340 research outputs found
sj-pdf-1-jcb-10.1177_0271678X211045449 - Supplemental material for MRS-measured glutamate versus GABA reflects excitatory versus inhibitory neural activities in awake mice
No full textSupplemental material, sj-pdf-1-jcb-10.1177_0271678X211045449 for MRS-measured glutamate versus GABA reflects excitatory versus inhibitory neural activities in awake mice by Yuhei Takado, Hiroyuki Takuwa, Kazuaki Sampei, Takuya Urushihata, Manami Takahashi, Masafumi Shimojo, Shoko Uchida, Nobuhiro Nitta, Sayaka Shibata, Keisuke Nagashima, Yoshihiro Ochi, Maiko Ono, Jun Maeda, Yutaka Tomita, Naruhiko Sahara, Jamie Near, Ichio Aoki, Kazuhisa Shibata and Makoto Higuchi in Journal of Cerebral Blood Flow & Metabolism</p
Dynamic Stress and Flow Analysis of Extraterrestrial Regolith for Planetary Exploration Rovers
No full textIn recent decades, robotic mobile systems known as rovers have been used for lunar/planetary exploration missions. These missions aim to elucidate the origin of planets
and life and investigate potential resources including ice water. In the past missions, rovers
have played a significant role in lunar/planetary exploration missions, and found many scientific discoveries such as the presence of water on Mars. These findings indicate that rovers
are of great importance for lunar/planetary explorations.
Despite the great successes so far accomplished in these missions, rovers experienced
mobility problems on lunar/planetary surfaces, covered with fine granular soil, popularly
known as regolith. In particular, excessive slippage and sinkage of the wheel make rovers
difficult to follow their desired route. In addition, these problems induce being stuck in
deformable terrains and mission failures. In future missions, it is expected that the difficulty
level in the exploration mission increases, for example, it would be required the explorations
in difficult environments - near and inside the lunar craters - and the efficient explorations
by high-speed rovers. The increase in difficulty increases the risk of mobility problems.
Avoiding such situations contributes to improving exploration efficiency and minimizing
mission failures.
To address the mobility issues, it is necessary to predict the wheel-traveling performance in advance, and for that purpose, it is effective to understand and model the wheel-soil
interactions. In many studies, classical terramechanics models for large vehicles have commonly been used to predict wheel performance for lunar/planetary rovers. Lunar/planetary
rovers generally have small wheels equipped with grousers, which are like a plate, to improve their tractive performance. The grouser wheel shows more complicated wheel-soil
interaction mechanics than the non-grouser wheel. The classical models do not consider the
grouser wheel and soil deformation and dynamics caused by the wheel, being not suitable to
predict wheel performance for lunar/planetary rovers. To improve the model predictions for
the rovers, it is necessary to understand the interaction between the grouser wheel and soft
terrain.
There are mainly two approaches to analyzing wheel-soil interactions. One is the analysis of the wheel performance such as drawbar pull and stress distributions at the contactpatch of the wheel. Another is the analysis of the soil behavior such as the soil flow fields. In
our laboratory, past studies have focused on the drawbar pull and stress distributions of the
wheel. In addition to these studies, it is very beneficial to analyze soil flow and deformation
and integrate them with the result of wheel performance for discussions.
This study, therefore, addresses mainly the following three issues: 1) experimental analysis of the soil flow fields beneath the grouser wheel based on an imaging technique, 2) development of a particle-based simulation to analyze soil flow and stress fields and evaluation
of its validity, 3) evaluation of the soil flow and stress fields using the developed simulation,
assuming the lunar environments - lunar soil and gravity -.
Chapter 1 introduces past and ongoing lunar/planetary exploration rovers with their
exploration environments as a research background. In addition, the motivation and objective
of this work are presented with the state of the art on wheel-soil interactions.
Chapter 2 experimentally performs the single-wheel tests on the two types of soils to
analyze soil flow fields beneath the grouser wheel: Toyoura standard sand and the lunar
regolith simulant. This study employs a computer vision-based technique known as particle
image velocimetry (PIV) for the soil flow analysis. The main objective of this chapter is to
reveal the difference in the soil flow between Toyoura standard sand and the lunar regolith
simulant. The experimental results are discussed from the viewpoints of soil flow velocity,
flow region, entry and exit angles of the wheel, slip ratio, and force and torque acting on the
wheel. The results indicate that the soil flow characteristics considerably differ depending
on the soil properties, being lower fluidity with an increase in the soil shear strength. In
addition, it is also presented that the lower fluidity of the soil contributes to improving the
wheel performance.
Chapter 3 develops a particle-based simulation technique known as the discrete element
method (DEM) for the single-wheel simulations for the analysis of thw soil flow and stress
fields beneath the grouser wheel. In the DEM, the particle motion is determined based on the
contact model. This study implements a rolling resistance and cohesive models to reproduce
the behavior of the lunar regolith simulant. As the particle parameters in the model are of
great importance in the DEM to reproduce the soil behavior, the parameters are tuned for
Toyoura standard sand and the lunar regolith simulant based on the parametric study. The
DEM is validated by comparing with the experimental data at the following four perspectives: slip ratio, ruts formed after the wheel pass, entry and exit angles, and soil flow velocity
fields. The validation results show that the DEM can reproduce the soil flow/deformation
and wheel performance on the two different types of soils under any slip conditions.
Chapter 4 evaluates the soil behavior and wheel performance by using the developed
DEM simulation. As this dissertation focuses on lunar exploration rovers, the effect of the
lunar regolith simulant and lunar gravity on the soil behavior is investigated by performing
single-wheel simulations. The result of the simulations is discussed based on the wheel
sinkage, drawbar pull, soil flow fields, and dynamic stress in the soil. The result shows thatthe cohesive soil contributes to improving the wheel performance due to its higher shear
strength, and the lower gravity adversely affects the wheel performance. In addition, for
future efficient explorations, the effect of increasing speeds on the wheel-soil interactions is
also described in this chapter. The simulation results for the high-speed locomotion show that
the soil flow and dynamic stress increase as the wheel speed increases. The wheel sinkage,
which is an indicator to evaluate the wheel performance, depends on the shear strength of
the soil. This result indicates that the effect of increasing speeds on the wheel performance
depends on the shear strength of the soils.
Chapter 5 summarizes the results of this study. In conclusion, this work achieved the
following outcomes to understand wheel-soil interactions for lunar/planetary rovers: 1) visualization of soil flow beneath the grouser wheel, 2) development of the simulation to analyze
soil behavior, 3) evaluation of the soil flow and dynamic stress fields. These contributions
would be beneficial to reconsidering the classical terramechanics models for lunar/planetary
rovers. As a final remark of this dissertation, the directions for future studies are also presented in this chapter
Evaluation of Planetary Rover Wheel Performance on Sloped Loose Soil Based on Discrete Element Method (離散要素法を用いた惑星探査ローバー車輪の軟弱斜面走 行性能の評価)
No full textExplorations of celestial bodies have been conducted by wheel type robots known as
rovers, in recent decades. These planetary surfaces like the Moon or Mars, are covered by
fine grain soil, and it is difficult for rovers to explore such environments since rovers slip and
get stuck. In fact, NASA/JPL’s Mars Exploration Rover, known as Spirit which landed on
Mars in 2004, was buried in loose Martian soil in 2009. In addition, future missions need to
account for challenging terrains to explore interesting sites such as lava tubes. Thus, it is an
essential task for lunar/planetary rovers to improve their traveling performance. Therefore,
the objectives of this thesis are to investigate the influence of the grouser wheel parameters
on the wheel performance and to design the appropriate wheel for future exploration rovers.
Researchers have studied the wheel performance based on both simulation and experiment so far. In particular, numerical simulations are widely used in the field, thanks to the
improved computational hardware in recent years. As one of the commonly used numerical
methods in wheel-soil contact simulation that include soil deformation, there is the Discrete
Element Method (DEM). The DEM is a particle-scale numerical method and can handle the
discontinuity model. The advantages of this method are capturing many features of the soil
dynamics behavior and being able to consider the soil deformation. On the other hand, for
this research work, the studies cover the performance of wheel with grousers under fine particle environments. The observation and simulation of wheel-soil interaction are key elements
in this research. Hence, DEM is applied for this study to observe the wheel-soil interaction
on particle levels. As a result of this research, the developed DEM simulation model is first
validated through a series of experiments, including angle of repose tests and single wheel
tests. Furthermore, the parametric wheel simulation is studied by changing several key wheel
parameters through a reiterative process for designing a wheel. As a result, the relationship
between the soil behavior and the wheel performance is understood through this research.
Finally, the appropriate wheel is proposed by combining less slippage and less sinkage based
on the parametric simulations. This proposed wheel can indeed reduce the wheel slippage
and sinkage on loose soil.
These results show that rovers with proposed wheels could be able to explore on finegrain soil more easily and travel more challenging environments like sloped terrain required
for future exploration missions. Moreover, the outcomes have a potential to develop better
wheel for Mars exploration rovers
Two Types of Landlords Drawn in Elizabeth Gaskell's "The Doom of the Griffiths" (Special Issue Dedicated to Professor NAKAMURA, Shoko)
No full textThe short story, “The Doom of the Griffiths” was written by Elizabeth Gaskell in 1857, more than one year after her former fictional creation, “The Poor Clare”. The story presents a conflict between two types of landlords ; a landlord who may prosper and one who may not. This is the author's first treatment of an issue that becomes a major theme in her later works. “The Doom of the Griffiths” is a tale about the fall of the Griffiths family, people of the landlord class. At the beginning of the story is an explanation of why the Griffiths were doomed to fall. When Owen Glendower, a Welsh hero in the Middle Ages, rebelled against Henry IV, an ancestor of the Griffiths named Rhys ap Gryfydd betrayed Owen, who believed in him. It means that Rhys ap Gryfydd was shrewd, and that he tried to side with those most likely to be victorious. In great anger, Owen, who was said to be able to use magic, cursed the traitor and his descendants. As a result, members of the Griffiths family were doomed by Owen to fail and disappear after nine generations. Owen prophesied that at that time a son should slay his father, the ninth Griffiths. After this brief explanation the main plot begins. Two generations are described ; the ninth named Robert Griffiths and his son, Owen Griffiths. They are father and son, but are quite different in manners. Robert is the second son and inherits the estate of the Griffiths as a result of his elder brother's death. He is gifted and able to create his own future. On the other hand, Owen is the only son who is an heir to the estate from the moment of his birth. He has no choice but to succeed his father. Therefore, he is passive and does not try to take a step forward, even though he becomes under the necessity of earning a living. Their attitudes toward marriage also differ. The father gets married to a rich attorney’s daughter after he inherited his family's estate. And after his first wife, who is Owen's mother, died, he marrys again a beautiful young widow with a little boy named Robert, who, coincidentally, has his stepfather's name. The son, on the other hand, secretly gets married to the beautiful daughter of a man who works as a half farmer and half fisherman. The girl's name is Nest. They have a baby named Owen. Because the young couple cannot make a living, the wife and their baby live with her father in his cottage. Owen frequently and surreptitiously comes to the house from his father's manor house. The wife's father, who is a tenant of the Griffiths estate, endures this irregular situation, believing that his daughter will be Lady Griffiths in the future. Robert's new wife schemes to drive Owen out of the mansion and make her child Robert inherit the family's estate. As a result of her scheming, her husband becomes estranged from his son and begins to favor his stepson. One day she tries to irreparably break the relationship between Robert and his biological son to make sure of her biological son’s inheritance, and she exposes Owen's secret marriage to her husband, lying and insinuating that Nest is a prostitute. The angry father goes to his son’s secret home to require him to separate from his wife, and snatches the little Owen from Owen's arms to throw the baby back at Nest. As a result, the baby falls to the floor and dies. At last, Owen decides to leave his father's mansion for ever to live with his wife in a big city, earning his bread. It is, however, too late. After some troubles, the father moves into action. He and his son are placed in a situation in which they struggle on the edge of a precipice. A push of the son to escape from the father's grip causes the father to fall off the cliff, to hit his head against the edge of a boat, and to die. Though it seems that this is a fulfillment of the prophecy, the author denies the supernatural element, emphasizing that the father's death is accidental. As a squire, Robert, a person who is shrewd and selfish like his ancestor Rhys ap Gryfydd, prospers, but he is also very cruel, while Owen, a passive liberal, is disqualified as a landlord. Through the story, the author is critical of the father. The last of the story deals with Owen, his wife, and her father, who should leave the country before the dead body of the squire is found. They venture out on a stormy sea to disappear into the night. The author partly suggests that the three are shipwrecked and die. She, however, leaves room for another interpretation. The three might safely arrive in Liverpool, where Owen could “gain a livelihood by his own exertions.” The author accepts Owen's way of living when he leaves the status of a landlord. That is the reason that Owen is the younger of the two central characters. It is important that the name of the second son Roger in Wives and Daughters, who is Robert's successor, has the initial “R”, and that of the elder son Osborne in the same novel, who is Owen's successor, has also the initial “O”. It means that “The Doom of the Griffiths” developed into Wives and Daughters.9KJ00002373446論文Articledepartmental bulletin pape
The audio database of Hatoma lexicon (Southern Ryukyuan)
No full textThis is a database of words and expressions of Hatoma language (Yaeyaman, Southern Ryukyuan). Almost all lexical entries have corresponding audio files, spoken and recorded by the first author.
Follow the readme file in NINJAL repository
R&D Management Practices and Innovation: Evidence from a Firm Survey
No full textThis Open Access book provides a detailed account of firms’ research and development (R&D) management practices, and whether and how R&D management practices are associated with the success and the nature (explorative or exploitive) of innovation, using a unique survey of firms in Japan. While there is wide agreement that innovation is a key determinant for growth of firms, there are few studies that systematically and quantitatively investigate what firms do in their R&D management to create innovation. Utilizing insights from theoretical and empirical studies on innovation, the authors focus on the following four aspects of R&D management: the organizational structure of R&D, staged project management for R&D projects, compensation and incentive schemes for R&D personnel, and a firm’s risk preferences and corporate culture. The authors examine whether and how R&D management practices are linked to the likelihood of firms’ success in making product innovations and the choice between explorative and exploitive innovation. The book furnishes vital information that can be used as a reference for future theoretical and empirical analyses of R&D management practices and innovation. This monograph is highly recommended to academics and practitioners who seek an in-depth and detailed analysis of R&D management. This is an open access book
R&D Management Practices and Innovation: Evidence from a Firm Survey
No full textThis Open Access book provides a detailed account of firms’ research and development (R&D) management practices, and whether and how R&D management practices are associated with the success and the nature (explorative or exploitive) of innovation, using a unique survey of firms in Japan. While there is wide agreement that innovation is a key determinant for growth of firms, there are few studies that systematically and quantitatively investigate what firms do in their R&D management to create innovation. Utilizing insights from theoretical and empirical studies on innovation, the authors focus on the following four aspects of R&D management: the organizational structure of R&D, staged project management for R&D projects, compensation and incentive schemes for R&D personnel, and a firm’s risk preferences and corporate culture. The authors examine whether and how R&D management practices are linked to the likelihood of firms’ success in making product innovations and the choice between explorative and exploitive innovation. The book furnishes vital information that can be used as a reference for future theoretical and empirical analyses of R&D management practices and innovation. This monograph is highly recommended to academics and practitioners who seek an in-depth and detailed analysis of R&D management. This is an open access book
Impact of omission/reduction of vincristine from R-CHOP in treatment of DLBCL
No full text博士(医学) 乙第3118号(主論文の要旨、要約、審査結果の要旨、本文)，著者名:Shoko MARSHALL, Noriko NISHIMURA, Norihito INOUE, Hirofumi YAMAUCHI, Naoko TSUYAMA, Kengo TAKEUCHI, Yuko MISHIMA, Masahiro YOKOYAMA, Toshie OGASAWARA, Naoki MORI, Tetsuya OGAWA, Hiroshi SAKURA, Yasuhito TERUI，タイトル:Impact of Omission/Reduction of Vincristine From R-CHOP in Treatment of DLBCL，掲載誌:Clinical lymphoma, myeloma & leukemia(2152-2669)，巻・頁・年:21巻3号 p.162～169(2021)，著作権関連情報© 2020 The Author(s).，DOI:10.1016/j.clml.2020.12.01
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