176 research outputs found

    Approximate solutions for the single soliton in a Skyrmion-type model with a dilaton scalar field

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    We consider the analytical properties of the single-soliton solution in a Skyrmion-type Lagrangian that incorporates the scaling properties of quantum chromodynamics (QCD) through the coupling of the chiral field to a scalar field interpreted as a bound state of gluons. The model was proposed in previous works to describe the Goldstone pions in a dense medium, being also useful for studying the properties of nuclear matter and the in-medium properties of mesons and nucleons. Guided by an asymptotic analysis of the Euler-Lagrange equations, we propose approximate analytical representations for the single soliton solution in terms of rational approximants exponentially localized. Following the Pad\'e method, we construct a sequence of approximants from the exact power series solutions near the origin. We find that the convergence of the approximate representations to the numerical solutions is considerably improved by taking the expansion coefficients as free parameters and then minimizing the mass of the Skyrmion using our ans\"atze for the fields. We also perform an analysis of convergence by computation of physical quantities showing that the proposed analytical representations are very useful useful for phenomenological calculations.Comment: 13 pages, 3 eps figures, version to be published in Phys.Rev.

    Valoração econômica da perda de solo na cultura de cana-de-açúcar colhida crua e queimada no município de Campos dos Goytacazes.

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    Este trabalho foi realizado no Município de Campos dos Goytacazes, RJ e teve como objetivo valorar economicamente as perdas de solo em relação aos nutrientes perdidos na cultura de cana-de-açúcar sob dois sistemas distintos de colheita, cana-de-açúcar crua e queimada em áreas de baixada e de tabuleiro. Utilizou-se a Universal Soil Loss Equation ? USLE e o método do custo de reposição de nutrientes, para realizar a estimação econômica das perdas de solo. Os resultados mostram que a taxa de perda de solo da cana-de-açúcar queimada foi quatro vezes maior quando comparada à taxa para cana-de-açúcar colhida crua para ambas as áreas estudadas. O custo de reposição dos nutrientes perdidos no cultivo da cana-de-açúcar sob sistema de colheita com queima prévia apresentou um valor de R10,53porhectare,jaˊocustoparaaˊreacomcanacruafoideR10,53 por hectare, já o custo para área com cana crua foi de R 2,61 por hectare em área de baixada e de R43,59porhectareparacanaqueimadaeR 43,59 por hectare para cana queimada e R 10,89 para cana crua em tabuleiro. Dessa forma, o sistema de manejo da colheita da cana crua contribui ambientalmente e economicamente para a preservação da fertilidade do solo

    TDANetVis: Suggesting temporal resolutions for graph visualization using zigzag persistent homology

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    Temporal graphs are commonly used to represent complex systems and track the evolution of their constituents over time. Visualizing these graphs is crucial as it allows one to quickly identify anomalies, trends, patterns, and other properties leading to better decision-making. In this context, the to-be-adopted temporal resolution is crucial in constructing and analyzing the layout visually. The choice of a resolution is critical, e.g., when dealing with temporally sparse graphs. In such cases, changing the temporal resolution by grouping events (i.e., edges) from consecutive timestamps, a technique known as timeslicing, can aid in the analysis and reveal patterns that might not be discernible otherwise. However, choosing a suitable temporal resolution is not trivial. In this paper, we propose TDANetVis, a methodology that suggests temporal resolutions potentially relevant for analyzing a given graph, i.e., resolutions that lead to substantial topological changes in the graph structure. To achieve this goal, TDANetVis leverages zigzag persistent homology, a well-established technique from Topological Data Analysis (TDA). To enhance visual graph analysis, TDANetVis also incorporates the colored barcode, a novel timeline-based visualization built on the persistence barcodes commonly used in TDA. We demonstrate the usefulness and effectiveness of TDANetVis through a usage scenario and a user study involving 27 participants.Comment: This document contains the main article and supplementary material. For associated code and software, see https://github.com/raphaeltinarrage/TDANetVi

    Quantitative optical spectroscopy of 87^{87}Rb vapour in the Voigt geometry in DC magnetic fields up to 0.4T

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    We present a detailed spectroscopic investigation of a thermal ⁸⁷Rb atomic vapour in magnetic fields up to 0.4T in the Voigt geometry. We fit experimental spectra with our theoretical model ElecSus and find excellent quantitative agreement, with RMS errors of backsim0.3%. We extract the magnetic field strength and the angle between the polarisation of the light and the magnetic field from the atomic signal and find excellent agreement to within backsim1% with a commercial Hall probe. Finally, we present an investigation of the relative sensitivity of this technique to variations in the field strength and angle with a view to enabling atom-based high-field vector magnetometry

    Reproductive Management of the Male Goat: A Review

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    Objective: Describe the factors affecting male goat (ram) reproduction and the selection and management strategies to improve their reproductive efficiency. Design/methodology/approach: By reviewing published information, the description of the main factors that affect the reproductive capacity of rams and some management strategies for their reduction was made. Study emphases were on the evaluation of seminal quality, libido, and the selection of rams to be used in the herd. Results: Proper ram alimentation reduces the age at puberty, and improves testicular and seminal characteristics, and sexual behavior. The effect of seasonality can be improved by using melatonin implants and adequate nutrition. Limitations/implications: In goat production systems, rams are important for the production of quality livestock, and the products and by-products from this group of species. Understanding the impact of environmental factors such as nutrition, seasonality, and physiological processes on the reproductive capacity of rams promotes the establishment of management strategies to better understand what is important when selecting rams as sperm donors to improve product quality and to obtain greater herd production. Findings/conclusions: Adequate ram nutrition improves herd fertility. Seasonal reproduction affects the reproductive capacity of rams as sperm donors, yet there are management alternatives to reduce such seasonal effects on their reproductive performance.Objective: To describe the factors affecting male goat (buck) reproduction and the selection and management strategies to improve their reproductive efficiency. Design/Methodology/Approach: By reviewing published information, the main factors that affect the reproductive capacity of bucks and some management strategies for their reduction were described. Emphasis was on the evaluation of seminal quality, libido, and the selection of sires to be used in the herd. Results: Proper sire diet reduces age at puberty and improves testicular and seminal characteristics, as well as sexual behavior. The effect of seasonality can be improved by using melatonin implants and adequate nutrition. Study Limitations/Implications: In goat production systems, bucks are important for the production of quality livestock and the products and byproducts from this species. Understanding the impact of environmental factors such as nutrition, seasonality, and physiological processes on the reproductive capacity of bucks promotes the establishment of management strategies to better understand what is important when selecting sires as sperm donors to improve product quality and to obtain greater herd production. Findings/Conclusions: Adequate sire nutrition improves herd fertility. Seasonal reproduction affects the reproductive capacity of sires as sperm donors, yet there are management alternatives to reduce such seasonal effects on their reproductive performance
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