Comment: Why “an identified systemic model of the democracy‐peace nexus” does not persuade*

In their article in this journal, James, Solberg and Wolfson (1999) challenge our findings that two states are more likely to have peaceful relations if they are both democratic. They claim to develop a simultaneous system of two equations showing that peace and democracy foster each other, and that the effect of peace in encouraging democracy is stronger than that of democracy on peace. Their analysis, however, is flawed. Their research design employs measures of dispute and joint democracy that are inferior to those now common in the literature, and their equation for predicting peace is not properly specified. These problems distort their results. Even so, their results provide evidence of the pacific benefits of democracy. Analyses we conduct with a more completely specified model reveal stronger support for the democratic “ peace. Furthermore, a test of the effect of interstate conflict on democracy should be done at the national (or monadic) level of analysis; but James et al. perform a dyadic analysis. In a monadic test using vector autoregression, we find that disputes make no contribution to explaining the character of regimes. Even with their dyadic method, their finding that peace promotes democracy is not robust Including a crucial control variable, the ratio of militarily relevant national capabilities, that James et al. omitted, dramatically alters their findings.     

Military expenditure and unemployment in the OECD

The effect of military expenditure on employment is a matter of considerable importance. However, few of the standard economic analyses of unemployment take any explicit account of variations in military expenditure in their models. The purpose of this paper is to assess whether the prevalent neglect of this variable in labour economics is justified.

The paper briefly surveys previous estimates made of the employment effects of military expenditure. It then considers evidence from the simple dynamic reduced form regressions estimated on long historical series for the US and the UK and pooled post‐war data for 11 OECD countries. It does not suggest that the share of military expenditure is a significant influence on the unemployment rate. This implies that in analysing unemployment no special account need be taken of military expenditure and that the fear that reductions in the share of military expenditure will be associated with higher average unemployment levels is misplaced.     

Performance evaluation of a production/inventory system with periodic review and endogenous lead times

This paper considers a discrete time, single item production/inventory system with random period demands. Inventory levels are reviewed periodically and managed using a base‐stock policy. Replenishment orders are placed with the production system which is capacitated in the sense that there is a single server that sequentially processes the items one at a time with stochastic unit processing times. In this setting the variability in demand determines the arrival pattern of production orders at the queue, influencing supply lead times. In addition, the inventory behavior is impacted by the correlation between demand and lead times: a large demand size corresponds to a long lead time, depleting the inventory longer. The contribution of this paper is threefold. First, we present an exact procedure based on matrix‐analytic techniques for computing the replenishment lead time distribution given an arbitrary discrete demand distribution. Second, we numerically characterize the distribution of inventory levels, and various other performance measures such as fill rate, base‐stock levels and optimal safety stocks, taking the correlation between demand and lead times into account. Third, we develop an algorithm to fit the first two moments of the demand and service time distribution to a discrete phase‐type distribution with a minimal number of phases. This provides a practical tool to analyze the effect of demand variability, as measured by its coefficient of variation, on system performance. We also show that our model is more appropriate than some existing models of capacitated systems in discrete time. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

Waiting time analysis of the M/G/1 queue with finite retrial group

We consider an M/G/1 retrial queue with finite capacity of the retrial group. First, we obtain equations governing the dynamic of the waiting time. Then, we focus on the numerical inversion of the density function and the computation of moments. These results are used to approximate the waiting time of the M/G/1 queue with infinite retrial group for which direct analysis seems intractable. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

Interval scheduling: A survey

In interval scheduling, not only the processing times of the jobs but also their starting times are given. This article surveys the area of interval scheduling and presents proofs of results that have been known within the community for some time. We first review the complexity and approximability of different variants of interval scheduling problems. Next, we motivate the relevance of interval scheduling problems by providing an overview of applications that have appeared in literature. Finally, we focus on algorithmic results for two important variants of interval scheduling problems. In one variant we deal with nonidentical machines: instead of each machine being continuously available, there is a given interval for each machine in which it is available. In another variant, the machines are continuously available but they are ordered, and each job has a given “maximal” machine on which it can be processed. We investigate the complexity of these problems and describe algorithms for their solution. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

Conflict management in the Central African Republic: making genocide prevention work

This commentary analyses the international response to the crisis that struck the Central African Republic (CAR) in early December 2013. It examines three intertwined dimensions defining the courses of action available to policymakers dealing with pre-genocidal crises: the politics and institutional manoeuvring shaping the United Nations (UN) Security Council's decision to authorise an enforcement mission without deploying ‘blue helmets’ on the ground; the operational complexities involved in launching rapid reaction forces; and the interdependent logics between peacebuilding and atrocity prevention. The author argues that there are three ways for the UN Secretariat to ensure a more effective response to CAR-type situations: generating political will to respond swiftly to deteriorating crises leading to widespread abuses of human rights by advancing the concept of Responsibility to Protect as a core component of states' national interests; developing strategic frameworks for the deployment of multi-plural missions equipped to avert the actual or potential threat of atrocities; and developing joint early warning and scenario planning between peacebuilding and atrocity prevention agencies.     

Multidirectional scheduling scheme in resource‐constrained project schedulingproblem

In 2000, Klein showed that bidirectional scheduling schemes (bidss) outperform single‐directional scheduling schemes (e.g., forward or backward schemes). In 2010, Yoosefzadeh, et al. [J Math Model Algor 9 (2010), 357–373] showed that depending on the nature of the problems and also the type of priority rules used, schedules produced by a so‐called tridirectional scheduling scheme (trdss) yields shorter makespans when compared to forward, backward, and even bidss. Since the justification technique is applied in many of the state‐of‐the‐art algorithms nowadays, we show that the tuned version of the trdss outperforms the double justification technique. Moreover, we investigate the circumstances under which the trdss is more probable to generate schedules with shorter makespans. To this end, we introduce a new measure of resource requirements and their distributions, namely total amount of overflows. Our analytical as well as empirical investigations show that when the new measure is increased, it is more probable to obtain schedules with shorter makespans using the trdss. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 61: 44–55, 2014