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We explain some phenomena existing generally in the timing residuals: amplitude and sign of the second derivative of a pulsar's spin-frequency (?), some sophisticated residual patterns, which also change with the time span of data segments. The sample is taken from Hobbs et al., in which the pulsar's spin-frequency and its first derivative have been subtracted from the timing solution fitting. We first classify the timing residual patterns into different types based on the sign of ? . Then we use the magnetic field oscillation model developed in our group to fit successfully the different kinds of timing residuals with the Markov Chain Monte Carlo method. Finally, we simulate the spin evolution over 20 years for a pulsar with typical parameters and analyse the data with the conventional timing solution fitting. By choosing different segments of the simulated data, we find that most of the observed residual patterns can be reproduced successfully. This is the first time that the observed residual patterns are fitted by a model and reproduced by simulations with very few parameters. From the distribution of the different residual patterns in the P-?P diagram, we argue that (1) a single magnetic field oscillation mode exists commonly in all pulsars throughout their lifetimes; (2) there may be a transition period over the lifetimes of pulsars, in which multiple magnetic field oscillation modes exist. [ABSTRACT FROM AUTHOR]

XTE J1810-189 underwent an outburst in 2008, and was observed over ~100 d by RXTE. Performing a time-resolved spectral analysis on the photospheric radius expansion burst detected on 2008 May 4, we obtain the source distance in the range 3.5-8.7 kpc for the first time. During its outburst, XTE J1810-189 did not enter into the high/soft state, and both the soft and hard colours decreased with decreasing flux. The fractional rms remained at high values (~30 per cent). The RXTE/PCA spectra for 3-25 keV can be described by an absorbed power-law component with an additional Gaussian component, and the derived photon index V increased from 1.84 ± 0.01 to 2.25 ± 0.04 when the unabsorbed X-ray luminosity at 3-25 keV dropped from 4 x 1036 to 6 x 1035 erg s-1. The relatively high flux, dense observations and broad-band spectra are strong evidence that the softening behaviour detected in the outburst of XTE J1810-189 originates from the evolution of a non-thermal component rather than the thermal component (i.e. neutron star surface emission). [ABSTRACT FROM AUTHOR]