arXiv subjects

Tomohiro Tanogami

Publications and source records attributed to Tomohiro Tanogami.

12 recordsLinked to original sources

arXiv2026

Energy Conversion, Fluctuation Suppression, and Information Transfer in the Thermodynamic Performance of Kinesin

Kinesin is a molecular motor that transports intracellular cargoes along microtubules. Recent studies have quantified kinesin performance using various efficiencies within the framework of stochastic thermodynamics; however, quantitative comparisons remain difficult because different models and assumptions have been employed. As a result, it remains unclear which aspect of kinesin performance, if any, is thermodynamically optimized. Here, we systematically compare multiple thermodynamic efficiencies within a single kinesin-cargo model. To this end, we construct a thermodynamically consistent two-state kinesin-cargo model that retains both the discrete stepping of kinesin and its coupling to the cargo. Assuming a separation of time scales between the motor and the cargo, we derive analytical expressions for the thermodynamic efficiency, the information-thermodynamic efficiency, the thermodynamic uncertainty relation (TUR) efficiency, and the bipartite TUR efficiency, and compare them with numerical simulation results. We find that these efficiencies generally remain low, suggesting that kinesin is not optimized for maximizing the thermodynamic efficiencies considered here. Our results suggest that thermodynamic efficiencies alone may not fully characterize kinesin performance and motivate further investigation of complementary kinetic perspectives for assessing molecular motor function.

cond-mat.stat-mech↗

arXiv2025

Scale locality of information flow in shell models of turbulence

Turbulent fluctuations exhibit universal scaling laws that are independent of large-scale statistics. It is often explained that such universality is caused by the loss of information about large-scale statistics during the cascade process. In our previous study [T. Tanogami and R. Araki, Phys. Rev. Research 6, 013090 (2024)], we applied information thermodynamics to turbulence and proved that information of large-scale turbulent fluctuations is propagated to small scales. As a first step toward understanding how universality emerges at small scales under the influence of the information flow from large scales, here we investigate the scale locality of the information flow for shell models. First, we analytically show that the information flow can be decomposed into scale-local and scale-nonlocal parts. Then, by assuming the Kolmogorov hypothesis for the Kolmogorov multiplier, we prove that the scale-nonlocal part can be ignored compared to the scale-local part. This result implies that the information transfer from large to small scales occurs mainly through scale-local interactions, which is consistent with the scale locality of the energy cascade.

cond-mat.stat-mech↗

arXiv2025

Information Propagation in Predator-Prey Dynamics of Turbulent Plasma

Magnetically confined fusion plasmas exhibit predator-prey-like cyclic oscillations through the self-regulating interaction between drift-wave turbulence and zonal flow. To elucidate the detailed mechanism and causality underlying this phenomenon, we construct a simple stochastic predator-prey model that incorporates intrinsic fluctuations and analyze its statistical properties from an information-theoretic perspective. We first show that the model exhibits persistent fluctuating cyclic oscillations called quasi-cycles due to amplification of intrinsic noise. This result suggests the possibility that the previously observed periodic oscillations in a toroidal plasma are not limit cycles but quasi-cycles, and that such quasi-cycles may be widely observed under various conditions. For this model, we further prove that information of the zonal flow is propagated to turbulence. This result suggests that turbulence behavior may be predictable to a certain extent based on zonal flow characteristics.

physics.plasm-ph↗

arXiv2024

Scale-to-Scale Information Flow Amplifies Turbulent Fluctuations

In three-dimensional turbulence, information of turbulent fluctuations at large scales is propagated to small scales. Here, we investigate the relation between the information flow and turbulent fluctuations described by a shell model. We first establish a connection between the information flow and phase-space contraction rate. From this relation, we then prove an inequality between the information flow and turbulent fluctuations, which suggests that the information flow from large to small scales amplifies turbulent fluctuations at small scales. This inequality can also be interpreted as a quantification of Landau's objection to the universality of turbulent fluctuations. We also discuss differences between the information flow and the Kolmogorov-Sinai entropy.

cond-mat.stat-mech↗

arXiv2023

Universal bounds on the performance of information-thermodynamic engine

We investigate fundamental limits on the performance of information processing systems from the perspective of information thermodynamics. We first extend the thermodynamic uncertainty relation (TUR) to a subsystem. Specifically, for a bipartite composite system consisting of a system of interest X and an auxiliary system Y, we show that the relative fluctuation of an arbitrary current for X is lower bounded not only by the entropy production associated with X but also by the information flow between X and Y. As a direct consequence of this bipartite TUR, we prove universal trade-off relations between the output power and efficiency of an information-thermodynamic engine in the fast relaxation limit of the auxiliary system. In this limit, we further show that the Gallavotti-Cohen symmetry is satisfied even in the presence of information flow. This symmetry leads to universal relations between the fluctuations of information flow and entropy production in the linear response regime. We illustrate these results with simple examples: coupled quantum dots and coupled linear overdamped Langevin equations. Interestingly, in the latter case, the equality of the bipartite TUR is achieved even far from equilibrium, which is a very different property from the standard TUR. Our results will be applicable to a wide range of systems, including biological systems, and thus provide insight into the design principles of biological systems.

cond-mat.stat-mech↗

arXiv2023

Information-Thermodynamic Bound on Information Flow in Turbulent Cascade

We investigate the nature of information flow in turbulence from an information-thermodynamic viewpoint. For the fully developed three-dimensional fluid turbulence described by the fluctuating Navier-Stokes equation, we prove that information of large-scale eddies is transferred to small scales along with the energy cascade. We numerically illustrate our findings using a shell model and further show that in the inertial range, the intensity of the information flow is nearly constant and can be scaled by the large-eddy turnover time. Our numerical results also suggest that the corresponding information-thermodynamic efficiency is quite low compared to other typical information processing systems such as Maxwell's demon. These findings provide a new perspective on how universality and intermittency of turbulent fluctuations emerge at small scales.

cond-mat.stat-mech↗

arXiv2022

A Simple XY Model for Cascade Transfer

We propose a modified XY model in which cascade transfer emerges from spatially local interactions, where the spin corresponds to the "velocity" of a turbulent field. For this model, we theoretically calculate the scale-to-scale energy flux and the equal time correlation function in $d$ dimensions. The result indicates an inverse energy cascade with the non-Kolmogorov energy spectrum proportional to $k^{-3}$. We also numerically confirm the result for the cases $d=2$ and $d=3$. We thus conclude that the cascade transfer in our model represents a different universality class from standard fluid turbulence.

cond-mat.stat-mech↗

arXiv2022

Violation of the second fluctuation-dissipation relation and entropy production in nonequilibrium medium

We investigate a class of nonequilibrium media described by Langevin dynamics that satisfies the local detailed balance. For the effective dynamics of a probe immersed in the medium, we derive an inequality that bounds the violation of the second fluctuation-dissipation relation (FDR). We also discuss the validity of the effective dynamics. In particular, we show that the effective dynamics obtained from nonequilibrium linear response theory is consistent with that obtained from a singular perturbation method. As an example of these results, we propose a simple model for a nonequilibrium medium in which the particles are subjected to potentials that switch stochastically. For this model, we show that the second FDR is recovered in the fast switching limit, although the particles are out of equilibrium.

cond-mat.stat-mech↗

arXiv2021

Reply to "Comment on 'Theoretical analysis of quantum turbulence using the Onsager ideal turbulence theory'"

We refute the criticism expressed in a Comment by Krstulovic, L'vov, and Nazarenko [arXiv:2107.10598] on our paper [Phys. Rev. E 103, 023106 (2021)]. We first show that quantization of circulation is not ignored in our analysis. Then, we propose a more sophisticated analysis to avoid a subtle problem with the regularity of the velocity field. We thus defend the main results of our paper, which predicts the double-cascade scenario where the quantum stress cascade follows the Richardson cascade. We also provide a conjecture on the relation between the Kelvin-wave cascade and the quantum stress cascade.

physics.flu-dyn↗

arXiv2021

Van der Waals Cascade in Supercritical Turbulence near a Critical Point

We investigate a quite strong turbulence in a supercritical fluid near a gas-liquid critical point. Specifically, we consider a case in which the Kolmogorov scale is much smaller than the equilibrium correlation length $ξ$. Although equilibrium critical fluctuations are destroyed by turbulence, $ξ$ still provides a crossover length scale between two types of energy cascade. At scales much larger than $ξ$, the Richardson cascade becomes dominant, whereas at scales much smaller than $ξ$, another type of cascade, which we call the van der Waals cascade, is induced by density fluctuations. Experimental conditions required to observe the van der Waals cascade are also discussed.

physics.flu-dyn↗

arXiv2021

Theoretical analysis of quantum turbulence using the Onsager "ideal turbulence" theory

We investigate three-dimensional quantum turbulence as described by the Gross-Pitaevskii model using the analytical method exploited in the Onsager "ideal turbulence" theory. We derive the scale-independence of the scale-to-scale kinetic energy flux and establish a double-cascade scenario: at scales much larger than the mean intervortex $\ell_i$, the Richardson cascade becomes dominant, whereas at scales much smaller than $\ell_i$, another type of cascade is induced by quantum stress. We then evaluate the corresponding velocity power spectrum using a phenomenological argument. The relation between the novel cascade, which we call quantum stress cascade, and the Kelvin-wave cascade is also discussed.

physics.flu-dyn↗

arXiv2019

Linear stability analysis of self-gravitating granular gas

The linear stability of granular gas that reflects the contribution of self-gravitational force of mass density perturbations is investigated in order to clarify the condition of competition between clustering instability and Jeans instability. It is found that the condition depends on three parameters: the mass density $ρ_0$, the collision rate $ω_0$, and the rate of energy loss per collision $ε$. When $\sqrt{Gρ_0}\llεω_0$, clustering instability dominates, while when $εω_0\ll\sqrt{Gρ_0}$, Jeans instability dominates. These instabilities are characterized by the decrease and increase, respectively, of the temperature.

cond-mat.stat-mech↗