diff --git a/2021-07-19.md b/2021-07-19.md
index e69de29bb..4593126c6 100644
--- a/2021-07-19.md
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@@ -0,0 +1,3 @@
+- [[stpa]]
+- [[japanese garden]]
+- [[magic mushrooms]]
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diff --git a/japanese garden.md b/japanese garden.md
new file mode 100644
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+- a [[space]]
+	- [[sound]] https://mynoise.net/NoiseMachines/japaneseGardenSoundscapeGenerator.php
+		- [[go]] [[sound]]
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diff --git a/magic mushrooms.md b/magic mushrooms.md
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index 000000000..3b30ab5ee
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+- a [[thing]]
+	- [[go]] https://en.wikipedia.org/wiki/Psilocybin_mushroom
+	- https://twitter.com/flancian/status/1417194313826684932
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diff --git a/system theoretic process analysis.md b/system theoretic process analysis.md
index 537679f06..fe88f63fe 100644
--- a/system theoretic process analysis.md	
+++ b/system theoretic process analysis.md	
@@ -29,5 +29,10 @@
 		- [[feedback]] can be derived from [[responsibilities]] (which information does the process model need to contain?)
 	- step three: [[identify unsafe control actions]]
 		- an [[unsafe control action]] is one that, in a particular context, will lead to a [[hazard]].
-		
+		- it must include the actual (real) context in which the control action is unsafe, instead of controller beliefs; and it must be linked to a hazard.
+		- define [[controller constraints]]: behaviours that need to be satisfied to prevent UCAs. they can usually be derived from negations of the UCAs.
+	- step four: [[identify loss scenarios]]
+		- a [[loss scenario]] describes the [[causal factors]] that can lead to the [[unsafe control actions]] and to [[hazards]].
+		- 4a: write scenarios which cause UCAs
+		- 4b: write scenarios where control actions are ont followed
 	
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