435 research outputs found

    Photometric and Spectroscopic Observations of the Algol Type Binary V Triangle

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    Time-series, multi-color photometry and high-resolution spectra of the short period eclipsing binary V Tri were obtained by observations. The completely covered light and radial velocity curves of the binary system are presented. All times of light minima derived from both photoelectric and CCD photometry were used to calculate the orbital period and new ephemerides of the eclipsing system. The analysis of OCO-C diagram reveals that the orbital period is 0.58520481 days0.58520481\ days, decreasing at a rate of $dP/dt=-7.80\times10^{-8} d\ yr^{-1} .Themasstransferbetweenthetwocomponentsandthelighttimetraveleffectduetoathirdbodycouldbeusedtoexplaintheperioddecrease.However,asemidetachedconfigurationwiththelessmasscomponentfillingandtheprimarynearlyfillingeachoftheirRochelobeswasderivedfromthesynthesisofthelightandradialvelocitycurvesbyusingthe2015versionoftheWilsonDevinneycode.Weconsidertheperioddecreasetobethenonconservativemasstransferfromthesecondarycomponenttotheprimaryandthemasslossofthesystem,whichwasthoughttobeanEBtypewhileitshouldbeanEAtype(semidetachedAlgoltype)fromourstudy.Themasses,radiiandluminositiesoftheprimaryandsecondaryare. The mass transfer between the two components and the light time-travel effect due to a third body could be used to explain the period decrease. However, a semidetached configuration with the less-mass component filling and the primary nearly filling each of their Roche lobes was derived from the synthesis of the light and radial velocity curves by using the 2015 version of the Wilson-Devinney code. We consider the period decrease to be the nonconservative mass transfer from the secondary component to the primary and the mass loss of the system, which was thought to be an EB type while it should be an EA type (semi-detached Algol-type) from our study. The masses, radii and luminosities of the primary and secondary are 1.60\pm0.07 M_\odot,, 1.64\pm0.02 R_\odot,, 14.14\pm0.73 L_\odotand and 0.74\pm0.02 M_\odot,, 1.23\pm0.02 R_\odot,, 1.65\pm0.05 L_\odot$, respectively.Comment: 11 pages, 6 figures, Accepted for publication by A

    Precise determination of stellar parameters of the ZZ Ceti and DAZ white dwarf GD 133 through asteroseismology

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    An increasing number of white dwarf stars show atmospheric chemical composition polluted by heavy elements accreted from debris disk material. The existence of such debris disks strongly suggests the presence of one or more planet(s) whose gravitational interaction with rocky planetesimals is responsible for their disruption by tidal effect. The ZZ Ceti pulsator and polluted DAZ white dwarf GD 133 is a good candidate for searching for such a potential planet. We started in 2011 a photometric follow-up of its pulsations. As a result of this work in progress, we used the data gathered from 2011 to 2015 to make an asteroseismological analysis of GD 133, providing the star parameters from a best fit model with MM/MM_{\odot} = 0.630 ±\pm 0.002, TeffT_{\rm eff} = 12400 K ±\pm 70 K, log(MHe/MM_{\rm He}/M) = -2.00 ±\pm 0.02, log(MH/MM_{\rm H}/M) = -4.50 ±\pm 0.02 and determining a rotation period of \approx 7 days.Comment: 10 pages, 13 figures, accepted by MNRA

    The Subleading Term of the Strong Coupling Expansion of the Heavy-Quark Potential in a N=4\mathcal N=4 Super Yang-Mills Plasma

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    Applying the AdS/CFT correspondence, the expansion of the heavy-quark potential of the N{\cal N} supersymmetric Yang-Mills theory at large NcN_c is carried out to the sub-leading term in the large 't Hooft coupling at nonzero temperatures. The strong coupling corresponds to the semi-classical expansion of the string-sigma model, the gravity dual of the Wilson loop operator, with the sub-leading term expressed in terms of functional determinants of fluctuations. The contributions of these determinants are evaluated numerically.Comment: 17 pages in JHEP3, typos fixed, updated version to be published in JHE

    Calcium release through P2X4 activates calmodulin to promote endolysosomal membrane fusion

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    Intra-endolysosomal Ca(2+) release is required for endolysosomal membrane fusion with intracellular organelles. However, the molecular mechanisms for intra-endolysosomal Ca(2+) release and the downstream Ca(2+) targets involved in the fusion remain elusive. Previously, we demonstrated that endolysosomal P2X4 forms channels activated by luminal adenosine triphosphate in a pH-dependent manner. In this paper, we show that overexpression of P2X4, as well as increasing endolysosomal P2X4 activity by alkalinization of endolysosome lumen, promoted vacuole enlargement in cells and endolysosome fusion in a cell-free assay. These effects were prevented by inhibiting P2X4, expressing a dominant-negative P2X4 mutant, and disrupting the P2X4 gene. We further show that P2X4 and calmodulin (CaM) form a complex at endolysosomal membrane where P2X4 activation recruits CaM to promote fusion and vacuolation in a Ca(2+)-dependent fashion. Moreover, P2X4 activation-triggered fusion and vacuolation were suppressed by inhibiting CaM. Our data thus suggest a new molecular mechanism for endolysosomal membrane fusion involving P2X4-mediated endolysosomal Ca(2+) release and subsequent CaM activation

    NOx and ultrafine particle emission characteristics in a new steel slag modification device

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    Two density-separated Chinese coals and steel slag were prepared and then combusted in a modification furnace with different excess air ratio. Non-staged and Fuel-staged combustion experiments were compared under different pulverized coal mixing ratios. Thus, in the fuel-staged combustion experiments, the concentration of NOx in the flue gas was found to greatly decrease under a bitumite: anthracite mixing ratio of 1:1 and an air excess coefficient of 1,2 under the fuel-staged ratio is 15:85. The flue gas temperature was as high as 1 615 °C, while the NOx concentration in the flue gas was as low as 320 mg/m3. Compared with the other types of burners, the experimental combustion device designed herein efficiently reduced the NOx emissions ca. 80%. Fuel-staged combustion has a significant effect on reducing particulate matter (PM) emissions, and a suitable coal ratio was also beneficial for reducing particulate matter emissions

    Improved isolation of cadmium from paddy soil by novel technology based on pore water drainage with graphite-contained electro-kinetic geosynthetics

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    Novel soil remediation equipment based on electro-kinetic geosynthetics (EKG) was developed for in situ isolation of metals from paddy soil. Two mutually independent field plot experiments A and B (with and without electric current applied) were conducted. After saturation using ferric chloride (FeCl3) and calcium chloride (CaCl2), soil water drainage capacity, soil cadmium (Cd) removal performance, energy consumption as well as soil residual of iron (Fe) and chloride (Cl) were assessed. Cadmium dissolved in the soil matrix and resulted in a 100% increase of diethylenetriamine-pentaacetic acid (DTPA) extracted phyto-available Cd. The total soil Cd content reductions were 15.20% and 26.58% for groups A and B, respectively, and electric field applications resulted in a 74.87% increase of soil total Cd removal. The electric energy consumption was only 2.17 kWh/m3 for group B. Drainage by gravity contributed to > 90% of the overall soil dewatering capacity. Compared to conventional electro-kinetic technology, excellent and fast soil water drainage resulted in negligible hydrogen ion (H+) and hydroxide ion (OH−) accumulation at nearby electrode zones, which addressed the challenge of anode corrosion and cathode precipitation of soil metals. External addition of FeCl3 and CaCl2 caused soil Fe and Cl residuals and led to 4.33–7.59% and 139–172% acceptable augments in soil total Fe and Cl content, correspondingly, if compared to original untreated soils. Therefore, the novel soil remediation equipment developed based on EKG can be regarded as a promising new in situ technology for thoroughly isolating metals from large-scale paddy soil fields

    Controlled reduction of photobleaching in DNA origami gold nanoparticle hybrids

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    The amount of information obtainable from a fluorescence-based measurement is limited by photobleaching: Irreversible photochemical reactions either render the molecules nonfluorescent or shift their absorption and/or emission spectra outside the working range. Photobleaching is evidenced as a decrease of fluorescence intensity with time, or in the case of single molecule measurements, as an abrupt, single-step interruption of the fluorescence emission that determines the end of the experiment. Reducing photobleaching is central for improving fluorescence (functional) imaging, single molecule tracking, and fluorescence-based biosensors and assays. In this single molecule study, we use DNA self-assembly to produce hybrid nanostructures containing individual fluorophores and gold nanoparticles at a controlled separation distance of 8.5 nm. By changing the nanoparticles? size we are able to systematically increase the mean number of photons emitted by the fluorophores before photobleaching.Fil: Pellegrotti, Jesica Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Acuña, Guillermo. Technische Universität Braunschweig. Institute for Physical and Theoretical Chemistry. NanoBioSciences Group; AlemaniaFil: Puchkova, Anastasiya. Technische Universität Braunschweig. Institute for Physical and Theoretical Chemistry. NanoBioSciences Group; AlemaniaFil: Holzmeister, Phil. Technische Universität Braunschweig. Institute for Physical and Theoretical Chemistry. NanoBioSciences Group; AlemaniaFil: Gietl, Andreas. Technische Universität Braunschweig. Institute for Physical and Theoretical Chemistry. NanoBioSciences Group; AlemaniaFil: Lalkens, Birka. Technische Universität Braunschweig. Institute for Physical and Theoretical Chemistry. NanoBioSciences Group; AlemaniaFil: Stefani, Fernando Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Tinnefeld, Philip. Technische Universität Braunschweig. Institute for Physical and Theoretical Chemistry. NanoBioSciences Group; Alemani
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