Flow Visualization of Downhill Ski Racers Using Computational Fluid Dynamics

AbstractIn downhill alpine skiing, racers often exceed speeds of 120km/h, with air resistance substantially affecting the overall race times. To date, studies on air resistance in alpine skiing have used wind tunnels and actual skiers to examine the relationship between the gliding posture and magnitude of drag, as well as for the design of skiing equipment. However, these studies have not revealed the flow velocity distribution and vortex structure around the skier. In the present study, we used computational fluid dynamics with the lattice Boltzmann method to derive the relationship between flow velocity in the full tuck position (the downhill racer's speed) and total drag. Furthermore, we visualized the flow around the downhill racer and examined its vortex structure. The results show that the total drag force in the downhill racer model is 27.0N at a flow velocity of 15 m/s, increasing to 185.8N at 40 m/s. Moreover, the visualization of the flow field indicates that the primary drag locations at a flow velocity of 40 m/s are the head, upper arms, lower legs, and thighs (including the buttocks)

A Reading Model from the Perspective of Japanese Orthography: Connectionist Approach to the Hypothesis of Granularity and Transparency

This study presents a computer simulation model of reading in Japanese syllabic Kana and morphographic Kanji. The model was based on the simulation model developed by Harm and Seidenberg (1999) for reading in English. The purpose of building the current model was to verify the validity of the Hypothesis of Granularity and Transparency (HGT) postulated by Wydell and Butterworth (1999), focusing on the granularity dimension. The HGT was developed in order to explain the behavioral dissociation between excellent reading skills in Japanese and poor reading skills in English of an English-Japanese bilingual individual as well as the relatively low incidence of developmental dyslexia in Japan. The current model was successful in simulating the granularity dimension of the HGT. The study also identified several limitations, which need to be addressed in future research.This work was supported by the JSPS-Kakenhi, Grant No. 19530672, where Mutsuo Ijuin was the PI, while Taeko N. Wydell was one of the CIs

A novel echocardiographic-based classification for the prediction of peri-device leakage following left atrial appendage occluder implantation

(1) Background: The assessment of residual peri-device leakages (PDL) after left atrial appendage occlusion (LAAO) remains crucial for post-procedural management. Our study aimed to verify a novel echocardiographic classification for the prediction of PDL. (2) Methods: Echocardiographic data of 72 patients who underwent percutaneous LAAO were evaluated. All echo images were analyzed by two independent investigators using standard analysis software (Image-Arena IA-4.6.4.44 by TomTec ® , Munich, Germany). A total number of 127 studies was evaluated. Forty-four patients had baseline studies, at 45 days and at 6 months post-implantation. We propose a morphological classification of LAA devices based on the amount of echodensity inside the devices into three types: type A showing complete homogenous thrombosis, type B incompletely thrombosed device with inhomogeneous echo-free space 50% of device in various planes, which we called the “ice-cream cone” sign. Each type was matched to the degree of PDL and clinical outcome parameters. (3) Results: Patients with type C had the highest percentage of PDL at 45 days follow-up (type A: 24%, type B: 31%, type C 100% PDL, p < 0.001) and at 6 months follow-up (type A: 7%, type B: 33%, type C 100% PDL, p < 0.001). Notably, device size in patients with PDL was larger than that in patients without PDL at 6 months follow-up (25.6 ± 3.5 mm vs. 28.7 ± 3.4 mm, p = 0.004). Device size in patients with type C appearance was the largest of the three types (type A: 25.9 ± 3.6 mm, type B: 25.8 ± 3.4 mm, type C 29.8 ± 3.0 mm, type A vs. C; p = 0.019; type B vs. C, p = 0.007). (4) Conclusions: In conclusion, PDL are common post-LAAO, and their frequency is underestimated and under-recognized. PDL are much more common in patients with larger LAA ostial sizes and likely lower longitudinal compression. Type C appearance of the LAAO devices (“ice-cream cone sign”) has a high positive predictive value for PDL. Further studies are needed for better delineation of the clinical importance of this proposed classification

[Article] Women in Ancient Political Space

政治空間という概念は幅広いが、本稿では、国家意志の決定・執行及び、国家意志が形成される「場」を政治空間と定義し、そのなかでも朝儀に焦点をしぼって国家意志形成過程への女性の参画を考察したい。 八世紀に女性が朝儀に参列したことは既に指摘されてきた。それは、男女ともの王権への仕奉を前提にした、朝儀への参会が仕奉の一形態だという観念に起因する。 天平宝字四年の藤原仲麻呂の太政大臣任官儀は、仲麻呂を政権の中枢に据えるという王権の構想を、諸司を領導する官人たちに周知するために行われた。女性もここに行立したのは、天皇の意志を官人に周知徹底し国家意志を形成していく過程に組み込まれていたからである。これまでの研究では内侍司が重視されてきたが、王権は、国家意志達成のために他の後宮十二司の女官の動員も必要としたことが、『続日本紀』和銅元年七月乙巳条から明らかとなった。 朝儀への列立にあたっては、五位というラインが重要だった。女性への五位直叙の背景には、朝儀に行立し得る資格を彼女たちに与える王権側の動機があったのである。 『日本書紀』『古事記』にみえる鏡作氏の上祖イシコリトメは、専門職集団を率いる女性リーダーである。七世紀から八世紀にかけて、専門的な職掌で王権へ仕奉した人々の祖先伝承には、部を率いる女性の姿を想定させるものが含まれる。応神紀の吉備氏伝承中の兄媛は、織部を管掌することで王権に仕えた、伴造というべき女性として読み解かれるべきだろう。『日本書紀』に菟狭国造の祖としての菟狭津媛が記され、『古事記』に荒河刀弁という「木国造」がみえる。八世紀には五人の女性国造任命が確認できるが、その背景には、令制以前の女性国造の存在と記憶があったのではないだろうか。 八世紀の女性の朝儀参列は、律令制下で制度化されたのではなく、令制前に遡り得ると判断できる。In this paper, I focus on the decision and execution of national will and the participation of women in the ancient political space. I would like to point out women participation in the process of forming national will, by research the ceremonies in court of the monarch held to form national will. Researcher has already pointed out that women attended the Imperial Ceremonies in the 8th century. It stems from the idea that both men and women should contribute the kingship. The ruler thought attendance at ceremonies was also he and her obligation to the state. In 760, monarch Koken held an appointment ceremony to inform leading senior officials of the idea of putting Fujiwara no Nakamaro at the top of the administration, and female officials also attended the ceremony. Female officials also attended the ceremony because it was incorporated into the process of thoroughly pursuing the will of the monarch and forming the national will. In the past, researchers have emphasized Naishi-shi. But the kingship also required the cooperation of female officials of Twelve offices to achieve the purpose of the nation. It became clear from the record of “Shoku Nihongi” on July 15, 708. It should not be overlooked that the higher rank of fifth was important in participating in the 8th century Imperial Council. When women were promoted fifth rank, researchers have considered a special benefit for being a woman. However, the existence of a fifth-ranked female official should be considered as a motive of the kingship giving qualify them for attending the Imperial Council. Going back in time, the ancestral folklore of those who served the kingship in professional positions from the 7th to the 8th centuries includes those reminiscent of the woman who leads the department. For example, Kagami-tsukuri's ancestor Ishikoritome, who appears in “Nihon Shoki” and “Kojiki,” is a female leader who leads a professional group. E-hime, a powerful tribe in the Kibi region during the time of Ōjin, was a woman who ruled Oribe and served the monarch, and she should be called the official who managed the ancient professional group. “Nihon Shoki” and “Kojiki” describe women of the local tribes who belonged to the kingship and were appointed as the local chieftain. Usatsuhime is described as the ancestor of Usa no Kuni-no-Miyatsuko (Kokuzō) in “Nihon Shoki”, and Arakawatobe was called “Ki-no-Kuni-no-Miyatsuko” in “Kojiki”. The monarch of the 8th century appointed six women to be Kokuzō. Behind this may have been the existence and memory of women's Kokuzō before ritsuryō polity. In the 8th century, women attended at the ceremonies in court of the monarch. That was not first created by the Ritsuryō system but had executed before Ritsuryō system.departmental bulletin pape