Regularity theory for nonautonomous Maxwell equations with perfectly conducting boundary conditions

In this work we study linear Maxwell equations with time- and space-dependent matrix-valued permittivity and permeability on domains with a perfectly conducting boundary. This leads to an initial boundary value problem for a first order hyperbolic system with characteristic boundary. We prove a priori estimates for solutions in $H^m$. Moreover, we show the existence of a unique $H^m$-solution if the coefficients and the data are accordingly regular and satisfy certain compatibility conditions. Since the boundary is characteristic for the Maxwell system, we have to exploit the divergence conditions in the Maxwell equations in order to derive the energy-type $H^m$-estimates. The combination of these estimates with several regularization techniques then yields the existence of solutions in $H^m$.Comment: 44 pages; typo correcte

Cross Section Measurements with Monoenergetic Muon Neutrinos

The monoenergetic 236 MeV muon neutrino from charged kaon decay-at-rest ($K^+ \rightarrow \mu^+ \nu_\mu$) can be used to produce a novel set of cross section measurements. Applicable for short- and long-baseline accelerator-based neutrino oscillation experiments, among others, such measurements would provide a "standard candle" for the energy reconstruction and interaction kinematics relevant for charged current neutrino events near this energy. This neutrino can also be exercised as a unique known-energy, purely weak interacting probe of the nucleus. A number of experiments are set to come online in the next few years that will be able to collect and characterize thousands of these events.Comment: 8 pages, 4 figures; accepted for publication in Phys. Rev. D.; typos fixed and references update

Using Methods of Treatment Evaluation to Estimate the Wage Effect of IT Usage

In this study, I analyze the relationship between IT use and wages in West Germany in 1998/99. I use two estimation approaches: regression based matching and matching on the propensity score. The richness of the data set favors the use of these approaches. The variable of main interest is the average treatment effect for the treated. I find that, given the extensive changes in workplaces that have occurred in recent decades, IT users would be worse off in terms of wages had they not started to use IT. --Computer wage differential,matching

IT Capital, Job Content and Educational Attainment

Based on a large data set containing information on occupations between 1979 and 1999, this study explores the ?black box? surrounding the skill?biased technological change hypothesis by analyzing the mechanisms that induce information technologies to be complementary to employees with higher skill levels. Using direct, multidimensional measures of occupational skill requirements, the analysis shows that IT capital substitutes repetitive manual and repetitive cognitive skills, whereas it complements analytical and interactive skills. These changes in the within occupational task mix result in an increased deployment of employees with high levels of education who have comparative advantages in performing non?repetitive cognitive tasks. --skill-biased technological change,job task content,vocational education

The Effects of Changes in the Unemployment Compensation System on the Adoption of IT by Older Workers

Two main hypotheses can be found in literature on why elderly workers have a lower probability of using information technology than their younger peers: lower learning capabilities and reduced incentives to invest in human capital. I use law changes in the unemployment compensation system enacted in Germany during the 1980s and 1990s to demonstrate that ?incentives? are more important than ?capabilities? in determining variation in IT usage. Elderly workers only fell behind the IT usage rates of their younger peers during the 1980s and 1990s, when unemployment benefits got increasingly generous, thereby reducing their incentives to invest in human capital. --differences-in-differences,computer adoption by older workers,changes in unemployment compensation system

Local wellposedness of quasilinear Maxwell equations with absorbing boundary conditions

In this article we provide a local wellposedness theory for quasilinear Maxwell equations with absorbing boundary conditions in $\mathcal{H}^m$ for $m \geq 3$. The Maxwell equations are equipped with instantaneous nonlinear material laws leading to a quasilinear symmetric hyperbolic first order system. We consider both linear and nonlinear absorbing boundary conditions. We show existence and uniqueness of a local solution, provide a blow-up criterion in the Lipschitz norm, and prove the continuous dependence on the data. In the case of nonlinear boundary conditions we need a smallness assumption on the tangential trace of the solution. The proof is based on detailed apriori estimates and the regularity theory for the corresponding linear problem which we also develop here.Comment: 43 page

Local wellposedness of quasilinear Maxwell equations with conservative interface conditions

We establish a comprehensive local wellposedness theory for the quasilinear Maxwell system with interfaces in the space of piecewise $H^m$-functions for $m \geq 3$. The system is equipped with instantaneous and piecewise regular material laws and perfectly conducting interfaces and boundaries. We also provide a blow-up criterion in the Lipschitz norm and prove the continuous dependence on the data. The proof relies on precise a priori estimates and the regularity theory for the corresponding linear problem also shown here.Comment: 47 page

How does entry regulation influence entry into selfemployment and occupational mobility?

We analyze how an entry regulation that imposes a mandatory educational standard affects entry into self-employment and occupational mobility. We exploit the German reunification as a natural experiment and identify regulatory effects by comparing differences between regulated occupations and unregulated occupations in East Germany with the corresponding differences in West Germany after reunification. Consistent with our expectations, we find that entry regulation reduces entry into selfemployment and occupational mobility after reunification more in regulated occupations in East Germany than in West Germany. Our findings are relevant for transition or emerging economies as well as for mature market economies requiring large structural changes after unforeseen economic shocks