8,439 research outputs found

    Geometric singular perturbartion theory for non-smooth dynamical systems

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    In this article we deal with singularly perturbed Filippov systems ZΔ: (1) ˙x = ( F(x, y, Δ) if h(x, y, Δ) ≀ 0, G(x, y, Δ) if h(x, y, Δ) ≄ 0, Δy˙ = H(x, y, Δ), where Δ ∈ R is a small parameter, x ∈ Rn, n ≄ 2, and y ∈ R denote the slow and fast variables, respectively, and F, G, h, and H are smooth maps. We study the effect of singular perturbations at typical singularities of Z0. Special attention will be dedicated to those points satisfying q ∈ {h(x, y, 0) = 0} ∩ {H(x, y, 0) = 0} where F or G is tangent to {h(x, y, 0) = 0}. The persistence and the stability properties of those objects are investigated.Fundação de Amparo Ă  Pesquisa do Estado de SĂŁo Paulo (FAPESP

    Lodo de estação de tratamento de esgoto como insumo para produção agrícola.

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    bitstream/item/175414/1/Boletim-263.pdf(Embrapa Clima Temperado. Boletim de Pesquisa e Desenvolvimento, 263.

    "Sustainable Cellulose Nanofibers-Mediated Synthesis of Uniform Spinel Zn-Ferrites Nanocorals for High Performances in Supercapacitors"

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    Spinel ferrites are versatile, low-cost, and abundant metal oxides with remarkable electronic and magnetic properties, which find several applications. Among them, they have been considered part of the next generation of electrochemical energy storage materials due to their variable oxidation states, low environmental toxicity, and possible synthesis through simple green chemical processing. However, most traditional procedures lead to the formation of poorly controlled materials (in terms of size, shape, composition, and/or crystalline structure). Thus, we report herein a cellulose nanofibers-mediated green procedure to prepare controlled highly porous nanocorals comprised of spinel Zn-ferrites. Then, they presented remarkable applications as electrodes in supercapacitors, which were thoroughly and critically discussed. The spinel Zn-ferrites nanocorals supercapacitor showed a much higher maximum specific capacitance (2031.81 F g−1 at a current density of 1 A g−1) than Fe2O3 and ZnO counterparts prepared by a similar approach (189.74 and 24.39 F g−1 at a current density of 1 A g−1). Its cyclic stability was also scrutinized via galvanostatic charging/discharging and electrochemical impedance spectroscopy, indicating excellent long-term stability. In addition, we manufactured an asymmetric supercapacitor device, which offered a high energy density value of 18.1 Wh kg−1 at a power density of 2609.2 W kg−1 (at 1 A g−1 in 2.0 mol L−1 KOH electrolyte). Based on our findings, we believe that higher performances observed for spinel Zn-ferrites nanocorals could be explained by their unique crystal structure and electronic configuration based on crystal field stabilization energy, which provides an electrostatic repulsion between the d electrons and the p orbitals of the surrounding oxygen anions, creating a level of energy that determines their final supercapacitance then evidenced, which is a very interesting property that could be explored for the production of clean energy storage devices

    PAMELA and FERMI-LAT limits on the neutralino-chargino mass degeneracy

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    Searches for Dark Matter (DM) particles with indirect detection techniques have reached important milestones with the precise measurements of the anti-proton and gamma-ray spectra, notably by the PAMELA and FERMI-LAT experiments. While the gamma-ray results have been used to test the thermal Dark Matter hypothesis and constrain the Dark Matter annihilation cross section into Standard Model (SM) particles, the anti-proton flux measured by the PAMELA experiment remains relatively unexploited. Here we show that the latter can be used to set a constraint on the neutralino-chargino mass difference. To illustrate our point we use a Supersymmetric model in which the gauginos are light, the sfermions are heavy and the Lightest Supersymmetric Particle (LSP) is the neutralino. In this framework the W^+ W^- production is expected to be significant, thus leading to large anti-proton and gamma-ray fluxes. After determining a generic limit on the Dark Matter pair annihilation cross section into W^+ W^- from the anti-proton data only, we show that one can constrain scenarios in which the neutralino-chargino mass difference is as large as ~ 20 GeV for a mixed neutralino (and intermediate choices of the anti-proton propagation scheme). This result is consistent with the limit obtained by using the FERMI-LAT data. As a result, we can safely rule out the pure wino neutralino hypothesis if it is lighter than 450 GeV and constitutes all the Dark Matter.Comment: 22page

    Geometric analysis of female pelvic floor muscles by using manual segmentation

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    Magnetic Resonance Imaging (MRI) has been used in the diagnostic evaluation of the pelvic floor dysfunctions. MRI can contribute to generate 3D solids of pelvic floor muscles through manual segmentation. The aim of this study is to calculate the area and its moment of inertia of 8 female pelvic floor muscles by using manual segmentation technique. Based on CAD software manual segmentation was used. To build 3D reconstruction models, through of twenty consecutive images. The models were made through splines in each sketch, documenting changes in the pubovisceral muscle (a part from the pelvic floor muscles) from the pubis to coccyx. Two sketches were chosen and biomechanics properties like area and stiffness (moment of inertia) were acquired for each sketch used to generate the pubovisceral muscles. The moment of inertia of the pubovisceral muscle decreases following the order: anterior sketch and posterior sketch. Higher values for the moment of inertia can be encountered in anterior sketcher. This conclusion can lead to more stability in the anterior compartment of pelvic floor visceral

    Low levels of taurine introgression in the current Brazilian Nelore and Gir indicine cattle populations

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    Background: Nelore and Gir are the two most important indicine cattle breeds for production of beef and milk in Brazil. Historical records state that these breeds were introduced in Brazil from the Indian subcontinent, crossed to local taurine cattle in order to quickly increase the population size, and then backcrossed to the original breeds to recover indicine adaptive and productive traits. Previous investigations based on sparse DNA markers detected taurine admixture in these breeds. High-density genome-wide analyses can provide high-resolution information on the genetic composition of current Nelore and Gir populations, estimate more precisely the levels and nature of taurine introgression, and shed light on their history and the strategies that were used to expand these breeds. Results: We used the high-density Illumina BovineHD BeadChip with more than 777 K single nucleotide polymorphisms (SNPs) that were reduced to 697 115 after quality control filtering to investigate the structure of Nelore and Gir populations and seven other worldwide populations for comparison. Multidimensional scaling and model-based ancestry estimation clearly separated the indicine, European taurine and African taurine ancestries. The average level of taurine introgression in the autosomal genome of Nelore and Gir breeds was less than 1% but was 9% for the Brahman breed. Analyses based on the mitochondrial SNPs present in the Illumina BovineHD BeadChip did not clearly differentiate taurine and indicine haplotype groupings. Conclusions: The low level of taurine ancestry observed for both Nelore and Gir breeds confirms the historical records of crossbreeding and supports a strong directional selection against taurine haplotypes via backcrossing. Random sampling in production herds across the country and subsequent genotyping would be useful for a more complete view of the admixture levels in the commercial Nelore and Gir populations.(VLID)90707
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