Development Of Statistical Physics Research Articles

A Perspective on Lindblad’s Non-Equilibrium Entropy

In 1983 Göran Lindblad published a monograph on nonequilibrium thermodynamics. We here summarize the contents of this book, and provide a perspective on its relation to later developments in statistical physics and quantum physics. We high-light two aspects. The first is the idea that while all unitaries can be allowed in principle, different theories result from limiting which unitary evolutions are realized in the real world. The second is that Lindblad’s proposal for thermodynamic entropy (as opposed to information-theoretic entropy) foreshadows much more recent investigations into optimal quantum transport which is a current research focus in several fields.

Statistical Physics for Medical Diagnostics: Learning, Inference, and Optimization Algorithms.

It is widely believed that cooperation between clinicians and machines may address many of the decisional fragilities intrinsic to current medical practice. However, the realization of this potential will require more precise definitions of disease states as well as their dynamics and interactions. A careful probabilistic examination of symptoms and signs, including the molecular profiles of the relevant biochemical networks, will often be required for building an unbiased and efficient diagnostic approach. Analogous problems have been studied for years by physicists extracting macroscopic states of various physical systems by examining microscopic elements and their interactions. These valuable experiences are now being extended to the medical field. From this perspective, we discuss how recent developments in statistical physics, machine learning and inference algorithms are coming together to improve current medical diagnostic approaches.

Recovery of Equilibrium Free Energy from Nonequilibrium Thermodynamics with Mechanosensitive Ion Channels in E.coli.

Insitu measurements of the free energy difference between the open and closed states of ion channels are challenging due to hysteresis effects and inactivation. Exploiting recent developments in statistical physics, we present a general formalism to extract the free energy difference ΔF between the closed and open states of mechanosensitive ion channels from nonequilibrium work distributions associated with the opening and closing of the channels (gating) in response to ramp stimulation protocols recorded in native patches. We show that the work distributions obtained from the gating of MscS channels in E.coli membrane satisfy the strong symmetry relation predicted by the Crooks fluctuation theorem. Our approach enables the determination of ΔF using patch-clamp experiments, which are often inherently restricted to the nonequilibrium regime.

Recovery of Equilibrium Free Energy from Non-Equilibrium Thermodynamics with Mechanosensitive Ion Channels in E. coli

Bacterial mechanosensitive channels are major players in cells ability to cope with hypo-osmotic stress. Excess turgor pressure due to fast water influx is reduced as the channels, triggered by membrane tension, open and release osmolytes. However, in vitro measurements of the free energy difference between the open and closed states of ion channels are challenging due to hysteresis effects and inactivation. Exploiting recent developments in statistical physics, we present a general formalism to extract the free energy difference between the closed and open states of mechanosensitive ion channels from non-equilibrium work distributions associated with the channels gating recorded in native patches under ramp stimulation protocols. We show that the work distributions obtained from the gating of MscS channels in E. coli membrane satisfy the strong symmetry relations predicted by the fluctuation theorems and recover the equilibrium free energy difference between the closed and open states of the channel within 1 k B T of its best estimate obtained from an independent experiment.

Story of the Developments in Statistical Physics of Fracture, Breakdown and Earthquake: A Personal Account

We review the developments of the statistical physics of fracture and earthquake over the last four decades. We argue that major progress has been made in this field and that the key concepts should now become integral part of the (under-) graduate level text books in condensed matter physics. For arguing in favor of this, we compare the development (citations) with the same for some other related topics in condensed matter, for which Nobel prizes have already been awarded.

About a nonadditivity of energy and entropy

The mathematical expression of nonadditivity X(1 ∪ 2) = X(1) + X(2) + αX(1)X(2) has been frequently used for the development of statistical physics for nonadditive system, where X is entropy or energy, and α is hoped to be a parameter characterising the nonadditive property of the composite system (1 ∪ 2). Here we show that this relationship cannot hold exactly. In general, α in this expression inevitably depends on how a given system with constant X(1 ∪ 2) is divided into subsystems 1 and 2. Hence mathematical problems may arise when it is used to characterise the nonadditivity of the system. Nevertheless, under some conditions, it is possible to use it as a good approximation.