Update heterogeneity.md

doc/heterogeneity.md

@@ -13,7 +13,7 @@ The PDB structure of the complex informs the final state of our model and constr
 
 # Heterogeneity modeling step 2: representation, scoring function, and search process {#heterogeneity2}
 
-Next, we represent, score and search for heterogeneity models models. These operations are performed by the `heterogeneity_modeling.py` in the `Heterogeneity/Heterogeneity_Modeling` folder. As ET and SAXS data, are only available at 0 minutes, 1 minute, and 2 minutes, we choose to create heterogeneity models at these three time points. We know this complex has three protein chains (A, B, and C), and we choose to model these chains based on their protein copy number data. We then use `prepare_protein_library`, [documented here](https://integrativemodeling.org/nightly/doc/ref/namespaceIMP_1_1spatiotemporal_1_1prepare__protein__library.html), to calculate the protein copy numbers for each snapshot model and to use the topology file of the full complex (`spatiotemporal_topology.txt`) to generate a topology file for each of these snapshot models. The choices made in this topology file are important for the representation, scoring function, and search process for snapshot models, and are [discussed later.] (@ref snapshot_representation) For heterogeneity modeling, we choose to model 3 protein copy numbers at each time point, and restrict the final time point to have the same protein copy numbers as the PDB structure. 
+Next, we represent, score and search for heterogeneity models models. These operations are performed by the `heterogeneity_modeling.py` in the `Heterogeneity/Heterogeneity_Modeling` folder. A single heterogeneity model is a set of protein copy numbers, scored according to its fit to experimental copy number data at that time point. As ET and SAXS data, are only available at 0 minutes, 1 minute, and 2 minutes, we choose to create heterogeneity models at these three time points. We then use `prepare_protein_library`, [documented here](https://integrativemodeling.org/nightly/doc/ref/namespaceIMP_1_1spatiotemporal_1_1prepare__protein__library.html), to calculate the protein copy numbers for each snapshot model and to use the topology file of the full complex (`spatiotemporal_topology.txt`) to generate a topology file for each of these snapshot models. The choices made in this topology file are important for the representation, scoring function, and search process for snapshot models, and are [discussed later.] (@ref snapshot_representation) For heterogeneity modeling, we choose to model 3 protein copy numbers at each time point, and restrict the final time point to have the same protein copy numbers as the PDB structure. 
 
 \code{.py}
 # 1a - parameters for prepare_protein_library: