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Search Results: 1 - 10 of 14323 matches for " Paulino Ribeiro Villas Boas "
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Modeling Worldwide Highway Networks
Paulino Ribeiro Villas Boas,Francisco Aparecido Rodrigues,Luciano da Fontoura Costa
Physics , 2009,
Abstract: This letter addresses the problem of modeling the highway systems of different countries by using complex networks formalism. More specifically, we compare two traditional geographical models with a modified geometrical network model where paths, rather than edges, are incorporated at each step between the origin and destination nodes. Optimal configurations of parameters are obtained for each model and used in the comparison. The highway networks of Brazil, the US and England are considered and shown to be properly modeled by the modified geographical model. The Brazilian highway network yielded small deviations that are potentially accountable by specific developing and sociogeographic features of that country.
Rapid Differentiation of Closely Related Citrus Genotypes by Fluorescence Spectroscopy  [PDF]
Dayse Drielly Souza Santana-Vieira, Débora Marcondes Bastos Pereira Milori, Paulino Ribeiro Villas Boas, Marina Fran?a e Silva, Magno Guimar?es Santos, Fernanda Amato Gaiotto, Walter dos Santos Soares Filho, Abelmon da Silva Gesteira
Advances in Bioscience and Biotechnology (ABB) , 2014, DOI: 10.4236/abb.2014.511105
Abstract: The differentiation of closely related Citrus genotypes is a meticulous, laborious, and time-consuming task that involves the assessment of complex traits such as growth, tolerance to stress, photosynthetic efficiency, yield, and many others. Such a task is generally accomplished either by analyzing specific features of adult plants or by applying molecular markers to young trees. On one hand, only after plants start yielding can distinct genotypes be differentiated by comparing their fruit sizes, shapes, taste, and the number of seeds. On the other hand, molecular markers are expensive, and demand expertise and time for the analysis of a larger number of plants. For these reasons, the development of techniques that could assist in an early, quick and accurate differen-tiation of closely related Citrus varieties is of utmost importance. In this context, laser-induced fluorescence spectroscopy (LIFS) is a promising technique, since it is rapid, highly sensitive, and inexpensive. Previous studies showed that LIFS can differentiate a variety of sweet orange. However, this new study aimed to determine LIFS accuracy in the differentiation and grouping of very closely varieties of four Sunki mandarin selections: Comum, Florida, Tropical, and Maravilha. Furthermore we compared the results with ISSR and SSR molecular markers for the same varieties. LIFS technique distinguished the four selections with accuracy greater than 70%. Only with molecular markers was possible distinguishing clearly Tropical from Maravilha, but not Comum from Florida selections. In this way the results suggest that LIFS may be a sound tool for helping the identification of closely Citrus varieties.
Physical and Chemical Matrix Effects in Soil Carbon Quantification Using Laser-Induced Breakdown Spectroscopy  [PDF]
Aline Segnini, Alfredo Augusto Pereira Xavier, Pedro Luís Otaviani-Junior, Edilene Cristina Ferreira, Alex Marcel Watanabe, Marco Aurélio Speran?a, Gustavo Nicolodelli, Paulino Ribeiro Villas-Boas, Patrícia Perondi Anch?o Oliveira, Débora Marcondes Bastos Pereira Milori
American Journal of Analytical Chemistry (AJAC) , 2014, DOI: 10.4236/ajac.2014.511080
Abstract: Advanced field methods of carbon (C) analysis should now be capable of providing repetitive, sequential measurements for the evaluation of spatial and temporal variation at a scale that was previously unfeasible. Some spectroscopy techniques, such as laser-induced breakdown spectroscopy (LIBS), have portable features that may potentially lead to clean and rapid alternative approaches for this purpose. The goal of this study was to quantify the C content of soils with different textures and with high iron and aluminum concentrations using LIBS. LIBS emission spectra from soil pellets were captured, and the C content was estimated (emission line of C (I) at 193.03 nm) after spectral offset and aluminum spectral interference correction. This technique is highly portable and could be ideal for providing the soil C content in a heterogeneous experiment. Dry combustion was used as a reference method, and for calibration a conventional linear model was evaluated based on soil textural classes. The correlation between reference and LIBS values showed r = 0.86 for medium-textured soils and r = 0.93 for fine-textured soils. The data showed that better correlation and lower error (14%) values were found for the fine-textured LIBS model. The limit of detection (LOD) was found to be 0.32% for medium-textured soils and 0.13% for fine-textured soils. The results indicated that LIBS quantification can be affected by the texture and chemical composition of soil. Signal treatment was shown to be very important for mitigation of these interferences and to improve quantification.
Chain motifs: The tails and handles of complex networks
Paulino R. Villas Boas,Francisco A. Rodrigues,Gonzalo Travieso,Luciano da F. Costa
Physics , 2007, DOI: 10.1103/PhysRevE.77.026106
Abstract: Great part of the interest in complex networks has been motivated by the presence of structured, frequently non-uniform, connectivity. Because diverse connectivity patterns tend to result in distinct network dynamics, and also because they provide the means to identify and classify several types of complex networks, it becomes important to obtain meaningful measurements of the local network topology. In addition to traditional features such as the node degree, clustering coefficient and shortest path, motifs have been introduced in the literature in order to provide complementary description of the networks connectivity. The current work proposes a new type of motifs, namely chains of nodes, namely sequences of connected nodes with degree two. These chains have been subdivided into cords, tails, rings and handles, depending on the type of their extremities (e.g. open or connected). A theoretical analysis of the density of such motifs in random and scale free networks is described, and an algorithm for identifying those motifs in general networks is presented. The potential of considering chains for network characterization has been illustrated with respect to five categories of real-world networks including 16 cases. Several interesting findings were obtained, including the fact that several chains were observed in the real-world networks, especially the WWW, books, and power-grid. The possibility of chains resulting from incompletely sampled networks is also investigated.
Border trees of complex networks
Paulino R. Villas Boas,Francisco A. Rodrigues,Gonzalo Travieso,Luciano da F. Costa
Physics , 2007, DOI: 10.1088/1751-8113/41/22/224005
Abstract: The comprehensive characterization of the structure of complex networks is essential to understand the dynamical processes which guide their evolution. The discovery of the scale-free distribution and the small world property of real networks were fundamental to stimulate more realistic models and to understand some dynamical processes such as network growth. However, properties related to the network borders (nodes with degree equal to one), one of its most fragile parts, remain little investigated and understood. The border nodes may be involved in the evolution of structures such as geographical networks. Here we analyze complex networks by looking for border trees, which are defined as the subgraphs without cycles connected to the remainder of the network (containing cycles) and terminating into border nodes. In addition to describing an algorithm for identification of such tree subgraphs, we also consider a series of their measurements, including their number of vertices, number of leaves, and depth. We investigate the properties of border trees for several theoretical models as well as real-world networks.
Características biométricas de mudas de Tabebula chrysotricha(standl.) formadas em diferentes substratos e solu??es de fertirriga??o, quando plantadas em campo
Sarzi, Isabele;Villas Boas, Roberto Lyra;Silva, Magali Ribeiro da;Carvalho, José Luis de;
Revista árvore , 2010, DOI: 10.1590/S0100-67622010000200006
Abstract: the work aimed to study the formation of tabebuia chrysotricha standl. seedlings in function of four substrates, varying the fertirrigation solutions. to compose the substrate, fibrous and granulated coconut fiber was used, obtaining the following treatments: 100% fibrous, 60% fibrous and 40% granulated, 40% fibrous and 60% granulated and 100% granulated. the base fertilization was the same for all treatments and the solutions of fertilization varied in order to obtain complete solutions with electric conductivities of 1.06 ds m-1, 2.12 ds m-1, 3.2 ds m-1 and 4.25 ds m-1. the propagative material was sowed directly into plastic containers (120ml) with the respective substrates. the fertilization was received through sub irrigation once a week, respecting the treatments of fertilizations. when the seedlings reached 20cm of height, approximately, they were replaced under black screens (9% of shading), where they remained until planting in taubaté-sp. seedlings produced in coconut fiber 100% granulate reached, in the field, higher heights, stem diameters and number of leaves. in function of applied solutions, heights of the aerial part were homogeneous starting from 167 days after planting. the production of t. chrysotricha seedlings is recommended in granulated coconut fiber substrate and fertilizer solutions with electric conductivity of 1.06 ds m-1.
An Information Theoretic Approach to Understanding the Micro Foundations of Macro Processes  [PDF]
Sofia B. Villas-Boas, George Judge
Theoretical Economics Letters (TEL) , 2013, DOI: 10.4236/tel.2013.31008
Abstract: In the context of a simple equilibrium macro process we suggest a probability basis for recovering information regarding the unknown and unobservable micro process, and solving the resulting inverse problem.
Analyzing and Modeling Real-World Phenomena with Complex Networks: A Survey of Applications
Luciano da F. Costa,Osvaldo N. Oliveira Jr.,Gonzalo Travieso,Francisco A. Rodrigues,Paulino R. Villas Boas,Lucas Antiqueira,Matheus P. Viana,Luis E. C. da Rocha
Physics , 2007, DOI: 10.1080/00018732.2011.572452
Abstract: The success of new scientific areas can be assessed by their potential for contributing to new theoretical approaches and in applications to real-world problems. Complex networks have fared extremely well in both of these aspects, with their sound theoretical basis developed over the years and with a variety of applications. In this survey, we analyze the applications of complex networks to real-world problems and data, with emphasis in representation, analysis and modeling, after an introduction to the main concepts and models. A diversity of phenomena are surveyed, which may be classified into no less than 22 areas, providing a clear indication of the impact of the field of complex networks.
Prof. Alex Villas Boas
Revista Eletr?nica Espa?o Teológico , 2008,
Abstract: O texto procura refletir sobre o diálogo contemporaneo da Teologia com a Arte a partir da antropologia contida em ambas que permite re-significar: 1) o aspecto soteriológico da fé, como aquela que vem salvar o humano gerando comunh o e n o condená-lo, gerando marginaliza o; 2) refazer os fundamentos da raz o como raz o fria para uma raz o voltada para seu compromisso com a vida.
O portfólio no curso de pedagogia: ampliando o diálogo entre professor e aluno
Villas Boas, Benigna Maria de Freitas;
Educa??o & Sociedade , 2005, DOI: 10.1590/S0101-73302005000100013
Abstract: the article presents the results of a research conducted in the pedagogy course offered by the college of education of the university of brasília to in-service teachers who work in public elementary schools with grades one through four. the student-teachers are assessed by means of portfolios for evaluation procedure. the issues discussed are: a) the mediators' perceptions on student-teachers' reactions to the use of portfolios; b) the student-teacher's perceptions on the portfolio construction. it was noticed that: the use of the portfolio as an assessment procedure was previously unknown to the whole group; initially, there was resistance of some student-teachers regarding the portfolio construction, but as the process developed, the confidence not only of the mediators but also of the student-teachers increased; the portfolio became the organizer axle of the pedagogic course activities. in conclusion, for the portfolio to be part of the committed assessment process of student- teachers' learning and to be supported in construction, reflection, creativity, partnership, self-assessment and autonomy, it must be included in the pedagogical work that considers these same principles.
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