3,048 results on '"Gupta Y"'
Search Results
2. Observation of near-scission 'polar' and 'equatorial' proton emission in heavy-ion induced fission
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Singh, Pawan, Gupta, Y. K., Prajapati, G. K., Joshi, B. N., Prajapati, V. G., Sirswal, N., Ramachandran, K., Pradeep, A. S., Dagre, V. S., Kumar, M., Jhingan, A., Deshmukh, N., John, B. V., Nayak, B. K., Biswas, D. C., and Choudhury, R. K.
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Nuclear Experiment ,Nuclear Theory - Abstract
Proton and $\alpha$-particle energy spectra were measured in coincidence with fission fragments at different relative angles in $^{16}$O (96 MeV) + $^{232}$Th reaction. The multiplicity spectra were analyzed within the framework of a Moving Source Disentangling Analysis (MSDA) to determine contributions from different emission stages. The MSDA conclusively shows ``Near Scission Emission (NSE)" as an essential component in the multiplicity spectra. In contrast to NSE $\alpha$ particles which emit mainly perpendicular (``equatorial emission"), the NSE protons are observed to be emitted perpendicular as well as parallel (``polar emission") to the fission axis with similar intensities ($\sim$20\% for each). Thus, around 40\% of total pre-scission protons are emitted near the scission stage, whereas the same fraction for $\alpha$ particles is only around 10\%. The inevitable presence of ``polar" and ``equatorial" NSE protons in a heavy-ion induced fission has been observed for the first time. Present results open up a new avenue to study the heavy-ion induced fission dynamics.
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- 2024
3. Serum Levels of Autoantibodies Against Extracellular Antigens and Neutrophil Granule Proteins Increase in Patients with COPD Compared to Non-COPD Smokers
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Ma A, Wen L, Yin J, Hu Y, Yue X, Li J, Dong X, Gupta Y, Ludwig RJ, Krauss-Etschmann S, Riemekasten G, Petersen F, and Yu X
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chronic obstructive pulmonary disease ,autoimmunity ,autoantibody profile ,neutrophil granule proteins ,lactorferrin. ,Diseases of the respiratory system ,RC705-779 - Abstract
Aiping Ma,1,* Lifang Wen,2,* Junping Yin,3 Yi Hu,4 Xiaoyang Yue,3 Jiurong Li,1 Xiaoru Dong,2 Yask Gupta,5 Ralf J Ludwig,5 Susanne Krauss-Etschmann,3,6 Gabriela Riemekasten,7 Frank Petersen,3 Xinhua Yu2,3 1Department of Respiratory Medicine, The First Affiliated Hospital, School of Medicine, Xiamen University, Xiamen, People’s Republic of China; 2Xiamen-Borstel Joint Laboratory of Autoimmunity, The Medical College of Xiamen University; 3Priority Area Asthma and Allergy, Research Center Borstel, Airway Research Center North (ARCN), Members of the German Center for Lung Research (DZL), Borstel, Germany; 4Department of Clinical Laboratory, The First Affiliated Hospital, School of Medicine, Xiamen University, Xiamen, People’s Republic of China; 5Lübeck Institute of Experimental Dermatology, University of Lübeck, Lübeck, Germany; 6Institute for Experimental Medicine, Christian-Albrechts-Universitaetzu Kiel, Kiel, Germany; 7Department of Rheumatology, University of Lübeck, Lübeck 23538, Germany*These authors contributed equally to this workCorrespondence: Xinhua YuPriority Area Asthma and Allergy, Research Center Borstel, Borstel 23845, GermanyTel +49 453 7188 2520Email xinhuayu@fz-borstel.deBackground: Chronic obstructive pulmonary disease (COPD) is a highly prevalent disease leading to irreversible airflow limitation and is characterized by chronic pulmonary inflammation, obstructive bronchiolitis and emphysema. Etiologically, COPD is mediated by toxic gases and particles, eg, cigarette smoke, while the pathogenesis of the disease is largely unknown. Several lines of evidence indicate a link between COPD and autoimmunity but comprehensive studies are lacking.Methods: By using a protein microarray assaying more than 19,000 human proteins we determined in this study the autoantibody profiles of COPD and non-COPD smokers. The discovery cohort included 5 COPD patients under acute exacerbation (AECOPD) and 5 age- and gender-matched non-COPD smokers. One putative candidate autoantibody, anti-lactoferrin IgG, was further investigated by using immunoblotting with a large validation cohort containing 124 healthy controls, 92 patients with AECOPD and 52 patients with stable COPD.Results: We show that i) autoantigens targeted by autoantibodies with higher titers in COPD patients were enriched in extracellular regions, while those with lower titers in COPD patients were enriched in intracellular compartments. ii) levels of IgG autoantibodies against many neutrophil granule proteins were significantly higher in COPD patients than in non-COPD smokers. Furthermore, increased levels of anti-lactoferrin antibodies in COPD patients were confirmed in a cohort with a large number of samples.Conclusion: The comprehensive autoantibody profiles from COPD patients established in this study demonstrated for the first time a shift in the cellular localization of antigens targeted by autoantibodies in COPD.Keywords: chronic obstructive pulmonary disease, autoimmunity, autoantibody profile, neutrophil granule proteins, lactoferrin
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- 2020
4. Comparing recent PTA results on the nanohertz stochastic gravitational wave background
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The International Pulsar Timing Array Collaboration, Agazie, G., Antoniadis, J., Anumarlapudi, A., Archibald, A. M., Arumugam, P., Arumugam, S., Arzoumanian, Z., Askew, J., Babak, S., Bagchi, M., Bailes, M., Nielsen, A. -S. Bak, Baker, P. T., Bassa, C. G., Bathula, A., Bécsy, B., Berthereau, A., Bhat, N. D. R., Blecha, L., Bonetti, M., Bortolas, E., Brazier, A., Brook, P. R., Burgay, M., Burke-Spolaor, S., Burnette, R., Caballero, R. N., Cameron, A., Case, R., Chalumeau, A., Champion, D. J., Chanlaridis, S., Charisi, M., Chatterjee, S., Chatziioannou, K., Cheeseboro, B. D., Chen, S., Chen, Z. -C., Cognard, I., Cohen, T., Coles, W. A., Cordes, J. M., Cornish, N. J., Crawford, F., Cromartie, H. T., Crowter, K., Curyło, M., Cutler, C. J., Dai, S., Dandapat, S., Deb, D., DeCesar, M. E., DeGan, D., Demorest, P. B., Deng, H., Desai, S., Desvignes, G., Dey, L., Dhanda-Batra, N., Di Marco, V., Dolch, T., Drachler, B., Dwivedi, C., Ellis, J. A., Falxa, M., Feng, Y., Ferdman, R. D., Ferrara, E. C., Fiore, W., Fonseca, E., Franchini, A., Freedman, G. E., Gair, J. R., Garver-Daniels, N., Gentile, P. A., Gersbach, K. A., Glaser, J., Good, D. C., Goncharov, B., Gopakumar, A., Graikou, E., Grießmeier, J. -M., Guillemot, L., Gültekin, K., Guo, Y. J., Gupta, Y., Grunthal, K., Hazboun, J. S., Hisano, S., Hobbs, G. B., Hourihane, S., Hu, H., Iraci, F., Islo, K., Izquierdo-Villalba, D., Jang, J., Jawor, J., Janssen, G. H., Jennings, R. J., Jessner, A., Johnson, A. D., Jones, M. L., Joshi, B. C., Kaiser, A. R., Kaplan, D. L., Kapur, A., Kareem, F., Karuppusamy, R., Keane, E. F., Keith, M. J., Kelley, L. Z., Kerr, M., Key, J. S., Kharbanda, D., Kikunaga, T., Klein, T. C., Kolhe, N., Kramer, M., Krishnakumar, M. A., Kulkarni, A., Laal, N., Lackeos, K., Lam, M. T., Lamb, W. G., Larsen, B. B., Lazio, T. J. W., Lee, K. J., Levin, Y., Lewandowska, N., Littenberg, T. B., Liu, K., Liu, T., Liu, Y., Lommen, A., Lorimer, D. R., Lower, M. E., Luo, J., Luo, R., Lynch, R. S., Lyne, A. G., Ma, C. -P., Maan, Y., Madison, D. R., Main, R. A., Manchester, R. N., Mandow, R., Mattson, M. A., McEwen, A., McKee, J. W., McLaughlin, M. A., McMann, N., Meyers, B. W., Meyers, P. M., Mickaliger, M. B., Miles, M., Mingarelli, C. M. F., Mitridate, A., Natarajan, P., Nathan, R. S., Ng, C., Nice, D. J., Niţu, I. C., Nobleson, K., Ocker, S. K., Olum, K. D., Osłowski, S., Paladi, A. K., Parthasarathy, A., Pennucci, T. T., Perera, B. B. P., Perrodin, D., Petiteau, A., Petrov, P., Pol, N. S., Porayko, N. K., Possenti, A., Prabu, T., Leclere, H. Quelquejay, Radovan, H. A., Rana, P., Ransom, S. M., Ray, P. S., Reardon, D. J., Rogers, A. F., Romano, J. D., Russell, C. J., Samajdar, A., Sanidas, S. A., Sardesai, S. C., Schmiedekamp, A., Schmiedekamp, C., Schmitz, K., Schult, L., Sesana, A., Shaifullah, G., Shannon, R. M., Shapiro-Albert, B. J., Siemens, X., Simon, J., Singha, J., Siwek, M. S., Speri, L., Spiewak, R., Srivastava, A., Stairs, I. H., Stappers, B. W., Stinebring, D. R., Stovall, K., Sun, J. P., Surnis, M., Susarla, S. C., Susobhanan, A., Swiggum, J. K., Takahashi, K., Tarafdar, P., Taylor, J., Taylor, S. R., Theureau, G., Thrane, E., Thyagarajan, N., Tiburzi, C., Toomey, L., Turner, J. E., Unal, C., Vallisneri, M., van der Wateren, E., van Haasteren, R., Vecchio, A., Krishnan, V. Venkatraman, Verbiest, J. P. W., Vigeland, S. J., Wahl, H. M., Wang, S., Wang, Q., Witt, C. A., Wang, J., Wang, L., Wayt, K. E., Wu, Z., Young, O., Zhang, L., Zhang, S., Zhu, X. -J., and Zic, A.
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Astrophysics - High Energy Astrophysical Phenomena ,General Relativity and Quantum Cosmology - Abstract
The Australian, Chinese, European, Indian, and North American pulsar timing array (PTA) collaborations recently reported, at varying levels, evidence for the presence of a nanohertz gravitational wave background (GWB). Given that each PTA made different choices in modeling their data, we perform a comparison of the GWB and individual pulsar noise parameters across the results reported from the PTAs that constitute the International Pulsar Timing Array (IPTA). We show that despite making different modeling choices, there is no significant difference in the GWB parameters that are measured by the different PTAs, agreeing within $1\sigma$. The pulsar noise parameters are also consistent between different PTAs for the majority of the pulsars included in these analyses. We bridge the differences in modeling choices by adopting a standardized noise model for all pulsars and PTAs, finding that under this model there is a reduction in the tension in the pulsar noise parameters. As part of this reanalysis, we "extended" each PTA's data set by adding extra pulsars that were not timed by that PTA. Under these extensions, we find better constraints on the GWB amplitude and a higher signal-to-noise ratio for the Hellings and Downs correlations. These extensions serve as a prelude to the benefits offered by a full combination of data across all pulsars in the IPTA, i.e., the IPTA's Data Release 3, which will involve not just adding in additional pulsars, but also including data from all three PTAs where any given pulsar is timed by more than as single PTA., Comment: 21 pages, 9 figures, submitted to ApJ
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- 2023
5. The second data release from the European Pulsar Timing Array: IV. Implications for massive black holes, dark matter and the early Universe
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Antoniadis, J., Arumugam, P., Arumugam, S., Auclair, P., Babak, S., Bagchi, M., Nielsen, A. -S. Bak, Barausse, E., Bassa, C. G., Bathula, A., Berthereau, A., Bonetti, M., Bortolas, E., Brook, P. R., Burgay, M., Caballero, R. N., Caprini, C., Chalumeau, A., Champion, D. J., Chanlaridis, S., Chen, S., Cognard, I., Crisostomi, M., Dandapat, S., Deb, D., Desai, S., Desvignes, G., Dhanda-Batra, N., Dwivedi, C., Falxa, M., Fastidio, F., Ferdman, R. D., Franchini, A., Gair, J. R., Goncharov, B., Gopakumar, A., Graikou, E., Grießmeier, J. -M., Gualandris, A., Guillemot, L., Guo, Y. J., Gupta, Y., Hisano, S., Hu, H., Iraci, F., Izquierdo-Villalba, D., Jang, J., Jawor, J., Janssen, G. H., Jessner, A., Joshi, B. C., Kareem, F., Karuppusamy, R., Keane, E. F., Keith, M. J., Kharbanda, D., Khizriev, T., Kikunaga, T., Kolhe, N., Kramer, M., Krishnakumar, M. A., Lackeos, K., Lee, K. J., Liu, K., Liu, Y., Lyne, A. G., McKee, J. W., Maan, Y., Main, R. A., Mickaliger, M. B., Middleton, H., Neronov, A., Nitu, I. C., Nobleson, K., Paladi, A. K., Parthasarathy, A., Perera, B. B. P., Perrodin, D., Petiteau, A., Porayko, N. K., Possenti, A., Prabu, T., Postnov, K., Leclere, H. Quelquejay, Rana, P., Pol, A. Roper, Samajdar, A., Sanidas, S. A., Semikoz, D., Sesana, A., Shaifullah, G., Singha, J., Smarra, C., Speri, L., Spiewak, R., Srivastava, A., Stappers, B. W., Steer, D. A., Surnis, M., Susarla, S. C., Susobhanan, A., Takahashi, K., Tarafdar, P., Theureau, G., Tiburzi, C., Truant, R. J., van der Wateren, E., Valtolina, S., Vecchio, A., Krishnan, V. Venkatraman, Verbiest, J. P. W., Wang, J., Wang, L., and Wu, Z.
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Astrophysics - Cosmology and Nongalactic Astrophysics ,Astrophysics - Astrophysics of Galaxies ,General Relativity and Quantum Cosmology - Abstract
The European Pulsar Timing Array (EPTA) and Indian Pulsar Timing Array (InPTA) collaborations have measured a low-frequency common signal in the combination of their second and first data releases respectively, with the correlation properties of a gravitational wave background (GWB). Such signal may have its origin in a number of physical processes including a cosmic population of inspiralling supermassive black hole binaries (SMBHBs); inflation, phase transitions, cosmic strings and tensor mode generation by non-linear evolution of scalar perturbations in the early Universe; oscillations of the Galactic potential in the presence of ultra-light dark matter (ULDM). At the current stage of emerging evidence, it is impossible to discriminate among the different origins. Therefore, in this paper, we consider each process separately, and investigate the implications of the signal under the hypothesis that it is generated by that specific process. We find that the signal is consistent with a cosmic population of inspiralling SMBHBs, and its relatively high amplitude can be used to place constraints on binary merger timescales and the SMBH-host galaxy scaling relations. If this origin is confirmed, this is the first direct evidence that SMBHBs merge in nature, adding an important observational piece to the puzzle of structure formation and galaxy evolution. As for early Universe processes, the measurement would place tight constraints on the cosmic string tension and on the level of turbulence developed by first-order phase transitions. Other processes would require non-standard scenarios, such as a blue-tilted inflationary spectrum or an excess in the primordial spectrum of scalar perturbations at large wavenumbers. Finally, a ULDM origin of the detected signal is disfavoured, which leads to direct constraints on the abundance of ULDM in our Galaxy., Comment: 30 pages, 23 figures, replaced to match the version published in Astronomy & Astrophysics, note the change in the numbering order in the series (now paper IV)
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- 2023
6. The second data release from the European Pulsar Timing Array V. Search for continuous gravitational wave signals
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Antoniadis, J., Arumugam, P., Arumugam, S., Babak, S., Bagchi, M., Nielsen, A. S. Bak, Bassa, C. G., Bathula, A., Berthereau, A., Bonetti, M., Bortolas, E., Brook, P. R., Burgay, M., Caballero, R. N., Chalumeau, A., Champion, D. J., Chanlaridis, S., Chen, S., Cognard, I., Dandapat, S., Deb, D., Desai, S., Desvignes, G., Dhanda-Batra, N., Dwivedi, C., Falxa, M., Ferranti, I., Ferdman, R. D., Franchini, A., Gair, J. R., Goncharov, B., Gopakumar, A., Graikou, E., Grießmeier, J. M., Guillemot, L., Guo, Y. J., Gupta, Y., Hisano, S., Hu, H., Iraci, F., Izquierdo-Villalba, D., Jang, J., Jawor, J., Janssen, G. H., Jessner, A., Joshi, B. C., Kareem, F., Karuppusamy, R., Keane, E. F., Keith, M. J., Kharbanda, D., Kikunaga, T., Kolhe, N., Kramer, M., Krishnakumar, M. A., Lackeos, K., Lee, K. J., Liu, K., Liu, Y., Lyne, A. G., McKee, J. W., Maan, Y., Main, R. A., Manzini, S., Mickaliger, M. B., Nitu, I. C., Nobleson, K., Paladi, A. K., Parthasarathy, A., Perera, B. B. P., Perrodin, D., Petiteau, A., Porayko, N. K., Possenti, A., Prabu, T., Leclere, H. Quelquejay, Rana, P., Samajdar, A., Sanidas, S. A., Sesana, A., Shaifullah, G., Singha, J., Speri, L., Spiewak, R., Srivastava, A., Stappers, B. W., Surnis, M., Susarla, S. C., Susobhanan, A., Takahashi, K., Tarafdar, P., Theureau, G., Tiburzi, C., van der Wateren, E., Vecchio, A., Krishnan, V. Venkatraman, Verbiest, J. P. W., Wang, J., Wang, L., and Wu, Z.
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Cosmology and Nongalactic Astrophysics ,Astrophysics - Astrophysics of Galaxies ,General Relativity and Quantum Cosmology - Abstract
We present the results of a search for continuous gravitational wave signals (CGWs) in the second data release (DR2) of the European Pulsar Timing Array (EPTA) collaboration. The most significant candidate event from this search has a gravitational wave frequency of 4-5 nHz. Such a signal could be generated by a supermassive black hole binary (SMBHB) in the local Universe. We present the results of a follow-up analysis of this candidate using both Bayesian and frequentist methods. The Bayesian analysis gives a Bayes factor of 4 in favor of the presence of the CGW over a common uncorrelated noise process, while the frequentist analysis estimates the p-value of the candidate to be 1%, also assuming the presence of common uncorrelated red noise. However, comparing a model that includes both a CGW and a gravitational wave background (GWB) to a GWB only, the Bayes factor in favour of the CGW model is only 0.7. Therefore, we cannot conclusively determine the origin of the observed feature, but we cannot rule it out as a CGW source. We present results of simulations that demonstrate that data containing a weak gravitational wave background can be misinterpreted as data including a CGW and vice versa, providing two plausible explanations of the EPTA DR2 data. Further investigations combining data from all PTA collaborations will be needed to reveal the true origin of this feature., Comment: 13 figures, 15 pages, accepted
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- 2023
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7. The second data release from the European Pulsar Timing Array II. Customised pulsar noise models for spatially correlated gravitational waves
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Antoniadis, J., Arumugam, P., Arumugam, S., Babak, S., Bagchi, M., Nielsen, A. S. Bak, Bassa, C. G., Bathula, A., Berthereau, A., Bonetti, M., Bortolas, E., Brook, P. R., Burgay, M., Caballero, R. N., Chalumeau, A., Champion, D. J., Chanlaridis, S., Chen, S., Cognard, I., Dandapat, S., Deb, D., Desai, S., Desvignes, G., Dhanda-Batra, N., Dwivedi, C., Falxa, M., Ferdman, R. D., Franchini, A., Gair, J. R., Goncharov, B., Gopakumar, A., Graikou, E., Grießmeier, J. -M., Guillemot, L., Guo, Y. J., Gupta, Y., Hisano, S., Hu, H., Iraci, F., Izquierdo-Villalba, D., Jang, J., Jawor, J., Janssen, G. H., Jessner, A., Joshi, B. C., Kareem, F., Karuppusamy, R., Keane, E. F., Keith, M. J., Kharbanda, D., Kikunaga, T., Kolhe, N., Kramer, M., Krishnakumar, M. A., Lackeos, K., Lee, K. J., Liu, K., Liu, Y., Lyne, A. G., McKee, J. W., Maan, Y., Main, R. A., Mickaliger, M. B., Niţu, I. C., Nobleson, K., Paladi, A. K., Parthasarathy, A., Perera, B. B. P., Perrodin, D., Petiteau, A., Porayko, N. K., Possenti, A., Prabu, T., Leclere, H. Quelquejay, Rana, P., Samajdar, A., Sanidas, S. A., Sesana, A., Shaifullah, G., Singha, J., Speri, L., Spiewak, R., Srivastava, A., Stappers, B. W., Surnis, M., Susarla, S. C., Susobhanan, A., Takahashi, K., Tarafdar, P., Theureau, G., Tiburzi, C., van der Wateren, E., Vecchio, A., Krishnan, V. Venkatraman, Verbiest, J. P. W., Wang, J., Wang, L., and Wu, Z.
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
The nanohertz gravitational wave background (GWB) is expected to be an aggregate signal of an ensemble of gravitational waves emitted predominantly by a large population of coalescing supermassive black hole binaries in the centres of merging galaxies. Pulsar timing arrays, ensembles of extremely stable pulsars, are the most precise experiments capable of detecting this background. However, the subtle imprints that the GWB induces on pulsar timing data are obscured by many sources of noise. These must be carefully characterized to increase the sensitivity to the GWB. In this paper, we present a novel technique to estimate the optimal number of frequency coefficients for modelling achromatic and chromatic noise and perform model selection. We also incorporate a new model to fit for scattering variations in the pulsar timing package temponest and created realistic simulations of the European Pulsar Timing Array (EPTA) datasets that allowed us to test the efficacy of our noise modelling algorithms. We present an in-depth analysis of the noise properties of 25 millisecond pulsars (MSPs) that form the second data release (DR2) of the EPTA and investigate the effect of incorporating low-frequency data from the Indian PTA collaboration. We use enterprise and temponest packages to compare noise models with those reported with the EPTA DR1. We find that, while in some pulsars we can successfully disentangle chromatic from achromatic noise owing to the wider frequency coverage in DR2, in others the noise models evolve in a more complicated way. We also find evidence of long-term scattering variations in PSR J1600$-$3053. Through our simulations, we identify intrinsic biases in our current noise analysis techniques and discuss their effect on GWB searches. The results presented here directly help improve sensitivity to the GWB and are already being used as part of global PTA efforts., Comment: 20 pages, 6 figures, 9 tables
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- 2023
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8. The second data release from the European Pulsar Timing Array III. Search for gravitational wave signals
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Antoniadis, J., Arumugam, P., Arumugam, S., Babak, S., Bagchi, M., Nielsen, A. -S. Bak, Bassa, C. G., Bathula, A., Berthereau, A., Bonetti, M., Bortolas, E., Brook, P. R., Burgay, M., Caballero, R. N., Chalumeau, A., Champion, D. J., Chanlaridis, S., Chen, S., Cognard, I., Dandapat, S., Deb, D., Desai, S., Desvignes, G., Dhanda-Batra, N., Dwivedi, C., Falxa, M., Ferdman, R. D., Franchini, A., Gair, J. R., Goncharov, B., Gopakumar, A., Graikou, E., Grießmeier, J. -M., Guillemot, L., Guo, Y. J., Gupta, Y., Hisano, S., Hu, H., Iraci, F., Izquierdo-Villalba, D., Jang, J., Jawor, J., Janssen, G. H., Jessner, A., Joshi, B. C., Kareem, F., Karuppusamy, R., Keane, E. F., Keith, M. J., Kharbanda, D., Kikunaga, T., Kolhe, N., Kramer, M., Krishnakumar, M. A., Lackeos, K., Lee, K. J., Liu, K., Liu, Y., Lyne, A. G., McKee, J. W., Maan, Y., Main, R. A., Mickaliger, M. B., Nitu, I. C., Nobleson, K., Paladi, A. K., Parthasarathy, A., Perera, B. B. P., Perrodin, D., Petiteau, A., Porayko, N. K., Possenti, A., Prabu, T., Leclere, H. Quelquejay, Rana, P., Samajdar, A., Sanidas, S. A., Sesana, A., Shaifullah, G., Singha, J., Speri, L., Spiewak, R., Srivastava, A., Stappers, B. W., Surnis, M., Susarla, S. C., Susobhanan, A., Takahashi, K., Tarafdar, P., Theureau, G., Tiburzi, C., van der Wateren, E., Vecchio, A., Krishnan, V. Venkatraman, Verbiest, J. P. W., Wang, J., Wang, L., and Wu, Z.
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Cosmology and Nongalactic Astrophysics ,Astrophysics - Astrophysics of Galaxies - Abstract
We present the results of the search for an isotropic stochastic gravitational wave background (GWB) at nanohertz frequencies using the second data release of the European Pulsar Timing Array (EPTA) for 25 millisecond pulsars and a combination with the first data release of the Indian Pulsar Timing Array (InPTA). We analysed (i) the full 24.7-year EPTA data set, (ii) its 10.3-year subset based on modern observing systems, (iii) the combination of the full data set with the first data release of the InPTA for ten commonly timed millisecond pulsars, and (iv) the combination of the 10.3-year subset with the InPTA data. These combinations allowed us to probe the contributions of instrumental noise and interstellar propagation effects. With the full data set, we find marginal evidence for a GWB, with a Bayes factor of four and a false alarm probability of $4\%$. With the 10.3-year subset, we report evidence for a GWB, with a Bayes factor of $60$ and a false alarm probability of about $0.1\%$ ($\gtrsim 3\sigma$ significance). The addition of the InPTA data yields results that are broadly consistent with the EPTA-only data sets, with the benefit of better noise modelling. Analyses were performed with different data processing pipelines to test the consistency of the results from independent software packages. The inferred spectrum from the latest EPTA data from new generation observing systems is rather uncertain and in mild tension with the common signal measured in the full data set. However, if the spectral index is fixed at 13/3, the two data sets give a similar amplitude of ($2.5\pm0.7)\times10^{-15}$ at a reference frequency of $1\,{\rm yr}^{-1}$. By continuing our detection efforts as part of the International Pulsar Timing Array (IPTA), we expect to be able to improve the measurement of spatial correlations and better characterise this signal in the coming years., Comment: 21 pages, 14 figures, 4 appendix figures, accepted for publication in A&A
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- 2023
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9. Updated guidelines on screening for gestational diabetes
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Gupta Y, Kalra B, Baruah MP, Singla R, and Kalra S
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Gynecology and obstetrics ,RG1-991 - Abstract
Yashdeep Gupta,1 Bharti Kalra,2 Manash P Baruah,3 Rajiv Singla,4 Sanjay Kalra2 1Department of Medicine, Government Medical College and Hospital, Chandigarh, India; 2Bharti Hospital, Karnal, Haryana, India; 3Excel Center, Guwahati, Assam, India; 4Saket City Hospital, New Delhi, India Abstract: Gestational diabetes mellitus (GDM) is associated with an increased risk of complications for both mother and baby during pregnancy as well as in the postpartum period. Screening and identifying these high-risk women is important to improve short- and long-term maternal and fetal outcomes. However, there is a lack of international uniformity in the approach to the screening and diagnosis of GDM. The main purpose of this review is to provide an update on screening for GDM and overt diabetes during pregnancy, and discuss the controversies in this field. We take on debatable issues such as adoption of the new International association of diabetes and pregnancy study groups criteria instead of the Carpenter and Coustan criteria, one-step versus two-step screening, universal screening versus high-risk screening before 24 weeks of gestation for overt diabetes, and, finally, the role of HbA1c as a screening test of GDM. This discussion is followed by a review of recommendations by professional bodies. Certain clinical situations, in which a pragmatic approach is needed, are highlighted to provide a comprehensive overview of the subject. Keywords: pregnancy, guidelines, IADPSG, GDM, Carpenter and Coustan criteria
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- 2015
10. Compensation in Neonatal Clinical Trials: A Perspective
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Mathur, Apoorva, Raja, Dilip, Sinha, Anju, Gupta, Subodh S., Gupta, Y. K., Kawade, Anand S., and Poluru, Ramesh
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- 2024
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11. Precise determination of quadrupole and hexadecapole deformation parameters of the $sd$-shell nucleus, $^{28}$Si
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Gupta, Y. K., Katariy, V. B., Prajapati, G. K., Hagino, K., Patel, D., Ranga, V., Danu, L. S., Pal, A., Joshi, B. N., Dubey, S., Desai, V. V., Panwar, S., Garg, U., Kumar, N., Mukhopadhyay, S., Singh, Pawan, Sirswal, N., Sariyal, R., Mazumdar, I., and John, B. V.
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Nuclear Experiment ,Nuclear Theory - Abstract
Quasi-elastic (QEL) scattering measurements have been performed using $^{28}$Si projectile off a $^{90}$Zr target at energies around the Coulomb barrier. A Bayesian analysis within the framework of coupled channels (CC) calculations is performed in a large parameter space of quadrupole and hexadecapole deformations ($\beta_{2}$ and $\beta_{4}$) of $^{28}$Si. Our results clearly show that $^{28}$Si is an oblate shaped nucleus with $\beta_{2}$=-$0.38 \pm 0.01$ which is in excellent agreement with electromagnetic probes. A precise value of hexadecapole deformation for $^{28}$Si, $\beta_{4}$=+$0.03 \pm 0.01$, along with a consistent value of quadrupole deformation has now been determined for the first time using QEL scattering. A remarkable agreement between the experimental $\beta_{4}$ value of $^{28}$Si and Skyrme-Hartree-Fock based calculations is obtained. The QEL results obtained previously for $^{24}$Mg (prolate) and the present result for $^{28}$Si (oblate) hereby affirm the strong sensitivity of the quasi-elastic scattering to ground state deformations, thus reinforcing its suitability as a potential probe for rare exotic nuclei.
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- 2023
12. Sound speed determination in copper shock compressed to 190 GPa.
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Hawreliak, J. A., Winey, J. M., Toyoda, Y., Zimmerman, K., and Gupta, Y. M.
- Abstract
Sound speed measurements in shock compressed solids have long been valuable for the development of equations of state at extreme conditions, shock-induced phase transformations, and a comprehensive characterization of the thermophysical response of high-pressure standards. We present results from plate impact experiments to 190 GPa to determine the longitudinal sound speed in copper—an important high-pressure standard. Surprisingly, the sound speeds determined using the two most common experimental techniques—the front surface impact (FSI) approach and the release wave overtake (RWO) approach—diverge significantly for stresses greater than ∼100 GPa. Further analyses, including numerical simulations, show that the FSI experiments provide the correct sound speeds and that fundamental assumptions underlying the RWO method are likely violated due to the complex release response of shock compressed copper. The sound speeds determined using the FSI approach provide for a more accurate high-pressure description of copper in dynamic compression experiments. The present findings are in contrast to the results for shock compressed silver [Wallace et al., Phys. Rev. B 104, 214106 (2021)], where both methods provided consistent sound speed results. Thus, the findings presented here demonstrate the need to experimentally verify the validity of the RWO method on a case-by-case basis. Finally, we note that even at the high stresses in the present work, the copper unloading response shows a time-dependent, quasielastic response often observed in metals at lower stresses. [ABSTRACT FROM AUTHOR]
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- 2024
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13. High-Performance Computing for SKA Transient Search: Use of FPGA based Accelerators -- a brief review
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Aafreen, R., Abhishek, R., Ajithkumar, B., Vaidyanathan, Arunkumar M., Barve, Indrajit. V., Bhattramakki, Sahana, Bhat, Shashank, Girish, B. S., Ghalame, Atul, Gupta, Y., Hayatnagarkar, Harshal G., Kamini, P. A., Karastergiou, A., Levin, L., Madhavi, S., Mekhala, M., Mickaliger, M., Mugundhan, V., Naidu, Arun, Oppermann, J., Pandian, B. Arul, Patra, N., Raghunathan, A., Roy, Jayanta, Sethi, Shiv, Shaw, Benjamin, Sherwin, K., Sinnen, O., Sinha, S. K., Srivani, K. S., Stappers, B., Subrahmanya, C. R., Prabu, Thiagaraj, Vinutha, C., Wadadekar, Y. G., Wang, Haomiao, and Williams, C.
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Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
This paper presents the High-Performance computing efforts with FPGA for the accelerated pulsar/transient search for the SKA. Case studies are presented from within SKA and pathfinder telescopes highlighting future opportunities. It reviews the scenario that has shifted from offline processing of the radio telescope data to digitizing several hundreds/thousands of antenna outputs over huge bandwidths, forming several 100s of beams, and processing the data in the SKA real-time pulsar search pipelines. A brief account of the different architectures of the accelerators, primarily the new generation Field Programmable Gate Array-based accelerators, showing their critical roles to achieve high-performance computing and in handling the enormous data volume problems of the SKA is presented here. It also presents the power-performance efficiency of this emerging technology and presents potential future scenarios., Comment: Accepted for publication in the JoAA special issue on SKA (2023)
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- 2022
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14. Upgraded GMRT survey for pulsars in globular clusters. I: Discovery of a millisecond binary pulsar in NGC 6652
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Gautam, T., Ridolfi, A., Freire, P. C. C., Wharton, R. S., Gupta, Y., Ransom, S. M., Oswald, L. S., Kramer, M., and DeCesar, M. E.
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Astrophysics of Galaxies ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Globular clusters contain a unique pulsar population, with many exotic systems that can form only in their dense stellar environments. The leap in sensitivity of the upgraded Giant Metrewave Radio Telescope (uGMRT) in India, especially at low radio frequencies ($<$ 1 GHz) has motivated a new search for radio pulsars in a group of eight Southern globular clusters. We discovered PSR J1835$-$3259B, a 1.83-ms pulsar in NGC 6652; this is in a near-circular wide orbit of 28.7 hr with a low-mass ($ \sim 0.2 \, M_{\rm \odot}$) companion, likely a Helium white dwarf. We derived a 10-year timing solution for this system. We also present measurements of scattering, flux densities and spectral indices for some of the previously known pulsars in these GCs. A significant fraction of the pulsars in these clusters have steep spectral indices. Additionally, we detected eight radio point sources not associated with any known pulsar positions in the radio images. There are four newly identified sources, three in NGC 6652 and one in NGC 6539, and one previously identified source each in NGC 1851, NGC 6440, NGC 6544, and Terzan 5. Surprisingly, our images show that our newly discovered pulsar, PSR J1835$-$3259B, is the brightest pulsar in all GCs we have imaged; like other pulsars with broad profiles (Terzan 5 C and O), its flux density in the radio images is much larger than in its pulsations. This indicates that their pulsed emission is only a fraction of their total emission. The detection of radio sources outside the core radii but well within the tidal radii of these clusters show that future GC surveys should complement the search analysis by using the imaging capability of interferometers, and preferentially synthesize large number of search beams in order to obtain a larger field of view., Comment: 18 pages, 9 figures, 7 tables. Accepted for publication in Astronomy & Astrophysics
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- 2022
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15. Energy dependence of optical potential in the near barrier elastic scattering of 11B from 232Th
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Dubey Shradha, Mukherjee S., Patel D., Gupta Y. K., Danu L. S., Joshi B. N., Prajapati G. K., Mukhopadhyay S., John B. V., Nayak B. K., and Biswas D. C.
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Physics ,QC1-999 - Abstract
The elastic scattering cross sections of 11B projectile on the 232Th target have been measured at different bombarding energies close to the Coulomb barrier. The data has been analyzed for this system using the optical model ECIS code with phenomenological Woods-Saxon forms of the optical potentials. The energy dependence of the volume type real and imaginary parts of the optical potentials are derived from the best fit of the experimental angular distribution data. The total reaction cross sections are obtained from optical model analysis.
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- 2015
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16. Discovery and timing of three millisecond pulsars in radio and gamma-rays with the GMRT and Fermi-LAT
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Bhattacharyya, B., Roy, J., Johnson, T. J., Ray, P. S., Freire, P. C. C., Gupta, Y., Bhattacharya, D., Kaninghat, A., Stappers, B. W., Ferrara, E. C., Sengupta, S., Rathour, R. S., Kerr, M., Smith, D. A., Parkinson, P. M. Saz, Ransom, S. M., and Michelson, P. F.
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
We performed deep observations to search for radio pulsations in the directions of 375 unassociated Fermi Large Area Telescope (LAT) gamma-ray sources using the Giant Metrewave Radio Telescope (GMRT) at 322 and 607 MHz. In this paper we report the discovery of three millisecond pulsars (MSPs), PSR J0248+4230, PSR J1207$-$5050 and PSR J1536$-$4948. We conducted follow up timing observations for around 5 years with the GMRT and derived phase coherent timing models for these MSPs. PSR J0248$+$4230 and J1207$-$5050 are isolated MSPs having periodicities of 2.60 ms and 4.84 ms. PSR J1536-4948 is a 3.07 ms pulsar in a binary system with orbital period of around 62 days about a companion of minimum mass 0.32 solar mass. We also present multi-frequency pulse profiles of these MSPs from the GMRT observations. PSR J1536-4948 is an MSP with an extremely wide pulse profile having multiple components. Using the radio timing ephemeris we subsequently detected gamma-ray pulsations from these three MSPs, confirming them as the sources powering the gamma-ray emission. For PSR J1536-4948 we performed combined radio-gamma-ray timing using around 11.6 years of gamma-ray pulse times of arrivals (TOAs) along with the radio TOAs. PSR J1536-4948 also shows evidence for pulsed gamma-ray emission out to above 25 GeV, confirming earlier associations of this MSP with a >10 GeV point source. The multi-wavelength pulse profiles of all three MSPs offer challenges to models of radio and gamma-ray emission in pulsar magnetospheres., Comment: 35 pages, 8 Figures, 4 Tables, Accepted for publication in the Astrophysical Journal
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- 2021
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17. LOFAR Detection of 110-188 MHz Emission and Frequency-Dependent Activity from FRB 20180916B
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Pleunis, Z., Michilli, D., Bassa, C. G., Hessels, J. W. T., Naidu, A., Andersen, B. C., Chawla, P., Fonseca, E., Gopinath, A., Kaspi, V. M., Kondratiev, V. I., Li, D. Z., Bhardwaj, M., Boyle, P. J., Brar, C., Cassanelli, T., Gupta, Y., Josephy, A., Karuppusamy, R., Keimpema, A., Kirsten, F., Leung, C., Marcote, B., Masui, K., Mckinven, R., Meyers, B. W., Ng, C., Nimmo, K., Paragi, Z., Rahman, M., Scholz, P., Shin, K., Smith, K. M., Stairs, I. H., and Tendulkar, S. P.
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
FRB 20180916B is a well-studied repeating fast radio burst source. Its proximity (~150 Mpc), along with detailed studies of the bursts, have revealed many clues about its nature -- including a 16.3-day periodicity in its activity. Here we report on the detection of 18 bursts using LOFAR at 110-188 MHz, by far the lowest-frequency detections of any FRB to date. Some bursts are seen down to the lowest-observed frequency of 110 MHz, suggesting that their spectra extend even lower. These observations provide an order-of-magnitude stronger constraint on the optical depth due to free-free absorption in the source's local environment. The absence of circular polarization and nearly flat polarization angle curves are consistent with burst properties seen at 300-1700 MHz. Compared with higher frequencies, the larger burst widths (~40-160 ms at 150 MHz) and lower linear polarization fractions are likely due to scattering. We find ~2-3 rad/m^2 variations in the Faraday rotation measure that may be correlated with the activity cycle of the source. We compare the LOFAR burst arrival times to those of 38 previously published and 22 newly detected bursts from the uGMRT (200-450 MHz) and CHIME/FRB (400-800 MHz). Simultaneous observations show 5 CHIME/FRB bursts when no emission is detected by LOFAR. We find that the burst activity is systematically delayed towards lower frequencies by ~3 days from 600 MHz to 150 MHz. We discuss these results in the context of a model in which FRB 20180916B is an interacting binary system featuring a neutron star and high-mass stellar companion., Comment: Accepted for publication by ApJL
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- 2020
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18. Scintillation of PSR B1508+55 -- the view from a 10,000-km baseline
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Marthi, V. R., Simard, D., Main, R. A., Pen, U. -L., van Kerkwijk, M. H., Vanderlinde, K., Gupta, Y., Roberts, C., and Quine, B. M.
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report on the simultaneous Giant Metrewave Radio Telescope (GMRT) and Algonquin Radio Observatory (ARO) observations at 550-750 MHz of the scintillation of PSR B1508+55, resulting in a $\sim$10,000-km baseline. This regime of measurement lies between the shorter few 100-1000~km baselines of earlier multi-station observations and the much longer earth-space baselines. We measure a scintillation cross-correlation coefficient of $0.22$, offset from zero time lag due to a $\sim 45$~s traversal time of the scintillation pattern. The scintillation time of 135~s is $3\times$ longer, ruling out isotropic as well as strictly 1D scattering. Hence, the low cross-correlation coefficient is indicative of highly anisotropic but 2D scattering. The common scintillation detected on the baseline is confined to low delays of $\lesssim 1 \mu$s, suggesting that this correlation may not be associated with the parabolic scintillation arc detected at the GMRT. Detection of pulsed echoes and their direct imaging with the Low Frequency Array (LOFAR) by a different group enable them to measure a distance of 125~pc to the screen causing these echoes. These previous measurements, alongside our observations, lead us to propose that there are at least two scattering screens: the closer 125 pc screen causing the scintillation arc detected at GMRT, and a screen further beyond causing the scintillation detected on the GMRT-ARO baseline. We advance the hypothesis that the 125-pc screen partially resolves the speckle images on the screen beyond leading to loss of coherence in the scintillation dynamic spectrum, to explain the low cross-correlation coefficient., Comment: 10 pages, 8 figures, accepted for publication in MNRAS
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- 2020
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19. Compressional-mode resonances in the molybdenum isotopes: Emergence of softness in open-shell nuclei near A=90
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Howard, K. B., Garg, U., Itoh, M., Akimune, H., Fujiwara, M., Furuno, T., Gupta, Y. K., Harakeh, M. N., Inaba, K., Ishibashi, Y., Karasudani, K., Kawabata, T., Kohda, A., Matsuda, Y., Murata, M., Nakamura, S., Okamoto, J., Ota, S., Piekarewicz, J., Sakaue, A., Senyigit, M., Tsumura, M., and Yang, Y.
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Nuclear Experiment ,Nuclear Theory - Abstract
"Why are the tin isotopes soft?" has remained, for the past decade, an open problem in nuclear structure physics: models which reproduce the isoscalar giant monopole resonance (ISGMR) in the "doubly-closed shell" nuclei, $^{90}$Zr and $^{208}$Pb, overestimate the ISGMR energies of the open-shell tin and cadmium nuclei, by as much as 1 MeV. In an effort to shed some light onto this problem, we present results of detailed studies of the ISGMR in the molybdenum nuclei, with the goal of elucidating where--and how--the softness manifests itself between $^{90}$Zr and the cadmium and tin isotopes. The experiment was conducted using the $^{94,96,98,100}$Mo($\alpha,\alpha^\prime$) reaction at $E_\alpha = 386$ MeV. A comparison of the results with relativistic, self-consistent Random-Phase Approximation calculations indicates that the ISGMR response begins to show softness in the molybdenum isotopes beginning with $A=92$., Comment: Accepted for publication to Physics Letters B
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- 2020
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20. Sensitivity of β4 values extracted from quasi elastic barrier distribution to the 2n transfer channel
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Mohanto, G., Parihari, A., Gupta, Y. K., Pal, A., Gandhi, A., De, Sukanya, Ramachandran, K., Mirgule, E. T., Srinivasan, B., Kalita, K., Kumar, A., Deb, N. K., Rani, K., Tejaswi, A., Vadagama, C., Bharud, Vishal, Danu, L. S., Roy, B. J., Kushwaha, M., Nayak, B. K., and Saxena, A.
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- 2023
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21. A single-laser alternating-frequency magneto-optical trap
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Wiegand, B., Leykauf, B., Döringshoff, K., Gupta, Y. D., Peters, A., and Krutzik, M.
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Physics - Atomic Physics - Abstract
In this paper, we present a technique for magneto-optical cooling and trapping of neutral atoms using a single laser. The alternating-frequency magneto-optical trap (AF-MOT) uses an agile light source that sequentially switches between cooling and repumping transition frequencies by tuning the injection current of the laser diode. We report on the experimental demonstration of such a system for 87Rb and 85Rb based on a micro-integrated extended cavity diode laser (ECDL) performing laser frequency jumps of up to 6.6 GHz with a tuning time in the microsecond regime and a repetition rate of up to 7.6 kHz. For that, a combination of a feed-forward for coarse frequency control and a feedback for precise locking was used. We discuss the results of the AF-MOT characterization in terms of atom numbers and cloud temperature for different operation parameters.
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- 2019
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22. Where we stand on structure dependence of ISGMR in the Zr-Mo region: Implications on K_\infty
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Howard, K. B., Garg, U., Gupta, Y. K., and Harakeh, M. N.
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Nuclear Experiment ,Nuclear Theory - Abstract
Isoscalar giant resonances, being the archetypal forms of collective nuclear behavior, have been studied extensively for decades with the goal of constraining bulk nuclear properties of the equation of state, as well as for modeling dynamical behaviors within stellar environments. An important such mode is the isoscalar electric giant monopole resonance (ISGMR) that can be understood as a radially symmetric density vibration within the saturated nuclear volume. The field has a few key open questions, which have been proposed and remain unresolved. One of the more provocative questions is the extra high-energy strength in the $A\approx 90$ region, which manifested in large percentages of the $E0$ sum rule in $^{92}$Zr and $^{92}$Mo above the main ISGMR peak. The purpose of this article is to introduce these questions within the context of experimental investigations into the phenomena in the zirconium and molybdenum isotopic chains, and to address, via a discussion of previously published and preliminary results, the implications of recent experimental efforts on extraction of the nuclear incompressibility from this data., Comment: 9 pages, 7 figures, invited to be submitted to a special issue of EPJA honoring Prof. P. F. Bortignon
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- 2019
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23. The Expanded Giant Metrewave Radio Telescope
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Patra, N. N., Kanekar, N., Chengalur, J. N., Sharma, R., de Villiers, M., Kumar, B. Ajit, Bhattacharyya, B., Bhalerao, V., Bombale, R., Buch, K. D., Dixit, B., Ghalame, A., Gupta, Y., Hande, P., Hande, S., Hariharan, K., Kale, R., Lokhande, S., Phakatkar, S., Prajapati, A., Rai, S. K., Raybole, P., Roy, J., Shaikh, A. K., and Sureshkumar, S.
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Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
With 30 antennas and a maximum baseline length of 25 km, the Giant Metrewave Radio Telescope (GMRT) is the premier low-frequency radio interferometer today. We have carried out a study of possible expansions of the GMRT, via adding new antennas and installing focal plane arrays (FPAs), to improve its point-source sensitivity, surface brightness sensitivity, angular resolution, field of view, and U-V coverage. We have carried out array configuration studies, aimed at minimizing the number of new GMRT antennas required to obtain a well-behaved synthesized beam over a wide range of angular resolutions for full-synthesis observations. This was done via two approaches, tomographic projection and random sampling, to identify the optimal locations for the new antennas. We report results for the optimal locations of the antennas of an expanded array (the "EGMRT"), consisting of the existing 30 GMRT antennas, 30 new antennas at short distances, $\leq 2.5$ km from the array centre, and 26 new antennas at long distances, $\approx 5-25$ km from the array centre. The collecting area and the field of view of the proposed EGMRT array would be larger by factors of, respectively, $\approx 3$ and $\approx 30$, than those of the GMRT. Indeed, the EGMRT continuum sensitivity and survey speed with 550-850 MHz FPAs installed on the 45 antennas within a distance of $\approx 2.5$ km of the array centre would be far better than those of any existing interferometer, and comparable to the sensitivity and survey speed of Phase-1 of the Square Kilometre Array., Comment: 16 pages, 13 figures; accepted for publication in MNRAS
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- 2019
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24. A phase II study of metformin plus pemetrexed and carboplatin in patients with non-squamous non-small cell lung cancer (METALUNG)
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Verma, S., Chitikela, S., Singh, V., Khurana, S., Pushpam, D., Jain, D., Kumar, S., Gupta, Y., and Malik, P. S.
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- 2023
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25. High-performance computing for SKA transient search: Use of FPGA-based accelerators
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Aafreen, R., Abhishek, R., Ajithkumar, B., Vaidyanathan, Arunkumar M., Barve, Indrajit V., Bhattramakki, Sahana, Bhat, Shashank, Girish, B. S., Ghalame, Atul, Gupta, Y., Hayatnagarkar, Harshal G., Kamini, P. A., Karastergiou, A., Levin, L., Madhavi, S., Mekhala, M., Mickaliger, M., Mugundhan, V., Naidu, Arun, Oppermann, J., Pandian, B. Arul, Patra, N., Raghunathan, A., Roy, Jayanta, Sethi, Shiv, Shaw, B., Sherwin, K., Sinnen, O., Sinha, S. K., Srivani, K. S., Stappers, B., Subrahmanya, C. R., Prabu, Thiagaraj, Vinutha, C., Wadadekar, Y. G., Wang, Haomiao, and Williams, C.
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- 2023
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26. The second data release from the European Pulsar Timing Array: IV. Implications for massive black holes, dark matter, and the early Universe
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Antoniadis, J, Arumugam, P, Arumugam, S, Babak, S, Bagchi, M, Bak Nielsen, A, Bassa, C, Bathula, A, Berthereau, A, Bonetti, M, Bortolas, E, Brook, P, Burgay, M, Caballero, R, Chalumeau, A, Champion, D, Chanlaridis, S, Chen, S, Cognard, I, Dandapat, S, Deb, D, Desai, S, Desvignes, G, Dhanda-Batra, N, Dwivedi, C, Falxa, M, Ferdman, R, Franchini, A, Gair, J, Goncharov, B, Gopakumar, A, Graikou, E, Grießmeier, J, Gualandris, A, Guillemot, L, Guo, Y, Gupta, Y, Hisano, S, Hu, H, Iraci, F, Izquierdo Villalba, D, Jang, J, Jawor, J, Janssen, G, Jessner, A, Joshi, B, Kareem, F, Karuppusamy, R, Keane, E, Keith, M, Kharbanda, D, Kikunaga, T, Kolhe, N, Kramer, M, Krishnakumar, M, Lackeos, K, Lee, K, Liu, K, Liu, Y, Lyne, A, Mckee, J, Maan, Y, Main, R, Mickaliger, M, Niţu, I, Nobleson, K, Paladi, A, Parthasarathy, A, Perera, B, Perrodin, D, Petiteau, A, Porayko, N, Possenti, A, Prabu, T, Quelquejay Leclere, H, Rana, P, Samajdar, A, Sanidas, S, Sesana, A, Shaifullah, G, Singha, J, Speri, L, Spiewak, R, Srivastava, A, Stappers, B, Surnis, M, Susarla, S, Susobhanan, A, Takahashi, K, Tarafdar, P, Theureau, G, Tiburzi, C, Van Der Wateren, E, Vecchio, A, Venkatraman Krishnan, V, Verbiest, J, Wang, J, Wang, L, Wu, Z, Auclair, P, Antoniadis J., Arumugam P., Arumugam S., Babak S., Bagchi M., Bak Nielsen A. S., Bassa C. G., Bathula A., Berthereau A., Bonetti M., Bortolas E., Brook P. R., Burgay M., Caballero R. N., Chalumeau A., Champion D. J., Chanlaridis S., Chen S., Cognard I., Dandapat S., Deb D., Desai S., Desvignes G., Dhanda-Batra N., Dwivedi C., Falxa M., Ferdman R. D., Franchini A., Gair J. R., Goncharov B., Gopakumar A., Graikou E., Grießmeier J. M., Gualandris A., Guillemot L., Guo Y. J., Gupta Y., Hisano S., Hu H., Iraci F., Izquierdo Villalba D., Jang J., Jawor J., Janssen G. H., Jessner A., Joshi B. C., Kareem F., Karuppusamy R., Keane E. F., Keith M. J., Kharbanda D., Kikunaga T., Kolhe N., Kramer M., Krishnakumar M. A., Lackeos K., Lee K. J., Liu K., Liu Y., Lyne A. G., McKee J. W., Maan Y., Main R. A., Mickaliger M. B., Niţu I. C., Nobleson K., Paladi A. K., Parthasarathy A., Perera B. B. P., Perrodin D., Petiteau A., Porayko N. K., Possenti A., Prabu T., Quelquejay Leclere H., Rana P., Samajdar A., Sanidas S. A., Sesana A., Shaifullah G., Singha J., Speri L., Spiewak R., Srivastava A., Stappers B. W., Surnis M., Susarla S. C., Susobhanan A., Takahashi K., Tarafdar P., Theureau G., Tiburzi C., Van Der Wateren E., Vecchio A., Venkatraman Krishnan V., Verbiest J. P. W., Wang J., Wang L., Wu Z., Auclair P., Antoniadis, J, Arumugam, P, Arumugam, S, Babak, S, Bagchi, M, Bak Nielsen, A, Bassa, C, Bathula, A, Berthereau, A, Bonetti, M, Bortolas, E, Brook, P, Burgay, M, Caballero, R, Chalumeau, A, Champion, D, Chanlaridis, S, Chen, S, Cognard, I, Dandapat, S, Deb, D, Desai, S, Desvignes, G, Dhanda-Batra, N, Dwivedi, C, Falxa, M, Ferdman, R, Franchini, A, Gair, J, Goncharov, B, Gopakumar, A, Graikou, E, Grießmeier, J, Gualandris, A, Guillemot, L, Guo, Y, Gupta, Y, Hisano, S, Hu, H, Iraci, F, Izquierdo Villalba, D, Jang, J, Jawor, J, Janssen, G, Jessner, A, Joshi, B, Kareem, F, Karuppusamy, R, Keane, E, Keith, M, Kharbanda, D, Kikunaga, T, Kolhe, N, Kramer, M, Krishnakumar, M, Lackeos, K, Lee, K, Liu, K, Liu, Y, Lyne, A, Mckee, J, Maan, Y, Main, R, Mickaliger, M, Niţu, I, Nobleson, K, Paladi, A, Parthasarathy, A, Perera, B, Perrodin, D, Petiteau, A, Porayko, N, Possenti, A, Prabu, T, Quelquejay Leclere, H, Rana, P, Samajdar, A, Sanidas, S, Sesana, A, Shaifullah, G, Singha, J, Speri, L, Spiewak, R, Srivastava, A, Stappers, B, Surnis, M, Susarla, S, Susobhanan, A, Takahashi, K, Tarafdar, P, Theureau, G, Tiburzi, C, Van Der Wateren, E, Vecchio, A, Venkatraman Krishnan, V, Verbiest, J, Wang, J, Wang, L, Wu, Z, Auclair, P, Antoniadis J., Arumugam P., Arumugam S., Babak S., Bagchi M., Bak Nielsen A. S., Bassa C. G., Bathula A., Berthereau A., Bonetti M., Bortolas E., Brook P. R., Burgay M., Caballero R. N., Chalumeau A., Champion D. J., Chanlaridis S., Chen S., Cognard I., Dandapat S., Deb D., Desai S., Desvignes G., Dhanda-Batra N., Dwivedi C., Falxa M., Ferdman R. D., Franchini A., Gair J. R., Goncharov B., Gopakumar A., Graikou E., Grießmeier J. M., Gualandris A., Guillemot L., Guo Y. J., Gupta Y., Hisano S., Hu H., Iraci F., Izquierdo Villalba D., Jang J., Jawor J., Janssen G. H., Jessner A., Joshi B. C., Kareem F., Karuppusamy R., Keane E. F., Keith M. J., Kharbanda D., Kikunaga T., Kolhe N., Kramer M., Krishnakumar M. A., Lackeos K., Lee K. J., Liu K., Liu Y., Lyne A. G., McKee J. W., Maan Y., Main R. A., Mickaliger M. B., Niţu I. C., Nobleson K., Paladi A. K., Parthasarathy A., Perera B. B. P., Perrodin D., Petiteau A., Porayko N. K., Possenti A., Prabu T., Quelquejay Leclere H., Rana P., Samajdar A., Sanidas S. A., Sesana A., Shaifullah G., Singha J., Speri L., Spiewak R., Srivastava A., Stappers B. W., Surnis M., Susarla S. C., Susobhanan A., Takahashi K., Tarafdar P., Theureau G., Tiburzi C., Van Der Wateren E., Vecchio A., Venkatraman Krishnan V., Verbiest J. P. W., Wang J., Wang L., Wu Z., and Auclair P.
- Abstract
The European Pulsar Timing Array (EPTA) and Indian Pulsar Timing Array (InPTA) collaborations have measured a low-frequency common signal in the combination of their second and first data releases, respectively, with the correlation properties of a gravitational wave background (GWB). Such a signal may have its origin in a number of physical processes including a cosmic population of inspiralling supermassive black hole binaries (SMBHBs); inflation, phase transitions, cosmic strings, and tensor mode generation by the non-linear evolution of scalar perturbations in the early Universe; and oscillations of the Galactic potential in the presence of ultra-light dark matter (ULDM). At the current stage of emerging evidence, it is impossible to discriminate among the different origins. Therefore, for this paper, we consider each process separately, and investigated the implications of the signal under the hypothesis that it is generated by that specific process. We find that the signal is consistent with a cosmic population of inspiralling SMBHBs, and its relatively high amplitude can be used to place constraints on binary merger timescales and the SMBH-host galaxy scaling relations. If this origin is confirmed, this would be the first direct evidence that SMBHBs merge in nature, adding an important observational piece to the puzzle of structure formation and galaxy evolution. As for early Universe processes, the measurement would place tight constraints on the cosmic string tension and on the level of turbulence developed by first-order phase transitions. Other processes would require non-standard scenarios, such as a blue-tilted inflationary spectrum or an excess in the primordial spectrum of scalar perturbations at large wavenumbers. Finally, a ULDM origin of the detected signal is disfavoured, which leads to direct constraints on the abundance of ULDM in our Galaxy.
- Published
- 2024
27. Extended level structure of Cr51 with measured mean lifetimes of yrast states in agreement with shell-model calculations
- Author
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Chakrabarti, R., primary, Mukhopadhyay, S., additional, John, B. V., additional, Biswas, D. C., additional, Tandel, S. K., additional, Danu, L. S., additional, Gupta, Y. K., additional, Joshi, B. N., additional, Prajapati, G. K., additional, Saha, S., additional, Sethi, J., additional, and Palit, R., additional
- Published
- 2024
- Full Text
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28. A blockchain-based approach using smart contracts to develop a smart waste management system
- Author
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Sen Gupta, Y., Mukherjee, S., Dutta, R., and Bhattacharya, S.
- Published
- 2022
- Full Text
- View/download PDF
29. Determination of hexadecapole ($\beta_{4}$) deformation of the light-mass nucleus $^{24}$Mg using quasi-elastic measurement
- Author
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Gupta, Y. K., Nayak, B. K., Garg, U., Sensharma, N., Shahina, Gandhi, R., Biswas, D. C., Şenyiğit, M., Howard, K. B., Tan, W., O'Malley, P. D., Hagino, K., Smith, M., Hall, O., Hall, M., deBoer, Richard J., Ostdiek, K., Liu, Q., Long, A., Hu, J., Anderson, T., Skulski, M., Lu, W., Lamere, E., Lyons, S., Frentz, B., Gyurjinyan, A., Van de Kolk, B., and Seymour, C.
- Subjects
Nuclear Experiment ,Nuclear Theory - Abstract
Quasi-elastic scattering measurements have been performed using $^{16}$O and $^{24}$Mg projectiles off $^{90}$Zr at energies around the Coulomb barrier. Experimental data have been analyzed in the framework of coupled channels (CC) calculations using the code CCFULL. The quasi-elastic scattering excitation function and derived barrier distribution for $^{16}$O + $^{90}$Zr reaction are well reproduced by the CC calculations using the vibrational coupling strengths for $^{90}$Zr reported in the literature. Using these vibrational coupling strengths, a Bayesian analysis is carried out for $^{24}$Mg + $^{90}$Zr reaction. The $\beta_{2}$ and $\beta_{4}$ values for $^{24}$Mg are determined to be $+0.43 \pm 0.02$ and $ - 0.11 \pm 0.02$, respectively. The $\beta_{2}$ parameter determined in the present work is in good agreement with results obtained using inelastic scattering probes. The hexadecapole deformation of $^{24}$Mg has been measured very precisely for the first time. Present results establish that quasi-elastic scattering could provide a useful probe to determine the ground state deformation of atomic nuclei., Comment: This is a slightly modified version, accepted for publication in Phys. Lett. B
- Published
- 2018
30. Isoscalar Giant Monopole, Dipole, and Quadrupole Resonances in $^{90,92}$Zr and $^{92}$Mo
- Author
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Gupta, Y. K., Howard, K. B., Garg, U., Matta, J. T., Senyigit, M., Itoh, M., Ando, S., Aoki, T., Uchiyama, A., Adachi, S., Fujiwara, M., Iwamoto, C., Tamii, A., Akimune, H., Kadono, C., Matsuda, Y., Nakahara, T., Furuno, T., Kawabata, T., Tsumura, M., Harakeh, M. N., and Kalantar-Nayestanaki, N.
- Subjects
Nuclear Experiment ,Nuclear Theory - Abstract
The isoscalar giant monopole, dipole, and quadrupole strength distributions have been deduced in $^{90, 92}$Zr, and $^{92}$Mo from "background-free" spectra of inelastic $\alpha$-particle scattering at a beam energy of 385 MeV at extremely forward angles, including 0$^{\circ}$. These strength distributions were extracted by a multipole-decomposition analysis based on the expected angular distributions of the respective multipoles. All these strength distributions for the three nuclei practically coincide with each other, affirming that giant resonances, being collective phenomena, are not influenced by nuclear shell structure near $A\sim$90, contrary to the claim in a recent measurement., Comment: 12 pages, 12 figures; Accepted for publication in Phys. Rev. C. arXiv admin note: text overlap with arXiv:1607.02198
- Published
- 2018
- Full Text
- View/download PDF
31. Discovery of a radio nebula around PSR J0855-4644
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Maitra, C., Roy, S., Acero, F., and Gupta, Y.
- Subjects
Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report the discovery of a diffuse radio emission around PSR J0855--4644 using an upgraded GMRT (uGMRT) observation at 1.35 GHz. The radio emission is spatially coincident with the diffuse X-ray pulsar wind nebula (PWN) seen with XMM but is much larger in extent compared to the compact axisymmetric PWN seen with Chandra. The morphology of the emission, with a bright partial ring-like structure and two faint tail-like features strongly resembles a bow shock nebula, and indicates a velocity of 100 km/s through the ambient medium. We conclude that the emission is most likely to be associated with the radio PWN of PSR J0855-4644. From the integrated flux density, we estimate the energetics of the PWN., Comment: 4 pages, 2 figures, accepted for publication in MNRAS Letters
- Published
- 2018
- Full Text
- View/download PDF
32. Anisotropic strange stars in Tolman-Kuchowicz spacetime
- Author
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Jasim, M. K., Deb, Debabrata, Ray, Saibal, Gupta, Y. K., and Chowdhury, Sourav Roy
- Subjects
General Relativity and Quantum Cosmology - Abstract
We attempt to study a singularity-free model for the spherically symmetric anisotropic strange stars under Einstein's general theory of relativity by exploiting the Tolman-Kuchowicz metric. Further, we have assumed that the cosmological constant $\Lambda$ is a scalar variable dependent on the spatial coordinate $r$. To describe the strange star candidates we have considered that they are made of strange quark matter (SQM) distribution, which is assumed to be governed by the MIT bag equation of state. To obtain unknown constants of the stellar system we match the interior Tolman-Kuchowicz metric to the exterior modified Schwarzschild metric with the cosmological constant, at the surface of the system. Following Deb et al. we have predicted the exact values of the radii for different strange star candidates based on the observed values of the masses of the stellar objects and the chosen parametric values of the $\Lambda$ as well as the bag constant $\mathcal{B}$. The set of solutions satisfies all the physical requirements to represent strange stars. Interestingly, our study reveals that as the values of the $\Lambda$ and $\mathcal{B}$ increase the anisotropic system becomes gradually smaller in size turning the whole system into a more compact ultra-dense stellar object., Comment: 18 pages, 10 figures
- Published
- 2018
- Full Text
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33. Approach and Experience of IoT Based Predictive Maintenance Technologies in Power Distribution Network
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Sharma, H.C., Gupta, Y. K., Atri, S.K., Singhal, P.K., Bhanage, R.M., Dixit, V. K., and Basu, A.
- Published
- 2022
34. Compact stars with specific mass function
- Author
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Maurya, S. K., Gupta, Y. K., Rahaman, Farook, Rahaman, Monsur, and Banerjee, Ayan
- Subjects
Physics - General Physics - Abstract
Aims: In the present work we search for a new model of compact star within embedding class one spacetime i.e., four dimensional spacetime embedded in five dimensional Pseudo Euclidean space. Methods: In particular we propose a new mass function to obtain an exact analytic solutions of the Einstein field equations. For this specific? mass function, obtained solutions are well-behaved at the centre of the star, satisfy all energy conditions and the mass-radius relation fall within the limit proposed by Buchdahl [1]. Results: The static equilibrium condition has been maintained under different forces. We have discussed the solutions in detail and compare with a set of astrophysical objects like 4U1608-52, PSR J1903+327, PSR J1614-2230 and X-ray pulsar Vela X-1 is also explored., Comment: 21 pages, 23 figures and accepted for publication in Annals of Physics
- Published
- 2017
- Full Text
- View/download PDF
35. Exact solution of anisotropic compact stars via. mass function
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Maurya, S. K., Banerjee, Ayan, and Gupta, Y. K.
- Subjects
Physics - General Physics - Abstract
The interest in studying relativistic compact objects play an important role in modern astrophysics with an aim to understand several astrophysical issues. It is therefore natural to ask for internal structure and physical properties of specific classes of compact star for astrophysical observable, and we obtain a class of new relativistic solutions with anisotropic distribution of matter for compact stars. More specifically, stellar models, described by the anisotropic fluid, establish a relation between metric potentials and generating a specific form of mass function are explicitly constructed within the framework of General Relativity. New solutions that can be used to model compact objects which adequately describe compact strange star candidates like SMC X-1, Her X-1 and 4U 1538-52, with observational data taken from Gangopadhyay et al. [1]. As a possible astrophysical application the obtained solution could explain the physics of self-gravitating objects, might be useful for strong-field regimes where data are currently inadequate., Comment: 10 pages and 15 figures
- Published
- 2017
- Full Text
- View/download PDF
36. Non-linear Dynamic Analysis of a Multi-storey Building Subjected to Earthquakes
- Author
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Verma, Arjit, Pal, P., Gupta, Y. K., di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Pathak, K. K., editor, Bandara, J. M. S. J., editor, and Agrawal, Ramakant, editor
- Published
- 2021
- Full Text
- View/download PDF
37. Approach and Experience of IoT Based Predictive Maintenance Technologies in Power Distribution Network
- Author
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Sharma, H.C., Gupta, Y. K., Atri, S.K., Singhal, P.K., Bhanage, R.M., Dixit, V. K., and Basu, A.
- Published
- 2021
38. Are There Nuclear Structure Effects on the Isoscalar Giant Monopole Resonance and Nuclear Incompressibility near A~90?
- Author
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Gupta, Y. K., Garg, U., Howard, K. B., Matta, J. T., Senyigit, M., Itoh, M., Ando, S., Aoki, T., Uchiyama, A., Adachi, S., Fujiwara, M., Iwamoto, C., Tamii, A, Akimune, H., Kadono, C., Matsuda, Y., Nakahara, T., Furuno, T., Kawabata, T., Tsumura, M., Harakeh, M. N., and Kalantar-Nayestanaki, N.
- Subjects
Nuclear Experiment - Abstract
"Background-free" spectra of inelastic $\alpha$-particle scattering have been measured at a beam energy of 385 MeV in $^{90, 92}$Zr and $^{92}$Mo at extremely forward angles, including 0$^{\circ}$. The ISGMR strength distributions for the three nuclei coincide with each other, establishing clearly that nuclear incompressibility is not influenced by nuclear shell structure near $A\sim$90 as was claimed in recent measurements., Comment: 5 pages, 4 figures; accepted for publication in Phys. Lett. B
- Published
- 2016
- Full Text
- View/download PDF
39. Generalized model for anisotropic compact stars
- Author
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Maurya, S. K., Gupta, Y. K., Ray, Saibal, and Deb, Debabrata
- Subjects
Physics - General Physics - Abstract
In the present investigation an exact generalized model for anisotropic compact stars of embedding class one is sought for under general relativistic background. The generic solutions are verified by exploring different physical aspects, viz. energy conditions, mass-radius relation, stability of the models, in connection to their validity. It is observed that the model present here for compact stars is compatible with all these physical tests and thus physically acceptable as far as the compact star candidates $RXJ~1856-37$, $SAX~J~1808.4-3658~(SS1)$ and $SAX~J~1808.4-3658~(SS2)$ are concerned., Comment: 19 pages, 12 figures, 3 tables
- Published
- 2016
- Full Text
- View/download PDF
40. A new model for spherically symmetric charged compact stars of embedding class one
- Author
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Maurya, S. K., Gupta, Y. K., Ray, Saibal, and Deb, Debabrata
- Subjects
General Relativity and Quantum Cosmology - Abstract
In the present study we search for a new stellar model with spherically symmetric matter and charged distribution under general relativistic framework. The model represents a compact star of embedding class one. The solutions obtain here are general in their nature having the following two features: firstly, the metric becomes flat and also the expressions for the pressure, energy density and electric charge become zero in all the cases if we consider the constant $A=0$, which shows that our solutions represent the so-called `electromagnetic mass model' \cite{Lorentz1904}, and secondly, the metric function $\nu(r)$, for the limit $n$ tends to infinity, converts to $\nu(r)=C{r}^{2}+ ln~B$, which is the same as considered by Maurya et al. \cite{Maurya2015a}. We have investigated several physical aspects of the model and find that all the features are acceptable within the demand of the contemporary theoretical studies and observational evidences., Comment: 18 pages, 8 figures, 5 tables, considerable changes in the text and addition of a new table
- Published
- 2016
- Full Text
- View/download PDF
41. Modelling of anisotropic compact stars of emebedding class one
- Author
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Bhar, Piyali, Maurya, S. K., Gupta, Y. K., and Manna, Tuhina
- Subjects
General Relativity and Quantum Cosmology - Abstract
In the present article, we have constructed static anisotropic compact star models of Einstein field equations for the spherical symmetric metric of embedding class one. By assuming the particular form of metric function $\nu$, We have solved the Einstein field equations for anisotropic matter distribution. The anisotropic models are representing the realistic compact objects such as SAX J 1808.4-3658 (SS1), Her X - 1, Vela X-12, PSR J1614-2230 and Cen X - 3. We have reported our results in details for compact star Her X-1 on the ground of physical properties such as pressure, density, velocity of sound, energy conditions, TOV equation and red-shift etc. Along with these, we have also discussed about stability of the compact star models. Finally we made the comparison between our anisotropic stars with the realistic objects on the key aspects as central density, central pressure, compactness and surface red-shift., Comment: 16 pages, 15 figures and 2 tables, Eur. Phys. J. A (2016) 52: 312
- Published
- 2016
- Full Text
- View/download PDF
42. A new model for spherically symmetric anisotropic compact star
- Author
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Maurya, S. K., Gupta, Y. K., Dayanandan, Baiju, and Ray, Saibal
- Subjects
Physics - General Physics ,General Relativity and Quantum Cosmology - Abstract
In this article we obtain a new anisotropic solution for Einstein's field equation of embedding class one metric. The solution is representing the realistic objects such as $Her~X-1$ and $RXJ~1856-37$. We perform detailed investigation of both objects by solving numerically the Einstein field equations under with anisotropic pressure. The physical features of the parameters depend on the anisotropic factor i.e. if anisotropy is zero everywhere inside the star then the density and pressures will become zero and metric turns out to be flat. We report our results and compare with the above mentioned two compact objects on a number of key aspects: the central density, the surface density onset and the critical scaling behavior, the effective mass and radius ratio, the anisotropization with isotropic initial conditions, adiabatic index and red shift. Along with this we have also made a comparison between the classical limit and theoretical model treatment of the compact objects. Finally we discuss the implications of our findings for the stability condition in relativistic compact star., Comment: 13 pages, 9 figures, 2 tables
- Published
- 2015
- Full Text
- View/download PDF
43. A new exact solution for anisotropic compact stars of embedding class one
- Author
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Maurya, S. K., T., Smitha T., Gupta, Y. K., and Rahaman, Farook
- Subjects
General Relativity and Quantum Cosmology - Abstract
We have presented a new anisotropic solution of Einstein's field equations for compact star models. The Einstein's field equations are solved by using the class one condition \cite{1}. After that we constructed the physically valid expression of anisotropy factor by the help of metric potentials and there after we obtained the physical parameters like energy density, radial and transverse pressure. These models parameters are well behaved inside the compact star and satisfy all the required physical conditions. Also we observed a very interesting result that all the physical parameters are depend on the anisotropy factor. The present compact star models are quite compatible with the observational astrophysical compact stellar objects like Her X-1, RXJ 1856-37, SAX J1808.4-3658(SS1), SAX J1808.4-3658(SS2), Comment: 16 pages, 12 figures and 3 tables in European physical Journal A - 2016
- Published
- 2015
44. Allicin ameliorates aluminium- and copper-induced cognitive dysfunction in Wistar rats: relevance to neuro-inflammation, neurotransmitters and Aβ(1–42) analysis
- Author
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Kaur, Sunpreet, Raj, Khadga, Gupta, Y. K., and Singh, Shamsher
- Published
- 2021
- Full Text
- View/download PDF
45. Approach & experience of iot based predictive maintenance technologies in power distribution network
- Author
-
Sharma, H.C., Gupta, Y. K., Atri, S.K., Singhal, P.K., Bhanage, R.M., Dixit, V. K., and Basu, A.
- Published
- 2021
46. Generalized relativistic anisotropic models for compact stars
- Author
-
Maurya, S. K., Gupta, Y. K., Dayanandan, Baiju, Jasim, M. K., and Al-Jamel, Ahmed
- Subjects
General Relativity and Quantum Cosmology - Abstract
We present new anisotropic generalization of Buchdahl [1] type perfect fluid solution by using the method of earlier work [2]. In similar approach we have constructed the new pressure anisotropy factor ${\Delta}$ by the help both the metric potential $e^{\lambda}$ and $e^{\nu}$. The metric potential $e^{\lambda}$ same as Buchdahl [1] and $e^{\nu}$ is monotonic increasing function as suggested by Lake [3]. After that we obtain new well behaved general solution for anisotropic fluid distribution. We calculated the physical quantities like energy density, radial and tangential pressures, velocity of sound and red-shift etc. We observe that these quantities are positive and finite inside the compact star. Also note that mass and radius of our models can represent the structure of realistic astrophysical objects such as like Her X-1 and RXJ1856-37., Comment: 18 pages, 13 figures (Submitted in Eur. Phys. J. C)
- Published
- 2015
47. Splitting of ISGMR strength in the light-mass nucleus $^{24}$Mg due to ground-state deformation
- Author
-
Gupta, Y. K., Garg, U., Matta, J. T., Patel, D., Peach, T., Hoffman, J., Yoshida, K., Itoh, M., Fujiwara, M., Hara, K., Hashimoto, H., Nakanishi, K., Yosoi, M., Sakaguchi, H., Terashima, S., Kishi, S., Murakami, T., Uchida, M., Yasuda, Y., Akimune, H., Kawabata, T., and Harakeh, M. N.
- Subjects
Nuclear Experiment ,Nuclear Theory - Abstract
The isoscalar giant monopole resonance (ISGMR) strength distribution in $^{24}$Mg has been determined from background-free inelastic scattering of 386-MeV $\alpha$ particles at extreme forward angles, including 0$^{\circ}$. The ISGMR strength distribution has been observed for the first time to have a two-peak structure in a light-mass nucleus. This splitting of ISGMR strength is explained well by microscopic theory in terms of the prolate deformation of the ground state of $^{24}$Mg., Comment: 5 pages, 4 figures; to be published in Phys. Lett. B
- Published
- 2015
48. Relativistic electromagnetic mass models in spherically symmetric spacetime
- Author
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Maurya, S. K., Gupta, Y. K., Ray, Saibal, and Chatterjee, Vikram
- Subjects
General Relativity and Quantum Cosmology - Abstract
Under the static spherically symmetric Einstein-Maxwell spacetime of embedding class one we explore possibility of electromagnetic mass model where mass and other physical parameters have purely electromagnetic origin (Tiwari 1984, Gautreau 1985, Gron 1985). This work is in continuation of our earlier investigation (Maurya 2015a) where we developed an algorithm and found out three new solutions of electromagnetic mass models. In the present letter we consider different metric potentials $\nu$ and $\lambda$ and analyzed them in a systematic way. It is observed that some of the previous solutions related to electromagnetic mass models are nothing but special cases of the presently obtained generalized solution set. We further verify the solution set and show that these are extremely applicable in the case of compact stars as well as for understanding structure of the electron., Comment: 21 pages, 7 figures, 4 tables
- Published
- 2015
- Full Text
- View/download PDF
49. Spherically symmetric electromagnetic mass models of embedding class one
- Author
-
Maurya, S. K., Gupta, Y. K., Ray, Saibal, and Chowdhury, Sourav Roy
- Subjects
General Relativity and Quantum Cosmology - Abstract
In this article we consider the static spherically symmetric spacetime metric of embedding class one. Specifically three new electromagnetic mass models are derived where the solutions are entirely dependent on the electromagnetic field, such that the physical parameters, like density, pressure etc. do vanish for the vanishing charge. We have analyzed schematically all these three sets of solutions related to electromagnetic mass models by plotting graphs and shown that they can pass through all the physical tests performed by us. To validate these special type of solutions related to electromagnetic mass models a comparison has been done with that of compact stars and shown exclusively the feasibility of the models., Comment: 21 pages, 9 figures, 2 tables
- Published
- 2015
50. Anisotropic models for compact stars
- Author
-
Maurya, S. K., Gupta, Y. K., Ray, Saibal, and Dayanandan, Baiju
- Subjects
General Relativity and Quantum Cosmology - Abstract
In the present paper we obtain an anisotropic analogue of Durgapal-Fuloria (1985) perfect fluid solution. The methodology consists of contraction of anisotropic factor $\Delta$ by the help of both metric potentials $e^{\nu}$ and $e^{\lambda}$. Here we consider $e^{\lambda}$ same as Durgapal-Fuloria (1985) whereas $e^{\nu}$ is that given by Lake (2003). The field equations are solved by the change of dependent variable method. The solutions set mathematically thus obtained are compared with the physical properties of some of the compact stars, strange star as well as white dwarf. It is observed that all the expected physical features are available related to stellar fluid distribution which clearly indicate validity of the model., Comment: 18 pages, 13 figures, 4 tables; Published in European Physical Journal C
- Published
- 2015
- Full Text
- View/download PDF
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