This research paper examines a cosmological model in flat space-time via f(R,G)gravity,where R and G are the Ricci scalar and Gauss-Bonnet invariant,respectively.Our model assumes that f(R,G)is an exponential function...This research paper examines a cosmological model in flat space-time via f(R,G)gravity,where R and G are the Ricci scalar and Gauss-Bonnet invariant,respectively.Our model assumes that f(R,G)is an exponential function of G combined with a linear combination of R.We scrutinize the observational limitations under a power law cosmology that relies on two parameters,the Hubble constant(Ho)and the deceleration parameter(q)utilizing the 57-point H(z)data,8-point BAO data,1701-point Pantheon+data,joint data of H(z)+Pantheon,and joint data of H(z)+BAO+Pantheon+.The outcomes for H_(0)and q are realistic within observational ranges.We also address energy conditions,Om(z)analysis,and cosmographical parameters such as jerk,lerk,and snap.Our estimate of Ho is remarkably consistent with various recent Planck Collaboration studies that utilize the ACDM model.According to our study,power law cosmology within the context of f(R,G)gravity provides the most comprehensive explanation of the important aspects of cosmic evolution.展开更多
Background:Land use change plays a vital role in global carbon dynamics.Understanding land use change impact on soil carbon stock is crucial for implementing land use management to increase carbon stock and reducing c...Background:Land use change plays a vital role in global carbon dynamics.Understanding land use change impact on soil carbon stock is crucial for implementing land use management to increase carbon stock and reducing carbon emission.Therefore,the objective of our study was to determine land use change and to assess its effect on soil carbon stock in semi-arid part of Rajasthan,India.Landsat temporal satellite data of Pushkar valley region of Rajasthan acquired on 1993,2003,and 2014 were analyzed to assess land use change.Internal trading of land use was depicted throughmatrices.Soil organic carbon(SOC)stock was calculated for soil to a depth of 30 cm in each land use type in 2014 using field data collection.The SOC stock for previous years was estimated using stock change factor.The effect of land use change on SOC stock was determined by calculating change in SOC stock(t/ha)by deducting the base-year SOC stock from the final year stock of a particular land use conversion.Results:The total area under agricultural lands was increased by 32.14%while that under forest was decreased by 23.14%during the time period of 1993–2014.Overall land use change shows that in both the periods(1993–2003 and 2003–2014),7%of forest area was converted to agricultural land and about 15%changes occurred among agricultural land.In 1993–2003,changes among agricultural land led to maximum loss of soil carbon,i.e.,4.88 Mt C and during 2003–2014,conversion of forest to agricultural land led to loss in 3.16 Mt C.Conclusion:There was a continuous decrease in forest area and increase in cultivated area in each time period.Land use change led to alteration in carbon equity in soil due to change or loss in vegetation.Overall,we can conclude that the internal trading of land use area during the 10-year period(1993–2003)led to net loss of SOC stock by 8.29 Mt C.Similarly,land use change during 11-year period(2003–2014)caused net loss of SOC by 2.76 Mt C.Efforts should be made to implement proper land use management practices to enhance the SOC content.展开更多
基金support of the Ministry of Science and Higher Education of the Russian Federation(State contract GZ0110/23-10-IF)。
文摘This research paper examines a cosmological model in flat space-time via f(R,G)gravity,where R and G are the Ricci scalar and Gauss-Bonnet invariant,respectively.Our model assumes that f(R,G)is an exponential function of G combined with a linear combination of R.We scrutinize the observational limitations under a power law cosmology that relies on two parameters,the Hubble constant(Ho)and the deceleration parameter(q)utilizing the 57-point H(z)data,8-point BAO data,1701-point Pantheon+data,joint data of H(z)+Pantheon,and joint data of H(z)+BAO+Pantheon+.The outcomes for H_(0)and q are realistic within observational ranges.We also address energy conditions,Om(z)analysis,and cosmographical parameters such as jerk,lerk,and snap.Our estimate of Ho is remarkably consistent with various recent Planck Collaboration studies that utilize the ACDM model.According to our study,power law cosmology within the context of f(R,G)gravity provides the most comprehensive explanation of the important aspects of cosmic evolution.
文摘Background:Land use change plays a vital role in global carbon dynamics.Understanding land use change impact on soil carbon stock is crucial for implementing land use management to increase carbon stock and reducing carbon emission.Therefore,the objective of our study was to determine land use change and to assess its effect on soil carbon stock in semi-arid part of Rajasthan,India.Landsat temporal satellite data of Pushkar valley region of Rajasthan acquired on 1993,2003,and 2014 were analyzed to assess land use change.Internal trading of land use was depicted throughmatrices.Soil organic carbon(SOC)stock was calculated for soil to a depth of 30 cm in each land use type in 2014 using field data collection.The SOC stock for previous years was estimated using stock change factor.The effect of land use change on SOC stock was determined by calculating change in SOC stock(t/ha)by deducting the base-year SOC stock from the final year stock of a particular land use conversion.Results:The total area under agricultural lands was increased by 32.14%while that under forest was decreased by 23.14%during the time period of 1993–2014.Overall land use change shows that in both the periods(1993–2003 and 2003–2014),7%of forest area was converted to agricultural land and about 15%changes occurred among agricultural land.In 1993–2003,changes among agricultural land led to maximum loss of soil carbon,i.e.,4.88 Mt C and during 2003–2014,conversion of forest to agricultural land led to loss in 3.16 Mt C.Conclusion:There was a continuous decrease in forest area and increase in cultivated area in each time period.Land use change led to alteration in carbon equity in soil due to change or loss in vegetation.Overall,we can conclude that the internal trading of land use area during the 10-year period(1993–2003)led to net loss of SOC stock by 8.29 Mt C.Similarly,land use change during 11-year period(2003–2014)caused net loss of SOC by 2.76 Mt C.Efforts should be made to implement proper land use management practices to enhance the SOC content.
