# Thermal hysteresis and its physical significance in lipid membranes?

We usually associate the phenomenon of hysteresis with memory in the system. For example, magnetic hysteresis is the basis of hard disks(if I recall it correctly). There are also electronic circuits(like Schmitt trigger) which exhibit hysteresis and thus memory.

Now coming to my question. I study about lipid membranes using all-atom classical molecular dynamics(MD) simulations. Recently, I read Sun & Böckmann's 2018 paper Membrane phase transition during heating and cooling: molecular insight into reversible melting (NB: PDF), which reports replication of phase transition in-silico in lipid membranes as a variable of temperature. But the interesting thing is that the phase changes at a temperature(T1) when you increase the temperature, but while reducing the temperature you see phase transition not at T1, but at T2. This is called Thermal Hysteresis.

• My question is what kind of memory this system has?
• Can we use this phenomenon for some practical use?
• And what biological significance does this possibly imply?

It seems the system has thermal memory, it is keeping track of whether there are spikes in temperature. It switches 'on' when the temperature is greater than $$~334\,$$K, just like magnetic memory on application of magnetic field.