An investigation of order release and flow time allowance policies for assembly job shops

The effects of a number of essentially different work order release and flow time allowance policies on the assembly order flow times and assembly order due date performance are investigated. Work orders within an assembly order have different routing length. The assembly order flow time is the time that elapses between the release of the first work order and the completion of the last work order of the assembly order. The timing of the release of work orders, and the distribution of the flow time allowance over the work orders in an assembly order were varied, and used systematic computer simulation to investigate the effects on performance. The results show that the best performance is obtained with simultaneous work order release, an average operation flow time allowance equal to the average operation waiting time and equalized flow time allowances per work order in an assembly order.     

A minimally informative likelihood for decision analysis: Illustration and robustness

The authors discuss a class of likelihood functions involving weak assumptions on data generating mechanisms. These likelihoods may be appropriate when it is difficult to propose models for the data. The properties of these likelihoods are given and it is shown how they can be computed numerically by use of the Blahut-Arimoto algorithm. The authors then show how these likelihoods can give useful inferences using a data set for which no plausible physical model is apparent. The plausibility of the inferences is enhanced by the extensive robustness analysis these likelihoods permit.     

Marriage contracts and the law-and-economics of marriage: an Austrian perspective

Marriages and firms share many characteristics in common. Both institutions deal with a set of promises between two parties and therefore need contracts to encourage individual parties to stand by their promises and commitments. Despite these similarities, in most countries marriage laws are statutory laws that have little in common with commercial contract laws. We present the Chicago and neoclassical perspectives on law-and-economics, with a special emphasis on marriage laws. According to this framework, it is possible to explain the way traditional marriage laws have regulated exchanges between spouses and spouses in Western countries such as France, when these countries were patriarchal societies. We also consider the case of egalitarian marriage and show some of the limitations of any statutory marriage laws. We then present a critical perspective on the law-and-economics literature on marriage. Our critique is based on the economic literature by Austrian economists and by public choice theorists. We emphasize the knowledge problem, the problem of interest, and the problems associated with government monopoly in coercion. Our concluding section presents some suggestions regarding a legal system inspired from international commercial contract law. By not giving any particular government a monopoly on the power to enforce marriage contracts such system would avoid some of the problems found in the systems of statutory laws currently regulating marriage and divorce in the Western world.     

Slope heuristics: overview and implementation

Model selection is a general paradigm which includes many statistical problems. One of the most fruitful and popular approaches to carry it out is the minimization of a penalized criterion. Birgé and Massart (Probab. Theory Relat. Fields 138:33–73, 2006) have proposed a promising data-driven method to calibrate such criteria whose penalties are known up to a multiplicative factor: the “slope heuristics”. Theoretical works validate this heuristic method in some situations and several papers report a promising practical behavior in various frameworks. The purpose of this work is twofold. First, an introduction to the slope heuristics and an overview of the theoretical and practical results about it are presented. Second, we focus on the practical difficulties occurring for applying the slope heuristics. A new practical approach is carried out and compared to the standard dimension jump method. All the practical solutions discussed in this paper in different frameworks are implemented and brought together in a Matlab graphical user interface called capushe. Supplemental Materials containing further information and an additional application, the capushe package and the datasets presented in this paper, are available on the journal Web site.     

The results framework--an innovative tool for program planning and evaluation.

This article constitutes a case study of the development and implementation of the "results framework," an innovative planning and evaluation tool that is rapidly becoming a standard requirement for United States Agency for International Development (USAID) projects. The framework is used in a USAID-funded regional initiative for HIV/AIDS prevention in Central America. This new program evaluation and monitoring tool provides many advantages over traditional evaluation approaches that use outside consultants to provide midterm and end-of-project evaluations. The results-framework process, which spans the life of the project, provides an opportunity for program staff, donors, partners, and evaluators to work as a team to collect and use rich, longitudinal data for project planning, implementation, and evaluation purposes.     

Are game theoretic concepts suitable negotiation support tools? From Nash equilibrium refinements toward a cognitive concept of rationality

If game theory is to be used as a negotiation support tool, it should be able to provide unambiguous recommendations for a target to aim at and for actions to reach this target. This need cannot be satisfied with the Nash equilibrium concept, based on the standard instrumental concept of rationality. These equilibria, as is well known, are generally multiple in a game. The concept of substantive or instrumental rationality has proved to be so pregnant, however, that researchers, instead of re-evaluating its use in game theory, have simply tried to design concepts related to the Nash equilibrium, but with the property of being unique in a game — i.e., they have devised ways ofselecting among Nash equilibria. These concepts have been labeledrefined Nash equilibria. The purpose of this paper is to show the following.

1. The different types of refined Nash equilibria, based on the principle of backward induction, can lead to severe contradictions within the framework itself. This makes these concepts utterly unsatisfactory and calls for a new appraisal of the reasoning process of the players.
2. The degree of confidence in the principle of backward induction depends upon the evaluation of potential deviations with respect to the extended Nash equilibrium concept used and upon the possible interpretations of such deviations by the different players. Our goal is to show that the nature of these possible interpretations reinforces the argument that a serious conceptual reappraisal is necessary.
3. Some form of forward induction should then become the real yardstick of rationality, extending Simonianprocedural rationality towards the concept ofcognitive rationality. This could open the way to a renewed game theoretic approach to negotiation support systems. Such a research program, which would be a revision of the basic game theoretic concepts, is dealt with in the end of the paper.

     

Effects of long-term landscape dynamics and city growth on biodiversity in the Mediterranean: the case study of Montpellier,France

In the Mediterranean, long-term land-use changes have resulted into landscape mosaics composed of very few ancient woodland remnants scattered across extended post-agricultural woodlands. Patches of ancient woodlands are now suffering rapid urban growth that reduces their area and impact their associated biodiversity. Here we use the case study of Montpellier, one of the most dynamic cities in France, to 1) characterize temporal changes in land covers (between 1860 and 2006) in its area, and 2) using two guilds of fungal bioindicators (i.e., polypores and lichens), to compare biodiversity stakes between ancient and secondary Mediterranean woodlands. We used a combination of historical maps, archives, fungal collections and field survey in eight Quercus ilex patches (4 ancient versus 4 recent replicates) to reconstruct landscapes dynamics and assess biodiversity changes. From the 19th to the 21st century, over half (52.4%) of the ancient woodlands within Montpellier were replaced by other land covers, mainly by urban equipment, while secondary patches (16.8% of the total area) were naturally established. Remaining ancient woodlands show multi-layered vegetation made of multi-secular Pinus halepensis dominating a dynamic understorey made of Quercus ilex and various Mediterranean shrubs. Polypores, but not macrolichens, tended to differ in community composition between ancient and recent woodland patches, with the highest diversity found in ancient woodlands. This study highlights that urban woodland patches of contrasted histories harbour distinct biodiversity stakes to be included in urban planning and provide valuable areas to evaluate biodiversity patterns and dynamics.     

Empirically based conversion factors for calculating couple-years of protection

Couple-years of protection (CYP) is one of several commonly used indicators to assess international family planning efforts. It has been the subject of much debate, relating in part to the specific conversion factors used to translate the quantity of the respective contraceptive methods distributed to a single measure of protection. This article outlines a comprehensive effort to revisit those conversion factors based on the best available empirical evidence. In most instances, the analysis supports previously established standard conversion factors. However, there are two notable departures. Fewer condoms and spermicides are recommended for each CYP (120 vs. 150), primarily because coital frequency among condom users is lower than previously assumed. Furthermore, for sterilization, the authors recommend the use of country or region-specific conversion factors. Every program evaluation indicator has strengths and weaknesses, and the best program evaluation efforts use a variety of indicators. If CYP is used to evaluate programs, however, the authors believe that the conversion factors presented reflect the best available evidence.     

Compensation for What? An Analysis of Insurance Strategies for Repairable Assets

We define a repairable asset as an irreplaceable commodity whose quality is at risk, but can be partly restored at a cost. Examples are houses, automobiles and, especially, health, for which standard monetary approaches are oversimplified. To optimize the value of insurance, the insurer and the insured have to agree upon repair strategies (when to fix the asset and how much) and compensation rules (how much money to receive for other goods). We clarify the role of the consumer's preferences in the properties of the contract, and we highlight the relationship between repair strategies and the super- or submodular structure of the repair technology.