Lecture 13 ECEN 4341/5341 February 15,2017

Assignment 1. Finish reading Chapter 5 2. One additional paper on material related to chapter 5. One paper on something toward your midterm paper which should be in the range of 5 to 10 pages on a topic you really want to know more about. Due March 6. Exam 1 February 27.

Electronic Amplifiers 1 Basic Amplifier use energy from one source and use it to increase the strength of the desired signal. 2. Electronics we take energy of a DC power supply and use it to increase the amplitude of the desired signal. 3. This is not essential we can get our energy from an AC signal in a parametric amplifier or from noise in stochastic resonate amplifier

Biological Amplifiers 1. Many kinds of amplifiers and many steps 2. Start with solar energy and photosynthesis a two step quantum process to convert CO2 N2, H2O, O2 and other atoms in to hydrocarbons. 3. Many steps to carry this through glucose to ATP to moving your arms and legs or activating your brain.

Biological Amplifiers 1 Membrane Potentials used to transmit Electro Chemical Signals. 2. More than 3000 signaling proteins and 15 second messengers. 3.Most biological amplifiers contain negative feedback to stabilize the system.

Examples 1. Nerve Cells may some the input from may dendrites to fire a synaptic junction to raise the input voltage by 10 to 20mV and this fires an action potential of 50 to 100mV. 2. Sub-threshold inputs can lead to the release of neural transmitters that, in turn, can release from 2 to 10,000 Ca2+ ions from internal stores. 3. There are more than 40 different neural transmitters such as acetylcholine (Ach).

Examples 1. Negative feedback on temperature control is about a factor of -33 2. Gain for controlling arterial blood pressure is -2. 3. There are time delays in these feedback systems. 4. Wound Healing, Hand to Eye Coordination

Operational Amplifier with Time Delay in the Feedback

Steady State Solution for Vs= Vin cos(ωt) and Vo cos (ωt –θ) where θ=ωτ, = Note change in sign with θ=ωτ so we can get either amplification or attenuation by changing frequency or the time delay τ

Oscillation The system breaks into oscillation when the gain As the gain Af oscillates from zero to

NADPH, ROS, NOS Oscillations NAD(P)H concentration in motile neutrophils is oscillatory, and the amplitude of the oscillation can resonate in the sense that the amplitude increases with externally applied pulsed magnetic fields. NAD(P)H autofluorescence was monitored with a photomultiplier, and photomultiplier counts plotted . Note the amplitude of the signal returns to its normal value when the stimulus is removed. Rosenpire et.al (2005) Figure 2.

Redox Oscillation Reduction Figure 3. Flavoprotein redox oscillations are inhibited by pulsed magnetic fields timed to coincide with minimal flavoprotein autofluorescence and they amplify the oscillations when timed at the minimums. Rosenpire et.al (2005) Figure 11.

Self Limiting Protein Synthesis Suppose that the rate of protein synthesis at present (at time t) depends on the concentration of protein at some time in the past (at time t-τ), where τ is the time delay required for transcription and translation. Then, the governing kinetic equation becomes (2) Béla Novak* and John J. Tyson ” Design Principles of Biochemical Oscillators Nat Rev Mol Cell Biol. 2008 December ; 9(12): 981–991. doi:10.1038/nrm2530.