Reforming economic institutions in transition economies: what determines the speed of reform?

This paper studies institutional divergence among two types of transition economies: (1) the former socialist economies of Central and Eastern Europe, which have gradually been converging to European levels of institutional quality, and (2) the countries of the Former Soviet Union, which have, on average, made much less progress with institutional reform. We aim to explain these differences in the speed of institutional reform, which we measure as improvements in four Worldwide Governance Indicators: government effectiveness, regulatory quality, rule of law (including property rights), and control of corruption. We find that the most robust factors explaining institutional divergence are cultural/religious roots (Huntington’s definition of "civilization"), the number of years under a socialist regime, and the presence of natural resource rents. Less significant factors are imperial history (whether a country used to be a member of the Russian empire) and the prospect of EU membership (as proxied by the distance to Brussels in order to avoid endogeneity problems). An interesting finding is that, when political institutions are controlled for, the impact of natural resources is no longer significant. This suggests that the influence of natural resource rents on institutional quality operates through their impact on political institutions

Booms, busts and behavioural heterogeneity in stock prices

We estimate a behavioural heterogeneous agents model with boundedly rational traders who know the fundamental stock price, but disagree about the persistence of deviations from the fundamental. Some agents (fundamentalists) believe in mean-reversion of stock prices, while others (chartists) expect a continuation of the trend. Agents gradually switch between the two rules, based upon their relative performance, leading to self-reinforcing regimes of mean-reversion and trend-following. For the fundamental benchmark price we use two well-known models, the Gordon model with a constant risk premium and the Campbell-Cochrane consumption-habit model with a time-varying risk premium. We estimate a two-type switching model using U.S. stock prices until 2016Q4. The estimations show an improvement over representative agent models that is both statistically and economically significant. Our model suggests that behavioural regime switching strongly amplifies booms and busts, in particular, the dot-com bubble and the financial crisis in 2008

As pequenas brocas do cupuacu, Xyleborus sp. e Hypocryphalus sp. (Coleoptera: Scolytidae): danos e indicacoes de manejo em sistemas agroflorestais de Rondonia.

Trabalho desenvolvido em dois sistemas Agroflorestais na zona rural de Porto Velho - Rondonia. Num deles, ocupando area de 0,6ha, foram plantados cupuacu e bandarra(Schilozobium amazonicum), alem de outras duas especies madeireiras, teca (Tectona grandis) e mogno (Swietenia macrophylla). No outro sistema com area de 1,3ha foram plantadaos cupuacu, pupunha e banana. Alem destas, o sistema recebeu as especies madeireiras: teca, mogno, cedro (Cedrela odorata), ipe (Tabebuia), cerejeira (Torresea acreana, freijo (Cordia sp) e copaiba (Copaifera multijuga). Considerou-se o ataque de Xyleborus sp e Hypocrypahlus sp em relacao as condicoes de cultivo implementadas para o cupuacu em Rondonia. Traz indicacoes de manejo de cultivo em sistemas agroflorestais em areas de "derruba & queima", onde a presenca de tocos(madeira morta) e frequente e significativa.bitstream/item/56213/1/Circ.T-270001.pd

Process Control of Stainless Steel Laser Welding using an Optical Spectroscopic Sensor

The in-process monitoring and real-time control of the penetration depth during laser welding is evaluated. An optical collimator collects the optical emission for measurement with a fast spectrometer. The sensor data are used to calculate the electron temperature and subsequently to determine the weld quality of overlap welds in AISI 304 stainless steel sheets performed both with CW Nd:YAG and CO2 lasers. A PI-controller adjusts the laser power aiming at a constant penetration depth and has been tested for Nd:YAG laser welding. Optical inspection of the weld verifies the results obtained with the proposed closed-loop system of spectroscopic sensor and controller

Imaging of the ejection process of nanosecond laser-induced forward transfer of gold

Laser-induced forward transfer is a direct-write process suitable for high precision 3D printing of several materials. However, the driving forces related to the ejection mechanism of the donor ma-terial are still under debate. So far, most of the experimental studies of nanosecond LIFT, are based on post process analysis of either the donor layer and/or the deposits, which were transferred to the receiving substrate. To gain further insights into the ejection dynamics, this article presents results of a series of imaging experiments of the release process of nanosecond LIFT of a 200 nm thick gold donor layer. Images were obtained using a setup which consists of two dual-shutter cameras. Both cameras were combined with a 50× long-distance microscope and used to capture coaxial and side-view images of the ejection process. Bright field illumination of the scene was accomplished by a 6 ns dual-cavity laser source. For laser fluence just above the transfer threshold, the formation of a jet and the subsequent release of a single droplet was observed. The droplet diameter was esti-mated to be about 2 μm. Analysis of the coaxial images indicates the emission of a spectral broad range light which was identified as thermal radiation

Ultra-short-pulsed laser-machined nanogratings of laser-induced periodic surface structures on thin molybdenum layers

Large areas of regular diffraction nanogratings were produced consisting of so-called laser-induced periodic surface structures (LIPSS) on thin molybdenum layers (<400 nm) deposited on a borosilicate glass substrate. The aim was to produce these structures without ablating nor cracking the molybdenum layer. Ultra short laser pulses were applied using a focused Gaussian beam profile. Processing parameters such as laser fluence, pulse overlap, number of overscans, repetition frequency, wavelength and polarization were varied to study the effect on periodicity, height, and especially regularity of the obtained LIPSS. It was found that a careful choice of the correct laser parameters is required to avoid detrimental mechanical stresses, cracking, and delamination during the laser processing of the layer in order to remain in its correct range of ductility as well as to ensure regular LIPSS. A possible photovoltaic application of these nanogratings could be found in texturing of thin film cells to enhance light trapping mechanisms. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE)

Droplet ejection in laser-induced forward transfer: mechanism for droplet fragmentation

Laser-induced forward transfer is a direct-write method suitable for precision printing of various materials. However, occasional defects (i.e. contamination of the receiver due to the impact of multiple small droplets instead of a single droplet) hamper a widespread application of this method. As the ejection mechanism has not been visualized in detail, the cause of these defects is not understood as yet. Therefore, this article presents an experimental study on the ejection process mechanisms of copper-based picosecond laser-induced forward transfer. Images were obtained using bright field illumination by a 6 ns pulsed laser and a 50× long-distance microscope objective. For laser fluences just above the transfer-threshold, the release of a single droplet is frequently (97%) observed. The typical droplet radius in these cases is estimated to be 3 μm. However, images acquired at a later time in time show multiple droplets in the majority (86%) of the observations. The droplet fragments usually follow the main droplet. Two mechanisms to explain these fragments are proposed: i) break-up of “threads” between the donor layer and the ejected droplet; ii) contraction of the ejected droplet. As the phase of the ejected copper is not identified completely, the exact mechanism is not yet known and will be subject of further research