FARC Terrorism in Colombia: A Clustering Analysis

This paper applies clustering analysis to the Colombian armed conflict. Indeed, when applied to a FARC terrorist act database, this statistical procedure finds a natural clustering of the diferent FARC units according to the diferent types of terrorist acts they commit and identities the military hard core of the FARC. The facts revealed in this paper should be useful not only for future military strategies, but also to determine a better priorization and geographical allocation of the scarce military resources.Clustering Analysis,

Black holes and wormholes subject to conformal mappings

Solutions of the field equations of theories of gravity which admit distinct conformal frame representations can look very different in these frames. We show that Brans class IV solutions describe wormholes in the Jordan frame (in a certain parameter range) but correspond to horizonless geometries in the Einstein frame. The reasons for such a change of behaviour under conformal mappings are elucidated in general, using Brans IV solutions as an example.Comment: 7 pages, 2 figure

Agricultural Price Distortion and Stabilization: Stylized facts and Hypothesis Tests

This paper describes agricultural policy choices and tests some predictions of political economy theories. It begins with three broad stylized facts: governments tend to tax agriculture in poorer countries, and subsidize it in richer ones, tax both imports and exports more than nontradables, and tax more and subsidize less where there is more land per capita. We test a variety of political-economy explanations, finding results consistent with hypothesized effects of rural and urban constituents’ rational ignorance about small per-person effects, governance institutions’ control of rent-seeking by political leaders, governments’ revenue motive for taxation, and the role of time consistency in policy-making. We also find that larger groups obtain more favorable policies, suggesting that positive group size effects outweigh any negative influence from more free-ridership, and that demographically driven entry of new farmers is associated with less favorable farm policies, suggesting the arrival of new farmers erodes policy rents and discourages political activity by incumbents. Another new result is that governments achieve very little price stabilization relative to our benchmark estimates of undistorted prices, and governments in the poorest countries actually destabilize domestic prices.Distorted incentives, agricultural and trade policy reforms, national agricultural development, Agricultural price distortions, political economy, Agricultural and Food Policy, International Relations/Trade, F13, F14, Q17, Q18, D72, D78, F11, H23,

Are quantization rules for horizon areas universal?

Doubts have been expressed on the universality of holographic/string-inspired quantization rules for the horizon areas of stationary black holes or the products of their radii, already in simple 4-dimensional general relativity. Realistic black holes are not stationary but time-dependent. Using two examples of 4D general-relativistic spacetimes containing dynamical black holes for at least part of the time, it is shown that the quantization rules (even counting virtual horizons) cannot hold, except possibly at isolated instants of time, and do not seem to be universal.Comment: One example and one figure added, two figures improved, bibliography expanded and updated. Matches the version accepted for publication in Phys. Rev.