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Search Results: 1 - 10 of 1709 matches for " Jungmi Kwon "
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YSO search toward the boundary of the Central Molecular Zone with near-infrared polarimetry
Tatsuhito Yoshikawa,Shogo Nishiyama,Motohide Tamura,Jungmi Kwon,Tetsuya Nagata
Physics , 2014, DOI: 10.1088/0067-0049/213/2/22
Abstract: We have carried out near-infrared polarimetry toward the boundary of the Central Molecular Zone, in the field of (-1.4 deg $\lesssim l \lesssim$ -0.3 deg and 1.0 deg $\lesssim l \lesssim$ 2.9 deg, $|b|\lesssim$ 0.1 deg), using the near-infrared polarimetric camera SIRPOL on the 1.4 m Infrared Survey Facility telescope. We have selected 112 intrinsically polarized sources on the basis of the estimate of interstellar polarization on Stokes $Q/I-U/I$ planes. The selected sources are brighter than $K_S=14.5$ mag and have polarimetric uncertainty $\delta P<1\,%$. Ten of these distinctive polarized sources are fit well with spectral energy distributions of young stellar objects when using the photometry in the archive of the Spitzer Space Telescope mid-infrared data. However, many sources have spectral energy distributions of normal stars suffering heavy interstellar extinction; these might be stars behind dark clouds. Due to the small number of distinctive polarized sources and candidates of young stellar object, we cannot judge if there is a decline of them outside the Central Molecular Zone. Many of massive candidates of young stellar object in the literature have only small intrinsic polarization. This might suggest that their masses are 4-15 M$_{{\rm sun}}$, whose intrinsic polarization has been expected to be small.
Electroacupuncture for Decorticate Rigidity of the Upper Limbs in a Patient with Anoxic Brain Damage
WooSang Jung,SeungWon Kwon,SeongUk Park,SangKwan Moon,JungMi Park,ChangNam Ko,KiHo Cho
Case Reports in Medicine , 2013, DOI: 10.1155/2013/524603
Abstract: Decorticate rigidity is a type of abnormal posturing that can make it difficult to move a patient and to change the patient’s position to prevent a decubitus ulcer. This condition poses a latent risk of bed sores. To prevent those complications, we used electroacupuncutre for decorticate rigidity of the upper limbs in a patient with anoxic brain damage. A 51-year-old man complained of rigidity of both of the upper and lower extremities due to anoxic brain damage. His rigidity was exhibited as flexed arms and extended legs, which are the typical positions in decorticate rigidity. Prior to electroacupuncture, his decorticate rigidity was treated with dantrolene sodium and baclofen. However, his rigidity had not improved. This patient received total 41 sessions of electroacupuncture. The patient’s Modified Ashworth’s Scale changed from 4 at baseline to 2 after the treatment, indicating an improvement in the rigidity of the upper limbs. Preston’s Hypertonicity Scale and passive ROM of the elbow joints also improved. We report the observed effects of electroacupuncture for decorticate rigidity of the upper limbs in a patient with anoxic brain damage. Further controlled studies are needed to determine whether electroacupuncture is a useful alternative treatment for decorticate rigidity in patients with anoxic brain damage. 1. Introduction We report a case of decorticated rigidity due to anoxic brain damage that was successfully treated with electro-acupuncture combined with conventional therapeutic options such as muscle relaxants and physical manual therapy. 2. Case History 2.1. Patient Characteristics and Diagnosis A 51-year-old man complaining of rigidity of both of the upper and lower extremities due to anoxic brain damage was admitted to the Department of Cardiovascular and Neurological Diseases of Kyung Hee University Oriental Medicine Hospital. This patient had collapsed during a marathon and had received cardiopulmonary resuscitation (CPR). The doctors recognized acute myocardial infarction (MI) and provided conventional therapies for this condition. However, anoxic brain damage was caused by insufficient blood supply to the brain. He manifested rigidity, dyspnea, and dysphagia. His rigidity was exhibited as flexed arms and extended legs, which are the typical positions in decorticate rigidity. Although this patient had underlying hypertension and diabetes mellitus, he and his family had not recognized these conditions until onset of MI. At admission, he revealed GCS score 7 (E4 V0 M3) and used tracheostomy tube, nasogastric tube. The brain computed
Magnetic Field Structure of the HH 1-2 Region: Near-Infrared Polarimetry of Point-Like Sources
Jungmi Kwon,Minho Choi,Soojong Pak,Ryo Kandori,Motohide Tamura,Tetsuya Nagata,Shuji Sato
Physics , 2009, DOI: 10.1088/0004-637X/708/1/758
Abstract: The HH 1-2 region in the L1641 molecular cloud was observed in the near-IR J, H, and Ks bands, and imaging polarimetry was performed. Seventy six point-like sources were detected in all three bands. The near-IR polarizations of these sources seem to be caused mostly by the dichroic extinction. Using a color-color diagram, reddened sources with little infrared excess were selected to trace the magnetic field structure of the molecular cloud. The mean polarization position angle of these sources is about 111 deg, which is interpreted as the projected direction of the magnetic field in the observed region of the cloud. The distribution of the polarization angle has a dispersion of about 11 deg, which is smaller than what was measured in previous studies. This small dispersion gives a rough estimate of the strength of the magnetic field to be about 130 microG and suggests that the global magnetic field in this region is quite regular and straight. In contrast, the outflows driven by young stellar objects in this region seem to have no preferred orientation. This discrepancy suggests that the magnetic field in the L1641 molecular cloud does not dictate the orientation of the protostars forming inside.
Near Infrared Circular Polarization Images of NGC 6334-V
Jungmi Kwon,M. Tamura,P. Lucas,Jun Hashimoto,Nobuhiko Kusakabe,Ryo Kandori,Yasushi Nakajima,Takahiro Nagayama,Tetsuya Nagata,James Hough
Physics , 2013, DOI: 10.1088/2041-8205/765/1/L6
Abstract: We present results from deep imaging linear and circular polarimetry of the massive star-forming region NGC 6334- V. These observations show high degrees of circular polarization (CP), as much as 22 % in the Ks band, in the infrared nebula associated with the outflow. The CP has an asymmetric positive/negative pattern and is very extended (~80" or 0.65 pc). Both the high CP and its extended size are larger than those seen in the Orion CP region. Three-dimensional Monte Carlo light-scattering models are used to show that the high CP may be produced by scattering from the infrared nebula followed by dichroic extinction by an optically thick foreground cloud containing aligned dust grains. Our results show not only the magnetic field orientation of around young stellar objects but also the structure of circumstellar matter such as outflow regions and their parent molecular cloud along the line of sight. The detection of the large and extended CP in this source and the Orion nebula may imply the CP origin of the biological homochirality on Earth.
Near-Infrared Circular Polarization Survey in Star-Forming Regions: Correlations and Trends
Jungmi Kwon,Motohide Tamura,James H. Hough,Nobuhiko Kusakabe,Tetsuya Nagata,Yasushi Nakajima,Phil W. Lucas,Takahiro Nagayama,Ryo Kandori
Physics , 2014, DOI: 10.1088/2041-8205/795/1/L16
Abstract: We have conducted a systematic near-infrared circular polarization (CP) survey in star-forming regions, covering high-mass, intermediate-mass, and low-mass young stellar objects. All the observations were made using the SIRPOL imaging polarimeter on the Infrared Survey Facility 1.4 m telescope at the South African Astronomical Observatory. We present the polarization properties of ten sub-regions in six star-forming regions. The polarization patterns, extents, and maximum degrees of linear and circular polarizations are used to determine the prevalence and origin of CP in the star-forming regions. Our results show that the CP pattern is quadrupolar in general, the CP regions are extensive, up to 0.65 pc, the CP degrees are high, up to 20 %, and the CP degrees decrease systematically from high- to low-mass young stellar objects. The results are consistent with dichroic extinction mechanisms generating the high degrees of CP in star forming regions.
Near-IR Imaging Polarimetry toward a Bright-Rimmed Cloud: Magnetic Field in SFO 74
Takayoshi Kusune,Koji Sugitani,Jingqi Miao,Motohide Tamura,Yaeko Sato,Jungmi Kwon,Makoto Watanabe,Shogo Nishiyama,Takahiro Nagayama,Shuji Sato
Physics , 2014, DOI: 10.1088/0004-637X/798/1/60
Abstract: We have made near-infrared (JHKs) imaging polarimetry of a bright-rimmed cloud (SFO 74). The polarization vector maps clearly show that the magnetic field in the layer just behind the bright rim is running along the rim, quite different from its ambient magnetic field. The direction of the magnetic field just behind the tip rim is almost perpendicular to that of the incident UV radiation, and the magnetic field configuration appears to be symmetric as a whole with respect to the cloud symmetry axis. We estimated the column and number densities in the two regions (just inside and far inside the tip rim), and then derived the magnetic field strength, applying the Chandrasekhar-Fermi method. The estimated magnetic field strength just inside the tip rim, ~90 uG, is stronger than that far inside, ~30 uG. This suggests that the magnetic field strength just inside the tip rim is enhanced by the UV radiation induced shock. The shock increases the density within the top layer around the tip, and thus increases the strength of the magnetic field. The magnetic pressure seems to be comparable to the turbulent one just inside the tip rim, implying a significant contribution of the magnetic field to the total internal pressure. The mass-to-flux ratio was estimated to be close to the critical value just inside the tip rim. We speculate that the flat-topped bright rim of SFO 74 could be formed by the magnetic field effect.
Complex Scattered Radiation Fields and Multiple Magnetic Fields in the Protostellar Cluster in NGC 2264
Jungmi Kwon,Motohide Tamura,Ryo Kandori,Nobuhiko Kusakabe,Jun Hashimoto,Yasushi Nakajima,Fumitaka Nakamura,Takahiro Nagayama,Tetsuya Nagata,James H. Hough,Michael W. Werner,Paula S. Teixeira
Physics , 2011, DOI: 10.1088/0004-637X/741/1/35
Abstract: Near-infrared (IR) imaging polarimetry in the J, H, and Ks bands has been carried out for the protostellar cluster region around NGC 2264 IRS 2 in the Monoceros OB1 molecular cloud. Various infrared reflection nebulae clusters (IRNCs) associated with NGC 2264 IRS 2 and IRAS 12 S1 core were detected as well as local infrared reflection nebulae (IRNe). The illuminating sources of the IRNe were identified with known or new near- and mid-IR sources. In addition, 314 point-like sources were detected in all three bands and their aperture polarimetry was studied. Using a color-color diagram, reddened field stars and diskless pre-main sequence stars were selected to trace the magnetic field (MF) structure of the molecular cloud. The mean polarization position angle of the point-like sources is 81 \pm 29 degree in the cluster core, and 58 \pm 24 degree in the perimeter of the cluster core, which is interpreted as the projected direction on the sky of the MF in the observed region of the cloud. The Chandrasekhar-Fermi method gives a rough estimate of the MF strength to be about 100 {\mu}G. A comparison with recent numerical simulations of the cluster formation implies that the cloud dynamics is controlled by the relatively strong MF. The local MF direction is well associated with that of CO outflow for IRAS 12 S1 and consistent with that inferred from submillimeter polarimetry. In contrast, the local MF direction runs roughly perpendicular to the Galactic MF direction.
Magnetically Confined Interstellar Hot Plasma in the Nuclear Bulge of our Galaxy
Shogo Nishiyama,Kazuki Yasui,Tetsuya Nagata,Tatsuhito Yoshikawa,Hideki Uchiyama,Rainer Sch?del,Hirofumi Hatano,Shuji Sato,Koji Sugitani,Takuya Suenaga,Jungmi Kwon,Motohide Tamura
Physics , 2013, DOI: 10.1088/2041-8205/769/2/L28
Abstract: The origin of the Galactic center diffuse X-ray emission (GCDX) is still under intense investigation. In particular, the interpretation of the hot (kT ~ 7 keV) component of the GCDX, characterised by the strong Fe 6.7 keV line emission, has been contentious. If the hot component originates from a truly diffuse interstellar plasma, not a collection of unresolved point sources, such plasma cannot be gravitationally bound, and its regeneration would require a huge amount of energy. Here we show that the spatial distribution of the GCDX does NOT correlate with the number density distribution of an old stellar population traced by near-infrared light, strongly suggesting a significant contribution of the diffuse interstellar plasma. Contributions of the old stellar population to the GCDX are implied to be about 50 % and 20 % in the Nuclear stellar disk and Nuclear star cluster, respectively. For the Nuclear stellar disk, a scale height of 0.32 +- 0.02 deg is obtained for the first time from the stellar number density profiles. We also show the results of the extended near-infrared polarimetric observations in the central 3 deg * 2 deg region of our Galaxy, and confirm that the GCDX region is permeated by a large scale, toroidal magnetic field as previously claimed. Together with observed magnetic field strengths close to energy equipartition, the hot plasma could be magnetically confined, reducing the amount of energy required to sustain it.
Near-IR Polarimetry Around 30 Doradus: I. Separation of the Galactic Sources
Kim Jaeyeong,Pak Soojong,Choi Minho,Kang Wonseok,Kandori Ryo,Tamura Motohide,Nagata Tetsuya,Kwon Jungmi,Kato Daisuke,Daniel T Jaffe
Physics , 2011,
Abstract: A 20 arcmin \times 20 arcmin region around 30 Doradus in the Large Magellanic Cloud (LMC) is observed and analyzed in the near-infrared. We obtain polarimetry data in the J, H, and K_s bands using the SIRIUS polarimeter SIRPOL at the Infrared Survey Facility 1.4 m telescope. We measure the Stokes parameters of 2562 point-like sources to derive the degree of polarization and the polarization position angles. We discuss the statistics of the groups classified by color-magnitude diagram and proper motions of the sources, in order to separate the Galactic foreground sources from those present in the LMC. We notice that groups classified by the proper motion data show a tendency towards different polarimetric properties.
Number Density Distribution of Near-Infrared Sources on a Sub-Degree Scale in the Galactic Center: Comparison with the Fe XXV Ka Line at 6.7 keV
Kazuki Yasui,Shogo Nishiyama,Tatsuhito Yoshikawa,Schun Nagatomo,Hideki Uchiyama,Takeshi G. Tsuru,Katsuji Koyama,Motohide Tamura,Jungmi Kwon,Koji Sugitani,Rainer Sch?del,Tetsuya Nagata
Physics , 2015, DOI: 10.1093/pasj/psv100
Abstract: The stellar distribution derived from an $H$ and $K_{\mathrm S}$-band survey of the central region of our Galaxy is compared with the Fe XXV K$\alpha$ (6.7 keV) line intensity observed with the Suzaku satellite. The survey is for the Galactic coordinates $|l| \lesssim 3^{\circ}.0$ and $|b| \lesssim 1^{\circ}.0$ (equivalent to 0.8 kpc $\times$ 0.3 kpc for $R_0 = 8$ kpc), and the number-density distribution $N(K_{\mathrm S,0}; l, b)$ of stars is derived using the extinction-corrected magnitude $K_{\mathrm S,0}=10.5$. This is deep enough to probe the old red giant population and in turn to estimate the ($l$, $b$) distribution of faint X-ray point sources such as coronally active binaries and cataclysmic variables. In the Galactic plane ($b=0^{\circ}$), $N(10.5; l, b)$ increases to the Galactic center as $|l|^{-0.30 \pm 0.03}$ in the range of $-0^{\circ}.1 \geq l \geq -0^{\circ}.7$, but this increase is significantly slower than the increase ($|l|^{-0.44 \pm 0.02}$ ) of the Fe XXV K$\alpha$ line intensity. If normalized with the ratios in the outer region $1^{\circ}.5 \leq |l| \leq 2^{\circ}.8$, where faint X-ray point sources are argued to dominate the diffuse Galactic X-ray ridge emission, the excess of the Fe XXV K$\alpha$ line intensity over the stellar number density is at least a factor of two at $|l| = 0^{\circ}.1$. This indicates that a significant part of the Galactic center diffuse emission arises from a truly diffuse optically-thin thermal plasma, and not from an unresolved collection of faint X-ray point sources related to the old stellar population.
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