Conocimiento de matemáticas y la competencia de reconocer el desarrollo del razonamiento up and down en los estudiantes

El objetivo de este estudio es aportar información sobre el papel que desempeña el conocimiento de matemáticas de los estudiantes para maestro (EPM) cuando piensan en el aprendizaje de las matemáticas de los estudiantes de primaria. Nuestro estudio se centra en el razonamiento up and down que es una de las componentes que facilitan el desarrollo del razonamiento proporcional. 92 EPM resolvieron una tarea en la que tenían que interpretar las respuestas de estudiantes de educación primaria a un problema que implicaba el razonamiento up and down. Identificamos tres perfiles de EPM caracterizados por la relación entre el conocimiento de matemáticas y la competencia de reconocer el desarrollo del razonamiento up and down en los estudiantes.

Cómo reconocen los estudiantes para maestro evidencias del razonamiento up and down en los estudiantes

Este estudio examina cómo los estudiantes para maestro identifican evidencias del razonamiento up and down en los estudiantes de primaria. Este razonamiento implica dos procesos: la reconstrucción de la unidad y la representación de fracciones. 92 estudiantes para maestro respondieron una tarea que consistía en analizar tres respuestas de estudiantes de educación primaria a un problema de proporcionalidad que mostraban diferentes características de esta manera de razonar. En este estudio presentamos algunos aspectos del análisis que estamos realizando para categorizar la manera en la que los estudiantes para maestro reconocen evidencias de este razonamiento, y cómo este reconocimiento se relaciona con la manera en la que reconocen los elementos matemáticos relevantes para resolver el problema.

Magnetization reversal of ferromagnetic nanowires studied by magnetic force microscopy

The magnetization reversal of two-dimensional arrays of parallel ferromagnetic Fe nanowires embedded in nanoporous alumina templates has been studied. By combining bulk magnetization measurements (superconducting quantum interference device magnetometry) with field-dependent magnetic force microscopy (MFM), we have been able to decompose the macroscopic hysteresis loop in terms of the irreversible magnetic responses of individual nanowires. The latter are found to behave as monodomain ferromagnetic needles, with hysteresis loops displaced (asymmetric) as a consequence of the strong dipolar interactions between them. The application of field-dependent MFM provides a microscopic method to obtain the hysteresis curve of the array, by simply registering the fraction of up and down magnetized wires as a function of applied field. The observed deviations from the rectangular shape of the macroscopic hysteresis loop of the array can be ascribed to the spatial variation of the dipolar field through the inhomogeneously filled membrane. The system studied proves to be an excellent example of the two-dimensional classical Preisach model, well known from the field of hysteresis modeling and micromagnetism.

Validation of a mobility item bank for older patients in primary care

Background: To develop and validate an item bank to measure mobility in older people in primary care and to analyse differential item functioning (DIF) and differential bundle functioning (DBF) by sex. Methods: A pool of 48 mobility items was administered by interview to 593 older people attending primary health care practices. The pool contained four domains based on the International Classification of Functioning: changing and maintaining body position, carrying, lifting and pushing, walking and going up and down stairs. Results: The Late Life Mobility item bank consisted of 35 items, and measured with a reliability of 0.90 or more across the full spectrum of mobility, except at the higher end of better functioning. No evidence was found of non-uniform DIF but uniform DIF was observed, mainly for items in the changing and maintaining body position and carrying, lifting and pushing domains. The walking domain did not display DBF, but the other three domains did, principally the carrying, lifting and pushing items. Conclusions: During the design and validation of an item bank to measure mobility in older people, we found that strength (carrying, lifting and pushing) items formed a secondary dimension that produced DBF. More research is needed to determine how best to include strength items in a mobility measure, or whether it would be more appropriate to design separate measures for each construct.