Reservoir design and operation: Effects on aquatic biota-a case study of planktonic copepods

Copepod assemblages from two cascade reservoirs were analyzed during two consecutive years. The upstream reservoir (Chavantes) is a storage system with a high water retention time (WRT of 400 days), and the downstream one (Salto Grande) is a run-of-river system with only 1. 5 days WRT. Copepod composition, richness, abundance, and diversity were correlated with the limnological variables and the hydrological and morphometric features. Standard methods were employed for zooplankton sampling and analysis (vertical 50-μm net hauls and counting under a stereomicroscope). Two hypotheses were postulated and confirmed through the data obtained: (1) compartmentalization is more pronounced in the storage reservoir and determines the differences in the copepod assemblage structure; and (2) the assemblages are more homogeneous in the run-of-river reservoir, where the abundance decreases because of the predominance of washout effects. For both reservoirs, the upstream zone is more distinctive. In addition, in the smaller reservoir the influence of the input from tributaries is stronger (turbid waters). Richness did not differ significantly among seasons, but abundance was higher in the run-of-river reservoir during summer. © 2012 Springer Science+Business Media Dordrecht.

Influence of air abrasion tips and operation modes on enamel-cutting characteristics

Objective: To assess the influence of air abrasion tips and system operation modes on enamel cutting. Methods: Forty bovine teeth were abraded with the air abrasion system Mach 4.1 for 10 and 15 seconds, employing conventional and sonic tips of 0.45-mm inner diameter and a 90° angle, and 27.5-μm aluminum oxide at 5.51 bar air pressure in continuous and pulsed modes. The width and depth of the resulting cuts were measured in SEM. Results: The multivariate analysis of variances revealed that, compared to the sonic tip, the conventional tip produced shallower cuts independent of the operation mode and the application period. Conclusions: The cutting patterns observed in this study suggest that the pulsed mode produced deeper cuts when both the conventional and sonic tips were used, and that the sonic tip cut more dental tissue than the conventional one.

Cooperación entre los países y regiones en desarrollo en el sistema de la CEPAL = Co-operation among developing countries and regions within the ECLA system

Incluye Bibliografía

International economic relations and regional co-operation of Latin America = Las relaciones económicas internacionales y la cooperación regional en América Latina

Includes bibliography

Actividades del sistema de la CEPAL para promover la cooperación entre países y regiones en desarrollo = Activities of the ECLAC system for promoting co-operation among developing countries and regions

Incluye Bibliografía

Informe del Décimo Período de Sesiones del Comité de Desarrollo y Cooperación del Caribe, Puerto España, Trinidad y Tabago, 27 a 29 de octubre de 1987 = Report of the Tenth Session of the Caribbean Development and Co-operation Committee, Port-of-Spain, Trinidad and Tobago, 27-29 October 1987

Contiene resumen de las decisiones y recomendaciones, organizacion del periodo de sesiones, resumen de los documentos, resoluciones adoptadas y lista de participantes.

Actividades del sistema de la CEPAL para promover y apoyar la cooperación entre países y regiones en desarrollo = Activities of the ECLAC system to promote and support co-operation among developing countries and regions

Da cuenta de las principales actividades operacionales realizadas por el sistema de la CEPAL desde el 21 periodo de sesiones de la Comision, especialmente en el marco de su resolucion 486(XXI): Cooperacion tecnica y economica entre paises y regiones en desarrollo.