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121.
Within research on mathematics teachers and/or their professional development, the concept of identity emerges as a critique of views of how teaching practice is related to teachers’ ‘internal states’ of knowledge and beliefs. Identity relates teachers’ professional lives to teaching practices and to the contexts in which the teaching and/or professional development occurs. However, what might count as the context still needs in-depth discussion. In order to contribute to the development of a theoretical framework for understanding mathematics teachers’ professional lives, we will draw on one remarkable teacher’s identity as a primary mathematics teacher in relation to one political, sociocultural, and pedagogical context. We use this teacher’s experience to discuss how education policies that create what Ball (2003) called ‘terrors of performativity’ tend to impede the formation of a balanced teacher identity. 相似文献
122.
J. MEDINA YU. G. GUREVICH G. N. LOGVINOV P. RODRÍGUEZ G. GONZÁLEZ DE LA CRUZ 《Molecular physics》2013,111(19):3133-3138
The problem of the effective thermal diffusivity of two-layer systems is investigated using the photoacoustic spectroscopy. The experimental results are examined in terms of the effective thermal parameters of the composite system determined from a homogeneous material that produces the same physical response under an external perturbation in the detector device. It is shown that the effective thermal conductivity is not symmetric under exchange of the two layers of the composite, i.e. the effective thermal parameters depend upon which layer is illuminated in the photoacoustic experiments. Particular emphasis is given to the characterization of the interface thermal conductivity between the layer system. 相似文献
123.
Docoslis A Espinoza LA Zhang B Cheng LL Israel BA Alexandridis P Abbott NL 《Langmuir : the ACS journal of surfaces and colloids》2007,23(7):3840-3848
Nonuniform ac (alternating current) electric fields created by microelectrodes are investigated for their influence on the transport of the vesicular stomatitis virus (VSV) from aqueous suspensions of physiological ionic strength to surfaces on which the VSV is captured. Whereas passive diffusion did not lead to detectable levels of virus captured on a surface when using titers of VSV as high as 107 PFU/mL, nonuniform electric field-mediated transport led to the detection of 105 PFU/mL of virus in 2 min. An order-of-magnitude analysis of the time scales associated with virus transport to the microelectrodes inside media of physiological relevance indicates that electrothermal fluid flow (and the resulting viscous drag forces on the virus) rather than dielectrophoresis likely constitutes the major mechanism for virus transport far from the electrodes. The influence of dielectrophoresis was calculated to be confined to a region within a few micrometers of the electrodes and to lead to collection patterns of both virus and fluorescently labeled particles near the electrodes that were found to be in qualitative agreement with experiments. These observations and conclusions are discussed within a theoretical framework presented in the paper. The results presented in this work, when combined, suggest that ac electrokinetic phenomena can be used to expeditiously transport and capture viruses onto surfaces from solutions of high ionic strength, thus providing a potentially useful approach to addressing a bottleneck in the development of devices that allow for rapid sampling and detection of infectious biological agents. 相似文献
124.
Luis Espinoza Felipe Bulat Danahe Coll Francisco Coll Marcelo D. Preite Manuel Cortés 《合成通讯》2013,43(11):1963-1974
The chemical synthesis, starting from deoxycholic acid methyl ester, of several brassinosteroids analogues with different oxygenated functions in ring C, is described. Three of them showed growth-promoting activity 相似文献
125.
Thomet FA Pinyol P Villena J Espinoza LJ Reveco PG 《Natural product communications》2010,5(10):1587-1590
Two new boldine derivatives: the 3-thiocarbamateboldine (3) and the 2,9-O,O-diacetyl-3-thiocarbamateboldine (4) have been synthesized and their cytotoxicity evaluated. 相似文献
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M. Araya D.E. Díaz-Droguett M. Ribeiro K. F. Albertin J. Avila V.M. Fuenzalida R. Espinoza D. Criado 《Journal of Non》2012,358(5):880-884
In this work we report studies of the photoluminescence emission in samples based on Si/SiOx films deposited by the Pulsed Electron Beam Ablation (PEBA) technique. The samples were prepared at room temperature using targets with different Si/SiO2 concentrations. The samples were characterized using X-ray Absorption Edge Spectroscopy (XANES) at the Si―K edge, Raman spectroscopy, Photoluminescence (PL) and X-ray Photoelectron Spectroscopy (XPS). The concentration of a-Si and nc-Si in the film was dependent on the silicon concentration in the target. It was also observed that the PL is strongly dependent on the structural amorphous/crystalline arrangement. 相似文献
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