The Economic Diversity of Immigration Across the United States

While it is well known that some areas of the United States receive more immigrants than others, less is understood about the extent to which the character of immigration varies as well. There is much broader geographic variation in the skill and demographic composition of immigrants than natives, with important implications for their economic effects. This paper provides a new perspective by focusing on heterogeneity in outcomes such as the share of population growth due to immigration, the presence of immigrant children in schools, and the effect of immigration on the age, sex, language, and educational composition of the local population and workforce.

Are Drone Strikes Effective in Afghanistan and Pakistan? On the Dynamics of Violence between the United States and the Taliban

Strikes by unmanned aerial vehicles, or drones, have been the primary weapon used by the United States to combat the Taliban and Al-Qaeda in Afghanistan and Pakistan. This paper examines the dynamics of violence involving drone strikes and the Taliban/Al-Qaeda in Afghanistan and Pakistan from January 2007 to December 2010. We find that drone strikes do not have any significant impact on terrorist violence in Afghanistan but that drone strikes do have a significant impact on Taliban/Al-Qaeda violence in Pakistan. We find that our results are robust to examining different time periods and lag structures. We also examine the impact of successful and unsuccessful drone strikes (which did or did not succeed in targeted killing of a militant leader) on terrorist attacks by the Taliban. We find strong negative impacts of unsuccessful drone strikes on Taliban violence in Pakistan, showing the deterrent effects are quite strong, while the incapacitation effects appear to be weak or non-existent.time series models, conflict

On the Sensitivity of Return to Schooling Estimates to Estimation Methods, Model Specification, and Influential Outliers If Identification Is Weak

We provide a comparison of return to schooling estimates based on an influential study by Angrist and Krueger (1991) using two stage least squares (TSLS), limited information maximum likelihood (LIML), jackknife (JIVE), and split sample instrumental variables (SSIV) estimation. We find that the estimated return to education is quite sensitive to the age controls used in the models as well as the estimation method used. In particular, we provide evidence that JIVE coefficients' standard errors are inflated by a group of extreme years of education observations, for which identification is especially weak. We propose to use Cook's Distance in order to identify influential outliers having substantial influence on first-stage JIVE coefficients and fitted values.Cook's Distance, heteroskedasticity, outliers, return to education, specification, weak instruments

Coherent State Quantum Key Distribution with Entanglement Witnessing

An entanglement witness approach to quantum coherent state key distribution and a system for its practical implementation are described. In this approach, eavesdropping can be detected by a change in sign of either of two witness functions, an entanglement witness S or an eavesdropping witness W. The effects of loss and eavesdropping on system operation are evaluated as a function of distance. Although the eavesdropping witness W does not directly witness entanglement for the system, its behavior remains related to that of the true entanglement witness S. Furthermore, W is easier to implement experimentally than S. W crosses the axis at a finite distance, in a manner reminiscent of entanglement sudden death. The distance at which this occurs changes measurably when an eavesdropper is present. The distance dependance of the two witnesses due to amplitude reduction and due to increased variance resulting from both ordinary propagation losses and possible eavesdropping activity is provided. Finally, the information content and secure key rate of a continuous variable protocol using this witness approach are given

Essays in Empirical Labor Economics: Dissertation Summary

This dissertation contains three essays which are loosely organized around the role that educational attainment and skill plays in the labor market. The first essay examines the effects of the large changes in the supply of immigrant labor to the U.S. labor market during the 1980s. The second essay estimates sheepskin effects in the returns to education using a data set that contains information on both degrees received and the highest grade that individuals completed. This essay was written jointly with Marianne Page. The third essay proposes a reconciliation scheme for the old and new educational attainment questions in the Current Population Survey and the decennial U.S. Census

Contemplative Experience - Pointing to the same Reality?

The world\u27s religious traditions have a history of writers and mystics who claim to have experienced contact with God or ultimate reality. How do these experiences emerge? Do they all point to the same thing

Fiber-Cavity optomechanics with hexagonal boron nitride drum resonators

In an effort to overcome the limits imposed by the inherently weak radiation pressure interaction, the field of optomechanics aims to miniaturize both the mechanical elements and the mode volume of the optical cavities involved. Like this, the interaction can be boosted, and the quantum regime comes within reach. The possibility of introducing additional elements into the system, such as quantum emitters, offers alternative ways to move past current experimental limitations. This calls for versatile experimental platforms with a small footprint that allow for the integration and exploration of novel materials and experimental protocols. Here we present a fiber based Fabry-Perot cavity that can be operated under atmospheric conditions, under vacuum, and at 4K. We demonstrate our ability to stabilize the cavity length within the cavity linewidth while maintaining full tunability and a high finesse. We fabricate mechanical drum resonators by suspending flakes of hexagonal boron-nitride over holes in a high-stress $Si_{3}N_{4}$ membrane. By imaging their motion and measuring their thermal displacement spectra, we characterize these drums and their hybridization with the underlying $Si_{3}N_{4}$ membrane. The observed mode shapes are consistent with theoretical models and finite-element simulations of an ideal drum, revealing that our fabrication procedure introduce little imperfections. The analysis of the thermal spectra reveals that hybridization with the $Si_{3}N_{4}$ membrane can shift the quality factor and effective mass of the drum modes by several orders of magnitude. This could be an important tool in the endeavor to improve the moderate mechanical quality factors of 2D material oscillators, and further enhance their sensitivity. Combining our cavity with our hBN drum resonator yields an optomechanical platform with a single-photon coupling of up to g_0=230\,\mbox{kHz}, several orders of magnitude higher than previous implementations employing mechanical resonators made of 2D materials. This high value is made possible by the small mode volume of our microscale cavity, as well as the low effective mass of our hBN drum resonator. Finally, the combination of the high stability of our system with this strong interaction allowed us to measure the optomechanically induced transparency effect, highlighting the potential of our experimental platform

The Cure Can Be Worse than the Disease: A Cautionary Tale Regarding Instrumental Variables

In this paper we draw attention to two problems associated with the use of instrumental variables (IV) whose importance for empirical work has not been fully appreciated. First, using potential instruments that explain little of the variation in the: endogenous explanatory variables can lead to large inconsistencies of the IV estimates even If only a weal

The Persistence of Self-Employment Across Borders: New Evidence on Legal Immigrants to the United States

Using recently-available data from the New Immigrant Survey, we find that previous self-employment experience in an immigrant's country of origin is an important determinant of their self-employment status in the U.S., increasing the probability of being self-employed by about 7 percent. Our results improve on the previous literature by measuring home-country self-employment directly rather than relying on proxy measures. We find little evidence to suggest that home-country selfemployment has a significant effect on U.S. wages in either paid employment or self employment.Self-employment, entrepreneurship, New Immigrant Survey