Charged Scalar Perturbations around Garfinkle-Horowitz-Strominger Black Holes

We examine the stability of the Garfinkle-Horowitz-Strominger (GHS) black hole under charged scalar perturbations. We find that different from the neutral scalar field perturbations, only two numerical methods, such as the continued fraction method and the asymptotic iteration method, can keep high efficiency and accuracy requirements in the frequency domain computations. The comparisons of the efficiency between these two methods have also been done. Employing the appropriate numerical method, we show that the GHS black hole is always stable against charged scalar perturbations. This is different from the result obtained in the de Sitter and Anti-de Sitter black holes. Furthermore we argue that in the GHS black hole background there is no amplification of the incident charged scalar wave to cause the superradiance, so that the superradiant instability cannot exist in this spacetime.Comment: 24 pages, 5 figure

Superradiant instability of Kerr-de Sitter black holes in scalar-tensor theory

We investigate in detail the mechanism of superradiance to render the instability of Kerr-de Sitter black holes in scalar-tensor gravity. Our results provide more clues to examine the scalar-tensor gravity in the astrophysical black holes in the universe with cosmological constant. We also discuss the spontaneous scalarization in the de Sitter background and find that this instability can also happen in the spherical de Sitter configuration in a special style.Comment: (v2)21 pages, 21 figures; Sec. V revised; This version has been accepted for publication by JHE

Analytic Expression for Exact Ground State Energy Based on an Operator Method for a Class of Anharmonic Potentials

A general procedure based on shift operators is formulated to deal with anharmonic potentials. It is possible to extract the ground state energy analytically using our method provided certain consistency relations are satisfied. Analytic expressions for the exact ground state energy have also been derived specifically for a large class of the one-dimensional oscillator with cubic-quartic anharmonic terms. Our analytical results can be used to check the accuracy of existing numerical methods, for instance the method of state-dependent diagonalization. Our results also agree with the asymptotic behavior in the divergent pertubative expansion of quartic harmonic oscillator.Comment: LaTeX with six figure (gif) files; Submitted to Phys. Rev.

Internal Mammary Sentinel Lymph Node Biopsy

The conception of internal mammary sentinel lymph node biopsy (IM‐SLNB) has been added to the 2009 American Joint Committee on Cancer breast cancer staging manual. However, there has still been slight variation in the surgical treatment model owing to the low visualization rate of internal mammary sentinel lymph nodes (IM‐SLN) with the traditional radiotracer injection technique. According to the hypothesis of IM‐SLN, a modified injection technique (periareolar intraparenchymal, high volume, and ultrasound guidance) was established, which could significantly improve the IM‐SLN visualization rate, and make the IM‐SLNB procedure possible in routine practice. IM‐SLNB could provide minimally invasive staging, prognosis, and decision‐making individually, especially for the patients with clinically positive axilla lymph nodes. Moreover, radiotherapy targeting on internal mammary lymph nodes (IMLN) should be tailored and balanced between the potential benefit and toxicity, and radiotherapy guided by IM‐SLNB could achieve this goal. In the era of emphasizing the effective adjuvant therapy, within the changing therapy approach—more systemic treatment, less loco‐regional treatment—oncologist should reconsider the application of regional IMLN therapy