The Period Variation of V839 Oph

In this study we present the results of the preliminary analysis of the period variation of V839 Oph based on the extensive series of minima times collected from the literature. The character of the (O–C) diagram can be approximated with a cyclic variation superimposed on a quadratic variation. The quadratic variation can be explained in terms of mass exchange/loss mechanism in the system, while the cyclic variation could be attributed to the light-time effect of a gravitationally bound third body to the system or the magnetic activity cycle of the primary component.     

Cenozoic ultrahigh-temperature metamorphism in pelitic granulites from the Mogok metamorphic belt,Myanmar

Science China Earth Sciences - Ultrahigh-temperature (UHT) metamorphism is critical for understanding the most extreme thermal evolution of continental crust. However, UHT metamorphism...     

Composition of ciliate fauna and its seasonal changes in fluvial drift

Ciliate composition and its seasonal changes in seston depending on the discharge regime were analyzed in the lower rhithral area of the river Sava. Higher values for ciliate density, dry biomass, index of species diversity and concentration of particulate organic matter (POM) were associated with discharge peaks. Using the power model: y = ax^b ± c a significant positive correlation was found between POM and ciliate dry biomass (as dependent variables) and discharge (as independent variable). The ciliate drift constitutes 0.78% of the total annual POM transport. Depending on the discharge regime, the composition of ciliate drift reflects the temporal and structural changes in periphytic community.     

Orbital period variation of the eclipsing binary system TT Herculis

New photoelectric UBV observations were obtained for the eclipsing binary TT Her at the Ankara University Observatory (AUO) and three new times of minima were calculated from these observations. The (O – C) diagram constructed for all available times of minima of TT Her exhibits a cyclic character superimposed on a quadratic variation. The quadratic character yields an orbital period decrease with a rate of dP /dt = –8.83 × 10^–8 day yr^–1 which can be attributed to the mass exchange/loss mechanism in the system. By assuming the presence of a gravitationally bound third body in the system, the analysis of the cyclic nature in the (O – C) diagram revealed a third body with a mass of 0.21M_⊙ orbiting around the eclipsing pair. The possibility of magnetic activity cycle effect as a cause for the observed cyclic variation in the (O – C) diagram was also discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

海水养殖水体中的病害纤毛虫

对黄渤海区海珍品育苗、养殖水体中的致病性纤毛虫的区系构成、分布、危害及防治措施做了初步探讨,给出了迄今所知的在上述水域内检出的72种自由生、共栖生、寄生和周丛生种类的相对数量和名称。     

Monitoring Possible Light-Time Effect in the Orbital Period of Some Eclipsing Binaries at the Ankara University Observatory

A significant number of close binaries are known to be members of physically bound triple or multiple star systems. The O – C analysis technique which is based on the minima times of an eclipsing binary can reveal the light-time effect due to the presence of gravitationally bound and generally unseen close component(s) in the system. In this study we present shortly the O – C analysis results based on the light-time effect possibilities for two of the eclipsing binaries observationally followed by our group; TZ Boo and CF Tau.     

川西平武县虎牙地区旅游扶贫初步研究

旅游扶贫具有其它扶贫方式不可替代的优越性,是各级政府减贫的重要手段。平武县虎牙地区位于四川盆地西部,是一个以藏族为主的少数民族贫困社区。该区旅游资源丰富,品味极高,具有发展旅游的天然优势。由于政府角色缺失、多头管理等原因,当地资源优势并没有转化为经济优势,少量居民自发的、守株待兔式的参与旅游,从中获利甚少。现阶段当地政府应转变职能,在保护生态环境的前提下,实施旅游扶贫。     

Possible Light-Time Effect in the Eclipsing Binary System TY Boo

The O − C diagram for the eclipsing binary system TY Boo was constructed with the new minima times observed at the Ankara University Observatory along with the collected ones from the literature. The O − C diagram shows a cyclic variation superimposed on a quadratic variation. The quadratic variation can be explained in terms of mass loss/exchange mechanism in the system while the cyclic variation is attributed to a possible light-time effect caused by a third body revolving around the close binary.     

1990 photometry of a small amplitude W UMa system LS Delphini

DifferentialUBV observations, carried out in 1990 observing season, of a small amplitude (0 _. ^m 15 inV andB) W UMa system LS Del = HD 199497 are presented. Wavelength-dependent light variations from cycle to cycle indicate that the system is in a very active phase, probably due to magnetic flare activity or mass transfer in the system. An analysis of the minima times indicate a probable secular increase of the photometric period which requires a mass transfer from less massive to more massive component. If this is true then the reverse-algol model by Liuet al. (1988) for this system would not be valid.