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An LRS Bianchi type I string dust cosmological model with and without bulk viscosity following a method used by Letelier and
Stachel, is investigated. To get a determine solution, it is assumed that σ∝θ whereσ is shear and θ is scalar of expansion
and which leads to A =αBn were n is a constant. The physical and geometrical aspects of the model are also discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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L.R.S. Bianchi Type I string dust cosmological models with and without magnetic field following the techniques used by Letelier
and Stachel, is investigated. To get a determinate solution, we assume a conditionσ is proportional to scalar of expansion
θ where σ is shear and θ is scalar of expansion and which leads to A=ℓ B
nwhere n is a constant and ℓ is proportionality constant. Some special models are also investigated by introducing the transformation,
, which leads to Riccati type differential equation. The physical and geometrical aspects of the models are also discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Natural Hazards - Indian coasts are often influenced by life-threatening water levels caused by tropical cyclones. To have a better long-term planning for the coastal districts due to tropical... 相似文献
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In Meghalaya, northeast India, the local people have the tradition of managing forest resources since early ages. The management practice varies and there are forests with high degree of protection, where no extraction (sacred forests) is allowed. There are also forests with moderate- level of protection and -extraction (reserved forests) as well as forests with low level of protection and open extraction (village forests). The present study was conducted to understand the impact of this traditional management system on the level of human disturbance, and on community composition and structure of the forests in Khasi hills of Meghalaya. The result revealed that disturbance index was low, whereas species richness, density and basal cover were significantly high in forests with high degree of protection (sacred forest) than those with low protection (reserved and village forest). Majority of endemic and threatened plant species were restricted to sacred forests as compared to the other forest types. Though these practices have ensured the sustainable use of forest resources by the local people but due to increased human- pressure and -disturbances, more effective conservation strategies need to be undertaken. Therefore, providing alternatives for fuel Received: 28 July 2016 Revised: 1 October 2016 Accepted: 15 December 2016 wood to local people, environmental education, encouraging afforestation and developmental activities involving local communities are recommended. 相似文献
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