Pseudomonas Cytochrome c551 at 2.0 angstrom Resolution: Enlargement of the Cytochrome c Family

The structure of respiratory cytochrome c551 of Pseudomonas aeruginosa, with 82 amino acids, has been solved by x-ray analysis and refined to a crystallographic R factor of 16.2%. It has the same basic folding pattern and hydrophobic heme environment as cytochromes c, c2, and c550, except for a large deletion at the bottom of the heme crevice. This same "cytochrome fold" appears to be present in photosynthetic cytochromes c of green and purple sulfur bacteria, and algal cytochromes f, suggesting a common evolutionary origin for electron transport chains in photosynthesis and respiration

A Visit to the Battlefield

This piece was transcribed and edited by Michael J. Birkner and Richard E. Winslow. With fighting concluded at Gettysburg on July 3, 1863, the enormous task of burying the dead, treating the wounded, and rehabilitating the town began in earnest. Although Gettysburg looked and smelled worse than it ever had or ever would again, thousands of people arrived on the battlefield in the days and weeks following General Robert E. Lee\u27s retreat. Some came to minister to the sick and reclaim the bodies of neighbors and loved ones; others scavenged souvenirs of the battle. Of the many visits to the battlefield in July 1863, few have been more affectingly described than the account of Joseph H. Foster of Portsmouth, New Hampshire. In the document reprinted below, of a speech Foster delivered at the Unitarian Sabbath School in Portsmouth on July 26, 1863, he describes a brief trip to Gettysburg from which he had just returned. His objective in going to Gettysburg was straightforward: he wanted to locate the body of his neighbor and friend Henry L. Richards and bring it back to New Hampshire for a proper interment. [excerpt

D-branes and the Non-commutative Structure of Quantum Spacetime

A worldsheet approach to the study of non-abelian D-particle dynamics is presented based on viewing matrix-valued D-brane coordinate fields as coupling constants of a deformed sigma-model which defines a logarithmic conformal field theory. The short-distance structure of spacetime is shown to be naturally captured by the Zamolodchikov metric on the corresponding moduli space which encodes the geometry of the string interactions between D-particles. Spacetime quantization is induced directly by the string genus expansion and leads to new forms of uncertainty relations which imply that general relativity at very short-distance scales is intrinsically described by a non-commutative geometry. The indeterminancies exhibit decoherence effects suggesting the natural incorporation of quantum gravity by short-distance D-particle probes. Some potential experimental tests are briefly described.Comment: 20 pages LaTeX, 3 eps figures, uses epsf.sty; Based on talks given by R.J.S. at SUSY'98, Oxford, England, July 11-17, 1998, and by N.E.M. at the 6th Hellenic School and Workshop on Elementary Particle Physics, TMR project "Physics Beyond the Standard Model", Corfu, Greece, September 15-18, 199

Entropy production in full phase space for continuous stochastic dynamics

The total entropy production and its three constituent components are described both as fluctuating trajectory-dependent quantities and as averaged contributions in the context of the continuous Markovian dynamics, described by stochastic differential equations with multiplicative noise, of systems with both odd and even coordinates with respect to time reversal, such as dynamics in full phase space. Two of these constituent quantities obey integral fluctuation theorems and are thus rigorously positive in the mean by Jensen's inequality. The third, however, is not and furthermore cannot be uniquely associated with irreversibility arising from relaxation, nor with the breakage of detailed balance brought about by non-equilibrium constraints. The properties of the various contributions to total entropy production are explored through the consideration of two examples: steady state heat conduction due to a temperature gradient, and transitions between stationary states of drift-diffusion on a ring, both in the context of the full phase space dynamics of a single Brownian particle