Lernprozesse dokumentieren, reflektieren und beurteilen. Lerntagebuch und Portfolio in Bildungsforschung und Bildungspraxis

Die Beiträge greifen "den Wandel von einer Lehr- hin zu einer Lernkultur" auf und konzentrieren sich dabei auf "zwei Indikatoren dieses Wandels: die Einführung von Lerntagebüchern und die Implementierung von Portfolios im Bildungsbereich, und zwar im schulischen Unterricht, in der Lehrer-Grundausbildung sowie in der Weiterbildung. Der Lerntagebuch- und Portfolio-Ansatz implizieren eine bestimmte Haltung gegenüber dem Lernen und Lehren. Der Einsatz von Tagebüchern und Portfolios führt Lehrende dazu, ihren Unterricht für neue Zugänge zu öffnen und ihre Rolle als Lernbegleiter/innen und -berater/innen zu professionalisieren. Andererseits erfordern Tagebücher und Portfolios von Lernenden eine aktive, selbstreflexive und eigenverantwortliche Auseinandersetzung mit ihrem Lernprozess. In diesem Band werden zum einen praxisbezogene Erfahrungen, zum anderen aktuelle Erkenntnisse aus der Forschung zum Potenzial des Lerntagebuch- und Portfolio-Ansatzes präsentiert. Jeweils drei bis fünf Beiträge zum Kontext Schule, Hochschule und Weiterbildung sind drei Hauptteilen zugeordnet: 1. Grundüberlegungen zur neuen Lernkultur und zur Arbeit mit Lerntagebuch bzw. Portfolio; 2. Lerntagebücher in Forschung und Praxis; 3. Portfolios in Forschung und Praxis.

Heterogeneous Beliefs and the Demand for D&O Insurance by Listed Companies

This paper introduces a new rationale for the existence of “Directors’ and Officers’” (D&O) insurance. We use a model with volatile stock markets where shareholders design compensation schemes that incentivize managers to stimulate short-term increases in stock prices that do not maximize long run stock market value. We show that D&O insurance provides a convenient instrument for the initial shareholders of a company to take advantage of differences in beliefs between insiders and outsiders in capital markets. The empirical results support the idea that both the insurance coverage and the premium are higher in the presence of new shareholders and volatile markets. The results prove robust in various empirical model specifications.

Predictors of Weight Loss Maintenance following an Insurance-Sponsored Weight Management Program

Intentional weight loss among overweight and obese adults (body mass index ≥ 25 kg/m2) is associated with numerous health benefits, but weight loss maintenance (WLM) following participation in weight management programming has proven to be elusive. Many individuals attempting to lose weight join formal programs, especially women, but these programs vary widely in focus, as do postprogram weight regain results. We surveyed 2,106 former participants in a community-based, insurance-sponsored weight management program in the United States to identify the pre, during, and post-intervention behavioral and psychosocial factors that lead to successful WLM. Of 835 survey respondents (39.6% response rate), 450 met criteria for inclusion in this study. Logistic regression analyses suggest that interventionists should assess and discuss weight loss and behavior change perceptions early in a program. However, in developing maintenance plans later in a program, attention should shift to behaviors, such as weekly weighing, limiting snacking in the evening, limiting portion sizes, and being physically active every day.

Portfolio-optimization models for small investors

Since 2010, the client base of online-trading service providers has grown significantly. Such companies enable small investors to access the stock market at advantageous rates. Because small investors buy and sell stocks in moderate amounts, they should consider fixed transaction costs, integral transaction units, and dividends when selecting their portfolio. In this paper, we consider the small investor’s problem of investing capital in stocks in a way that maximizes the expected portfolio return and guarantees that the portfolio risk does not exceed a prescribed risk level. Portfolio-optimization models known from the literature are in general designed for institutional investors and do not consider the specific constraints of small investors. We therefore extend four well-known portfolio-optimization models to make them applicable for small investors. We consider one nonlinear model that uses variance as a risk measure and three linear models that use the mean absolute deviation from the portfolio return, the maximum loss, and the conditional value-at-risk as risk measures. We extend all models to consider piecewise-constant transaction costs, integral transaction units, and dividends. In an out-of-sample experiment based on Swiss stock-market data and the cost structure of the online-trading service provider Swissquote, we apply both the basic models and the extended models; the former represent the perspective of an institutional investor, and the latter the perspective of a small investor. The basic models compute portfolios that yield on average a slightly higher return than the portfolios computed with the extended models. However, all generated portfolios yield on average a higher return than the Swiss performance index. There are considerable differences between the four risk measures with respect to the mean realized portfolio return and the standard deviation of the realized portfolio return.

Land use imperils plant and animal community stability through changes in asynchrony rather than diversity

Human land use may detrimentally affect biodiversity, yet long-term stability of species communities is vital for maintaining ecosystem functioning. Community stability can be achieved by higher species diversity (portfolio effect), higher asynchrony across species (insurance hypothesis) and higher abundance of populations. However, the relative importance of these stabilizing pathways and whether they interact with land use in real-world ecosystems is unknown. We monitored inter-annual fluctuations of 2,671 plant, arthropod, bird and bat species in 300 sites from three regions. Arthropods show 2.0-fold and birds 3.7-fold higher community fluctuations in grasslands than in forests, suggesting a negative impact of forest conversion. Land-use intensity in forests has a negative net impact on stability of bats and in grasslands on birds. Our findings demonstrate that asynchrony across species—much more than species diversity alone—is the main driver of variation in stability across sites and requires more attention in sustainable management.