arXiv subjects

Yasuji Sawada

Publications and source records attributed to Yasuji Sawada.

10 recordsLinked to original sources

arXiv2026

External Entropy Production and Human Evolution toward Multi-body Life

Ancient human beings started "external entropy production" in a late stage of evolution, in addition to the internal entropy production by which energy was dissipated within the body of life, as previously described consistently with the birth of life by maximum entropy production principle. In this paper, the mechanism for development of external entropy production, which is strongly related with use of tools and controlling fire, is theoretically investigated. Archaeological data show that the brain size of ancient human beings started rapid increase around 2.5 million years ago when the usage of tools and control of fire started. It may be natural to assume that the rapid growth of brain size is related to the growth of awareness which helped cooperation with the other human beings for control of fire. Coupled equations for the growth rate of brain including awareness and for growth rate of size of the interacting human beings are analyzed. The external entropy production per one human being which is directly related to the group size of cooperating human beings is estimated to increase as about 20 million years in the beginning from the critical time. This evolution created coexistence of internal entropy production of traditional multi-cellular life and new external entropy production of multi-body life. A psychological problem due to the coexistence of two kinds of entropy production mechanism in human being and concept of technologies based on the present thermodynamic evolution theory are discussed. It is suggested that the evolutionary understanding of the origin of global warming based on the external entropy production may be important to create an useful countermeasure.

physics.bio-ph↗

arXiv2025

Maximum Entropy Production Principle of Thermodynamics for the Birth and Evolution of Life

Research on the birth and evolution of life are reviewed with reference to the maximum entropy production principle (MEPP). It has been shown that this principle is essential for consistent understanding of the birth and evolution of life. First, a recent work for the birth of a self-replicative system as pre-RNA life is reviewed in relation to the MEPP. A critical condition of polymer concentration in a local system is reported by a dynamical system approach, above which, an exponential increase of entropy production is guaranteed. Secondly, research works of early stage of evolutions are reviewed; experimental research for the numbers of cells necessary for forming a multi-cellular organization, and numerical research of differentiation of a model system and its relation with MEPP. It is suggested by this review article that the late stage of evolution is characterized by formation of society and external entropy production. A hypothesis on the general route of evolution is discussed from the birth to the present life which follows the MEPP. Some examples of life which happened to face poor thermodynamic condition are presented with thermodynamic discussion. It is observed through this review that MEPP is consistently useful for thermodynamic understanding of birth and evolution of life, subject to a thermodynamic condition far from equilibrium.

physics.bio-ph↗

arXiv2023

An onset model of mutually catalytic self-replicative systems formed by an assembly of polynucleotides

Self-replicability is the unique attribute observed in all the living organisms and the question how the life was physically initiated could be equivalent to the question how self-replicating informative polymers were formed in the abiotic material world. It has been suggested that the present DNA and proteins world was preceded by RNA world in which genetic information of RNA molecules was replicated by the mutual catalytic function of RNA molecules. However, the important question how the transition occurred from a material world to the very early pre-RNA world remains unsolved experimentally nor theoretically. We present an onset model of mutually catalytic self-replicative systems formed in an assembly of polynucleotides. A quantitative expression of the critical condition for the onset of growing fluctuation towards self-replication in this model is obtained by analytical and numerical calculations.

physics.bio-ph↗

arXiv2020

A Thermodynamic Approach towards the Question "What is Cellular Life?"

The question "What is life?" has been asked and studied by the researchers of various fields. Nevertheless, no global theory which unified various aspects of life has been proposed so far. Considering that the physical principle for the theory of birth should be the one known for the unanimated world, and that the life processes are irreversibly selective, we showed by a deductive inference that the maximum entropy production principle plays an essential role for the birth and the evolution of life in a fertile environment. In order to explain the survival strategy of life in a barren period of environment, we also proposed that life had simultaneously developed a reversible on and off switching mechanism of the chemical reactions by the dynamics of equilibrium thermodynamics. Thus, the birth and evolution of life have been achieved by the cooperation between the driving force due to the non-equilibrium thermodynamics and the protective force due to the equilibrium thermodynamics in the alternating environmental conditions.

physics.bio-ph↗

arXiv2014

On the conflict between precision and robustness in the proportion regulation of cell types

In Dictyostelium discoideum the proportion of cell types is known to be actively regulated, recovering, for example, after the removal of a given cell type. However, we have recently shown that regulation is intrinsically imprecise: it controls the proportion above/below certain upper and lower thresholds, but not within an allowed range of values that these thresholds define. To explain this finding we present a model based on (i) a global negative feedback, and (ii) a cell-autonomous positive feedback leading to a hysteresis-like behaviour (i.e, a bistability of cell type). The simulated cell-type proportion is indeed found to span a range of values as a consequence of the bistability. We conclude that there is a general conflict between the precision of proportion regulation and the robustness of the differentiation of cell types.

physics.bio-ph↗

arXiv2000

Power law fluctuation generator based on analog electrical circuit

We constructed an analog circuit generating fluctuations of which a probability density function has power law tails. In the circuit fluctuations with an arbitrary exponent of the power law can be obtained by tuning the resistance. A theory of a differential equation with both multiplicative and additive noises which describes the circuit is introduced. The circuit is composed of a noise generator, an analog multiplier and an integral circuit. Sequential outputs of the circuit are observed and their probability density function and autocorrelation coefficients are shown. It is found that correlation time of the autocorrelation coefficient is dependent on the power law exponent.

cond-mat.stat-mech↗

arXiv1996

Effect of Chaotic Noise on Multistable Systems

In a recent letter [Phys.Rev.Lett. {\bf 30}, 3269 (1995), chao-dyn/9510011], we reported that a macroscopic chaotic determinism emerges in a multistable system: the unidirectional motion of a dissipative particle subject to an apparently symmetric chaotic noise occurs even if the particle is in a spatially symmetric potential. In this paper, we study the global dynamics of a dissipative particle by investigating the barrier crossing probability of the particle between two basins of the multistable potential. We derive analytically an expression of the barrier crossing probability of the particle subject to a chaotic noise generated by a general piecewise linear map. We also show that the obtained analytical barrier crossing probability is applicable to a chaotic noise generated not only by a piecewise linear map with a uniform invariant density but also by a non-piecewise linear map with non-uniform invariant density. We claim, from the viewpoint of the noise induced motion in a multistable system, that chaotic noise is a first realization of the effect of {\em dynamical asymmetry} of general noise which induces the symmetry breaking dynamics.

chao-dyn↗

arXiv1996

Effect of time-correlation of input patterns on the convergence of on-line learning

We studied the effects of time correlation of subsequent patterns on the convergence of on-line learning by a feedforward neural network with backpropagation algorithm. By using chaotic time series as sequences of correlated patterns, we found that the unexpected scaling of converging time with learning parameter emerges when time-correlated patterns accelerate learning process.

adap-org↗

arXiv1995

Comment on "White-Noise-Induced Transport in Periodic Structures"

In the paper by J.Łuczka {\em et al.} ({\em Europhys. Lett.}, {\bf 31} (1995) 431), the authors reported by rigorous calculation that an additive Poissonian white shot noise can induce a macroscopic current of a dissipative particle in a periodic potential -- even {\em in the absence} of spatial asymmetry of the potential. We argue that their main result is an obvious one caused by the spatially broken symmetry of a probability distribution of the additive noise, unlike the similar result caused by chaotic noise which has a symmetric probability distribution ({\em J.Phys.Soc.Jpn.}, {\bf 63} (1994) 2014).

adap-org↗

arXiv1995

Dynamical behavior of a dissipative particle in a periodic potential subject to chaotic noise: Retrieval of chaotic determinism with broken parity

Dynamical behaviors of a dissipative particle in a periodic potential subject to chaotic noise are reported. We discovered a macroscopic symmetry breaking effect of chaotic noise on a dissipative particle in a multi-stable systems emerging, even when the noise has a uniform invariant density with parity symmetry and white Fourier spectrum. The broken parity symmetry of the multi-stable potential is not necessary for the dynamics with broken symmetry. We explain the mechanism of the symmetry breaking and estimate the average velocity of a particle under chaotic noise in terms of unstable fixed points.

chao-dyn↗