151 research outputs found
TEM analysis and comparison on the BDC using several reanalysis data sets
第3回極域科学シンポジウム 横断セッション「中層大気・熱圏」 11月26日(月) 国立極地研究所 2階大会議
成層圏大循環の構造と長期変動
学位の種別: 課程博士審査委員会委員 : (主査)東京大学教授 高橋 正明, 東京大学教授 木本 昌秀, 東京大学教授 佐藤 正樹, 東京大学教授 佐藤 薫, 東京大学准教授 東塚 知己University of Tokyo(東京大学
Fractal mechanism of basin of attraction in passive dynamic walking
Passive dynamic walking is a model that walks down a shallow slope without any control or input. This model has been widely used to investigate how humans walk with low energy consumption and provides design principles for energy-efficient biped robots. However, the basin of attraction is very small and thin and has a fractal-like complicated shape, which makes producing stable walking difficult. In our previous study, we used the simplest walking model and investigated the fractal-like basin of attraction based on dynamical systems theory by focusing on the hybrid dynamics of the model composed of the continuous dynamics with saddle hyperbolicity and the discontinuous dynamics caused by the impact upon foot contact. We clarified that the fractal-like basin of attraction is generated through iterative stretching and bending deformations of the domain of the Poincaré map by sequential inverse images. However, whether the fractal-like basin of attraction is actually fractal, i.e., whether infinitely many self-similar patterns are embedded in the basin of attraction, is dependent on the slope angle, and the mechanism remains unclear. In the present study, we improved our previous analysis in order to clarify this mechanism. In particular, we newly focused on the range of the Poincaré map and specified the regions that are stretched and bent by the sequential inverse images of the Poincaré map. Through the analysis of the specified regions, we clarified the conditions and mechanism required for the basin of attraction to be fractal
CAPTDURE: Captioned Sound Dataset of Single Sources
In conventional studies on environmental sound separation and synthesis using
captions, datasets consisting of multiple-source sounds with their captions
were used for model training. However, when we collect the captions for
multiple-source sound, it is not easy to collect detailed captions for each
sound source, such as the number of sound occurrences and timbre. Therefore, it
is difficult to extract only the single-source target sound by the
model-training method using a conventional captioned sound dataset. In this
work, we constructed a dataset with captions for a single-source sound named
CAPTDURE, which can be used in various tasks such as environmental sound
separation and synthesis. Our dataset consists of 1,044 sounds and 4,902
captions. We evaluated the performance of environmental sound extraction using
our dataset. The experimental results show that the captions for single-source
sounds are effective in extracting only the single-source target sound from the
mixture sound.Comment: Accepted to INTERSPEECH202
Major Depressive Disorder Complicated with Spinocerebellar Ataxia: Report of 2 Cases
Background: It is known that patients with spinocerebellar ataxia (SCA) tend to exhibit depressive symptoms. But the pathology of depressive symptoms complicated with SCA, including the reaction to the stress resulting from decreased motor function and central dysfunction due to neurodegeneration, is controversial and remains to be elucidated. To our knowledge, there have been hardly any reports on treatment methods of major depressive disorder (MDD) complicated with SCA. Case Reports: We report 2 cases in which selective serotonin reuptake inhibitors (SSRIs) were effective against MDD complicated with SCA. Interestingly, one of the patients developed the symptoms of spinocerebellar degeneration (SCD) during the course of the MDD, and the other patient developed the symptoms of MDD during the course of SCA, but complete remission of the MDD occurred in both cases. In our cases, the depressive symptoms may have been caused mainly by an abnormality of reversible neural transmission including serotonin transmission due to central dysfunction, and there is the unlikely possibility that the depressive symptoms are reactive to the stress due to decreased motor function, because the depressive symptoms decreased with SSRIs. Conclusion: Although cerebellar degeneration is irreversible in SCA patients, our cases suggest that MDD complicated with SCA may be reversible and treatable using antidepressants such as SSRIs with few adverse events. Therefore, it is important for neurologists to detect MDD complicated with SCA early and consult a psychiatrist in order to improve quality of life of SCA patients
Proactive Received Power Prediction Using Machine Learning and Depth Images for mmWave Networks
This study demonstrates the feasibility of the proactive received power
prediction by leveraging spatiotemporal visual sensing information toward the
reliable millimeter-wave (mmWave) networks. Since the received power on a
mmWave link can attenuate aperiodically due to a human blockage, the long-term
series of the future received power cannot be predicted by analyzing the
received signals before the blockage occurs. We propose a novel mechanism that
predicts a time series of the received power from the next moment to even
several hundred milliseconds ahead. The key idea is to leverage the camera
imagery and machine learning (ML). The time-sequential images can involve the
spatial geometry and the mobility of obstacles representing the mmWave signal
propagation. ML is used to build the prediction model from the dataset of
sequential images labeled with the received power in several hundred
milliseconds ahead of when each image is obtained. The simulation and
experimental evaluations using IEEE 802.11ad devices and a depth camera show
that the proposed mechanism employing convolutional LSTM predicted a time
series of the received power in up to 500 ms ahead at an inference time of less
than 3 ms with a root-mean-square error of 3.5 dB
Maneuverable and Efficient Locomotion of a Myriapod Robot with Variable Body-Axis Flexibility via Instability and Bifurcation
Aoi Shinya, Yabuuchi Yuki, Morozumi Daiki, et al. Maneuverable and Efficient Locomotion of a Myriapod Robot with Variable Body-Axis Flexibility via Instability and Bifurcation. Soft Robotics 6, NT64 (2023); https://doi.org/10.1089/soro.2022.0177
Sudden change in fractality of basin boundary in passive dynamic walking
The 11th International Symposium on Adaptive Motion of Animals and Machines. Kobe University, Japan. 2023-06-06/09. Adaptive Motion of Animals and Machines Organizing Committee.Poster Session P7
IL-6 negatively regulates osteoblast differentiation through the SHP2/MEK2 and SHP2/Akt2 pathways in vitro
It has been suggested that interleukin-6 (IL-6) plays a key role in the pathogenesis of rheumatoid arthritis (RA), including osteoporosis not only in inflamed joints but also in the whole body. However, previous in vitro studies regarding the effects of IL-6 on osteoblast differentiation are inconsistent. The aim of this study was to examine the effects and signal transduction of IL-6 on osteoblast differentiation in MC3T3-E1 cells and primary murine calvarial osteoblasts. IL-6 and its soluble receptor significantly reduced alkaline phosphatase (ALP) activity, the expression of osteoblastic genes (Runx2, osterix, and osteocalcin), and mineralization in a dose-dependent manner, which indicates negative effects of IL-6 on osteoblast differentiation. Signal transduction studies demonstrated that IL-6 activated not only two major signaling pathways, SHP2/MEK/ERK and JAK/STAT3, but also the SHP2/PI3K/Akt2 signaling pathway. The negative effect of IL-6 on osteoblast differentiation was restored by inhibition of MEK as well as PI3K, while it was enhanced by inhibition of STAT3. Knockdown of MEK2 and Akt2 transfected with siRNA enhanced ALP activity and gene expression of Runx2. These results indicate that IL-6 negatively regulates osteoblast differentiation through SHP2/MEK2/ERK and SHP2/PI3K/Akt2 pathways, while affecting it positively through JAK/STAT3. Inhibition of MEK2 and Akt2 signaling in osteoblasts might be of potential use in the treatment of osteoporosis in RA. © 2013 The Japanese Society for Bone and Mineral Research and Springer.This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: https://doi.org/10.1007/s00774-013-0514-1Kaneshiro S., Ebina K., Shi K., et al. IL-6 negatively regulates osteoblast differentiation through the SHP2/MEK2 and SHP2/Akt2 pathways in vitro. Journal of Bone and Mineral Metabolism 32, 378 (2014); https://doi.org/10.1007/s00774-013-0514-1
X-ray magnetic circular dichroism and photoemission study of the diluted ferromagnetic semiconductor ZnCrTe
We have performed x-ray magnetic circular dichroism (XMCD) and valence-band
photoemission studies of the diluted ferromagnetic semiconductor
ZnCrTe. XMCD signals due to ferromagnetism were observed at the Cr
2p absorption edge. Comparison with atomic multiplet calculations suggests that
the magnetically active component of the Cr ion was divalent under the
tetrahedral crystal field with tetragonal distortion along the crystalline a-,
b-, and c-axes. In the valence-band spectra, spectral weight near the Fermi
level was strongly suppressed, suggesting the importance of Jahn-Teller effect
and the strong Coulomb interaction between the Cr 3d electrons
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