Distribution and risk assessment of polychlorinated biphenyls (PCBs) in the remote air and soil of Manipur,India

∑₂₅PCB congeners including dioxin-like compounds were analyzed at three sites of Manipur India to assess the level of polychlorinated biphenyls (PCBs) in air and soil. The ∑₂₅PCBs were higher in urban air (average 2,454 pg/m³), followed by the mountain air (average 2,109 pg/m³) and rural air (average 1,756 pg/m³). PCB levels observed in urban air were higher compared to PCB levels reported in major Indian metropolitan cities especially along the coastal region and were comparable with the pristine sites of India and also with some pockets of China and Europe. The heavier congeners (tetra, penta, tri and hexa) were dominant in both air and soil samples and show significant correlation with the ambient temperature. Emission of PCB congeners was investigated from soil surface. The total organic carbon present in soil shows the significant correlation (r ² = 0.8; p < 0.05) with the PCBs could indicate that the PCBs originated from the similar sources. Principal component analysis revealed that the sources of higher chlorinated PCB congeners are local emissions while long-range atmospheric transport process is responsible behind elevated levels of lower chlorinated PCBs. Total calculated toxic equivalent (TEQ) levels in soil (37.17–160.5 pg/g) were superior to reported TEQ level of agricultural soil in Delhi, India (0.01–105.40 pg/g). Back trajectory analysis showed that the observed high levels of PCB at Manipur may due to movement of air masses, mostly from the Northern and Southern India and to some extent from Myanmar.     

Cosmic expansion driven by real scalar field for different forms of potential

We discuss the expansion of the universe in the FRLW model assuming that the source of dark energy is either tachyonic scalar field or quintessence. The tachyonic scalar field with exponential and power-law potential (function of homogeneous scalar field ?) both gives exponential expansion of the universe. It is found that this behaviour is not distinguishable from the quintessence with respect to these potentials.     

Spectroscopic Studies on Astrophysically Interesting TaO TaS, ZrS and SiO+ Molecules

The true experimental potential energy curves for the electronic ground states of astrophysically important TaO, TaS, ZrS and SiO⁺molecules are constructed by using the Rydberg–Klein–Rees method as modified by Vanderslice et al. The ground state dissociation energies are determined by curve fitting techniques using the five parameters Hulburt-Hirschfelder (H-H) function. The estimated dissociation energies are 8.19 ± 0.17, 6.9 ±0.14, 5.89 ± 0.12 and 5.75 ± 0.12 eVfor TaO, TaS, ZrS and SiO⁺ respectively. These values are in good agreement with the literature values. The r-centriods and Franck–Condon factors (FC Factors) for the bands of K ² φ _5/2 - X ² Δ _3/2 (K-X) system of TaO, A-X ² Δ (A-X) and B-X ² Δ (B-X)systems of TaS, B ¹ Π - X¹ Σ⁺ (B-X) system of ZrS and B ²Σ⁺ - X² Σ⁺ (B-X) and A ² Π - X² Σ⁺ (A-X)systems of SiO⁺ molecules have been calculated. The Franck–Condon factors (FC factors) are evaluated by the approximate analytical methods of Jarmain and Fraser. The absence of the bands of these systems is explained. This revised version was published online in July 2006 with corrections to the Cover Date.     

Infrared Observations Of Dust Emission From Comet Hale-Bopp

We present infrared imaging and photometry of the bright, giant comet C/1995 O1 (Hale-Bopp). The comet was observed in an extended infrared and optical observing campaign in 1996–1997. The infrared morphology of the comet was observed to change from the 6 to 8 jet “porcupine” structure in 1996 to the “pinwheel” structure seen in 1997; this has implications for the position of the rotational angular momentum vector. Long term light curves taken at 11.3 μm indicate a dust production rate that varies with heliocentric distance as ∶ r^−1.4. Short term light curves taken at perihelion indicate a rotational periodicity of 11.3 hours and a projected dust outflow speed of ∶ 0.4 km s⁻¹. The spectral energy distribution of the dust on October 31, 1996 is well modeled by a mixture of 70% silicaceous and 30% carbonaceous non-porous grains, with a small particle dominated size distribution like that seen for comet P/Halley (McDonnell et al., 1991), an overall dust production rate of 2 × 10⁵ kg s⁻¹, a dust-to-gas ratio of ∶5, and an albedo of 39%. This revised version was published online in July 2006 with corrections to the Cover Date.     

Impacts of sea-level rise on coastal zones of Mauritius: insights following calculation of a coastal vulnerability index

Natural Hazards - Whilst climate change has been regarded as a growing concern in recent years due the disruptive and detrimental effects experienced across the globe, one of its most compelling...     

A higher-dimensional string cosmological model in Brans–Dicke theory of gravitation

Field equations in the presence of cosmic string source are obtained in a scalar tensor theory of gravitation proposed by Brans and Dicke (Phys. Rev. 124, 925 (1961)) with the aid of a five-dimensional Kaluza–Klein metric. An exact string cosmological model is presented which represents a five-dimensional Reddy string (Astrophys. Space Sci. 286, 2003b) in Brans–Dicke theory. Some physical properties of the model are also discussed     

Bank branching and regional development in Malaysia

The regional imbalance in the Malaysian economy has long been recognised and continues to be a problem for development planning. The federal government has attempted to promote banking in the less developed regions in order to generate economic growth. Bank branches in Malaysia have increased in number and have also become regionally more dispersed. However, the regional concentration of bank branches is strongly associated with individual incomes. Hence, the growth of banking in Malaysia appears to be demand‐following rather than supply‐leading. Nevertheless, the intentional promotion of banking is continuing and beginning to produce some encouraging results.     

Causal viscous universe coupled with zero-mass scalar field in higher derivative theory

Cosmological solutions in the presence of an imperfect fluid and zero-mass scalar field are obtained in higher derivative theory. We investigate both power law and exponential expansion of the universe described by full causal theories proposed by Israel and Stewart. It is observed that energy density, co-efficient of bulk viscosity decrease with time in the presence of massless scalar field and temperature increase with expansion of universe.