Assessing schematic knowledge of introductory probability theory

[Abstract]: The ability to identify schematic knowledge is an important goal for both assessment and instruction. In the current paper, schematic knowledge of statistical probability theory is explored from the declarative-procedural framework using multiple methods of assessment. A sample of 90 undergraduate introductory statistics students was required to classify 10 pairs of probability problems as similar or different; to identify whether 15 problems contained sufficient, irrelevant, or missing information (text-edit); and to solve 10 additional problems. The complexity of the schema on which the problems were based was also manipulated. Detailed analyses compared text-editing and solution accuracy as a function of text-editing category and schema complexity. Results showed that text-editing tends to be easier than solution and differentially sensitive to schema complexity. While text-editing and classification were correlated with solution, only text-editing problems with missing information uniquely predicted success. In light of previous research these results suggest that text-editing is suitable for supplementing the assessment of schematic knowledge in development

Essays in Sovereign Credit Risk

This dissertation investigates aspects of sovereign credit risk in advanced and emerging economies. It consists of two chapters. Chapter 1 studies the determinants of sovereign credit default swap (CDS) spreads for 16 advanced economies during the recent financial crisis. We document that the state of the world financial system, and since the beginning of the crisis, the state of a country’s domestic financial system, have strong explanatory power for the behavior of CDS spreads. Furthermore, the magnitude of this effect depends on the relative importance of a country\u27s financial system pre-crisis. Our results suggest the presence of a private-to-public risk transfer through which market participants incorporate their expectations about the potential burden of government intervention. Chapter 2 studies the extent to which macro-economic variables govern the dynamics of emerging market sovereign CDS spreads. In this chapter, I propose a structural model of sovereign credit risk based on a country\u27s access to international capital flows through exports, imports and international reserves. The joint dynamics of the sovereign’s repayment capacity and the amount of outstanding debt determine the level of default risk and thus the sovereign CDS spread. I implement the model for a sample of six emerging economies for a period covering the recent financial crisis. A calibrated version of the model captures the widening of sovereign spreads during the crisis and provides a good fit for their time-series dynamics. Lastly, I find that the market-implied level of country liabilities is on average 13% larger than the reported level of debt

How should fishing mortality be distributed under balanced harvesting?

Zhou and Smith (2017) investigate different multi-species harvesting scenarios using a simple Holling-Tanner model. Among these scenarios are two methods for implementing balanced harvesting, where fishing is distributed across trophic levels in accordance with their productivity. This note examines the effects of a different quantitative implementation of balanced harvesting, where the fishing mortality rate is proportional to the total production rate of each trophic level. The results show that setting fishing mortality rate to be proportional to total production rate, rather than to productivity per unit biomass, better preserves trophic structure and provides a crucial safeguard for rare and threatened ecological groups. This is a key ingredient of balanced harvesting if it is to meet its objective of preserving biodiversity

Rmi1 stimulates decatenation of double Holliday junctions during dissolution by Sgs1-Top3

double Holliday junction (dHJ) is a central intermediate of homologous recombination that can be processed to yield crossover or non-crossover recombination products. To preserve genomic integrity, cells possess mechanisms to avoid crossing over. We show that Saccharomyces cerevisiae Sgs1 and Top3 proteins are sufficient to migrate and disentangle a dHJ to produce exclusively non-crossover recombination products, in a reaction termed "dissolution." We show that Rmi1 stimulates dHJ dissolution at low Sgs1-Top3 protein concentrations, although it has no effect on the initial rate of Holliday junction (HJ) migration. Rmi1 serves to stimulate DNA decatenation, removing the last linkages between the repaired and template DNA molecules. Dissolution of a dHJ is a highly efficient and concerted alternative to nucleolytic resolution that prevents crossing over of chromosomes during recombinational DNA repair in mitotic cells and thereby contributes to genomic integrity