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Hawking Radiation from Some Particular Black Holes

Thesis Info

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Author

Javed, Wajiha

Program

PhD

Institute

University of the Punjab

City

Lahore

Province

Punjab

Country

Pakistan

Thesis Completing Year

2013

Thesis Completion Status

Completed

Subject

Mathemaics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/2315/1/2532S.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726358869

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We first investigate quantum corrections to the thermodynamical quantities (temperature and entropy) for a charged Bardeen and Ay ́n-Beato-Garc ́ o ıa- Bronnikov regular black holes by using a quantum tunneling approach be- yond the semiclassical approximation. It is found that the leading order correction to the entropy is of logarithmic form. We also examine the effects of space noncommutativity on the thermodynamics of a Bardeen charged regular black hole. For a suitable choice of sets of parameters, the behavior of the singularity, horizon, mass function, black hole mass, temperature, entropy and its differential, area and energy distribution of the Bardeen solution is discussed graphically for both noncommutative and commuta- tive spaces. It turns out that the commutative coordinates extrapolate all such quantities (except temperature) for a given set of parameters. It is interesting to mention here that these sets of parameters provide that there is no singularity (essential for r = 0) for the black hole solution both in noncommutative and commutative spaces. We also study the black hole evaporation and Hawking radiation for a noncommutative charged Vaidya black hole. For this purpose, we determine spherically symmetric charged Vaidya model and then formulate a noncom- mutative Reissner-Nordstr ̈m-like solution of this model which leads to an o exact (t − r) dependent metric. The behavior of temporal component of this metric and the corresponding Hawking temperature is investigated. Further, we examine the tunneling process of the charged massive particles through the quantum horizon. It is found that the tunneling amplitude is modified due to noncommutativity. Also, it turns out that black hole evaporates completely in the limits of large time and horizon radius. It is mentioned here that the final stage of black hole evaporation leads to a naked singularity. Finally, we explore Hawking radiation as a tunneling process of charged fermions through event horizons of the charged regular black holes, i.e., Bardeen and ABGB black holes as well as of a pair of charged accelerating and rotating black holes with NUT parameter. We apply the semiclassical WKB approximation to the general covariant Dirac equation of charged par- ticles and evaluate the tunneling probabilities of outgoing charged particles. The Hawking temperature corresponding to these black holes are recovered. We also consider the back-reaction effects of the emitted spin particles from black holes and calculate their corresponding quantum corrections to the radiation spectrum. It is found that this radiation spectrum is not purely thermal due to energy and charge conservation but has some corrections. In the absence of charge and NUT parameter, we find consistent results with those already present in the literature.
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ڈاکٹر ہادی حسن

ڈاکٹر ہادی حسن
افسوس ہے پچھلے دنوں علی گڑھ میں ڈاکٹر ہادی حسن کابھی انتقال ہوگیا۔ مرحوم مسلم یونیورسٹی میں فارسی کے بڑے دیرینہ پروفیسر تھے،انگریزی اورفارسی دونوں زبانوں کے بڑے خوش بیان مقرر اورفارسی شعروادب کے نامور محقق تھے، حافظہ بلاکاتھا ،کسی کتاب کے صفحہ کے صفحہ بلا تکلف اپنی یاد سے پڑھ دیتے تھے۔ مسلم یونیورسٹی کے علاوہ ملک کی دوسری یونیورسٹیوں میں بھی ان کے علم وفضل اور تقریر وخطابت کی دھوم تھی۔ متعدد بلند پایہ کتابوں اورمقالات کے مصنف تھے۔ان کے فیضِ تعلیم وتربیت نے سینکڑوں نوجوانوں کو علم و فن کااستاذ اورماہر بنا دیا۔ بیوی کی وفات اور یونیورسٹی کی ملازمت سے سبکدوش ہونے کے بعد بالکل گوشہ نشین اورزندگی سے بیزار ہوگئے تھے،مگر مطالعہ اور تصنیف وتالیف کا شغل پھر بھی جاری تھا۔خوداُن کاذاتی کتب خانہ بڑی تعداد میں اہم اوربعض نادرالوجودکتابوں پر مشتمل ہے۔اﷲ تعالیٰ مغفرت ورحمت سے نوازے!
[جون۱۹۶۳ء]

 

اسوہ  حسنہ اورمغربی ذہن کے اشکالات.استشراقی فکرکے تناظرمیں تحقیقی و تنقیدی جائزہ

Western mind always remains muddled to fathom the Islamic belief “Prophethood” but it is grand reality that the West has contributed a lot in “Sirah Writing” from 17th to the present age. Although, in primary literature, Western scholars have delineated their abhorrence in this regard, without any research analysis. They usually used to twist the facts and misinterpret the text in attempt to sustain their assumption under their own perception. In the present age, literary change is seen in Western Writings that scholars have admired categorically the demonstrative Personality of Mohammad (PBUH) as well as they have praised his attributes as authoritative leader, Reformer, Peace maker etc. It will discuss the changes which were seen in Western writings about Sirah and analysis the causes and facts accordingly. It will also throw light on the Western assumption about Prophet Muhammad (PBUH); which has been prevailed in their writings before 19th even changed now. Islam is religion of Peace and Prophet of Islam has sent as” Blessing for All the Universe” from God Almighty so the question is what are the motives to bring forward theses western suppositions in this regard and at what extent it will affect? It will be discussed through comparative analysis among the Sirah books by Western Scholars Maxim Rodinson, Karen Armstrong and Michael Cook.

Modulation of Chemotheraphy Resistance Through Hypoxia Inducible Factor-1 Hif-1 Inhibition

Cancer is one the leading reason of mortality worldwide. Resistance to chemotherapy i.e. ‘chemotherapy resistance’ shares the bulk of cancer related mortality. This resistance is mediated by many cellular pathway alterations, ensuing cellular hypoxia being one of the well-known factors. The hypoxic mechanism is driven by various genetic signatures, the most notable among which is hypoxia inducible factor-1α (HIF-1α) which regulates transcription of many genes to promote cancer cell survival, and progression. Multidrug resistance gene-1 (MDR1) and Lysosome-associated protein transmembrane 4B-35 (LAPTM4B-35) are among those notable players which augment their responses to cellular hypoxia. Therefore, pharmacological inhibition of HIF-1 by disrupting its dimerization can be a key strategy to overcome therapy resistance primarily and arresting tumor growth and progression secondarily. This thesis dissertation suggests potential HIF1 dimerization inhibitors constructed through ligand- and structure-based pharmacophore modelling with rigorous virtual database screening. The shortlisted hits then underwent cell line testing under hypoxic conditions for validation of HIF1 inhibition and inhibition of down-stream HIF1 effector gene VEGF and GLUT1.The current work also studied coexpression of hypoxia driven genes HIF-1α, MDR1 and LAPTM4B in peripheral blood lymphocytes of chemotherapy receiving 72 breast, 42 ovarian, 32 colon and 21 prostate cancer patients with reference to their correlation of clinic-pathologic parameters. The current work also proposed structural determinants of LAPTM4B gene computationally for its potential functionality and interaction with cellular proteins of PI3-AKT pathway involved in mediating chemotherapy resistance. The results from the computational and in-vitro validation by western blot analysis identified compound 2 and compound 6 to be effectively disrupting dimerization with concentration of 18.4±14.5 and 274±53.5 µM respectively.The co-expression of HIF-1α, MDR1 and LAPTM4B has been statistically scrutinized via Fisher’s Exact test and the Spearman correlation method. The expression analysis suggested 12–13 folds’ increase in expression of HIF-1α, 2-fold increase in MDR1 and 13–14 fold increase in LAPTM4B mRNA level in peripheral blood of breast, ovarian, prostate and colon cancer patients. In the current study there was an association of HIF-1α, MDR1 and LAPTM4B expression Abstract 2 with advanced tumor stage, metastasis and chemotherapy treated group in breast, ovarian, prostate and colon cancer patients. The Spearman analysis also revealed a positive linear association among HIF-1α, MDR1 and LAPTM4B in all the studied cancer patients. The results from LAPTM4B structural characterization and interaction revealed LAPTM4B interaction with P85α (regulatory domain of PI3K) through its PPRP motif while it interacts with NEDD4 through its PY domain. The important positional interactions are Arg26:LAPTM4B and Glu52:P85α, Arg90:LAPTM4B and Asp21:P85α, Leu348:LAPTM4B and Gly421:NEDD4, Glu362, Tyr351:LAPTM4B and Arg430:NEDD4. The current thesis work proposed potential HIF-1 inhibitors which can be structurally optimized for efficacy, selectivity, pharmacokinetic and toxicity profiling before clinical investigations. The elevated expression of HIF-1α, MDR1 and LAPTM4B in peripheral blood of solid tumor patients can be a predictor of metastasis, disease progression and treatment response in cancers. These interactions of LAPTM4B can aid in drug targeting to design novel LAPTM4B inhibitors.