The main aim of this study is to examine chemical similarities and differences among metal-poor stars belonging to these old Galactic components as a clue to determine their early chemodynamical ...evolution. In this paper, a similar analysis is performed to determine abundances of an additional 17 elements. We show that, in metallicities below Fe/H ~ -2, the abundance ratios of many elements in the thick disk, inner halo, and outer halo subsamples are largely similar. In particular, our results favor the scenario that the inner and outer halo components formed through an assembly of multiple progenitor systems that experienced various degrees of chemical enrichments, while the thick disk formed through rapid star formation with an efficient mixing of chemical elements. The lower Na/Fe and Zn/Fe observed in stars with the outer halo kinematics may further suggest that progenitors with longer star formation timescales contributed to the buildup of the relatively metal-rich part of stellar halos.
ABSTRACT We present Subaru/Faint Object Camera and Spectrograph and Keck/Deep Imaging Multi-Object Spectrometer medium-resolution spectroscopy of a tidally disrupting Milky Way (MW) globular cluster ...Palomar 5 (Pal 5) and its tidal stream. The observed fields are located to cover an angular extent of ∼17° along the stream, providing an opportunity to investigate a trend in line-of-sight velocities (Vlos) along the stream, which is essential to constrain its orbit and underlying gravitational potential of the MW's dark matter halo. A spectral fitting technique is applied to the observed spectra to obtain stellar parameters and metallicities (Fe/H) of the target stars. The 19 stars most likely belonging to the central Pal 5 cluster have a mean Vlos of −58.1 0.7 km s−1 and metallicity Fe/H = −1.35 0.06 dex, both of which are in good agreement with those derived in previous high-resolution spectroscopic studies. Assuming that the stream stars have the same Fe/H as the progenitor cluster, the derived Fe/H and values are used to estimate the possible Vlos range of the member stars at each location along the stream. Because of the heavy contamination of the field MW stars, the estimated Vlos range depends on prior assumptions about the stream's , which highlights the importance of more definitely identifying the member stars using proper motion and chemical abundances to obtain unbiased information of Vlos in the outer part of the Pal 5 stream. The models for the gravitational potential of the MW's dark matter halo that are compatible with the estimated Vlos range are discussed.
This study involved an analysis of the influence of liquid sloshing on the dynamics of flexible space structures with liquid on-board by considering the main body of a spacecraft as a rigid tank, the ...flexible appendages as two elastic beams, and on-board liquid as an ideal liquid. The meniscus of the free surface of the liquid due to surface tension was considered. The Lagrangians of the main body of the spacecraft (rigid tank), liquid, and two beams (flexible appendages) were used in addition to assuming symmetric motion of the system; the frequency equations of the coupled system were obtained by applying the Rayleigh–Ritz method. The influence of sloshing motion on the motions of the main body and flexible appendages of the spacecraft was investigated. The results indicated that the vibration characteristics of the coupled system were dependent on the static contact angle of the liquid, irrespective of whether the angle was larger/smaller than θ0=90°.
•Influence of liquid sloshing on the dynamics of space structure was clarified.•Meniscus of free surface was considered.•Dynamics of the system is dependent on the contact angle of meniscus.
A snake-like robot can move in not only the dry ground but also various viscous environments of water, mud, and clay by exhibiting undulating motions. To construct the numerical model including the ...fluid–structure interaction for the snake-like robot under the above-mentioned environments, the added mass and drag coefficients for the snake-like robot must be identified via experimentation because they depend on the shape of the body, the roughness of the skin, and the viscosity of the fluid. In this work, firstly, we performed experiments in which a snake-like robot of eight links exhibits swimming motions in three fluids of different kinematic viscosities, and we measured its joint positions during swimming. Subsequently, we proposed a numerical model of the snake-like robot swimming in fluids with a wide range of viscosities, and the identification method of some unknown fluid force parameters using an unscented Kalman filter. After that, we identified the unknown added mass and drag coefficients for the fluid force acting on the snake-like robot by using the proposed method. Then, we clarified that the appropriate drag model is the inertia drag model for water with small viscosity and the viscous drag model for oil which is a highly viscous fluid. Moreover, we confirmed that the undulation increased the tangential drag force along the body by 1.4 times. The position and velocity of the center of gravity of the snake-like robot, calculated using the numerical models, also agreed with the experimental results.
In this study, we analyzed the influence of liquid sloshing on the pitching dynamics of flexible space structure with liquid on-board; the analysis considers the main body of a spacecraft as a rigid ...tank, the flexible appendages as two elastically supported elastic beams, and on-board liquid as an ideal liquid. The meniscus of the free surface of the liquid due to surface tension was considered. The Lagrangians of the main body of the spacecraft (rigid tank), liquid, and two beams (flexible appendages) were used in addition to assuming antisymmetric motion of the system; the frequency equations of the coupled system were obtained by applying the Rayleigh–Ritz method. Influence of moment of inertia of the main body on coupled motions of the flexible spacecraft was investigated.
•Influence of liquid sloshing on the pitching dynamics of space structure was clarified.•Meniscus of free surface was considered.•Dynamics of the system is dependent on the moment of inertia of a main body of spacecraft.
During orthodontic tooth movement, the activation of the vascular system in the compressed periodontal ligament (PDL) is an indispensable process in tissue remodeling. We hypothesized that ...compressive force would induce angiogenesis of PDL through the production of vascular endothelial growth factor (VEGF). We examined the localization of VEGF in rat periodontal tissues during experimental tooth movement in vivo, and the effects of continuous compressive force on VEGF production and angiogenic activity in human PDL cells in vitro. PDL cells adjacent to hyalinized tissue and alveolar bone on the compressive side showed marked VEGF immunoreactivity. VEGF mRNA expression and production in PDL cells increased, and conditioned medium stimulated tube formation. These results indicate that continuous compressive force enhances VEGF production and angiogenic activity in PDL cells, which may contribute to periodontal remodeling, including angiogenesis, during orthodontic tooth movement.
Ionising radiation (IR) causes DNA (deoxyribonucleic acid) injury and activates intracellular signal pathways including the regulation of DNA repair and cell cycle. However, the further knowledge of ...molecular events involved in radiation exposure is essential to more comprehensively understand the effects of irradiation. Therefore, the gene expressions of mRNA (messenger ribonucleic acid) by X-ray irradiation in human B lymphoblast cell line (IM-9) using a microarray were investigated. The mRNA expressions of 65 genes were shown to be up-regulated at >2.0-fold in irradiated cells (4 Gy) when compared with non-irradiated cells (0 Gy) by microarray analysis. Among 65 genes, a large number of genes were up-regulated with an X-ray dose-dependent change. These results indicate that the up-regulation of their mRNAs is the effects of irradiation and may be due to biological dosimetric markers for the evaluation of radiation exposure in the future.
The purpose of this study was to evaluate abnormal magnetic resonance imaging (MRI) findings related to temporomandibular joint (TMJ) pain. This study included 245 joints of 152 patients with ...temporomandibular disorders with anterior disc displacement; of these, 129 joints had joint pain whereas 116 joints had no joint pain. MRI was used to evaluate the reduction of anterior disc displacement, joint effusion, mandible condylar morphology, bone marrow oedema of the mandibular condyle, and signal intensity of the posterior disc attachment (PDA) on fat-suppressed T2-weighted images. The odds ratio (OR) for each MRI variable for the pain group versus the no pain group was computed using logistic regression analysis. Univariate logistic regression analysis showed significant correlations between TMJ pain and all MRI findings. Multivariate logistic regression analysis showed significant correlations with joint effusion (P=0.03, OR 2.21), bone marrow oedema (P<0.001, OR 11.75), and signal intensity of the PDA (P<0.001, OR 6.21). These results suggest that bone marrow oedema, high signal intensity of the PDA on fat-suppressed T2-weighted images, and joint effusion, in descending order of influence, are factors related to TMJ pain.
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