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Study of Physical Characteristics of Stellar Configurations

Thesis Info

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Author

Sadiq, Sobia

Program

PhD

Institute

University of the Punjab

City

Lahore

Province

Punjab

Country

Pakistan

Thesis Completing Year

2019

Thesis Completion Status

Completed

Subject

Mathemaics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/9972/1/Sobia%20Sadiq_Maths_19_UoP_punjab_PRR.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727384957

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The aim of this thesis is to study some astrophysical problems in the context of general relativity. Firstly, we investigate the stability of charged anisotropic spheri- cal as well as cylindrical °uid con¯gurations by observing the appearance of crack- ing/overturning within the matter distribution. In case of spherical system, two cases of polytropic relation between density and pressure are taken into account. We employ the perturbations on material variables via polytropic constant as well as polytropic index and construct the corresponding perturbed form of the force distribution func- tion. It is found that the compact object is stable for feasible choice of perturbed polytropic index in the presence of charge. For cylindrically symmetric object, the cracking is explored by applying density perturbations for two models satisfying spe- ci¯c form of Chaplygin equation of state. We conclude that these models experience cracking for larger values of charge. Secondly, we explore exact anisotropic solutions for charged spherical as well as uncharged cylindrical matter distribution through gravitational decoupling approach. In order to ¯nd the solutions, we consider known solution for isotropic °uid and extend it to two types of anisotropic solutions by imposing density as well as pressure constraints. The behavior of physical parameters, energy conditions and stability of the resulting models is also investigated. It is found that only ¯rst solution is physically acceptable as it meets all the energy bounds as well as stability criterion. Finally, we analyze the anisotropic spherical and cylindrical polytropic solutions. For comoving cylindrical system, we formulate the ¯eld equations for three particular forms of gravitational potential and explore exact solutions for di®erent values of the polytropic index. The values of arbitrary constants are determined by taking mass and radius of a well-known compact star (Her X-1). We ¯nd that two of the models are physically reasonable. The spherically symmetric models are constructed for an xii xiii observer moving relative to matter content using two cases of polytropic equation of state under conformally °at condition which aids to ¯nd a speci¯c form of anisotropy parameter. We obtain models numerically and ¯nd that only ¯rst model satis¯es all the energy conditions as well as stability criterion.
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بال جبریل

اس مجموعہ کلام کی غزلیات اور منظومات کسی تخلیقی معجزے سے کم نہیں۔ یہ اقبال کی اردو شاعری کا دوسرا مجموعہ کلام ہے جو جنوری 1935 ء میں منظر عام پر آیا۔ اس میں 1924 ء سے 1934 ء تک کا اردو کلام شامل ہے۔ پہلے ایڈ یشن کی تعداد دس ہزار تھی۔ اس میں مسجد قرطبہ ،ذوق و شوق، ساقی نامہ، لینن خدا کے حضور میں جیسی معروف نظمیں شامل ہیں۔ پروفیسر عبد الحق نے بال جبریل کو اقبال کا " آشوب نامہ “قرار دیا ہے۔ مگر نیا عزم و حوصلہ بھی دکھائی دیتا ہے۔

تفسیر اشاری کی روایت و منہج کا اختصاصی مطالعہ

Tafsir or interpretation of the Quranic scripture has always been a central task for Muslim exegetes. The Tafsir Ishari is a significant genre in the realm of Quranic exegesis that specially explains the inner meanings of theQuranic scripture. The Tafsir ishari is primarily based on the Quranic reading and understanding of the Sufis of the early Islam. This study analyses the argument of scriptural experts concerning the authenticity of this particular type of the Quranic interpretation. Further, it also aims to elucidate the Tafsir Ishari, its tradition and development through presenting an overview of its origin, formation and evolution. It has been argued that the Tafsir Ishari does not have any specific method. As contrast to the literal reading of the Quranic text, the Sufis reflect upon the inner meaning of the Quran and understand the text through spiritual intuition. This research is focused to comprehend various approaches of Sufi interpretations by studying the significant texts of leadingSufi masters i. E. Al-Tustari, Sulami and Ruzbihan al-Baqli. A meticulous effort has been made to ascertain the distinctive methods of Ishari interpretation by analyzing the interpretations of the above mentioned three leading Sufi masters.

Sustainable Management of Aphids on Canola in Organic and Inorganic Farming Systems in Punjab, Pakistan.

Canola (Brassica napus L.) is the second most important source of vegetable oil after soybean. Its oil is widely used in cooking and for making salads and margarines, while the meal is commonly used in animal feeds all around the world. Pakistan, being an agricultural country, is still essentially deficient in edible oil production. It is estimated that more than three fourths of the country’s vegeTable oil requirements are met through imports. Canola is one potential crop which can fulfill the country’s requirement for edible oil. Insect pests are a major yield limiting factor of this crop. Among the insect pests, aphids are considered the major pest. Three aphid species are known to infest the canola crop, the cabbage aphid, Brevicoryne brassicae (L.), the turnip aphid, Lipaphis erysimi Kalt, and the green peach aphid, Myzus persicae (Sulzer) (all are Hemiptera: Aphididae). Heavy aphids attack on canola seedlings can cause wilting of the cotyledons and yellowing of the leaves. Heavy infestations of aphids on pods and flowers lead to yield reductions. Normally aphids cause about 30-35% yield losses on brassica plants but under uncontrolled situations the yield losses may exceed 70%. Control of the pest relies exclusively on pesticides. The indiscriminate use of pesticides has resulted in the development of resistance and resurgence by pests together with associated environmental and health hazards. This situation urgently demands alternate bio-intensive control measures as the main components of an IPM program. The present study was conducted on sustainable management of aphids on canola grown under organic and conventional farming systems in Punjab, Pakistan. The main objective of this study was to develop the most economical and effective management models by determining population distribution of aphids and their natural enemies, screening relatively tolerant crop genotypes, to identify sources of resistance, studying the biology of aphids and determining the efficacy of mechanical, biological and chemical practices for pest suppression. The results of these findings revealed that the cabbage aphids and mustard aphid were found in all four locations studied (Faisalabad, Bahawalpur, Khanpur and D.G. Khan) while the green peach aphid was recorded at two locations (Faisalabad and Khanpur).The genotypes ‘Cyclone’ , ‘Shiralee’ and Oscar were found to be susceptible with maximum population of aphids. The genotypes ‘Hyola-401’ and ‘Rainbow’ were observed to be relatively resistant with lower populations of aphids. The results regarding the biochemical basis of resistance revealed that the availability of nitrogen increases susceptibility, and crop genotypes and farming systems with more nitrogen inputs suffered higher aphid populations. The different evaluated farming systems significantly affected the total life span of aphids, and maximum numbers of nymphs were produced on canola grown under fertilizer applications. All tested insecticides (Carbosulfan, Acetamaprid, Imidacloprid, Nitenpyram and Profenofos) were found to be effective against aphids and reduced population densities. Results revealed that treatments consisting of chrysoperla + coccinellid + blank water spray were highly effective against aphids on canola under both systems of farming. Predators performed well one week after release and their efficacy increased over time. A higher and noticeable yield was obtained under inorganic farming system where Chrysoperla carnea, coccinellids and blank water spray were integrated or blank water spray was applied. However, a higher CBR (10.36:1) was attained under organic (farm yard manure application) where blank water spray was applied on the canola crop. Integration of C. carnea, coccinellids and blank water spray under organic farming system also produced a rationally higher CBR (4.02:1). In conclusion, organic farming system (FYM application) with blank water spray or integration of C. carnea, coccinellids and blank water spray is better option and recommendation for aphid management in canola.