Dual Job Search and Migration (2018) - submitted
with: Christine Braun and Peter Rupert - current draft here
Abstract: Between 1964 and 2000 there were substantial changes in the structure of the labor force and geographic mobility. The fraction of households with both spouses in the labor force increased from 36% to 75%. Female wages relative to their male counterparts increased from .49 to .64. The intercounty migration rate of single individuals increased from 5.4% to 9.1%. However, the migration rate of married couples declined from 5.7% to 5.0%. This paper asks how much of the discrepancy in migration patterns can be accounted for by the above mentioned forces. We find that the rise of dual labor force households can account for 53% of the decline in migration, whereas rising relative wages of women can account for 20% of the decline. In addition, we show that the co-location problem has important implications for estimates of lifetime earnings inequality.
Demographic Obstacles to European Growth (2019) - previously titled Demographics and the European Divide
with Thomas Cooley and Espen Henriksen - SSRN draft here
Abstract: Since the early 1990’s there have been persistent slowdowns in the growth rates of the four largest European economies: France, Germany, Italy, and the United Kingdom. This persistence suggests a low-frequency structural change is at work. Ageing populations, both in terms of longer individual life expectancies and declining fertility have caused a shift in the age-cohort distribution. Growth accounting identifies the following five sources of economic growth: total factor productivity, capital accumulation, labor supply on the intensive and extensive margin, and population growth. Changing demographics directly affects all these five margins. The effects of ageing populations affects economic growth indirectly through the pension systems that are in place and the need to fund them. To fund increasing liabilities with a shrinking tax base, tax rates must increase to balance budgets. This will impose distortions to individual factor-supply choices, providing further headwinds for economic growth. We quantify the additional growth effects resulting from these distortions.
Works in progress
The Asymptotic Bias of Local Projections with Long Run Restrictions
Calibration of a Quasi-Adiabatic Magneto-Thermal Calorimeter Used to Characterize Magnetic Nanoparticle Heating (2013)
with: Anilchandra Attaluri, Michele Wabler, and Robert Ivkov
Abstract: To assess and validate temperature measurement and data analysis techniques for a quasi-adiabatic calorimeter used to measure amplitude-dependent loss power of magnetic nanoparticles exposed to an alternating magnetic field (AMF) at radiofrequencies (160 ± 5 kHz). The data collected and methods developed were used to measure the specific loss power (SLP) for two magnetic iron oxide nanoparticles (IONPs) suspensions, developed for magnetic nanoparticle hyperthermia. Calibration was performed by comparing measured against calculated values of specific absorption rate (SAR) of a copper wire subjected to AMF. Rate of temperature rise from induced eddy currents was measured (n = 4) for a copper wire of radius 0.99 mm and length of 3.38 mm in an AMF at amplitudes (H) of 16, 20, 24, and 28 kA/m. The AMF was generated by applying an alternating current using an 80-kW induction power supply to a capacitance network containing a 13.5-cm vertical solenoid that held the calorimeter. Samples were taped to an optical fiber temperature probe and inserted into a standard (polystyrene, 5 ml) test tube which was suspended in the calorimeter. The sample was subjected to the AMF for 30 s or until the temperature of the sample, increased by 30 °C, recorded at 0.3-s intervals. The SAR of the sample was normalized by H2f1/2, averaged, and compared to theoretical values. Iron (Fe) normalized SLPs of two IONPs (JHU-MION and bionized-nanoferrite (BNF) particles (Micromod Partikeltechnologie, GmbH)) in aqueous suspension were measured in the same setup. We report experimental SAR values for the copper of 2.4 ± 0.1, 4.3 ± 0.2, 6.2 ± 0.1, and 8.5 ± 0.1 W/g compared to theoretical values 3.1 ± 0.1, 4.5 ± 0.2, 6.5 ± 0.1, and 9.2 ± 0.2 W/g at AMF amplitudes of 16 ± 0.1, 20 ± 0.2, 24 ± 0.1, and 28 ± 0.1 kA/m, respectively. Normalized experimental data followed a linear trend approximately parallel to theoretical values with an R2-value of 0.99. The measured SLPs of the JHU particles are higher than BNF particles within the tested AMF amplitude range of 15 kA/m to 45 kA/m. We demonstrated that copper can be used to calibrate magneto-thermal calorimetric systems used for SLP measurements of magnetic nanoparticles for a field range of 15–28 kA/m at 160 ± 5 kHz. We also note that the electrical conductivity, diameter of copper sample and accuracy, and response time of thermometry constrain calibration to lower amplitudes, highlighting the need for development of standard reference materials for such applications.