The inverse relation between the size and the number of parts

This study analyses children’s understanding of the inverse relationship between size and number of parts when fractions and division situations are involved. A survey by questionnaire was conducted with 42 Portuguese fourth-graders trying to address two questions: 1) How do children understand the inverse relation between size and number of parts in partitive and quotitive division situations? And 2) How do children understand the inverse relation when fractions are involved in part-whole and quotient interpretations? Results suggest that these distinct situations have different impacts on children’s understanding of the inverse relations between the size and the number of parts.CIEC – Research Centre on Child Studies, IE, UMinho (FCT R&D unit 317), PortugalNational Funds through the FCT (Foundation for Science and Technology) and co-financed by European Regional Development Funds (FEDER) through the Competitiveness and Internationalization Operational Program (POCI) with the reference POCI-01-0145-FEDER-007562info:eu-repo/semantics/publishedVersio

A compreensão das relações numéricas na aprendizagem das frações: um estudo comparativo com crianças brasileiras e portuguesas

The understanding of rational numbers is one of the major conceptual challenges faced by students in mathematics learning in basic education. Regarding fractions, to establish the inverse relationship between the numerator and the denominator becomes a key issue in concept formation. The main goals of this study were: to understand if the inverse relationship between smaller quantities than the unit in quotient and part-whole situations influences the learning of fractions; and to compare Brazilian and Portuguese students’ comprehension of the inverse relationship between quantities in fraction problems, using quotient and part-whole situations. The results indicate that students have a better grasp of the inverse relationship between the quantities in the quotient situation and also showed that Portuguese students performed significantly better than Brazilian students in the both types of situations. The discrepancy in student performance can be explained by differences in the curricula of mathematics in grade four in these countries. Implications for the teaching of mathematics in these two countries were also discussed.A compreensão dos números racionais é um dos maiores desafios conceituais enfrentados pelos estudantes na aprendizagem matemática durante a educação básica. No que diz respeito às frações, estabelecer a relação inversa entre o numerador e o denominador torna-se uma habilidade fundamental na construção do conceito. Os objetivos deste estudo foram: verificar como a compreensão da relação inversa entre quantidades menores do que a unidade, apresentadas nas situações de quociente e parte-todo, influencia na aprendizagem das frações; e perceber se existe diferença no desempenho entre alunos brasileiros e portugueses quanto à compreensão da relação inversa entre quantidades em problemas de fração. Os resultados indicam que os estudantes apresentam uma melhor compreensão da relação inversa entre quantidades na situação quociente e apontam que os desempenhos dos estudantes portugueses são significativamente melhores do que os dos estudantes brasileiros, nos diferentes tipos de situação. A discrepância no desempenho dos estudantes pode ser explicada pelas diferenças nos programas curriculares de matemática no quarto ano nesses países. Implicações no ensino da matemática nesses dois países foram discutidas.CIEC – Research Centre on Child Studies, IE, UMinho (FCT R&D unit 317), PortugalNational Funds through the FCT (Foundation for Science and Technology) and co-financed by European Regional Development Funds (FEDER) through the Competitiveness and Internationalization Operational Program (POCI) with the reference POCI-01-0145-FEDER-007562info:eu-repo/semantics/publishedVersio

Portuguese and Brazilian children understanding the inverse relation between quantities: the case of fractions

This study compares Portuguese and Brazilian fourth-graders (n=84) understanding of the inverse relation between quantities when fractions are presented in quotient and part-whole interpretations. It addresses three questions: 1) How do children understand this inverse relation in quotient interpretations of fractions? 2) How do children understand this inverse relation in part-whole interpretation of fractions? 3) Are there differences in performance between Brazilian and Portuguese children concerning these issues? A survey by questionnaire was applied and 16 part-whole and quotient problems were analyzed. Results indicate that quotient interpretation promotes more the understanding of this inverse relation; Portuguese and Brazilian children perform differently when solving the fraction problems.CIEC - Centro de Investigação em Estudos da Criança, IE, UMinho (UI 317 da FCT), PortugalFundos Nacionais através da FCT (Fundação para a Ciência e a Tecnologia) e cofinanciado pelo Fundo Europeu de Desenvolvimento Regional (FEDER) através do COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) com a referência POCI-01-0145-FEDER-007562info:eu-repo/semantics/publishedVersio

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Reactive oxygen species generation in peripheral blood monocytes and oxidized LDL are increased in hyperlipidemic patients

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Objectives: Experimental and in vitro evidences have established that reactive oxygen species (ROS) generated by vascular wall cells play a key role in atherogenesis. Here, we evaluated the rate of ROS generation by testing peripheral monocytes in naive hyperlipidemic subjects. Design and methods: Primary hypercholesterolemic, combined hyperlipidemic, and normopilidemic individuals were studied. ROS generation and the mitochondrial electrical transmembrane potential were estimated by flow cytometry. Plasma oxidized (ox) LDL levels and lipid profile were measured by ELISA and enzymatic colorimetric methods. Results: Both hyperlipidemic groups presented significantly higher rates of monocyte ROS generation and elevated plasma levels of ox-LDL. Combined hyperlipidemic subjects presented increased levels of small dense LDL and insulin. Significant positive correlations between monocyte ROS generation and ox-LDL concentrations were found in pooled data. Conclusions: These data provide evidence that ROS production by circulating monocytes from hyperlipidemic subjects may contribute to the systemic oxidative stress and possibly to atherogenesis. (C) 2009 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.421212221227Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundo de Apoio ao EnsinoPesquisa e A ExtensAo (FAEPEX/FCM/UNICAMP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq