The Size Distribution of Farms and International Productivity Differences

There is a 34-fold difference in average farm size (land per farm) between rich and poor countries and striking differences in their size distributions. Since labor productivity is much higher in large relative to small farms, we study the determinants of farm-size differences across countries and their impact on agricultural and aggregate productivity. We develop a quantitative model of agriculture and non-agriculture that features a non-degenerate size distribution of farms. We find that measured aggregate factors such as capital, land, and economy-wide productivity cannot account for more than 1/4 of the observed differences in farm size and productivity. We argue that, among the possible explanations, farm-level policies that misallocate resources from large to small farms have the most potential to account for the remaining differences. Such farm-size distortions are prevalent in poor countries. We quantify the effects of two specific policies in developing countries: (a) a land reform that imposes a ceiling on farm size and (b) a progressive land tax. We find that each individual policy generates a reduction of 3 to 7% in average size and productivity.aggregate productivity, agriculture, farm-size distortions, misallocation

Relative Stagnation alla Turca

Turkey is the only founding member of the OECD that has not converged to the US in terms of per-capita GDP since 1950: its real GDP per capita is stuck at 20% of that of the US. At a proximate level, we show that Turkey's relative stagnation over the past 50 years is due to: (1) the relative decline in its labor force participation, and (2) the relative stagnation of its TFP. We argue that the first fact is due to policies of high personal income taxation, and high social security contributions for both employees and employers. The second fact we argue is due to price support policies in agriculture, which distorted the allocation of resources in favor of agriculture, thereby delayed the process of the structural transformation. We develop a dynamic general equilibrium model with agricultural and non-agricultural sectors. The production of the non-agricultural good can take place in the market or the household sector. We show the extent to which these policies can account quantitatively for Turkey's relative stagnationRelative Stagnation, Labor Force Participation, Income Taxes

Frustration-induced nanometre-scale inhomogeneity in a triangular antiferromagnet

Phase inhomogeneity of otherwise chemically homogenous electronic systems is an essential ingredient leading to fascinating functional properties, such as high-$T_c$ superconductivity in cuprates, colossal magnetoresistance in manganites, and giant electrostriction in relaxors. In these materials distinct phases compete and can coexist due to intertwined ordered parameters. Charge degrees of freedom play a fundamental role, although phase-separated ground states have been envisioned theoretically also for pure spin systems with geometrical frustration that serves as a source of phase competition. Here we report a paradigmatic magnetostructurally inhomogenous ground state of the geometrically frustrated $\alpha$-NaMnO$_2$ that stems from the system's aspiration to remove magnetic degeneracy and is possible only due to the existence of near-degenerate crystal structures. Synchrotron X-ray diffraction, nuclear magnetic resonance and muon spin relaxation show that the spin configuration of a monoclinic phase is disrupted by magnetically short-range ordered nanoscale triclinic regions, thus revealing a novel complex state of matter.Comment: version equivalent to the one published in Nature Communications, freely available at http://www.nature.com/ncomms/2014/140129/ncomms4222/full/ncomms4222.htm

Διερεύνηση πλοήγησης και προγραμματισμού πτήσης με μη επανδρωμένο σύστημα αεροφωτογράφισης

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Προστασία Μνημείων” Β΄ Κατεύθυνση: Υλικά και Επεμβάσεις Συντήρηση