@TechReport{	  it:2007-012,
  author	= {Alexander Churilov and Alexander Medvedev and Alexander
		  Shepeljavyi},
  title		= {Mathematical Model of Non-Basal Testosterone Regulation in
		  the Male by Pulse Modulated Feedback},
  institution	= {Department of Information Technology, Uppsala University},
  department	= {Division of Systems and Control},
  year		= {2007},
  number	= {2007-012},
  month		= apr,
  abstract	= {A parsimonious mathematical model of pulse modulated
		  regulation of non-basal testosterone secretion in the male
		  is developed. The model is of third differential order,
		  reflecting the three most significant hormones in the
		  regulation loop, but is yet shown to be capable of
		  sustaining periodic solutions with one or two pulses of
		  gonadotropin-releasing hormone (GnRH) on each period. Lack
		  of stable periodic solutions is otherwise a main
		  shortcoming of existing low-order hormone regulation
		  models. Existence and stability of periodic solutions are
		  studied. The periodic mode with two GnRH pulses on the
		  least period has not been described in medical literature
		  but is found to explain experimental data well. }
}