Some applications of the quantum cell model

Ph.D.Harold A. Gersc

Essays on default, entrepreneurship, and institutional arrangements

This dissertation consists of three chapters on the implications of the personal default option on the economy. In the first two chapters, I analyze how credit constraints faced by entrepreneurs are shaped by the legal environment for default that they face. In the third chapter, I explore the welfare implications of allowing financial intermediaries to charge different interest rates according to perceived probabilities of consumer bankruptcy. In the first chapter, I build a model where agents can pick a career and decide whether to default on their mortgage. The purpose of this model is to analyze the interaction between these decisions and the existence of different legal environments, regarding the degree of recourse that lenders have over the borrowers’ assets. The model yields three basic predictions. First, as lenders have more recourse, the cost of default for the borrower increases and default becomes less frequent. Second, as lenders have more recourse, the entrepreneurship threshold (i.e. the amount of home equity a homeowner requires to become an entrepreneur) also increases. Third, where lenders have relatively less recourse, the size of the entrepreneurship threshold reduction due to a house price increase is larger. In the second chapter I test the validity of the third prediction of the model, which encompasses the other two. Using U.S. data, I find that the margins of creation for small young firms responded strongly to the increase in house prices between 2000 and 2007. This effect was driven by those areas where mortgage default is relatively less costly (less recourse). This link between house prices and entrepreneurial activity becomes weaker after the Great Recession. The third chapter explores the effects of allowing financial intermediaries to charge different interest rates according to the debt profile of agents. It also studies the welfare implications of different bankruptcy schemes and those associated with removing the default option. My findings indicate that allowing for price discrimination and removing the bankruptcy option are both desirable. However, the welfare gain from a more stringent bankruptcy regulation is negligible compared to those of removing the bankruptcy option and allowing discrimination

Key features of a succesful invasive macroalgae: the case of asparagopsis taxiformis in Alboran Sea

Asparagopsis taxiformis (Bonnemaisoniales, Rhodophyta) is considered one of the most invasive seaweeds in the Mediterranean, and is included in the spanish checklist of invasive species. Recorded for first time in Southern Spain nearly twenty years ago, we are now ready to highlight its key features to have become a successful invader in Alboran Sea. Genetic studies showed that only one lineage of this species complex, is invasive in Alboran Sea, the lineage 2, which exhibits a wide physiological plasticity, exhibited in a wide thermal adaptation of performances of photosynthetic parameters like Pmax and α. Furthermore, the species is able to inhabit from shallow subtidal up to depths over -30m, due to its low Ic. The species exhibits a trigenetic life-cycle, with an invasive gametophyte dominating the host community, and a free-living tetrasporophyte (Falkenbergia phase) being the dispersal one. The gametophyte is present all the year round, and exhibits a high recruitment and vegetative growth capacity, which support more than 90% of the community biomass. Furthermore, sexual reproduction was perfomed during the whole year, except in winter months, accounting in summer months with more than 50% of the population with reproductive structures. Minimum size for reproduction was low (4-6 cm), considering the maximal size observed for the species in the study site (30 cm). Statistical anaylisis has shown no relationship of reproduction with environmental factors, such as nutrients or temperatura. These features, together with some other more, become A. taxiformis in an invasive species already well settled in Alboran Sea.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech