Fractions are well known to be difficult to learn. Various hypotheses have been proposed in order to explain those difficulties: fractions can denote different concepts; their understanding requires a conceptual reorganization with regard to natural numbers; and using fractions involves the articulation of conceptual knowledge with complex manipulation of procedures. In order to encompass the major aspects of knowledge about fractions, we propose to distinguish between conceptual and procedural knowledge. We designed a test aimed at assessing the main components of fraction knowledge. The test was carried out by fourth-, fifth- and sixth-graders from the French Community of Belgium. The results showed large differences between categories. Pupils seemed to master the part-whole concept, whereas numbers and operations posed problems. Moreover, pupils seemed to apply procedures they do not fully understand. Our results offer further directions to explain why fractions are amongst the most difficult mathematical topics in primary education. This study offers a number of recommendations on how to teach fractions.
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http://dx.doi.org/10.3389/fpsyg.2013.00715 | DOI Listing |
Haematologica
March 2025
Experimental Hematology, Vall d'Hebron Institute of Oncology (VHIO), Vall d'Hebron Barcelona Hospital Campus, Barcelona, Spain; Department of Medicine, Universitat Autònoma de Barcelona, Bellaterra.
Continuous treatment with ibrutinib not only exerts tumor control but also enhances T cell function in patients with chronic lymphocytic leukemia (CLL). We conducted longitudinal multi-omics analyses in samples from CLL patients receiving ibrutinib upfront to identify potential adaptive mechanisms to Bruton tyrosine kinase (BTK) inhibition during the first 12 months of continuous therapy. We found that ibrutinib induced a decrease in the expression of exhaustion markers and the proportion of Tregs and Tfh cells normalized to levels observed in healthy donors.
View Article and Find Full Text PDFFront Toxicol
February 2025
Department of Surgical Sciences, Division of Functional Pharmacology and Neuroscience, Uppsala University, Uppsala, Sweden.
Background: The specific and non-specific toxicities of cryoprotective agents (CPAs) for semen or spermatozoa cryopreservation/vitrification (SC/SV) remain challenges to the success of assisted reproductive technologies.
Objective: We searched for and integrated the physicochemical and toxicological characteristics of small-molecule CPAs as well as curated the information of all extenders reported for carnivores to provide a foundation for new research avenues and computational cryobiology.
Methods: The PubMed database was systematically searched for CPAs reported in SC/SV of carnivores from 1964 to 2024.
Drugs Context
March 2025
Cardiology Department, Arrhythmia Unit, University Hospital La Paz, Madrid, Spain.
Background: This analysis assesses the effectiveness and tolerability profile of vericiguat in patients with heart failure with reduced ejection fraction (HFrEF) and implantable cardioverter-defibrillator, with an emphasis on the emergence of ventricular arrhythmias.
Methods: Retrospective analysis of patients with HFrEF and implantable cardioverter-defibrillator who started treatment with vericiguat in daily clinical practice in a tertiary university hospital in Spain.
Results: The study population comprised 14 patients treated since January 2023.
R Soc Open Sci
March 2025
1Institute of Radiochemistry, China Institute of Atomic Energy, Beijing 102413, People's Republic of China.
A foamed sodium carboxymethyl cellulose (CMC) material was prepared under nitric acid conditions. Unlike traditional CMC materials, this foaming method is straightforward and does not require additional foaming agents. Owing to its high stability and load capacity, the foam can realize long-term quantitative storage and load a variety of metal ions; therefore, it has broad application prospects in the field of loaded materials for metal ions.
View Article and Find Full Text PDFFront Cell Infect Microbiol
March 2025
Department of Pharmacy, Qilu Hospital (Qingdao), Cheeloo College of Medicine, Shandong University, Qingdao, Shandong, China.
Objective: This study aimed to predict and evaluate the efficacy of various polymyxin B dosing regimens for Gram-negative bacteremia using Monte Carlo simulation, with a specific focus on assessing the efficacy in patients receiving continuous renal replacement therapy (CRRT). The goal was to optimize clinical dosing regimens and guide rational polymyxin B use in practice.
Methods: A total of 1,939 Gram-negative bacterial strains were analyzed, collected between April 2019 and December 2021 through the China Bloodstream Gram-negative Pathogens Antimicrobial Resistance and Virulence Surveillance Network (CARVIS-NET).
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