Browsing by Author "D. Sarkar"

Now showing 1 - 10 of 10

Collective enhancement in nuclear level density
(American Physical Society, 2019) G. Mohanto; A. Parihari; P.C. Rout; S. De; E.T. Mirgule; B. Srinivasan; K. Mahata; S.P. Behera; M. Kushwaha; D. Sarkar; B.K. Nayak; A. Saxena; A. K. Rhine Kumar; A. Gandhi; Sangeeta; Nabendu K. Deb; P. Arumugam
Several experimental investigations have reported evidence of collective enhancement of the nuclear level density and its fadeout. However, a suitable method is needed for experimental determination of the enhancement factor as a function of excitation energy. In this study, neutron spectra were measured in coincidence with evaporated α particles produced in the reactions B11+Ta181,Au197. The nuclear level density parameter has been extracted for the Os(A≈188) and Pb(A≈204) isotopes by comparing neutron spectra with statistical model prediction. Evidence for collective enhancement has been found for Os nuclei whereas no such enhancement has been seen for Pb nuclei. The energy-dependent enhancement factor has been extracted by simultaneous fitting of the neutron spectra at various excitation energies. Near a temperature of 0.8 MeV, the enhancement starts to fadeout which is lower than the theoretically predicted temperature of 1.4 MeV for Os187. Also, free energy surface calculation shows that the Os187 nucleus undergoes a transition from collective prolate to noncollective oblate shape close to the temperature of 0.8 MeV, corroborating the early fadeout. No such shape transition is seen for Pb203. © 2019 American Physical Society.
Combination therapy in management of NIDDM
(Association of Physicians of India, 1998) S.K. Singh; V.K. Shukla; D. Sarkar; J.K. Agrawal
[No abstract available]
Experimental study of the transfer-induced fission fragment angular distribution in the Li 6 + U 238 reaction
(American Physical Society, 2017) A. Parihari; G. Mohanto; Gurpreet Kaur; A. Jhingan; K. Mahata; R.G. Thomas; P.C. Rout; E.T. Mirgule; V.V. Desai; B. Srinivasan; C. Joshi; V. Mishra; M. Kushwaha; Shilpi Gupta; D. Sarkar; S.V. Suryanarayana; A. Shrivastava; N.L. Singh; A. Misra; B.K. Nayak; A. Saxena
Transfer-induced fission fragment angular distribution measurements have been carried out in Li6+U238 reaction at beam energies of 36 and 40 MeV in coincidence with projectile-like fragments. The fission fragment anisotropies for α- and deuteron-transfer-induced fission reactions are obtained with respect to the recoil direction. The anisotropy values for transfer-induced fissions are observed to be either similar or lower than the inclusive measurement. In order to quantitatively understand the present experimental data on transfer-induced fission, anisotropy values have been compared with the preequilibrium fission model considering ground-state spin of the projectile and/or target. It is found that the model predicts the inclusive and exclusive anisotropy data reasonably well. © 2017 American Physical Society.
Hashimoto's thyroiditis with ophthalmopathy and dermopathy
(1997) D. Sarkar; S.K. Singh; B. Bandopadhyaya; M. Kumar; J.K. Agrawal
[No abstract available]
Insulin Resistance and Urinary Excretion of Sodium in Hypertensive Patients with Non-Insulin Dependent Diabetes Mellitus
(1999) S.K. Singh; D. Sarkar; J.K. Agrawal
Background : Hyperinsulinemia has been implicated in the pathogenesis of hypertension both in non-diabetic and diabetic patients. A causal relationship between renal sodium retention and hyperinsulinemia is speculated to play role in the development of hypertension in diabetes mellitus. Material and Methods : Twenty patients (12 males; 8 females) with hypertension and non-insulin dependent diabetes mellitus (NIDDM) and twenty normotensive patients (11 males, 9 females) with NIDDM were included in the present study. Blood samples for glucose and immunoreactive insulin (IRI) assay were collected at 0, 30, 60 and 120 minutes after 75 g of glucose per oral. Urinary sodium excretion in 24 hrs was estimated by flame photometry. Insulin response to glucose and correlation between basal insulin secretion and urinary sodium excretion were evaluated. Results : Mean fasting plasma glucose value was significantly raised in hypertensive group in comparison with normotensive group of diabetic patients. Patients with diabetes and hypertension and significantly higher level of serum IRI than normotensive patients with diabetes mellitus. Urinary sodium excretion was significantly lower in diabetic patients with hypertension than in diabetic patients without hypertension. A negative correlation between basal insulin level and urinary Na+ excretion was observed in hypertensive patients with NIDDM. Conclusion : A negative correlation between hyperinsulinemia and 24 hrs urinary Na+ excretion was observed in patients with diabetes and hypertension. The study highlights that patients with diabetes mellitus have tendency to retain sodium under the influence of insulin but this needs further evaluation.
Metaphyseal Chondrodysplasia
(1999) D. Sarkar; S.K. Singh; J.K. Agrawal; Abha Gupta; Monica Sen
[No abstract available]
Neonatal hypothyroidism affects testicular glucose homeostasis through increased oxidative stress in prepubertal mice: effects on GLUT3, GLUT8 and Cx43
(Blackwell Publishing Ltd, 2017) D. Sarkar; S.K. Singh
Thyroid hormones (THs) play an important role in maintaining the link between metabolism and reproduction and the altered THs status is associated with induction of oxidative stress in various organs like brain, heart, liver and testis. Further, reactive oxygen species play a pivotal role in regulation of glucose homeostasis in several organs, and glucose utilization by Leydig cells is essential for testosterone biosynthesis and thus is largely dependent on glucose transporter 8 (GLUT8). Glucose uptake by Sertoli cells is mediated through glucose transporter 3 (GLUT3) under the influence of THs to meet energy requirement of developing germ cells. THs also modulate level of gap junctional protein such as connexin 43 (Cx43), a potential regulator of cell proliferation and apoptosis in the seminiferous epithelium. Although the role of transient neonatal hypothyroidism in adult testis in terms of testosterone production is well documented, the effect of THs deficiency in early developmental period and its role in testicular glucose homeostasis and oxidative stress with reference to Cx43 in immature mice remain unknown. Therefore, the present study was conducted to evaluate the effect of neonatal hypothyroidism on testicular glucose homeostasis and oxidative stress at postnatal days (PND) 21 and 28 in relation to GLUT3, GLUT8 and Cx43. Hypothyroidism induced by 6-propyl-2-thiouracil (PTU) markedly decreased testicular glucose level with considerable reduction in expression level of GLUT3 and GLUT8. Likewise, lactate dehydrogenase (LDH) activity and intratesticular concentration of lactate were also decreased in hypothyroid mice. There was also a rise in germ cell apoptosis with increased expression of caspase-3 in PTU-treated mice. Further, neonatal hypothyroidism affected germ cell proliferation with decreased expression of proliferating cell nuclear antigen (PCNA) and Cx43. In conclusion, our results suggest that neonatal hypothyroidism alters testicular glucose homeostasis via increased oxidative stress in prepubertal mice, thereby affecting germ cell survival and proliferation. © 2017 American Society of Andrology and European Academy of Andrology
Regional climate model performance and application of bias corrections in simulating summer monsoon maximum temperature for agro-climatic zones in India
(Springer, 2020) R. Bhatla; D. Sarkar; S. Verma; P. Sinha; S. Ghosh; R.K. Mall
The present study evaluates the performance of Conformal-Cubic Atmospheric Model (CCAM) simulations downscaled from six global climate models (GCMs) (i.e., ACCESS1.0, CNRM-CM5, CCSM4, GFDL-CM3, MPI-ESM-LR, and NorESM-M) and Max Plank’s Regional Model (REMO2009(MPI)) obtained from the South-Asia Coordinated Regional Climate Downscaling Experiment (CORDEX) for analyzing the summer monsoon maximum temperature (Tmax) over the fifteen Agro-Climatic Zones (ACZs) in India. The model simulations are compared with the two sets of observed data obtained from the India Meteorology Department (IMD) and Climate Research Unit (CRU) for the period from 1981 to 2005. The results illustrate that the skill of CCAM regional climate models (RCMs) is higher than the REMO in simulating the Tmax over all the regions. The spatial patterns of Tmax in CCAM (CCSM) and CCAM (CNRM) are closer to IMD, while the Tmax distributions in CCAM (CNRM), CCAM (CCSM), and CCAM (BCCR) agree well with the CRU, and correlation coefficient (CC) is more than 0.6; however, large positive biases in all RCMs are depicted over the Himalayan regions. The inter-comparison among all the RCMs suggest that the CCAM (CNRM) and CCAM (CCSM) are rendering as the foremost models in simulating Tmax over different ACZs. Performances of these two models also infer the usefulness of the model products for impact studies over the individual ACZs. However, the existing systematic biases in the RCMs impeded the model performance and it is necessary to remove the model bias prior to some real-time application. In this study, two bias correction methods, i.e., linear scaling (LS) and distribution mapping (DM), have been used to correct RCM output bias. It is found that the model performance using DM correction is better than LS method. The performance validations are evaluated based on the probability density function (PDF), CC, and standard deviation (SD) with 95% confidence level. The model evaluation has also been justified using mean absolute error (MAE) index, Nash-Sutcliffe coefficient (NS) index, percent bias (Pbias), and the Willmott’s index of agreement (d) which confirm the research findings. The results are providing an effective guidance on the usefulness of bias corrected RCMs over a particular ACZs for impact assessment. © 2020, Springer-Verlag GmbH Austria, part of Springer Nature.
Study of insulin resistance in polycystic ovary disease
(1997) N. Gera; S.K. Singh; D. Sarkar; V. Agarwal; V.P. Jyotsana; N.K. Agrawal; J.K. Agrawal; R.P. Bhatt
Twenty-one patients of Polycystic Ovary Disease (PCOD) divided in two groups obese (Body Mass Index (BMI) > 25) and non-obese (BMI ≤ 25), alongwith 40 controls (33 obese and 7 non-obese) have been evaluated for their plasma glucose and insulin levels in the fasting state and after 75 Gm oral glucose challenge with an aim to study glucose tolerance and insulin resistance in PCOD. Plasma glucose, and area under glucose curve did not reveal significant difference in obese and lean PCOD as compared to corresponding control groups. However, plasma insulin, area under insulin curve and insulin-glucose ratio were greater in both obese and lean PCOD in comparison to the controls. Between the two PCOD groups, obese PCOD had significantly higher values, although their mean FSH, LH, prolactin and testosterone levels were statistically similar thus showing a lack of correlation between these hormone levels and insulin resistance in obese and non-obese PCOD subjects. Our study shows that hyperinsulinaemia and insulin resistance are an integral part of PCOD, the abnormality being much more in obese PCOD. Possibly, hyperinsulinaemia and insulin resistance have pathogenic significance in PCOD, but there was lack of correlation between testosterone or other hormone levels, with insulin resistance and hyperinsulinaemia.
Tumoral calcinosis with bladder stone
(1997) S.K. Singh; S.K. Saraf; D. Sarkar; N. Gera; B. Bandopadhyaya; A. Gupta; J.K. Agarwal
[No abstract available]