Sunspots and physics of magnetic flux tubes overstability and Kelvin-Helmholtz instability in a magnetic field

We have studied the dynamical properties of convective overstability and Kelvin-Helmholtz instability in a vertical magnetic field with a downdraft. The Kelvin-Helmholtz instability and overstability produce the upward downward propagating Alfvén waves depending upon the magnitudes of the kinematic viscosity coefficient (eddy viscosity) ν, and thermometric conductivity κ. It is found that the instability may be driven by the density stratification and the effect of the eddy viscosity is to make the system stable. We discuss also the interaction of the overstability inx<0 and the downdraft inx>0, and the overstability at a vertical boundary of the field.     

Equivalent width of molecular lines in stars

We have calculated the expected equivalent widths of the individual rotational lines of the Lyman band of H₂ and (A-X) band of CO and SiO for Main Sequence stars. The results indicate that the lines of H₂ should be observable in absorption up toT _e9000 K. The lines of CO are found to be much weaker than those of H₂ lines. A discussion of these results is presented.     

Heavy metal distribution and contamination in soils of Thane–Belapur industrial development area,Mumbai, Western India

There is a growing public concern over the potential accumulation of heavy metals in soil, owing to rapid urban and industrial development in the last decade in India. Therefore, an attempt was made to investigate the pollution caused due to excessive accumulation of heavy metals in soils near Thane–Belapur industrial belt of Mumbai. Soil samples were collected from surrounding industrial areas and were analyzed for toxic/heavy metals by X-ray fluorescence spectrometer. The analytical results indicate that the soils in the study area were enriched with Cu, Cr, Co, Ni and Zn. The concentration ranges were: Cu 3.10–271.2 mg/kg (average 104.6 mg/kg), Cr 177.9–1,039 mg/kg (average 521.3 mg/kg), Co 44.8–101.6 mg/kg (average 68.7 mg/kg), Ni 64.4–537.8 mg/kg (average 183.6 mg/kg) and Zn 96.6–763.2 mg/kg (average 191.3 mg/kg). The visualization of spatial data is made by preparing distribution maps of heavy metal concentration in soils and co-relation diagrams. These results highlight the need for instituting a systematic and continuous monitoring of the study area for heavy metals and other forms of pollution to ensure that pollution does not become a serious problem in future.     

The absorption feature at 2200 Å in the interstellar reddening curve

The profile of the absorption feature at 2200 Å has been calculated for model grains of graphite, graphite core-dirty ice mantle and silicate. They are compared with the observed profile obtained by Bless and Savage from a number of early type stars. We have also shown that it is unlikely that the radiation damage of silicates in Interstellar Space can also contribute to the absorption feature at 2200 Å. Lastly, we have discussed briefly how one can meet the objections that have been raised on the silicate model.     

Solar cycle model for oscillating transient X-ray sources

The oscillations observed recently in the transient X-ray source A1118-61 are attributed to variations in the magnetic activity of a rotating white dwarf similar to the 11-year solar activity cycle. The transient nature, in analogy with the sun, is attributed to the variation in the strength of the cycle.Paper presented at the COSPAR Symposium on Fast Transients in X- and Gamma-Rays, held at Varna, Bulgaria, 29–31 May, 1975.     

Spectral responses of jojoba under salinity stress

Spectral reflectance characteristics of jojoba (Simmondsia chinensis (Link) Schneid.), a dioecious member of Buxaceae have been studied, especially under salinity stress. Reflectance is minimum at bands 1 and 2 (450–520 nm and 520–590 run) of visible range and maximum at bands 3 and 4 (620–680 nm and 770–860 nm) of near infrared range. At all wavelength intervals, male plants have greater reflectance than females. Reflectance in near infrared range (band 4) decreases with increasing age and leaf area index (LAI). A reverse trend occurs at band 3. Absorptance increases in visible as well as Infrared ranges with increasing salinity from control to 10 PSU of sea water concentration.     

Regional tourism and South-South economic cooperation

Regional tourism within developing countries is a growing phenomenon. Yet this aspect has been largely neglected in social science research as well as tourism planning. This paper highlights the general nature, scale and economic significance of regional tourism in three leading regions in Asia, Africa and Latin America. The topic is especially timely as economic self-reliance and cooperation are increasingly reiterated in the context of the emergence of regional groupings. A key question addressed is whether regional tourism development represents any new and viable prospects for regional economic improvement and partnership, especially compared to international tourism centred on attracting visitors from industrialized countries. Based on a critical assessment of the experiences of three regional blocs (ASEAN – the Association of South-East Asian Nations; SADC – the Southern African Development Community; and Mercosur – a common market comprising Argentina, Brazil, Paraguay and Uruguay, with Chile being an associated member), the paper suggests that a basic appreciation of the prospects of regional tourism is not enough to produce perceptible benefits. Regional tourism development is occurring in a haphazard manner, with little attention to managing existing socio-economic inequalities and centre-periphery relations. The paper is based primarily on the review of secondary literature readily available to the author combined with a few documents obtained directly from different regional organizations or through Internet search. A small amount of material, especially concerning emerging tourism trends and outcomes, is drawn from a research project on national mass tourism in developing countries coordinated by the author at the United Nations Research Institute for Social Development, Geneva.