Migration as a source of growth: The perspective of a developing country

This paper analyses the dynamics of migratory flows and growth in a developing economy. We show that when workers freely choose their location, some natives can rationally decide to return to their home country after they have accumulated a certain amount of knowledge abroad, while some prefer to stay permanently in the same economy (either at home or abroad). We point out that worker mobility can have an expansionary effect on the developing economy. Moreover, we show that in the long-run, as the sending economy develops, fewer natives are likely to emigrate and more migrants are likely to return. Received: 7 December 2000/Accepted: 25 April 2001     

Pascal’s and Tabarrok’s Wagers

In a recent paper A. Tabarrok [Believe in Pascal’s Wager? Have I Got a Deal for You!, Theory and Decision 48, 123--128, 2000] argued that a believer who accepts Pascal’s Wager should in addition accept payment of any given fee in return for a given increase in the probability of reaching God. However the conclusion is obtained from manipulations of infinities which are not valid in an expected utility model. In this note, an alternative model is formulated in which Tabarrok’s conclusion can be obtained.     

Adjustment mechanisms and intergenerational actuarial neutrality in pension reforms

In the context of the reform of defined benefit pension systems under population ageing, we focus on the introduction of automatic adjustment mechanisms linked to life expectancy. Our goal is to establish a relationship between changes in the key parameters of the pension system and changes in life expectancy, applying the principle of intergenerational actuarial neutrality. For a defined benefit pension scheme, we first obtain the fundamental adjustment equation and then, for particular cases, we derive different designs of automatic adjustment mechanisms depending on the involved parameter. We include a numerical application only for illustrative purposes.     

Hormesis: A Highly Generalizable and Reproducible Phenomenon With Important Implications for Risk Assessment

From a comprehensive search of the literature, the hormesis phenomenon was found to occur over a wide range of chemicals, taxonomic groups, and endpoints. By use of computer searches and extensive cross-referencing, nearly 3000 potentially relevant articles were identified. Evidence of chemical and radiation hormesis was judged to have occurred in approximately 1000 of these by use of a priori criteria. These criteria included study design features (e.g., number of doses, dose range), dose–response relationship, statistical analysis, and reproducibility of results. Numerous biological endpoints were assessed, with growth responses the most prevalent, followed by metabolic effects, reproductive responses, longevity, and cancer. Hormetic responses were generally observed to be of limited magnitude with an average maximum stimulation of 30 to 60 percent over that of the controls. This maximum usually occurred 4- to 5-fold below the NOAEL for a particular endpoint. The present analysis suggests that hormesis is a reproducible and generalizable biological phenomenon and is a fundamental component of many, if not most, dose–response relationships. The relatively infrequent observation of hormesis in the literature is believed to be due primarily to experimental design considerations, especially with respect to the number and range of doses and endpoint selection. Because of regulatory considerations, most toxicologic studies have been carried out at high doses above the low-dose region where the hormesis phenomenon occurs.     

资源受限下平行工序顺序对优化的0-1规划模型

资源受限是工程项目时刻都可能面对的挑战。由于资源限制,需要将原项目计划中相互之间无优先关系的平行工序调整为顺序工序。平行工序顺序化可导致项目工期延迟,因此需考虑如何使项目工期延迟最小。该平行工序顺序优化问题是项目调度问题,也是排列组合问题,通常难度很大,包括一些NP-hard问题。本文主要研究该问题的一类典型子问题——平行工序顺序对优化,即如何将项目中某2n个平行工序调整为n个顺序工序对,并且对项目工期的影响最小。该问题的总方案数可达到（2n）!/n!。本文借助工序网络（如CPM网络）,运用简单的时间参数量化了平行工序顺序化对项目工期的影响,进而降低问题的求解难度,建立了纯0-1规划模型。实验验证了该模型的求解效率,求解100个平行工序规模的问题平均耗时0.2605秒,而求解500个平行工序规模的问题平均耗时10.66秒。     

Les services à la personne,toujours dévalorisés? Analyse et classification dans une optique comparative

L'auteure compare la rémunération des travailleurs des services à la personne selon le prestige de la profession exercée dans différents pays (Canada, États‐Unis, Japon, République de Corée et Taïwan (Chine)), en s'appuyant sur des microdonnées de la Luxembourg Income Study. Elle classe ces professions selon leur degré de «fermeture sociale» et analyse la pénalité ou la prime salariale qui leur est associée dans chaque pays. Elle mesure aussi empiriquement les similarités et différences entre les États‐providence «libéraux» et ceux qui sont plutôt «développeurs productivistes», ainsi qu'au sein de ces régimes, confirmant la nette convergence internationale des services à la personne sous l'effet de la mondialisation.     

ARTIFICIAL STATES

We define artificial states as those in which political borders do not coincide with a division of nationalities desired by the people on the ground. We propose and compute for most countries in the world two measures of the degree to which borders may be artificial. One measures how borders split ethnic groups into two separate adjacent countries. The other measures the straightness of land borders, under the assumption the straight land borders are more likely to be artificial. We then show that these two measures are correlated with several measures of political and economic success.     

Skewed zero-bound distributions and process capability indices for upper specifications

A common practical situation in process capability analysis, which is not well developed theoretically, is when the quality characteristic of interest has a skewed distribution with a long tail towards relatively large values and an upper specification limit only exists. In such situations, it is not uncommon that the smallest possible value of the characteristic is 0 and this is also the best value to obtain. Hence a target value 0 is assumed to exist. We investigate a new class of process capability indices for this situation. Two estimators of the proposed index are studied and the asymptotic distributions of these estimators are derived. Furthermore, we suggest a decision procedure useful when drawing conclusions about the capability at a given significance level, based on the estimated indices and their asymptotic distributions. A simulation study is also performed, assuming that the quality characteristic is Weibull-distributed, to investigate the true significance level when the sample size is finite.