Studies of the diffuse Galactic radio emission are interesting both for better understanding the physical conditions in our Galaxy and for minimising the contamination in cosmological measurements .
Motivated by this we present Cosmic Background Imager 31 GHz observations of the Galactic regions NGC 6357 , NGC 6334 , W51 and W40 at \sim 4 \aas@@fstack { \prime } 5 resolution and conduct an investigation of the spectral emission process in the regions at 4 \aas@@fstack { \prime } 5 and 1 ^ { \circ } resolution .
We find that most of the emission in the regions is due to optically thin free-free .
For 2 sub-regions of NGC 6334 and for a sub-region of W51 though , at 4 \aas@@fstack { \prime } 5 resolution and at 31 GHz we detect less emission than expected from extrapolation of radio data at lower frequencies assuming a spectral index of - 0.12 for optically thin free-free emission , at 3.3 \sigma , 3.7 \sigma and 6.5 \sigma respectively .
We also detect excess emission in a sub-region of NCG 6334 at 6.4 \sigma , after ruling out any possible contribution from Ultra Compact HII ( UCHII ) regions .
At 1 ^ { \circ } resolution we detect a spinning dust component in the Spectral Energy Distribution ( SED ) of W40 that accounts for 18 \pm 7 % of the total flux density in the region at the peak frequency of 37 GHz .
Comparison with 100 { \mu m } data indicate an average dust emissivity for the sub-regions of 0.5 \pm 4.4 \mu K ( MJy sr ^ { -1 } ) ^ { -1 } .
Finally we translate the excess emission in the regions to an Anomalous Microwave Emission ( AME ) emissivity relative to the optical depth at 250 { \mu m } .
We find that this form of emissivity is independent of the AME significance and has a value somewhere in the order of 10 ^ { 4 } Jy .