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Where is a Marginally Stable Orbit in Luminous Accretion Disk
Ken-ya Watarai,Shin Mineshige 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.3
Impressed by a widespread misunderstanding of the issue, we return to the old question concerning the location of the inner edge of the accretion disk around a black hole. That is, \the inner edge does not coincide with the location of the inner most stable Keplerian circular orbit." We show that the ow does not have a potential minimum for accretion rates _ > 10LE=c2, with LE being the Eddington luminosity and c being the speed of light. This property is realized even for relatively small viscosity parameters (i.e., 0:01) because of the eect of the pressure gradient. In conclusion, an argument based on the last circular orbit of a test particle cannot give a correct inner boundary for the super-critical ow, and the inner edge should be determined in connection with radiation eciency.
Observational Properties of Supercritical Accretion Flows
Ken-ya Watarai 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4
I would like to review the observational properties of supercritical accretion °ows as an origin of high luminosity sources, e.g., galactic microquasars, ultraluminous X-ray sources near galaxies, or narrow line Seyfert 1 galaxies. Models of supercritical accretion °ows have been investigated by many authors; however, the observational properties have not been su±ciently studied. In particular, the geometrical thickness of the °ow strongly aects the observational spectrum because, when the viewing angle in the disk is high, the outer disk blocks emission from the disk inner region; i.e., the self-occultation eect will be important. Even if I take into account the eect of general relativity (light bending, Doppler boosting), the geometrical eect of the supercritical accretion °ows signi.cantly changes the spectrum for high viewing angles: spectrum softening occurs due to the self-occultation eect. In addition, several observational implications and applications of supercritical accretion °ows are presented in this paper.
Fitting of Light Curves for Microquasar V4641 Sgr
Shinji Nishiyama,Jun Fukue,Akira Arai,Kenya Watarai 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4
We report the .tting results of theoretical light curves for microquasar V4641 Sgr. In this study, we apply a new accretion disk model that is presented by Fukue to observed R-band light curves of V4641 Sgr. The new model takes into account the geometrical thickness of the disk, so it may be able to describe the two deep minima of the observed light curves. The best-.t parameters show that the system has a relatively high inclination angle, i = 75±, and that the mass accretion rate is around the Eddington rate. We propose the importance of the geometry of the accretion disk to explain the deep minima observed in this object.
Miori Kishimoto,Sa-Hun Pae,Naoyoshi Muroya,Hirokazu Watarai,Hiroshi Anzai,이기자,Junichiro Shimizu,Motoki Sasaki,Kazutaka Yamada 대한수의학회 2010 Journal of Veterinary Science Vol.11 No.1
Caudolateral curvilinear osteophyte (CCO), an osteophyte at the site of joint capsule attachment on the caudal aspect of the femoral neck, has been advocated as a radiographic criterion for coxofemoral subluxation. The correlation between the presence of CCO on radiographs (radiographic- CCO), the size of the CCO (CCO index) on three-dimensional computed tomographic (CT) images, and hip evaluation using transverse CT images was assessed in 22 Border Collies. CCOs were detected on the radiographs and CT images of 32% and 100% femurs, respectively. The CCO index correlated significantly with radiographic-CCO, but a large CCO index did not necessarily imply that the CCO was visible on radiographs. Hence, radiographic-CCO findings should be used cautiously in hip evaluation of Border Collies.
Lee, Jin Ju,Kim, Dong Hyeok,Kim, Dae Geun,Lee, Hu Jang,Min, Wongi,Rhee, Man Hee,Cho, Jae Youl,Watarai, Masahisa,Kim, Suk American Society for Microbiology 2013 Infection and immunity Vol.81 No.7
<P><I>Brucella abortus</I> is an intracellular pathogen that uses a crafty strategy to invade and proliferate within host cells, but the distinct signaling pathways associated with phagocytic mechanisms of <I>B. abortus</I> remain unclear. The present study was performed to test the hypothesis that Toll-like receptor 4 (TLR4)-linked signaling interacting with Janus kinase 2 (JAK2) plays an essential role in <I>B. abortus</I> phagocytosis by macrophages. The effects of TLR4-JAK2 signaling on <I>B. abortus</I> phagocytosis in murine macrophage RAW 264.7 cells were observed through an infection assay and confocal microscopy. We determined that the uptake of <I>B. abortus</I> was negatively affected by the dysfunction of TLR4 and JAK2. F-actin polymerization detected by flow cytometry and F-actin assay was amplified for <I>B. abortus</I> entry, whereas that event was attenuated by the disruption of TLR4 and JAK2. Importantly, JAK2 phosphorylation and actin skeleton reorganization were suppressed immediately after <I>B. abortus</I> infection in bone marrow-derived macrophages (BMDMs) from TLR4<SUP>−/−</SUP> mice, showing the cooperation of JAK2 with TLR4. Furthermore, small GTPase Cdc42 participated in the intermediate pathway of TLR4-JAK2 signaling on <I>B. abortus</I> phagocytosis. Consequently, TLR4-associated JAK2 activation in the early cellular signaling events plays a pivotal role in <I>B. abortus</I>-induced phagocytic processes in macrophages, implying the pathogenic significance of JAK2-mediated entry. Here, we elucidate that this specific phagocytic mechanism of <I>B. abortus</I> might provide achievable strategies for inhibiting <I>B. abortus</I> invasion.</P>
Kim, Dong Hyeok,Lim, Jeong Ju,Lee, Jin Ju,Kim, Dae Geun,Lee, Hu Jang,Min, Wongi,Kim, Kwang Dong,Chang, Hong Hee,Rhee, Man Hee,Watarai, Masahisa,Kim, Suk Elsevier 2012 Veterinary microbiology Vol.158 No.3
<P><B>Abstract</B></P><P><I>Brucella abortus</I>, the causative agent of brucellosis, can survive and replicate within host cells. Understanding bacterial virulence factors and bacteria–host cell interactions is critical for controlling brucellosis, yet very little is known about the virulence strategies and signaling pathways activated in phagocytes during infection to ensure their growth and survival. <I>B. abortus</I> was mutagenized by mini-Tn5Km2 transposon mutagenesis to identify virulence genes related to the internalization and intracellular replication of the bacteria. Of the total 2300 mutants used to infect HeLa cells, 23 mutants defective for intercellular growth and the mutated genes were identified. Sequence analysis of DNA flanking the transposon showed various insertion sites in bacterial genes that might be associated with virulence, including genes associated with lipoproteins, amino acid metabolism, translation, transcription, carbohydrate transport, coenzyme transport, inorganic ion transport, energy metabolism, membrane transport, and cell wall/membrane biogenesis. Moreover, mutants were classified into class I, class II and class III as higher, similar, and lower internalization, respectively, into HeLa cells. Furthermore, defective mutants for intracellular growth in HeLa cells were found to be defective in RAW 264.7 cells. Taken together, we suggest that the identified virulence associated genes might contribute to the intracellular growth and survival of <I>B. abortus</I> in phagocytes.</P>
An Optical Source Catalog of the North Ecliptic Pole Region
Hwang, Narae,Lee, Myung Gyoon,Lee, Hyung Mok,Im, Myungshin,Kim, Taehyun,Matsuhara, Hideo,Wada, Takehiko,Oyabu, Shinki,Pak, Soojong,Chun, Moo‐,Young,Watarai, Hidenori,Nakagawa, Takao,Pearson, Chr IOP Publishing 2007 The Astrophysical journal Supplement series Vol.172 No.2
Lee, Jin Ju,Kim, Dae Geun,Kim, Dong Hyeok,Simborio, Hannah Leah,Min, Wongi,Lee, Hu Jang,Her, Moon,Jung, Suk Chan,Watarai, Masahisa,Kim, Suk American Society for Biochemistry and Molecular Bi 2013 The Journal of biological chemistry Vol.288 No.39
<P>Lipid raft-associated clathrin is essential for host-pathogen interactions during infection. <I>Brucella abortus</I> is an intracellular pathogen that circumvents host defenses, but little is known about the precise infection mechanisms that involve interaction with lipid raft-associated mediators. The aim of this study was to elucidate the clathrin-mediated phagocytic mechanisms of <I>B. abortus</I>. The clathrin dependence of <I>B. abortus</I> infection in HeLa cells was investigated using an infection assay and immunofluorescence microscopy. The redistribution of clathrin in the membrane and in phagosomes was investigated using sucrose gradient fractionation of lipid rafts and the isolation of <I>B. abortus</I>-containing vacuoles, respectively. Clathrin and dynamin were concentrated into lipid rafts during <I>B. abortus</I> infection, and the entry and intracellular survival of <I>B. abortus</I> within HeLa cells were abrogated by clathrin inhibition. Clathrin disruption decreased actin polymerization and the colocalization of <I>B. abortus</I>-containing vacuoles with clathrin and Rab5 but not lysosome-associated membrane protein 1 (LAMP-1). Thus, our data demonstrate that clathrin plays a fundamental role in the entry and intracellular survival of <I>B. abortus</I> via interaction with lipid rafts and actin rearrangement. This process facilitates the early intracellular trafficking of <I>B. abortus</I> to safe replicative vacuoles.</P>