ScLi9- Identify type оf reseаrch in reseаrch аrticles The fоllоwing are excerpts of the study The application of amplicon length heterogeneity PCR (LH-PCR) for monitoring the dynamics of soil microbial communities associated with cadaver decomposition coauthored by Dr. De Etta Mills (professor in our bio department) "The use of microbial community variations of underlying grave soils has not been thoroughly studied for the determination of time and placement of a body [...] The objective of this study was to determine changes in eubacterial metagenomic composition of the soil on which bodies had been placed with respect to ‘pristine’ soils using a fast and reliable molecular method commonly used in the ecological field and applying it to potentially identify burial sites. [...] Soils were collected within the Anthropology Research Facility, the outdoor laboratory of the Forensic Anthropology Center of the University of Tennessee in Knoxville, Tennessee. Because of the very limited number of ‘new’ cadavers available for study, nine sites were sampled and soil was collected in triplicate from underneath the bodies at a maximumdepth of 2.5 cm at 1, 2, 4, 8, and 16 weeks postplacement. The donated/available cadavers used were placed on the soil between late April and early November of 2007. In addition, four control site soil samples (non grave sites) were collected during May and November of 2007 and February of 2008. The control sites were located at each of four cardinal points within the same enclosed wooded area. (to determine the bacterial community at each site) Two of the nine hypervariable domains of the 16SrRNA genes were amplified using universal eubacterial primers. The non-overlapping domains assayed were chosen based on the results from a previous study (Moreno et al., 2006) that indicated these two domains in combination provided discrete information that could discriminate between soil microbial communities." What type of study is this?