We present a 100 yr optical lightcurve of the recently discovered supersoft X-ray source RX J0019.8+2156 as deduced from photographic plates of Harvard and Sonneberg Observatory. Apart from the periodic orbital variations two dierent timescales of optical variability are discovered. The timescales and amplitudes of this variability are discussed in the framework of the steady nuclear burning mo...

Many different software reliability model.s have been proposed since the publications of the first mc)dels in 1971 [3,2]. Sufficient work has been done to demonstrate that these methods can be used to monitor reliability growth over a useful range of software development projects. }Iowever, the use of software reliability measurement as a management tool is not as widespread as it might be. Par...