1 INTRODUCTION

2 SAMPLE AND OBSERVATIONS  
2.1 Sample selection  
2.2 JCMT observations  
2.3 Archival data  

3 RESULTS  
3.1 Determining the source extents and properties from the HCO⁺ and H¹³CO⁺ emission  
3.2 Detecting active outflow signatures with SiO  
3.3 Infall signatures determined from the HCO⁺ and H¹³CO⁺ emission  
3.4 Far-IR associations  

4 DISCUSSION  
4.1 Comparison of SiO-detected and non-detected source properties  
4.2 SiO luminosity as a function of source properties  
4.3 SiO luminosity with source evolution  

5 CONCLUSIONS