Narayanankutty Karuppath

Diffuse Radiation from the Aquila Rift

We present an analysis of the diffuse ultraviolet (UV) background in a low latitude region near the Aquila Rift based on observations made by the Galaxy Evolution Explorer (GALEX). The UV background is at a level of about 2000 ph cm^-2 s^-1 sr^-1 \AA^-1 with no correlation with either the Galactic latitude or the 100 micron infrared (IR) emission. Rather, the UV emission falls off with distance from the bright B2 star HIP 88149, which is in the centre of the field. We have used a Monte Carlo model to derive an albedo of 0.6 - 0.7 in the UV with a phase function asymmetry factor (g) of 0.2 - 0.4. The value for the albedo is dependent on the dust distribution while g is determined by the extent of the halo.

Aspects of Feynman Graphs

Abstract Points (vertices) and lines (edges) can be compared to the particles and waves in nature. Graphical, visual representations of objects and processes possess many properties which are quite advantageous and practically useful. Richard P. Feynman, made copious applications of the graph-theoretic language, ideas and methods for understanding the micro-world of elementary particles and their interactions. Here, we discus certain significant features of Feynman graphs or diagrams in the modern context. We make a novel observation that the CPT theorem is embedded in the space-time concepts of Feynman graphs and hence the success and precision of some the calculations of QED are in fact testament to the correctness and accuracy of this theorem.