Grain size of marine sediments in the environmental studies, from sampling to measuring and classifying. A critical review of the most used procedures

The knowledge of sediment texture is a main issue in the marine environmental research. Studies on sediment contamination, ecology of benthic communities, seismic studies, remote sensing surveys and beach nourishment are among the research areas which benefit of information on sediment grain size. In this review, the main methods used for sampling, measuring and classifying marine sediments are critically illustrated in order to highlight their strengths and weaknesses. From this revision it was deduced that it does not exists a single procedure, considered as the best one, to be applied in all the cases for obtaining reliable grain size data. This result can be achieved using as much as possible flexible strategies, and adopting the suitable sampling devices and analytical instruments based on the overall characteristics of the study area and the specific aim of the survey

Evaluación de aprendizaje y logro de capacidades adquiridas durante la formación profesional de los estudiantes de la Universidad Nacional Daniel Alcides Carrión, 2018

El propósito de la investigación fue determinar cómo realizan los docentes la evaluación de aprendizaje para identificar las capacidades que adquieren los estudiantes durante su formación profesional. Se realizo un estudio descriptivo con diseño transversal. La muestra fue de 20 profesores y 100 estudiantes de la Escuela Profesional de Educación Secundaria de la Facultad de Ciencias de la Educación de la Universidad Nacional Daniel Alcides Carrión de Perú, en el año 2018. Los resultados arrojaron que los docentes realizan la evaluación de aprendizaje a través de parciales de manera permanente, haciendo uso de un registro de notas, otros con el registro auxiliar, y las pruebas escritas tipo cuestionario, seguido de exposición y entrega de trabajos, y de los estudiantes encuestados manifiestan que el 58% SI logran las capacidades, sin embargo hay necesidad de mejorar y es muy prematuro describir las capacidades adquiridas de los estudiantes ya que las actividades realizadas para recolectar y valorar la información no permiten dar a conocer las capacidades programadas y dar seguimiento para la mejora continua y así crear un sistema de evaluación

Analysis of a large Next Generation Sequencing dataset for malaria epidemiology investigations

Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected female Anopheles mosquitoes. Nearly half of the world's population is at risk of malaria. Understanding how malaria parasites spread and evolve is a key step in eradicating the disease. The goal of this thesis work is to develop and test bioinformatics tools that allow an effective data analysis that responds to the control needs of useful information from the epidemiological point of view of malaria. A dataset of Next Generation Sequencing (NGS) data resulting from the sequencing of a set of samples collected in Burkina Faso was used. The informations that can be extrapolated according to the epidemiological context are useful for planning and evaluating control programs. Obtaining this information from NGS data is not trivial as there is no obvious or standardized bioinformatics analysis pipeline and there are a whole series of choices and methodological proposals that must be made starting from the organization of the data

The Black Girl and Moolaadè. Which Africa and teories do the lens of Ousmane Sembène show us?

A sugestão dos filmes A Negra de... e Moolaadè do cineasta senegalês Ousmane Sembène foi pensada no sentido de propor o conhecimento do cinema africano. A intenção aqui é aprender a olhar a África e suas histórias sob a lente de um diretor africano e as teorias que subjazem no interior das narrativas fílmicas

Grain size analysis. A comparison between laser granulometer and sedigraph

A total of 24 sediment samples from 5 different Italian marine sites (4 from Tyrrhenian Sea and 1 from Adriatic Sea) were analyzed for grain size using two different instruments: Laser Granulometer (LG) and X-ray Sedigraph (XS). The analysis was carried out exclusively on the fine fraction (<63 m), obtained by dry sieving, in order to compare data results and highlight potential differences. The results show an increase of 15-25% of clay content in the samples analyzed by XS with respect to the ones analyzed by LG. In spite of analyzing the <63 m fraction, both instruments recorded the presence of variable amount of sand in most samples, with high percentages (up to 53.3% for XS and 30% for LG) in the Bagnoli samples. The different results supplied by the two instruments may be attributed to the different principles of functioning of the two instruments and to the peculiar physical properties of the particles such as shape, density and mineralogical composition

Differences in acquisition of environmental data in strongly impacted marine sediments using gravity and vibro corers: the case-study of Augusta harbor (Eastern Sicily, Italy)

Sediment cores are used to reconstruct the chronological evolution of contamination in impacted areas while deep core levels may be considered as reference conditions for the assessment of environmental status. For this purpose, the collection of undisturbed cores is essential. Vibro and gravity corers are the most used devices for environmental research. In this study, chemical (Ba, Hg and PCBs) and grain size data obtained by means of gravity (SW-104) and vibro (Rossfelder®) corer from 3 stations of the heavily contaminated Augusta harbor (Sicily, Italy) were considered. Their vertical profiles were compared considering the different technical characteristics of corers, in order to highlight differences in data acquisition. Results showed that, for areas characterized by high sedimentation rates, the vibrocorer is the best choice for the higher penetration capacity. No significant differences were recognized for sediment compaction and potential downward drag of the contaminants.</p

A comparison between Laser Granulometer and Sedigraph in grain size analysis of marine sediments

A total of 24 sediment samples with wide dimensional, mineralogical and compositional range were considered, collected from 5 Italian coastal marine sites. The fine fraction (<63 μm) was analyzed using Laser Granulometer (LG) and X-ray Sedigraph (XS) in order to compare data and highlight potential differences. The unexpected variable sandy fraction in nearly all the samples was attributed to clay mineral aggregates. The highest sand percentages detected by XS were attributed to local compositional sediment features. An increase of 15–25% of clay in samples analyzed by XS was attributed to the different working principles of the considered devices. Nevertheless, final results succeeded in characterizing sediment texture and distribution as a function of water depth. In conclusion, it's important to select the analytical instrument according to the characteristics of sediments, to adjust the density of media solution for XS analysis, and to prevent aggregates formation for both XS and LG

The marine sedimentary record of natural and anthropogenic contribution from the Sulcis-Iglesiente mining district (Sardinia, Italy)

Intensive exploitation of base metal deposits in the Sulcis-Iglesiente district (Sardinia, Italy), lasted from the 1850s to the 1990s, determined a high environmental impact on the coastal area, but the effects on marine environment have never been investigated. A marine sediment core, dated with14C, was characterized for grain size, chemical and mineralogical composition, in order to reconstruct the sedimentary history of the area and to assess the environmental impact of mining. The comparison of chemical and mineralogical characteristics of recent sediments with those of pre-industrial age allowed discriminating the real anthropogenic impact from the natural metal enrichment. The correspondence, in the upper core, of anthropogenic trace metal enrichment with the presence of mine waste minerals is attributed to the exploiting over industrial scale; the still high metal enrichment in sediment surface levels suggests a still existing impact due to mine dumps and tailings weathering