is an important target for the treatment of metastatic colorectal cancer (CRC). The aim of the present study was to evaluate the correlation between topo-1 single-nucleotide polymorphisms (SNPs) and clinical outcome in metastatic CRC (mCRC) patients. Methods: With the use of specific software (PROMO 3.0), we performed an in silico analysis of topo-1 promoter SNPs; the rs6072249 and rs34282819 SNPs were included in the study. DNA was extracted from 105 mCRC patients treated with FOLFIRI ± bevacizumab in the first line. SNP genotyping was performed by real-time PCR. Genotypes were correlated with clinical parameters (objective response rate, progression-free survival, and overall survival). Results: No single genotype was significantly associated with clinical variables. The G allelic variant of rs6072249 topo-1 SNP is responsible for GC factor and X-box-binding protein transcription factor binding. The same allelic variant showed a nonsignificant trend toward a shorter progression-free survival (GG, 7.5 months; other genotypes, 9.3 months; HR 1.823, 95% CI 0.8904-3.734; p = 0.1). Conclusion: Further analyses are needed to confirm that the topo-1 SNP rs6072249 and transcription factor interaction could be a part of tools to predict clinical outcome in mCRC patients treated with irinotecan-based regimens

    Recomendação de adubação para aveia, em dois sistemas de plantio, em Latossolo Vermelho distrófico típico.

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    bitstream/CPPSE/14082/1/PROCIComT34ACP2002.00008.pd

    Ergodicity criteria for non-expanding transformations of 2-adic spheres

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    In the paper, we obtain necessary and sufficient conditions for ergodicity (with respect to the normalized Haar measure) of discrete dynamical systems on 2-adic spheres S2r(a)\mathbf S_{2^{-r}}(a) of radius 2r2^{-r}, r1r\ge 1, centered at some point aa from the ultrametric space of 2-adic integers Z2\mathbb Z_2. The map f ⁣:Z2Z2f\colon\mathbb Z_2\to\mathbb Z_2 is assumed to be non-expanding and measure-preserving; that is, ff satisfies a Lipschitz condition with a constant 1 with respect to the 2-adic metric, and ff preserves a natural probability measure on Z2\mathbb Z_2, the Haar measure μ2\mu_2 on Z2\mathbb Z_2 which is normalized so that μ2(Z2)=1\mu_2(\mathbb Z_2)=1

    Resposta de aveia à adubação, em dois sistemas de plantio.

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    O objetivo deste trabalho foi determinar para a linhagem de aveia UPF 87111, a dose de NPK que possibilite obter máxima produção e qualidade de forragem, em dois sistemas de plantio: convencional e cobertura morta. O delineamento experimental foi fatorial fracionado tipo (1/2)43 com dois blocos ao acaso, um total de 32 parcelas sem repetição. Os tratamentos foram quatro doses de N e de K2O (0,70,140 e 210 Kg ha-1), na forma de uréia e de cloreto de potássio e quatro doses de N e K2O (0,70,140 e 210 kg ha-1), na forma de ureia e de cloreto de potássio e quatro doses de P (0,60, 120, 180 kg ha-1 de P2O5), como super fosfato triplo. Nos dois sistemas de plantio a resposta ao nitrogênio apresentou o maior retorno em produção de forragem por unidade de nutriente aplicado. Embora no plantio com cobertura morta a aplicado. Embora no plantio com cobertura morta a eficiência do N tenha sido menor, provavelmente devido a sua imobilização parcial pela palhada, o potencial de produção foi 26% superior ao do plantio convencional

    Quantum Computing of Poincare Recurrences and Periodic Orbits

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    Quantum algorithms are built enabling to find Poincar\'e recurrence times and periodic orbits of classical dynamical systems. It is shown that exponential gain compared to classical algorithms can be reached for a restricted class of systems. Quadratic gain can be achieved for a larger set of dynamical systems. The simplest cases can be implemented with small number of qubits.Comment: revtex, 5 pages, research at Quantware MIPS Center (see http://www.quantware.ups-tlse.fr); minor changes and references adde

    Alterações microbianas e químicas de um gleissolo sob macaubeiras nativas em função da variação sazonal e espacial.

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    RESUMO: A macaúba (Acrocomia aculeata) é uma alternativa para a produção de biodiesel e, consorciada com pastagem, pode auxiliar na recuperação de áreas degradadas. O objetivo deste trabalho foi estudar as alterações nos atributos microbiológicos, na matéria orgânica e no N total do solo, em função da variação sazonal e espacial em um Gleissolo sob maciço de macaubeiras nativas, no Cerrado. O estudo observacional foi realizado na região de Planaltina de Goiás, na Fazenda Agropecuária Santa Fé. Foram selecionadas dez árvores em uma mata com macaubeiras nativas no bioma cerrado. A coleta de solo foi realizada na camada de 0 a 10 centímetros de profundidade, sob uma linha horizontal, imaginária, traçada a partir da base do caule das macaubeiras. As amostras de solo foram coletadas a 50, 150 e 250 centímetros de distância do caule da palmeira, durante o verão chuvoso (março de 2010) e inverno seco (julho 2010). Para a avaliação estatística das variáveis observadas, utilizou-se um modelo misto. As médias das variáveis observadas foram submetidas a testes para verificar se seguiam a distribuição normal, e a homogeneidade de variâncias. Em seguida, os dados foram submetidos ao teste F e as médias foram comparadas pelo teste t. Os atributos carbono microbiano (Cmic), respiração basal (RB), quociente metabólico (qCO2), a matéria orgânica do solo (MOS) e a relação C/N do solo são sensíveis à variação sazonal e espacial em mata de macaubeiras no Cerrado. O nitrogênio total (NT) foi sensível à variação espacial. A microbiota presente no solo sob macaubal se manteve mais equilibrada durante o período seco, apresentando maiores teores de carbono microbiano e quociente microbiano e menor quociente metabólico e relação C/N do solo

    Inverse Modeling for MEG/EEG data

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    We provide an overview of the state-of-the-art for mathematical methods that are used to reconstruct brain activity from neurophysiological data. After a brief introduction on the mathematics of the forward problem, we discuss standard and recently proposed regularization methods, as well as Monte Carlo techniques for Bayesian inference. We classify the inverse methods based on the underlying source model, and discuss advantages and disadvantages. Finally we describe an application to the pre-surgical evaluation of epileptic patients.Comment: 15 pages, 1 figur

    Holomorphic Quantization on the Torus and Finite Quantum Mechanics

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    We construct explicitly the quantization of classical linear maps of SL(2,R)SL(2, R) on toroidal phase space, of arbitrary modulus, using the holomorphic (chiral) version of the metaplectic representation. We show that Finite Quantum Mechanics (FQM) on tori of arbitrary integer discretization, is a consistent restriction of the holomorphic quantization of SL(2,Z)SL(2, Z) to the subgroup SL(2,Z)/ΓlSL(2, Z)/\Gamma_l, Γl\Gamma_l being the principal congruent subgroup mod l, on a finite dimensional Hilbert space. The generators of the ``rotation group'' mod l, Ol(2)SL(2,l)O_{l}(2)\subset SL(2,l), for arbitrary values of l are determined as well as their quantum mechanical eigenvalues and eigenstates.Comment: 12 pages LaTeX (needs amssymb.sty). Version as will appear in J. Phys.
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