A hybrid graphene-siliconnitride nanomembrane as a versatile and ultra-widely tunable mechanical device

Integration of 2D materials in nanoelectromechanical systems (NEMS) marries the robustness of silicon-based materials with exceptional electrical controllability in 2D materials, drastically enhancing system performance which now is the key for many advanced applications in nanotechnology. Here, we experimentally demonstrate and theoretically analyze a powerful on-chip graphene integrated NEMS device consisting of a hybrid graphene/silicon-nitride membrane with metallic leads that enables an extremely large static and dynamic parameter regulation. When a static voltage is applied to the leads, the force induced by the thermal expansion difference between the leads and the membrane results in ultra-wide frequency tuning, deformation (post-buckling transition) and regulation of mechanical properties. Moreover, by injecting an alternating voltage to the leads, we can excite the resonator vibrating even far beyond its linear regime without a complex and space consuming actuation system. Our results prove that the device is a compact integrated system possessing mechanical robustness, high controllability, and fast response. It not only expands the limit of the application range of NEMS devices but also pushes multidimensional nanomechanical resonators into working in the nonlinear regime

Gender-Specific Effects of Unemployment on Family Formation: A Cross-National Perspective

This paper investigates the impact of unemployment on the propensity to start a family. Unemployment is accompanied by bad occupational prospects and impending economic deprivation, placing the well-being of a future family at risk. I analyze unemployment at the intersection of state-dependence and the reduced opportunity costs of parenthood, distinguishing between men and women across a set of welfare states. Using micro-data from the European Community Household Panel (ECHP), I apply event history methods to analyze longitudinal samples of first-birth transitions in France, Finland, Germany, and the UK (1994-2001). The results highlight spurious negative effects of unemployment on family formation among men, which can be attributed to the lack of breadwinner capabilities in the inability to financially support a family. Women, in contrast, show positive effects of unemployment on the propensity to have a first child in all countries except France. These effects prevail even after ontrolling for labour market and income-related factors. The findings are pronounced in Germany and the UK where work-family conflicts are the cause of high opportunity costs of motherhood, and the gender-specific division of labour is still highly traditional. Particularly among women with a moderate and low level of education, unemployment clearly increases the likelihood to have a first child

Women’s Fertility and Employment Decisions Under Two Political Systems – Comparing East and West Germany Before Reunification

Over the last decades fertility rates have decreased in most developed countries, while female labour force participation has increased strongly over the same time period. To shed light on the relationship between women's fertility and employment decisions, we analyse their transitions to the first, second, and third child as well as their employment discontinuities following childbirth. Using new longitudinal datasets that cover the work and family life of women in the Federal Republic of Germany (FRG) and the German Democratic Republic (GDR) allows for taking into account two political regimes and drawing conclusions about the relevance of institutional factors for fertility and employment decisions. Our results suggest that in both parts of Germany women's probability of having a first child is negatively correlated with both employment and educational achievement. Regarding second and third birth risks, this negative correlation weakens. Analysing women's time spent out of the labour market following childbirth we find that in the East almost all mothers return to work within 18 months after birth. In the West, however, this proportion is much smaller and at the age when the child starts nursery school or school, women re-enter the labour market at higher rates. These results point to a strong influence of institutional circumstances, specifically the extent of public daycare provision. A multivariate analysis reveals a strong correlation between a woman's employment status prior to birth and her probability of re-entering the labour market afterwards