Greybody factor of scalar fields from black strings

The greybody factor of massless, uncharged scalar fields is studied in the background of cylindrically symmetric spacetimes, in the low-energy approximation. We discuss two cases. In the first case we derive analytical expression for the absorption probability when the spacetime is kinetically coupled with the Einstein tensor. In the second case we do the analysis in the absence of the coupling constant. For this purpose we analyze the wave equation which is obtained from Klein-Gordon equation. The radial part of the wave equation is solved in the form of the hypergeometric function in the near horizon region, whereas in the far region the solution is of the form of Bessel's function. Finally, considering continuity of the wave function we smoothly match the two solutions in the low energy approximation to get the formula for the absorption probability

State Controlled Object Oriented Programming

In this thesis, we examine an extension to the idea of object oriented programming to make programs easier for people and compilers to understand. Often objects behave differently depending on the history of past operations as well as their input that is their behavior depends on state. We may think of the fields of an object as encoding two kinds of information: data that makes up the useful information in the object and state that controls its behavior. Object oriented languages do not distinguish these two. We propose that by specifying these two, programs become clearer for people to write and understand and easier for machines to transform and optimize. We introduce the notion of state controlled object oriented programming, abbreviated as “SCOOP”, which encompasses explicit support of state in objects. While introducing an extension to object oriented programming, our objective is to minimize any burden on the programmer while programming with SCOOP. Static detection of the current state of an object by programming languages has been a challenge. To overcome this challenge without compromising our objective, a technique is presented that advances contemporary work. We propose an implementation scheme for a SCOOP compiler that effectively synchronizes the external and internal representation of state of objects. As an implication of this scheme, SCOOP would provide the memento design pattern by default. We also show how a portion of an object particular to its state can be replaced dynamically, allowing state dependent polymorphism. Further, we discuss how programs coded in SCOOP can be model checked

Impact of War on Terror in Pakistan, Afghanistan and Beyond

Terrorism, in all its shape and manifestation, is intolerable and condemned, not only in local and international laws, but also in all religions. The world is still continuously infested with the virus of terrorism. In this article, an effort has been made to examine terrorism from different aspects and dimensions including the historical perspective of different terrorist organizations. Prior to 1979, a bipolar world witnessed a cold war for a long period of time, which finally resulted in a war against USSR troops in Afghanistan by the United States and its allies, including Pakistan. The United States and its allies, chiefly Saudi Arabia and Pakistan, orchestrated throngs of the so-called of Mujahideen and Jihadees. Politico-Islam was exploited to its maximum, which recruited these Mujahideen and Jihadees from scores of Muslim countries and launched them into the territory of Afghanistan with the help of Pakistan to fight against the Soviet troops. As a result, the Soviet Union was dismembered, reshaping the globe into a unipolar world led by the United States. Post 9/11 Pakistan had to face the brunt of terrorism by the same very Mujahideen and the people of their mindset, which resulted into devastation of its demography, economy, and human capital, and terrorism became an uncontrollable phenomenon in the entire region and beyond. DOI: 10.7176/IAGS/74-05 Publication date:July 31st 201