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"Nishimoto, Shimpei"
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Observations of DNC and DCO+ toward the ∫-shaped Filament and Starless Cores in the Orion Molecular Clouds
2026
Although the deuterium fraction is known to be a powerful evolutionary tracer, its variation within individual molecular cloud cores is still poorly understood. The northern ∫-shaped filament and 20 individual starless cores in the Orion A and B clouds were mapped in the deuterated molecules of DNC and DCO+ with the receiver 7BEE installed on the Nobeyama 45 m radio telescope. In a ∼5′×30′ map of the northern ∫-shaped filament in the Orion A cloud, the DNC emission is detected over the filament, whereas the DCO+ emission is localized toward OMC-3, the northernmost region of the filament. The difference in distribution between DNC and DCO+ can be attributed to that between N- and C-bearing molecules as previously suggested by K. Tatematsu et al. (2008). High DNC/HN13C column density ratios were observed in OMC-2 and OMC-3, and low ratios in OMC-1. It seems that OMC-2 and OMC-3 still contain molecular gas close to the onset of star formation. In 3′×3′ maps of the individual starless cores in Orion, the column density ratios of DNC/HN13C and DCO+/H13CO+ were found to be rather constant locally within each core, although the core-to-core variation is not small. Similar timescales of deuterization, depletion, and dynamical evolution might explain the locally constant ratio.
Journal Article
Infrared bubble recognition in the Milky Way and beyond using deep learning
by
Kawanishi, Yasutomo
,
Miyamoto, Yusuke
,
Tokuda, Kazuki
in
Bubbles
,
Clustering
,
Data acquisition
2025
We propose a deep learning model that can detect Spitzer bubbles accurately using two-wavelength near-infrared data acquired by the Spitzer Space Telescope and JWST. The model is based on the Single Shot MultiBox Detector as an object detection model, trained and validated using Spitzer bubbles identified by the Milky Way Project (MWP-Bubble). We found that using only MWP-Bubbles with clear structures, along with normalization and data augmentation, significantly improved performance. To reduce the dataset bias, we also use the data without bubbles in the dataset selected by combining two techniques: negative sampling and clustering. The model was optimized by hyperparameter tuning using Bayesian optimization. Applying this model to a test region of the Galactic plane resulted in a 98 \\(\\%\\) detection rate for MWP-Bubbles with 8 \\(\\) m emission clearly encompassing 24 \\(\\) m emission. Additionally, we applied the model to a broader area of \\(1^ |l| 65^\\), \\(|b| 1^\\), including both training and validation regions, and the model detected 3,006 bubbles, of which 1,413 were newly detected. We also attempted to detect bubbles in the high-mass star-forming region Cygnus \\(X\\), as well as in the external galaxies Large Magellanic Cloud (LMC) and NGC 628. The model successfully detected Spitzer bubbles in these external galaxies, though it also detected Mira-type variable stars and other compact sources that can be difficult to distinguish from Spitzer bubbles. The detection process takes only a few hours, demonstrating the efficiency in detecting bubble structures. Furthermore, the method used for detecting Spitzer bubbles was applied to detect shell-like structures observable only in the 8 \\(\\) m emission band, leading to the detection of 469 shell-like structures in the LMC and 143 in NGC 628.
Observations of DNC and DCO\\(^+\\) toward the \\(ınt\\)-shaped Filament and Starless Cores in the Orion Molecular Clouds
2026
Although the deuterium fraction is known to be a powerful evolutionary tracer, its variation within individual molecular cloud cores is still poorly understood. The northern \\(ınt\\)-shaped filament and 20 individual starless cores in the Orion A and B clouds were mapped in the deuterated molecules of DNC and DCO\\(^+\\) with the Receiver 7BEE installed on the Nobeyama 45~m radio telescope. In a ~ 5' X 30' map of the northern \\(ınt\\)-shaped filament in the Orion A cloud, the DNC emission is detected over the filament, whereas the DCO\\(^+\\) emission is localized toward OMC-3, the northernmost region of the filament. The difference in distribution between DNC and DCO\\(^+\\) can be attributed to that between N- and C-bearing molecules as previously suggested by Tatematsu et al. High DNC/HN\\(^13\\)C column density ratios were observed in OMC-2 and OMC-3, and low ratios in OMC-1. It seems that OMC-2 and OMC-3 still contain molecular gas close to the onset of star formation. In 3' X 3' maps of the individual starless cores in Orion, the column density ratios of DNC/HN\\(^13\\)C and DCO\\(^+\\)/H\\(^13\\)CO\\(^+\\) are found to be rather constant locally within each core, although the core-to-core variation is not small. Similar timescales of deuterization, depletion, and dynamical evolution might explain the locally constant ratio.
Distance determination of molecular clouds in the 1st quadrant of the Galactic plane using deep learning : I. Method and Results
by
Ueda, Shota
,
Kawanishi, Yasutomo
,
Tokuda, Kazuki
in
Algorithms
,
Annotations
,
Artificial neural networks
2022
Machine learning has been successfully applied in varied field but whether it is a viable tool for determining the distance to molecular clouds in the Galaxy is an open question. In the Galaxy, the kinematic distance is commonly employed as the distance to a molecular cloud. However, there is a problem in that for the inner Galaxy, two different solutions, the ``Near'' solution, and the ``Far'' solution, can be derived simultaneously. We attempted to construct a two-class (``Near'' or ``Far'') inference model using a Convolutional Neural Network (CNN), a form of deep learning that can capture spatial features generally. In this study, we used the CO dataset toward the 1st quadrant of the Galactic plane obtained with the Nobeyama 45-m radio telescope (l = 62-10 degree, |b| < 1 degree). In the model, we applied the three-dimensional distribution (position-position-velocity) of the 12CO (J=1-0) emissions as the main input. The dataset with ``Near'' or ``Far'' annotation was made from the HII region catalog of the infrared astronomy satellite WISE to train the model. As a result, we could construct a CNN model with a 76% accuracy rate on the training dataset. By using the model, we determined the distance to molecular clouds identified by the CLUMPFIND algorithm. We found that the mass of the molecular clouds with a distance of < 8.15 kpc identified in the 12CO data follows a power-law distribution with an index of about -2.3 in the mass range of M >10^3 Msun. Also, the detailed molecular gas distribution of the Galaxy as seen from the Galactic North pole was determined.
Development of a new wideband heterodyne receiver system for the Osaka 1.85-m mm-submm telescope -- Corrugated horn & Optics covering 210-375 GHz band
2021
The corrugated horn is a high performance feed often used in radio telescopes. There has been a growing demand for wideband optics and corrugated horns in millimeter and submillimeter-wave receivers. It improves the observation efficiency and allows us to observe important emission lines such as CO in multiple excited states simultaneously. However, in the millimeter/submillimeter band, it has been challenging to create a conical corrugated horn with a fractional bandwidth of ~60% because the wavelength is very short, making it difficult to make narrow corrugations. In this study, we designed a conical corrugated horn with good return loss, low cross-polarization, and symmetric beam pattern in the 210-375GHz band (56% fractional bandwidth) by optimizing the dimensions of the corrugations. The corrugated horn was installed on the Osaka 1.85-m mm-submm telescope with the matched frequency-independent optics, and simultaneous observations of 12CO, 13CO, and C18O (J = 2-1, 3-2) were successfully made. In this paper, we describe the new design of the corrugated horn and report the performance evaluation results including the optics.
Development of a new wideband heterodyne receiver system for the Osaka 1.85-m mm-submm telescope -- Receiver development & the first light of simultaneous observation in 230GHz and 345GHz bands with an SIS-mixer with 4-21GHz IF output
2021
We have developed a wideband receiver system for simultaneous observations in CO lines of J = 2-1 and J = 3-2 transitions using the Osaka 1.85-m mm-submm telescope. As a frequency separation system, we developed multiplexers that connect three types of diplexers, each consisting of branch-line couplers and high-pass filters. The radio frequency (RF) signal is eventually distributed into four frequency bands, each of which is fed to a superconductor-insulator-superconductor (SIS) mixer. The RF signal from the horn is divided into two frequency bands by a wideband diplexer with a fractional bandwidth of 56%, and then each frequency band is further divided into two bands by each diplexer. The developed multiplexers were designed, fabricated, and characterized using a vector network analyzer. The measurement results showed good agreement with the simulation. The receiver noise temperature was measured by connecting the SIS-mixers, one of which has a wideband 4-21GHz intermediate frequency (IF) output. The receiver noise temperatures were measured to be ~70K in the 220GHz band, ~100K in the 230GHz band, 110-175K in the 330GHz band, and 150-250K in the 345GHz band. This receiver system has been installed on the 1.85-m telescope at the Nobeyama Radio Observatory. We succeeded in the simultaneous observations of six CO isotopologue lines with the transitions of J = 2-1 and J = 3-2 toward the Orion KL as well as the on-the-fly (OTF) mappings toward the Orion KL and W 51.
Predicting reliable H\\(_2\\) column density maps from molecular line data using machine learning
by
Ueda, Shota
,
Kawanishi, Yasutomo
,
Tokuda, Kazuki
in
Carbon monoxide
,
Density
,
Machine learning
2023
The total mass estimate of molecular clouds suffers from the uncertainty in the H\\(_2\\)-CO conversion factor, the so-called \\(X_ CO\\) factor, which is used to convert the \\(^12\\)CO (1--0) integrated intensity to the H\\(_2\\) column density. We demonstrate the machine learning's ability to predict the H\\(_2\\) column density from the \\(^12\\)CO, \\(^13\\)CO, and C\\(^18\\)O (1--0) data set of four star-forming molecular clouds; Orion A, Orion B, Aquila, and M17. When the training is performed on a subset of each cloud, the overall distribution of the predicted column density is consistent with that of the Herschel column density. The total column density predicted and observed is consistent within 10\\%, suggesting that the machine learning prediction provides a reasonable total mass estimate of each cloud. However, the distribution of the column density for values \\(> 2 10^22\\) cm\\(^-2\\), which corresponds to the dense gas, could not be predicted well. This indicates that molecular line observations tracing the dense gas are required for the training. We also found a significant difference between the predicted and observed column density when we created the model after training the data on different clouds. This highlights the presence of different \\(X_ CO\\) factors between the clouds, and further training in various clouds is required to correct for these variations. We also demonstrated that this method could predict the column density toward the area not observed by Herschel if the molecular line and column density maps are available for the small portion, and the molecular line data are available for the larger areas.
Current status and future plan of Osaka Prefecture University 1.85-m mm-submm telescope project
by
Tokuda, Kazuki
,
Kawashita, Sana
,
Fujita, Shinji
in
Altitude
,
Angular resolution
,
Chemical properties
2020
We report the current status of the 1.85-m mm-submm telescope installed at the Nobeyama Radio Observatory (altitude 1400 m) and the future plan. The scientific goal is to reveal the physical/chemical properties of molecular clouds in the Galaxy by obtaining large-scale distributions of molecular gas with an angular resolution of several arcminutes. A semi-automatic observation system created mainly in Python on Linux-PCs enables effective operations. A large-scale CO \\(J=\\)2--1 survey of the molecular clouds (e.g., Orion-A/B, Cygnus-X/OB7, Taurus-California-Perseus complex, and Galactic Plane), and a pilot survey of emission lines from minor molecular species toward Orion clouds have been conducted so far. The telescope also is providing the opportunities for technical demonstrations of new devices and ideas. For example, the practical realizations of PLM (Path Length Modulator) and waveguide-based sideband separating filter, installation of the newly designed waveguide-based circular polarizer and OMT (Orthomode Transducer), and so on. As the next step, we are now planning to relocate the telescope to San Pedro de Atacama in Chile (altitude 2500 m), and are developing very wideband receiver covering 210--375 GHz (corresponding to Bands 6--7 of ALMA) and full-automatic observation system. The new telescope system will provide large-scale data in the spatial and frequency domain of molecular clouds of Galactic plane and Large/Small Magellanic Clouds at the southern hemisphere. The data will be precious for the comparison with those of extra-galactic ones that will be obtained with ALMA as the Bands 6/7 are the most efficient frequency bands for the surveys in extra-galaxies for ALMA.
Association between the Perception of Behavior Change and Habitual Exercise during COVID-19: A Cross-Sectional Online Survey in Japan
by
Makizako, Hyuma
,
Nishio, Ikuko
,
Nishimoto, Daisaku
in
Cardiovascular disease
,
Coronaviruses
,
COVID-19
2023
In general, the perception of behavior change may be associated with habitual exercise. However, this association might not be well-understood due to the state of emergency of the COVID-19 pandemic. This study collected data from 1499 internet users aged 20–86 years living in Japan who participated in the online survey from 26 to 27 February 2021. Having a perception of behavior change was defined as preparation, action, and maintenance of the transtheoretical model. The habitual exercise was defined as 600 metabolic equivalent min/week or more based on the International Physical Activity Questionnaire. Multivariate logistic regression analysis was used to calculate the odds ratio of habitual exercise and a 95% confidence interval was estimated after adjusting for related factors. We found that perception of behavior change was positively associated with habitual exercise (adjusted odds ratio = 2.41, 95%CI = 1.89–3.08), and similar associations were found in states of emergency (2.69, 1.97–3.69) and non-emergency (2.01, 1.34–3.01). Moreover, women were negatively associated in all analyses with habitual exercise compared to men (0.63, 0.49–0.80; 0.65, 0.44–0.96; 0.62, and 0.45–0.84, respectively). Thus, the perception of behavior change may be involved in the implementation of habitual exercise, suggesting that women face difficulties in engaging in habitual exercise.
Journal Article
Effects of a non-cyclodextrin cyclic carbohydrate on mouse melanoma cells: Characterization of a new type of hypopigmenting sugar
by
Matsumoto, Yohsuke
,
Hanaya, Toshiharu
,
Ushio, Shimpei
in
Analysis
,
Animals
,
Biology and Life Sciences
2017
Cyclic nigerosyl nigerose (CNN) is a cyclic tetrasaccharide that exhibits properties distinct from other conventional cyclodextrins. Herein, we demonstrate that treatment of B16 melanoma with CNN results in a dose-dependent decrease in melanin synthesis, even under conditions that stimulate melanin synthesis, without significant cytotoxity. The effects of CNN were prolonged for more than 27 days, and were gradually reversed following removal of CNN. Undigested CNN was found to accumulate within B16 cells at relatively high levels. Further, CNN showed a weak but significant direct inhibitory effect on the enzymatic activity of tyrosinase, suggesting one possible mechanism of hypopigmentation. While a slight reduction in tyrosinase expression was observed, tyrosinase expression was maintained at significant levels, processed into a mature form, and transported to late-stage melanosomes. Immunocytochemical analysis demonstrated that CNN treatment induced drastic morphological changes of Pmel17-positive and LAMP-1-positive organelles within B16 cells, suggesting that CNN is a potent organelle modulator. Colocalization of both tyrosinase-positive and LAMP-1-positive regions in CNN-treated cells indicated possible degradation of tyrosinase in LAMP-1-positive organelles; however, that possibility was ruled out by subsequent inhibition experiments. Taken together, this study opens a new paradigm of functional oligosaccharides, and offers CNN as a novel hypopigmenting molecule and organelle modulator.
Journal Article