Celebrating 150 Years of Analyzing Fertility Trends in Germany

Ever since the very beginning of the Journal of Economics and Statistics, population economics has featured prominently in the Journal. Fertility naturally plays an important role in population economics. Its size has decreased significantly from the 1900s. Long time-series regarding fertility and basic trends in Germany are documented and analyzed. We identify three different explanatory approaches for the decline in fertility, according to which the various articles of the Journal related to this area are categorized. The paper also investigates previous fertility studies published by the Journal since the beginning. It points out that several articles anticipated subsequent research directions in the area of population economics at an early stage. In addition, significant contributions were made in terms of further developing existing knowledge. Thus, the Journal has helped to expand the research area of population economics.self-regulation, Malthus, total fertility rate, fertility, Q-Q trade-off

On the recombination in high-order harmonic generation in molecules

We show that the dependence of high-order harmonic generation (HHG) on the molecular orientation can be understood within a theoretical treatment that does not involve the strong field of the laser. The results for H_2 show excellent agreement with time-dependent strong field calculations for model molecules, and this motivates a prediction for the orientation dependence of HHG from the N_2 3s_g valence orbital. For both molecules, we find that the polarization of recombination photons is influenced by the molecular orientation. The variations are particularly pronounced for the N_2 valence orbital, which can be explained by the presence of atomic p-orbitals.Comment: 6 pages 7 figure

Stripe-hexagon competition in forced pattern forming systems with broken up-down symmetry

We investigate the response of two-dimensional pattern forming systems with a broken up-down symmetry, such as chemical reactions, to spatially resonant forcing and propose related experiments. The nonlinear behavior immediately above threshold is analyzed in terms of amplitude equations suggested for a $1:2$ and $1:1$ ratio between the wavelength of the spatial periodic forcing and the wavelength of the pattern of the respective system. Both sets of coupled amplitude equations are derived by a perturbative method from the Lengyel-Epstein model describing a chemical reaction showing Turing patterns, which gives us the opportunity to relate the generic response scenarios to a specific pattern forming system. The nonlinear competition between stripe patterns and distorted hexagons is explored and their range of existence, stability and coexistence is determined. Whereas without modulations hexagonal patterns are always preferred near onset of pattern formation, single mode solutions (stripes) are favored close to threshold for modulation amplitudes beyond some critical value. Hence distorted hexagons only occur in a finite range of the control parameter and their interval of existence shrinks to zero with increasing values of the modulation amplitude. Furthermore depending on the modulation amplitude the transition between stripes and distorted hexagons is either sub- or supercritical.Comment: 10 pages, 12 figures, submitted to Physical Review

Vibrational States of Glassy and Crystalline Orthotherphenyl

Low-frequency vibrations of glassy and crystalline orthoterphenyl are studied by means of neutron scattering. Phonon dispersions are measured along the main axes of a single crystal, and the corresponding longitudinal and transversal sound velocities are obtained. For glassy and polycrystalline samples, a density of vibrational states is determined and cross-checked against other dynamic observables. In the crystal, low-lying zone-boundary modes lead to an excess over the Debye density of states. In the glass, the boson peak is located at even lower frequencies. With increasing temperature, both glass and crystal show anharmonicity.Comment: 7 pages of LaTeX (svjour), 2 tables, 10 figures accepted in Eur. Phys. J.

Carrier-wave Rabi flopping signatures in high-order harmonic generation for alkali atoms

We present the first theoretical investigation of carrier-wave Rabi flopping in real atoms by employing numerical simulations of high-order harmonic generation (HHG) in alkali species. Given the short HHG cutoff, related to the low saturation intensity, we concentrate on the features of the third harmonic of sodium (Na) and potassium (K) atoms. For pulse areas of 2$\pi$ and Na atoms, a characteristic unique peak appears, which, after analyzing the ground state population, we correlate with the conventional Rabi flopping. On the other hand, for larger pulse areas, carrier-wave Rabi flopping occurs, and is associated with a more complex structure in the third harmonic. These new characteristics observed in K atoms indicate the breakdown of the area theorem, as was already demonstrated under similar circumstances in narrow band gap semiconductors

Report No. 16: Study on the Social and Labour Market Integration of Ethnic Minorities

Report for the High Level Advisory Group on Social and Labour Market Integration of Ethnic Minorities and the European Commission, Bonn 2008 (166 pages) [German version] (Studie über die soziale Eingliederung und Arbeitsmarktintegration ethnischer Minderheiten)

The Threat Effect of Participation in Active Labor Market Programs on Job Search Behavior of Migrants in Germany

Labor market programs may affect unemployed individuals' behavior before they enroll. Such ex ante effects may differ according to ethnic origin. We apply a novel method that relates self-reported perceived treatment rates and job search behavioral outcomes, such as the reservation wage or search intensity, to each other. We compare German native workers with migrants with a Turkish origin or Central and Eastern European (including Russian) background. Job search theory is used to derive theoretical predictions. We examine the omnibus ex ante effect of the German ALMP system, using the novel IZA Evaluation Data Set, which includes self-reported assessments of the variables of interest as well as an unusually detailed amount of information on behavior, attitudes and past outcomes. We find that the ex ante threat effect on the reservation wage and search effort varies considerably among the groups considered.unemployment duration, immigrants, active labor market policy, policy evaluation, reservation wage, program evaluation, expectations, search effort

The threat effect of participation in active labor market programs on job search behavior of migrants in Germany

Labor market programs may affect unemployed individuals’ behavior before they enroll. Such ex ante effects may differ according to ethnic origin. We apply a novel method that relates self-reported perceived treatment rates and job search behav­ioral outcomes, such as the reservation wage or search intensity, to each other. We compare German native workers with migrants with a Turkish origin or Central and Eastern European (including Russian) background. Job search theory is used to de­rive theoretical predictions. We examine the omnibus ex ante effect of the German ALMP system, using the novel IZA Evaluation Data Set, which includes self-reported assessments of the variables of interest as well as an unusually detailed amount of in­formation on behavior, attitudes and past outcomes. We find that the ex ante threat effect on the reservation wage and search effort varies considerably among the groups considered.Immigrants; policy evaluation; reservation wage; search effort; expectations; unemploy­ment duration; program evaluation; active labor market policy.