1,749 research outputs found

    Proto-type installation of a double-station system for the optical-video-detection and orbital characterisation of a meteor/fireball in South Korea

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    We give a detailed description of the installation and operation of a double-station meteor detection system which formed part of a research & education project between Korea Astronomy Space Science Institute and Daejeon Science Highschool. A total of six light-sensitive CCD cameras were installed with three cameras at SOAO and three cameras at BOAO observatory. A double-station observation of a meteor event enables the determination of the three-dimensional orbit in space. This project was initiated in response to the Jinju fireball event in March 2014. The cameras were installed in October/November 2014. The two stations are identical in hardware as well as software. Each station employes sensitive Watec-902H2 cameras in combination with relatively fast f/1.2 lenses. Various fields of views were used for measuring differences in detection rates of meteor events. We employed the SonotaCo UFO software suite for meteor detection and their subsequent analysis. The system setup as well as installation/operation experience is described and first results are presented. We also give a brief overview of historic as well as recent meteor (fall) detections in South Korea. For more information please consult http://meteor.kasi.re.kr .Comment: Technical/instrumentation description of a professional meteor detection system, 23 pages, 20 figures (color/monochrome), 5 tables, submitted to the Journal of Korean Astronomical Society (JKAS, http://jkas.kas.org/, http://jkas.kas.org/history.html

    Bocavirus Infection in Hospitalized Children, South Korea

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    This study presents the first evidence of human bocavirus infection in South Korean children. The virus was detected in 27 (8.0%) of 336 tested specimens, including 17 (7.5%) of 225 virus-negative specimens, collected from children with acute lower respiratory tract infection

    Measurement of Planetary Boundary Layer Winds with Scanning Doppler Lidar

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    The accurate measurement of wind profiles in the planetary boundary layer (PBL) is important not only for numerical weather prediction, but also for air quality modeling. Two wind retrieval methods using scanning Doppler light detection and ranging (lidar) measurements were compared and validated with simultaneous radiosonde soundings. A comparison with 17 radiosonde sounding profiles showed that the sine-fitting method was able to retrieve a larger number of data points, but the singular value decomposition method showed significantly smaller bias (0.57 m s(-1)) and root-mean-square error (1.75 m s(-1)) with radiosonde soundings. Increasing the averaging time interval of radial velocity for obtaining velocity azimuth display scans to 15 min resulted in better agreement with radiosonde soundings due to the signal averaging effect on noise. Simultaneous measurements from collocated wind Doppler lidar and aerosol Mie-scattering lidar revealed the temporal evolution of PBL winds and the vertical distribution of aerosols within the PBL

    Immunohistochemical Study of So-called Sclerosing Hemangioma of the Lung

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    The origin of tumor cells composing sclerosing hemangioma of the lung has been extensively studied by many researchers, but it is still obscure. We analyzed seven cases of sclerosing hemangioma of the lung from the files of Seoul National University Hospital, Department of Pathology by immunohistochemical staining as well as histologic observation. The tumors are composed of two kinds of cells; the epithelial cells lining the papillary area are cytokeratin( +) and vimentinl -), while subepithelial tumor cells are cytokeratin( -) and vimentinl +). Two kinds of cells are separated by basement membrane, visualized by type IV collagen monoclonal antibody. The angiomatous and solid areas are devoid of cytokeratin( +) epithelial cells and basement membrane is not formed beneath the blood-filled cysts. The epitheial cells are frequently seen at the periphery of the tumor, where the epithelial cells maintain their pseudostratified and ciliated character of bronchiolar lining epithelium. The above findings suggest that the epithelial cells would not be tumor cells but an entrapped mucosa, and that the tumor cells be not of epithelial origin

    Pole-skipping points in 2D gravity and SYK model

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    We represent the first investigation of pole-skipping on both the gravity and field theory sides. In contrast to the higher dimensional models, there is no momentum degree of freedom in (1+1)(1+1)-dimensional bulk theory. Thus, we then consider a scalar field mass as our degree of freedom for the pole-skipping phenomenon instead of momentum. The pole-skipping frequencies of the scalar field in 2D gravity are the same as higher dimensional cases: ω=i2πTn\omega=-i2\pi Tn for positive integer nn. At each of these frequencies, there is a corresponding pole-skipping mass, so the pole-skipping points exist in the (ω,m)(\omega,m) space. We also compute the pole-skipping points of the SYK model in (ω,h)(\omega, h) space where hh is the dimension of the bilinear primary operator. We find that there is a one-to-one correspondence of the pole-skipping points between the JT gravity and the SYK model. To obtain the pole-skipping points, we need to consider the parameter ϵ\epsilon related to chemical potential on the horizon of charged JT gravity and the particle-hole asymmetric parameter E\mathcal{E} of the complex SYK model as shift parameters. This highlights the ϵE\epsilon-\mathcal{E} correspondence in relation to pole-skipping
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