Thermodynamic metrics and optimal paths

A fundamental problem in modern thermodynamics is how a molecular-scale machine performs useful work, while operating away from thermal equilibrium without excessive dissipation. To this end, we derive a friction tensor that induces a Riemannian manifold on the space of thermodynamic states. Within the linear-response regime, this metric structure controls the dissipation of finite-time transformations, and bestows optimal protocols with many useful properties. We discuss the connection to the existing thermodynamic length formalism, and demonstrate the utility of this metric by solving for optimal control parameter protocols in a simple nonequilibrium model.Comment: 5 page

Advanced Communication Theory Techniques TECHNICAL DOCUMENTARY REPORT NO. ASD-TDR-63-186

Under this contract a number of topics have been studied and analyzed in detail in order to bring together and somewhat extend the concepts of communication theory as they apply to some current problems in digital communication systems. Radio wave channels are characterized by a model\u27 which accounts for both multiplicative and additive disturbances, A large amount of experimental data pertaining to radio disturbances is evaluated and correlated. She. importance of the Rayleigh fading channel is emphasized and previous work is extended to determine the capacity and efficiency of the Rayleigh, channel. Detection theory concepts have been extended to treat the problem of signal detection in the presence of statistically unknown additive disturbances. Several detectors based on non-parametric statistical techniques are treated in detail. Obese detectors are compared to the conventional likelihood detectors. Design procedures are formulated. Signal design techniques are used to optimize transmitted wave- forms and the improvement in system performance is determined. The criterion used in this\u27 analysis is the minimization of intersymbol influence and the minimization of transmitter power for a fixed probability of received, errors . The tradeoffs available between transmitter power and coding complexity are thoroughly investigated for the binary symmetric channel. Results are obtained for both Hamming and Bose-Chandhuri codes. Recommendations for further work in promising areas are made, the need to supplement theoretical work with experimental work is pointed ou

Environmental stress increases the entry of cytoplasmic organellar DNA into the nucleus in plants

Mitochondria and chloroplasts (photosynthetic members of the plastid family of cytoplasmic organelles) in eukaryotic cells originated more than a billion years ago when an ancestor of the nucleated cell engulfed two different prokaryotes in separate sequential events. Extant cytoplasmic organellar genomes contain very few genes compared with their candidate free-living ancestors, as most have functionally relocated to the nucleus. The first step in functional relocation involves the integration of inactive DNA fragments into nuclear chromosomes, and this process continues at high frequency with attendant genetic, genomic, and evolutionary consequences. Using two different transplastomic tobacco lines, we show that DNA migration from chloroplasts to the nucleus is markedly increased by mild heat stress. In addition, we show that insertion of mitochondrial DNA fragments during the repair of induced double-strand breaks is increased by heat stress. The experiments demonstrate that the nuclear influx of organellar DNA is a potentially a source of mutation for nuclear genomes that is highly susceptible to temperature fluctuations that are well within the range experienced naturally.Dong Wang, Andrew H. Lloyd and Jeremy N. Timmi