diff --git a/hysop/__init__.py b/hysop/__init__.py
index c96fe188aee1bc2d4732bcc55d5ba39a411e3ef5..0501895e8d3475908dda017a9b36a709217bbd14 100644
--- a/hysop/__init__.py
+++ b/hysop/__init__.py
@@ -19,7 +19,8 @@ __OPTIMIZE__       = not __debug__
 __VERBOSE__        = True
 __DEBUG__          = False
 __TRACE__          = False
-__KERNEL_DEBUG__   = True
+__TRACE_WARNINGS_  = False
+__KERNEL_DEBUG__   = False
 __PROFILE__        = True
 
 __ENABLE_LONG_TESTS__ = False
diff --git a/hysop/__init__.py.in b/hysop/__init__.py.in
index 9d74d3d5fbf2d27b18bc438ed715042c9d72e890..c4d4acee5fd5e51a169b22aeb9e73efafd198e37 100644
--- a/hysop/__init__.py.in
+++ b/hysop/__init__.py.in
@@ -3,7 +3,7 @@ on hybrid architectures (MPI-GPU)
 
 """
 from functools import wraps
-from hysop.deps import __builtin__, print_function, os, sys
+from hysop.deps import __builtin__, print_function, os, sys, warnings, traceback
 
 # HySoP
 package_name = "@PACKAGE_NAME@"
@@ -18,9 +18,10 @@ __OPTIMIZE__       = not __debug__
 
 __VERBOSE__        = "@DEBUG@"   in ["1", "3"]
 __DEBUG__          = "@DEBUG@"   in ["2", "3"]
-__TRACE__          = "@DEBUG@"   in ["5"]
-__KERNEL_DEBUG__   = "@DEBUG@"   in ["4", "3"]
-__PROFILE__        = "@PROFILE@" in ["0", "1"]
+__TRACE__          = False
+__TRACE_WARNINGS_  = False
+__KERNEL_DEBUG__   = False
+__PROFILE__        = True
 
 __ENABLE_LONG_TESTS__ = "@ENABLE_LONG_TESTS@" is "ON"
 
@@ -28,7 +29,6 @@ __ENABLE_LONG_TESTS__ = "@ENABLE_LONG_TESTS@" is "ON"
 __DEFAULT_PLATFORM_ID__ = @OPENCL_DEFAULT_OPENCL_PLATFORM_ID@
 __DEFAULT_DEVICE_ID__   = @OPENCL_DEFAULT_OPENCL_DEVICE_ID@
 
-
 if __MPI_ENABLED__:
     from hysop.core.mpi import MPI, main_rank, main_size, \
                                host_rank, interhost_size, \
@@ -38,7 +38,6 @@ if __MPI_ENABLED__:
 def print(*args, **kargs):
     """Wrap print function (because of python 3)"""
     __builtin__.print(*args, **kargs)
-
 def vprint(*args, **kargs):
     """prints only if __VERBOSE__ has been set"""
     if __VERBOSE__:
@@ -60,11 +59,17 @@ def sprint(*args, **kargs):
     """prints only shared memory master rank 0"""
     if (shm_rank==0):
         vprint(*args, **kargs)
-                values=transposition_states[len(candidate_axes.dd
+        
+def reset():
+    """Reset hysop state (registered objects)."""
+    from hysop.tools.handle import RegisteredObject
+    RegisteredObject._RegisteredObject__reset()
 
 # override warning printer
 __formatwarning = warnings.formatwarning
-def __new_formatwarning(message, category, filename, lineno, line=none):
+def __new_formatwarning(message, category, filename, lineno, line=None):
+    if __TRACE_WARNINGS__:
+        traceback.print_stack()
     return __formatwarning(message, category, filename, lineno, line='')
 warnings.formatwarning = __new_formatwarning
 
@@ -75,16 +80,16 @@ if __TRACE__:
 
 from hysop.domain.domain      import Domain
 from hysop.domain.box         import Box
-from hysop.fields.continuous  import Field
-from hysop.fields.discrete    import DiscreteField
-from hysop.core.mpi.cartesian import Topology, Cartesian
-from hysop.core.mpi.topology_descriptor  import TopologyDescriptor
+from hysop.fields.continuous_field  import Field
+from hysop.fields.discrete_field    import DiscreteField
+from hysop.topology.cartesian_topology import Topology, CartesianTopology
+from hysop.topology.topology_descriptor  import TopologyDescriptor
 from hysop.tools.parameters   import Discretization
 from hysop.simulation         import Simulation
 from hysop.problem            import Problem
 from hysop.tools.io_utils     import IO, IOParams
 __all__ = ['Box', 'Field', 'DiscreteField', 'Domain', 'Discretization', 'Simulation', 
-           'Problem', 'IO', 'IOParams', 'Topology', 'Cartesian', 'TopologyDescriptor']
+           'Problem', 'IO', 'IOParams', 'Topology', 'CartesianTopology', 'TopologyDescriptor']
 if __MPI_ENABLED__:
     __all__ += ['MPI', 'main_rank', 'main_size']
 
@@ -107,6 +112,5 @@ default_path = IO.default_path()
 cache_path   = IO.default_cache_path()
 msg_io =  '\n*Default path for all i/o is \'{}\'.'.format(default_path)
 msg_io += '\n*Default path for caching is \'{}\'.'.format(cache_path)
-msg_io += '\n'
 vprint(msg_io)