ESTUDO DAS TRÊS DIMENSÕES DO PROBLEMA DIDÁTICO DE NÚMEROS RACIONAIS NA FORMA FRACIONÁRIA

Neste artigo de cunho teórico, tecemos reflexões a respeito das três dimensões (epistemológica, econômica e ecológica) do problema didático de números racionais na forma fracionária, em razão da importância do ensino dessa unidade de conhecimentos matemáticos desde as séries iniciais do Ensino Fundamental. Para a realização deste estudo, tomamos como referências a Teoria Antropológica do Didático para evidenciar a razão de ser de número fracionário que leve o professor a construir um novo saber-fazer a partir da mobilização das Organizações Matemáticas resultantes do estudo das três dimensões do problema didático do referido objeto matemático. O estudo da dimensão epistemológica permitiu construir um Modelo Epistemológico de Referência – MER- composto por três modelos secundários: M1 – associado à concepção de medida, M2 – associado à concepção de quociente e M3 – associado à concepção de razão. Esses modelos orientam o desenvolvimento de conhecimentos a respeito de medida, de distribuição e de comparação que são oriundos de situações que mobilizam, prioritariamente, essas concepções e que, para serem resolvidas implicam diretamente na mobilização da concepção parte-todo e, talvez, da concepção de operador. Quanto à dimensão econômica, observamos que as habilidades definidas pela BNCC para a apropriação de racionais na forma fracionária, embora evoquem situações que propusemos em nosso MER, não percebemos o foco em situações significativas que conduziriam o aluno a entender a necessidade desse novo campo numérico. No que diz respeito à dimensão ecológica, a BNCC parece evidenciar um dos nichos de números racionais que participam da sobrevivência da proporcionalidade, por exemplo. Mas, algumas das restrições que podem dificultar e/ou impedir a justificação de tarefas sobre números fracionários são os desafios que os professores devem enfrentar no design de tipo de tarefas (e de tarefas) que permitam aos alunos alcançar as competências e habilidades relacionadas com a unidade temática “Números”, em especial com o objeto de conhecimento “números fracionários”. No final deste estudo, propusemos um Modelo Praxeológico Matemático de Referência desenhado a partir de nosso MER, em que sugerimos o trabalho com os três modelos secundários, apoiando-se na construção de organizações didáticas que considerem as organizações matemáticas desses modelos

A mechanistic perspective on pex1 and pex6, two aaa+ proteins of the peroxisomal protein import machinery

In contrast to many protein translocases that use ATP or GTP hydrolysis as the driving force to transport proteins across biological membranes, the peroxisomal matrix protein import machinery relies on a regulated self-assembly mechanism for this purpose and uses ATP hydrolysis only to reset its components. The ATP-dependent protein complex in charge of resetting this machinery—the Receptor Export Module (REM)—comprises two members of the “ATPases Associated with diverse cellular Activities” (AAA+) family, PEX1 and PEX6, and a membrane protein that anchors the ATPases to the organelle membrane. In recent years, a large amount of data on the structure/function of the REM complex has become available. Here, we discuss the main findings and their mechanistic implications.This work was financed by FEDER—Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2020—Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020, and by Portuguese funds through FCT—Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior in the framework of the project PTDC/BEX-BCM/2311/2014 (POCI-01-0145-FEDER-016613) and the project “Institute for Research and Innovation in Health Sciences” (POCI-01-0145-FEDER-007274). This work is a result of the project NORTE-01-0145-FEDER-000008—Porto Neurosciences and Neurologic Disease Research Initiative at I3S, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). A.B.-B., A.G.P., M.J.F., T.F. and T.A.R. are supported by Fundação para a Ciência e Tecnologia, Programa Operacional Potencial Humano do QREN, and Fundo Social Europeu

Lag times in the publication of network meta-analyses: A survey

Objective We assessed the extent of lag times in the publication and indexing of network meta-analyses (NMAs). Study design This was a survey of published NMAs on drug interventions. Setting NMAs indexed in PubMed (searches updated in May 2020). Primary and secondary outcome measures Lag times were measured as the time between the last systematic search and the article submission, acceptance, online publication, indexing and Medical Subject Headings (MeSH) allocation dates. Time-to-event analyses were performed considering independent variables (geographical origin, Journal Impact Factor, Scopus CiteScore, open access status) (SPSS V.24, R/RStudio). Results We included 1245 NMAs. The median time from last search to article submission was 6.8 months (204 days (IQR 95-381)), and to publication was 11.6 months. Only 5% of authors updated their search after first submission. There is a very slightly decreasing historical trend of acceptance (rho=-0.087; p=0.010), online publication (rho=-0.080; p=0.008) and indexing (rho=-0.080; p=0.007) lag times. Journal Impact Factor influenced the MeSH allocation process, but not the other lag times. The comparison between open access versus subscription journals confirmed meaningless differences in acceptance, online publication and indexing lag times. Conclusion Efforts by authors to update their search before submission are needed to reduce evidence production time. Peer reviewers and editors should ensure authors' compliance with NMA standards. The accuracy of these findings depends on the accuracy of the metadata used; as we evaluated only NMA on drug interventions, results may not be generalisable to all types of studies

Proposta e análise de uma organização didática para o ensino de conceitos geométricos via provas e demonstração

Resumo: Este artigo é um recorte de uma pesquisa maior que analisa uma proposta didática, cujas tarefas articulam provas e demonstrações, como alternativa metodológica para minimizar as dificuldades relacionadas ao tópico ‘quadriláteros’, em um curso de licenciatura em Matemática. Essas tarefas envolvem construções geométricas em um ambiente de papel e lápis, em que os alunos são solicitados a construir figuras geométricas e justificar matematicamente as técnicas utilizadas. Em uma parte das tarefas propostas, solicitava-se cumpri-las por meio de um raciocínio hipotético-dedutivo. Neste texto, apresentamos uma análise a priori de algumas das tarefas que não puderam ser experimentadas, mas que faziam parte do rol de situações propostas na investigação supracitada. A análise vislumbrada apoia-se, principalmente, na Teoria Antropológica do Didático (TAD) e na concepção de prova e demonstração. Nas análises que propusemos, além da TAD, as fases exploratórias das diferentes tarefas e a articulação entre os registros de representação (tratamento e conversão) nos permitiram mostrar que não basta o aluno se basear apenas na apreensão perceptiva para fazer uma validação formal das afirmações tecidas nas diferentes tarefas. É necessário que se explore, principalmente as apreensões operatórias e discursivas da figura para vislumbrar caminhos que permitem a construção de provas intelectuais.Palavras-chave: Prova; Demonstração; Geometria; Quadriláteros; Análise a priori. Proposal and analysis of a didactic organization for the geometric concepts teaching by tests and demonstrationAbstract: This article is a clipping of a larger survey that analyzes a didactic proposal whose tasks articulate proof and demonstrations as a methodological alternative to minimizing the difficulties related to the topic ' quadrilaterals ' in a bachelor's degree course in mathematics. These tasks involve geometric constructs, in a paper and pencil environment, in which students are asked to construct geometric figures and to justify mathematically the techniques used. In a part of the proposed tasks, it was requested to fulfil them by a hypothetical-deductive reasoning. In this text, we presented a priori analysis of some of the tasks that could not be experienced, but which were part of the list of situations proposed in the aforementioned investigation. The envisaged analysis is primarily supported by the anthropological theory of the didactic (ATD) and the conception of proof and demonstration. In the analysis we have proposed, beyond the ATD, the exploratory phases of the different tasks, the articulation between semiotic register representation (treatment and conversion) allowed us to show that it is not enough that student only supports the perceptual apprehension to make formal validation of the affirmations woven in the different tasks. It is necessary to explore, mainly, the operative seizures and discursive of the figure to glimpse paths that allow the construction of intellectual evidence.Keywords: Proof; Demonstration; Geometry; Quadrilaterals; A priori analysis.

Atividades de estudo e investigação para a construção de modelos de pirâmides tringulares

Neste artigo, os autores têm como objetivo fazer uma reflexão a respeito da razão de ser do ensino de planificação de superfícies de sólidos geométricos, para construção de modelos, partindo de um estudo matemático já realizado a fim de propor Atividades de Estudo e Investigação – AEI, no sentido de Chevallard. Este estudo, prioritariamente de cunho teórico, foca no significado que alunos do ensino básico poderão construir, especificamente, na construção do modelo para uma pirâmide triangular a partir da planificação de sua superfície. Para o desenvolvimento dessa reflexão, utilizamos o software Geogebra como ferramenta para a construção do modelo, por permitir a manipulação da construção geométrica realizada e levantar conjecturas e, ainda, a produção de modelos de diversos tipos. Por outro lado, possibilita ao professor ampliar discussões a respeito de planificações, tanto para outros conteúdos, como é o caso da medida de volumes, quanto para outros tipos de sólidos

Um modelo epistemológico de referência para o estudo da planificação de superfícies de pirâmides triangulares

Retomamos neste artigo um anteriormente publicado no sentido de ampliar as discussões lá propostas analisando a situação a partir de outro referencial. Trata-se da apresentação de um Modelo Epistemológico de Referência (MER) para a construção, no Geogebra, de planificações de superfícies de pirâmides triangulares de altura determinada, verificando condições e restrições para a referida construção. Tal MER pode justificar organizações didáticas que promovam Atividades de Estudo e Pesquisa (PEP) desenvolvidas a partir de questionamentos realizados durante a atividade que conduzirão a resolução do problema proposto. Um dos objetivos do estudo é proporcionar uma razão de ser para o trabalho com a representação plana de sólidos geométricos

As Operações com Números Racionais e seus Significados a partir da Concepção Parte-todo

We present a reflection regarding operations with fractional numbers focusing on the part-all conception through some activities that can contribute to teaching practices at the elementary school level. A brief characterization of the all-part conception is provided along with descriptions of activities involving the four basic operations based on the use of flat figures, although other conceptions may emerge during the solution. We limit our considerations to this conception because it is the most frequent, in textbooks as well as teacher practice, although it is not used to justify operational rules of fractional numbers. Key-words: Fractions. Fractional Numbers. Operations.Neste artigo, apresentamos uma reflexão a respeito das operações com números fracionários focalizando a concepção parte-todo por meio de algumas atividades que possam contribuir para a prática docente na escola básica. O estudo explicita uma breve caracterização da concepção parte-todo e atividades envolvendo as quatro operações fundamentais tratadas em figuras planas, embora outras concepções possam ser mobilizadas durante a solução. Restringimos nossas considerações a essa concepção visto ser a mais freqüente, tanto em livros didáticos, quanto na prática do professor, embora não seja utilizada para justificar as regras operatórias dos números fracionários. Palavras-chave: Frações. Números Fracionários. Operações

Comparison Between Maximum Inspiratory Pressure Measured By A Digital Manometer And By An Electronic Inspiratory Muscle Training Device

Aims: To compare maximum inspiratory pressure (MIP) measured by a digital manometer and by an inspiratory muscle training (IMT) device and to evaluate hemodynamic changes after measurements. Methods: The sample included male and female individuals older than 18 years admitted to an intensive care unit who were hemodynamically stable, not being treated with vasoactive drugs or sedated, intubated or tracheostomized, and who were in the process of being weaned from mechanical ventilation. MIP was measured by both devices on three different occasions, with an occlusion time of 20 seconds and a 5-minute interval between measurements. The following parameters were assessed: respiratory rate, mean arterial pressure, and respiratory rate before and after each measurement by each device. The statistical analysis was made in the Statistical Analysis System and the R Project for Statistical Computing V. 3.1.2 softwares, using the ANOVA and the Wilcoxon tests. Results: Fifty-eight patients were included in the study. The mean value obtained for MIP was -46.22 centimeters of water (cmH(2)O) in the digital manometer and -13.15 cmH(2)O (p<0.001) in the IMT device. Heart rate showed a significant increase (p<0.0001) both before and after all measurements in both devices. Mean arterial pressure showed a statistically significant difference only before and after the first measurement by the digital manometer and before and after the second measurement by the IMT device (p<0.001). The respiratory rate oscillated significantly before and after the three measurements by both devices (p<0.0001). The hemodynamic parameters remained within reference values after MIP measurements. Conclusions: The digital manometer recorded a higher MIP than that measured by the IMT device. The hemodynamic parameter values oscillated in both devices, but they remained within the normal range and were not clinically significant.2

Comparison Between Maximum Inspiratory Pressure Measured By A Digital Manometer And By An Electronic Inspiratory Muscle Training Device

To compare maximum inspiratory pressure (MIP) measured by a digital manometer and by an inspiratory muscle training (IMT) device and to evaluate hemodynamic changes after measurements. Methods: The sample included male and female individuals older than 18 years admitted to an intensive care unit who were hemodynamically stable, not being treated with vasoactive drugs or sedated, intubated or tracheostomized, and who were in the process of being weaned from mechanical ventilation. MIP was measured by both devices on three different occasions, with an occlusion time of 20 seconds and a 5-minute interval between measurements. The following parameters were assessed: respiratory rate, mean arterial pressure, and respiratory rate before and after each measurement by each device. The statistical analysis was made in the Statistical Analysis System and the R Project for Statistical Computing V. 3.1.2 softwares, using the ANOVA and the Wilcoxon tests. Results: Fifty-eight patients were included in the study. The mean value obtained for MIP was -46.22 centimeters of water (cmH(2)O) in the digital manometer and -13.15 cmH(2)O (p<0.001) in the IMT device. Heart rate showed a significant increase (p<0.0001) both before and after all measurements in both devices. Mean arterial pressure showed a statistically significant difference only before and after the first measurement by the digital manometer and before and after the second measurement by the IMT device (p<0.001). The respiratory rate oscillated significantly before and after the three measurements by both devices (p<0.0001). The hemodynamic parameters remained within reference values after MIP measurements. Conclusions: The digital manometer recorded a higher MIP than that measured by the IMT device. The hemodynamic parameter values oscillated in both devices, but they remained within the normal range and were not clinically significant.2

Benefícios dos Ativadores Seletivos dos Recetores de Vitamina D em Doentes Transplantados Renais

Severe chronic kidney disease may lead to disturbances, such as hyperphosphatemia, increased secretion of fibroblast growth factor -23 (FGF -23) and vitamin D deficiency. These may increase plasmatic levels of parathyroid hormone, and decrease plasmatic levels of calcium. Altogether, these may contribute to the development of secondary hyperparathyroidism, and to abnormalities in mineral metabolism. Kidney transplantation is the best option to improve longevity and quality of life in end -stage chronic kidney disease patients. Vitamin D deficiency has been associated with cardiovascular disease, which is the leading cause of death in chronic kidney disease. Therefore, diagnosing this deficiency may be pivotal for minimizing mortality in chronic kidney disease, because pharmacological treatments for this deficiency may be prescribed. Calcitriol is indicated for the treatment of vitamin D deficiency, both in chronic kidney disease and in kidney transplanted patients. However, calcitriol may increase the plasmatic levels of calcium and phosphorous, which can lead to vascular calcifications, that have been associated with cardiovascular mortality. Selective vitamin D receptor activators are indicated for the treatment of vitamin D deficiency in chronic kidney disease. These have the advantage of being associated with lower increases of plasmatic levels of calcium and phosphorous. These drugs also seem to have additional effects that may minimise patient morbidity and mortality, especially due to potentially reducing cardiovascular events. Unfortunately, there are few studies about the use of these drugs in kidney transplanted patients. Here we present a review about the physiology of vitamin D, the consequences of its deficiency in chronic kidney disease and in kidney transplanted patients, and about the diagnosis and treatment of this deficiency. Finally, we discuss the new line of research about the efficacy and safety of selective vitamin D receptor activators in kidney transplanted patients