1 INTRODUCTION  
2 OBSERVATIONS AND DATA ANALYSIS  
2.1 GBT K-band Mapping Observations  
2.2 Source Extraction and Structure Analyses  
2.3 Ammonia Spectral Line Analysis  
2.4 Beam Filling Factor  
2.5 Ammonia Column Density and Abundance  
2.6 Uncertainties on the Fitted Parameters  
3 RESULTS  
3.1 Detection Statistics  
3.2 RMS Associations  
3.3 Mid-infrared Imaging  
3.4 General Properties of the Sample  
3.5 Deriving Physical Properties  
4 DISCUSSION  
4.1 Correlation Between Physical Parameters  
5 SUMMARY AND CONCLUSIONS