On the shell star pleione (BU Tauri)

BU Tauri (Pleione) an interesting star in the Pleiades cluster, has been observed spectrophotometrically. The energy distribution curves of the star have been discussed vis a vis model atmospheres for normal stars in the appropriate range of temperature and effective gravity. The changes in the energy distribution curve noticed during our observations and previous observations taken from the literature have been pointed out. On the basis of the measured Há emission equivalent width, a rough estimate of the dimensions of the extended envelope of the star has been made.     

An analysis of the atmosphere of T Vulpeculae

Ten spectrograms of T Vul at a dispersion of 8.47 Å mm^–1 have been used for an analysis of the parameters of stellar atmosphere during its pulsation cycle. A differential curve of growth method relative to the Sun has been used to evaluate atmospheric parameters. The range in _exc is from 0.88 to 1.00. Mean abundances for twenty elements have been estimated relative to [N _Fe]. A deficiency by a factor of 2.4 has been found ins-process elements with respect to those formed by thee-process.     

Application of Hidden Markov Model for avalanche danger simulations for road sectors in North-West Himalaya

Seismic hazard assessment is the key tool for rational planning, safety and design of infrastructures in seismically vulnerable regions. Gujarat is the only state in peninsular India with the maximum seismic hazard of large shallow earthquakes originating from intra-plate seismicity. Probabilistic seismic hazard assessment (PSHA) of Gujarat is carried out in this paper. Three seismogenic sources, namely Kutch, Saurashtra and Mainland Gujarat, are considered, and seismicity parameters are estimated separately for each region taking into account the completeness of the available earthquake data. Peak ground acceleration (PGA) of the horizontal component and spectral acceleration at specific periods are considered as the intensity measures. Ground motion predictive equation chosen was reported to be based on simulated ground motions and verified against the strong motion records in the study region. Results are reported for the 17 major cities at the bedrock and also for the soil sites. Apart from hazard curves, 2475 and 475 years of return periods are considered for the PGA and uniform hazard spectra (UHS). The results are compared with the present recommendations of Indian Standards. Key observations include (1) Indian Standards underpredict PGA in the entire Gujarat when the soil sites are considered and in a few cities even at the bedrock; (2) amplification of PGA (or short period hazard) on account of soil sites should be included in the Indian Standard, which is currently absent; (3) shape of the UHS indicates that a separate amplification is required at the hyperbolic portion; and (4) ratio of 2475–475 years of PGA, which is considered 2.0 in Indian Standard, should be reduced to 1.5. Time-dependent recurrence model is also included in this paper and compared with conventional PSHA. General observations include that (1) hazard may increase significantly on account of time dependency; (2) this also influences the disaggregation and in turn the selection of ground motions; and (3) time since last earthquake significantly influences the extent of the effect of time dependency.     

Search for and study of photometric variability in magnetic white dwarfs

We report the results of photometric observations of a number of magnetic white dwarfs in order to search for photometric variability in these stars. These V-band observations revealed significant variability in the classical highly magnetized white dwarf GRW+70?8247 with a likely period from several days to several dozen days and a half-amplitude of about 0_. ^m 04. Our observations also revealed the variability of the well-known white dwarf GD229. The half amplitude of its photometric variability is equal to about 0_. ^m 005, and the likely period of this degenerate star lies in the 10–20 day interval. This variability is most likely due to the rotation of the stars considered.We also discuss the peculiarities of the photometric variability in a number of other white dwarfs. We present the updated “magnetic field–rotation period” diagram for the white dwarfs.     

Tannery Effluents: Current Practices,Environmental Consequences,Human Health Risks,and Treatment Options

The tannery industry influences the gross domestic product/economic activity of any country, but the uncontrolled release of tannery effluents causes environmental degradation and increases health risks to human. The reason for the toxicity of tannery effluents is the presence of high concentrations of organic and inorganic chemicals used in the production of leather goods. Untreated or partially treated effluents discharged into surface water results in an increase in both chemical and biological oxygen demand as well as in an increase in the levels of total suspended solids, dissolved solids, and toxic metals in environmental bodies, especially in soil, water bodies, and water sediments. Various treatment techniques, such as physicochemical, biological, and advanced oxidation methods, which include chemical precipitation, electrocoagulation, aerobic or anaerobic treatment, wetland construction, and Fenton, electro-Fenton, and photo-Fenton processes are also described. This review also discusses the technical appropriateness and economic feasibility of reducing the effluent pollution load and solid waste emanating from the tannery industry. Considering the enhanced health risks in the tannery waste treatment and management regime, some green and advanced technologies should be explored. A sustainable green technology that avoids the use of toxic chemicals in the tanning process is seen well for ecological health.     

A multi-model decision support system (MM-DSS) for avalanche hazard prediction over North-West Himalaya

Natural Hazards - Avalanche forecasting is carried out using physical as well as statistical models. All these models have certain limitations associated with their mathematical formulation that...     

Habitat Suitability Assessment of <Emphasis Type="Italic">Ardeotis nigriceps</Emphasis> (Vigors) in Great Indian Bustard Sanctuary,Maharashtra (India) Using Remote Sensing and GIS

Ardeotis nigriceps, commonly known as Great Indian Bustard (GIB), is a Critically Endangered, Evolutionary Distinct and Globally Threatened (EDGE) and endemic species to the Indian subcontinent. GIB is under tremendous threat in its last strongholds and sliding inextricably towards extinction. The GIB sanctuary in Maharashtra (India) is one of the last refuges of the bird constituting an area of 8496 km² spread over in seven talukas of Solapur and Ahemednagar districts. Major portion of the sanctuary (94.3 %) consists of privately owned lands under a variety of economic vocations and large number of villages and townships. In view of the legal restrictions relating to Protected Area under the Wildlife (Protection) Act of India 1972, the inhabitants of villages and townships faced a very difficult situation regarding use of their lands, development of properties and deriving benefits from planned local and regional development. This created conflict between local people and the forest department over the use of land, which necessitated the rationalization of the sanctuary. The objective of the present study was to map the suitable habitat of GIB in GIB Wildlife Sanctuary as an input for the realignment of the GIB Sanctuary by identifying areas that are important for the GIB. Main parameters considered for the habitat suitability assessments are, habit and habitat of GIB, slope, minimum patch size and disturbance sources. Based on the criteria derived for the ecological and biological requirements of GIB, binary deductive habitat suitability modeling has been done using remote sensing and GIS and prioritized the potential habitats of GIB. The net area of important suitable habitat of GIB in GIB sanctuary is 2304.99 km² out of 8496.44 km². The output of the present study has been used as an input by the committee (set by Honorable Supreme court of India) on rationalization of the GIB Sanctuary and the sanctuary has been rationalized with an area of 1222 km².     

Search for orbital motion of the pulsar 4U 1626–67: Candidate for a neutron star with a supernova fall-back accretion disk

We report here results from a new search for orbital motion of the accretion powered X-ray pulsar 4U 1626–67 using two different analysis techniques. X-ray light curve obtained with the Proportional Counter Array of the Rossi X-ray Timing Explorer during a long observation carried out in February 1996, was used in this work. The spin period and the local period derivative were first determined from the broad 2–60 keV energy band light curve and these were used for all subsequent timing analysis. In the first technique, the orbital phase dependent pulse arrival times were determined for different trial orbital periods in the range of 500 to 10,000 s. We have determined a 3σ upper limit of 13 lt-ms on the projected semimajor axis of the orbit of the neutron star for most of the orbital period range, while in some narrow orbital period ranges, covering about 10% of the total orbital period range, it is 20lt-ms. In the second method, we have measured the pulse arrival times at intervals of 100 s over the entire duration of the observation. The pulse arrival time data were used to put an upper limit on any periodic arrival time delay using the Lomb-Scargle periodogram. We have obtained a similar upper limit of 10 lt-ms using the second method over the orbital period range of 500–10,000 s. This puts very stringent upper limits for the mass of the compact object except for the unlikely case of a complete face-on orientation of the binary system with respect to our line-of-sight. In the light of this measurement and the earlier reports, we discuss the possibility of this system being a neutron star with a supernovae fall-back accretion disk.