Gravitational Perfect Fluid Collapse in Gauss-Bonnet Gravity

The Einstein Gauss-Bonnet theory of gravity is the low energy limit of heterotic super-symmetric string theory. This paper deals gravitational collapse of perfect fluid in Einstein Gauss-Bonnet gravity by considering the Lemaitre - Tolman - Bondi metric. For this purpose, the closed form of exact solution of equations of motion has been determined by using the conservation of stress-energy tensor and the condition of marginally bound shells. It has been investigated that the presence of Gauss-Bonnet coupling term $\alpha>0$ and pressure of the fluid modifies the structure and time formation of singularity. In this analysis singularity form earlier than horizon, so end state of the collapse is a naked singularity depending on the initial data. But this singularity is weak and timelike that goes against the investigation of general relativity.Comment: 16 pages, 3 Figures; some future research directions mentioned; to appear in European Physical Journal

Models of Anisotropic Self-Gravitating Source in Einstein-Gauss-Bonnet Gravity

In this paper, we have studied gravitational collapse and expansion of non-static anisotropic fluid in $5D$ Einstein Gauss-Bonnet gravity. For this purpose, the field equations have been modeled and evaluated for the given source and geometry. The two metric functions have been expressed in terms of parametric form of third metric function. We have examined the range of parameter $\beta$ (appearing in the form of metric functions) for which $\Theta$ the expansion scalar becomes positive/negative leads to expansion/collapse of the source. The trapped surface condition has been explored by using definition of Misner-Sharp mass and auxiliary solutions. The auxiliary solutions of the field equations involve a single function which generates two types of anisotropic solutions. Each solution can be represented in term of arbitrary function of time, this function has been chosen arbitrarily to fit the different astrophysical time profiles. The existing solutions forecast gravitational expansion and collapse depending on the choice of initial data. In this case, it has been investigated wall to wall collapse of spherical source. The dynamics of the spherical source has been observed graphically with the effects of Gauss-Bonnet coupling term $\alpha$ in the case of collapse and expansion. The energy conditions are satisfied for the specific values of parameters in the both solutions, this implies that the solutions are physically acceptable.Comment: 20 pages,16 Figures, Title Changed, Major revision included,accepted version to appear in Adv.High Energy Physic

Long read review: the enemy within: a tale of Muslim Britain by Sayeeda Warsi

In The Enemy Within: A Tale of Muslim Britain, Sayeeda Warsi offers a book that is part memoir and part political commentary. Drawing on her Yorkshire childhood as the daughter of Pakistani immigrants and her role as the first female Muslim cabinet member, she reflects on the rise of Islamophobia, government responses to terrorism and questions of difference and identity in contemporary Britain in this frank, insightful and perceptive read, writes Tahir Abbas

Contemporary Turkey in conflict: how ethnic, political and religious conflicts will define Turkey’s future

Since 2015, Turkey has experienced a wave of terrorist attacks, political unrest, and a failed coup attempt. Drawing on research in a new book, Tahir Abbas writes on the radical changes that have occurred in Turkey during the 21st century and the conflicts that are now shaping the country’s future

On the quality of Web Services.

Web Services (WSs) are gaining increasing attention as programming components and so is their quality. WSs offer many benefits, like assured interoperability, and reusability. Conversely, they introduce a number of challenges as far as their quality is concerned, seen from the perspectives of two different stakeholders: (1) the developer/provider of WSs and (2) the consumer of WSs. Developers are usually concerned about the correctness of the WS's functionality which can be assessed by functional testing. Consumers of WSs are usually careful about the reliability of WSs they are depending on (in addition to other qualities). They need to know whether the WSs are available (i.e., up and running), accessible (i.e., they actually accept requests) while available and whether they successfully deliver responses for the incoming requests. Availability, Accessibility, and Successability of WSs are directly related to WS reliability. Assessing these three factors via testing is usually only feasible at late stages of the development life-cycle. If they can be predicted early during the development, they can provide valuable information that may positively influence the engineering of WSs with regards to their quality. In this thesis we focus on assessing the quality of WSs via testing and via prediction. Testing of WSs is addressed by an extensive systematic literature review that focuses on a special type of WSs, the semantic WSs. The main objective of the review is to capture the current state of the art of functional testing of semantic WSs and to identify possible approaches for deriving functional test cases from their requirement specifications. The review follows a predefined procedure that involves automatically searching 5 well-known digital libraries. After applying the selection criteria to the search results, a total of 34 studies were identified as relevant. Required information was extracted from the studies, synthesized and summarized. The results of the systematic literature review showed that it is possible to derive test cases from requirement specifications of semantic WSs based on the different testing approaches identified in the primary studies. In more than half of the identified approaches, test cases are derived from transformed specification models. Petri Nets (and its derivatives) is the mostly used transformation. To derive test cases, different techniques are applied to the specification models. Model checking is largely used for this purpose. Prediction of Availability, Accessibility, and Successability is addressed by a correlational study in which we focused on identifying possible relations between the quality attributes Availability, Accessibility, and Successability and other internal quality measures (e.g., cyclomatic complexity) that may allow building statistically significant predictive models for the three attributes. A total of 34 students interacted freely with 20 pre-selected WSs while internal and external quality measures are collected using a data collection framework designed and implemented specially for this purpose. The collected data are then analyzed using different statistical approaches. The correlational study conducted confirmed that it is possible to build statistically significant predictive models for Accessibility and Successability. A very large number of significant models was built using two different approaches, namely the binary logistic regression and the ordinal logistic regression. Many significant predictive models were selected out of the identified models based on special criteria that take into consideration the predictive power and the stability of the models. The selected models are validated using the bootstrap validation technique. The result of validation showed that only two models out of the selected models are well calibrated and expected to maintain their predictive power when applied to a future dataset. These two models are for predicting Accessibility based on the number of weighted methods (WM) and the number of lines of code (LOC) respectively. The approach and the findings presented in this work for building accurate predictive models for the WSs qualities Availability, Accessibility, and Successability may offer researchers and practitioners an opportunity to examine and build similar predictive models for other WSs qualities, thus allowing for early prediction of the targeted qualities and hence early adjustments during the development to satisfy any requirements imposed on the WSs with regards to the predicted qualities. Early prediction of WSs qualities may help leverage trust on the WSs and reduces development costs, hence increases their adoption

How to prevent the collapse of the liberal-left after Brexit and Trump

The UK’s decision to leave the European Union and Donald Trump’s election as President of the United States have been cited by some commentators as proof that the West is turning away from liberal values. Tahir Abbas argues that in the aftermath of Brexit and Trump, supporters of liberalism require a new movement aimed at reaching a unitary consensus that resists division

Ethnicity and politics in contextualising far right and Islamist extremism

This article critically reviews contemporary understandings of the drivers, objectives, and the social and political distinctions of far right and Islamist extremism as reciprocal and correlative threats. While social structure and identity politics are important themes in the social science literature on the radicalisation of far right and Islamist extremist individuals and groups, there remain significant knowledge and policy gaps. Based on a discourse analysis of two related concepts, this article seeks to explain the nature of similarities and differences. As exclusivist and self-reinforcing narratives, the actions and perspectives of one group embolden the other. Policymakers need to understand far right and Islamist extremism as phenomena with shared local driving forces and impacts. This approach would also avoid duplication of effort, as well as misrecognition and insensitivity, in counterterrorism efforts. It also generates valuable political inroads into grounded notions of social cohesion

Repression, terrorism and fear: Erdoğan’s Turkey heads for the brink

Turkey is in trouble. The failed coup last July gave President Erdoğan further excuse to crack down on opposition parties, the media and academia. Tahir Abbas, who left the country ten days before the abortive putsch, looks at how a country regarded as the great hope of the Muslim world came to be governed by an autocrat and plagued by terrorism

A personality cult that plays on popular fears: how Erdoğan won the Turkish referendum

Turkey has narrowly voted to approve a set of reforms that will place more power in the hands of President Tayip Recep Erdoğan, giving him the ability to appoint judges, abolish the office of prime minister and curtail the role of parliament. Tahir Abbas explains how the febrile atmosphere of the past two years – and in particular popular fear of terrorism – has enabled Erdoğan to win the vote

The Study on Bayesian Control Charting Structures for Monitoring of Linear Profiles

摘要 统计过程控制（SPC）在制造业质量提升方面做出了许多重要贡献而被广泛认可。那些拥有先进和科学设备的高竞争力制造企业，成功运用SPC来监控他们的产品。这些过程可以用适当的概率分布模型来拟合，从而到达关注和感兴趣的质量特性，同时建立相应的控制图，以确保它的参数稳定性。这些控制图主要基于统计学上两种主要的排列，即古典排列和贝叶斯排列。在古典排列下可以假设感兴趣的参数是固定的。在现代化时代固定参数的假设显得不太实际，在竞争环境中需要不断的调整以适应在市场竞争中新的需求。统计学家们喜欢采用另一种奢华的、更好的、可替代的参数作为随机变量，这种更好的替代就是贝叶斯统计。而这种非确定性参数在量化先前的...Abstract Statistical Process Control (SPC) procedures are widely acknowledged to have made many significant contributions to quality enhancement in the manufacturing industry. Most advanced and scientifically equipped competitive manufacturing companies successfully implement SPC for monitoring their productions. These procedures can model the quality characteristic(s) of interest with an appropr...学位：经济学博士院系专业：经济学院_统计学学号：1542013015440