18,019 research outputs found
Extending the Coordination of Cognitive and Social Perspectives
Cognitive analyses are typically used to study individuals, whereas social analyses are typically used to study groups. In this article, I make a distinction between what one is looking with?one’s theoretical lens?and what one is looking at?e.g., an individual or a group?. By emphasizing the former, I discuss social analyses of individuals and cognitive analyses of groups, additional analyses that can enhance mathematics education research. I give examples of each and raise questions about the appropriateness of such analyses
An approach to the design of mathematical task sequences: Conceptual learning as abstraction
This paper describes an emerging approach to the design of task sequences and the theory that undergirds it. The approach aims at promoting particular mathematical concepts, understood as the result of reflective abstraction. Central to this approach is the identification of available student activities from which students can abstract the intended ideas. The approach differs from approaches in which learning to solve the problem posed is the intended learning. The paper illustrates the approach through data from a teaching experiment on division of fractions
Current-driven magnetization decrease in single crystalline ferromagnetic manganese oxide
The electrical and magnetic response to a bias current has been investigated
in a singlecrystalline ferromagnetic manganese oxide
CaMnO . A significant decrease of the magnetization is
observed at the same threshold current where a non-linearity of V-I
characteristics appears. Such a behavior cannot be understood in the framework
of the filamentary picture usually invoked for the non linearity of the other
manganese oxides. Instead, an analogy with spintronic features might be useful
and experimental signatures seem to be in agreement with excitations of spin
waves by an electric current. This provides an example of a bulk system in
which the spin polarized current induces a macroscopic change in the
magnetization.Comment: 3 pages, 4 figure
Localized exciton-polariton modes in dye-doped nanospheres: a quantum approach
We model a dye-doped polymeric nanosphere as an ensemble of quantum emitters
and use it to investigate the localized exciton-polaritons supported by such a
nanosphere. By determining the time evolution of the density matrix of the
collective system, we explore how an incident laser field may cause transient
optical field enhancement close to the surface of such nanoparticles. Our
results provide further evidence that excitonic materials can be used to good
effect in nanophotonics.Comment: 16 pages, 4 figure
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An external control study of diagram drawing skills for the solution of algebra word problems by novice problem solvers.
Extensión de la coordinación de las perspectivas cognitiva y social
Cognitive analyses are typically used to study individuals, whereas social analyses are typically used to study groups. In this article, I make a distinction between what one is looking with -one’s theoretical lens-and what one is looking at -e.g., an individual or a group-. By emphasizing the former, I discuss social analyses of individuals and cognitive analyses of groups, additional analyses that can enhance mathematics education research. I give examples of each and raise questions about the appropriateness of such analyses.Los análisis cognitivos se usan típicamente para estudiar individuos mientras que los análisis sociales se usan normalmente para estudiar grupos. En este artículo, distingo entre lo que se usa para mirar -el lente teórico propio- y lo que se mira -por ejemplo, un individuo o un grupo-. Enfatizando lo primero, discuto los análisis sociales de individuos y los análisis cognitivos de grupos sociales, análisis adicionales que pueden enriquecer la investigación en educación matemática. Presento ejemplos de cada uno de ellos y planteo preguntas respecto de la conveniencia de estos análisis
Una aproximación al diseño de secuencias de tareas matemáticas: aprendizaje conceptual como abstracción
This paper describes an emerging approach to the design of task sequences and the theory that undergirds it. The approach aims at promoting particular mathematical concepts, understood as the result of reflective abstraction. Central to this approach is the identification of available student activities from which students can abstract the intended ideas. The approach differs from approaches in which learning to solve the problem posed is the intended learning. The paper illustrates the approach through data from a teaching experiment on division of fractions.Este artículo describe una aproximación emergente al diseño de secuencias de tareas y la teoría que la sustenta. La aproximación pretende promover conceptos matemáticos concretos como resultado de una abstracción reflexiva. Es central en esta aproximación la identificación de actividades disponibles para los estudiantes con las que puedan abstraer las ideas pretendidas. La aproximación difiere de aquellas en las que el aprendizaje para resolver problemas es el aprendizaje que se pretende. El artículo ilustra la aproximación a través
de datos de un experimento de enseñanza sobre la división de fracciones.This research was supported by the National Science Foundation (REC0450663 and DRL-1020154). The opinions expressed do not necessarily reflect the views of the foundation
An approach to the design of mathematical task sequences: Conceptual learning as abstraction
This paper describes an emerging approach to the design of task sequences and the theory that undergirds it. The approach aims at promoting particular mathematical concepts, understood as the result of reflective abstraction. Central to this approach is the identification of available student activities from which students can abstract the intended ideas. The approach differs from approaches in which learning to solve the problem posed is the intended learning. The paper illustrates the approach through data from a teaching experiment on division of fractions. Una aproximación al diseño de secuencias de tareas matemáticas: aprendizaje conceptual como abstracción Este artículo describe una aproximación emergente al diseño de secuencias de tareas y la teoría que la sustenta. La aproximación pretende promover conceptos matemáticos concretos como resultado de una abstracción reflexiva. Es central en esta aproximación la identificación de actividades disponibles para los estudiantes con las que puedan abstraer las ideas pretendidas. La aproximación difiere de aquellas en las que el aprendizaje para resolver problemas es el aprendizaje que se pretende. El artículo ilustra la aproximación a través de datos de un experimento de enseñanza sobre la división de fracciones.Handle: http://hdl.handle.net/10481/41628WOS-ESC
Effect of magnetic field and temperature on the ferroelectric loop in MnWO4
The ferroelectric properties of MnWO4 single crystal have been investigated.
Despite a relatively low remanent polarization, we show that the sample is
ferroelectric. The shape of the ferroelectric loop of MnWO4 strongly depends on
magnetic field and temperature. While its dependence does not directly
correlate with the magnetocapacitance effect before the paraelectric
transition, the effect of magnetic field on the ferroelectric polarization loop
supports magnetoelectric coupling.Comment: 3 pages, 4 figures, first report on ferroelectric loop in MnWO
Towards a standardised line list for G191-B2B, and other DA type objects
We present a comprehensive analysis of the far UV spectrum of G191-B2B over
the range of 900-1700{\AA} using co-added data from the FUSE and STIS archives.
While previous identifications made by Holberg et al. (2003) are reaffirmed in
this work, it is found that many previously unidentified lines can now be
attributed to Fe, Ni, and a few lighter metals. Future work includes extending
this detailed analysis to a wider range of DA objects, in the expectation that
a more complete analysis of their atmospheres can be realised.Comment: 4 pages, 2 figures, 1 table: To appear in the proceedings of the
"18th European White Dwarf Workshop" in Krakow, Poland, 201
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