diff --git a/stim/biomodels/nwt_format.pptx b/stim/biomodels/nwt_format.pptx
new file mode 100644
index 0000000..4bc8308
Binary files /dev/null and b/stim/biomodels/nwt_format.pptx differ
diff --git a/stim/math/random.h b/stim/math/random.h
index b79c31d..6643936 100644
--- a/stim/math/random.h
+++ b/stim/math/random.h
@@ -12,25 +12,23 @@ namespace stim{
 template<class T>
 class Random{
 protected:
-	void init(int seed = 0)
-	{
-		if(seed <= 0)
-			srand(time(NULL));
-		else if(seed > 0)
-			srand(time(seed));
-		else
-			std::cout << "Error: Unknown value: in STIM::RANDOM"  << std::endl;
+	void init() {
+		srand(time(NULL));
+	}
+
+	void init(unsigned int seed){
+		srand(seed);
 	}
 
 public:
 	/// Default Constructor
 	Random(){
-		init(-1);
+		init();
 	}
 
 	/// Constructor from a seed.
 	/// A positive seed sets, 0 or negative yeilds the 
-	Random(int seed){
+	Random(unsigned int seed){
 		init(seed);
 	}
 
--
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