Postdoctoral position available dealing with nonlinear dynamics of heart pacing and respiration 
Theoretical Modeling of the Dynamics of the Pacing Systems of Heart and Respiration of Infants in Neonatal Intensive Care Units
The pacing system of the heart is complex; a healthy heart is constantly integrating and responding to external and internal signals. However, in some pathological or age-related states, one finds that the dynamics can show reduced complexity. Such events provide an early, noninvasive warning of illness, and may also provide an opportunity to understand elements of the pacing system of the human heart.
Several years ago, Dr. Randall Moorman and his colleagues began collecting data on heart rates of infants in the neonatal intensive care unit at the University of Virginia. These infants are vulnerable to a variety of bacterial, viral or fungal infections (collectively called sepsis). The diagnosis of neonatal sepsis is difficult and time-consuming, so it would be good to have a continuous noninvasive monitor.
Moorman and colleagues showed that reduced variability of the heart rate is one warning sign of possible sepsis, and more recently we developed a pattern-recognition method proving that transient slowing of the heart rate is a second warning sign. In rare cases, these transient decelerations of the heart rate occur in a regular rhythm, with a period of about 15 seconds.
We have recently shown that the transition from low variability to periodic decelerations can be modeled by a Hopf bifurcation. We are seeking physiologically based models. It is known that models of the blood-pressure to heart-rate feedback loop can display a Hopf bifurcation; we need to test whether any such model fits the observations.
Also, the heart rate is controlled locally by a collection of cells called the sino-atrial node (SAN), which constitute the natural pacemaker of the heart. The SAN is governed internally by two coupled clocks, a transmembrane oscillator, and an internal calcium oscillator. A dynamical analysis of this pair of clocks is needed.
A new project deals with neonatal apnea, or apnea of prematurity. This is the most common serious disorder of premature infants in the neonatal intensive care unit (NICU). We have begun the collection of a huge database including EKG, respiration, oxygen saturation and in some cases blood pressure. We seek signals that will give early warning of apnea, and signals that indicate that the infant is safe.
This project is purely theoretical; it involves creation of pattern recognition software, statistical analysis of data streams, and dynamical analysis of mathematical models of the heart rate and respiration.
For related information see http://web.wm.edu/physics/DelosWeb/index.php
Send applications to jbdelo@wm.edu
John B Delos
Physics Department
College of William and Mary
Williamsburg, VA, 23187-8795
The College of William and Mary is a state supported university and an EEO/AA employer.
The pacing system of the heart is complex; a healthy heart is constantly integrating and responding to external and internal signals. However, in some pathological or age-related states, one finds that the dynamics can show reduced complexity. Such events provide an early, noninvasive warning of illness, and may also provide an opportunity to understand elements of the pacing system of the human heart.
Several years ago, Dr. Randall Moorman and his colleagues began collecting data on heart rates of infants in the neonatal intensive care unit at the University of Virginia. These infants are vulnerable to a variety of bacterial, viral or fungal infections (collectively called sepsis). The diagnosis of neonatal sepsis is difficult and time-consuming, so it would be good to have a continuous noninvasive monitor.
Moorman and colleagues showed that reduced variability of the heart rate is one warning sign of possible sepsis, and more recently we developed a pattern-recognition method proving that transient slowing of the heart rate is a second warning sign. In rare cases, these transient decelerations of the heart rate occur in a regular rhythm, with a period of about 15 seconds.
We have recently shown that the transition from low variability to periodic decelerations can be modeled by a Hopf bifurcation. We are seeking physiologically based models. It is known that models of the blood-pressure to heart-rate feedback loop can display a Hopf bifurcation; we need to test whether any such model fits the observations.
Also, the heart rate is controlled locally by a collection of cells called the sino-atrial node (SAN), which constitute the natural pacemaker of the heart. The SAN is governed internally by two coupled clocks, a transmembrane oscillator, and an internal calcium oscillator. A dynamical analysis of this pair of clocks is needed.
A new project deals with neonatal apnea, or apnea of prematurity. This is the most common serious disorder of premature infants in the neonatal intensive care unit (NICU). We have begun the collection of a huge database including EKG, respiration, oxygen saturation and in some cases blood pressure. We seek signals that will give early warning of apnea, and signals that indicate that the infant is safe.
This project is purely theoretical; it involves creation of pattern recognition software, statistical analysis of data streams, and dynamical analysis of mathematical models of the heart rate and respiration.
For related information see http://web.wm.edu/physics/DelosWeb/index.php
Send applications to jbdelo@wm.edu
John B Delos
Physics Department
College of William and Mary
Williamsburg, VA, 23187-8795
The College of William and Mary is a state supported university and an EEO/AA employer.
posted 2009.09.24
