Browsing by Subject "Transitions"

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Open Access
The reform-security dilemma in democratic transitions: the Turkish experience as model?
(Routledge, 2013) Aydinli, E.
In considering the future of budding Middle Eastern democracies, past experience and scholarship show that a possible outcome for even the most "successful" ones is some form of imperfect democracy. Based within the literature on democratic transitions and hybrid regimes, this article explores possible factors leading to such outcomes. It focuses in particular on reform/security dilemmas, and the resulting evolution of dual state structures, in which an unelected and often authoritarian state establishment coexists with democratic institutions and practices, for example, in countries like Russia, Iran, or Pakistan. Much of the literature views such duality as an impasse, and thus considers these countries as trapped within this "hybridness" - discouraging news both for currently defined "hybrid regimes" and for countries like Egypt and Tunisia, which are now launching democratization processes. To better understand the nature and evolution of such regimes, this article looks at the case of Turkey, first tracing the rise and consolidation of the Turkish inner state, generally equated with the Turkish armed forces. It then looks at the apparent diminishing and integration of the inner state through pacts and coalitions among both civilian and military elements, and calls into question whether the pessimistic view of permanent illiberalness is inevitable. © 2013 © 2013 Taylor & Francis.
Open Access
Self-consistent computation of electronic and optical properties of a single exciton in a spherical quantum dot via matrix diagonalization method
(American Institute of Physics, 2009-08-21) Sahin, M.; Nizamoglu, S.; Kavruk, A. E.; Demir, Hilmi Volkan
In this study, we develop and demonstrate an efficient self-consistent calculation schema that computes the electronic structure and optical properties of a single exciton in a spherical quantum dot (QD) with an interacting pair of electron and hole wave functions. To observe modifications on bands, wave functions, and energies due to the attractive Coulomb potential, the full numeric matrix diagonalization technique is employed to determine sublevel energy eigenvalues and their wave functions in effective mass approximation. This treatment allows to observe that the conduction and valance band edges bend, that the electron and hole wave functions strongly localize in the QD, and that the excitonic energy level exhibits redshift. In our approach for the Coulomb term between electron and hole, the Poisson-Schrodinger equations are solved self-consistently in the Hartree approximation. Subsequently, exciton binding energies and associated optical properties are computed. The results are presented as a function of QD radii and photon energies. We conclude that all of these numerical results are in agreement with the experimental studies.