diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000000000000000000000000000000000000..d1207942c644aab06278c9e4907f8b02704fb802
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+out
+*__pycache__*
\ No newline at end of file
diff --git a/README.md b/README.md
index 804b46bb66f7c1a0647ea956fa489aad73f11ff6..3154395ab10e254d5f3d6bb50ec582a7a21c50f5 100644
--- a/README.md
+++ b/README.md
@@ -14,8 +14,8 @@ We can start a small expe!
 
 On one shell:
 ```
-ns -A example-shell
-pybatsim rejector
+ns -A dev
+pybatsim newSched
 ```
 
 On the other shell:
diff --git a/default.nix b/default.nix
index 417328886df8bd20b51ed32f8ea0c9ecb79bee53..e096399aea3782a8a67352a122b01a7585762e50 100644
--- a/default.nix
+++ b/default.nix
@@ -8,7 +8,6 @@
 , python3 ? pkgs.python311
 , python3Packages ? pkgs.python311Packages
 # , pybatsim-core ? kapack.pybatsim-core
-, poetry ? pkgs.poetry
 }:
 
 let
@@ -27,9 +26,17 @@ let
     
     # small shell to dev and test schedulers
     dev = pkgs.mkShell rec {
-      buildInputs = [
-        # pkgs.stdenv.cc.cc.lib
-        poetry
+      packages = [
+        # kapack.pybatsim-core
+        pkgs.stdenv.cc.cc.lib
+        # python3Packages.poetry
+        python3
+        (pkgs.poetry.override { python3 = python3; })
+        # (python3.withPackages 
+        #   (ps: with ps; with python3Packages; [
+        #     poetry-core
+        #   ])
+        # )
       ];
       shellHook = ''
         cd sched
@@ -38,7 +45,7 @@ let
         poetry shell
       '';
 
-      # LD_LIBRARY_PATH="${pkgs.stdenv.cc.cc.lib}/lib";
+      LD_LIBRARY_PATH="${pkgs.stdenv.cc.cc.lib}/lib";
     };
 
     expe = pkgs.mkShell rec {
@@ -71,17 +78,11 @@ let
 
     test = pkgs.mkShell rec {
       buildInputs = [
-        (python3.withPackages 
-          (ps: with ps; with python3Packages; [
-            matplotlib])
-        )
+        pkgs.stdenv.cc.cc.lib
+        python3Packages.poetry-core
       ];
-      # QT_PLUGIN_PATH = with nixpkgs.libsForQt5.qt5; "${qtbase}/${qtbase.qtPluginPrefix}";
-      # QT_QPA_PLATFORM_PLUGIN_PATH=  with nixpkgs.libsForQt5.qt5; "${qtbase.bin}/lib/qt-${qtbase.version}/plugins/platforms";      
-      # shellHook = ''
-      # QT_QPA_PLATFORM_PLUGIN_PATH="${qt6.qtbase.bin}/lib/qt-${qt6.qtbase.version}/plugins/platforms";
-      # '';
-      # nativeBuildInputs = [ nixpkgs.qt6.wrapQtAppsHook ]; 
+
+      LD_LIBRARY_PATH="${pkgs.stdenv.cc.cc.lib}/lib";
     };
     # lib = pkgs.lib;
     # pybatsim-example = python3Packages.buildPythonPackage rec {
diff --git a/expe/plot.py b/util/plot.py
old mode 100644
new mode 100755
similarity index 100%
rename from expe/plot.py
rename to util/plot.py