Asymptotic behavior of global entropy solutions for nonstrictly hyperbolic systems with linear damping

In this paper we investigate the large time behavior of the global weak entropy solutions to the symmetric Keyftiz-Kranzer system with linear damping. It is proved that as t tends to infinite the entropy solutions tend to zero in the L p nor

A Bendixson-Dulac theorem for some piecewise systems

The Bendixson-Dulac Theorem provides a criterion to find upper bounds for the number of limit cycles in analytic differential systems. We extend this classical result to some classes of piecewise differential systems. We apply it to three different Liénard piecewise differential systems ¨ x+f±(x)˙ x+x = 0. The first is linear, the second is rational and the last corresponds to a particular extension of the cubic van der Pol oscillator. In all cases, the systems present regions in the parameter space with no limit cycles and others having at most one

Ultrastructure of the Intramandibular Gland of Workers and Queens of the Stingless Bee, Melipona quadrifasciata

The intramandibular glands of workers and queens of Melipona quadrifasciata Lepeletier (Hymenoptera: Apidae), at different ages and from different functional groups, were studied using light and transmission electron microscopy. The results demonstrated that these glands are composed of two types of secretory structures: 1.A hypertrophied epidermis on the dorsal side of the mandible that is an epithelial gland. 2. Free secretory cells filling the inner spaces of the appendices that constitute a unicellular gland. The epithelial gland is larger in the young (1-2-day-old workers), and the gland becomes involuted during the nurse worker stage. The unicellular glands of the workers posses some secretion during all of the studied phases, but secretory activity is more intensive in the foraging workers. Vesicles of secretion are absent in the unicellular glands of queens. These results demonstrate that these glands show functional adaptations in different castes corresponding to the functions of each caste

New lower bound for the Hilbert number in low degree Kolmogorov systems

Our main goal in this paper is to study the number of small-amplitude isolated periodic orbits, so-called limit cycles, surrounding only one equilibrium point a class of polynomial Kolmogorov systems. We denote by $\mathcal M_{K}(n)$ the maximum number of limit cycles bifurcating from the equilibrium point via a degenerate Hopf bifurcation for a polynomial Kolmogorov vector field of degree $n$. In this work, we obtain another example such that $\mathcal M_{K}(3)\geq 6$. In addition, we obtain new lower bounds for $\mathcal M_{K}(n)$ proving that $\mathcal M_{K}(4)\geq 13$ and $\mathcal M_{K}(5)\geq 22$

Land Suitability Evaluation of Abandoned Tin-mining Areas for Agricultural Development in Bangka Island, Indonesia

Kepulauan Bangka Belitung, Indonesia is one of the tin mineral-producer in the world. Agricultural crops could be a wise option for the reclamation since abandoned tin-mining lands have a high potency to be used as agricultural lands. This study was aimed to evaluate of the land/soil characteristics of abandoned tin-mining areas and to establish land suitability of the land area for agriculture used to formulate appropriate land development measures and amelioration strategies for utilization of mined areas for crop production. The land evaluation was conducted by comparing the land characteristics in every type of abandoned tin-mining areas with its crop requirements. The current suitability showed that in general food crops, vegetable crops, fruit crops, and industrial crops were consider as not suitable (N). Spice and medicinal crops [pepper (Piper nigrum L.) and citronella (Andropogoh nardus L. Rendle)] were consider as not suitable (N), while the Jatropha (Jatropha curcas L.) and Kemiri Sunan (Aleurites moluccana L. Willd) crops were considered as marginally suitable (S3) in abandoned tin-mining areas. The forest crops and forage crops were considered as marginally suitable (S3). The water availability, soil texture, and low soil fertility were considered as the limiting factors of all crops to get optimum production. For agricultural development, the soil physical and chemical properties of abandoned tin-mining land must be improved through integrated farming

Towards Automated Semantic Segmentation in Mammography Images

Mammography images are widely used to detect non-palpable breast lesions or nodules, preventing cancer and providing the opportunity to plan interventions when necessary. The identification of some structures of interest is essential to make a diagnosis and evaluate image adequacy. Thus, computer-aided detection systems can be helpful in assisting medical interpretation by automatically segmenting these landmark structures. In this paper, we propose a deep learning-based framework for the segmentation of the nipple, the pectoral muscle, the fibroglandular tissue, and the fatty tissue on standard-view mammography images. We introduce a large private segmentation dataset and extensive experiments considering different deep-learning model architectures. Our experiments demonstrate accurate segmentation performance on variate and challenging cases, showing that this framework can be integrated into clinical practice.Comment: 6 page

Período crítico de competencia de la Zanahoria (Daucus carota L.) y malezas asociadas al cultivo

Las malezas constituyen uno de los problemas fitosanitarios que afectan la rentabilidad de los cultivos. El periodo crítico de competencia con el cultivo (PCC), permite prever el nivel de interferencia de las malezas sobre la producción del cultivo de interés. El objetivo de esta investigación fue determinar el PCC entre zanahoria y las plantas asociadas al cultivo, en el municipio de Ventaquemada, departamento de Boyacá, implementando un diseño en Bloques Completos al Azar, con 12 tratamientos y cuatro repeticiones, el cual incluía un grupo de tratamientos libres de malezas por un periodo de tiempo (10, 20, 30, 40 ó 50 días), al término del cual se permitía el crecimiento de las mismas en el cultivo, de modo que el cultivo estuviese primero libre y luego en competencia (LC) y en el segundo grupo de tratamientos se permitía primero el desarrollo del proceso de competencia entre la maleza y el cultivo por un intervalo de tiempo igual al del grupo anterior y luego se retiraban las malezas. El mayor número de plantas cosechadas se obtuvo en la parcela libre de competencia durante los primeros 50 días después de emergencia. El mayor rendimiento se obtuvo en el tratamiento que se mantuvo limpio durante todo el ciclo de cultivo, con una producción de 5810g m-2, superior en 2252g a la obtenida en el punto crítico de competencia. para las condiciones evaluadas, el periodo crítico de competencia en zanahoria, se sitúa entre los 20 a 45 días, después de la emergencia del cultivo