The following dissertation is a collection of four stand-alone research papers. The focus of my research is on the interplay of immigration, native human-capital investment and the resulting consequences for the labour market outcome of natives and necessary implications for the immigration...

Commodity and energy prices have exhibited an unprecedented increase between October 2006 and July 2008, only to fall sharply during the last months of 2008. Many explanations have been offered to this phenomenon, including steadily increasing demand from China and India, large mandated...

For seventy years ecologists have debated to what extent competition affects the composition of ecological communities. At one extreme, species have been proposed to assemble independently of each other, while at the other extreme, competition and other interspecific interactions have been...

A Bayes net has qualitative and quantitative aspects: The qualitative aspect is its graphical structure that corresponds to correlations among the variables in the Bayes net. The quantitative aspects are the net parameters. This paper develops a hybrid criterion for learning Bayes net structures...

As disease spreads through a population, scientists want to know who gets sick, how bestto prevent a large outbreak, and if an epidemic may occur. For many years, mathematicians usedmodels to approximate answers to these questions; however, these older models used simplifyingassumptions about...

Transcribing medical documents accurately into pre-defined formats and within certain time frames is vital for administrative and medical purposes in any hospital. This paper describes quantitative models incorporating available data to represent transcription activities of a medical records...

In this thesis, several stochastic optimization models are presented to determine the number of airport arrival slots that should be made available for distribution via a market mechanism. Considerable attention is paid to the structure and mathematical properties of each of these models, with...

CMPL (Coliop Mathematical Programming Language) is a mathematical programming language for modelling linear programming (LP) problems or mixed integer programming (MIP) problems. The CMPL syntax is similar in formulation to the the original mathematical model but also includes syntactic elements...

Struggling retail chains often try to recover profitability by closing some of their stores. The challenge in this strategy lies in determining how many stores to close, as store exit has implications for both the customers and the supply chain. After a store closes, its customers are lost...

Drei große Reformenpakete und eine Reihe kleinerer Begleitmaßnahmen prägen das renten¬politische Erbe der rot-grünen Bundesregierung. Einerseits greifen sie Trends in der Reformpolitik seit Beginn der 90er Jahre auf. So verstärkt die Rentenstrukturreform 2001 beispielsweise die...