1,339 research outputs found

    The implications from CANGAROO-III observations of TeV blazar PKS 2155-304

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    We have observed the high-frequency-peaked BL Lacertae object PKS2155-304 in 2004, 2005 and 2006 with the CANGAROO-III imaging atmospheric Cherenkov telescope, and have detected a signal above 660 GeV at the 4.8/sigma level during the 2006 outburst period. Intranight flux variability on time scale of half an hour is observed. From this variability time scale, the size of the TeV gamma-ray emission region is restricted to 5x10^13\delta cm, and the super massive black hole mass is estimated to be less than 1.9x10^8\delta M_{Solar}, where \delta is the beaming factor. The differential energy spectrum is obtained, and an upper limit of the extragalactic infrared background light (EBL) flux is derived under some assumption. We also fit a synchrotron self Compton (SSC) model to the spectral energy distribution (SED) and derive the beaming factor and magnetic field strength.Comment: 4 pages, 5 figures, proceedings of the "4th Heidelberg International Symposium on High Energy Gamma-Ray Astronomy" July 7-11, 2008, Heidelberg, German

    Apply of Textmining Method to Study the Roles in Improving the Health by Lactoferrin, a Multi-Functional Milk Protein

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    Lactoferrin is a metal-binding glycoprotein found in milk, blood and other exocrine secretions. This is a multi-functional protein that exhibits many activities such as: anti-microbial, anti-viral, immunomodulatory, anti-inflammatory, anti-tumor, anti-metastatic, cell growth-promoting, and anti-oxidant activities, as well as regulation of granulopoiesis and iron absorption, etc. To date, a number of academic reports concerning the biological activities of lactoferrin have been published and are easily accessible through public databases. In order to overcome the information overload associated with lactoferrin information, we have applied the text mining method to the accumulated lactoferrin literature. To this end, we used the information extraction system GENPAC (provided by Nalapro Technologies Inc., Tokyo), which uses natural language processing and text mining technology. Using GENPAC, text extraction was carried out on literature containing the term “lactoferrin” and any of keywords concerning health conditions or diseases from PubMed. Subsequently, network mappings of the information obtained were produced using Cytoscape. We will exhibit that such textmining method and information visualization analysis is useful in studying novel relationships among a multitude of lactoferrin functions and mechanisms to improve our health

    Oral Appliance Treatment for Obstructive Sleep Apnea: An Update

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    Oral appliances (OA) have emerged as an alternative to continuous positive airway pressure (CPAP) for obstructive sleep apnea (OSA) treatment. The most commonly used OA reduces upper airway collapse by advancing the mandible (OAm). There is a strong evidence base demonstrating OAm improve OSA in the majority of patients, including some with more severe disease. However OAm are not efficacious for all, with approximately one-third of patients experiencing no therapeutic benefit. OAm are generally well tolerated, although short-term adverse effects during acclimatization are common. Long-term dental changes do occur, but these are for the most part subclinical and do not preclude continued use. Patients often prefer OAm to gold-standard CPAP treatment. Head-to-head trials confirm CPAP is superior in reducing OSA parameters on polysomnography; however, this greater efficacy does not necessarily translate into better health outcomes in clinical practice. Comparable effectiveness of OAm and CPAP has been attributed to higher reported nightly use of OAm, suggesting that inferiority in reducing apneic events may be counteracted by greater treatment adherence. Recently, significant advances in commercially available OAm technologies have been made. Remotely controlled mandibular positioners have the potential to identify treatment responders and the level of therapeutic advancement required in single night titration polysomnography. Objective monitoring of OAm adherence using small embedded temperature sensing data loggers is now available and will enhance clinical practice and research. These technologies will further enhance efficacy and effectiveness of OAm treatment for OSA

    Reanalysis of Data Taken by the CANGAROO 3.8 Meter Imaging Atmospheric Cherenkov Telescope: PSR B1706-44, SN 1006, and Vela

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    We have reanalyzed data from observations of PSR B1706-44, SN 1006, and the Vela pulsar region made with the CANGAROO 3.8 m imaging atmospheric Cherenkov telescope between 1993 and 1998 in response to the results reported for these sources by the H.E.S.S. collaboration. In our reanalysis, in which gamma-ray selection criteria have been determined exclusively using gamma-ray simulations and OFF-source data as background samples, no significant TeV gamma-ray signals have been detected from compact regions around PSR B1706-44 or within the northeast rim of SN 1006. We discuss reasons why the original analyses gave the source detections. The reanalysis did result in a TeV gamma-ray signal from the Vela pulsar region at the 4.5 sigma level using 1993, 1994, and 1995 data. The excess was located at the same position, 0.13 deg. to the southeast of the Vela pulsar, as that reported in the original analysis. We have investigated the effect of the acceptance distribution in the field of view of the 3.8 m telescope, which rapidly decreases toward the edge of the field of the camera, on the detected gamma-ray morphology. The expected excess distribution for the 3.8 m telescope has been obtained by reweighting the distribution of HESS J0835-455 measured by H.E.S.S. with the acceptance of the 3.8 m telescope. The result is morphologically comparable to the CANGAROO excess distribution, although the profile of the acceptance-reweighted H.E.S.S. distribution is more diffuse than that of CANGAROO. The integral gamma-ray flux from HESS J0835-455 has been estimated for the same region as defined by H.E.S.S. from the 1993-1995 data of CANGAROO to be F(> 4.0 +/- 1.6 TeV) = (3.28 +/- 0.92) x 10^{-12} photons cm^{-2} s^{-1}, which is statistically consistent with the integral flux obtained by H.E.S.S.Comment: Published in ApJ, minor improvement

    Simulating Cherenkov Telescope Array observation of RX J1713.7-3946

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    We perform simulations of Cherenkov Telescope Array (CTA) observations of a young supernova remnant RX J1713.7-3946. This target is not only one of the brightest sources ever discovered in very high-energy gamma rays but also well observed in other wavebands. In X-rays, the emission is dominated by synchrotron radiation, which links directly to the existence of high-energy electrons. Radio observations of CO and HI gas have revealed a highly inhomogeneous medium surrounding the SNR, such as clumpy molecular clouds. Therefore gamma rays from hadronic interactions are naturally expected. However, the spectrum in GeV energy range measured by Fermi/LAT indicates more typical of leptonic emission from accelerated electrons. Despite lots of multi-wavelength information, the competing interpretations have led to much uncertainty in the quest of unraveling the true origin of the gamma-ray emission from RX~J1713.7--3946. CTA will achieve highest performance ever in sensitivity, angular resolution, and energy resolution. We estimate CTA capability to examine the emission mechanisms of the gamma rays through simulated spatial distribution, spectra, and their time variation.Comment: 8 pages, 3 figures. In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

    Design Study of CANGAROO-III, Stereoscopic Imaging Atmospheric Cherenkov Telescopes for sub-TeV Gamma-ray

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    CANGAROO-III is an Imaging Atmospheric Cherenkov Telescope (IACT) array of four 10 m telescopes for very high energy (sub-TeV) gamma-ray astronomy. A design study of the CANGAROO-III telescope system was carried out using the Monte Carlo technique in order to optimize the pixel size and the telescope spacing. Studies were also made of observations at low elevation angles.Comment: 17pages, 13 figures, elsart, to appear in Astro. Part. Phy

    CANGAROO-III Observation of TeV Gamma Rays from the vicinity of PSR B1 706-44

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    Observation by the CANGAROO-III stereoscopic system of the Imaging Cherenkov Telescope has detected extended emission of TeV gamma rays in the vicinity of the pulsar PSR B1706−-44. The strength of the signal observed as gamma-ray-like events varies when we apply different ways of emulating background events. The reason for such uncertainties is argued in relevance to gamma-rays embedded in the "off-source data", that is, unknown sources and diffuse emission in the Galactic plane, namely, the existence of a complex structure of TeV gamma-ray emission around PSR B1706−-44.Comment: 10 pages, 13 figures, to be published in Ap
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