Shock waves and type II radiobursts in the interplanetary medium

The planetary radio astronomy experiment on the Voyager spacecraft observed several type II solar radiobursts at frequencies below 1.3 MHz; these correspond to shock waves at distances between 20R and 1 AU from the Sun. We study the characteristics of these bursts and discuss the information that they give on shock waves in the interplanetary medium and on the origin of the high energy electrons which give rise to the radioemission. The relatively frequent occurence of type II bursts at large distances from the Sun favors the hypothesis of the emission by a longitudinal shockwave. The observed spectral characteristics reveal that the source of emission is restricted to only a small portion of the shock. From the relation between type II bursts, type III bursts and optical flares, we suggest that some of the type II bursts could be excited by type III burst fast electrons which catch up the shock and are then trapped.     

Solar gravitational redshift

Wavelengths of solar spectrum lines should be shifted toward the red by the Sun's gravitational field as predicted by metric theories of gravity according to the principle of equivalence. Photographic wavelengths of 738 solar Fe i lines and their corresponding laboratory wavelengths have been studied. The measured solar wavelength minus the laboratory wavelength (_observed) averaged for the strong lines agrees well with the theoretically predicted shift (_theoretical). Studies show that the departures depend on line strength. No dependence of the departures on wavelength was found within the existing data.By studying strong lines over a wide spectral range, velocity shifts caused by the complex motions in the solar atmosphere seem to affect the results in a minimal fashion.     

Contemporary urbanization and an optimal size for Soviet cities

This article is an English translation of the work cited in 46: 3092. The authors review the conclusions of Pivovarov (see 44: Title 3118) concerning the nature of the urbanization process and optimal city size in the USSR. The relationship between urbanization and the characteristics of a given socioeconomic system is examined, and the possibility of determining optimal size for cities of different functional types is evaluated     

The quasi integrals

The usual Von Zeipel transformations of the Hamiltonian Mechanics are presented, they lead to state functions with extremely slow variations: the quasi-integrals.The Von Zeipel transformations are implicit: an explicit and direct construction of the quasi-integrals is also presented and the quasi-invariance property of these functions is demonstrated.These results are applied to the problem of the motion of artificial satellites perturbed by the zonal harmonics of the Earth potential, the quasi-integral is given, it is then so constant that the problem can be considered as integrable.Proceedings of the Sixth Conference on Mathematical Methods in Celestial Mechanics held at Oberwolfach (West Germany) from 14 to 19 August, 1978.     

A crystal-chemical classification of borate structures with emphasis on hydrated borates

The rules governing formation of hydrated borate polyanions that were proposed by C.L. Christ in 1960 are critically reviewed and new rules added on the basis of recent crystal structure determinations. Principles and classifications previously published by others are also critically reviewed briefly. The fundamental building blocks from which borate polyanions can be constructed are defined on the basis of the number n of boron atoms, and the fully hydrated polyanions are illustrated. Known structures are grouped accordingly, and a shorthand notation using n and symbols Δ = triangle, T = tetrahedron is introduced so that the polyanions can be easily characterized. For example, 3:Δ+2T describes [B₃O₃(OH)₅]^2?. Correct structural formulas are assigned borates with known structures whereas borates of unknown structure are grouped separately.     

The sliding bed facies in esker sands and gravels: a criterion for full-pipe (tunnel) flow?

The Guelph esker (Ontario, Canada) consists of a sinuous, steep-sided and segmented ridge which comprises poorly sorted, matrix-supported sands and gravels. These sands and gravels were probably deposited during the sliding bed stage which has been observed by others in closed-conduit hydraulic experiments. The poor sorting probably resulted from a high concentration of bed-material load in the lower part of a subglacial tunnel, sorting being restricted to that produced by particle collisions. Inclusive graphic standard deviation is characteristically large for the sands and gravels, indicating that virtually all sizes available were in transport. The overall grain size distribution shows a characteristic undulatory shape on arithmetic probability paper, mostly because of selective removal of pebble gravel and granule sizes. This poorly sorted fades is believed to be diagnostic of transport in a subglacial tunnel flowing full of water, and may be used to identify subglacial conditions in other eskers. Deltaic sands and gravels occur downcurrent of the esker and contain a greater diversity of structures; climbing-ripple cross-laminae, parallel laminae and massive structure, deposited in large-scale foresees at the end of a subglacial tunnel. These deltaic sands and gravels grade distally into outwash sands and gravels.