Labor market impacts of states issuing of driver's licenses to undocumented immigrants

Over the last years several states have enacted policies granting undocumented immigrants access to driver's licenses. We exploit the state and temporal variation in the issuing of state driver's licenses to undocumented immigrants to estimate their impact on labor market outcomes. Using 2005 through 2017 data from the American Community Survey, we show that likely undocumented men increase their weekly hours of work in response to the availability of driver's licenses. Perhaps due to their already high labor force participation, the impact is somewhat moderate. We also find no similar impacts among similarly skilled foreign-born Hispanic men who have naturalized. The policy slightly raises commuting time, suggesting changes in work patterns, as well as likely undocumented immigrants’ propensity to have an occupation that requires driving. At a time when anti-immigrant sentiments are at an all-time high, understanding how these policies impact targeted groups and similarly skilled citizens is crucial for maintaining an informed immigration policy debate

Timing is Everything when Fighting a Pandemic: COVID-19 Mortality in Spain

In an effort to contain the spread of the COVID-19 pandemic, many countries around the globe adopted social distancing measures. Previous studies have relied on the geographical and temporal variation in the adoption of non-pharmaceutical interventions (NPIs) to show that early adoption of NPIs is correlated to lower infection and mortality rates. However, due to the non-random adoption of NPIs, the findings may not be interpreted as causal. We address this limitation using a different source of identification –namely, the regional variation in the placement on the pandemic curve at the time of a nationwide lockdown. Our results reveal how, relative to regions for which the lockdown arrived 10+ days after the pandemic's outbreak, regions where the outbreak had just started were able to lower their daily fatality rate by 2.5 deaths per 100,000 inhabitants. We also provide suggestive evidence of contagion deceleration as the main mechanism behind the effectiveness of the early adoption of NPIs in lowering the death rate, rather than increased healthcare capacity

COVID-19 School Closures and Parental Labor Supply in the United States

We examine the role of school closures in contributing to the negative labor market impacts of the COVID-19 pandemic. We collect detailed daily information on school closures at the school-district level, which we merge to individual level data on various employment and socio- demographic characteristics from the monthly Current Population Survey from January 2019 through May 2020. Using a difference-in-differences estimation approach, we gauge how the intensity of school closures affects the labor supply of mothers and fathers of young school-age children. We find evidence of non-negligible labor supply reductions, particularly among mothers. These impacts prove robust to endogeneity checks and persist after accounting for other social-distancing measures in place

Employment Expectations and Gross Flows by Type of Work Contract

There is growing interest in understanding firms’ temporary and permanent employment practices and how institutional changes shape them. Using data on Spanish establishments, we examine: (a) how employers adjust temporary and permanent job and worker flows to prior employment expectations, and (b) how the 1994 and 1997 labour reforms promoting permanent employment affected establishments’ employment practices. Generally, establishments’ prior employment expectations are realized through changes in all job and worker flows. However, establishments uniquely rely on temporary hires as a buffer to confront diminishing long-run employment expectations. None of the reforms significantly affected establishments’ net temporary or permanent employment flows.http://deepblue.lib.umich.edu/bitstream/2027.42/40032/3/wp646.pd

Unprecedented Alexandrium blooms in a previously low biotoxin risk area of Tasmania, Australia.

During October 2012, a shipment of blue mussels (Mytilus galloprovincialis) from the poorly monitored east coast of Tasmania, Australia, was tested by Japanese import authorities and found to be contaminated with unacceptable levels of Paralytic Shellfish Toxins (PSTs; 10 mg/kg). Subsequently local oysters, scallops, clams, the viscera of abalone and rock lobsters were also found to be contaminated. This led to a global product recall and loss to the local economy of AUD 23M. Following low toxicity during 2013 and 2014 and implementation of minimal shellfish farm closures, a more severe bloom event occurred during July-November 2015 and again June-September 2016 (up to 300,000 Alexandrium cells/L; 24 mg/kg PST in mussels, 6 mg/kg in Crassostrea gigas oysters), also causing 4 human illnesses resulting in hospitalization after consumption of wild shellfish. While Alexandrium tamarense had been detected in low concentrations in southeastern Australia since 1987, all cultured strains belonged to the mostly non-toxic group 5 (now designated A. australiense; detected since 1987) and weakly toxic group 4 (A. pacificum; detected in 1997). In contrast, the 2012 to 2016 outbreaks were dominated by highly toxic group 1 (A. fundyense) never detected previously in the Australian region. Molecular analyses suggest that A. fundyense may have been a cryptic ribotype previously present in Tasmania, but newly stimulated by altered water column stratification conditions driven by changing rainfall and temperature patterns. Increased seafood and plankton monitoring of the area now include the implementation of Alexandrium qPCR, routine Neogen™ immunological and HPLC PST tests, but ultimately may also drive change in harvesting strategies and aquaculture species selection by the local seafood industry

Magnetic Anisotropy of a Single Cobalt Nanoparticle

Using a new microSQUID set-up, we investigate magnetic anisotropy in a single 1000-atoms cobalt cluster. This system opens new fields in the characterization and the understanding of the origin of magnetic anisotropy in such nanoparticles. For this purpose, we report three-dimensional switching field measurements performed on a 3 nm cobalt cluster embedded in a niobium matrix. We are able to separate the different magnetic anisotropy contributions and evidence the dominating role of the cluster surface.Comment: 4 pages, 8 figure

Structure and Magnetism of well-defined cobalt nanoparticles embedded in a niobium matrix

Our recent studies on Co-clusters embedded in various matrices reveal that the co-deposition technique (simultaneous deposition of two beams : one for the pre-formed clusters and one for the matrix atoms) is a powerful tool to prepare magnetic nanostructures with any couple of materials even though they are miscible. We study, both sharply related, structure and magnetism of the Co/Nb system. Because such a heterogeneous system needs to be described at different scales, we used microscopic and macroscopic techniques but also local selective absorption ones. We conclude that our clusters are 3 nm diameter f.c.c truncated octahedrons with a pure cobalt core and a solid solution between Co and Nb located at the interface which could be responsible for the magnetically inactive monolayers we found. The use of a very diluted Co/Nb film, further lithographed, would allow us to achieve a pattern of microsquid devices in view to study the magnetic dynamics of a single-Co cluster.Comment: 7 TeX pages, 9 Postscript figures, detailed heading adde

Half-Metallic Graphene Nanoribbons

Electrical current can be completely spin polarized in a class of materials known as half-metals, as a result of the coexistence of metallic nature for electrons with one spin orientation and insulating for electrons with the other. Such asymmetric electronic states for the different spins have been predicted for some ferromagnetic metals - for example, the Heusler compounds- and were first observed in a manganese perovskite. In view of the potential for use of this property in realizing spin-based electronics, substantial efforts have been made to search for half-metallic materials. However, organic materials have hardly been investigated in this context even though carbon-based nanostructures hold significant promise for future electronic device. Here we predict half-metallicity in nanometre-scale graphene ribbons by using first-principles calculations. We show that this phenomenon is realizable if in-plane homogeneous electric fields are applied across the zigzag-shaped edges of the graphene nanoribbons, and that their magnetic property can be controlled by the external electric fields. The results are not only of scientific interests in the interplay between electric fields and electronic spin degree of freedom in solids but may also open a new path to explore spintronics at nanometre scale, based on graphene

Structural Properties of Ego Networks

The structure of real-world social networks in large part determines the evolution of social phenomena, including opinion formation, diffusion of information and influence, and the spread of disease. Globally, network structure is characterized by features such as degree distribution, degree assortativity, and clustering coefficient. However, information about global structure is usually not available to each vertex. Instead, each vertex's knowledge is generally limited to the locally observable portion of the network consisting of the subgraph over its immediate neighbors. Such subgraphs, known as ego networks, have properties that can differ substantially from those of the global network. In this paper, we study the structural properties of ego networks and show how they relate to the global properties of networks from which they are derived. Through empirical comparisons and mathematical derivations, we show that structural features, similar to static attributes, suffer from paradoxes. We quantify the differences between global information about network structure and local estimates. This knowledge allows us to better identify and correct the biases arising from incomplete local information.Comment: Accepted by SBP 2015, to appear in the proceeding

Magnetocrystalline Anisotropy Energy of Transition Metal Thin Films: A Non-perturbative Theory

The magnetocrystalline anisotropy energy E(anis) of free-standing monolayers and thin films of Fe and Ni is determined using two different semi-empirical schemes. Within a tight-binding calculation for the 3d bands alone, we analyze in detail the relation between bandstructure and E(anis), treating spin-orbit coupling non-pertubatively. We find important contributions to E(anis) due to the lifting of band degeneracies near the Fermi level by SOC. The important role of degeneracies is supported by the calculation of the electron temperature dependence of the magnetocrystalline anisotropy energy, which decreases with the temperature increasing on a scale of several hundred K. In general, E(anis) scales with the square of the SOC constant. Including 4s bands and s-d hybridization, the combined interpolation scheme yields anisotropy energies that quantitatively agree well with experiments for Fe and Ni monolayers on Cu(001). Finally, the anisotropy energy is calculated for systems of up to 14 layers. Even after including s-bands and for multilayers, the importance of degeneracies persists. Considering a fixed fct-Fe structure, we find a reorientation of the magnetization from perpendicular to in-plane at about 4 layers. For Ni, we find the correct in-plane easy-axis for the monolayer. However, since the anisotropy energy remains nearly constant, we do not find the experimentally observed reorientation.Comment: 15 pages, Revtex, 15 postscript figure