1,499 research outputs found

    Two teacher educatorsā€™ approaches to developing preservice elementary teachersā€™ mathematics assessment literacy: Intentions, outcomes, and new learning

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    The purpose of this study was to examine and reflect on two teacher educatorsā€™ approaches to developing preservice elementary teachersā€™ mathematics assessment literacy. We explored the similarities and differences in preservice teachersā€™ conceptions of good assessment practices and their critique of assessment items. We found that we, as course instructors, had different assumptions pertaining to the role of preservice teachers in the development of assessment and offered different assessment-related course activities. Despite these differences, there were more similarities than differences between the two groups of the preservice teachers with regard to their overall perceptions about good assessment practices and their critique of assessment items. However, we also observed differences in the criteria they used in critiquing assessment items. Discussions and implications are presented in accordance with these findings as a means to improve our own teaching and student learning

    Revisiting Multiplication Area Models for Whole Numbers

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    We argue that there are two conceptually different area models for whole number multiplication: area-to-area model and lengths-to-area model depending on how multiplication operation is conceived: action on / change of an initial quantity, or operation / coordination of two quantities. These models complement each other to promote studentsā€™ conceptual understanding of whole number multiplication and help students extend their understanding of whole number multiplication to fraction multiplication

    Revisiting Multiplication Area Models for Whole Numbers

    Get PDF
    We argue that there are two conceptually different area models for whole number multiplication: area-to-area model and lengths-to-area model depending on how multiplication operation is conceived: action on / change of an initial quantity, or operation / coordination of two quantities. These models complement each other to promote studentsā€™ conceptual understanding of whole number multiplication and help students extend their understanding of whole number multiplication to fraction multiplication

    Very short-term forecasting of precipitation based on hybrid surface rainfall technique in Korea

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    PĆ³ster presentado en: 3rd European Nowcasting Conference, celebrada en la sede central de AEMET en Madrid del 24 al 26 de abril de 2019

    Comprehensive understanding of cathodic and anodic polarization effects on stability of nanoscale oxygen electrode for reversible solid oxide cells

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    Whereas solid oxide cells (SOCs), which perform dual functions of power generation (fuel-cell mode) and energy storage (electrolysis mode) with high efficiency at high temperatures, are considered a potent candidate for future energy management systems, it is yet far from their practical use due to the fact that the stable long-term operations have not been achieved. Particularly, degradations of oxygen-electrode in the both electrolysis and fuel-cell operations are considered as the most imminent issues that should be overcome. Unfortunately, even the origins and mechanisms of degradation in the oxygen-electrode have not been clearly established due to the difficulties in precise assessments of microstructural/compositional changes of porous electrode, which is a typical form in actual solid oxide cells, and due to the diversities in operating conditions, electrode structure and material, fabrication history, and so on. We simultaneously investigated the degradation phenomena in electrolysis and fuel-cell operations for 540h using identical two half cells composed of a geometrically well-defined, nanoscale La0.6Sr0.4Co0.2Fe0.8O3-Ī“ (LSCF) dense film with a thickness of ~ 70 nm on Ce0.9Gd0.1O2-Ī“ electrolyte. Owing to the benefit of well-defined geometry of LSCF thin film, the microstructural/compositional changes in LSCF films were successfully analyzed in nanoscale, and the correlation between the components of electrochemical impedance and the major origins resulting in degradations was clarified. Furthermore, we suggest the most probable degradation mechanisms, and importantly, it is newly suggested that kinetic demixing/decomposition of LSCF, which is not readily observable in the typical porous-structured electrode, are highly probable to affect the both fuel-cell and electrolysis long-term degradations

    Ninjurin1 positively regulates osteoclast development by enhancing the survival of prefusion osteoclasts

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    Osteoclasts (OCs) are bone-resorbing cells that originate from hematopoietic stem cells and develop through the fusion of mononuclear myeloid precursors. Dysregulation of OC development causes bone disorders such as osteopetrosis, osteoporosis, and rheumatoid arthritis. Although the molecular mechanisms underlying osteoclastogenesis have been well established, the means by which OCs maintain their survival during OC development remain unknown. We found that Ninjurin1 (Ninj1) expression is dynamically regulated during osteoclastogenesis and that Ninj1(-/-) mice exhibit increased trabecular bone volume owing to impaired OC development. Ninj1 deficiency did not alter OC differentiation, transmigration, fusion, or actin ring formation but increased Caspase-9-dependent intrinsic apoptosis in prefusion OCs (preOCs). Overexpression of Ninj1 enhanced the survival of mouse macrophage/preOC RAW264.7 cells in osteoclastogenic culture, suggesting that Ninj1 is important for the survival of preOCs. Finally, analysis of publicly available microarray data sets revealed a potent correlation between high NINJ1 expression and destructive bone disorders in humans. Our data indicate that Ninj1 plays an important role in bone homeostasis by enhancing the survival of preOCs

    Compromised ventilation caused by tracheoesophageal fistula and gastrointestinal endoscope undergoing removal of disk battery on esophagus in pediatric patient -A case report-

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    Ingestion of disk batteries may have serious complications such as esophageal burn, perforation, and tracheoesophageal fistula, particularly when the battery is caught in the esophagus. Proper placement of the tracheal tube is critical when tracheoesophageal fistula was occurred from esophageal impaction the battery. Endoscopy of upper gastrointestinal tract in infants and children is an important and effective tool for the diagnosis and treatment of foreign body ingestion. But upper gastrointestinal endoscopy in infant and children has very high risk of tracheal compression and airway compromise. We present a case of ventilatory compromise during insertion of the upper gastrointestinal endoscopy in 16-month-old child with tracheoesophageal fistula secondary to disk battery ingestion
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