Quasi-Experimental Impact Estimates of Immigrant Labor Supply Shocks: The Role of Treatment and Comparison Group Matching and Relative Skill Composition

This paper examines the employment effects of an increase in labor supply using the politically-driven exodus of ethnic Turks from Bulgaria into Turkey in 1989. The strong involvement of the Turkish state in the settlement of earlier waves of repatriates provides us a strong source of exogenous variation in the 1989 immigrant shock across locations. Using a potential sample of 613 cities and towns in Turkey with variable treatment intensity - in some locations the change in the labor force is almost 10 percent - this analysis places much attention on constructing a matched sample that is well balanced in terms of covariate distributions of the treatment and comparison groups, including matching based on an estimated propensity score. We find a positive effect of repatriates on the unemployment of non-repatriates. In fact, in certain regions, a 10-percentage-point increase in the share of repatriates in the labor force increases the unemployment rate of natives by 4 percentage points. When the analysis is done according to skill groups, we find that the impact is the strongest on the young and on non-repatriates with similar educational attainment.Labor Force and Employment, Immigrant Workers, Quasi experiments

Low Wage Returns to Schooling in a Developing Country: Evidence from a Major Policy Reform in Turkey

In this paper, we estimate the returns on schooling for young men and women in Turkey using the exogenous and substantial variation in schooling across birth-cohorts brought about by the 1997 reform of compulsory schooling. We estimate that among 18- to 26-year-olds, the return from an extra year of schooling is almost zero for men and 3.8 percent for women. The low level of these estimates contrasts starkly with those estimated for other developing countries. We identify several reasons why the returns on schooling are low and why they are higher for women in our context. In particular, the policy alters the schooling distributions of men and women differently, thus the average causal effect we estimate puts a higher weight on the causal effect of schooling at higher grade levels for women than for men

Enhanced thermoelectric properties of the Zintl phase BaGa_2Sb_2 via doping with Na or K

Na- or K-doped samples of Ba_(1−x)(Na, K)xGa_2Sb_2 were prepared by ball-milling followed by hot-pressing. The topological analysis of the electron density of BaGa_2Sb_2 implies a polar covalent nature of the Sb–Ga bonds in which the Sb atoms receive the electrons transferred from Ba rather than the Ga atoms. Successful doping of BaGa_2Sb_2 with Na or K was confirmed with combined microprobe and X-ray diffraction analysis. Alkali metal doping of BaGa_2Sb_2 increased the p-type charge carrier concentration to almost the predicted optimum values (∼10^(20) h^+ cm^(−3)) needed to achieve high thermoelectric performance. With increasing alkali metal concentration, electronic transport was shifted from non-degenerate semiconducting behaviour observed for BaGa_2Sb_2 to degenerate one for Na- or K-doped compounds. Overall, the thermoelectric figure of merit, zT, values reached up to ∼0.65 at 750 K, considerably higher than the undoped sample (zT ∼ 0.1 at 600 K), and a slight improvement relative to previously reported Zn-doped samples (∼0.6 at 800 K)

Syntax for free: representing syntax with binding using parametricity

We show that, in a parametric model of polymorphism, the type ∀ α. ((α → α) → α) → (α → α → α) → α is isomorphic to closed de Bruijn terms. That is, the type of closed higher-order abstract syntax terms is isomorphic to a concrete representation. To demonstrate the proof we have constructed a model of parametric polymorphism inside the Coq proof assistant. The proof of the theorem requires parametricity over Kripke relations. We also investigate some variants of this representation

First-principles calculations and experimental studies of: XYZ 2 thermoelectric compounds: Detailed analysis of van der Waals interactions

First-principles calculations can accelerate the search for novel high-performance thermoelectric materials. However, the prediction of the thermoelectric properties is strongly dependent on the approximations used for the calculations. Here, thermoelectric properties were calculated with different computational approximations (i.e., PBE-GGA, HSE06, spin-orbit coupling and DFT-D3) for three layered XYZ2 compounds (TmAgTe2, YAgTe2, and YCuTe2). In addition to the computations, the structural, electrical and thermal properties of these compounds were measured experimentally and compared to the computations. An enhanced prediction of the crystal structure and heat capacity was achieved with the inclusion of van der Waals interactions due to more accurate modeling of the interatomic forces. In particular, a large shift of the acoustic phonons and low-frequency optical phonons to lower frequencies was observed from the dispersion-optimized structure. From the phonon dispersion curves of these compounds, the ultralow thermal conductivity in the investigated XYZ2 compounds could be described by a recent developed minimum thermal conductivity model. For the prediction of the electrical conductivity, a temperature-dependent relaxation time was used, and it was limited by acoustic phonons. While HSE06 has only a small influence on the electrical properties due to a computed band gap energy of >0.25 eV, the inclusion of both van der Waals interactions and spin-orbit coupling leads to a more accurate band structure, resulting in better prediction of electrical properties. Furthermore, the experimental thermoelectric properties of YAgTe2, TmAg0.95Zn0.05Te2 and TmAg0.95Mg0.05Te2 were measured, showing an increase in zT of TmAg0.95Zn0.05Te2 by more than 35% (zT = 0.47 ± 0.12) compared to TmAgTe2

Quasi-experimental impact estimates of immigrant labor supply shocks: the role of treatment and comparison group matching and relative skill composition

This paper examines the employment effects of an increase in labor supply using the politically-driven exodus of ethnic Turks from Bulgaria into Turkey in 1989. The strong involvement of the Turkish state in the settlement of earlier waves of repatriates provides us a strong source of exogenous variation in the 1989 immigrant shock across locations. Using a potential sample of 613 cities and towns in Turkey with variable treatment intensity—in some locations the change in the labor force is almost 10 percent—this analysis places much attention on constructing a matched sample that is well balanced in terms of covariate distributions of the treatment and comparison groups, including matching based on an estimated propensity score. We find a positive effect of repatriates on the unemployment of non-repatriates. In fact, in certain regions, a 10-percentage-point increase in the share of repatriates in the labor force increases the unemployment rate of natives by 4 percentage points. When the analysis is done according to skill groups, we find that the impact is the strongest on the young and on non-repatriates with similar educational attainment

Quasi-experimental impact estimates of immigrant labor supply shocks: the role of treatment and comparison group matching and relative skill composition

This paper examines the employment effects of an increase in labor supply using the politically-driven exodus of ethnic Turks from Bulgaria into Turkey in 1989. The strong involvement of the Turkish state in the settlement of earlier waves of repatriates provides us a strong source of exogenous variation in the 1989 immigrant shock across locations. Using a potential sample of 613 cities and towns in Turkey with variable treatment intensity—in some locations the change in the labor force is almost 10 percent—this analysis places much attention on constructing a matched sample that is well balanced in terms of covariate distributions of the treatment and comparison groups, including matching based on an estimated propensity score. We find a positive effect of repatriates on the unemployment of non-repatriates. In fact, in certain regions, a 10-percentage-point increase in the share of repatriates in the labor force increases the unemployment rate of natives by 4 percentage points. When the analysis is done according to skill groups, we find that the impact is the strongest on the young and on non-repatriates with similar educational attainment

Thermoelectric Enhancement in BaGa_2Sb_2 by Zn Doping

The Zintl phase BaGa_2Sb_2 has a unique crystal structure in which large tunnels formed by ethane-like dimeric [Sb_3Ga−GaSb_3] units are filled with Ba atoms. BaGa_2Sb_2 was obtained in high purity from ball-milling followed by hot pressing. It shows semiconducting behavior, in agreement with the valence precise Zintl counting and band structure calculations, with a band gap ∼0.4 eV. The thermal conductivity of BaGa_2Sb_2 is found to be relatively low (0.95 W/K m at 550 K), which is an inherent property of compounds with complex crystal structures. As BaGa_2Sb_2 has a low carrier concentration (∼2 × 10^18 h^+/cm^3) at room temperature, the charge carrier tuning was performed by substituting trivalent Ga with divalent Zn. Zn-doped samples display heavily doped p-type semiconducting behavior with carrier concentrations in the range (5−8) × 10^19 h^+/cm^3. Correspondingly, the zT values were increased by a factor of 6 by doping compared to the undoped sample, reaching a value of ∼0.6 at 800 K. Zn-doped BaGa_2Sb_2 can thus be considered as a promising new thermoelectric material for intermediate-temperature applications

Critical Behavior of a Three-State Potts Model on a Voronoi Lattice

We use the single-histogram technique to study the critical behavior of the three-state Potts model on a (random) Voronoi-Delaunay lattice with size ranging from 250 to 8000 sites. We consider the effect of an exponential decay of the interactions with the distance,$J(r)=J_0\exp(-ar)$, with $a>0$, and observe that this system seems to have critical exponents $\gamma$ and $\nu$ which are different from the respective exponents of the three-state Potts model on a regular square lattice. However, the ratio $\gamma/\nu$ remains essentially the same. We find numerical evidences (although not conclusive, due to the small range of system size) that the specific heat on this random system behaves as a power-law for $a=0$ and as a logarithmic divergence for $a=0.5$ and $a=1.0$Comment: 3 pages, 5 figure