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This paper evaluates the effects of Public Sponsored Training in East Germany in the context of reiterated treatments. Selection bias based on observed characteristics is corrected for by applying kernel matching based on the propensity score. We control for further selection and the presence of Ashenfelter's Dip before the program with conditional difference-in-differences estimators. Training as a first treatment shows insignificant effects on the transition rates. The effect of program sequences and the incremental effect of a second program on the reemployment probability are insignificant. However, the incremental effect on the probability to remain employed is slightly positive. JEL - Klassifikation: H43 , C23 , J6 , J64 , C14
The Box-Cox quantile regression model using the two stage method introduced by Chamberlain (1994) and Buchinsky (1995) provides an attractive extension of linear quantile regression techniques. However, a major numerical problem exists when implementing this method which has not been addressed so far in the literature. We suggest a simple solution modifying the estimator slightly. This modification is easy to implement. The modified estimator is still [square root] n-consistent and its asymptotic distribution can easily be derived. A simulation study confirms that the modified estimator works well.
This paper investigates the magnitude and the main determinants of share price reactions to buy-back announcements of German corporations. For our comprehensive sample of 224 announcements that took place between May 1998 and April 2003 we find average cumulative abnormal returns around -7.5% for the thirty days preceding the announcement and around +7.0 % for the ten days following the announcement. We regress post-announcement abnormal returns with multiple firm characteristics and provide evidence which supports the undervaluation signaling hypothesis but not the excess cash hypothesis or the tax-efficiency hypothesis. In extending prior empirical work, we also analyze price effects from initial statements of firms that they intend to seek shareholder approval for a buy-back plan. Observed cumulative abnormal returns on this initial date are in excess of 5% implying a total average price effect between 12% and 15% from implementing a buy-back plan. We conjecture that the German regulatory environment is the main reason why market variations to buy-back announcements are much stronger in Germany than in other countries and conclude that initial statements by managers to seek shareholders’ approval for a buy-back plan should also be subject to legal ad-hoc disclosure requirements.
This paper analyzes empirically the distribution of unemployment durations in West- Germany before and after the changes during the mid 1980s in the maximum entitlement periods for unemployment benefits for elderly unemployed. The analysis is based on the comprehensive IAB employment subsample containing register panel data for about 500.000 individuals in West Germany. We analyze two proxies for unemployment since the data do not precisely measure unemployment in an economic sense. We provide a theoretical analysis of the link between the durations of nonemployment and of unemployment between jobs. Our empirical analysis finds significant changes in the distributions of nonemployment durations for older unemployed individuals. At the same time, the distribution of unemployment durations between jobs did not change in response to the reforms. Our findings are consistent with an interpretation that many firms and workers used the more bene cial laws as a part of early retirement packages but those workers who were still looking for a job did not reduce their search effort in response to the extension of the maximum entitlement periods. This interpretation is consistent with our theoretical model under plausible assumptions. JEL: C24, J64, J65
We show that multi-bank loan pools improve the risk-return profile of banks’ loan business. Banks write simple contracts on the proceeds from pooled loan portfolios, taking into account the free-rider problems in joint loan production. Thus, banks benefit greatly from diversifying credit risk while limiting the efficiency loss due to adverse incentives. We present calibration results that the formation of loan pools reduce the volatility in default rates, proxying for credit risk, of participating banks’ loan portfolios by roughly 70% in our sample. Under reasonable assumptions, the gain in return on equity (in certainty equivalent terms) is around 20 basis points annually.
Global reserves of coal, oil and natural gas are diminishing; global energy requirements however are dramatically increasing. Renewable energy sources lower the threat to the earth’s climate but are not able to meet the energy consumption in major urban areas. The opinion of many experts is that the future will be dominated by hydrogen. However, this gas is essentially totally manufactured from fossil fuels and is hence of limited abundance – not to mention the hazards involved in its utilisation. - A novel energy concept involving solar and thus carbon-independent hydrogen-based technology necessitates an intermediate storage vehicle for renewable energy. This future energy carrier should be simple to manufacture, be available to an unlimited degree or at least be suitable for recycling, be able to store and transport the energy without hazards, demonstrate a high energy density and release no carbon dioxide or other climatically detrimental substances. - Silicon successfully functions as a tailor-made intermediate linking decentrally operating renewable energy-generation technology with equally decentrally organised hydrogen-based infrastructure at any location of choice. In contrast to oil and in particular hydrogen, the transport and storage of silicon are free from potential hazards and require a simple infrastructure similar to that needed for coal.
This paper compares the accuracy of credit ratings of Moody s and Standard&Poors. Based on 11,428 issuer ratings and 350 defaults in several datasets from 1999 to 2003 a slight advantage for the rating system of Moody s is detected. Compared to former research the robustness of the results is increased by using nonparametric bootstrap approaches. Furthermore, robustness checks are made to control for the impact of Watchlist entries, staleness of ratings and the effect of unsolicited ratings on the results.
National borders in Europe have been opening since 1992 and the Union is expanding to embrace more countries prompting enterprises to consider alternative and more attractive locations outside their home country to handle part of their activities (Van Dijk and Pellenbarg, 2000; Cantwell and Iammarino, 2002). International relocation is becoming more and more popular even for small and medium-sized firms that are involved in a growing internationalisation process, mirroring the path of multinational enterprises. Italy, like other industrialised countries, is experiencing a fragmentation of the production chain: firms tend to shift high labour-intensive manufacturing activities to areas characterised by an abundance of low-cost labour (i.e. Central Eastern Europe, India, South East Asia, Latin America, Russia and Central Asia). The internationalisation process by Italian district SMEs has assumed significant dimensions. It has become a relevant topic in recent economic debate because of its consequences for the local context and, in particular, the implication for the survival of the Italian district model (see, among others, Becattini, 2002; Rullani, 1998 and Cor, 2000). The purpose of the paper is twofold: it aims at (i) identifying the managerial approaches to the internationalisation process adopted by the Italian district SMEs and by the Industrial District (ID) itself and (ii) at investigating whether the international delocalisation to the South Eastern European countries (SEECs) constitutes a threat or an opportunity for the Italian district model. The paper is organised as follows. The general introduction is followed by a description of the evolution of the internationalisation processes in Italy over the last three decades. Section three presents a discussion of the internationalisation strategies adopted by Italian SMEs. Section four focuses on the internationalisation process of the Italian industrial districts SMEs. A review of the studies on the subject is offered in section five. Section six presents a qualitative study on the internationalisation process as undergone by sports shoes manufacturers in the Montebelluna district, in north-east Italy. This study shows different managerial strategies to the internationalisation process and emphasises that the motivations can evolve over time, from originally cost-saving to increasingly market-oriented or global strategies. On the basis of a literature review, section seven investigates whether internationalisation constitutes a threat (i.e. loss of jobs and knowledge) or an opportunity (i.e. enlargement of the ID, update district s competitiveness) for the district model. Finally, some summarising remarks in section eight conclude the paper.
The hypothesis that oxidative stress plays a role in the pathogenesis of Alzheimer’s disease (AD) was tested by studying oxidative damage, acitvities of antioxidant enzymes and levels of reactive oxygen species (ROS) in several models. To this end, mouse models transgenic for mutant presenilin (PS1M146L) as well as mutant amyloid precursor protein (APP) and human post mortem brain tissue from sporadic AD patients and age-matched controls were studied. Aging leads to an upregulation of antioxidant enzyme activities of Cu/Zn-superoxide dismutase (Cu/Zn-SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) in brains from C57BL/6J mice. Simultaneously, levels of lipid peroxidation products malondialdehyde MDA and 4-hydroxynonenal HNE were reduced. Additionally, pronounced gender effects were observed, as female mice display better protection against oxidative damage due to higher activity of GPx. Hence, antioxidant enzymes provide an important contribution to the protection against oxidative damage. In PS1M146L transgenic mice oxidative damage was only detectable in 19-22 months old mice, arguing for an additive effect of aging and the PS1 mutation. Both HNE levels in brain tissue as well as mitochondrial and cytosolic levels of ROS in splenic lymphocytes were increased in PS1M146L mice. Antioxidant defences were unaltered. In PDGF-APP and PDGF-APP/PS1 trangenic mice no changes in any of the parameters studied were observed in any age group. In contrast, Thy1-APP transgenic mice display oxidative damage as assessed by increased HNE levels. Reduced activity of Cu/Zn-SOD may explain this observation. Additionally, gender modified this effect, as female APP transgenic mice display higher b-secretase cleavage of APP and simultaneously increased HNE levels and reduced Cu/Zn-SOD activity earlier than male mice, i.e. from an age of 3 months and before the formation of Ab plaques. Reduced Cu/Zn-SOD activity was also found in another APP transgenic mouse model, in APP23 mice. In post mortem brain tissue from sporadic AD patients activities of Cu/Zn-SOD and GPx were however increased, and changes were most pronounced in temporal cortex. Simultaneously, levels of HNE but not MDA were elevated. Additionally, in vitro stimulation of lipid peroxidation led to increased MDA formation in samples from AD patients, indicating that increased activity of Cu/Zn-SOD and GPx are insufficient to protect against oxidative damage. Furthermore, the observed changes were subject to a gender effect, as samples from female AD patients showed increased activities of Cu/Zn-SOD and GPx as well as increased HNE levels, indicating that brain tissue from females is more sensitive towards oxidative damage. Levels of soluble Ab1-40 were positively correlated with with MDA levels and activities of Cu/Zn-SOD and GPx. Additionally, levels of lipid peroxidation products MDA and HNE are gene-dose-dependently modulated by the Apolipoprotein E4 allele, the most important genetic risk factor for AD known so far. While MDA levels were negatively correlated with MMSE scores, a measure for cognitive function, HNE levels were highest in AD patients with moderate cognitive impairment. Hence, increased HNE levels may play an important role in neurodegenerative events at an early disease stage. In summary, oxidative damage, as assessed by increased HNE levels, could be detected in sporadic AD patients and in different transgenic mouse models. The results of this thesis therefore support the further research of pharmacological targets aiming at augmentation of antioxidant defences for therapy or prophylaxis of Alzheimer’s disease.
The cytochrome bc1 complex is a cornerstone in bioenergetic electron transfer chains, where it carries out tasks as diverse as respiration, photosynthesis, and nitrogen fixation. This homodimeric multisubunit membrane protein has been studied extensively for several decades and the enzyme mechanism is described with the modified protonmotive Q cycle. Still, the molecular and kinetic description of the catalytic cycle is not complete and questions remain regarding the bifurcation of electron transfer at the quinol oxidation (Qo) site, substrate occupancy, pathways of proton conduction, and the nature of the Rieske protein domain movement. We used competitive inhibitors to study the molecular architecture at the Qo site with X-ray crystallography. The structure of the enzyme with the substrate analog 5-n-heptyl-6-hydroxy-4,7-dioxobenzothiazole (HHDBT) bound at the Qo site was determined at 2.5 Å resolution. Spectroscopic studies showed that HHDBT is negatively charged when bound at the active site. Mechanistic interpretations from inhibitor binding are in line with single occupancy model for quinol oxidation and structural analysis supports the proposed proton transfer pathway. For functional insight into the enzyme mechanism, redox-sensitive protonation changes were studied by Fourier transform infrared spectroscopy. The protein purification procedure was optimized for less delipidation and the isolated enzyme was more active. Furthermore, two new phospholipids were identified in the X-ray structures, including a cardiolipin. Strikingly, conserved lipid binding cavities were observed in structural comparison with homologous enzymes. The functional role of tightly bound phospholipids will be discussed. Finally, the Qo site is a target for various compounds of agricultural and pharmaceutical importance. Importantly, the X-ray structures permit detailed analysis of the molecular reasons for acquired resistance to and treatment failure of Qo site inhibitors, such as atovaquone, that is used to treat malaria and pneumonia, as discussed herein.