Gravitational collapse of a Hagedorn fluid in Vaidya geometry

The gravitational collapse of a high-density null charged matter fluid, satisfying the Hagedorn equation of state, is considered in the framework of the Vaidya geometry. The general solution of the gravitational field equations can be obtained in an exact parametric form. The conditions for the formation of a naked singularity, as a result of the collapse of the compact object, are also investigated. For an appropriate choice of the arbitrary integration functions the null radial outgoing geodesic, originating from the shell focussing central singularity, admits one or more positive roots. Hence a collapsing Hagedorn fluid could end either as a black hole, or as a naked singularity. A possible astrophysical application of the model, to describe the energy source of gamma-ray bursts, is also considered.Comment: 14 pages, 2 figures, to appear in Phys. Rev.

Drought yield index to select high yielding rice lines under different drought stress severities

BACKGROUND Drought is the most severe abiotic stress reducing rice yield in rainfed drought prone ecosystems. Variation in intensity and severity of drought from season to season and place to place requires cultivation of rice varieties with different level of drought tolerance in different areas. Multi environment evaluation of breeding lines helps breeder to identify appropriate genotypes for areas prone to similar level of drought stress. From a set of 129 advanced rice (Oryza sativa L.) breeding lines evaluated under rainfed drought-prone situations at three locations in eastern India from 2005 to 2007, a subset of 39 genotypes that were tested for two or more years was selected to develop a drought yield index (DYI) and mean yield index (MYI) based on yield under irrigated, moderate and severe reproductive-stage drought stress to help breeders select appropriate genotypes for different environments. RESULTS ARB 8 and IR55419-04 recorded the highest drought yield index (DYI) and are identified as the best drought-tolerant lines. The proposed DYI provides a more effective assessment as it is calculated after accounting for a significant genotype x stress-level interaction across environments. For rainfed areas with variable frequency of drought occurrence, Mean yield index (MYI) along with deviation in performance of genotypes from currently cultivated popular varieties in all situations helps to select genotypes with a superior performance across irrigated, moderate and severe reproductive-stage drought situations. IR74371-70-1-1 and DGI 75 are the two genotypes identified to have shown a superior performance over IR64 and MTU1010 under all situations. CONCLUSION For highly drought-prone areas, a combination of DYI with deviation in performance of genotypes under irrigated situations can enable breeders to select genotypes with no reduction in yield under favorable environments compared with currently cultivated varieties. For rainfed areas with variable frequency of drought stress, use of MYI together with deviation in performance of genotypes under different situations as compared to presently cultivated varieties will help breeders to select genotypes with superior performance under all situations.Anitha Raman, Satish Verulkar B, Nimai Mandal P, Mukund Variar, V Shukla D, J Dwivedi L, B Singh N, O Singh N, Padmini Swain, Ashutosh Mall K, S Robin, R Chandrababu, Abhinav Jain, Tilatoo Ram, Shailaja Hittalmani, Stephan Haefele, Hans-Peter Piepho, and Arvind Kuma

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Not AvailableThe present study was conducted at ICAR-Central Agroforestry Research Institute, Jhansi to assess soil fertility status of groups of watershed along with control area. Soil samples were collected from three villages (Parasai, Chhatpur and Bachhauni) of watershed site-I of Jhansi district (U.P.), three villages (Shivrampur, Kundar and Dabar) of Tikamgarh district (M.P.) of watershed site-II and two villages (Ganeshgarh and Nayakhera) of Jhansi district (U.P.) as control site. The samples were collected from 0-15 cm soil depth with auger in grid fashion, following standard protocols and assessed for fertility parameters. The soils were slightly (pH: 7.3-7.8) to moderately alkaline (pH: 7.8-8.4). The organic carbon status ranged from low to medium, and available nitrogen (N) was found mostly in low category. The soil available phosphorus (P) was low to medium; available potassium (K) in medium range; and available sulphur (S) in low category. Regarding available micronutrients, boron (B) and zinc (Zn) were in low category, and level of copper (Cu), iron (Fe) and manganese (Mn) were in sufficient range. The assessment of soil fertility in watershed sites revealed that, watershed site-I had better soil fertility status as compared to watershed site-II and control site. Thus, the fertility status data suggests that organic carbon, N, P, S, B and Zn were major soil fertility constraints in the studied watershed areas in Bundelkhand region of semi-arid tropics, India.Not Availabl

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Not AvailableThe present study was conducted at ICAR-Central Agroforestry Research Institute, Jhansi to assess soil fertility status of groups of watershed along with control area. Soil samples were collected from three villages (Parasai, Chhatpur and Bachhauni) of watershed site-I of Jhansi district (U.P.), three villages (Shivrampur, Kundar and Dabar) of Tikamgarh district (M.P.) of watershed site-II and two villages (Ganeshgarh and Nayakhera) of Jhansi district (U.P.) as control site. The samples were collected from 0-15 cm soil depth with auger in grid fashion, following standard protocols and assessed for fertility parameters. The soils were slightly (pH: 7.3-7.8) to moderately alkaline (pH: 7.8-8.4). The organic carbon status ranged from low to medium, and available nitrogen (N) was found mostly in low category. The soil available phosphorus (P) was low to medium; available potassium (K) in medium range; and available sulphur (S) in low category. Regarding available micronutrients, boron (B) and zinc (Zn) were in low category, and level of copper (Cu), iron (Fe) and manganese (Mn) were in sufficient range. The assessment of soil fertility in watershed sites revealed that, watershed site-I had better soil fertility status as compared to watershed site-II and control site. Thus, the fertility status data suggests that organic carbon, N, P, S, B and Zn were major soil fertility constraints in the studied watershed areas in Bundelkhand region of semi-arid tropics, India.Not Availabl

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Not AvailableThe ravine areas are most fragile ecosystem and subjected to various kinds of natural resource losses and threat to biodiversity. Due to unregulated and over exploitation, the forest area under ravines are facing severe threats of losing biodiversity. In this context, a study was conducted to assess the tree diversity of ravine areas in different parts of Bundelkhand viz., Orai, Banda and Datia. In each study site, quadrats of 20 m × 20 m were randomly laid out and the tree diversity were documented. The species diversity, richness and evenness were studied using different indices like Shannon, Simpson, Margalef and Berger-Parker. The relative density and relative frequency were also calculated. In the present study, the Shannon diversity was highest in ravines of Datia (1.887) followed by Banda (1.871) and Orai (1.259). Whereas the Shannon equitability index was found higher in Banda (0.899) followed by Datia (0.859) and Orai (0.782). The lowest value of Simpson diversity was reported in Banda (0.183) followed by Datia (0.194) and Orai (0.333). In Datia (9 species) maximum number of species were recorded, followed by Banda (8 species) and Orai (5 species). The Inverted Berger-Parker dominance was highest in Banda (3.296) followed by Datia (2.804) and Orai (2.500). Hence it indicates that, ravine areas of Banda and Datia are more diverse and healthier than Orai. Further analysis revealed that, the relative density of Anogeissus pendula was highest in Orai (40.16%) and Datia (38.18%), whereas Holoptelea integrifolia (27.72%) and Balanites aegyptiaca (21.85%) population was higher in Banda. The overall diversity of all the three sites was found low. The survey also reported high biotic interferences, which escalates ravine degradation. However, crop cultivation in these lands is not desirable as it leads to accelerated erosion, thus adding to their fast degradation. The best scientific land use of these lands is to place them under permanent vegetation through agroforestry interventions involving forest and fruit trees along with the grasses. The planting and management of indigenous tree species like Anogeissus pendula, Acacia leucophloea, A. nilotica, Ziziphus spp., Carissa carandas and Capparis decidua will pave the way towards sustaining ravine ecosystem and livelihood of the people.Not Availabl