On-line bin packing with restricted repacking

Semi-on-line algorithms for the bin-packing problem allow, in contrast to pure on-line algorithms, the use of certain types of additional operations for each step. Examples include repacking, reordering or lookahead before packing the items. Here we define and analyze a semi-on-line algorithm where for each step at most k items can be repacked, for some positive integer k. We prove that the upper bound for the asymptotic competitive ratio of the algorithm is a decreasing function of k, which tends to 3/2 as k goes to infinity. We also establish lower bounds for this ratio and show that the gap between upper and lower bounds is relatively small.     

Control charts for monitoring the median in non-negative asymmetric data

Statistical Methods & Applications - Control charts are commonly used for monitoring the mean of processes. However, there are practical applications in which asymmetric data are the standard....     

Macroeconomic conditions, institutional factors and demographic structure: What causes welfare caseloads?

Some of the possible determinants of changes observed in welfare caseloads are analysed in this study. The paper attempts to explain variations in welfare caseloads on the basis of four different factors: macroeconomic conditions, interactions with other income maintenance programmes, changes in the programme's parameters and changes in the demographic structure. Different models are tested by applying time series techniques. The data employed are of an administrative nature and cover the whole period that the Madrid programme has been in operation. The results show that the effects of both unemployment and institutional variables are strong and significant. Macroeconomic effects on caseloads could be offset or reinforced by changes in unemployment protection and reforms of the programme's parameters. The significant effects found for the share of lone-parent applicants also show that demographic shifts could shape the trends of welfare rolls regardless of the changes in unemployment or the implementation of institutional reforms. The authors would like to thank Juan Gabriel Rodríguez, Minoru Kunizaki, Miguel Angel Malo and three anonymous referees for their comments and suggestions. Financial and technical support from the Spanish Institute for Fiscal Studies, the Inter-ministerial Commission on Science and Technology (SEC 2001-0746) and the Social Services Department of the Madrid Government is also gratefully acknowledged. Responsible editor: Christian Dustmann.     

Predictors of satisfaction with life among second generation migrants

As a part of a comprehensive study of the psychological acculturation of Portuguese youth born in France, this paper examines the relationship between satisfaction with life and some psychosocial variables. The sample consisted of 519 Portuguese youth resident in Paris (47% were male and 53% female). The following instruments were administered to all subjects: the Satisfaction With Life Scale, the Acculturative Attitudes Scales, the Social Anxiety Scale, two brief measures of (a) loneliness and (b) locus of control as well as a background inventory. As expected no gender differences were found, but there were significant effects on satisfaction with life related to religion, participation in an association, number of Portuguese friends and ethnic identity. Expressed satisfaction with life showed significant negative correlations with perceived difficulties of adaptation, marginalization, social anxiety, and loneliness; and positive correlations with integration and locus of control. Multiple regression analysis used to determine the significant predictor variables of satisfaction with life indicated that the strongest predictors were loneliness and perceived state of health.     

Debt management in a small open economy: A theoretical and an empirical study for Belgium

This article analyzes the effects of debt management and its consequence for the control of base money in a small open economy (Belgium). The study compares the effects obtained from a small theoretical model with the results of a larger empirical model.The theoretical model focuses on the financing of government by money operation, on the bond rate, and on the international reserve of the Central Bank.The empirical model is a medium-term one, including the demand and the supply sectors of the economy and permitting simultaneous analysis of real and financial variables.The effects of an endogeneous or exogenous debt management have been studied by numerical simulation of modification in the public expenditure, the world trade, and the discount rate.     

Global risk management

Industries that deal with hazardous systems are faced with the task of managing a spectrum of risks within resource contraints. They have essentially two options that can be combined in a global risk-management strategy: insurance (loss sharing) and risk mitigation through technical and organizational measures. In this article, global risk-management strategies based on probabilistic risk analysis and its extension to include management factors are described. Some issues and solutions are illustrated through practical examples, drawn mostly from the recent research of the Industrial Engineering Risk Research Group at Stanford (the tiles of the U.S. Space Shuttle, offshore platforms, marine pipelines, and anesthesia in modern hospitals).