Producción primaria y la estimación del rendimiento potencial pesquero en el Lago Cocibolca, Nicaragua

Once mediciones de la producción primaria utilizando el método de C14 se realizaron entre los años 1990 y 1998 en el Lago Cocibolca. La producción primaria varió entre 0.5 y 3.1 g C m-2 d-1, registrando los valores promedios más altos durante la estación seca, en comparación con la época de lluvias, con 2.4 y 1.2 g C m-2 d-1, respectivamente. Estas diferencias probablemente se deban a las variaciones en las condiciones hidrográficas, especialmente las relacionadas con el régimen de lluvias de la región. Las diatomeas dominaron durante la estación seca, mientras que, las cianófitas y clorófitas abundaron en número y biomasa durante los meses de mayor precipitación y estabilidad en la columna de agua. La fracción de la Radiación Fotosintéticamente Activa (PAR), absorbida por el fitoplancton fue muy similar en ambas estaciones. Los valores de producción primaria en el Lago Cocibolca y considerando además, el limitado número de datos de nutrientes, lo ubican como un lago eutrófico en la escala trófica. El rendimiento potencial pesquero, estimado por métodos indirectos, es de 50-70 kg ha-1 a-1

ExploreASL: an image processing pipeline for multi-center ASL perfusion MRI studies

Arterial spin labeling (ASL) has undergone significant development since its inception, with a focus on improving standardization and reproducibility of its acquisition and quantification. In a community-wide effort towards robust and reproducible clinical ASL image processing, we developed the software package ExploreASL, allowing standardized analyses across centers and scanners. The procedures used in ExploreASL capitalize on published image processing advancements and address the challenges of multi-center datasets with scanner-specific processing and artifact reduction to limit patient exclusion. ExploreASL is self-contained, written in MATLAB and based on Statistical Parameter Mapping (SPM) and runs on multiple operating systems. To facilitate collaboration and data-exchange, the toolbox follows several standards and recommendations for data structure, provenance, and best analysis practice. ExploreASL was iteratively refined and tested in the analysis of >10,000 ASL scans using different pulse-sequences in a variety of clinical populations, resulting in four processing modules: Import, Structural, ASL, and Population that perform tasks, respectively, for data curation, structural and ASL image processing and quality control, and finally preparing the results for statistical analyses on both single-subject and group level. We illustrate ExploreASL processing results from three cohorts: perinatally HIV-infected children, healthy adults, and elderly at risk for neurodegenerative disease. We show the reproducibility for each cohort when processed at different centers with different operating systems and MATLAB versions, and its effects on the quantification of gray matter cerebral blood flow. ExploreASL facilitates the standardization of image processing and quality control, allowing the pooling of cohorts which may increase statistical power and discover between-group perfusion differences. Ultimately, this workflow may advance ASL for wider adoption in clinical studies, trials, and practice