The Characteristic of the Large-amplitude Pulsation in a Model Yellow Supergiant Star

The large-amplitude pulsation of a model yellow supergiant star is investigated by using a hydrodynamic code. The parameters of the model were M=1M_⦿, L=3200L⦿ and T_=5300K. The recurrence of the generation of strong shock wave is obtained in every several pulsation periods. The abrupt decrease of the pulsation period has found after the formation of extended atmospheres above the photosphere. The outer boundary conditions for the linear non-adiabatic approximation derived by Castor fail to reproduce this period

Hydrodynamic Models of Classical Cepheids. II. Two-mode Resonance

The two-mode coupling in hydrodynamic models of classical cepheids is investigated. The centre of resonance is situated at the period ratio P_/P_F=0.49 for a model sequence having 5091 L_⊙ and 5 M_⊙. The phase of bump of the luminosity- and photospheric velocity-curves coincides with the analytical results of two-mode resonance theory. The decrease of amplitude at the resonance centre is also found in the model sequence

A Case of Endoscopic Mucosal Resection of Carcinoma in Adenoma at the Minor Duodenal Papilla

Here, we describe a case of minor papillary adenocarcinoma in adenoma that was treated with endoscopic mucosal resection (EMR). In a 67-year-old woman, sigmoid colon cancer was incidentally detected on preoperative upper gastrointestinal endoscopy. Endoscopy revealed a slightly elevated lesion at the minor duodenal papilla. The findings of a histopathologic examination were suggestive of adenocarcinoma. Computed tomography and magnetic resonance images identified a minute tumor, whereas endoscopic ultrasonography revealed that the tumor did not spread to the pancreas. We performed EMR of this lesion. There were no complications, and relapse has not occurred in 3 years. Cases of minor papillary adenocarcinoma treated with EMR are quite rare

Revision of Pulsation Properties of Yellow Bright Stars

Linear adiabatic periods, which have been mostly used to evaluate the masses of pulsating stars, shouldn\u27t be used for low surface-gravity variable stars, because those differ considerably with linear nonadiabatic periods and nonlinear theoretical periods in some cases. The use of nonadiabatic periods sometimes derive drastically low stellar masses. Taking into account the small occurrence of variable stars at the bluer side of cepheid instability strip on the HR diagram, it may be supposed that most of these variables will be less massive evolved stars

Resonance Phenomenon in Classical Cepheids

To investigate resonance phenomenon in classical cepheids, the non-linear radial oscillation of stars is studied based on the assumption that the non-adiabatic perturbation is expressed in terms of van der Pol\u27s type damping. Two- and three-wave resonance in this system is applied to classical cepheids to describe their bump and double-mode behavior. The phase of bump and the depression of amplitude are explained for bump cepheids. The double-periodicity is shown by the enhancement of the third overtone in three-wave resonance. Non-linear effect on resonant period is also discussed briefly

Hydrodynamic Models of Classical Cepheids. : I. A Technique to Search the Limiting-amplitude Oscillation

The limiting-amplitude of hydrodynamic models for cepheid variables is searched by checking the intrinsic growth-rate of the oscillation derived by the pumping-up. The procedure is scarcely affected by the initial values. The modulation of oscillation appeared at the earlier stage may be enhanced by the overtones in resonance