Evidence for Centrifugal Barrier in X-ray Pulsar GRO J1744-28

We present further observational evidence of the effects of a centrifugal barrier in GRO J1744-28, based on continued monitoring of the source with RXTE. For X-ray pulsars, the centrifugal barrier manifests itself in the cessation of pulsed emission when the source becomes faint. We show that such phenomenon occurred repeatedly for GRO J1744-28, following the decay of two X-ray outbursts. This has allowed a direct measurement of the dipole field strength for this pulsar. Here we argue that some of the other peculiar properties observed of this source may also be related to an active centrifugal barrier.Comment: 4 pages. To appear in "Accretion Processes in Astrophysical Systems", Proc. of the 8th Annual Astrophysics Conference in Maryland, S. S. Holt & T. Kallman (eds.

Evolution of the discrete transform using genetic programming : a thesis presented in partial fulfilment of the requirements for the degree of Master in Computer Science at Massey University, Albany

Image compression is an important method in image transmission, storage and manipulation. There are many successful techniques which have been developed. Most of these methods are based on some type of rule based algorithm. The cosine transform plays a very important role in image compression. It is a standard transform used by the widely used JPEG standard. Through the use of genetic programming, we successfully evolved a programmatic cosine transform based on genetic programming. The cosine transform has been heavily researched and many efficient methods have been determined and successfully applied in practice. Here, we only suggest 'another' method to do the same work. Due to the limited power of our resources, we restricted our work to a 4 point cosine transform. As a result, an approximation to the transform is evolved by the genetic programming paradigm. In theory, the 8 point cosine transform can be evolved using a similar technique