VOLUMEN 16, NÚMERO 30 (1983-1984)

PROYECTO GEOTÉRMICO CHILES - CERRO NEGRO. Lozano, E.; Cruz, L.ZONAS HIDROGEOLÓGICAS DE COLOMBIA. Lobo-Guerrero, A.ESTUDIO GEOQUÍMICO Y PETROGRÁFICO DE ROCAS SUBVOLCÁNICAS ENTRE LA QUEBRADA CHIRAPOTO Y EL RÍO ARQUÍA (DEPARTAMENTO DE ANTIOQUIA Y CALDAS). Sánchez, L. H.; Parra, R. A.; Ortíz, F.GEOLOGÍA Y EXPERIENCIAS CONSTRUCTIVAS EN EL TÚNEL TUNJITA. Tejada, S. E.CONTRIBUCIÓN AL CONOCIMIENTO DEL PALEOZOICO SUPERIOR EN LA SECCIÓN QUETAME - VILLAVICENCIO. Cortés, R.; De La Espriella, R.TECTÓNICA GRAVITACIONAL EN LA CORDILLERA ORIENTAL AL ESTE DE LA FALLA DE BOYACÁ (DEPARTAMENTO DE BOYACÁ). Reyes, Ch. I.AMBIENTES GEOLÓGICOS URANÍFEROS EN COLOMBIA. Ortega Montero, C

Shells and humans: molluscs and other coastal resources from the earliest human occupations at the Mesolithic shell midden of El Mazo (Asturias, Northern Spain)

Human populations exploited coastal areas with intensity during the Mesolithic in Atlantic Europe, resulting in the accumulation of large shell middens. Northern Spain is one of the most prolific regions, and especially the so-called Asturian area. Large accumulations of shellfish led some scholars to propose the existence of intensification in the exploitation of coastal resources in the region during the Mesolithic. In this paper, shell remains (molluscs, crustaceans and echinoderms) from stratigraphic units 114 and 115 (dated to the early Mesolithic c. 9 kys cal BP) at El Mazo cave (Asturias, northern Spain) were studied in order to establish resource exploitation patterns and environmental conditions. Species representation showed that limpets, top shells and sea urchins were preferentially exploited. One-millimetre mesh screens were crucial in establishing an accurate minimum number of individuals for sea urchins and to determine their importance in exploitation patterns. Environmental conditions deduced from shell assemblages indicated that temperate conditions prevailed at the time of the occupation and the morphology of the coastline was similar to today (rocky exposed shores). Information recovered relating to species representation, collection areas and shell biometry reflected some evidence of intensification (reduced shell size, collection in lower areas of exposed shores, no size selection in some units and species) in the exploitation of coastal resources through time. However, the results suggested the existence of changes in collection strategies and resource management, and periods of intense shell collection may have alternated with times of shell stock recovery throughout the Mesolithic.This research was performed as part of the project “The human response to the global climatic change in a littoral zone: the case of the transition to the Holocene in the Cantabrian coast (10,000–5000 cal BC) (HAR2010-22115-C02-01)” funded by the Spanish Ministry of Economy and Competitiveness. AGE was funded by the University of Cantabria through a predoctoral grant and IGZ was funded by the Spanish Ministry of Economy and Competitiveness through a Juan de la Cierva grant. We also would like to thank the University of Cantabria and the IIIPC for providing support, David Cuenca-Solana, Alejandro García Moreno and Lucia Agudo Pérez for their help. We also thank Jennifer Jones for correcting the English. Comments from two anonymous reviewers helped to improve the paper

The Fifteenth Data Release of the Sloan Digital Sky Surveys: First Release of MaNGA-derived Quantities, Data Visualization Tools, and Stellar Library

Twenty years have passed since first light for the Sloan Digital Sky Survey (SDSS). Here, we release data taken by the fourth phase of SDSS (SDSS-IV) across its first three years of operation (2014 July–2017 July). This is the third data release for SDSS-IV, and the 15th from SDSS (Data Release Fifteen; DR15). New data come from MaNGA—we release 4824 data cubes, as well as the first stellar spectra in the MaNGA Stellar Library (MaStar), the first set of survey-supported analysis products (e.g., stellar and gas kinematics, emission-line and other maps) from the MaNGA Data Analysis Pipeline, and a new data visualization and access tool we call "Marvin." The next data release, DR16, will include new data from both APOGEE-2 and eBOSS; those surveys release no new data here, but we document updates and corrections to their data processing pipelines. The release is cumulative; it also includes the most recent reductions and calibrations of all data taken by SDSS since first light. In this paper, we describe the location and format of the data and tools and cite technical references describing how it was obtained and processed. The SDSS website (www.sdss.org) has also been updated, providing links to data downloads, tutorials, and examples of data use. Although SDSS-IV will continue to collect astronomical data until 2020, and will be followed by SDSS-V (2020–2025), we end this paper by describing plans to ensure the sustainability of the SDSS data archive for many years beyond the collection of data

The Fifteenth Data Release of the Sloan Digital Sky Surveys: First Release of MaNGA-derived Quantities, Data Visualization Tools, and Stellar Library

Twenty years have passed since first light for the Sloan Digital Sky Survey (SDSS). Here, we release data taken by the fourth phase of SDSS (SDSS-IV) across its first three years of operation (2014 July–2017 July). This is the third data release for SDSS-IV, and the 15th from SDSS (Data Release Fifteen; DR15). New data come from MaNGA—we release 4824 data cubes, as well as the first stellar spectra in the MaNGA Stellar Library (MaStar), the first set of survey-supported analysis products (e.g., stellar and gas kinematics, emission-line and other maps) from the MaNGA Data Analysis Pipeline, and a new data visualization and access tool we call "Marvin." The next data release, DR16, will include new data from both APOGEE-2 and eBOSS; those surveys release no new data here, but we document updates and corrections to their data processing pipelines. The release is cumulative; it also includes the most recent reductions and calibrations of all data taken by SDSS since first light. In this paper, we describe the location and format of the data and tools and cite technical references describing how it was obtained and processed. The SDSS website (www.sdss.org) has also been updated, providing links to data downloads, tutorials, and examples of data use. Although SDSS-IV will continue to collect astronomical data until 2020, and will be followed by SDSS-V (2020–2025), we end this paper by describing plans to ensure the sustainability of the SDSS data archive for many years beyond the collection of data

Effect of Urea on Synthesis of Ceramics Materials by the Modified Combustion Method

The proportion of urea in the modified combustion method to prepare lithium metasilicate (Li₂SiO₃) powders was investigated. Reactions were performed using LiOH:H₂SiO₃:CH₄N₂O in molar ratios of 1:1:1, 1:1:2, 1:1:3, 1:1:4 and 1:1:5 which were heated at 450°C during 5 min. It was found, by X-ray diffraction, that LiOH:H₂SiO₃:CH₄N₂O in the ratio of 1:1:3 was the more adequate molar ratio to produce mainly Li₂SiO₃. It was observed that excess of urea produced mainly silicium dioxide (SiO₂) in coesite phase instead Li₂SiO₃. Thermogravimetric analyses showed that decomposition products of urea, such as biuret, cyanic acid and cyanuric acid, were found in samples prepared with high proportions of urea (1:1:4 and 1:1:5). Carbonates identified by IR spectroscopy were found in samples prepared with LiOH:H₂SiO₃:CH₄N₂O in 1:1:1, 1:1:2, 1:1:3, 1:1:14 and 1:1:5 molar ratios

Ciencia y tecnología (No. 2 segunda época sep 2008)

Publicación Bianual de la Dirección de Investigación Científica de la Universidad Nacional Autónoma de Honduras.Contenido: Tema central: El agua en Honduras: diagnóstico y perspectivas. Comportamiento de los sedimentos fluviales en Honduras. Rendimiento y pérdida de suelo. Zona central y oriental / Roberto Fredy Ávalos Lingan 3. Análisis de la contaminación del Río Choluteca y sus efectos sobre la población / Beatriz Ponce de Montoya 19. Recursos hídricos, contaminación y sociedad civil en la región occidental de Honduras / Jorge Humberto Orellana, Francisco Machado Leiva, Álvaro Rivas Guzmán 38. Diálogo abierto: Entrevista a Rodolfo Ochoa Álvarez "El manejo del agua en Honduras" 53. Diversidad temática. Del sexo a la rosa: erotismo en la poesía de Clementina Suarez / Clauda Torres 63. Proyecto de generación de energía eléctrica en base a biomasa aplicado a la UNAH / Roberto Ortíz, Osman Mejía, Jairo Sabillón, Dennis A. Rivera 74. Vínculo estrategia de operaciones-tecnología en la industria hondureña: ajuste de selección / César H. Ortega Jiménez 91. Registro de un nuevo helecho para la flora de Honduras / Ruth Karina Hernández Cibrian, Cyril Hardy Nelson Sutherland 110. Modelo numérico de movimiento ondulatorio en un medio heterogéneo no isotrópico bajo condiciones de estabilidad orbital / Fredy Vides 114. Notas informativas. Criterios para la publicación en la Revista Ciencia y Tecnología 145