7 research outputs found
Intermittency as metastability: a predictive approach to evolution in disordered environments
Many systems across the sciences evolve through a combination of
multiplicative growth and diffusive transport. In the presence of disorder,
these systems tend to form localized structures which alternate between long
periods of relative stasis and short bursts of activity. This behaviour, known
as intermittency in physics and punctuated equilibrium in evolutionary theory,
is difficult to forecast; in particular there is no general principle to locate
the regions where the system will settle, how long it will stay there, or where
it will jump next. Here I introduce a predictive theory of linear intermittency
that closes these gaps. I show that any positive linear system can be mapped
onto a generalization of the "maximal entropy random walk", a Markov process on
graphs with non-local transition rates. This construction reveals the
localization islands as local minima of an effective potential, and
intermittent jumps as barrier crossings in that potential. My results unify the
concepts of intermittency in linear systems and Markovian metastability, and
provide a generally applicable method to reduce, and predict, the dynamics of
disordered linear systems. Applications span physics, evolutionary dynamics and
epidemiology.Comment: Extension of arXiv:1912.0589
On the Use of Coarse-Grained Thermodynamic Landscapes to Efficiently Estimate Folding Kinetics for RNA Molecules
Thesis advisor: Peter CloteRNA folding pathways play an important role in various biological processes, such as 1) the conformational switch in spliced leader RNA from Leptomonas collosoma, which controls transsplicing of a portion of the 5’ exon, and 2) riboswitches–portions of the 5’ untranslated region of mRNA that regulate genes by allostery. Since RNA folding pathways are determined by the thermodynamic landscape, we have developed a number of novel algorithms—including FFTbor and FFTbor2D—which efficiently compute the coarse-grained energy landscape for a given RNA sequence. These energy landscapes can then be used to produce a model for RNA folding kinetics that can compute both the mean first passage time (MFPT) and equilibrium time in a deterministic and efficient manner, using a new software package we call Hermes. The speed of the software provided within Hermes—namely FFTmfpt and FFTeq—present what we believe to be the first suite of kinetic analysis tools for RNA sequences that are suitable for high throughput usage, something we believe to be of interest in the field of synthetic design.Thesis (PhD) — Boston College, 2015.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Biology