المؤلفون: Geem, Jooyeon, Ishiguro, Masateru, Naito, Hiroyuki, Hasegawa, Sunao, Takahashi, Jun, Bach, Yoonsoo P., Jin, Sunho, Takagi, Seiko, Ono, Tatsuharu, Kuroda, Daisuke, Sekiguchi, Tomohiko, Kuramoto, Kiyoshi, Nakamura, Tomoki, Watanabe, Makoto

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics

الوصف: Context. Ch-type asteroids are distinctive among other dark asteroids in that they exhibit deep negative polarization branches (NPBs). Nevertheless, the physical and compositional properties that cause their polarimetric distinctiveness are less investigated. Aims. We aim to investigate the polarimetric uniqueness of Ch-type asteroids by making databases of various observational quantities (i.e., spectroscopic and photometric properties as well as polarimetric ones) of dark asteroids.Methods. We conducted an intensive polarimetric survey of 52 dark asteroids (including 31 Ch-type asteroids) in the R$_\mathrm{C}$-band to increase the size of polarimetric samples. The observed data are compiled with previous polarimetric, spectroscopic, and photometric archival data to find their correlations. Results. We find remarkable correlations between these observed quantities, particularly the depth of NPBs and their spectroscopic features associated with the hydrated minerals. The amplitude of the opposition effect in photometric properties also shows correlations with polarimetric and spectral properties. However, these observed quantities do not show noticeable correlations with the geometric albedo, thermal inertia, and diameter of asteroids. Conclusions. Based on the observational evidence, we arrive at our conclusion that the submicrometer-sized structures (fibrous or flaky puff pastry-like structures in phyllosilicates) in the regolith particles could contribute to the distinctive NPBs of hydrated asteroids.
Comment: 25 pages, 10 figures (Accepted for the publication of Astronomy and Astrophysics on May 30, 2024)

الوصول الحر: http://arxiv.org/abs/2406.00319Test

المؤلفون: Lomax, Jamie R., Wisniewski, John P., Grady, Carol A., McElwain, Michael W., Hashimoto, Jun, Kudo, Tomoyuki, Kusakabe, Nobuhiko, Okamoto, Yoshiko K., Fukagawa, Misato, Abe, Lyu, Brandner, Wolfgang, Brandt, Timothy D., Carson, Joseph C., Currie, Thayne M, Egner, Sebastian, Feldt, Markus, Goto, Miwa, Guyon, Olivier, Hayano, Yutaka, Hayashi, Masahiko, Hayashi, Saeko S., Henning, Thomas, Hodapp, Klaus W., Inoue, Akio, Ishii, Miki, Iye, Masanori, Janson, Markus, Kandori, Ryo, Knapp, Gillian R., Kuzuhara, Masayuki, Kwon, Jungmi, Matsuo, Taro, Mayama, Satoshi, Miyama, Shoken, Momose, Munetake, Morino, Jun-Ichi, Moro-Martin, Amaya, Nishimura, Tetsuo, Pyo, Tae-Soo, Schneider, Glenn H, Serabyn, Eugene, Sitko, Michael L., Suenaga, Takuya, Suto, Hiroshi, Suzuki, Ryuji, Takahashi, Yasuhiro H., Takami, Michihiro, Takato, Naruhisa, Terada, Hiroshi, Thalmann, Christian, Tomono, Daigo, Turner, Edwin L., Watanabe, Makoto, Yamada, Toru, Takami, Hideki, Usuda, Tomonori, Tamura, Motohide

مرشدي الرسالة: Univ Arizona, Steward Observ

مصطلحات موضوعية: planet-disk interactions, planetary systems, protoplanetary disks, radiative transfer, stars: individual (AB Aur), stars: pre-main sequence

الوصف: We present a new analysis of multi-epoch, H-band, scattered light images of the AB Aur system. We use a Monte Carlo radiative transfer code to simultaneously model the system's spectral energy distribution (SED) and H-band polarized intensity (PI) imagery. We find that a disk-dominated model, as opposed to one that is envelope-dominated, can plausibly reproduce AB Aur's SED and near-IR imagery. This is consistent with previous modeling attempts presented in the literature and supports the idea that at least a subset of AB Aur's spirals originate within the disk. In light of this, we also analyzed the movement of spiral structures in multi-epoch H-band total light and PI imagery of the disk. We detect no significant rotation or change in spatial location of the spiral structures in these data, which span a 5.8-year baseline. If such structures are caused by disk-planet interactions, the lack of observed rotation constrains the location of the orbit of planetary perturbers to be >47 au.

العلاقة: http://stacks.iop.org/0004-637X/828/i=1/a=2?key=crossref.3d2c6f18ef5537b557b848ddf53457b6Test

الإتاحة: http://hdl.handle.net/10150/622048Test
http://arizona.openrepository.com/arizona/handle/10150/622048Test

المؤلفون: Noda, Hirofumi, Mineta, Taisei, Minezaki, Takeo, Sameshima, Hiroaki, Kokubo, Mitsuru, Kawamuro, Taiki, Yamada, Satoshi, Horiuchi, Takashi, Matsumoto, Hironori, Watanabe, Makoto, Morihana, Kumiko, Itoh, Yoichi, Kawabata, Koji S., Fukazawa, Yasushi

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena

الوصف: "Changing-look active galactic nuclei" (CLAGNs) are known to change their apparent types between types 1 and 2, usually accompanied by a drastic change in their luminosity on timescales of years. However, it is still unclear whether materials in broad-line regions (BLRs) in CLAGNs appear and disappear during the type-transition or remain at the same location while the line production is simply activated or deactivated. Here we present our X-ray-optical monitoring results of a CLAGN, NGC 3516, by Suzaku, Swift, and ground telescopes, with our primary focus on the narrow Fe-K$\alpha$ emission line, which is an effective probe of the BLR materials. We detected significant variations of the narrow Fe-K$\alpha$ line on a timescale of tens of days during the type-2 (faint) phase in 2013-2014, and conducted "narrow Fe-K$\alpha$ reverberation mapping," comparing its flux variation with those of the X-ray continuum from a corona and $B$-band continuum from an accretion disk. We derived, as a result, a time lag of $10.1^{+5.8}_{-5.6}$ days ($1\sigma$ errors) for the Fe-K$\alpha$ line behind the continuum, which is consistent with the location of the BLR determined in optical spectroscopic reverberation mapping during the type-1 (bright) phase. This finding shows that the BLR materials remained at the same location without emitting optical broad-lines during the type-2 phase. Considering the drastic decrease of the radiation during the type-transition, our result is possibly inconsistent with the hotly-discussed formation models of the BLR which propose that the radiative pressure from an accretion disk should be the main driving force.
Comment: 15 pages, 7 figures, 3 tables, accepted for the publication in ApJ

الوصول الحر: http://arxiv.org/abs/2212.02731Test

المؤلفون: Naito, Hiroyuki, Tajitsu, Akito, Ribeiro, Valèrio A. R. M., Arai, Akira, Maehara, Hiroyuki, Kouzuma, Shinjirou, Iijima, Takashi, Okazaki, Atsuo T., Watanabe, Makoto, Takagi, Seiko, Watanabe, Fumitake, Sakon, Itsuki, Sadakane, Kozo

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics - High Energy Astrophysical Phenomena

الوصف: Morphology of nova ejecta is essential for fully understanding the physical processes involved in nova eruptions. We studied the 3D morphology of the expanding ejecta of the extremely slow nova V1280 Sco with a unique light curve. Synthetic line profile spectra were compared to the observed [O III] 4959, 5007 and [N II] 5755 emission line profiles in order to find the best-fit morphology, inclination angle, and maximum expansion velocity of the ejected shell. We derive the best fitting expansion velocity, inclination, and squeeze as $V_{\rm exp} = 2100^{+100}_{-100}$ \,km\,s$^{-1}$, $i = 80^{+1}_{-3}$ deg, and $squ = 1.0^{+0.0}_{-0.1}$ using [O III] line profiles, and $V_{\rm exp} = 1600^{+100}_{-100}$ \,km\,s$^{-1}$, $i = 81^{+2}_{-4}$ deg, and $squ = 1.0^{+0.0}_{-0.1}$ using [N II] 5755 line profile. A high inclination angle is consistent with the observational results showing multiple absorption lines originating from clumpy gases which are produced in dense and slow equatorially focused outflows. Based on additional observational features such as optical flares near the maximum light and dust formation on V1280 Sco, a model of internal shock interaction between slow ejecta and fast wind proposed for the $\gamma$-ray emission detected in other novae seems to be applicable to this extremely slow and peculiar nova. Increasing the sample size of novae whose morphology is studied will be helpful in addressing long-standing mysteries in novae such as the dominant energy source to power the optical light at the maximum, optical flares near the maximum, clumpiness of the ejecta, and dust formation.
Comment: 21 pages, 8 figures, accepted for publication in ApJ

الوصول الحر: http://arxiv.org/abs/2205.02266Test

المؤلفون: Ishiguro, Masateru, Bach, Yoonsoo P., Geem, Jooyeon, Naito, Hiroyuki, Kuroda, Daisuke, Im, Myungshin, Lee, Myung Gyoon, Seo, Jinguk, Jin, Sunho, Kwon, Yuna G., Oono, Tatsuharu, Takagi, Seiko, Sato, Mitsuteru, Kuramoto, Kiyoshi, Ito, Takashi, Hasegawa, Sunao, Yoshida, Fumi, Arai, Tomoko, Akitaya, Hiroshi, Sekiguchi, Tomohiko, Okazaki, Ryo, Imai, Masataka, Ohtsuka, Katsuhito, Watanabe, Makoto, Takahashi, Jun, Devogele, Maxime, Fedorets, Grigori, Siltala, Lauri, Granvik, Mikael

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics

الوصف: The investigation of asteroids near the Sun is important for understanding the final evolutionary stage of primitive solar system objects. A near-Sun asteroid, (155140) 2005 UD, has orbital elements similar to those of (3200) Phaethon (the target asteroid for the JAXA's $DESTINY^+$ mission). We conducted photometric and polarimetric observations of 2005 UD and found that this asteroid exhibits a polarization phase curve similar to that of Phaethon over a wide range of observed solar phase angles ($ \alpha = 20 - 105^\circ $) but different from those of (101955) Bennu and (162173) Ryugu (asteroids composed of hydrated carbonaceous materials). At a low phase angle ($\alpha \lesssim 30^\circ$), the polarimetric properties of these near-Sun asteroids (2005 UD and Phaethon) are consistent with anhydrous carbonaceous chondrites, while the properties of Bennu are consistent with hydrous carbonaceous chondrites. We derived the geometric albedo, $ p_\mathrm{V} \sim 0.1 $ (in the range of 0.088-0.109); mean $ V $-band absolute magnitude, $ H_\mathrm{V} = 17.54 \pm 0.02 $; synodic rotational period, $ T_\mathrm{rot} = 5.2388 \pm 0.0022 $ hours (the two-peaked solution is assumed); and effective mean diameter, $ D_\mathrm{eff} = 1.32 \pm 0.06 $ km. At large phase angles ($ \alpha \gtrsim 80^\circ$), the polarization phase curve are likely explained by the dominance of large grains and the paucity of small micron-sized grains. We conclude that the polarimetric similarity of these near-Sun asteroids can be attributed to the intense solar heating of carbonaceous materials around their perihelia, where large anhydrous particles with small porosity could be produced by sintering.
Comment: 15 pages, 9 figures, accepted for publication in Monthly Notices of Royal Astronomical Society (MNRAS)

الوصول الحر: http://arxiv.org/abs/2111.00152Test

المؤلفون: Geem, Jooyeon, Ishiguro, Masateru, Bach, Yoonsoo P., Kuroda, Daisuke, Naito, Hiroyuki, Hanayama, Hidekazu, Kim, Yoonyoung, Kwon, Yuna G., Jin, Sunho, Sekiguchi, Tomohiko, Okazaki, Ryo, Vaubaillon, Jeremie J., Imai, Masataka, Oono, Tatsuharu, Futamura, Yuki, Takagi, Seiko, Sato, Mitsuteru, Kuramoto, Kiyoshi, Watanabe, Makoto

المصدر: A&A 658, A158 (2022)

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics

الوصف: Context. Asteroids in comet-like orbits (ACOs) consist of asteroids and dormant comets. Due to their similar appearance, it is challenging to distinguish dormant comets from ACOs via general telescopic observations. Surveys for discriminating dormant comets from the ACO population have been conducted via spectroscopy or optical and mid-infrared photometry. However, they have not been conducted through polarimetry. Aims. We conducted the first polarimetric research of ACOs. Methods. We conducted a linear polarimetric pilot survey for three ACOs: (944) Hidalgo, (3552) Don Quixote, and (331471) 1984 QY1. These objects are unambiguously classified into ACOs in terms of their orbital elements (i.e., the Tisserand parameters with respect to Jupiter $T_\mathrm{J}$ significantly less than 3). Three ACOs were observed by the 1.6 m Pirka Telescope from UT 2016 May 25 to UT 2019 July 22 (13 nights). Results. We found that Don Quixote and Hidalgo have polarimetric properties similar to comet nuclei and D-type asteroids (optical analogs of comet nuclei). However, 1984 QY1 exhibited a polarimetric property consistent with S-type asteroids. We conducted a backward orbital integration to determine the origin of 1984 QY1, and found that this object was transported from the main belt into the current comet-like orbit via the 3:1 mean motion resonance with Jupiter. Conclusions. We conclude that the origins of ACOs can be more reliably identified by adding polarimetric data to the color and spectral information. This study would be valuable for investigating how the ice-bearing small bodies distribute in the inner Solar System.
Comment: 12 pages, 6 figures, accepted for publication in Astronomy and Astrophysics (A&A)

الوصول الحر: http://arxiv.org/abs/2111.00151Test

المؤلفون: Teh, Christopher, Wang, Chengsi, Watanabe, Makoto

المصدر: Teh , C , Wang , C & Watanabe , M 2024 , ' Strategic limitation of market accessibility : search platform design and welfare ' , Journal of Economic Theory , vol. 216 , 105798 . https://doi.org/10.1016/j.jet.2024.105798Test

مصطلحات موضوعية: Accessibility, Intermediation, Meeting technology, Platform, Search

الوصف: This paper explores the relationship between market accessibility and various participants' welfare in an intermediated directed-search market. For a general class of meeting technologies, we provide a necessary and sufficient condition under which efficiency requires imperfect accessibility, such that each seller's listing is only observed by some but not all buyers. We show that the platform optimally implements the efficient outcome, but fully extracts surplus from the transactions it intermediates. We also find that in general, buyers prefer to minimize market accessibility, while sellers prefer a weakly greater accessibility level than that which is socially efficient. The efficiency of imperfect accessibility is robust to the introduction of a second chance for unmatched buyers to search.

وصف الملف: application/pdf

الإتاحة: https://doi.org/10.1016/j.jet.2024.105798Test
https://research.monash.edu/en/publications/73aae87f-4808-4be5-8ae6-a764cde6cebcTest
https://researchmgt.monash.edu/ws/files/578681933/574238489_oa.pdfTest
http://www.scopus.com/inward/record.url?scp=85183996833&partnerID=8YFLogxKTest

المؤلفون: Sun, Liping, Jin, Yonghui, Nishio, Megumi, Watanabe, Makoto, Kamakura, Takeshi, Nagata, Sanae, Fukuda, Masayuki, Maekawa, Hirotsugu, Kawai, Shunsuke, Yamamoto, Takuya, Toguchida, Junya

المساهمون: 孫, 麗萍, 金, 永輝, 西尾, 恵, 渡辺, 真, 鎌倉, 武史, 永田, 早苗, 福田, 真幸, 前川, 裕継, 川井, 俊介, 山本, 拓也, 戸口田, 淳也, 90620344, 60546993

مصطلحات موضوعية: Cell Biology, Metabolism, Stem Cells

الوصف: 酸化的リン酸化の抑制がFOPの新たな治療法に繋がる可能性. 京都大学プレスリリース. 2024-03-11. ; Heterotopic ossification (HO) is a non-physiological bone formation where soft tissue progenitor cells differentiate into chondrogenic cells. In fibrodysplasia ossificans progressiva (FOP), a rare genetic disease characterized by progressive and systemic HO, the Activin A/mutated ACVR1/mTORC1 cascade induces HO in progenitors in muscle tissues. The relevant biological processes aberrantly regulated by activated mTORC1 remain unclear, however. RNA-sequencing analyses revealed the enrichment of genes involved in oxidative phosphorylation (OXPHOS) during Activin A–induced chondrogenesis of mesenchymal stem cells derived from FOP patient–specific induced pluripotent stem cells. Functional analyses showed a metabolic transition from glycolysis to OXPHOS during chondrogenesis, along with increased mitochondrial biogenesis. mTORC1 inhibition by rapamycin suppressed OXPHOS, whereas OXPHOS inhibitor IACS-010759 inhibited cartilage matrix formation in vitro, indicating that OXPHOS is principally involved in mTORC1-induced chondrogenesis. Furthermore, IACS-010759 inhibited the muscle injury–induced enrichment of fibro/adipogenic progenitor genes and HO in transgenic mice carrying the mutated human ACVR1. These data indicated that OXPHOS is a critical downstream mediator of mTORC1 signaling in chondrogenesis and therefore is a potential FOP therapeutic target.

العلاقة: https://www.cira.kyoto-u.ac.jp/j/pressrelease/news/240311-150000.htmlTest; https://www.infront.kyoto-u.ac.jp/post-4920Test/; http://hdl.handle.net/2433/287382Test; Life Science Alliance; e202302219

الإتاحة: http://hdl.handle.net/2433/287382Test

المؤلفون: Watanabe, Makoto, Atagi, Nobuhito, Makino, Yosuke, Kooguchi, Kunihiko, Ohta, Bon

المصدر: Acute Medicine & Surgery ; volume 11, issue 1 ; ISSN 2052-8817 2052-8817

الوصف: Background Marchiafava–Bignami disease is a rare neurological disease characterized by acquired lesions of the corpus callosum. Although the major causative etiology is chronic alcoholism, a case caused by acute alcohol intoxication has not yet been reported. Case Presentation A 19‐year‐old female with no known medical history or a history of chronic alcohol consumption was brought to the emergency department in a coma after binge alcohol consumption. Even after an overnight observation, she remained comatose. After a thorough examination including magnetic resonance imaging, which showed lesions of the corpus callosum, she was treated with thiamine for Marchiafava–Bignami disease. She recovered completely and at the follow‐up, the callosum lesion had resolved. Conclusion This is a rare case within the spectrum of Marchiafava–Bignami disease caused by acute consumption of alcohol. Clinicians should be aware of this potentially devastating critical condition among patients with severe alcohol intoxication, which might have been overlooked.

الإتاحة: https://doi.org/10.1002/ams2.960Test

المؤلفون: Kusano, Masahiro, Watanabe, Makoto

المساهمون: Japan Science and Technology Agency, JSPS KAKENHI

المصدر: Integrating Materials and Manufacturing Innovation ; ISSN 2193-9764 2193-9772

مصطلحات موضوعية: Industrial and Manufacturing Engineering, General Materials Science

الوصف: To understand the correlation between process, structures, and properties in laser powder bed fusion (L-PBF), it is essential to use numerical analysis as well as experimental approaches. A finite element thermal analysis uses a moving heat source model represented as a volumetric heat flux to simulate heat input by laser. Because of its computational efficiency, finite element thermal analysis is suitable for iterative procedures such as parametric study and process optimization. However, to obtain valid simulated results, the heat source model must be calibrated by comparison with experimental results for each laser scanning condition. The need for re-calibration limits the applicable window of laser scanning conditions in the thermal analysis. Thus, the current study developed a novel heat source model that is valid and precise under any laser scanning condition within a wide process window. As a secondary objective in the development, we quantitatively evaluated and compared the four heat source models proposed to date. It was found that the most suitable heat source model for the L-PBF is conical one among them. Then, a multiple linear regression analysis was performed to represent the heat source model as a function of laser power and scanning velocity. Consequently, the thermal analysis with the novel model is valid and precise within the wide process window of L-PBF.

الإتاحة: https://doi.org/10.1007/s40192-023-00334-2Test