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10. Viscous effects on nonlinear double tearing mode and plasmoid formation in adjacent Harris sheets

Author

Ahmad, Nisar, Zhu, Ping, Shen, Chao, Ali, Ahmad, and Zeng, Shiyong

Subjects
Physics - Plasma Physics
Abstract

In this paper, we study the effects of viscosity on the evolution of double tearing mode (DTM) in a pair of adjacent Harris sheets based on the resistive MHD model in the NIMROD code. Similar to the tearing mode in the conventional single Harris sheet, a transition is observed in the generation of both normal and monster plasmoids at Pr = 1. In the Pr < 1 regime of DTM, normal plasmoids (small plasmoids) are generated along with monster plasmoid, whereas in the single tearing mode (STM) cases such a generation is not observed. When Pr is above the critical value, the generation of monster plasmoid is halted. Correspondingly, in the Pr < 1 regime, a quadrupolar flow advects along poloidal direction, but in Pr > 1 regime this flow advection is inhibited.

Published
2022

13. Neonatal adrenal hemorrhage presenting as late onset neonatal jaundice

Author

Qureshi Umar, Ahmad Nisar, Rasool Akhter, and Choh Suhail

Subjects
Adrenal, jaundice, neonatal hemorrhage, Pediatrics, RJ1-570, Surgery, RD1-811
Abstract

Clinical manifestations of adrenal hemorrhage vary depending on the degree and rate of hemorrhage, as well as the amount of adrenal cortex compromised by hemorrhage. We report here a case of neonatal adrenal hemorrhage that presented with late onset neonatal jaundice. The cause of adrenal hemorrhage was birth asphyxia.

Published
2009

19. Viscous effects on plasmoid formation from nonlinear resistive tearing growth in a Harris sheet

Author

Ahmad, Nisar, Zhu, Ping, Ali, Ahmad, and Zeng, Shiyong

Subjects
Physics - Plasma Physics
Abstract

In this study, the evolution of a highly unstable m = 1 resistive tearing mode, leading to plasmoid formation in a Harris sheet is studied in the framework of full MHD model using the NIMROD simulation. Following the initial nonlinear growth of the primary m = 1 island, the X-point develops into a secondary elongated current sheet that eventually breaks into plasmoids. Two distinctive viscous regimes are found for the plasmoid formation and saturation. In the low viscosity regime (i.e. P r . 1), the plasmoid width increases sharply with viscosity, whereas in the viscosity dominant regime (i.e. P r & 1 ), the plasmoid size gradually decreases with viscosity. Such a finding quantifies the role of viscosity in modulating the plasmoid formation process through its effects on the plasma flow and the reconnection itself.

Published
2021
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22. Advanced Biotechnological Tools for Improving Phosphorus Use Efficiency

Author

Malik, Hafiza Aasia, Rahman, Atta Ur, Akbar, Fazal, Ahmad, Nisar, Ali, Syed Shujait, Suleman, Muhammad, Ali, Shahid, Hussain, Zahid, Zaman, Nasib, Rasool, Akhtar, Shah, Muzafar, Israr, Muhammad, Iqbal, Asif, Lichtfouse, Eric, Series Editor, Ranjan, Shivendu, Advisory Editor, Dasgupta, Nandita, Advisory Editor, Iqbal, Asif, editor, Iqbal, Mazhar, editor, Alamzeb, Madeeha, editor, Meizhen, Song, editor, Xiling, Zhang, editor, Arif, Muhammad, editor, and Du, Xiongming, editor

Published
2023
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31. Authors′ reply

Author

Qureshi Umar, Ahmad Nisar, Rasool Akhter, and Choh Suhail

Subjects
Pediatrics, RJ1-570, Surgery, RD1-811
Published
2010

44. Dose Verification of Volumetric Modulated Arc Therapy using One and Two Dimensional Dosimeters

Author

Rehman, Jalil ur, Zahra, Hussain, Ghulam, Ahmad, Nisar, Asghar, H M Noor ul Huda Khan, Gilani, Zaheer Abbas, Nasar, Gulfam, Akhter, Malik M, Isa, Muhammad, and Ibbott, Geoffrey S.

Subjects
Physics - Medical Physics
Abstract

Purpose: To verify dose delivery and quality assurance of volumetric modulated arc therapy (VMAT) for head and neck cancer. Method: The Imaging and Radiation Oncology Core Houston (IROC-H) head and neck phantom with thermo- luminescent dosimeters (TLDs) and films, were imaged with computed tomography scan and the reconstructed image was transferred to pinnacle treatment planning system (TPS). On TPS the planning target volume (PTV), secondary target volume (STV) and organ at risk (OAR) were delineated manually and a treatment plan was made. The dose constraints were determined for the concerned organs according to IROC-H prescription. The treatment plan was optimized using adoptive convolution algorithm to improve dose homogeneity and conformity. The dose calculation was performed using C.C Convolution algorithm and a Varian True Beam linear accelerator was used to deliver the treatment plan to the head and neck phantom. The delivered radiation dose to the phantom was measured through TLDs and GafChromic EBT2 films. The dosimetric performance of the VMAT delivery was studied by analysing percent dose difference, iso-dose line profile and gamma analysis of the TPS computed dose and linac delivered doses. Result: the percent dose difference of 3.8\% was observed between the planned and measured doses of TLDs and a 1.5mm distance to agreement (DTA) was observed by comparing iso-dose line profiles. Passed the gamma criteria of 3\%/3 mm was with good percentages. Conclusion: The dosimetric performance of VMAT delivery for a challenging head and neck radiotherapy can be verified using TLDs and films imbedded in an anthropomorphic H\&N phantom., Comment: 12 pages, 4 figures

Published
2018

45. Advanced Biotechnological Tools for Improving Phosphorus Use Efficiency

Author

Malik, Hafiza Aasia, primary, Rahman, Atta Ur, additional, Akbar, Fazal, additional, Ahmad, Nisar, additional, Ali, Syed Shujait, additional, Suleman, Muhammad, additional, Ali, Shahid, additional, Hussain, Zahid, additional, Zaman, Nasib, additional, Rasool, Akhtar, additional, Shah, Muzafar, additional, Israr, Muhammad, additional, and Iqbal, Asif, additional

Published
2022
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