Modeling Take-or-Pay Contract Decisions

Long-term purchase contracts for natural resources, such as natural gas, often contain take-or-pay provisions that penalize the buyer for not purchasing (taking) a minimum quantity of output over some period of time. In some contracts for a limited time interval, known as the make-up period, the penalty payments can be credited against future “takes” in excess of the take-or-pay level. Additionally, options to “buy down” or “buy out” existing contracts, or to initiate new contracts, may exist. The purchaser, faced with projected requirements over some planning horizon, must determine purchase levels from a selected set of take-or-pay contracts so as to minimize purchase, inventory holding, penalty costs, contract initiation, and buy-out or buy-down costs. This paper presents a mixed-integer programming model of take-or-pay decisions with and without make-up provisions.     

Permanent Disadvantage or Gradual Integration: Explaining the Immigrant–Native Earnings Gap in Sweden

Theoretical explanations suggest that wage differentials between immigrant and native workers are generated either by differences in the acquisition of human capital or by various forms of exclusion of immigrants from fair labour market rewards. We evaluate the labour quality and labour market discrimination hypotheses by using a large sample of Swedish employees in 1995. Our findings show that labour market integration is relatively unproblematic for immigrants from Western countries, whereas immigrants from other countries, especially from Africa, Asia and Latin America, face substantial obstacles to earnings progress when entering the Swedish labour market. For the latter group of countries, extensive controls for general and country‐specific human capital reduce the earnings differentials. However, the remaining gap is of a non‐trivial magnitude. Thus, the labour quality hypothesis accounts for a part of the observed native–immigrant wage gap, but the remaining differentials can be interpreted in terms of labour market discrimination.     

Relationship course theory: An interdisciplinary integrative proposition to address the complexification of interpersonal relationships

Researchers have been observing a complexification of interpersonal relationships in contemporary societies. However, current theoretical perspectives on relationships fall short of comprehensively grasping increasingly diverse and fluid relationship types (e.g., friends with benefits, polyamory, living-apart-together, coparenting, etc.) and patterns of change. In an attempt to meet the need for more integrative and interdisciplinary theorizing, this paper introduces a first outline of relationship course theory to better comprehend the complexity of relationships. In contrast to previous theoretical perspectives that conceptualize relationships as a single trajectory, I posit that the course of a relationship is composed of multiple intertwined trajectories, each of which stemming from differentiated domains such as sexuality, friendship, love, family, domesticity, and occupation. These relationship domains constitute a metatypology from which to examine the multiple sets of meanings and temporalities that intertwine throughout the course of a relationship. I propose that relationships are defined based on the combination of relationship domains, with different iterations and permutations of these domains producing various relationship configurations. Furthermore, the theory defines three levels of relationship courses: Sociocultural (i.e., stories that circulate about relationships in given sociocultural contexts), interpersonal (i.e., stories that individuals co-construct about the particular relationships they experience), and life courses (i.e., stories that individuals co-construct about themselves as relational beings). This proposition will hopefully stimulate the theoretical conversation on the complexity of relationships and foster dialogue between researchers from different theoretical and disciplinary affiliations.