Browsing by Author "Abha Singh"

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1/fα noise in the Robin Hood model
(Institute of Physics, 2024) Abha Singh; Rahul Chhimpa; Avinash Chand Yadav
We consider the Robin Hood dynamics, a one-dimensional extremal self-organized critical model that describes the low-temperature creep phenomenon. One of the key quantities is the time evolution of the state variable (force noise). To understand the temporal correlations, we compute the power spectra of the local force fluctuations and apply finite-size scaling to get scaling functions and critical exponents. We find a signature of the 1 / f α noise for the local force with a nontrivial value of the spectral exponent 0 < α < 2 . We also examine temporal fluctuations in the position of the extremal site and a local activity signal. We present results for different local interaction rules of the model. © 2024 IOP Publishing Ltd and SISSA Medialab srl. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
A case report on anaesthetic challenges in Patau syndrome: Navigating craniofacial and cardiac defects
(IP Innovative Publication Pvt. Ltd., 2023) Abha Singh; Pragya Shukla; Amrita Rath; Shashi Prakash; Sanjay Bhaskar
The anaesthetic management of paediatric patients with Patau syndrome presents unique challenges, particularly when combined with craniofacial and cardiac defects and limited airway resources. This case report highlights our experience in managing a syndromic child with a difficult airway in a resource-constrained environment. The inability to secure the airway adequately can pose significant perioperative risks. In this case, we successfully utilized an oesophageal bougie as an alternative technique to secure the airway. This report emphasizes the importance of adapting to limited resources and employing innovative approaches to ensure optimal patient care in challenging situations. © 2023 Author(s), Published by Innovative Publication.
A Laryngeal web with tracheo-esophageal fistula: Anaesthesiologist skating on a thin ice; [Trakeo-ozofageal fistullu bir laringeal web: ince bir buz uzerinde paten yapan anestezist]
(Anestezi Dergisi, 2022) Amrita Rath; Abha Singh; Reena; Pragya Shukla; Sarita Choudhary; Shiv Prasad Sharma; Kairi Dibo
Tracheo-esophageal fistula (TEF) in association with subglottic laryngeal web is a rare entity. Often the diagnosis of laryngeal web in the presence of TEF is missed and it is identified during intubation attempts. The triad of neonatal age, TEF and laryngeal web can even cause the most experienced anaesthetists concern about the mortality and morbidity that may develop due to the inability to secure the airway. In this case report, we aimed to share our experience on the airway management of a newborn with laryngeal web. © 2022 Anestezi Dergisi. All rights reserved.
Association of solar flares with magnetic complexity of the sunspot groups in solar active regions during solar cycles 23–25
(Springer, 2024) Anurag Chaudhari; Abha Singh; Gyaneshwar Sharma; Abhay Kumar Singh
The present study aims to investigate the association of X-ray solar flares with the magnetic complexity of sunspot groups in active regions for the period from 1996 to 2023 (solar cycles 23 to 24 and ascending phase of solar cycle 25). Statistically, we have found that (1) the total 37,166 sunspots are affiliated with the 5412 active regions. Following the Hale magnetic complexity categorization method, a total occurring sunspot groups, comprised of 31.01% α, 57.13% β, 0.01% γ, 0% δ, 0.027% γδ, 0.54% βδ, 8.45% βγ, and 2.83% βγδ magnetic groups. (2) We also found that a total of 44,667 solar flares were observed in selected time intervals. Out of that total of 44,667 solar flares, only 24,031 (60.40%) flares have their solar active region, remaining flares have an unknown solar origin. Further investigation also shows that, out of 24,031 solar flares only 23,531 solar flares are associated with sunspot groups of different magnetic complexity (according to Hale magnetic classification). These sunspot groups are affiliated with the 2499 active regions. The investigated flares (sunspot-associated) database consists of 34.11% B-, 57.87% C-, 7.36% M-, and 0.63% X-class flares. Finally, we found that a higher percentage of the intense flares (M- and X-Class) are associated with the βγδ type sunspot groups in solar cycles 23 and 24. We also observed that maximum X-class flares are associated with βγδ sunspot groups during the peak of solar cycles 23 and 24. Whereas maximum B- and C-class flares are associated with β sunspot groups during the ascending phase of each solar cycle. © Indian Association for the Cultivation of Science 2024.
Causes responsible for intense and severe storms during the declining phase of Solar Cycle 24
(Springer, 2019) Kalpana Patel; Abha Singh; S.B. Singh; A.K. Singh
The occurrence of total 113 geomagnetic storms during declining phase of Solar Cycle 24 (2015–2017) subdivided as about 105 moderate storms (Dst=-50nT to - 100 nT), 6 intense storms (Dst=-100nT to - 200 nT) and 2 severe storms (Dst<-200nT) has been diagnosed on the basis of 5 day active window through the CACTus (Computer aided CME tracking) software. A detailed study has been carried out for the 6 intense and 2 severe storms. It is inferred that CMEs are the major source of geomagnetic storms to occur. Out of the 6 intense and 2 severe storms, only 1 has been observed with the origin of CIR. Thus, all analyzed intense geomagnetic storms are due to coronal mass ejection at the Sun. Most of our results are in good accordance with other reported results. © 2019, Indian Academy of Sciences.
Effect of intense geomagnetic storms on low-latitude TEC during the ascending phase of the solar cycle 24
(Springer, 2021) Abha Singh; Vishnu S. Rathore; Sanjay Kumar; S.S. Rao; Sudesh K. Singh; A.K. Singh
The results presented in this paper are obtained from low-latitude ionospheric total electron content (TEC) variation during the chosen geomagnetic storm events happening during the solar cycle 24. We include the four intense geomagnetic storms that occurred on 26 September 2011, 15 July 2012, 19 February 2014 and 20 December 2015, depending upon the availability of TEC data. For this, we have used the TEC data from low-latitude station Varanasi (geographic latitude 25°, 16′N, geographic longitude 82°, 59′E and geomagnetic latitude 16°, 24′N) and an equatorial station Bengaluru (geographic latitude 13°, 02′N, geographic longitude 77°, 34′E and geomagnetic latitude 04°, 68′N). The storm-induced TEC changes at chosen stations have been discussed in terms of local time, storm wind effect, neutral wind, composition changes and variation in the dawn–dusk component of the interplanetary electric field (IEF Ey). © 2021, Indian Academy of Sciences.
Effect of intense solar flares on TEC variation at low-latitude station Varanasi
(Springer, 2020) Abha Singh; S.S. Rao; V.S. Rathore; Sudesh K. Singh; A.K. Singh
The effect of intense solar flares on total electron content (TEC) variability during the declining phase of solar cycle-24 is studied at the low-latitude station at Varanasi, India (Geog. Lat. 25.31° N, Geog. Long. 82.97° E, Geomag. Lat. 16.54° N, Geomag. Long. 157.09° E). In the present paper, we have chosen the intense solar flares that occurred during 9–13 March 2015, 1–2 January 2016, 12–14 February 2016, 6–8 August 2016, and 6–8 September 2017 in the solar cycle-24 period for which the data is available. Our results showed significant enhancements in TEC up to the order of 15 TECU during and after the solar flare events. We have also given a brief account of solar flare effect in TEC with and without geomagnetic disturbances, local time effects (solar zenith angle effects) and changing the location of the solar active region. In a few cases, our results revealed a delay in TEC response during the flare peak time as well as recovery time. © 2020, Indian Academy of Sciences.
Fitness fluctuations in the Bak-Sneppen model
(American Physical Society, 2023) Abha Singh; Rahul Chhimpa; Avinash Chand Yadav
We study the one-dimensional Bak-Sneppen model for the evolution of species in an ecosystem. Of particular interest are the temporal fluctuations in fitness variables. We numerically compute the power spectral density and apply the finite-size scaling method to get data collapse. A clear signature of 1/fα noise with α≈1.2 (long-time correlations) emerges for both local and global (or average) fitness noises. The limiting value of the spectral exponent, 0 or 2, corresponds to no interaction or a random neighbor version of the model, respectively. The local power spectra are spatially uncorrelated and also show an additional scaling, ∼1/L, in the frequency regime L-λf1/2, where L is the linear extent of the system. © 2023 American Physical Society.
Fitness noise in the Bak-Sneppen evolution model in high dimensions
(American Physical Society, 2024) Rahul Chhimpa; Abha Singh; Avinash Chand Yadav
We study the Bak-Sneppen evolution model on a regular hypercubic lattice in high dimensions. Recent work [Phys. Rev. E 108, 044109 (2023)2470-004510.1103/PhysRevE.108.044109] showed the emergence of the 1/fα noise for the fitness observable with α≈1.2 in one-dimension (1D) and α≈2 for the random neighbor (mean-field) version of the model. We examine the temporal correlation of fitness in 2, 3, 4, and 5 dimensions. As obtained by finite-size scaling, the spectral exponent tends to take the mean-field value at the upper critical dimension Du=4, which is consistent with previous studies. Our approach provides an alternative way to understand the upper critical dimension of the model. We also show the local activity power spectra, which offer insight into the return time statistics and the avalanche dimension. © 2024 American Physical Society.
Inactivation of cyanobacterial nitrogenase after exposure to ultraviolet-B radiation
(2003) Ashok Kumar; Madhu Bala Tyagi; Prabhat Nath Jha; Gannavarapu Srinivas; Abha Singh
Exposure of the N2-fixing cyanobacterium Anabaena BT2 to ultraviolet-B radiation (2.5 W m-2) for 30 min resulted in complete loss of nitrogenase activity but 100% cell killing occurred only after a 90-min exposure. Inactivation of nitrogenase activity was not specific to Anabaena BT2; other species also showed a similar effect. The time required for 100% killing and inactivation of nitrogenase activity differed in various species, and this difference may be ascribed to the presence of different levels of UV-B protection mechanisms in individual species. Inhibition of nitrogenase activity was immediate, since exposure of cultures to UV-B for as little as 5 min elicited some inhibition of activity. The activity of UV-B-inhibited nitrogenase did not recover upon transfer of exposed cells to fluorescent light, suggesting that the inhibition may be due to specific inactivation of the enzyme. By employment of inhibitors of protein synthesis and PS-II activity, it was demonstrated that restoration of nitrogenase activity in a UV-B-treated culture occurred by fresh synthesis of nitrogenase polypeptide. Our findings suggest that estimation of nitrogenase activity in diazotrophic species may be used as a marker enzyme for assessing the impact of UV-B radiation.
Shamrock fetus in fetu: An anesthetic enigma
(Elsevier B.V., 2025) Amrita Rath; Abha Singh; Reena; Ritwik Mohan; M. Rajesh; Rajat Arora; Ruchira Nandan
Fetus in fetu (FIF) is a rare congenital anomaly with an incidence of 1 in 5 lakh live births. Till date, only 200 cases have been reported, with the majority having a single FIF. We report an interesting case of FIF with 3 interlinked fetuses inside giving the appearance of Shamrock leaf. The FIF was causing compression of the common bile duct causing obstructive jaundice as well as was associated with moderate hydronephrosis, presenting unique anesthetic challenges. Our purpose to write this case report was to add to the existing knowledge of this rare entity besides discussing its anesthetic implications. © 2024
Shamrock fetus in fetu: An anesthetic enigma
(Elsevier B.V., 2024) Amrita Rath; Abha Singh; Reena; Ritwik Mohan; M. Rajesh; Rajat Arora; Ruchira Nandan
Fetus in fetu (FIF) is a rare congenital anomaly with an incidence of 1 in 5 lakh live births. Till date, only 200 cases have been reported, with the majority having a single FIF. We report an interesting case of FIF with 3 interlinked fetuses inside giving the appearance of Shamrock leaf. The FIF was causing compression of the common bile duct causing obstructive jaundice as well as was associated with moderate hydronephrosis, presenting unique anesthetic challenges. Our purpose to write this case report was to add to the existing knowledge of this rare entity besides discussing its anesthetic implications. © 2024
Source identification of moderate (−100 nT < Dst < −50 nT) and intense geomagnetic storms (Dst < −100 nT) during ascending phase of solar cycle 24
(Elsevier Ltd, 2017) Abha Singh; V.S. Rathore; R.P. Singh; A.K. Singh
The origin of 39 moderate (−100 nT < Dst < −50 nT) and 12 intense (Dst < −100 nT) geomagnetic storms has been investigated using fixed time window and adoptive time window. Coronal mass ejections (CMEs) and corotating interaction region (CIR) are found to be the primary sources. Out of 12 intense geomagnetic storms, 6 (50%) events are associated with unique FSH CMEs, 2 (17%) events with multiple FSH CMEs, 3 events (25%) with partial halo CME with no surface signature and 1 event (8%) is caused due to a CIR. Out of 39 moderate geomagnetic storms 21 (54%) are associated with full halo CME and 5 (13%) with partial halo CME, 4 (10%) storms associated with high speed solar wind from CIR whereas 1 storm has been found to be due to the combined effect of CME and CIR. The remaining 8 (20%) storms have unknown solar origins and were mostly observed when solar activity was at the minimum. The probability of a CIR causing a moderate storm is almost double as compared to an intense storm during the ascending phase of weak solar cycle 24. © 2016 COSPAR
Variation in the Flaring Potential of Different Sunspot Groups During Different Phases of Solar Cycles 23 and 24
(Institute of Physics, 2024) Abha Singh; Anurag Chaudhari; Gyaneshwar Sharma; A.K. Singh
In this present study, we have analyzed different types of X-ray solar flares (C, M, and X classes) coming out from different classes of sunspot groups (SSGs). The data which we have taken under this study cover the duration of 24 yr from 1996 to 2019. During this, we observed a total of 15015 flares (8417 in SC-23 and 6598 in SC-24) emitted from a total of 33780 active regions (21746 in SC-23 and 12034 in SC-24) with sunspot only. We defined the flaring potential or flare-production potential as the ratio of the total number of flares produced from a particular type of SSG to the total number of the same-class SSGs observed on the solar surface. Here we studied yearly changes in the flaring potential of different McIntosh class groups of sunspots in different phases of SC-23 and 24. In addition, we investigated yearly variations in the potential of producing flares by different SSGs (A, B, C, D, E, F, and H) during different phases (ascending, maximum, descending, and minimum) of SC-23 and 24. These are our findings: (1) D, E, and F SSGs have the potential of producing flares ≥8 times greater than A, B, C and H SSGs; (2) The larger and more complex D, E, and F SSGs produced nearly 80% of flares in SC-23 and 24; (3) The A, B, C and H SSGs, which are smaller and simpler, produced only 20% of flares in SC-23 and 24; (4) The biggest and most complex SSGs of F-class have flaring potential 1.996 and 3.443 per SSG in SC-23 and 24, respectively. (5) The potential for producing flares in each SSG is higher in SC-24 than in SC-23, although SC-24 is a weaker cycle than SC-23. (6) The alterations in the number of flares (C+M+X) show different time profiles than the alterations in sunspot numbers during SC-23 and 24, with several peaks. (7) The SSGs of C, D, E, and H-class have the highest flaring potential in the descending phase of both SC-23 and 24. (8) F-class SSGs have the highest flaring potential in the descending phase of SC-23 but also in the maximum phase of SC-24. © 2024. National Astronomical Observatories, CAS and IOP Publishing Ltd.