Modeling and sensory feedback control for space manipulators

The positioning control problem of the endtip of space manipulators whose base are uncontrolled is examined. In such a case, the conventional control method for industrial robots based on a local feedback at each joint is not applicable, because a solution of the joint displacements that satisfies a given position and orientation of the endtip is not decided uniquely. A sensory feedback control scheme for space manipulators based on an artificial potential defined in a task-oriented coordinates is proposed. Using this scheme, the controller can easily determine the input torque of each joint from the data of an external sensor such as a visual device. Since the external sensor is mounted on the unfixed base, the manipulator must track the moving image of the target in sensor coordinates. Moreover the dynamics of the base and the manipulator are interactive. However, the endtip is proven to asymptotically approach the stationary target in an inertial coordinate frame by the Liapunov's method. Finally results of computer simulation for a 6-link space manipulator model show the effectiveness of the proposed scheme

Interacting open p-branes

The Kalb-Ramond action, derived for interacting strings through an action-at-a-distance force, is generalized to the case of interacting p-dimensional objects (p-branes) in D-dimensional space-time. The open p-brane version of the theory is especially taken up. On account of the existence of their boundary surface, the fields mediating interactions between open p-branes are obtained as massive gauge fields, quite in contrast to massless gauge ones for closed p-branes.Comment: 10 pages, LaTe

Kalb-Ramond interaction for a closed p-brane

The Kalb-Ramond action for an interacting string is generalized to the case of a high-dimensional object (p-brane). The interaction is found to be mediated by a gauge boson of a completely antisymmetric tensor of rank $p+1$.Comment: 7 page

Protective Effects of Rosa damascena and Its Active Constituent on Aβ(25–35)-Induced Neuritic Atrophy

Dementia is a clinical syndrome characterized by multiple cognitive deficits and causes progressive neurodegeneration leading eventually to death. The incidence of dementia is increasing worldwide with the increase in ageing population. However, no effective treatment is available yet. It has been hypothesized that drugs activating neurite outgrowth might induce neuronal reconstruction and help in the recovery of brain function. Working on this hypothesis, we recently observed that the chloroform extract of the Rosa damascena significantly induced the neurite outgrowth activity and inhibited the Aβ(25–35)-induced atrophy and cell death. Further workup led the isolation of a very long polyunsaturated fatty acid having molecular formula C37H64O2 as an active constituent. The structure of this compound was established by extensive analysis of fragmentations observed in EI-MS mode. The isolated compound protected Aβ(25–35)-induced atrophy and displayed strong neurite outgrowth activity. The length of dendrite in the cells treated with this compound were comparable to those of nerve growth factor (NGF) treated cells

Development of Assembly Robot System for Flexible Belt-Shaped Subject

We develop an assembly robot system for assembling the flexible belt-shaped subject. An image processing method is developed to recognize the belt-shaped subject. This method is able to determine the grasping point and grasping angle for piking up a subject by a multiple hands unit. CAD information is used to determine the grasping point. The multiple hands unit is developed, which is able to grasp all grasping points of a subject at a time. In addition, the image processing method is used to judge whether a subject is fastened accurately at right position or not during the assembly

Molecular characterization of Mybbp1a as a co-repressor on the Period2 promoter

The circadian clock comprises transcriptional feedback loops of clock genes. Cryptochromes are essential components of the negative feedback loop in mammals as they inhibit CLOCK-BMAL1-mediated transcription. We purified mouse CRY1 (mCRY1) protein complexes from Sarcoma 180 cells to determine their roles in circadian gene expression and discovered that Myb-binding protein 1a (Mybbp1a) interacts with mCRY1. Mybbp1a regulates various transcription factors, but its role in circadian gene expression is unknown. We found that Mybbp1a functions as a co-repressor of Per2 expression and repressed Per2 promoter activity in reporter assays. Chromatin immunoprecipitation (ChIP) assays revealed endogenous Mybbp1a binding to the Per2 promoter that temporally matched that of mCRY1. Furthermore, Mybbp1a binding to the Per2 promoter correlated with the start of the down-regulation of Per2 expression and with the dimethylation of histone H3 Lys9, to which it could also bind. These findings suggest that Mybbp1a and mCRY1 can form complexes on the Per2 promoter that function as negative regulators of Per2 expression

Hybrid mode atomic force microscopy of phase modulation and frequency modulation

This is a pre-copyedited, author-produced version of an article accepted for publication in Microscopy following peer review. The version of record Yamamoto T., Miyazaki M., Nomura H., et al. Hybrid mode atomic force microscopy of phase modulation and frequency modulation. 72(3), 236-242 1 June 2023 is available online at: https://doi.org/10.1093/jmicro/dfac057.We propose hybrid phase modulation (PM)/frequency modulation (FM) atomic force microscopy (AFM) to increase the imaging speed of AFM in high-Q environments. We derive the relationship between the phase shift, the frequency shift and the tip-sample interaction force from the equation of motion for the cantilever in high-Q environments. The tip-sample conservative force is approximately given by the sum of the conservative force with respect to the phase shift in the PM mode and that with respect to the frequency shift in the FM mode. We preliminarily demonstrate that the hybrid PM/FM-AFM is a new and very promising AFM operation mode that can increase imaging speed

Enhancement of the Bonding Durability of Resin-based Cement to Lithium Disilicate Glass Ceramics Using Surface Modification Methods

The aim of the present study was undertaken to investigate the effects of several surface modification methods applied to lithium disilicate glass ceramics (LDCs) on their bonding durability with resin-based cement. The LDC specimens were sectioned using a low-speed diamond cutting machine, crystallized by heating in a furnace, and then subjected to several surface modification treatments such as acid etching, sandblasting, or silica coating with silane coupling agents. Then, a cylindrical titanium with a sandblasted surface was bonded to the surface-modified LDC specimens using resin-based cement. After being either stored in water at 37°C for 24h or subjected to 10,000 and/or 30,000 thermal cycles, the specimens were subjected to a shear bond strength test using a universal testing machine. The surface-modified LDC specimens obtained by combining blasting and silica coating modification treatments showed excellent durability, similar to that of acid-etched specimens. For safer laboratory practice, we recommend using the silica coating method for LDCs prior to applying silane coupling agents

Large-scale Filamentary Structure around the Protocluster at Redshift z=3.1

We report the discovery of a large-scale coherent filamentary structure of Lyman alpha emitters in a redshift space at z=3.1. We carried out spectroscopic observations to map the three dimensional structure of the belt-like feature of the Lyman alpha emitters discovered by our previous narrow-band imaging observations centered on the protocluster at z=3.1. The feature was found to consist of at least three physical filaments connecting with each other. The result is in qualitative agreement with the prediction of the 'biased' galaxy-formation theories that galaxies preferentially formed in large-scale filamentary or sheet-like mass overdensities in the early Universe. We also found that the two known giant Lyman alpha emission-line nebulae showing high star-formation activities are located near the intersection of these filaments, which presumably evolves into a massive cluster of galaxies in the local Universe. This may suggest that massive galaxy formation occurs at the characteristic place in the surrounding large-scale structure at high redshift.Comment: 11 pages, 3 figures, accepted for publication in ApJ Letter

The Halpha Luminosity Function of the Galaxy Cluster Abell 521 at z = 0.25

We present an optical multicolor-imaging study of the galaxy cluster Abell 521 at $z = 0.25$, using Suprime-Cam on the Subaru Telescope, covering an area of $32 \times 20$ arcmin$^2$ ($9.4 \times 5.8 h_{50}^{-2}$ Mpc$^2$ at $z = 0.25$). Our imaging data taken with both a narrow-band filter, $NB816$ ($\lambda_0 = 8150$\AA and $\Delta \lambda = 120$\AA), and broad-band filters, $B,V,R_{\rm C}, i^\prime$, and $z^\prime$ allow us to find 165 H$\alpha$ emitters. We obtain the H$\alpha$ luminosity function (LF) for the cluster galaxies within 2 Mpc; the Schechter parameters are $\alpha = -0.75 \pm 0.23$, $\phi^\star = 10^{-0.25 \pm 0.20}$ Mpc$^{-3}$, and $L^\star = 10^{42.03 \pm 0.17}$ erg s$^{-1}$. Although the faint end slope, $\alpha$, is consistent with that of the local cluster H$\alpha$ LFs, the characteristic luminosity, $L^\star$, is about 6 times (or $\approx 2$ mag) brighter. This strong evolution implies that Abell 521 contains more active star-forming galaxies than the local clusters, being consistent with the observed Butcher-Oemler effect. However, the bright $L^\star$ of Abell 521 may be, at least in part, due to the dynamical condition of this cluster.Comment: 21 pages, 7 figures, ApJ, Part 1, in pres