Residual entropy of the one-dimensional Ising antiferromagnet with general spin

We have calculated the ground-state degeneracy and the concominant residual entropy of the one-dimensional Ising antiferromagnet in a critical magnetic field. We demonstrate that the results obtained can be related to the ground-state properties of the q-state Potts antiferromagnet in the corresponding external field.     

A model of structure periodically modulated in three dimensions

A model of structure periodically modulated in three dimensions is calculated in the presented paper and applied to the alloy Cu₈₀Au₂₀. The existence and intensity of the side-bands of the Bragg lines appearing with hyperstructural lines on films of this alloy after heating to temperature on the border of the order-disorder transformation are explained by means of the given model and the value of the period of sinusoidal variation of the lattice parameter and scattering power is calculated.ikova 22, Brno, Czechoslovakia.The author thanks Mrs. V. Gregor and Mr. M. Jelínek who prepared the necessary pictures.     

Optical information processing by the Fabry-Perot resonator

Properties of the Fabry-Perot resonator as a part of an optical imaging system are discussed from the point of view of optical information theory. Information capacity of the system is derived and expressed in terms of the number of degrees of freedom of the optical wave field at the output. It is pointed out that the Fabry-Perot resonator is well suited for processing of image signals having a periodic structure.     

Manifestation of microgel-like particles of styrene-ethylene dimethacrylate copolymers in solution in 1H and 13C NMR spectra

From the integrated intensities of ¹H NMR bands it has been found that in solutions of styrene (St)-ethylene dimethacrylate (EDMA) copolymers, a considerable part of the monomer units do not show directly in high-resolution ¹H NMR spectra and it is suggested that these monomer units form compact structures, probably acting as cores of microgel-like particles. In ¹³C NMR spectra all monomer units are shown, including those which are part of the compact microgel structures. From a comparison of ¹H NMR spectra with other analytical methods (elemental analysis, infrared spectra) it follows that the composition of the copolymer in the core of the microgel is the same as the overall composition of the copolymer. The content of the compact structures in the microgel increases with the content of the EDMA component. The results are discussed from the point of view of structural features and of the motional restrictions of the St/EDMA copolymers in CCl₄ solution. The consequences for ¹H NMR analysis of copolymer composition are also discussed.     

External inversion,internal inversion,and reflection invariance

Having in mind that physical systems have different levels of structure we develop the concept of external, internal and total improper Lorentz transformation (space inversion and time reversal). A particle obtained from the ordinary one by the application of internal space inversion or time reversal is generally a different particle. From this point of view the intrinsic parity of a nuclear particle (elementary particle) is in fact the external intrinsic parity, if we take into account the internal structure of a particle. We show that non-conservation of the external parity does not necessarily imply noninvariance of nature under space inversion. The conventional theory of beta-decay can be corrected by including the internal degrees of freedom to become invariant under total space inversion, though not under the external one.