Towards electron transport measurements in chemically modified graphene: The effect of a solvent

Chemical functionalization of graphene modifies the local electron density of the carbon atoms and hence electron transport. Measuring these changes allows for a closer understanding of the chemical interaction and the influence of functionalization on the graphene lattice. However, not only chemistry, in this case diazonium chemistry, has an effect on the electron transport. Latter is also influenced by defects and dopants resulting from different processing steps. Here, we show that solvents used in the chemical reaction process change the transport properties. In more detail, the investigated combination of isopropanol and heating treatment reduces the doping concentration and significantly increases the mobility of graphene. Furthermore, the isopropanol treatment alone increases the concentration of dopants and introduces an asymmetry between electron and hole transport which might be difficult to distinguish from the effect of functionalization. The results shown in this work demand a closer look on the influence of solvents used for chemical modification in order to understand their influence

The Structure of AdS Black Holes and Chern Simons Theory in 2+1 Dimensions

We study anti-de Sitter black holes in 2+1 dimensions in terms of Chern Simons gauge theory of anti-de Sitter group coupled to a source. Taking the source to be an anti-de Sitter state specified by its Casimir invariants, we show how all the relevant features of the black hole are accounted for. The requirement that the source be a unitary representation leads to a discrete tower of states which provide a microscopic model for the black hole.Comment: 17 pages, LaTex. The presentation in Section 5 was improved; other minor improvements. Final form of the manuscrip

Ties to the Rest: Autocratic Linkages and Regime Survival

The relationship between international linkages and the nature and survival of political regimes has gained increasing attention in recent years, but remains one that is poorly understood. In this article, we make three central contributions to our understanding of international linkage politics and autocratic regime survival. First, we introduce and develop the concept of “autocratic linkage,” and highlight its importance for understanding the international politics of autocratic survival. Second, we use event history analysis to demonstrate that autocratic linkage has a systematic effect on the duration of authoritarian regimes. Finally, we complement our quantitative analysis with a focused comparison of autocratic linkage politics in the Middle East. We show that variation in Saudi Arabian support for autocratic incumbents in the wake of the Arab Spring protests can be explained in significant part by variation in linkage relationships

Coup Agency and Prospects for Democracy

This research note introduces new global data on military coups. Conventional aggregate data so far have conflated two distinct types of coups. Military interventions by leading officers are coups "from above,"characterized by political power struggles within authoritarian elite coalitions where officers move against civilian elites, executive incumbents, and their loyal security personnel. By contrast, power grabs by officers from the lower and middle ranks are coups "from below,"where military personnel outside of the political elite challenge sitting incumbents, their loyalists, and the regime itself. Disaggregating coup types offers leverage to revise important questions about the causes and consequences of military intervention in politics. This research note illustrates that coup attempts from the top of the military hierarchy are much more likely to be successful than coups from the lower and middle ranks of the military hierarchy. Moreover, coups from the top recalibrate authoritarian elite coalitions and serve to sustain autocratic rule; they rarely produce an opening for a democratic transition. Successful coups from below, by contrast, can result in the breakdown of authoritarian regimes and generate an opening for democratic transitions

The s-process branching at 185W

The neutron capture cross section of the unstable nucleus 185W has been derived from experimental photoactivation data of the inverse reaction 186W(gamma,n)185W. The new result of sigma = (687 +- 110) mbarn confirms the theoretically predicted neutron capture cross section of 185W of sigma = 700 mbarn at kT = 30 keV. A neutron density in the classical s-process of n_n = (3.8 +0.9 -0.8} * 1e8 cm-3 is derived from the new data for the 185W branching. In a stellar s-process model one finds a significant overproduction of the residual s-only nucleus 186Os.Comment: ApJ, in pres

Enraizamento de estacas de Piptocarpha angustifolia Dusén sob efeito de ácido indol butírico no outono e inverno de 2004.

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