Computational modelling of the cerebral cortical microvasculature: Effect of x-ray microbeams versus broad beam irradiation.

Microbeam Radiation Therapy is an innovative pre-clinical strategy which uses arrays of parallel, tens of micrometres wide kilo-voltage photon beams to treat tumours. These x-ray beams are typically generated on a synchrotron source. It was shown that these beam geometries allow exceptional normal tissue sparing from radiation damage while still being effective in tumour ablation. A final biological explanation for this enhanced therapeutic ratio has still not been found, some experimental data support an important role of the vasculature. In this work, the effect of microbeams on a normal microvascular network of the cerebral cortex was assessed in computer simulations and compared to the effect of homogeneous, seamless exposures at equal energy absorption. The anatomy of a cerebral microvascular network and the inflicted radiation damage were simulated to closely mimic experimental data using a novel probabilistic model of radiation damage to blood vessels. It was found that the spatial dose fractionation by microbeam arrays significantly decreased the vascular damage. The higher the peak-to-valley dose ratio, the more pronounced the sparing effect. Simulations of the radiation damage as a function of morphological parameters of the vascular network demonstrated that the distribution of blood vessel radii is a key parameter determining both the overall radiation damage of the vasculature and the dose-dependent differential effect of microbeam irradiation

Precautionary Saving and Income Uncertainty in Germany - New Evidence from Microdata

The saving ratio of households in Germany has increased in the past few years when the income trend was weak. This could be due to precautionary saving. In this paper, the importance of precautionary saving against income uncertainty is analyzed empirically using micro data from the German Socio- Economic Panel Study (GSOEP). Wealth in 2002 is regressed on alternative measures of income uncertainty in a cross-section of households. In addition to the usual controls, risk aversion is also taken into account. When using net financial wealth, precautionary saving is statistically significant and economically quite important. The share of precautionary net financial wealth in total aggregate net financial wealth is on average about 20%. Compared with net financial wealth, housing wealth is not used as a buffer stock against income uncertainty, confirming the hypothesis that this kind of asset is rather illiquid

Job Security and Fertility: Evidence from German Reunification

This paper uses the special occupational status of German civil servants in combination with the unforeseen event of German reunification to study empirically the relationship between job security and fertility. The civil servant-status provides extreme job security as well as good possibilities to combine work and family lives. The fast introduction of the civil service system after reunification represents an exogenous (re-)assignment of individual employment risks in Eastern Germany, and thus allows one to control for occupational self-selection. While no strong evidence for a link between job security and fertility emerges for men, the paper demonstrates a clear link between labor market and demographic outcomes for women, especially in Western Germany and most pronounced for higher educated females between age 25 and 40. This strong relationship is the result of occupational self-selection coupled with a civil servantspecific birth timing pattern and a small causal impact of job security on fertility. It shows that female civil servants are not primarily a selected group of very family oriented individuals, but rather both family as well as career oriented.In dieser Studie wird der Einfluss von Arbeitsplatzsicherheit auf die Wahrscheinlichkeit einer Elternschaft untersucht. Dafür wird zum einen der spezielle Status von Beamten in Deutschland und zum anderen das natürliche Experiment der deutschen Wiedervereinigung genutzt. Der Beamtenstatus bietet ein sehr hohes Maß an Arbeitsplatzsicherheit sowie -flexibilität im Hinblick auf die Vereinbarkeit von Berufs- und Familienleben. Die schnelle Einführung des westdeutschen Beamtensystems in Ostdeutschland nach der deutschen Wiedervereinigung kann als exogene Variation im Hinblick auf die Arbeitsplatzsicherheit der dort betroffenen Individuen gesehen werden. Während sich für Männer kein signifikanter Zusammenhang zwischen Arbeitsplatzsicherheit und Fertilität findet, zeigt sich ein solcher für Frauen, insbesondere in Westdeutschland und am stärksten ausgeprägt für höher qualifizierte Frauen im Alter von 25 bis 40 Jahren. Die starke Korrelation zwischen dem Beamtenstatus und einer zukünftigen Elternschaft bei Frauen ist das Resultat von beruflicher Selbstselektion, eines Beamten-spezifischen Geburten-Timings und einem kleinen direkten Effekt von Arbeitsplatzsicherheit auf die Fertilitätsentscheidung. Weiterführende Analysen legen nahe, dass verbeamtete Frauen keine selektierte Gruppe von überaus familienorientierten Individuen darstellen, sondern dass sie vielmehr sowohl familien- als auch karriereorientiert sind. Die empirischen Ergebnisse deuten folglich darauf hin, dass die Vereinbarkeit von Familie und Beruf für Frauen eine wichtige Rolle bei der Berufswahl spielt

Shoe-Leather Costs in the Euro Area and the Foreign Demand for Euro Banknotes

We estimate the shoe-leather costs of inflation in the euro area using monetary data adjusted for holdings of euro banknotes abroad. While we find evidence of marginally negative shoe-leather costs for very low levels of the nominal interest rate, our estimates suggest that the shoe-leather costs are non-negligible even for relatively moderate levels of anticipated inflation. We conclude that, despite the increased circulation of euro banknotes abroad, in the euro area the inflation tax is still predominantly borne by domestic agents, with transfers of resources from abroad remaining small

Job Security Perceptions and the Saving Behavior of German Households

This paper investigates the co-movements of job security perceptions and household saving rates using data from the 1992 to 2010 waves of the German Socio-Economic Panel. The empirical analysis reveals that higher job insecurity is generally accompanied by slightly lower saving which suggests that employment and financial insecurity typically go hand-in-hand. When confounding changes in the perception of financial security are controlled for, slight evidence for precautionary saving behavior is found. This behavior is of rather small economic importance and limited to households that are somewhat worried about their financial situation who increase their saving by about 0.3%-points or EUR 100 annually in the light of increased job insecurity. In contrast, no significant change in saving is observed for households that are either very concerned or not at all concerned about their financial situation, i.e., either financially constrained or in possession of a buffer-stock of wealth.Diese Studie untersucht den Zusammenhang zwischen subjektiv wahrgenommener Arbeitsplatzunsicherheit und dem Sparverhalten deutscher Haushalte mit Daten des Sozio-ökonomischen Panels für den Zeitraum der Jahre 1992 bis 2010. Die empirische Analyse zeigt, dass höher Arbeitsplatzunsicherheit typischerweise mit geringeren Sparquoten einhergeht. Beschäftigungsunsicherheit wird also zumeist von finanzieller Unsicherheit begleitet. Bei Berücksichtigung der finanziellen Situation ergeben sich Anzeichen für Vorsichtssparverhalten. Dieses Verhalten ist allerdings von eher geringer ökonomischer Bedeutung und ist auf Haushalte beschränkt, die etwas über ihre finanzielle Situation besorgt sind. Diese Haushalte erhöhen ihre Sparquote um 0,3 Prozentpunkte oder 100 Euro pro Jahr, wenn sie sich Sorgen um ihren Arbeitsplatz machen. Hingegen lässt sich kein Zusammenhang zwischen Arbeitsplatzunsicherheit und Sparverhalten bei Haushalten finden, die hinsichtlich ihrer finanziellen Lage entweder sehr oder gar nicht besorgt sind, d.h. entweder durch ihr Einkommen restringiert sind oder bereits einen ausreichenden Vermögenspuffer besitzen

Household Savings Decision and Income Uncertainty

This paper empirically investigates the effects of changes in the interest rate as well as transitory income uncertainty on households' consumption-savings decision. Applying a structural demand model to German survey data, we estimate the uncompensated interest rate elasticity for savings, in line with the literature, to around zero. Accordingly, any policy-induced variation of net returns to savings is expected to have no significant effects on the level of savings. Moreover, we find significant effects of precautionary savings on the consumption-savings decision. As a result of a doubling of transitory income uncertainty, an average household increases savings by 4:4%. These effects vary by household composition and social status