1,343 research outputs found

    Analytical solution of the geodesic equation in Kerr-(anti) de Sitter space-times

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    The complete analytical solutions of the geodesic equations in Kerr-de Sitter and Kerr-anti-de Sitter space-times are presented. They are expressed in terms of Weierstrass elliptic p, zeta, and sigma functions as well as hyperelliptic Kleinian sigma functions restricted to the one-dimensional theta-divisor. We analyze the dependency of timelike geodesics on the parameters of the space-time metric and the test-particle and compare the results with the situation in Kerr space-time with vanishing cosmological constant. Furthermore, we systematically can find all last stable spherical and circular orbits and derive the expressions of the deflection angle of flyby orbits, the orbital frequencies of bound orbits, the periastron shift, and the Lense-Thirring effect.Comment: 18 pages, 11 figure

    An X-ray Spectroscopic Study of the Hot Interstellar Medium Toward the Galactic Bulge

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    We present a detailed spectroscopic study of the hot gas toward the Galactic bulge along the 4U 1820-303 sight line by a combination analysis of emission and absorption spectra. In addition to the absorption lines of OVII Kalpha, OVII Kbeta, OVIII Kalpha and NeIX Kalpha by Chandra LTGS as shown by previous works, Suzaku detected clearly the emission lines of OVII, OVIII, NeIX and NeX from the vicinity. We used simplified plasma models with constant temperature and density. Evaluation of the background and foreground emission was performed carefully, including stellar X-ray contribution based on the recent X-ray observational results and stellar distribution simulator. If we assume that one plasma component exists in front of 4U1820-303 and the other one at the back, the obtained temperatures are T= 1.7 +/- 0.2 MK for the front-side plasma and T=3.9(+0.4-0.3) MK for the backside. This scheme is consistent with a hot and thick ISM disk as suggested by the extragalactic source observations and an X-ray bulge around the Galactic center.Comment: 14 pages, 15 figures, accepted to be published in PASJ (Replace figure files to fix latex problem

    Characterizing Planetary Orbits and the Trajectories of Light

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    Exact analytic expressions for planetary orbits and light trajectories in the Schwarzschild geometry are presented. A new parameter space is used to characterize all possible planetary orbits. Different regions in this parameter space can be associated with different characteristics of the orbits. The boundaries for these regions are clearly defined. Observational data can be directly associated with points in the regions. A possible extension of these considerations with an additional parameter for the case of Kerr geometry is briefly discussed.Comment: 49 pages total with 11 tables and 10 figure

    Symmetry, bifurcation and stacking of the central configurations of the planar 1+4 body problem

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    In this work we are interested in the central configurations of the planar 1+4 body problem where the satellites have different infinitesimal masses and two of them are diametrically opposite in a circle. We can think this problem as a stacked central configuration too. We show that the configuration are necessarily symmetric and the other sattelites has the same mass. Moreover we proved that the number of central configuration in this case is in general one, two or three and in the special case where the satellites diametrically opposite have the same mass we proved that the number of central configuration is one or two saying the exact value of the ratio of the masses that provides this bifurcation.Comment: 9 pages, 2 figures. arXiv admin note: text overlap with arXiv:1103.627

    燒炭自殺在東亞國家的流行散佈: 趨勢分析

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    The Abstract Book can be viewed at: http://www.sop.org.tw/book/download/Summary2013.pdfConference Theme: Focusing on Mental Health, Life Care and Social Network in the ElderlyObjective: Suicides by carbon monoxide poisoning resulting from burning barbecue charcoal reached epidemic levels in Hong Kong and Taiwan within 5 years in the early 2000s. Methods: We used data for suicides by gases other than domestic gas in Hong Kong, Japan, South Korea (1995-2010), Taiwan (1995-2011), and Singapore (1996-2011) to systematically investigate the spread of this method in East Asia. Graphical and joinpoint regression analyses were used to examine suicide trends and Poisson regression analysis to study sex- and age-specific patterns. Results: In 1995/1996, charcoal-burning suicides accounted for < 1% of all suicides in all study countries, except around 5% in Japan, but they increased to account for 14%, 28%, 13%, 4.3%, and 3.4% of all suicides in Hong Kong, Taiwan, Japan, South Korea, and Singapore respectively in 2010. Rises were first seen in Hong Kong in 1999, followed by Singapore in 2000, Taiwan in 2001, Japan in 2003, and South Korea in 2008. There was some evidence for an impact on overall suicide trends in Hong Kong, Taiwan, and Japan (females), but not in Japan (males), South Korea, and Singapore. Rates of change did not differ by sex/age group in Taiwan and Hong Kong but were greatest in young people in Japan and middleaged men and young women in South Korea. Conclusion: Variations in the timing, scale and sex/age pattern of the epidemic appear to be influenced by the media reporting of charcoal-burning suicide, whilst other factors such as the characteristics of the first or first few cases, language and ulture, familiarity and accessibility with the method, and socio-economic conditions may also play a role. Strategies to limit the epidemic spread of new suicide methods include surveillance to enable the early identification of the emergence of such methods, responsible media reporting and restrictions on Internet sites giving technical information about the method

    Orbits in the Field of a Gravitating Magnetic Monopole

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    Orbits of test particles and light rays are an important tool to study the properties of space-time metrics. Here we systematically study the properties of the gravitational field of a globally regular magnetic monopole in terms of the geodesics of test particles and light. The gravitational field depends on two dimensionless parameters, defined as ratios of the characteristic mass scales present. For critical values of these parameters the resulting metric coefficients develop a singular behavior, which has profound influence on the properties of the resulting space-time and which is clearly reflected in the orbits of the test particles and light rays.Comment: 24 pages, 15 figures. Accepted for publication in GR

    Geodesic equations and algebro-geometric methods

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    For an investigation of the physical properties of gravitational fields the observation of massive test particles and light is very useful. The characteristic features of a given space-time may be decoded by studying the complete set of all possible geodesic motions. Such a thorough analysis can be accomplished most effectively by using analytical methods to solve the geodesic equation. In this contribution, the use of elliptic functions and their generalizations for solving the geodesic equation in a wide range of well known space-times, which are part of the general Pleba\'nski-Demia\'nski family of solutions, will be presented. In addition, the definition and calculation of observable effects like the perihelion shift will be presented and further applications of the presented methods will be outlined.Comment: 8 pages, no figures; based on presentation at the conference "Relativity and Gravitation: 100 Years after Einstein in Prague," Prague, 2012. Relativity and Gravitation, volume 157 of Springer Proceedings in Physics, p 91. Springer International Publishing, 201

    The complete set of solutions of the geodesic equations in the space-time of a Schwarzschild black hole pierced by a cosmic string

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    We study the geodesic equations in the space-time of a Schwarzschild black hole pierced by an infinitely thin cosmic string and give the complete set of analytical solutions of these equations for massive and massless particles, respectively. The solutions of the geodesic equations can be classified according to the particle's energy and angular momentum, the ratio between the component of the angular momentum aligned with the axis of the string and the total angular momentum, the deficit angle of the space-time and as well the horizon radius (or mass) of the black hole. For bound orbits of massive test particles we calculate the perihelion shift, we discuss light deflection and comment on the Newtonian limit.Comment: 21 pages; section 3 shortened, references added; accepted for publication in Phys. Rev.

    Characterization of metal-insulator-semicomductor capacitors with insulating nitride films grown on 4H-SiC

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    ArticleJAPANESE JOURNAL OF APPLIED PHYSICS. 47(1):676-678(2008)journal articl
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