A search for short time-scale I-band variability in ultracool dwarfs

76 hours of CCD photometry of 11 L dwarfs and one T dwarf is described. Three objects, including the T dwarf ε Indi B, showed convincing evidence for variability. A periodicity of 8 h is clearly visible in the light curve of 2MASS J1155395−372735.     

基于J2EE的数据通用性操作框架的研究与实现

数据操作是基于J2EE的多级应用开发中常见而又具有通用性的重要一部分，而框架技术的研究可以实现软件开发过程中的重用，提高软件开发效率和质量。通过对国内外成熟的开发框架进行研究，并综合各自的优点形成一套在开发中可以保证数据操作模块具有可重用、可扩展、稳定性好等优势的方案；同时结合电子政务中的一个应用实例给出了数据通用性操作框架技术在企业级开发中的具体实现。     

J2EE在电力系统工作票信息化管理中的应用--从C/S模式到B/S多层模式的转换

介绍了传统C／S模式在电力工作票管理信息系统中的应用及其问题，同时介绍J2EE多层分布式体系结构在工作票管理系统中应用的可行性。通过对传统C／S电力系统工作票管理系统的分析，提出将J2EE应用于工作票管理系统的思想并进行实践。     

Timing of the accreting millisecond pulsar XTE J1814−338

We present a precise timing analysis of the accreting millisecond pulsar XTE J1814−338 during its 2003 outburst, observed by RXTE . A full orbital solution is given for the first time; Doppler effects induced by the motion of the source in the binary system were corrected, leading to a refined estimate of the orbital period,   P _orb= 15 388.7229(2)  s, and of the projected semimajor axis,   a sin  i / c = 0.390633(9)  light-second. We could then investigate the spin behaviour of the accreting compact object during the outburst. We report here a refined value of the spin frequency  (ν= 314.356 108 79(1) Hz)  and the first estimate of the spin frequency derivative of this source while accreting     . This spin-down behaviour arises when both the fundamental frequency and the second harmonic are taken into consideration. We discuss this in the context of the interaction between the disc and the quickly rotating magnetosphere, at accretion rates sufficiently low to allow a threading of the accretion disc in regions where the Keplerian velocity is slower than the magnetosphere velocity. We also present indications of a jitter of the pulse phases around the mean trend, which we argue results from movements of the accreting hotspots in response to variations of the accretion rate.     

The anatomy of a magnetar: XMM monitoring of the transient anomalous X-ray pulsar XTE J1810–197

We present the latest results from a multi-epoch timing and spectral study of the Transient Anomalous X-ray Pulsar XTE J1810–197. We have acquired seven observations of this pulsar with the Newton X-ray Multi-mirror Mission (XMM-Newton) over the course of two and a half years, to follow the spectral evolution as the source fades from outburst. The spectrum is arguably best characterized by a two-temperature blackbody whose luminosities are decreasing exponentially with τ ₁=870 d and τ ₂=280 d, respectively. The temperatures of these components are currently cooling at a rate of 22% per year from a nearly constant value recorded at earlier epochs of kT ₁=0.25 keV and kT ₂=0.67 keV, respectively. The new data show that the temperature T ₁ and luminosity of that component have nearly returned to their historic quiescent levels and that its pulsed fraction, which has steadily decreased with time, is now consistent with the previous lack of detected pulsations in quiescence. We also summarize the detections of radio emission from XTE J1810–197, the first confirmed for any AXP. We consider possible models for the emission geometry and mechanisms of XTE J1810–197. XMM-Newton is an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. This research is supported by XMM-Newton grant NNG05GJ61G and NASA ADP grant ADP04-0059-0024.     

Jet disc coupling in black hole binaries

In the last decade multi-wavelength observations have demonstrated the importance of jets in the energy output of accreting black hole binaries. The observed correlations between the presence of a jet and the state of the accretion flow provide important information on the coupling between accretion and ejection processes. After a brief review of the properties of black hole binaries, I illustrate the connection between accretion and ejection through two particularly interesting examples. First, an INTEGRAL observation of Cygnus X-1 during a ‘mini-’ state transition reveals disc jet coupling on time scales of orders of hours. Second, the black hole XTEJ1118+480 shows complex correlations between the X-ray and optical emission. Those correlations are interpreted in terms of coupling between disc and jet on time scales of seconds or less. Those observations are discussed in the framework of current models.