UNIVERSITA JOURNAL 2020-03-24T00:22:19+00:00 Dr. Leonardo Mendoza. Open Journal Systems <p align="justify"><strong>Universitas (León)</strong>, the scientific journal of the UNAN-León, is constituted as the official organ of dissemination of the research of the university by means of electronic and written. Attached, directed and coordinated by the Vice-Rector for Research, Postgraduate and Social Projection and fulfilling its institutional mission, which promotes, manages and coordinates the dissemination and transfer of the results of research activities carried out by university academics. The magazine was created under the Rector's Office of Dr. Rigoberto Sampson Granera, through Rectorial Agreement No. 4, dated November 16, 2007.</p> Tilapia culture and phytoplankton species associated with Tilapias aquaculture 2020-03-24T00:22:18+00:00 Carmen Hernández Evenor Martínez Guillermo Díaz Haymenrique Prieto <p><span class="fontstyle0">The need to know how microalgae concentrations fluctuate in tilapias cultures is crucial since these animals are mostly herviboros and microalgae<br>represent a main part of their diet. Therefore, it sought to identify and classify the diversity of phytoplankton species associated with Tilapias cultivation.<br>The phytoplankton samples were identified with a gender level and the population density (Cel / ml) was estimated. During the study period the<br>phytoplankton community was represented by the following taxonomic divisions that are: chlorophytes, Diatoms, Cyanophytes, without being<br>Dinoflagellates, standing out the species of chlorophytes in all the samplings. Three crop ponds were used, samples were taken every 4 days between<br>11 am and 1 pm. The results obtained in the research are as follows: in pond 1 it was found that the oxygen level ranged from 1.1 mg / L to 4.7 mg / L;<br>in pond 2 between 1.16 mg / L and 3.8 mg / L and the pond 3 between 1.15 mg / L and 3.6 mg / l. As for the temperature in pond 1, a fluctuation<br>between 28.4 ° C and 33.6 ° C, pond 2, between 27.5 ° C and 33.3 ° C, for pond 3, between the 28 ° C and 33.4 ° C, as for pH, pond 1 recorded a pH<br>of 7.8 and 10.6, for pond 2 of 7.2 and 11 having the highest value between each of ponds, for pond 3 of 7.8 And 10, 3. The highest growth of algae in</span></p> 2016-06-30T00:00:00+00:00 ##submission.copyrightStatement## Chemical composition and physical properties of geothermal fluids of the San Cristobal volcanic complex - Casita Nicaragua 2020-03-24T00:22:19+00:00 Jorge Cisne Arnoldo Ferrufino Haylell López Julio Álvarez Martha Ibarra <p>The San Cristóbal volcano is the highest and one of the most active volcanoes in Nicaragua. It is located in the Volcanic Complex that bears its name and includes five volcanic structures: San Cristóbal, Casitas, Chonco, oyotepe and La Pelona. San Cristóbal is the most active of the group. It emits gases continuously and from time to time there is seismic activity around it. In the present study, a sample of waters around the volcanic building that had some hydrothermal alterations (temperatures above room temperature) was carried out, after the analysis of the samples it was observed that the water samples had a pH of 6.5 slightly acidic and Temperatures on average of 50 ° C in two of the three studied sites, on the other hand, were characterized the waters studied as of meteoric origin shallow convectively heated by a source of magmatic origin this due to their high concentrations of bicarbonates which Oscillate between 140 and 350 mg / kg evidenced in the ternary and Pipper diagrams.</p> 2016-06-30T00:00:00+00:00 ##submission.copyrightStatement## Uso de la Realidad Aumentada como medio didáctico para el componente curricular de Reparación y Mantenimiento de Computadoras impartido en las carreras ofrecidas por el Departamento de Computación de la UNAN-León 2020-03-24T00:22:19+00:00 Julio González Jairo Mayorga Wiston Mendoza Juan Midece <p>The article presents the use of the Augmented Reality (RA) technology as a didactic tool for the curriculum component of Computer Repair and Maintenance, which is taught in the courses offered by the UNAN-León Computer Department. This was designed and developed an application for mobile devices with Android platform in conjunction with a printed graphic medium of the magazine type. The main idea is that the student uses, together with the application, the mobile device and the camera of the device, the printed magazine to be placed on top of the marks indicating the presence of content with Augmented Reality; The contents shown with the Augmented Reality enrich even more the information provided by the magazine itself, showing: videos, images, texts, textures in third dimension, etc. Allowing to capture the student's interest in the contents shown. A graphic medium is used because it is a didactic tool of support that illustrates in an attractive way the subjects to be approached in conjunction with the use of the Augmented Reality, offering to the student an interaction with virtual elements in real time superposing them in images denominated markers. The application is developed using the Unity 3D graphics engine which integrates the development environment MonoDevelop, which allows working with a variant of the CSharp programming language, all using the development kit for Augmented Reality offered by Qualcomm Vuforia SDK.</p> <p><strong>&nbsp;</strong></p> 2016-06-30T00:00:00+00:00 ##submission.copyrightStatement## Influencia del manejo silvicultural en la producción de madera rolliza y leña de Eucalyptus camaldulensis: estudios de casos de 17b plantaciones bajo sistemas de manejo de rebrotes en la comunidad Cristo Rey, Quezalguaque, Nicaragua 2020-03-24T00:22:19+00:00 Margarita Nieto Roger Villalobos Adriana Escobedo Andrea Jhonson Iván Soto Daniel Paredes <p>The present study analyzes the management of eucalyptus plantations given by the producers. The research started in 2013 by the Finnfor project which established 17 permanent monitoring plots grouped into 4 categories based on the potential for production of roundwood. The same growth, utilization and sanitation variables were followed up, as well as the performance of the plots and possible lessons from the plots. Among the results obtained are that the first use is given at 3 years (alfajillas and some soleras) later manage the regrowth and thin each 6 or 8 months. This is selective (2 to 3 cuts / year) or clear cut (4 or 6 years) and every year they give maintenance to the property (plantation). The growth, height, diameter and basal area were within the ranges cited by the literature. Based on interviews with producers and financial analysis, selective cutting is more effective and profitable. The largest volume (measured in 2015) was plot 13 with 51 m3 / ha in which 2 shoots / stump were handled and the average height of the stumps ranged between 5 cm and 17 cm.</p> 2016-06-30T00:00:00+00:00 ##submission.copyrightStatement##