275 research outputs found

    Soft X-ray Energy Spectra in the Wide-Field Galactic Disk Area Revealed with HaloSat

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    We analyzed data from HaloSat observations for five fields in the Galactic disk located far away from the Galactic center (135∘^{\circ} << ll << 254∘^{\circ}) to understand the nature of soft X-ray energy emission in the Galactic disk. The fields have 14∘^{\circ} diameter and were selected to contain no significant high-flux X-ray sources. All five HaloSat soft X-ray energy spectra (0.4--7 keV with energy resolution of <<100 eV below 1 keV) show a possibility of the presence of unresolved high-temperature plasma in the Galactic disk (UHTPGD) with a temperature of 0.8--1.0 keV and an emission measure of (8--11)×10−4cm−6pc\times10^{-4} \rm cm^{-6} pc in addition to the soft X-ray diffuse background components mainly studied at higher galactic latitudes (solar wind charge exchange emission, local hot bubble, Milky Way halo emission, and the cosmic X-ray background). This suggests that the UHTPGD is present across the whole Galactic disk. We also observed UHTPGD emission in a region with no bright sources in an {\it XMM-Newton} field contained within one of the {\it HaloSat} fields. The temperature and emission measure are consistent with those measured with {\it HaloSat}. Moreover, the stacked spectra of the X-ray point-like sources and NIR-identified point sources such as stars in the {\it XMM-Newton} field also show a spectral feature similar to the UHTPGD emission. This suggests that the UHTPGD may partly originate from point-like sources such as stars.Comment: Accepted for publication in ApJ. 11 pages and 4 figure

    Excitations in the Halo Nucleus He-6 Following The Li-7(gamma,p)He-6 Reaction

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    A broad excited state was observed in 6-He with energy E_x = 5 +/- 1 MeV and width Gamma = 3 +/- 1 MeV, following the reaction Li-7(gamma,p)He-6. The state is consistent with a number of broad resonances predicted by recent cluster model calculations. The well-established reaction mechanism, combined with a simple and transparent analysis procedure confers considerable validity to this observation.Comment: 3 pages of LaTeX, 3 figures in PostScript, approved for publication in Phys. Rev. C, August, 200

    A tomato xylem sap protein represents a new family of small cysteine-rich proteins with structural similarity to lipid transfer proteins

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    AbstractThe coding sequence of a major xylem sap protein of tomato was identified with the aid of mass spectrometry. The protein, XSP10, represents a novel family of extracellular plant proteins with structural similarity to plant lipid transfer proteins. The XSP10 gene is constitutively expressed in roots and lower stems. The decline of XSP10 protein levels in tomato infected with a fungal vascular pathogen may reflect breakdown or modification by the pathogen

    Enhancement of Cardiac Store Operated Calcium Entry (SOCE) within Novel Intercalated Disk Microdomains in Arrhythmic Disease

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    Store-operated Ca2+ entry (SOCE), a major Ca2+ signaling mechanism in non-myocyte cells, has recently emerged as a component of Ca2+ signaling in cardiac myocytes. Though it has been reported to play a role in cardiac arrhythmias and to be upregulated in cardiac disease, little is known about the fundamental properties of cardiac SOCE, its structural underpinnings or effector targets. An even greater question is how SOCE interacts with canonical excitation-contraction coupling (ECC). We undertook a multiscale structural and functional investigation of SOCE in cardiac myocytes from healthy mice (wild type; WT) and from a genetic murine model of arrhythmic disease (catecholaminergic ventricular tachycardia; CPVT). Here we provide the first demonstration of local, transient Ca2+ entry (LoCE) events, which comprise cardiac SOCE. Although infrequent in WT myocytes, LoCEs occurred with greater frequency and amplitude in CPVT myocytes. CPVT myocytes also evidenced characteristic arrhythmogenic spontaneous Ca2+ waves under cholinergic stress, which were effectively prevented by SOCE inhibition. In a surprising finding, we report that both LoCEs and their underlying protein machinery are concentrated at the intercalated disk (ID). Therefore, localization of cardiac SOCE in the ID compartment has important implications for SOCE-mediated signaling, arrhythmogenesis and intercellular mechanical and electrical coupling in health and disease

    Indirect Study of the 16O+16O Fusion Reaction Toward Stellar Energies by the Trojan Horse Method

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    The 16 O+ 16 O fusion reaction is important in terms of the explosive oxygen burning process during late evolution stage of massive stars as well as understanding of the mechanism of low-energy heavy-ion fusion reactions. We aim to determine the excitation function for the most major exit channels, α + 28 Si and p + 31 P, toward stellar energies indirectly by the Trojan Horse Method via the 16 O( 20 Ne , α 28 Si) α and 16 O( 20 Ne , p 31 P) α three-body reactions. We report preliminary results involving reaction identification, and determination of the momentum distribution of α - 16 O intercluster motion in the projectile 20 Ne nucleus

    Three-body resonances in He-6, Li-6, and Be-6, and the soft dipole mode problem of neutron halo nuclei

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    Using the complex scaling method, the low-lying three-body resonances of 6^6He, 6^6Li, and 6^6Be are investigated in a parameter-free microscopic three-cluster model. In 6^6He a 2+^+, in 6^6Li a 2+^+ and a 1+^+, and in 6^6Be the 0+^+ ground state and a 2+^+ excited state is found. The other experimentally known 2+^+ state of 6^6Li cannot be localized by our present method. We have found no indication for the existence of the predicted 1−^- soft dipole state in 6^6He. We argue that the sequential decay mode of 6^6He through the resonant states of its two-body subsystem can lead to peaks in the excitation function. This process can explain the experimental results in the case of 11^{11}Li, too. We propose an experimental analysis, which can decide between the soft dipole mode and the sequential decay mode.Comment: REVTEX, Submitted to Phys. Rev. C, 12 pages, 2 postscript figures are available upon request. CALTECH, MAP-16

    Halo Excitation of 6^6He in Inelastic and Charge-Exchange Reactions

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    Four-body distorted wave theory appropriate for nucleon-nucleus reactions leading to 3-body continuum excitations of two-neutron Borromean halo nuclei is developed. The peculiarities of the halo bound state and 3-body continuum are fully taken into account by using the method of hyperspherical harmonics. The procedure is applied for A=6 test-bench nuclei; thus we report detailed studies of inclusive cross sections for inelastic 6^6He(p,p')6^6He∗^* and charge-exchange 6^6Li(n,p)6^6He∗^* reactions at nucleon energy 50 MeV. The theoretical low-energy spectra exhibit two resonance-like structures. The first (narrow) is the excitation of the well-known 2+2^+ three-body resonance. The second (broad) bump is a composition of overlapping soft modes of multipolarities 1−,2+,1+,0+1^-, 2^+, 1^+, 0^+ whose relative weights depend on transferred momentum and reaction type. Inelastic scattering is the most selective tool for studying the soft dipole excitation mode.Comment: Submitted to Phys. Rev. C., 11 figures using eps

    State of the Art on Prediction of Concrete Pumping

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    Large scale constructions needs to estimate a possibility for pumping concrete. In this paper, the state of the art on prediction of concrete pumping including analytical and experimental works is presented. The existing methods to measure the rheological properties of slip layer (or called lubricating layer) are first introduced. Second, based on the rheological properties of slip layer and parent concrete, models to predict concrete pumping (flow rate, pumping pressure, and pumpable distance) are explained. Third, influencing factors on concrete pumping are discussed with the test results of various concrete mixes. Finally, future need for research on concrete pumping is suggested.ope
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