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Teaching mathematics online has been highlighted as one of the solutions to the current crisis for education caused by the COVID-19 virus pandemic and subsequent school closures. However, we do not know what attitudes and experience teachers have towards online teaching. The aim of this study was to gain insights into how Japanese teachers were mentally prepared to tackle online teaching, in particular, when they faced a sudden, unexpected and challenging situation caused by factors beyond their control. Data was gathered from 207 elementary/junior high Japanese teachers using a survey in April 2020. Most participants held relatively positive attitudes towards the use of online teaching of mathematics. Their sense of crisis was very high, and they were anxious about, (a) how to actually make their teaching interactive and (b) how to deal with unexpected technical issues. Their readiness might be explained by their attitudes towards online teaching, the knowledge and time available, and support for making online teaching more interactive for students. We also identified teachers who were ready for such sudden changes and had some ideas to make mathematics lessons interactive with online teaching. [ABSTRACT FROM AUTHOR]

A new fabrication method and its monomer for a polymer-sustained-alignment liquid-crystal (PSA-LC) cell was proposed in this study. The proposed process for formation of a polymer layer is a method to expose visible light for polymerisation of the monomers. As the visible light, a LED-backlight of a LC display (LCD) was used through the intermediary of a polariser. Therefore, the polymer layer was formed by the exposure of the LED-backlight after construction of the LCD. The proposed monomer is 4,4ʹ-dimethacryloyl-oxy-benzil, which can generate a radical by a hydrogen abstraction reaction for an initiation of the polymerisation under exposure of the visible light. The fabricated PSA-LC cell with the proposed method showed high voltage holding ratio, low residual direct current voltage, and comparably small difference in pretilt angle before and after application of an alternate current voltage. Therefore, we can expect that the PSA-LCD would be fabricated without the exposure process of the UV light. Moreover, the PSA-LCD fabricated by the proposed method would be a small level of image sticking. [ABSTRACT FROM AUTHOR]

As a model of polymer-sustained-alignment liquid crystal display (PSA-LCD), the LC cells having the polymer layers produced from mixed monomers of 4,4ʹ-dimethacryloyl-oxy-biphenyl (4,4ʹ-DMABiph) and 4,4ʹ-dimethacryloyl-oxy-benzophenone (4,4ʹ-DMABenz) were fabricated and investigated image-sticking phenomenon with evaluations of residual direct current voltage (VrDC) and difference in pretilt angle before and after application of alternate current voltage (∆tilt). A rate constant of the polymerisation became large with an addition of a small amount of 4,4ʹ-DMABenz into 4,4ʹ-DMABiph. The VrDC was effectively improved with the addition of a small amount of 4,4ʹ-DMABenz because the concentrations of radical and ion in the LC layer were decreased due to enlargement for the rate constant of the polymerisation. The Δtilt was small enough only below 14% of 4,4ʹ-DMABenz in the mixed monomers of 4,4ʹ-DMABiph and 4,4ʹ-DMABenz. We confirmed that the PSA-LC cell produced from the mixed monomers of 4,4ʹ-DMABiph and 4,4ʹ-DMABenz with the weight ratio of 4,4ʹ-DMABenz between 9% and 14% was useful for obtaining the small level of image sticking. [ABSTRACT FROM AUTHOR]

As a model of polymer-sustained-alignment liquid crystal display (PSA-LCD), the LC cells having the polymer layers produced from mixed monomers of 4,4ʹ-dimethacryloyl-oxy-biphenyl (4,4ʹ-DMABiph) and 4,4ʹ-dimethacryloyl-oxy-benzilketal (4,4ʹ-DMABzk) were fabricated and investigated image sticking phenomenon with evaluations of residual direct current voltage (VrDC) and difference in pretilt angle before and after application of alternate current voltage (∆tilt). A rate constant of the polymerisation became remarkably large with an addition of a small amount of 4,4ʹ-DMABzk into 4,4ʹ-DMABiph. The VrDC was effectively improved with the addition of a small amount of 4,4ʹ-DMABzk because the concentrations of radicals and/or ions in the LC layer were decreased due to enlargement for the rate constant of the polymerisation. The Δtilt was small enough only below 10% of 4,4ʹ-DMABzk in the mixed monomers of 4,4ʹ-DMABiph and 4,4ʹ-DMABzk. We confirmed that the PSA-LC cell produced from the mixed monomers of 4,4ʹ-DMABiph and 4,4ʹ-DMABzk with the weight ratio of 4,4ʹ-DMABzk between 6% and 10% was useful for obtaining the small level of image sticking. [ABSTRACT FROM AUTHOR]

A comparative study on the light-induced absorption was performed for lithium niobate and lithium tantalate crystals in which the antisite defects were eliminated by MgO doping. The induced absorption was measured in a spectral window ranging from visible to near infrared with a time resolution of 10 ns. Upon pulsed-light irradiation, a broad absorption peaking near 1250 nm was induced in MgO-doped lithium niobate. It was attributed to the small free polaron, an electron trapped at the regular Nb ion site. In contrast, such absorption in the near infrared originating from the free polaron was absent in MgO-doped lithium tantalates. The findings are highly relevant to the frequency conversion performances of high-power and pulsed lasers based on the current periodically-poled devices. The results also suggest guidelines for improving the crystal qualities. [ABSTRACT FROM AUTHOR]

We propose the method for formation of the vertical alignment polymer film by polymerisation of the monomers being dissolved in the liquid crystal (LC) material. For obtaining the vertical alignment, combination of the two monomers, 4-(4ʹ-octyloxy-biphenyl-4-yloxy)-butyl ester (AOBBE) and 2,7-dimethacryloyl-oxy-phenanthrene (DMAPhen), was found to be useful. The monomer DMAPhen initiates the polymerisation under UV light exposure, and the AOBBE unit induces the vertical alignment without generating any alignment defects. The monomer DMAPhen is useful for maintaining the high voltage holding ratio and low residual direct current voltage after UV light exposure because the molecules of DMAPhen do not remain in the LC layer. [ABSTRACT FROM AUTHOR]

We propose the technique for formation of the polymer orientation film (POF) by polymerisation of the monomers being dissolved in the liquid crystal (LC) material for controlling the orientation of the LC molecules. For obtaining the homeotropic orientation, combination of the two monomers, 4-(4ʹ-octyloxy-biphenyl-4-yloxy)-butyl ester (AOBBE) and 2,7-dimethacryloyl-oxy-anthracene (DMAAnth), was found to be useful. The monomer DMAAnth initiates the polymerisation under ultraviolet (UV) light exposure, and the AOBBE unit induces the homeotropic orientation. The monomer DMAAnth is useful for maintaining the high voltage holding ratio and low residual direct-current voltage after UV light exposure because the molecules of DMAAnth do not remain in the LC layer. [ABSTRACT FROM AUTHOR]