1,484 research outputs found

    Mass and angular momentum of black holes in 3D gravity theories with first order formalism

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    We apply the Wald formalism to obtain masses and angular momenta of black holes in three dimensional gravity theories using the first order formalism. Wald formalism suggests that the entropy of a black hole can be defined by an integration of a conserved charge on the bifurcation horizon, and mass and angular momentum of a black hole as an integration of some charge variation form at spatial infinity. The action of three dimensional gravity theories can be represented by a form including some auxiliary fields. As well-known examples we have calculated masses and angular momenta of some black holes in topologically massive gravity and new massive gravity theories using the first order formalism. We have also calculated mass and angular momentum of BTZ black hole and new type black hole in minimal massive gravity theory with the action represented by the first order formalism. We have also calculated the entropy and central charges of new type black hole. According to AdS/CFTAdS/CFT correspondence we suggest that the left and right moving temperatures should be equal to the Hawking temperature in the case of new type black hole in minimal massive gravity.Comment: 35 pages, title changed back to original one, some contents are added and correcte

    Developmental Perspectives on the Root Causes of the Middle Eastā€™s Challenges: The Question of Institutional and Social Adaptability

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    The Middle East and North Africa is considered a region highly prone to instability and conflict, and where religiosity and sectarianism assumes prominence. It is commonly thought that the source of the MENA countriesā€™ troubles is primarily political in nature and hence they require mainly political responses. The regionā€™s historical legacies and geopolitics entailing foreign interventions would only reinforce such perception but ā€˜hard politicsā€™ clearly has limitations in resolving such challenges. Instead, ā€˜developmentā€™ assumes much more pertinence than meets the eye; the multidisciplinary developmental approach opens a whole new window of opportunity for understanding the nature and root causes of the MENAā€™s challenges and its way forward, by unraveling the complexities of the region. At the heart of the matter is the question of adapting to the changes of the times, of making the necessary institutional, social-behavioral changes to deal with the reality. The countriesā€™ major challenges are inherently due to their lack of development in the key areas: ā€˜within-state developmentā€™, ā€˜participatory developmentā€™, state capacity, and secularization.

    Re-Inventing Africa's Development

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    This open access book analyses the development problems of sub-Sahara Africa (SSA) from the eyes of a Korean diplomat with knowledge of the economic growth Korea has experienced in recent decades. The author argues that Africa's development challenges are not due to a lack of resources but a lack of management, presenting an alternative to the traditional view that Africa's problems are caused by a lack of leadership. In exploring an approach based on mind-set and nation-building, rather than unity ā€“ which tends to promote individual or party interests rather than the broader country or national interests ā€“ the author suggests new solutions for SSA's economic growth, inspired by Korea's successful economic growth model much of which is focused on industrialisation. This book will be of interest to researchers, policymakers, NGOs and governmental bodies in economics, development and politics studying Africa's economic development, and Korea's economic growth model

    Mass and Angular momentum of Black Holes in New Massive Gravity

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    We obtain mass and angular momentum of black holes as conserved charges in three dimensional new massive gravity, after presenting the explicit expression for the potential of the conserved charges. This confirms the expression of those charges obtained in several ways, in particular through AdS/CFT correspondence, and shows us that the first law of black hole thermodynamics is valid in these black holes. We also comment about conserved charges in new type black holes with the emphasis on the AdS/CFT correspondence as guiding principle.Comment: minor corrections, added conclusion, accepted in PR

    A Study on Brightness Improvement and Deterioration of ZnS:Cu Electroluminescence

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