Quantitative modeling of superconducting planar resonators with improved field homogeneity for electron spin resonance

We present three designs for planar superconducting microwave resonators for electron spin resonance (ESR) experiments. We implement finite element simulations to calculate the resonance frequency and quality factors as well as the three-dimensional microwave magnetic field distribution of the resonators. One particular resonator design offers an increased homogeneity of the microwave magnetic field while the other two show a better confinement of the mode volume. We extend our model simulations to calculate the collective coupling rate between a spin ensemble and a microwave resonator in the presence of an inhomogeneous magnetic resonator field. Continuous-wave ESR experiments of phosphorus donors in $^\mathrm{nat}$Si demonstrate the feasibility of our resonators for magnetic resonance experiments. We extract the collective coupling rate and find a good agreement with our simulation results, corroborating our model approach. Finally, we discuss specific application cases for the different resonator designs

A meta-analysis of the investment-uncertainty relationship

In this article we use meta-analysis to investigate the investment-uncertainty relationship. We focus on the direction and statistical significance of empirical estimates. Specifically, we estimate an ordered probit model and transform the estimated coefficients into marginal effects to reflect the changes in the probability of finding a significantly negative estimate, an insignificant estimate, or a significantly positive estimate. Exploratory data analysis shows that there is little empirical evidence for a positive relationship. The regression results suggest that the source of uncertainty, the level of data aggregation, the underlying model specification, and differences between short- and long-run effects are important sources of variation in study outcomes. These findings are, by and large, robust to the introduction of a trend variable to capture publication trends in the literature. The probability of finding a significantly negative relationship is higher in more recently published studies. JEL Classification: D21, D80, E22 1

Parenthood and Productivity of Highly Skilled Labor: Evidence from the Groves of Academe

We examine the effect of pregnancy and parenthood on the research productivity of academic economists. Combining the survey responses of nearly 10,000 economists with their publication records as documented in their RePEc accounts, we do not find that motherhood is associated with low research productivity. Nor do we find a statistically significant unconditional effect of a first child on research productivity. Conditional difference-in-differences estimates, however, suggest that the effect of parenthood on research productivity is negative for unmarried women and positive for untenured men. Moreover, becoming a mother before 30 years of age appears to have a detrimental effect on research productivity