High temperature susceptibility in electron doped Ca1-xYxMnO3: Double Exchange vs Superexchange

We present a study of the magnetic properties of the electron doped manganites Ca1-xYxMnO3 (for 0<=x<=0.25) in the paramagnetic regime. For the less doped samples (x<=0.1) the magnetic susceptibility, c(T), follows a Curie-Weiss (CW) law only for T > 450 K and, below this temperature, c^-1(T) shows a ferrimagnetic-like curvature. We approached the discussion of these results in terms of a simple mean-field model where double exchange, approximated by a ferromagnetic Heisenberg-like interaction between Mn3+ and Mn4+ ions, competes with classical superexchange. For higher levels of doping (x>=0.15), the CW behaviour is observed down to the magnetic ordering temperature (Tmo) and a better description of c(T) was obtained by assuming full delocalization of the eg electrons. In order to explore the degree of delocalization as a function of T and x, we analyzed the problem through Montecarlo simulations. Within this picture we found that at high T the electrons doped are completely delocalized but, when Tmo is approached, they form magnetic polarons of large spin that cause the observed curvature in c^-1(T) for x<=0.1.Comment: 15 pages, 10 figures, Submitted to J. Physics: Condensed Matter (06/28/02

Quality of life in Type 1 (insulin-dependent) diabetic patients prior to and after pancreas and kidney transplantation in relation to organ function

Improvement of the quality of life in Type 1 (insulin-dependent) diabetic patients with severe late complications is one of the main goals of pancreas and/or kidney grafting. To assess the influences of these treatment modalities on the different aspects of the quality of life a cross-sectional study in 157 patients was conducted. They were categorized into patients pre-transplant without dialysis (n=29; Group A), pre-transplant under dialysis (n=44; Group B), post-transplant with pancreas and kidney functioning (n=31; Group C), post-transplant with functioning kidney, but insulin therapy (n=29; Group D), post-transplant under dialysis and insulin therapy again (n=15; Group E) and patients after single pancreas transplantation and rejection, with good renal function, but insulin therapy (n=9; Group F). All patients answered a mailed, self-administered questionnaire (217 questions) consisting of a broad spectrum of rehabilitation criteria. The results indicate a better quality of life in Groups C and D as compared to the other groups. In general the scores are highest in C, but without any significant difference to D. Impressive significant differences between C or D and the other groups were found especially in their satisfaction with physical capacity, leisure-time activities or the overall quality of life. The satisfaction with the latter is highest in C (mean±SEM: 4.0±0.2 on a 1 to 5-rating scale; significantly different from A: 3.1±0.1, B: 2.7±0.2 and E: 2.6±0.3; p<0.01), followed by D (3.8±0.2; significantly different from B and E; p<0.01). Group F shows a mean of 3.1±0.4, which is not significantly different from C. The percentages of patients in each group, who are not working: A: 38 %, B: 64 %, C: 74 %, D: 66 %, E: 87 % and F: 78 % indicate that there is no marked improvement in the vocational situation after successful grafting

The Effect of Minimum Wages on Labour Market Flows Evidence from Germany

Using a linked employer-employee data set on the German construction industry, we analyse the effects of the introduction of minimum wages in this sector on labour market dynamics at the establishment level, i.e. turnover and churning flows, as well as accessions and separations and their underlying worker flows. The fact that minimum wages in Germany are sector-specific enables us to apply a between approach using other industries as control groups in a difference-in-differences framework. Furthermore, we use a within approach with high-wage workers as control group. While the within approach shows that the minimum wage reduced worker flows in East Germany, the between approach yields positive effect on labour market dynamics in West Germany. Our results can be explained by differences between East and West Germany with respect to the bite of the minimum wage, as well as the much higher prevalence of posted workers in West Germany. Furthermore, spillover effects to highwage workers are likely to have played a role in East Germany.In dem Papier werden die Auswirkungen der Mindestlohneinführung im deutschen Bauhauptgewerbe auf Arbeitsmarktdynamiken untersucht, wobei die Analyse von Einstellungen und Trennungen sowie der damit zusammenhängenden Arbeitsmarktübergänge auf Betriebsebene erfolgt. Dabei kommt ein einzigartiger Linked Employer-Employee Datensatz zum Einsatz. Da der Mindestlohn zunächst nur im Bauhauptgewerbe eingeführt wurde, können Betriebe einer anderen Branche als Kontrollgruppe in einem Differenz-von-Differenzen-Ansatz genutzt werden (between-Ansatz). Zusätzlich wird ein within-Ansatz verwendet, bei dem Arbeitnehmer mit relativ hohem Lohn innerhalb des Bauhauptgewerbes als Kontrollgruppe dienen. Während der within-Ansatz zeigt, dass der Mindestlohn Arbeiterflüsse in Ostdeutschland reduzierte, bringt der between-Ansatz positive Effekte auf Arbeitsmarktdynamiken in Westdeutschland zutage. Diese Ergebnisse können auf Ost-West-Unterschiede hinsichtlich der Eingriffsintensität des Mindestlohns sowie die deutlich höhere Anzahl entsendeter Arbeitnehmer in Westdeutschland zurückgeführt werden. Zudem sind spillover-Effekte auf Arbeitnehmer mit relativ hohen Löhnen in Ostdeutschland wahrscheinlich

Risk Aversion and the Value of Risk to Life

The standard literature on the value of life relies on Yaari’s (1965) model, which includes an implicit assumption of risk neutrality with respect to life duration. To overpass this limitation, we extend the theory to a simple variety of preferences which are not necessarily additively separable. The enlargement we propose is relevant for the evaluation of life-saving programs: current practice, we estimate, puts too little weight on mortality risk reduction of the young. Our correction exceeds in magnitude that introduced by the switch from the notion of number of lives saved to the notion of years of life saved

How Robust are Simulated Employment Effects of a Legal Minimum Wage in Germany?: A Comparison of Different Data Sources and Assumptions

Several empirical minimum wage studies have recently been published that simulate employment effects of a federal minimum wage in Germany. We disentangle various factors that explain the variation in previous simulation results. Based on data from the German Socio-Economic Panel and the newly available Verdienststrukturerhebung 2006 we conduct robustness analyses that systematically test the range in the outcomes of different labor demand simulations. We find that labor demand effects are sensitive to measurement errors in wages, the representativeness of the sample with respect to several types of labor inputs as well as estimated and assumed labor demand and output price elasticities. Interactions of those determinants may lead to substantial differences in simulation outcomes

Sailing into a dilemma : an economic and legal analysis of an EU trading scheme for maritime emissions

On the basis of a joint economic and legal analysis, we evaluate the effects of a “regional” (European) emission trading scheme aiming at reducing emissions of international shipping. The focus lies on the question which share of emissions from maritime transport activities to and from the EU can and should be included in such a system. Our findings suggest that the attempt to implement an EU maritime ETS runs into a dilemma. It is not possible to design a system that achieves emission reductions in a cost efficient manner and is compatible with international law

Endogenous Growth, Asymmetric Trade and Resource Taxation

Since 1980, the aggregate income of oil-exporting countries relative to that of oil- poor countries has been remarkably constant despite structural gaps in productivity growth rates. This stylized fact is analyzed in a two-country model where resource- poor (Home) and resource-rich (Foreign) economies display productivity differences but stable income shares due to terms-of-trade dynamics. We show that Home's income share is positively related to the national tax on domestic resource use, a prediction confirmed by dynamic panel estimations for sixteen oil-poor economies. National governments have incentives to deviate from both efficient and laissez-faire allocations. In Home, increasing the oil tax improves welfare through a rent-transfer mechanism. In Foreign, subsidies (taxes) on domestic oil use improve welfare if R&D productivity is lower (higher) than in Home

Real Tax Effects and Tax Perception Effects in Decisions on Asset Allocation

We test the predictions of the theoretical literature initiated by the study of Domar and Musgrave (1944) with a laboratory experiment in which subjects have to decide on the composition of an asset portfolio. Our simple design enables us to distinguish between Real Tax Effects and Perception Effects when a proportional income tax, with and without a full loss offset provision, is introduced. Observed investment behavior is partially inconsistent with the theoretical predictions if we do not control for the Perception Effects. However, if we consider these effects, we find support for the theory. The isolated Perception Effects can explain the unexpected behavior observed in previous studies and has both scientific and political implications