http://hdl.handle.net/1721.1/7780 Thu, 23 May 2013 06:19:44 GMT 2013-05-23T06:19:44Z http://hdl.handle.net/1721.1/68968 The Toppler Effect : irregular leader transitions and the rate of state failure recovery Wahedi, Laila A State failure is becoming increasingly prevalent across the globe, creating human suffering, black markets, lost economic opportunities, and safe havens for militant actors. It is imperative that the international community find a way to combat state failure. This study investigates the effects of irregular leadership transitions on state failure recovery. Irregular leadership transitions occur when the executive of a state comes to power through unconstitutional means. Regular leaders are more likely than irregular leaders to have personal experience as a ruler, beneficial domestic and international ties, and familiarity among the population. Irregular transitions may damage bureaucracies, damaging government functionality and halting development projects that had already been underway. Regular leaders benefit from a legacy that was likely able to pass spoils onto an elite group. This elite group is likely to resist relative losses to power more than lower status groups would fight to gain power because of the cognitive principles of risk aversion, and the sensitivity to status inherent to social identity theory. Regular leaders also have traditional legitimacy, while irregular leaders are more likely to have to gain legitimacy. State failure and failure recovery are overdetermined, so it is impossible to be able to confidently determine the direction of causal flow. Every determinant of failure is related to every other, and it is difficult to separate their effects. The role of leadership regularity is therefore investigated as a proxy that can predict variation on the rate of failure recovery. The quantitative analysis consisted of multi and bivariate regressions investigating the effects of leadership regularity on failure duration, as well as the relative explanatory power held by several factors associated with leadership regularity. Robustness checks were performed using Bayesian statistics, and survival analyses. Irregular leadership transitions were found to predict a roughly five year increase in state failure duration. The Afghan Civil War was used as an illustrative case, describing the ways in which Daoud, Taraki, Amin, Karmal, Massoud, Hekmatyar, and Mullah Omar all overcame, or failed to overcome, different obstacles associated with their irregularity and how these obstacles affected their relative levels of success attempting to extend governance. Thesis (S.M. and S.B.)--Massachusetts Institute of Technology, Dept. of Political Science; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2011.; Cataloged from PDF version of thesis.; Includes bibliographical references (p. 81-86). Sat, 01 Jan 2011 00:00:00 GMT http://hdl.handle.net/1721.1/68968 2011-01-01T00:00:00Z http://hdl.handle.net/1721.1/32741 Ca2+ dependant synaptic modification Huh, Dongsung, 1981- It has been assumed that Ca2+ influx of different duration and amplitude would generate different level of potentiation. The conventional protocols of generating LTP have been 1. tetanic stimulation of presynaptic cell, 2. theta burst stimulation of presynaptic cell, and 3. correlated stimulation of pre- and post-synaptic cells. However, the effects of different Ca2+ influx can not be precisely dissected with the conventional protocols for the following defects: 1. the protocols do not discriminate between pre- and post-synaptic side plasticity, 2. the protocols observe synaptic plasticity between two cells which involve multiple synapses with heterogeneous properties, 3. precise control and measurement of the amount of Ca2+ influx are not possible in the protocols. In the present experiment, we perfused glutamate directly on to a single postsynaptic site, depolarized the postsynaptic intracellular potential to a controlled voltage for a controlled duration of time, thus controlling the opening of postsynaptic NMDA receptors and Ca2+ influx. By using this method, we found 1. that modification of synaptic strength has a bell-shaped dependency to the amount of Ca2+ influx, 2. that weak Ca2+ current through desensitized NMDA receptors sustained for a long period of time (160 ms) generates LTD, 3. evidence that phosphorylation of AMPAR leads to insertion of AMPAR. Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2004.; Includes bibliographical references (p. 21-22). Thu, 01 Jan 2004 00:00:00 GMT http://hdl.handle.net/1721.1/32741 2004-01-01T00:00:00Z