African-American and white inequality in the nineteenth century American South: a biological comparison

The use of height data to measure living standards is now a well-established method in economic history. By using a new source of nineteenth century Texas state prison records, the present study contrasts the heights of comparable blacks and whites between the Civil War and Reconstruction in the American South. White stature exceeded black stature. Between 1850 and 1870, black stature declined by more than 1 cm but recovered toward the end of the nineteenth century. Postbellum white stature declined by more than 1 1/2 cm over the same period yet never recovered.

Happiness is not Enough: Cognitive Judgements as Indicators of National Wellbeing

The European Social Survey, on which this issue of the journal focuses, is a 30-nation multi-funded survey series measuring attitude change. Started in 2001, it is characterised by unusually high standards of sampling and data equivalence. Its data are made available on-line with equal access to all, and have already attracted over 20,000 users. Many papers, articles and books based on the ESS have already appeared. But none has yet employed the data—whether alone or with other sources—to derive indicators of citizens’ cognitive judgements of their society. A recent EC grant is enabling the authors to fill this gap, covering topics such as trust in national institutions, tolerance, social cohesion, social trust and fear of crime. The aim is to be able to monitor changes over time in the distance between what citizens believe their society ought to be in these respects and how they actually perceive it to be.

Malaria in Pacific populations: seen but not heard?

Most Pacific Island countries are located in the tropics, where there is an abundance of mosquitoes with the potential to carry debilitating or life-threatening vector-borne diseases. This article examines three Melanesian countries in which malaria is endemic—Papua New Guinea, Solomon Islands and Vanuatu—but the threat posed by the spread of malaria gives the issues a broader significance to the Pacific region. After discussing the spatial distribution and prevalence of malaria in the Pacific, the article examines a number of health interventions through which people have sought to control malaria. Although the disease was nearly eradicated in the Pacific in the 1970s, it is no longer in retreat. The article concludes by examining why there are still grounds for cautious optimism, and the challenges that Pacific Island countries face in reducing the impact of malaria on their populations. There is a need for prompt and concerted action on malaria at the national, regional and international levels if the public health concerns arising from the disease are to be adequately addressed.     

Business visits,knowledge diffusion and productivity

We investigate whether labor mobility can be a distinct source of growth by studying the productivity impact of business visits (BVs), vis-à-vis that of other well-known drivers of productivity enhancement. Our analysis uses an unbalanced panel—covering on average 16 sectors per year in ten countries during the period 1998–2011—which combines unique and novel data on BVs sourced from the US National Business Travel Association with Organization for Economic Cooperation and Development (OECD) data on R&D and capital formation. We find that mobility through BVs is an effective mechanism to improve productivity, being about half that obtained by investing in R&D. This relevant finding invites viewing short-term mobility as a strategic mechanism and prospective policy tool to overcome productivity slowdowns and foster economic growth.     

Effects of child support and welfare policies on nonmarital teenage childbearing and motherhood

This paper is an assessment of the impact of child support enforcement and welfare policies on nonmarital teenage childbearing and motherhood. We derive four hypotheses about the effects of policies on nonmarital teenage childbearing and motherhood. We propose that teenage motherhood and school enrollment are joint decisions for teenage girls. Based on individual trajectories during ages 12–19, our analysis uses an event history model for nonmarital teenage childbearing and a dynamic model of motherhood that is jointly determined with school enrollment. We find some evidence that child support policies indirectly reduce teen motherhood by increasing the probability of school enrollment, which, in turn, reduces the probability of teen motherhood. This finding suggests that welfare offices may wish to place greater weight on outreach programs that inform more teenagers of the existence of strong child support enforcement measures. Such programs might reduce nonmarital teen motherhood further and thus reduce the need for welfare support and child support enforcement in the long run.

Uniqueness of equilibria in atomic splittable polymatroid congestion games

We study uniqueness of Nash equilibria in atomic splittable congestion games and derive a uniqueness result based on polymatroid theory: when the strategy space of every player is a bidirectional flow polymatroid, then equilibria are unique. Bidirectional flow polymatroids are introduced as a subclass of polymatroids possessing certain exchange properties. We show that important cases such as base orderable matroids can be recovered as a special case of bidirectional flow polymatroids. On the other hand we show that matroidal set systems are in some sense necessary to guarantee uniqueness of equilibria: for every atomic splittable congestion game with at least three players and non-matroidal set systems per player, there is an isomorphic game having multiple equilibria. Our results leave a gap between base orderable matroids and general matroids for which we do not know whether equilibria are unique.     

Optimization problems with color-induced budget constraints

In 1984, Gabow and Tarjan provided a very elegant and fast algorithm for the following problem: given a matroid defined on a red and blue colored ground set, determine a basis of minimum cost among those with k red elements, or decide that no such basis exists. In this paper, we investigate extensions of this problem from ordinary matroids to the more general notion of poset matroids which take precedence constraints on the ground set into account. We show that the problem on general poset matroids becomes -hard, already if the underlying partially ordered set (poset) consists of binary trees of height two. On the positive side, we present two algorithms: a pseudopolynomial one for integer polymatroids, i.e., the case where the poset consists of disjoint chains, and a polynomial algorithm for the problem to determine a minimum cost ideal of size l with k red elements, i.e., the uniform rank-l poset matroid, on series-parallel posets.     

Approximation strategy-proof mechanisms for obnoxious facility location on a line

In the facility location game on a line, there are some agents who have fixed locations on the line where an obnoxious facility will be placed. The objective is to maximize the social welfare, e.g., the sum of distances from the facility to all agents. On collecting location information, agents may misreport the locations so as to stay far away from the obnoxious facility. In this paper, strategy-proof mechanisms are designed and the approximation ratio is used to measure the performances of the strategy-proof mechanisms. Two objective functions, maximizing the sum of squares of distances (maxSOS) and maximizing the sum of distances (maxSum), have been considered. For maxSOS, a randomized 5/3-approximated strategy-proof mechanism is proposed, and the lower bound of the approximation ratio is proved to be at least 1.042. For maxSum, the lower bound of the approximation ratio of the randomized strategy-proof mechanism is proved to be 1.077. Moreover, a general model is considered that each agent may have multiple locations on the line. For the objective functions maxSum and maxSOS, both deterministic and randomized strategy-proof mechanisms are investigated, and the deterministic mechanisms are shown to be best possible.