On relativistic gasdynamics: invariance under a class of reciprocal-type transformations and integrable Heisenberg spin connections

Author(s):  
C. Rogers ◽  
T. Ruggeri ◽  
W. K. Schief

A classical system of conservation laws descriptive of relativistic gasdynamics is examined. In the two-dimensional stationary case, the system is shown to be invariant under a novel multi-parameter class of reciprocal transformations. The class of invariant transformations originally obtained by Bateman in non-relativistic gasdynamics in connection with lift and drag phenomena is retrieved as a reduction in the classical limit. In the general 3+1-dimensional case, it is demonstrated that Synge’s geometric characterization of the pressure being constant along streamlines encapsulates a three-dimensional extension of an integrable Heisenberg spin equation.

2003 ◽  
Vol 160 (4) ◽  
pp. 541-551 ◽  
Author(s):  
Enrico Schleiff ◽  
Jürgen Soll ◽  
Michael Küchler ◽  
Werner Kühlbrandt ◽  
Roswitha Harrer

The protein translocon of the outer envelope of chloroplasts (Toc) consists of the core subunits Toc159, Toc75, and Toc34. To investigate the molecular structure, the core complex was purified. This core complex has an apparent molecular mass of ∼500 kD and a molecular stoichiometry of 1:4:4–5 between Toc159, Toc75, and Toc34. The isolated translocon recognizes both transit sequences and precursor proteins in a GTP-dependent manner, suggesting its functional integrity. The complex is embedded by the lipids phosphatidylcholine and digalactosyldiacylglyceride. Two-dimensional structural analysis by EM revealed roughly circular particles consistent with the formation of a stable core complex. The particles show a diameter of ∼130 Å with a solid ring and a less dense interior structure. A three-dimensional map obtained by random conical tilt reconstruction of electron micrographs suggests that a “finger”-like central region separates four curved translocation channels within one complex.


Author(s):  
Graeme W Milton ◽  
Pierre Seppecher

We give a complete characterization of the possible response matrices at a fixed frequency of n -terminal electrical networks of inductors, capacitors, resistors and grounds, and of n -terminal discrete linear elastodynamic networks of springs and point masses, both in three-dimensional and two-dimensional cases. Specifically, we construct networks that realize any response matrix that is compatible with the known symmetry properties and thermodynamic constraints of response matrices. Owing to a mathematical equivalence, we also obtain a characterization of the response matrices of discrete acoustic networks.


1996 ◽  
Vol 449 ◽  
Author(s):  
R. Di Felice ◽  
J. E. Northrup ◽  
J. Neugebauer

ABSTRACTWe present a first-principles characterization of the initial stages of formation of AlN films on c-plane SiC substrates. Studying the competition between two-dimensional films and three-dimensional islands as a function of Al and N abundances, we find that a two-dimensional film can wet the surface in N-rich conditions. Ordered layer-by-layer growth can proceed to some extent on this wetting layer, and is improved by the formation of an atomically mixed interface which eliminates interface charge accumulation. Our results indicate that the stable AlN films grow in the (0001) orientation on the Si-terminated SiC(0001) substrate.


2013 ◽  
Vol 19 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Miquella G. Chavez ◽  
Wenli Yu ◽  
Brian Biehs ◽  
Hidemitsu Harada ◽  
Malcolm L. Snead ◽  
...  

Author(s):  
B-G Rosen ◽  
C Anderberg ◽  
R Ohlsson

Surface roughness plays an important role in the control of emissions and friction losses in the cylinder liner—piston ring system as well as securing economically favourable manufacturing. A number of different commercial cylinder liner types have been characterized using traditional two-dimensional stylus and ISO parameters together with the latest three-dimensional characterization. The results highlight the weak and strong correlations between different families of parameters traditionally used for liner surface specifications. The bearing curve based Rxq and Rk parameter families have been evaluated and show systematic and consistent differences when characterizing the same surface features when trying to establish independent characterization of the highly stratified, two-process cylinder liner surfaces. No significant improvement in discrimination results from using ensemble averages. Presentation of correlations in the form of topological diagrams helps to show when parameters with a high intrinsic variability can be effectively replaced by other more robust parameters with which they have a high correlation. Plateau parameters are in general more highly correlated than valley parameters. Three-dimensional parameters show high internal correlations and also correlate highly with some corresponding two-dimensional parameters.


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