The quasar PKS 0237-233: Chance coincidences and the alleged co redshift systems

It is shown that the number of redshifted CO absorption-line systems which are found in the spectrum of the quasar PKS 0237-233, using the rules of Varshalovich and Levshakov (1981), differ insignificantly from that that would be expected from chance coincidences. Consequently, the CO systems proposed by Varshalovich and Levshakov have no physical reality.     

Analysis of ventilation shock losses by finite element method

Summary This paper presents an analysis of ventilation shock losses using the two-dimensional finite element method. It outlines the finite element formulation, in which the ventilation air flow is assumed to be a steady-state, viscous, incompressible and fully developed turbulent flow. In addition, the modified version of Van Driest model is assumed for the effective kinematic viscosity.The shock losses were estimated for the case simulating the airway configuration for (a) split, (b) junction and (c) gradual contraction. The results are compared and discussed with the shock loss data available in the ventilation literature. To estimate the shock losses, the flow solution in terms of pressure was first obtained for each airway configuration using the finite element method. The solution was then compared with that of a straight airway for estimating the difference in the head losses.     

Structure,formation, and decomposition of APB's in calcic plagioclase

In calcic plagioclase (Ca, Na) [(Al, Si) AlSi₂O₈] Al-Si ordering produces superstructures with periodic and non periodic antiphase boundaries (APB's). Crystals growing at high temperature close to the melting point and cooling fairly rapidly order by nucleation of ordered domains which grow, resulting in an irregular pattern of curved APB's (b plagioclase). A modulated structure with periodic APB's forms by continuous ordering at large undercooling below the critical ordering temperature (e plagioclase). During annealing APB's are eliminated by pairwise recombination of adjacent APB's to reduce strain energy along the boundaries thereby transforming nonstable e plagioclase into stable b plagioclase without change in chemical composition. This process is often accompanied by a chemical phase separation with APB's providing favorable surfaces for diffusion. Transformations are documented by transmission electron microscopy (TEM) micrographs illustrating the variation in morphology of APB patterns in igneous and metamorphic plagioclase. They are in agreement with Korekawa et al.'s (1978) model of intermediate plagioclase which relies on periodic stacking of basic units rather than wavelike modulations. The paper includes observations of a new type of satellite in Stillwater bytownite (‘h’ satellites) which are due to fine lamellar exsolution.     

Roof bolting in underground mining: a state-of-the-art review

Conclusions With continuing investigations and developments, roof bolting today can in most cases successfully reinforce the mine roof in underground mining. In order to cope with the increasing use of roof bolts, efforts should be made to maximize the safety and minimize the cost. With regard to mechanical bolting, two important parameters need more advanced improvements and study, namely, optimum design of the shape and type of expansion shell and optimum bolt tension for a specific bolt pattern. For the fully grouted resin bolt, the most critical requirement is to develop a fast-setting, low-cost, intoxic, inflammable grouting material that can be used in the high speed mining cycle. It should be noted that geological conditions such as the strata type, rock properties,in situ stress, and planes of weakness play an important role in the successful application of any roof bolting system. These factors should be specified as accurately and quantitatively as possible in the design of any roof bolting system. Finally, proper and careful installation and continuous monitoring are imperative for the success of any roof bolting system.     

The effect of biological soil crusts of different successional stages and conditions on the germination of seeds of three desert plants

Biological soil crusts greatly affect soil surface properties, which, in turn, may alter seed germination of vascular plants. We investigated the effects of two types of biological soil crusts (moss crust and algal crust) at different ages on the seed germination of Bassia dasyphylla and Artemisia ordosica. We also investigated the effects of crust conditions (living crust and dead crust) on seed germination of B. dasyphylla, A. ordosica and Eragrostis poaeoides. The presence of both algal and moss crusts significantly enhanced the germination of B. dasyphylla and A. ordosica compared with uncrusted soil. Crust age had no significant effect on the germination of either B. dasyphylla or A. ordosica for both moss and algal crusts. Germination of B. dasyphylla differed significantly between moss and algal crusts, but germination of both A. ordosica and E. poaeoides did not. Germination of A. ordosica, E. poaeoides and B. dasyphylla was significantly higher on living algal crust than on dead crust and uncrusted soil, while living moss crust enhanced the germination of both A. ordosica and B. dasyphylla but had no significant effect on E. poaeoides.     

Use of the L2C signal for inversions of GPS radio occultation data in the neutral atmosphere

Results from processing FORMOSAT-3/COSMIC radio occultations (RO) with the new GPS L2C signal acquired both in phase locked loop (PLL) and open loop (OL) modes are presented. Analysis of L2P, L2C, and L1CA signals acquired in PLL mode shows that in the presence of strong ionospheric scintillation not only L2P tracking, but also L1CA tracking often fails, while L2C tracking is most stable. The use of L2C improves current RO processing in the neutral atmosphere mainly by increasing the number of processed occultations (due to significant reduction in the number of L2 tracking failures) and marginally by a reduction in noise in statistics. The latter is due to the combination of reduced L2C noise (compared to L2P) and increased L1CA noise in those occultations where L2P would have failed. This result suggests application of OL tracking for L1CA and L2C signals throughout an entire occultation to optimally acquire RO data. Two methods of concurrent processing of L1CA and L2C RO signals are considered. Based on testing of individual occultations, these methods allow: (1) reduction in uncertainty of bending angles retrieved by wave optics in the lower troposphere and (2) reduction in small-scale residual errors of the ionospheric correction in the stratosphere.     

Some factors influencing variations in the rate of natural increase of population in western Maharashtra

This paper analyzes the impact of various factors on variations in the rate of natural increase of population in Western Maharashtra, India. By using district level data, coefficients of correlation have been calculated between the rate of natural increase, the birth rate and the death rate on the 1 hand and different factors affecting them on the other. The analysis shows that in Western Maharashtra the birth rate is high in response to the high death rate and the high infant mortality rate. It is also revealed that the rate of natural increase of the population declines with an increase in the proportion of working females as well as the proportion of educated males. All this signifies that the region under study is in the 2nd stage of the "demographic transition."