RESUMO

Melipona quadrifasciata anthidioides is a species of stingless bee popularly known in Brazil as "mandaçaia". Products derived from bees for food and therapeutic uses, have stimulated the evaluation of the chemical composition of geopropolis. Concentrations of 24 essential and potentially toxic elements were determined in geopropolis samples, using a sequential optical emission spectrometer with inductively coupled plasma (ICP OES) after microwave-assisted acid digestion. Principal component analysis (PCA) and Hierarchical cluster analysis (HCA) were used to carry out an exploratory analysis of the samples. The following elements were quantified (in mg Kg-1): Al (320,414.40-36,911.1), As (

Assuntos

RESUMO

The present work aimed to analyze the mineral nutrition of Physalis angulata L. under stress by aluminum in the nutrient solution. The treatments consisted of five different concentrations of aluminum in the nutrient solution (0, 0.04, 0.08, 0.12, and 0.16 mmol L-1) in the AlCl3 form. The plants were exposed to Al for 30 days. Subsequently, nutritional and aluminum analyses were performed on plant tissue. The data were submitted to analysis of variance (p < 0.05), and, in case of significance, the regression study was performed as well as hierarchical cluster analysis (HCA) and principal component analysis (PCA) were used. The formation of four groups occurred, where we can observe the similarity and differences in the treatments between them. The separation of the treatments into groups reflected the heterogeneity of the treatments about the aluminum levels in the nutrient solution, evidencing its phytotoxicity level in Physalis angulata plants. Among the analyzed variables, P, K, Ca, Mg, Fe, Mo, and Zn were the most influential ones demonstrated by principal component analysis (PCA). The stress of 0.16 mmol L-1 of Al increased the phosphorus contents in the stems and roots and the potassium, copper, and molybdenum contents in all parts of the plants. In contrast, Al reduced the levels of calcium, magnesium, iron, and zinc in P. angulata plants. Iron being the micronutrient that showed the largest reduction, followed by zinc in the leaves. The highest levels of aluminum were found in the roots.

Assuntos

RESUMO

This article investigates sediments collected from the banks of the Subaé River located in Todos os Santos Bay in the state of Bahia, Brazil, in 2018, twenty-five years after the closing of a former lead alloy processing plant. Ten sediment samples were collected at different points of the course of the river and its estuarine region. Chemometric tools were used to determine geochemical correlations between the organic matter content and concentration of sulfides and potentially toxic metals. The inorganic geochemical variables (enrichment factor [EF]) used in this evaluation were concentrations of the Pb, Cd, Cu, Zn, and Ni. Chemical element analyses were performed using ICP-OES. To assess the interaction between metals and sulfide or metals and organic matter, concentrations of Pb, Cd, Cu, Zn, Ni, sulfide, and the silt-clay fraction constituted the organic geochemical parameters selected to characterize the amount of organic matter present in Subaé River sediment samples, determining the carbon content (%TOC) to compose the matrix of the principal component analysis (PCA) and hierarchical cluster analysis. PCA showed that 88.3% of the samples were representative for assessing correlations between geochemical variables. A tendency toward binding was found among Cu, Cd, Ni, and sulfide, as well as the silt-clay fraction. The concentrations (mg kg-1) of lead, zinc, and copper were higher in both collection campaigns, ranging from 4.72 to 31.34, 12.76 to 54.24, and 5.34 to 31.37, respectively. Pb and Zn were presented in elemental form when assessed as a function of the pH and Eh of the environment. Except for Cd (EF: 0.51 to 5.49), the other elements exhibited little or no potential pollution in the aquatic environment of the Subaé River.

Assuntos

RESUMO

In Argentina, vinegars are cheap agro-food products without exhaustive regulation and the production of high-quality vinegars has not been exploited yet. In fact, Argentinean vinegars have not been studied. In this context, a first study of Argentinean balsamic and wine vinegars was carried out by a sensory and spectroscopic characterization and by a comparison with well-recognized European vinegars. For that, ultraviolet-visible and fluorescence spectroscopies were applied together with principal component analysis (PCA) and parallel factor analysis (PARAFAC) performed on each data set, respectively. Results showed differences between acetification processes, origin countries and a wide variability within Argentinean production. The sensory characterization on Argentinean wine vinegars was performed by triangular and ordering preference tests showing statistically significant preferences toward the traditional and the rapid vinegars. This work highlights the effect of production on quality in order to provide added value to the Argentinean vinegars.

RESUMO

Once the collection of data from a study has been completed and the respective database is available, the researcher is often impatient to answer the research question and ventures into the final steps of the analysis. However, a key stage, prior to a more complex or sophisticated statistical analysis, is data exploration and descriptive statistics. Unfortunately, the exploratory analysis of the data is often performed without much dedication, or is simply "skipped", which can have important consequences on the results obtained and lead to the report of erroneous conclusions. On the one hand, exploration allows to detect errors in the data and, if possible, to correct them from the source of origin or take them into account to make decisions about what to do with them. On the other hand, exploration allows to know the behavior of the variables evaluated in terms of their distribution (key concept in Statistics) and possible relationships among them, which is essential for subsequent descriptive and inferential analysis. The objective of this article is to show graphic tools for the exploration of quantitative data, in order to visualize its distribution and compare groups according to categories of qualitative variables.

Una vez finalizada la recolección de datos de un estudio y contado con la respectiva base de datos, es frecuente que el investigador esté impaciente por responder a la pregunta de investigación y se aventure a realizar los pasos finales del análisis. No obstante, una etapa clave, previa a un análisis estadístico más complejo o sofisticado, es la exploración de datos y la estadística descriptiva. Lamentablemente, el análisis exploratorio de los datos muchas veces es realizado sin mucha dedicación, o simplemente es "saltado", lo que puede tener consecuencias importantes en los resultados obtenidos y conducir al reporte de conclusiones erróneas. Por un lado, la exploración permite detectar errores en los datos y, si es posible, corregirlos desde la fuente de origen o tenerlos en cuenta para tomar decisiones respecto a qué hacer con ellos. Por otra parte, la exploración permite conocer el comportamiento de las variables evaluadas en términos de su distribución (concepto clave en Estadística) y posibles relaciones entre ellas, lo cual es fundamental para los análisis descriptivo e inferencial posteriores. El objetivo de este artículo es mostrar herramientas gráficas para la exploración de datos cuantitativos, con el fin de visualizar su distribución y comparar grupos según categorías de variables cualitativas.

Assuntos

RESUMO

Resumen Introducción. La educación se ha consolidado como estrategia que promueve el desarrollo del conocimiento y la formación de las comunidades y la formación avanzada constituye el medio para incrementar el capital intelectual de las sociedades. Objetivo. Identificar las principales motivaciones que tienen los estudiantes universitarios para continuar un proceso de formación avanzada en instituciones de Educación Superior. Metodología. Aplicación de un cuestionario auto-administrado a 728 estudiantes universitarios, de séptimo semestre en adelante, de la ciudad de Medellín. Se exploraron siete dimensiones relacionadas con la motivación para continuar sus estudios. Resultados. Se destacan factores motivacionales por parte de los estudiantes como la exigencia académica y las modalidades presenciales de la oferta académica para continuar con su proceso de formación avanzada. Conclusiones. Las Instituciones de Educación Superior deben considerar el contexto social en el que se enmarcan, así como sus propósitos fundacionales, para responder de manera adecuada a las necesidades de formación avanzada que se requiere en sus entornos.

Abstract Introduction. Education has been consolidated as a strategy to promote the development of knowledge and community vocational training; and the advanced academic degrees as the way to rise the intellectual capital in the society. Objective. Through an exploratory analysis, we try to identify the main undergraduate students motivations to enroll in a graduate program. Methodology. We applied a self-application questionnaire to 728 undergraduate students in the last semesters of their vocational training, at Medellin-Colombia. We explored seven dimensions related to the motivations to study a graduate program. Results. The undergraduate students' motivations to enroll in a graduate program are influenced by academic high level offered and traditional education (non-virtual) methodology of the advanced academic degrees. Conclusions. The Higher Education Institutions have to consider the social context in which they are inmerse, besides their foundational principles, to response effectively to the needed from people to enroll in graduate programs.

Resumo Introdução. A educação foi consolidada como uma estratégia que promove o desenvolvimento do conhecimento e a formação de comunidades, e o treinamento avançado é o meio para aumentar o capital intelectual das sociedades. Objetivo. Identificar, através de uma análise exploratória, as principais motivações que os estudantes universitários têm para continuar um processo de treinamento avançado em instituições de ensino superior. Metodologia. Aplicação de um questionário autoadministrado a 728 estudantes universitários, a partir do sétimo semestre, da cidade de Medellín. Foram exploradas sete dimensões relacionadas à motivação para continuar seus estudos. Resultados. Os fatores motivacionais por parte dos alunos, como o requisito académico e as modalidades face a face da oferta académica, são destacados para continuar com seu processo de treinamento avançado. Conclusões. As instituições de ensino superior devem considerar o contexto social em que são enquadradas, bem como seus objetivos fundamentais, para responder adequadamente às necessidades de treinamento avançado exigido em seus ambientes.

RESUMO

Brain research typically requires large amounts of data from different sources, and often of different nature. The use of different software tools adapted to the nature of each data source can make research work cumbersome and time consuming. It follows that data is not often used to its fullest potential thus limiting exploratory analysis. This paper presents an ancillary software tool called BRAVIZ that integrates interactive visualization with real-time statistical analyses, facilitating access to multi-facetted neuroscience data and automating many cumbersome and error-prone tasks required to explore such data. Rather than relying on abstract numerical indicators, BRAVIZ emphasizes brain images as the main object of the analysis process of individuals or groups. BRAVIZ facilitates exploration of trends or relationships to gain an integrated view of the phenomena studied, thus motivating discovery of new hypotheses. A case study is presented that incorporates brain structure and function outcomes together with different types of clinical data.

RESUMO

En este trabajo se presenta un estudio exploratorio sobre las características psicométricas de un instrumento sobre el control de de la vida personal, analizando su estructura factorial mediante un análisis exploratorio y confirmatorio de sus dimensiones. El tamaño del estudio final fue de 8.504 entrevistas y el criterio básico de estratificación fue el distrito municipal en 21 estratos. Los resultados encontrados señalan que los ítems en cada una de las dimensiones y sus pesos factoriales son aceptables y se relacionan con enunciados genéricos sobre la atribución de control. A su vez, los índices de bondad de ajuste encontrados de cada uno de los modelos propuestos, arrojan información interesante sobre las posibilidades que este cuestionario ofrece.

The purpose of this study was to examine the characteristics psychometrics of a scale on the control of the personal life, analyzing its factorial structure by means of an exploratory and confirmatory analysis of its dimensions. The size of the final study was 8.504 interviews and the basic criterion was of stratification was the municipal district in 21 strata. The results indicate that the items in each of the dimensions and his weight factorials are acceptable and are related to generic terms of reference on the attribution of control. Also, the opposing indexes of goodness of fit of each one of the proposed models, throw interesting information about the possibilities that this scale offers.

Assuntos