66 research outputs found
Geodesics of multivariate normal distributions and a Toda lattice type Lax pair
No full textWe study geodesics of multivariate normal distributions with respect to the Fisher metric. First it will be shown that a computational formula for geodesics can be understood using the block Cholesky decomposition and a natural Riemannian submersion. Next a mid point algorithm for geodesics will be obtained. And finally a new Toda lattice type Lax pair will be derived from the geodesic and the block Cholesky decomposition
Minimal cylinders in the three-dimensional Heisenberg group
No full textWe study minimal cylinders in the three-dimensional Heisenberg group Nil3 using the generalized Weierstrass type representation, the so-called loop group method. We characterize all non-vertical minimal cylinders in terms of pairs of two closed plane curves which have the same signed area. Moreover, as a byproduct of the construction, spacelike CMC cylinders in the three-dimensional Minkowski space can also be obtained
The impact of computer science education in primary schools: Evidence from a randomized controlled trial in Iraq.
No full textWith the growing digitization of society, there is a need to enhance computational thinking as an indispensable skill for modern daily life. Consequently, computer science education for children at early ages has become increasingly important. This study conducts a randomized controlled trial to examine the impact of the interventions using educational robotics as well as computer-aided mathematics drills (via a "math app") on students' performance in primary schools in Basra, Iraq. We provide several new empirical findings. First, the short-run impact of robotics-based learning on computational thinking is positive and statistically significant for girls, particularly poor performing girls, but not for boys. Second, the impact on computational thinking is augmented by introducing a math app, further improving computational thinking. Together, these two interventions also enhance general intelligence. Third, the positive impact was still evident more than three months after the interventions for girls who received both computer science and math education, suggesting their complementarity. Our results show that computer science education using educational robots in primary schools is effective in enhancing computational thinking and relevant skills
School ICT resources, teachers, and online education : Evidence from school closures in Japan during the COVID-19 pandemic
No full textSchool ICT resources, teachers, and online education: Evidence from school closures in Japan during the COVID-19 pandemic
No full textAs schools worldwide were forced to close due to the COVID-19 pandemic in early 2020, they struggled to switch to online education. Using Japan's nationwide administrative data, we examine the impact of schools' ICT equipment and teachers' IT skills on the provision of online classes, communication with students' families, and teachers' working hours during and shortly after the closures. To isolate supply-side effects, we exploit differences in ICT resources between public elementary and junior high schools using a municipality-level fixed effects model, the level at which ICT resources are decided. We find that basic ICT equipment was critical to implementing online classes, but IT skills were not. Furthermore, we observe no effect of ICT resources on schools' communication with families. However, IT skills were associated with teachers' working hours. In particular, weak IT skills resulted in a higher percentage of teachers working overtime
School ICT resources, teachers, and online education : Evidence from school closures in Japan during the COVID-19 pandemic
No full textAs schools worldwide were forced to close due to the COVID-19 pandemic in early 2020, they struggled to switch to online education. Using Japan’s nationwide administrative data, we examine the impact of schools’ ICT equipment and teachers’ IT skills on the provision of online classes, communication with students’ families, and teachers’ working hours during and shortly after the closures. To isolate supply-side effects, we exploit differences in ICT resources between public elementary and junior high schools using a municipality-level fixed effects model, the level at which ICT resources are decided. We find that basic ICT equipment was critical to implementing online classes, but IT skills were not. Furthermore, we observe no effect of ICT resources on schools’ communication with families. However, IT skills were associated with teachers’ working hours. In particular, weak IT skills resulted in a higher percentage of teachers working overtime
The impact of computer science education in primary schools: Evidence from a randomized controlled trial in Iraq
No full textRepresentation formula for discrete indefinite affine spheres
No full textWe present a representation formula for discrete indefinite affine spheres via loop group factorizations. This formula is derived from the Birkhoff decomposition of loop groups associated with discrete indefinite affine spheres. In particular we show that a discrete indefinite improper affine sphere can be constructed from two discrete plane curves. (C) 2020 Elsevier B.V. All rights reserved
Maximal surfaces in the Lorentzian Heisenberg group
No full textThe 3-dimensional Heisenberg group can be equipped with three different types of left-invariant Lorentzian metric, according to whether the center of the Lie algebra is spacelike, timelike or null. Using the second of these types, we study spacelike surfaces of mean curvature zero. These surfaces with singularities are associated with harmonic maps into the 2-sphere. We show that the generic singularities are cuspidal edge, swallowtail and cuspidal cross-cap. We also give the loop group construction for these surfaces, and the criteria on the loop group potentials for the different generic singularities. Lastly, we solve the Cauchy problem for harmonic maps into the 2-sphere using loop groups, and use this to give a geometric characterisation of the singularities. We use these results to prove that a regular spacelike maximal disc with null boundary must have at least two cuspidal cross-cap singularities on the boundary
Orikuchi Shinobu's "Korean" Representation: I Feel Like Wanting to be a Korean
No full textThe purpose of this paper is to consider the possibility and problems of “Korean” representation of Shinobu Orikuchi (1887-1953), who was a poet and a folklorist. The method to do so is to verify the representation of “Korean” in his poem “Sunakeburi” (1924). This poem is based on the experiences of the author during the Great Kanto Earthquake and depicts Koreans massacred by Japanese. In this poem he said, “I feel like wanting to be a Korean.”
This poem which expresses things that cannot be expressed by traditional methods of Tanka was later classified as a non-Tanka by the author. The name non-Tanka means continuity and discontinuity with Tanka. He describes Koreans as being discriminated against and feared by others as continuity with Tanka, and expresses the fear of the Japanese who kill Koreans by discontinuity. As a result, he preserved discrimination against Koreans in poetry, but he was able to face the criminal acts of the Japanese. The euphemistic expression that “I feel like wanting to be a Korean,” is because he realized that he was a part of the crime. He could not speak out and say “I would like to be a Korean.”
His representation of Koreans had the problem of preserving discrimination, but there was the possibility of scooping up the victim’s voice without forgetting his position as a perpetrator
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