The Distribution of Stellar Orbits in the Giant Elliptical Galaxy NGC 2320

We present direct observational constraints on the orbital distribution of the stars in the giant elliptical NGC 2320. Long-slit spectra along multiple position angles are used to derive the stellar line-of-sight velocity distribution within one effective radius. In addition, the rotation curve and dispersion profile of an ionized gas disk are measured from the [OIII] emission lines. After correcting for the asymmetric drift, we derive the circular velocity of the gas, which provides an independent constraint on the gravitational potential. To interpret the stellar motions, we build axisymmetric three-integral dynamical models based on an extension of the Schwarzschild orbit- superposition technique. We consider two families of gravitational potential, one in which the mass follows the light (i.e. no dark matter) and one with a logarithmic gravitational potential. Using chi^2-statistics, we compare our models to both the stellar and gas data to constrain the value of the V-band mass-to-light ratio Upsilon-V. We find Upsilon-V = 15.0 \pm 0.6 h75 for the mass-follows-light models and Upsilon-V = 17.0 \pm 0.7 h75 for the logarithmic models. For the latter, Upsilon-V is defined within a sphere of 15'' radius. Models with radially constant Upsilon-V and logarithmic models with dark matter provide comparably good fits to the data and possess similar dynamical structure. Across the full range of Upsilon-V permitted by the observational constraints, the models are radially anisotropic in the equatorial plane over the radial range of our kinematical data (1'' < r < 40''). Along the true minor axis, they are more nearly isotropic. (abridged)Comment: 26 pages, 13 figures, accepted for publication in the Astrophysical Journa

Dynamical Modeling of Velocity Profiles: The Dark Halo Around the Elliptical Galaxy NGC2434

We describe a powerful technique to model and interpret the stellar line-of-sight velocity profiles of galaxies. Following Schwarzschild's modeling approach, a representative library of orbits is calculated in a given potential; then the non-negative superposition of these orbits is determined to fit best a given set of observational constraints. Our implementation incorporates several new features: (i) we calculate velocity profiles and represent them by a Gauss-Hermite series. This allows us to constrain the orbital anisotropy in the fit. (ii) we take into account the error on each observational constraint to obtain an objective chi2 measure for the quality-of-fit. Only projected, observable quantities are included in the fit, and aperture binning and seeing convolution of the data are properly taken into account. This scheme is valid for any geometry, but here we focus on spherical geometry and the issue of dark halos around elliptical galaxies. We model radially extended velocity profiles of the E0 galaxy NGC 2434, and find that constant M/L models are clearly ruled out, regardless of the orbital anisotropy. To study how much dark matter is needed, we considered a sequence of cosmologically motivated `star+halo' potentials, which are specified by the stellar mass-to-light ratio Gamma and the characteristic halo velocity, V_200 (from Navarro et al. 1996). The star+halo models provide an excellent fit to the data, with Gamma=3.35+-0.25 (in B-band solar units) and V_200=450+-100km/s. The best-fitting potential has a circular velocity Vc that is constant (at ~300km/s) to within 10% between 0.2--3 effective radii. In NGC 2434 roughly half of the mass within an effective radius appears to be dark.Comment: 41 pages, Latex file with 11 PostScripts figures. Submitted to the Astrophysical Journa

Evidence for a massive BH in the S0 galaxy NGC 4342

We present axisymmetric dynamical models of the edge-on S0 galaxy NGC 4342. A combination of observations from the ground and with the Hubble Space Telescope (HST) has shown that NGC 4342 rotates rapidly and has a strong central increase in velocity dispersion. We construct simple two-integral Jeans models as well as fully general, three-integral models. The latter are built using a modified version of Schwarzschild's orbit-superposition technique. The two-integral Jeans models suggest a black hole (BH) mass between 3 and 6x10^8 Msun, depending on the data set used to constrain the model, but they fail to fit the details of the observed kinematics. The three-integral models can fit all ground-based and HST data simultaneously, but only when a central BH is included. Models without BH are ruled out to a confidence level better than 99.73 per cent. We determine a BH mass of 3x10^8 Msun. This corresponds to 2.6 per cent of the total mass of the bulge, making NGC 4342 one of the galaxies with the highest BH mass to bulge mass ratio currently known. The models that best fit the data do not have a two-integral phase-space distribution function. They have rather complex dynamical structures: the velocity anisotropies are strong functions of radius reflecting the multi-component structure of this galaxy. The best fit model without BH tries to fit the high central velocity dispersion by placing stars on radial orbits. The measured rotation velocities, however, restrict the amount of radial anisotropy such that the central velocity dispersion measured with the HST can only be fit when a massive BH is included in the models.Comment: 47 pages, 14 figures (postscript). Submitted to Ap

New treatments for chronic hepatitis C

Treatments for chronic hepatitis C has evolved significantly in the past 15 years. The standard of care (SOC) is peginterferon alfa-2a/-2b with ribavirin for 48 weeks or 24 weeks in patients infected with HCV genotype 1 or 2/3, respectively. The treatment duration can be individualized based on the baseline viral load and the speed of the virologic response during treatment. However, current therapies are associated with side effects, complications, and poor patient tolerability. Therefore, there is an urgent need to identify better strategies for treating this disease. An improved sustained virologic response (SVR) can be achieved with new HCV-specific inhibitors against NS3/4A and NS5B polymerases. Recent trials have found SVR rates in patients with HCV genotype 1 infection of 61~68% and 67~75% for combining the SOC with the protease inhibitors telaprevir and boceprevir, respectively. Several new HCV-specific inhibitors such as protease inhibitors and nucleoside and non-nucleoside polymerase inhibitors as well as non-HCV-specific compounds with anti-HCV activity are currently in clinical evaluation. In this review we discuss these new treatments for chronic hepatitis C

Linked data based framework for tourism decision support system ::case study of chinese tourists in Switzerland

Switzerland is one of the most desirable European destinations for Chinese tourists; therefore, a better understanding of Chinese tourists is essential for successful business practices. In China, the largest and leading social media platform—Sina Weibo, a hybrid of Twitter and Facebook—has more than 600 million users. Weibo’s great market penetration suggests that tourism operators and markets need to understand how to build effective and sustainable communications on Chinese social media platforms. In order to offer a better decision support platform to tourism destination managers as well as Chinese tourists, we proposed a framework using linked data on Sina Weibo. Linked Data is a term referring to using the Internet to connect related data. We will show how it can be used and how ontology can be designed to include the users’ context (e.g., GPS locations). Our framework will provide a good theoretical foundation for further understand Chinese tourists’ expectation, experiences, behaviors and new trends in Switzerland