This article analyses the changing division of housework between husbands and wives in western Germany. Using representative longitudinal data from the Bamberg Panel Study of Married Couples, the authors analyse how the division of household labour changes over the first 14 years of marriage. In particular, they assess when and under what conditions the husband's share of traditionally 'female' housework increases or decreases. They consider shifts in spouses' employment hours, relative earnings and family transitions as time-varying predictor variables in event-history models. It is found that almost half of all newlyweds begin by sharing household tasks equally. But over the course of marriage, the husband's contribution to housework declines significantly, mostly independent of spouses' income or working hours. The husband increasing his share of housework is uncommon, even when the wife works longer hours or realizes higher earnings. Traditional gender norms seem to trump earnings. This is particularly true when children are born.

Data from an online dating platform are used to study the importance of education for initiating and replying to online contacts. We analyse how these patterns are influenced by educational homophily and opportunity structures. Social exchange theory and mate search theory are used to explain online mate selection behaviour. Our results show that educational homophily is the dominant mechanism in online mate choice. Similarity in education significantly increases the rate of both sending and replying to initial contacts. After controlling for the opportunity structure on the platform, the preference for similar educated others is the most important factor, particularly among women. Our results also support the exchange theoretical idea that homophily increases with educational level. If dissimilarity contacting patterns are found, women are highly reluctant to contact partners with lower educational qualifications. Men, in contrast, do not have any problems to contact lower-qualified women. Studies of educational homogamy generally show that couples where women have a higher level of education are rare. Our study demonstrates that this is mainly the result of women's reluctance to contact lower qualified men.

We would like to thank Patrick Bolton, Ben Olken and seminar participants at the LSE-UCL development workshop, Columbia and Warwick University. In addition, Vikrant Vig would like to thank the RAMD research grant at the London Business School for their generous support. Kyle Matoba and Jane Zhao provided excellent research assistance. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peerreviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.

A massive, but light abelian U (1) gauge boson is a well motivated possible signature of physics beyond the Standard Model of particle physics. In this paper, the search for the signal of such a U (1) gauge boson in electron-positron pair-production at the spectrometer setup of the A1 Collaboration at the Mainz Microtron (MAMI) is described. Exclusion limits in the mass range of 40 MeV/c 2 up to 300 MeV/c 2 with a sensitivity in the mixing parameter of down to 2 = 8 × 10 −7 are presented. A large fraction of the parameter space has been excluded where the discrepancy of the measured anomalous magnetic moment of the muon with theory might be explained by an additional U (1) gauge boson.