Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session B46: Invited Session: Thermodynamics and Information Processing in Biochemical Networks |
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Sponsoring Units: DBIO Room: 217A |
Monday, March 2, 2015 11:15AM - 11:51AM |
B46.00001: Quantifying the Flow of Information Between Interacting Systems Invited Speaker: Christopher Jarzynski Physical systems, including biological organisms, are capable of gathering information about their surroundings and acting in response to that information. When two physical systems interact with one another, each one affects and is affected by the other. It is often convenient to view such interactions in the context of measurement and feedback, with one system observing and exercising control over the other. I will discuss fundamental limits that thermodynamics places on such processes, when the systems are small and thermal fluctuations play an important role. [Preview Abstract] |
Monday, March 2, 2015 11:51AM - 12:27PM |
B46.00002: Phosphorylation Hypothesis: A Fourth Sink of ATP for Cellular Information Processing? Invited Speaker: Hong Qian Adenosine triphosphate (ATP) molecule is used in living cells as a universal ``energy currency.'' The Gibbs free energy liberated from hydrolysis reaction of ATP to ADP $+$ Pi is used for (a) biosynthesis, (b) ionic and neutral molecular pumping, and (c) mechanical movement. They are known collectively as the three major energy sinks at the cellular level. Using biochemical activities of various enzymes, a cell carries out information processing, known as signal transduction. Essentially all signal transduction reactions also require ATP (or GTP) hydrolysis. In the past, such energy dissipative reactions are considered as ``futile.'' However, it is clear that the free energy derived from a futile cycle is used to correct errors in biomolecular recognition, improve robustness in cell development, overcome Boltzmann's equilibrium law of probability, and drive Maxwell's demons (one notes that Gibbs' chemical potential is a thermodynamic force without mechanical interpretation). The free energy involved in processing information will be explained in terms of stochastic entropy production --- the central concept in irreversible and nonequilibrium steady-state (NESS) thermodynamics. [Preview Abstract] |
Monday, March 2, 2015 12:27PM - 1:03PM |
B46.00003: A synthetic playground for non-equilibrium error correction and information processing Invited Speaker: Arvind Murugan Biological proofreading mechanisms can lower error rates well below Boltzmann statistics by consuming free energy. By abstracting the principles behind these biochemical mechanisms, we discuss the central ingredients needed for any complex reaction network to perform error correction and the inherent energy-error tradeoffs. We propose that such abstract principles can be implemented and tested in synthetic systems using DNA strand displacement reactions. Such DNA circuits can mimic biochemical models of proofreading because of two central features: 1. exquisite control over reaction kinetics, 2. a DNA analog of ATP hydrolysis. Indeed, such DNA circuits may be used to mimic any non-equilibrium information processing scheme seen in biochemistry, such as adaption and ultra-sensitivity in addition to error correction. We discuss the conceptual and practical benefits from having a well-controlled synthetic playground for non-equilibrium ideas. [Preview Abstract] |
Monday, March 2, 2015 1:03PM - 1:39PM |
B46.00004: Experimental Demonstration of Information-to-Energy Conversion in Small Fluctuating Systems Invited Speaker: Masaki Sano What is the relation between information and thermodynamics has been a long standing question in science. In 1867, J.C. Maxwell proposed a Gedanken experiment to demonstrate violation of the second law of thermodynamics by assuming a small creature called Maxwell's demon which separates hot atoms from cold atoms. In 1929, L. Szilard formulated the idea of Maxwell for a more tractable setup in which a single particle is thermally moving in a box immersed in a heat bath. He succeeded to relate information entropy and the second law of thermodynamics in this Gedanken experiment. It had led to long and intense debates on the relation among thermodynamics, information, observation, and even computation until it was clarified recently. Nevertheless, experimental realization of information-energy-conversion has been elusive. Recently, we succeeded to demonstrate the information-energy-conversion by observing Brownian motion of colloidal particles and controlling them. We introduced a feedback control protocol based on the information of Brownian particle by electric fields and found that the particle rotates against the torque exerted by an external electric field and obtains free energy larger than the amount of work performed on it. By measuring detailed process, validity of a new nonequilibrium equality concerning the feedback control has been shown. Efficiency of information-energy conversion was evaluated in this feedback system. Moreover, I will discuss on possible generalization of this cocept to information processing in cell chemotaxis. \\[4pt] [1] Leff, H. S. {\&} Rex, A. F. Maxwell's Demon 2: Entropy, Classical and Quatum Information, Computing (Inst. of Physics Pub. Inc., 2003).\\0pt] [2] Sagawa, T. {\&} Ueda, M. Minimal energy cost for thermodynamic information processing: Measurement and information erasure. Phys. Rev. Lett. 102, 250602 (2009).\\[0pt] [3] S. Toyabe, T. Sagawa, M. Ueda, E. Muneyuki, and M. Sano, Experimental demonstration of information-to-energy conversion and validation of the generalized Jarzynski equality, Nature Physics 6, 988 (2010).\\[0pt] [4] K. Kawaguchi and M. Sano, Free energy transduction in autonomous systems, J. Phys. Soc. Jpn. 80, 083003 (2011). [Preview Abstract] |
Monday, March 2, 2015 1:39PM - 2:15PM |
B46.00005: ABSTRACT WITHDRAWN |
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