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Copyright of Divulgaciones Matematicas is the property of Universidad del Zulia, Facultad Experimental de Ciencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Saber, Ciencia y Libertas is the property of Saber, Ciencia y Libertad and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this article is to analyze the collaborative mechanisms reported by the socioproductive actors of Usiacurí-Atlantic for the development of sustainable alternative tourism in times of pandemic. The methodology corresponds to an analytical research with the model of structural analysis of relationships in networks with support of adjacency matrix. Even though the relationships with various actors in the network are moderate, they are mostly circumstantial, showing that there are various mechanisms of collaboration that can be used in a new tourism model that allows the new scenarios of health, cultural, social and economic crisis resulting from the Covid-19 pandemic to be faced. [ABSTRACT FROM AUTHOR]

The Council of Citizen Participation and Social Control in Ecuador needs of young members to carry out the defense of the citizens' interests. Unfortunately, at the present day the youth is increasingly skeptical of joining these types of activities. This paper aims to study the social network of young people who are part of the province of Santo Domingo de Tsáchilas, and to identify young people who are natural leaders within the province. For this end, the social networks techniques based on Small World are applied, which are modeled by non-directed graphs, where each vertex represents a person within the social network and each edge the relationship between them. This article also includes the degree of the connection and the presence of indeterminacy in the information. That is why the graphs that model the network are replaced by neutrosophic graphs, where there may be indeterminacy of the connection between at least two vertices. The adjacency matrix of these graphs contains neutrosophic numbers. 17 possible community leaders were identified as a first step in determining whether they could become leaders of the Citizen Participation Council. [ABSTRACT FROM AUTHOR]

In the present work we develop, from a mathematical point of view, the formalization of the molecular fragment contribution to the studied property calculation. A Quantitative Structure-octanol/ water Partition Coefficient Relationship is obtained using values reported in the literature. As molecular descriptors we use the first 15 spectral moments of the Edge Adjacency Matrix (μk). The Edge Adjacency Matrix is weighted in the main diagonal with standard bond dipole moments values. All the spectral moments were calculated by a novel approximation, based in a graph-theoretical substructural analysis and applying the principle of additivity, with the software TOSS-MODE. A lineal model that describes the relation between the studied property and the used molecular descriptors is obtained. Also an analysis of the parameter influence over lipophilicity is done. Further, the group contributions to the partition coefficient are correlated with the Hansch's lipophilic constant φ (r > 0.97). [ABSTRACT FROM AUTHOR]

In Colombia, public policies about quality of higher education involve student assessment systems as a relevant characteristic. These systems should have clear and transparent institutional policies requiring comprehensive identification of attitudinal and academic conditions about examinee performance. Consequently, on the way of continuous improvement of academic services offered by institutions of higher education, an assessment process adequately technified allowing valid inferences about academic achievement is required. In this sense, the Rasch measurement model of Item Response Theory is a modern alternative to strengthen educational measurement estimating the ability of the student and the difficulty of the item on a comparable scale. Unidimensionality, local independence and internal consistency are assumptions made in Rasch measurement model. Unidimensionality assumption has several definitions, one of them is the occurrence of a dominant factor influencing test performance. Another definition is considered in the present study. Here, unidimensionality was interpreted as scalar and criterial homogeneity for the order relations defined by domination for items and assessed applicants. Graph Theory is an ideal mathematical modelling approach to this assumption inasmuch as represent intangible interactions as required. In order to achieve this, Graph Theory and Item Response Theory were combined to examine the qualifying test for the Basic Mathematics subject at Jorge Tadeo Lozano University as a case study. This test was composed by 45 items divided in three blocks. With several combinations of these blocks, three virtual booklets were obtained each one comprising 30 of them. From the application of June 2011, a test sample of 509 responses chains was obtained. Three data bases were processed one for each booklet, the first spanned 175 responses chains, the second 170 and the third one 164. To begin with the exmination on the Rasch measurement model, the parameters reliability, separation, Cronbach Alpha and item residual correlation were estimated to gauge and determine performance test for getting acceptable values in each booklet applied. Tatsuoka was followed to undertake the path to unidimensionality from Graph Theory gathering a real case experience processed with suitable software. Additionally, the sensitivity of the order relation was verified through: 1) ordering by number of correct responses per item (1I order) and items difficulty (2I order); 2) ordering by number of correct responses per applicant (1E order) and estimated ability (2E order). Furthermore, the linear models were obtained collating these orders. In like manner, three Guttman scales and their adjacency matrices were schematized one for each booklet. Subsequently, the respective graphs were processed and represented using Gephi just as a specialized tool that enables running some algorithms like Force Atlas. Afterwards, the second power of each adjacency matrix was found using Matlab 2014b and domination matrices were calculated for both items and applicants in the aforementioned orders for a total of 12 matrices. Consistency index developed by Cliff was computed for the domination matrices. As a result, moderate consistency was observed. Significant domination for the entries of these matrices was analyzed through McNemar test in order to have an asymmetric dominance relation. Moreover, a reachable matrix was calculated for each one of these significant domination matrices as a limit of a sequence of boolean powers. Finally, dominance hierarchies were illustrated with vertex degrees and compared with student maps by the means of Winsteps 3.73. The combination of Graph Theory and Item Response Theory allowed a deeper comprehension of unidimensionality assumption. Thereupon, universities can optimize their resources offering to applicant differential academic options per individual position in the ability scale. The results can be used to outline advantages for the applicants who can evidence their position in the ability scale and identify the different areas to improve. [ABSTRACT FROM AUTHOR]

Copyright of Revista CS is the property of Rafael Silva Vega and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The model for a hydraulic system of a crop with drip irrigation based on directed acyclic graphs and its application on an optimization algorithm in order to find the distribution of an irrigation-fertigation program is proposed. This was done as follows. A crop and its hydraulic network were characterized and represented on a graph. The adjacency matrix was obtained and was transformed into a node and time matrix to be posed as the network model. A program with two functions that used the model found in conjunction with the cuckoo search algorithm was elaborated in order to find a distribution and its corresponding mistake in an irrigation and fertigation sheet. The found distribution was compared with another empirically made distribution. As a result, an efficient model which allows exemplifying the parameters of the hydraulic network, an optimal distribution and a solution to the problem of the irrigation and fertigation programming distribution was obtained. [ABSTRACT FROM AUTHOR]

Copyright of Redes is the property of Redes-Revista Hispana para el Analisis de Redes Sociales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Redes is the property of Redes-Revista Hispana para el Analisis de Redes Sociales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Redes is the property of Redes-Revista Hispana para el Analisis de Redes Sociales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel approach to computer-aided molecular design of antifungal compounds is proposed. The approach Topological Sub Structural Molecular Design (ToSS MoDe) is based on the calculation of the spectral moments of the bond adjacency matrix of graphs representing molecular structures. The spectral moments are expressed as a linear combination of the different structural fragments of the molecular graph. Two series of compounds are possible, one containing antifungal, and the other containing different classes of drugs were used to find a discriminant function with the present approach. Several compounds were identified by the model as antifungal. The critical fragments, active and inactive ones, were detected. The results obtained are interpreted in term of structural features of molecules. The methodology villustrated here permits the rational design of novel compounds with improved activity. [ABSTRACT FROM AUTHOR]

Copyright of Neutrosophic Computing & Machine Learning is the property of Multimedia Larga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista de Psicologia del Trabajo y de Las Organizaciones is the property of Colegio Oficial de Psicologos de Madrid and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Avanzada Científica is the property of Centro de Informacion y Gestion Tecnologica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)