176 research outputs found
Approximate solutions for the single soliton in a Skyrmion-type model with a dilaton scalar field
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.
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 R 2,61 por hectare em área de baixada e de 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
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 Rb vapour in the Voigt geometry in DC magnetic fields up to 0.4T
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
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nQuack: An R package for predicting ploidal level from sequence data using site-based heterozygosity
Premise: Traditional methods of ploidal-level estimation are tedious; using DNA sequence data for cytotype estimation is an ideal alternative. Multiple statistical approaches to leverage sequence data for ploidy inference based on site-based heterozygosity have been developed. However, these approaches may require high-coverage sequence data, use inappropriate probability distributions, or have additional statistical shortcomings that limit inference abilities. We introduce nQuack, an open-source R package that addresses the main shortcomings of current methods. Methods and Results: nQuack performs model selection for improved ploidy predictions. Here, we implement expectation maximization algorithms with normal, beta, and beta-binomial distributions. Using extensive computer simulations that account for variability in sequencing depth, as well as real data sets, we demonstrate the utility and limitations of nQuack. Conclusions: Inferring ploidy based on site-based heterozygosity alone is difficult. Even though nQuack is more accurate than similar methods, we suggest caution when relying on any site-based heterozygosity method to infer ploidy.</p
Reproductive Management of the Male Goat: A Review
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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