Predictor Order and Error Distribution of MMAE Predictors for Lossless Image Coding

This paper investigates the relation between error distribution and predictive order of minimum mean abusolute error predictors (MMAE predictors) designed for lossless coding of grayscale images. Design of MMAE predictors reduces to the linear programming problem. Let k be the number of coefficients in a predictor (predictor order), we imagine that predictor order k may have a distribution shaping effect. Main purpose of this paper is to ensure that k has such an effect

A survey of T Tauri stars with AKARI toward the Taurus-Auriga region

Aims: We search new T Tauri star (TTS) candidates with the mid-infrared (MIR) part of the AKARI All-Sky Survey at 9 and 18 um wavelengths. Methods: We used the point source catalogue (PSC), obtained by the Infrared Camera (IRC) on board AKARI. We combined the 2MASS PSC and the 3rd version of the USNO CCD Astrograph Catalogue (UCAC) with the AKARI IRC-PSC, and surveyed 517 known TTSs over a 1800-square-degree part of the Taurus-Auriga region to find criteria to extract TTSs. We considered asymptotic giant branch (AGB) stars, post-AGB stars, Planetary Nebulae (PNe), and galaxies, which have similar MIR colours, to separate TTSs from these sources. Results: Of the 517 known TTSs, we detected 133 sources with AKARI. Based on the colour-colour and colour-magnitude diagrams made from the AKARI, 2MASS, and UCAC surveys, we propose the criteria to extract TTS candidates from the AKARI All-Sky data. On the basis of our criteria, we selected 176/14725 AKARI sources as TTS candidates which are located around the Taurus-Auriga region. Comparing these sources with SIMBAD, there are 148 previously identified sources including 115 Young Stellar Objects (YSOs), and 28 unidentified sources. Conclusions: Based on SIMBAD identifications, we take the TTS-identification probability using our criteria to be ~75 %. We find 28 TTS candidates, of which we expect 21 to be confirmed once follow-up observations can be obtained. Although the probability of ~75 % is not so high, it is affected by the completeness of the SIMBAD database, and we can search for TTSs over the whole sky, over all star forming regions.Comment: 12 pages, 9 figures, accepted for publication in A&

In vivo Magnetic Resonance Microscopy and Hypothermic Anaesthesia of a Disease Model in Medaka

In medical and pharmacological research, various human disease models in small fish, such as medaka (Oryzias latipes), have been created. To investigate these disease models noninvasively, magnetic resonance imaging (MRI) is suitable because these small fish are no longer transparent as adults. However, their small body size requires a high spatial resolution, and a water pool should be avoided to maximize the strength of MRI. We developed in vivo magnetic resonance microscopy (MR microscopy) without a water pool by combining hypothermic anaesthesia and a 14.1 T MR microscope. Using in vivo MR microscopy, we noninvasively evaluated the hepatic steatosis level of a non-alcoholic fatty liver disease model in medaka and followed the individual disease progression. The steatosis level was quantified by the MRI-estimated proton density fat-fraction (MRI-PDFF), which estimates the triglyceride fat concentration in liver tissue and is recognized as an imaging biomarker. The MRI-PDFF results agreed with a histological analysis. Moreover, we optimized the hypothermic anaesthesia procedure to obtain a recovery proportion of 1 in the experiment involving MR microscopy. Recovered medaka could not be distinguished from naïve medaka after the experiment. Therefore, the in vivo MR microscopy will expand the possibilities of a human disease model in fish

Detection of an H-alpha Emission Line on a Quasar, RX J1759.4+6638, at z=4.3 with AKARI

We report the detection of an H-alpha emission line in the low resolution spectrum of a quasar, RX J1759.4+6638, at a redshift of 4.3 with the InfraRed Camera (IRC) onboard the AKARI. This is the first spectroscopic detection of an H-alpha emission line in a quasar beyond z=4. The overall spectral energy distribution (SED) of RX J1759.4+6638 in the near- and mid-infrared wavelengths agrees with a median SED of the nearby quasars and the flux ratio of F(Ly-alpha)/F(H-alpha) is consistent with those of previous reports for lower-redshift quasars.Comment: 9pages, 3 figures, Publications of the Astronomical Society of Japan, in pres

Fermi level tuning of Ag-doped Bi2Se3 topological insulator

The temperature dependence of the resistivity (rho) of Ag-doped Bi2Se3 (AgxBi2-xSe3) shows insulating behavior above 35 K, but below 35 K, rho suddenly decreases with decreasing temperature, in contrast to the metallic behavior for non-doped Bi2Se3 at 1.5-300 K. This significant change in transport properties from metallic behavior clearly shows that the Ag doping of Bi2Se3 can effectively tune the Fermi level downward. The Hall effect measurement shows that carrier is still electron in AgxBi2-xSe3 and the electron density changes with temperature to reasonably explain the transport properties. Furthermore, the positive gating of AgxBi2-xSe3 provides metallic behavior that is similar to that of non-doped Bi2Se3, indicating a successful upward tuning of the Fermi level

Near-infrared and Mid-infrared Spectroscopy with the Infrared Camera (IRC) for AKARI

The Infrared Camera (IRC) is one of the two instruments on board the AKARI satellite. In addition to deep imaging from 1.8-26.5um for the pointed observation mode of the AKARI, it has a spectroscopic capability in its spectral range. By replacing the imaging filters by transmission-type dispersers on the filter wheels, it provides low-resolution (lambda/d_lambda ~ 20-120) spectroscopy with slits or in a wide imaging field-of-view (approximately 10'X10'). The IRC spectroscopic mode is unique in space infrared missions in that it has the capability to perform sensitive wide-field spectroscopic surveys in the near- and mid-infrared wavelength ranges. This paper describes specifications of the IRC spectrograph and its in-orbit performance.Comment: 13 pages, 7 figures, accepted for publication on PAS

CDK8/19 inhibition plays an important role in pancreatic β-cell induction from human iPSCs

サイクリン依存性キナーゼCDK8/19阻害はヒトiPS細胞からの膵島様細胞への分化誘導において重要な役割を果たす. 京都大学プレスリリース. 2023-02-27.A safer method of generating pancreatic islet-like cells from human iPS cells by inhibiting cyclin-dependent kinase CDK8/19. 京都大学プレスリリース. 2023-03-08.[Background] Transplantation of differentiated cells from human-induced pluripotent stem cells (hiPSCs) holds great promise for clinical treatments. Eliminating the risk factor of malignant cell transformation is essential for ensuring the safety of such cells. This study was aimed at assessing and mitigating mutagenicity that may arise during the cell culture process in the protocol of pancreatic islet cell (iPIC) differentiation from hiPSCs. [Methods] We evaluated the mutagenicity of differentiation factors used for hiPSC-derived pancreatic islet-like cells (iPICs). We employed Ames mutagenicity assay, flow cytometry analysis, immunostaining, time-resolved fluorescence resonance energy transfer-based (TR-FRET) cell-free dose–response assays, single-cell RNA-sequencing and in vivo efficacy study. [Results] We observed a mutagenic effect of activin receptor-like kinase 5 inhibitor II (ALK5iII). ALK5iII is a widely used β-cell inducer but no other tested ALK5 inhibitors induced β-cells. We obtained kinase inhibition profiles and found that only ALK5iII inhibited cyclin-dependent kinases 8 and 19 (CDK8/19) among all ALK5 inhibitors tested. Consistently, CDK8/19 inhibitors efficiently induced β-cells in the absence of ALK5iII. A combination treatment with non-mutagenic ALK5 inhibitor SB431542 and CDK8/19 inhibitor senexin B afforded generation of iPICs with in vitro cellular composition and in vivo efficacy comparable to those observed with ALK5iII. [Conclusion] Our findings suggest a new risk mitigation approach for cell therapy and advance our understanding of the β-cell differentiation mechanism