The development of amyloid beta protein deposits in the aged brain

The deposition of amyloid beta protein (Abeta) in the human brain and the generation of neurofibrillary tangles are the histopathological hallmarks of Alzheimer's disease. Accumulation of Abeta takes place in senile plaques and in cerebrovascular deposits as a result of an imbalance between Abeta production and clearance. This Review describes the different types of Abeta deposits, which can be distinguished by their morphology and by the hierarchical involvement of distinct areas of the brain in Abeta deposition. The role of intracellular Abeta in Abeta deposition and the mechanism of Abeta toxicity are also discussed.     

Die Identifizierung von Lead Usern über soziale Netzwerke: Eine empirische Untersuchung unter jungen Konsumenten

In recent years, the lead user concept has received a great deal of attention in both academic research and corporate practice. Despite broad empirical evidence regarding the high potential of lead users for new product development, we still lack a full understanding of their nature and what enables individual consumers to become lead users. Our study addresses these fundamental issues in lead user research and examines them from a perspective which focuses on the social context of individual consumers. This angle is promising and fruitful as individual creative processes are couched in social networks. As a result, our investigation is guided by the following research question: Do lead users have a distinct social ‘footprint’ in social networks? We chose 34 groups of 804 young consumers as the empirical setting for our study, which yields two general findings: First, lead users are positioned as bridging links between different clusters of people. Being in this ‘boundary-spanning’ position implies that lead users have a wider reach and variety in receiving and distributing information and knowledge. Second, this finding is robust across different age groups. The insights from our study contribute to developing new means of identifying lead users in different settings, including Web 2.0 communities.     

Is the German apprenticeship system a panacea for the U.S. labor market?

This paper explores the structure of incentives undergirding the German system of apprenticeship training. We first describe characteristics of the German labor market which may lead firms to accept part of the cost of general training, even in the face of worker turnover. We then compare labor market outcomes for apprentices in Germany and high school graduates in the United States. Apprentices in Germany occupy a similar position within the German wage structure as held by high school graduates in the United States labor market. Finally, we provide evidence that – in both countries – the problem of forming labor market bonds is particularly acute for minority youth. JEL classification: J24, J31, J60 Received: July 4, 1996 / Accepted February 4, 1997     

Ein Ansatz zur Verbesserung der Steuerung des Zahlungsausfallrisikos im E-Commerce (B-to-C)

In recent years, the situation of e-commerce in Germany especially in the retail sector has not only been characterized by a sustained growth in sales but also by an increase in deficits in payment. Companies considering a general exclusion of risky payment methods to be suboptimal are challenged by an adequate assessment of their prospective customers’ risk of payment default. Thereby, inability and unwillingness to pay has to be considered as possible reasons on a transactional basis and in real-time. This paper presents a new approach combining common methods for risk identification and assessment. Case studies show that a more sophisticated risk control can be achieved by applying the approach presented.     

Relative efficiency of first difference estimator in panel data regression with serially correlated error components

We consider the pooled cross-sectional and time series regression model when the disturbances follow a serially correlated one-way error components. In this context we discovered that the first difference estimator for the regression coefficients is equivalent to the generalized least squares estimator irrespective of the particular form of the regressor matrix when the disturbances are generated by a first order autoregressive process where the autocorrelation is close to unity.     

Central versus Local Service Regulation: Accounting for Diverging Old-age Care Developments in Sweden and Denmark, 1980–2000

In Sweden and Denmark, the development of old‐age care has followed markedly divergent paths over the past 20 years. In both countries, the level of old‐age care universalism was exceptionally high in the early 1980s. Since then it has dropped sharply in Sweden, while remaining constantly high in Denmark. These divergent trends are clearly irreconcilable with the common image of a coherent Scandinavian welfare state model, and they seem hard to explain with reference to traditional approaches of comparative social policy. This article attempts to account for the divergent developments by focusing on the balance of old‐age care regulation between central and local government. The main finding is that only in Sweden has the central regulation of old‐age care been weak and unspecific. As a consequence, Swedish municipalities have enjoyed sufficient autonomous, regulatory competence to exercise certain local retrenchment measures in times of austerity, thereby eventually causing a nationwide weakening of old‐age care universalism. By contrast, municipalities in Denmark have been much more tightly bound by central state regulations which have prevented them from imposing similar retrenchment measures in the old‐age care sector; consequently, Denmark's level of old‐age care universalism has remained comparatively high.     

Laughter in Conversation: Features of Occurrence and Acoustic Structure

Although human laughter mainly occurs in social contexts, most studies have dealt with laughter evoked by media. In our study, we investigated conversational laughter. Our results show that laughter is much more frequent than has been described previously by self-report studies. Contrary to the common view that laughter is elicited by external stimuli, participants frequently laughed after their own verbal utterances. We thus suggest that laughter in conversation may primarily serve to regulate the flow of interaction and to mitigate the meaning of the preceding utterance. Conversational laughter bouts consisted of a smaller number of laughter elements and had longer interval durations than laughter bouts elicited by media. These parameters also varied with conversational context. The high intraindividual variability in the acoustic parameters of laughter, which greatly exceeded the parameter variability between subjects, may thus be a result of the laughter context.