Project Aghermann
-----------------

This is project Aghermann, a GTK+ program by Andrei Zavada
<johnhommer@gmail.com> designed to run Process S simulations on
Slow-Wave Activity profiles from (human) EEG recordings as outlined in
Achermann et al (1993).  In this capacity, Aghermann produces a set of
sleep homeostat parameters which can be used to describe and
differentiate individual sleepers, such as short vs long sleepers,
early vs late, etc.

Also provided are general-purpose facilities for displaying EEG and
accompanying recordings, such as EOG and EMG, saved in EDF (European
Data Format) files.  These recordings can then be conveniently scored;
scores can be imported/exported in plain ASCII.  Scoring asistance
is very rudimentry, and will likely remain so.

Various other useful features are:

* EEG signals can be manually filtered for artifacts.  The PSD
  analysis is then performed on clean epochs, greatly enhancing the
  resulting spectral power profile.  Power course profiles can be
  obtained for an arbitrary frequency range.

* 'Unfazer', a means to alleviate artifacts occurring in one channel
  impacting another, such as, EOG blinks picked up by an EEG electrode
  (implemented as simple subtraction of EOG signal from the affected
  EEG signal, times an adjustable factor).

* Butterworth Low-pass, high-pass and band-pass filters.

* Per-channel annotations, with an experiment-wide dialog for quickly
  jumping to so bookmarked episodes.

* Pattern finding.  A pattern is characterized by its low-frequency
  component (adjustable cutoff and filter order), its envelope (a pair
  of lines connecting local extrema, with adjustable 'tightness'), and
  a density function of the zerocrossings of signal derivative (with
  variable sigma and sampling interval, interpolated).  Using these
  criteria and some tuning, one can find occurrences of a pattern
  (say, a K-complex) in the signal.

* Phase difference between channels, which can hint at the direction
  of propagation of EEG waves in a certain frequency band.  It is
  determined as a shift of one signal's band-passed component against
  another such that the difference between them is minimal.  (This
  feature's usefulness is highly tentative though.)

Aghermann keeps the recordings in an organized fashion in a tree,
following an experimental design commonly used in sleep research,
i.e., groups of subjects sleeping several (timed) episoded per
session, with recordings from a number of channels.

