Browsing by Author "Rai, Shailendra"

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    Assessment of future changes in high-impact precipitation events for India using CMIP6 models
    (Springer, 2023) Shahi, Namendra Kumar; Rai, Shailendra; Verma, S.; Bhatla, R.
    The main focus of this study is on the high-impact precipitation events of the Indian summer monsoon (ISM) that trigger devastating floods and landslides and cause widespread damage to lives, agriculture, and infrastructure. Here, 16 models from Coupled Model Intercomparison Project Phase 6 (CMIP6) have been used to evaluate the projected changes in the spatio-temporal distribution of high-impact/extreme precipitation events for the ISM under a high-emission scenario during 1941�2070 with respect to the historical period�of 1981�2010. The observed rain gauge-based precipitation datasets from two sources (i.e.,�the India Meteorological Department (IMD) and�the Climate Prediction Center (CPC)) have been used to analyze the ability of CMIP6 models in simulating the extreme precipitation characteristics of the ISM for the historical period. After a comprehensive assessment analysis, it was found that four out of a total of 16 CMIP6 models performed well in simulating the spatio-temporal distribution of extreme precipitation characteristics of the ISM for the historical period. Relative future changes in the spatio-temporal distribution of extreme precipitation characteristics with respect to the historical period indicate that the frequency, intensity, and spatial extent of high-impact precipitation events will increase with global warming over large parts of India. In particular, the total number of extreme events above the 99th percentile of the reference period is projected to increase by over 60% with a robust increase in the spatial extent of the number of extreme events in central India. The number of days with more than 50�mm of precipitation is projected to rise at a rate of over 40% per season over large parts of India and a robust amplification of heavy precipitation has also been observed. The projected changes are more prominent in the central India region. Overall, our results show a significant contribution of global warming in the rise of the frequency and intensity of extreme precipitation events. Furthermore, the response to global warming is plausibly consistent among the selected models�which provides greater confidence in the results and suggests the need for profound adaptation measures and better policy-making in the future. � 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.
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    Poor Glycemic Control Is Associated With Lower Interleukin-2 (IL-2) Levels and Low Macrophage Viability in Chronic Diabetic Foot Ulcers (DFUs)
    (SAGE Publications Inc., 2023) Banerjee, Tuhina; Rai, Shailendra; Singh, Aradhana; Goswami, Aakansha Giri; Ansari, Mumtaz Ahmed; Pratap, Arvind; Basu, Somprakas; Shukla, Vijay Kumar
    Low macrophage viability in chronic diabetic foot ulcers (DFUs) may lead to inadequate interleukin (IL) expression and the persistence of infection. This study evaluates the association between macrophage function, IL-2 expression, and wound microflora in chronic DFUs. Diabetic patients with DFUs (group 1, n = 40) and without DFUs (group 2, n = 40) were compared for macrophage function in serum by viability testing. Immunological response was measured by serum IL-1?, IL-2?, and IL-10 levels. The aerobic and anaerobic microflora of the DFUs were assessed by culture and molecular methods. Demographic, clinical, and biochemical factors were statistically analyzed by ?2 test and Student t test. Multiple correspondence analysis (MCA) was used to detect the pattern of association between glycosylated hemoglobin (hemoglobin A1c), serum IL-2 levels, and macrophage viability. Of the total DFU cases, 22 (55%) showed the presence of polymicrobial microflora. Low macrophage viability with predominant Gram-negative flora was seen in 10 (25%) cases in group 1. Serum IL-2 levels were significantly lower (P =.004) in patients in group 1 along with elevated levels of hemoglobin A1c (P =.038). MCA showed an association between low viability of macrophages and lower IL-2 levels and elevated hemoglobin A1c levels with lower serum IL-2 levels. As compared to group 2, the low viability of macrophages was significantly associated (P =.007) with lower IL-2 levels in group 1. Elevated hemoglobin A1c levels are strongly associated with lower IL-2 levels and low macrophage viability. This might be a contributing factor to the persistence of infections in chronic DFUs. � The Author(s) 2023.
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    Projected changes in the mean and intra-seasonal variability of the�Indian summer monsoon in the RegCM CORDEX-CORE simulations under higher warming conditions
    (Springer Science and Business Media Deutschland GmbH, 2021) Shahi, Namendra Kumar; Das, Sushant; Ghosh, Soumik; Maharana, Pyarimohan; Rai, Shailendra
    The present study employed the latest high-resolution regional climate model (RegCM4), driven by MPI-ESM-MR boundary conditions from the CORDEX-CORE South Asia framework to investigate the possible projected changes in the mean and intra-seasonal variability of the�Indian summer monsoon (ISM) precipitation and their associated dynamics during near future (NF; 2041�2060) and far future (FF; 2080�2099) with respect to the historical period (1995�2014) under RCP8.5 scenario. Extensive evaluation analysis indicates that the RegCM4 is fairly able to simulate the spatial�temporal distribution of the observed mean and extreme precipitation, low-level jet, and intra-seasonal variability i.e. active and break composite patterns of the precipitation anomalies over India during the historical period. A substantial decline in the projected precipitation during ISM is estimated over central and northwest India in NF (about 10�30%) as well as in FF (upto 50%), which may be attributed to the weakening and northward shift of low-level winds. The occurrences as well as the intensity of the extreme precipitation events are expected to increase over India in the future. The precipitation during the projected active spells will escalate over the monsoon core region. This is supported by the decrease in sea level pressure over land, which favors the winds to transport more moisture from the adjoining seas for the formation of convective clouds, which is partly indicated through the decline in net surface longwave radiation. On the other hand, the precipitation intensity during the projected break spells is expected to further decrease in the future. � 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.