Emerging insights from the evolving framework of structural abstraction

Only recently ‘abstraction from objects’ has attracted attention in the literature as a form of abstraction that has the potential to take account of the complexity of students’ knowing and learning processes compatible with their strategy of giving meaning. This paper draws attention to several emerging insights from the evolving framework of structural abstraction in students’ knowing and learning of the limit concept of a sequence. Particular ideas are accentuated that we need to understand from a theoretical point of view since they reveal a new way of understanding knowing and learning advanced mathematical concepts

Cognitive processes underlying mathematical concept construction: The missing process of structural abstraction

The purpose of this paper is twofold: On the one hand, this work frames a variety of considerations on cognitive processes underlying mathematical concept construction in two research strands, namely an actions-first strand and an objects-first strand, that mainly shapes past and current approaches on abstraction in learning mathematics. This classification provides the identification of an often overlooked fundamental cognitive process, namely structural abstraction. On the other hand, this work shows a theory-driven and research-based approach illuminating the hidden architecture of cognitive processes involved in structural abstraction that gives new insights into an integrated framework on abstraction in learning mathematics. Based on our findings in empirical investigations, the paper outlines a theoretical framework on the cognitive processes taking place on mental (rather than physical) objects

Images of abstraction in mathematics education: Contradictions, controversies, and convergences

In this paper we offer a critical reflection of the mathematics education literature on abstraction. We explore several explicit or implicit basic orientations, or what we call images, about abstraction in knowing and learning mathematics. Our reflection is intended to provide readers with an organized way to discern the contradictions, controversies, and convergences concerning the many images of abstraction. Given the complexity and multidimensionality of the notion of abstraction, we argue that seemingly conflicting views become alternatives to be explored rather than competitors to be eliminated. We suggest considering abstraction as a constructive process that characterizes the development of mathematical thinking and learning and accounts for the contextuality of students’ ideas by acknowledging knowledge as a complex system

Identification of a biomarker panel for improvement of prostate cancer diagnosis by volatile metabolic profiling of urine

Background: The lack of sensitive and specific biomarkers for the early detection of prostate cancer (PCa) is a major hurdle to improve patient management. Methods: A metabolomics approach based on GC-MS was used to investigate the performance of volatile organic compounds (VOCs) in general and, more specifically, volatile carbonyl compounds (VCCs) present in urine as potential markers for PCa detection. Results: Results showed that PCa patients (n = 40) can be differentiated from cancer-free subjects (n = 42) based on their urinary volatile profile in both VOCs and VCCs models, unveiling significant differences in the levels of several metabolites. The models constructed were further validated using an external validation set (n = 18 PCa and n = 18 controls) to evaluate sensitivity, specificity and accuracy of the urinary volatile profile to discriminate PCa from controls. The VOCs model disclosed 78% sensitivity, 94% specificity and 86% accuracy, whereas the VCCs model achieved the same sensitivity, a specificity of 100% and an accuracy of 89%. Our findings unveil a panel of 6 volatile compounds significantly altered in PCa patients' urine samples that was able to identify PCa, with a sensitivity of 89%, specificity of 83%, and accuracy of 86%. Conclusions: It is disclosed a biomarker panel with potential to be used as a non-invasive diagnostic tool for PCa.info:eu-repo/semantics/publishedVersio

Genome of Herbaspirillum seropedicae Strain SmR1, a Specialized Diazotrophic Endophyte of Tropical Grasses

The molecular mechanisms of plant recognition, colonization, and nutrient exchange between diazotrophic endophytes and plants are scarcely known. Herbaspirillum seropedicae is an endophytic bacterium capable of colonizing intercellular spaces of grasses such as rice and sugar cane. The genome of H. seropedicae strain SmR1 was sequenced and annotated by The Paraná State Genome Programme—GENOPAR. The genome is composed of a circular chromosome of 5,513,887 bp and contains a total of 4,804 genes. The genome sequence revealed that H. seropedicae is a highly versatile microorganism with capacity to metabolize a wide range of carbon and nitrogen sources and with possession of four distinct terminal oxidases. The genome contains a multitude of protein secretion systems, including type I, type II, type III, type V, and type VI secretion systems, and type IV pili, suggesting a high potential to interact with host plants. H. seropedicae is able to synthesize indole acetic acid as reflected by the four IAA biosynthetic pathways present. A gene coding for ACC deaminase, which may be involved in modulating the associated plant ethylene-signaling pathway, is also present. Genes for hemagglutinins/hemolysins/adhesins were found and may play a role in plant cell surface adhesion. These features may endow H. seropedicae with the ability to establish an endophytic life-style in a large number of plant species

Mucopolysaccharidosis I, II, and VI: Brief review and guidelines for treatment

Mucopolysaccharidoses (MPS) are rare genetic diseases caused by the deficiency of one of the lysosomal enzymes involved in the glycosaminoglycan (GAG) breakdown pathway. This metabolic block leads to the accumulation of GAG in various organs and tissues of the affected patients, resulting in a multisystemic clinical picture, sometimes including cognitive impairment. Until the beginning of the XXI century, treatment was mainly supportive. Bone marrow transplantation improved the natural course of the disease in some types of MPS, but the morbidity and mortality restricted its use to selected cases. The identification of the genes involved, the new molecular biology tools and the availability of animal models made it possible to develop specific enzyme replacement therapies (ERT) for these diseases. At present, a great number of Brazilian medical centers from all regions of the country have experience with ERT for MPS I, II, and VI, acquired not only through patient treatment but also in clinical trials. Taking the three types of MPS together, over 200 patients have been treated with ERT in our country. This document summarizes the experience of the professionals involved, along with the data available in the international literature, bringing together and harmonizing the information available on the management of these severe and progressive diseases, thus disclosing new prospects for Brazilian patients affected by these conditions

Biochar: pyrogenic carbon for agricultural use: a critical review.

O biocarvão (biomassa carbonizada para uso agrícola) tem sido usado como condicionador do solo em todo o mundo, e essa tecnologia é de especial interesse para o Brasil, uma vez que tanto a ?inspiração?, que veio das Terras Pretas de Índios da Amazônia, como o fato de o Brasil ser o maior produtor mundial de carvão vegetal, com a geração de importante quantidade de resíduos na forma de finos de carvão e diversas biomassas residuais, principalmente da agroindústria, como bagaço de cana, resíduos das indústrias de madeira, papel e celulose, biocombustíveis, lodo de esgoto etc. Na última década, diversos estudos com biocarvão têm sido realizados e atualmente uma vasta literatura e excelentes revisões estão disponíveis. Objetivou-se aqui não fazer uma revisão bibliográfica exaustiva, mas sim uma revisão crítica para apontar alguns destaques na pesquisa sobre biochar. Para isso, foram selecionados alguns temaschave considerados críticos e relevantes e fez-se um ?condensado? da literatura pertinente, mais para orientar as pesquisas e tendências do que um mero olhar para o passad