79 research outputs found

    フラクタル フゴウ オ モチイタ ガゾウ パターン ケンサク ノ イチシュホウ

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    画像のフラクタル符号化の過程で定まるアフィン写像について,その逆写像の族を反復計算する力学系を考えると,その状態空間中のアトラクタの引力圏(収束領域)を求めることにより,画像の領域分割が可能である.本論文は,この手法を応用し,指定した検索パターンを画像内から抽出する方法を提案する.また,精度の高い結果を得るための補正方法,検索結果画像の抽出について述べる.すべての処理は圧縮データを直接用い,原画像の情報は用いない.応用例として,人型の検索パターンを指定し,画像内から人間領域を抽出した

    Spitzer Survey of the Large Magellanic Cloud, Surveying the Agents of a Galaxy's Evolution (SAGE) I: Overview and Initial Results

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    We are performing a uniform and unbiased, ~7x7 degrees imaging survey of the Large Magellanic Cloud (LMC), using the IRAC and MIPS instruments on board the Spitzer Space Telescope in order to survey the agents of a galaxy's evolution (SAGE), the interstellar medium (ISM) and stars in the LMC. The detection of diffuse ISM with column densities >1.2x10^21 H cm^-2 permits detailed studies of dust processes in the ISM. SAGE's point source sensitivity enables a complete census of newly formed stars with masses >3 solar masses that will determine the current star formation rate in the LMC. SAGE's detection of evolved stars with mass loss rates >1x10^-8 solar masses per year will quantify the rate at which evolved stars inject mass into the ISM of the LMC. The observing strategy includes two epochs in 2005, separated by three months, that both mitigate instrumental artifacts and constrain source variability. The SAGE data are non-proprietary. The data processing includes IRAC and MIPS pipelines and a database for mining the point source catalogs, which will be released to the community in support of Spitzer proposal cycles 4 and 5. We present initial results on the epoch 1 data with a special focus on the N79 and N83 region. The SAGE epoch 1 point source catalog has ~4 million sources. The point source counts are highest for the IRAC 3.6 microns band and decrease dramatically towards longer wavelengths consistent with the fact that stars dominate the point source catalogs and that the dusty objects, e.g. young stellar objects and dusty evolved stars that detected at the longer wavelengths, are rare in comparison. We outline a strategy for identifying foreground MW stars, that may comprise as much as 18% of the source list, and background galaxies, that may comprise ~12% of the source list.Comment: Accepted by the Astronomical Journa

    Spitzer survey of the Large Magellanic Cloud, surveying the agents of a galaxy's evolution (SAGE). IV. Dust properties in the interstellar medium

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    The goal of this paper is to present the results of a preliminary analysis of the extended infrared (IR) emission by dust in the interstellar medium (ISM) of the Large Magellanic Cloud (LMC). We combine Spitzer Surveying the Agents of Galaxy Evolution (SAGE) and Infrared Astronomical Satellite (IRAS) data and correlate the infrared emission with gas tracers of H I, CO, and Hα. We present a global analysis of the infrared emission as well as detailed modeling of the spectral energy distribution (SED) of a few selected regions. Extended emission by dust associated with the neutral, molecular, and diffuse ionized phases of the ISM is detected at all IR bands from 3.6 μm to 160 μm. The relative abundance of the various dust species appears quite similar to that in the Milky Way (MW) in all the regions we have modeled. We construct maps of the temperature of large dust grains. The temperature map shows variations in the range 12.1-34.7 K, with a systematic gradient from the inner to outer regions, tracing the general distribution of massive stars and individual H II regions as well as showing warmer dust in the stellar bar. This map is used to derive the far-infrared (FIR) optical depth of large dust grains. We find two main departures in the LMC with respect to expectations based on the MW: (1) excess mid-infrared (MIR) emission near 70 μm, referred to as the 70 μm excess, and (2) departures from linear correlation between the FIR optical depth and the gas column density, which we refer to as FIR excess emission. The 70 μm excess increases gradually from the MW to the LMC to the Small Magellanic Cloud (SMC), suggesting evolution with decreasing metallicity. The excess is associated with the neutral and diffuse ionized gas, with the strongest excess region located in a loop structure next to 30 Dor. We show that the 70 μm excess can be explained by a modification of the size distribution of very small grains with respect to that in the MW, and a corresponding mass increase of ≃13% of the total dust mass in selected regions. The most likely explanation is that the 70 μm excess is due to the production of large very small grains (VSG) through erosion of larger grains in the diffuse medium. This FIR excess could be due to intrinsic variations of the dust/gas ratio, which would then vary from 4.6 to 2.3 times lower than the MW values across the LMC, but X_(CO) values derived from the IR emission would then be about three times lower than those derived from the Virial analysis of the CO data. We also investigate the possibility that the FIR excess is associated with an additional gas component undetected in the available gas tracers. Assuming a constant dust abundance in all ISM phases, the additional gas component would have twice the known H I mass. We show that it is plausible that the FIR excess is due to cold atomic gas that is optically thick in the 21 cm line, while the contribution by a pure H_2 phase with no CO emission remains a possible explanation

    Intracellular expression of toll-like receptor 4 in neuroblastoma cells and their unresponsiveness to lipopolysaccharide

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    BACKGROUND: Recently it has been reported that, toll-like receptors (TLRs) are expressed on a series of tumor cells, such as colon cancer, breast cancer, prostate cancer, melanoma and lung cancer. Although some cancer cells like melanoma cells are known to respond to lipopolysaccharide (LPS) via TLR4, not all cancer cells are positive for TLR4. There is little information on the expression and function of TLR4 in neuroblastoma cells. In this study, we investigated the expression of TLR4 in human neuroblastoma NB-1 cell line. METHODS: Expression and localization of TLR4 were detected by reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometric analysis, respectively. Activation of nuclear factor (NF)-κB by LPS was detected by degradation of IκB-α and NF-κB luciferase assay. Activation and expression of mitogen-activated protein (MAP) kinase and interferon regulatory factor (IRF)-3 was detected by immunoblot analysis. RESULTS: Human NB-1 neuroblastoma cells expressed intracellular form of TLR4, but not the cell surface form. Further, NB-1 cells express CD14, MD2 and MyD88, which are required for LPS response. However, LPS did not significantly induce NF-κB activation in NB-1 cells although it slightly degraded IκB-α. NB-1 cells expressed no IRF-3, which plays a pivotal role on the MyD88-independent pathway of LPS signaling. Collectively, NB-1 cells are capable to avoid their response to LPS. CONCLUSION: Although human NB-1 neuroblastoma cells possessed all the molecules required for LPS response, they did not respond to LPS. It might be responsible for intracellular expression of TLR4 or lack of IRF-3

    シシツ テイカ リョウホウ ニヨル ケイドウミャク プラーク アンテイカ ノ ヒョウカ : チョウオンパ integrated backscatter オ モチイタ カラー マッピング システム ノ カイハツ ト リンショウ オウヨウ

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    Background : The carotid plaque vulnerability is related to myocardial and cerebral infarction. We intended to develop an imaging system which enables to visualize tissue characteristics in the carotid plaques based on ultrasound integrated backscatter(IB). And to test its clinical efficacy, effect of the statin therapy on the plaques was evaluated with our software. Methods and Results : Carotid ultrasound examination was performed and ultrasonographic RAW data of the plaques were obtained from8patients undergoing carotid artery endarterectomy. Tissue characteristics in the plaques of resected examples were compared with preoperative ultrasonic images and the tissue IB values corresponding to the specimens were determined for developing our imaging system. Using this system, Color-coded maps of plaques in the three patients were constructed before and after lipid lowing therapy. We could demonstrate that lipid fraction in each plaque decreased and fibrous or calcification fraction increased in the follow-up study. Conclusions : Changes in histology of carotid plaques by statin could visualized with our imaging system. This technique may become a useful tool for the management of atherosclerosis

    分子動力学法を用いたフッ化炭素繊維材料における赤外応答の研究

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    京都大学0048新制・課程博士博士(理学)甲第16644号理博第3756号新制||理||1544(附属図書館)29319京都大学大学院理学研究科化学専攻(主査)教授 谷村 吉隆, 准教授 安藤 耕司, 教授 鈴木 俊法学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA

    分子動力学法を用いたフッ化炭素繊維材料における赤外応答の研究

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    京都大学0048新制・課程博士博士(理学)甲第16644号理博第3756号新制||理||1544(附属図書館)29319京都大学大学院理学研究科化学専攻(主査)教授 谷村 吉隆, 准教授 安藤 耕司, 教授 鈴木 俊法学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA

    Surface Temperature Dependence of Hydrogen Ortho-Para Conversion on Amorphous Solid Water

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    The surface temperature dependence of the ortho-to-para conversion of H-2 on amorphous solid water is first reported. A combination of photostimulated desorption and resonance-enhanced multiphoton ionization techniques allowed us to sensitively probe the conversion on the surface of amorphous solid water at temperatures of 9.2-16 K. Within a narrow temperature window of 8 K, the conversion time steeply varied from similar to 4.1 x 10(3) to similar to 6.4 x 10(2) s. The observed temperature dependence is discussed in the context of previously suggested models and the energy dissipation process. The two-phonon process most likely dominates the conversion rate at low temperatures
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