Modelling the Ecological Comorbidity of Acute Respiratory Infection,Diarrhoea and Stunting among Children Under the Age of 5 Years in Somalia

The aim of this study was to assess spatial co‐occurrence of acute respiratory infections (ARI), diarrhoea and stunting among children of the age between 6 and 59 months in Somalia. Data were obtained from routine biannual nutrition surveys conducted by the Food and Agriculture Organization 2007–2010. A Bayesian hierarchical geostatistical shared component model was fitted to the residual spatial components of the three health conditions. Risk maps of the common spatial effects at 1×1 km resolution were derived. The empirical correlations of the enumeration area proportion were 0.37, 0.63 and 0.66 for ARI and stunting, diarrhoea and stunting and ARI and diarrhoea, respectively. Spatially, the posterior residual effects ranged 0.03–20.98, 0.16–6.37 and 0.08–9.66 for shared component between ARI and stunting, diarrhoea and stunting and ARI and diarrhoea, respectively. The analysis showed clearly that the spatial shared component between ARI, diarrhoea and stunting was higher in the southern part of the country. Interventions aimed at controlling and mitigating the adverse effects of these three childhood health conditions should focus on their common putative risk factors, particularly in the South in Somalia.     

Kings and Vikings: on the dynamics of competitive agglomeration

This paper proposes a theory of competitive agglomeration—a new enquiry into the origins of hierarchical structures and governments. As a motivating example we analyze the Viking age—the roughly 300 year period beginning in 800 AD—from the perspective of the economics of conflict. The Viking age is interesting because throughout the time period, the scale of conflict increased—small scale raiding behaviour eventually evolved into large scale clashes between armies. With this observation in mind, we present a theoretical model describing the incentives both the defending population and the invading population had to agglomerate into larger groups to better defend against attacks, and engage in attacks, respectively. We tentatively postulate that competitive agglomeration during the Viking era was a key impetus to state formation in Europe.     

Donor advised funds: Ethical issues on the new frontier of philanthropy

This paper analyzes critical ethical and legal issues related to the administration and use of Donor Advised Funds for charitable fundraising in American philanthropy. With the swift and profound reshaping of the philanthropic landscape caused by Donor Advised Funds, the mainstream charitable world continues to both digest how these changes affect their work and address the myriad of legal, ethical and donor/public relations issues that arise in connection with gifts to and distributions from them. This paper discusses the most relevant legal and ethical principles governing the sponsorship of, receipt from and contribution to Donor Advised Funds, sets forth the significant legal and ethical issues faced by each of these parties, and finally, puts forth recommendation for them to follow.     

Managers’ Corporate Entrepreneurial Actions and Job Satisfaction

Through the development and extension of theories and scholars’ subsequent empirical analyses of significant, theoretically grounded research questions, the knowledge about corporate entrepreneurship (CE) and its successful use continues to advance. Moreover, the literature suggests important relationships between the corporate environment, managers’ entrepreneurial behavior and successful implementation of corporate entrepreneurship actions. In an attempt to test some of those relationships, we describe an empirical study of 523 managers that examines the relationships among the antecedents to managers’ entrepreneurial behavior, a decision to implement entrepreneurial actions, and resulting job satisfaction and reinforcement practices.     

The visible hand: finger ratio (2D:4D) and competitive bidding

In an experiment using two-bidder first-price sealed bid auctions with symmetric independent private values and 400 subjects, we scan also the right hand of each subject. We study how the ratio of the length of the index and ring fingers (2D:4D) of the right hand, a measure of prenatal hormone exposure, is correlated with bidding behavior and total profits. 2D:4D has been reported to predict competitiveness in sports competition (Manning and Taylor in Evol. Hum. Behav. 22:61–69, 2001, and H?nekopp et al. in Horm. Behav. 49:545–549, 2006), risk aversion in lottery tasks (Dreber and Hoffman in Portfolio selection in utero. Stockholm School of Economics, 2007; Garbarino et al. in J. Risk Uncertain. 42:1–26, 2011), and the average profitability of high-frequency traders in financial markets (Coates et al. in Proc. Natl. Acad. Sci. 106:623–628, 2009). We do not find any significant correlation between 2D:4D on either bidding or profits. However, there might be racial differences in the correlation between 2D:4D and bidding and profits.     

Species Invasion as Catastrophe: The Case of the Brown Tree Snake

This paper develops a two-stage model for the optimal management of a potential invasive species. The arrival of an invasive species is modeled as an irreversible event with an uncertain arrival time. The model is solved in two stages, beginning with the post-invasion stage. Once the arrival occurs, the optimal path of species removal is that which minimizes the present value of damage and removal costs plus the expected present value of prevention costs. An expenditure-dependent, conditional hazard rate describing species arrival is developed based on discussions with natural resource managers. We solve for the optimal sequence of prevention expenditures, given the minimum invasion penalty as just described. For the case of the Brown Tree Snake potentially invading Hawaii, we find that pre-invasion expenditures on prevention are inverse U-shaped in the hazard rate. Efficient prevention should be approximately $2.9?million today and held constant until invasion. Once invasion occurs, optimal prevention requires $3.1?million annually and $1.6?million per year on species removal to keep the population at its steady state level, due to high search costs at very small population levels.     

Ordering the extraction of renewable resources: The case of multiple aquifers

Optimal sequencing of resource extraction is typically studied for nonrenewable resources. We provide conditions for optimal use of multiple sources of a renewable resource and characterize the resulting extraction sequence, resource scarcity values, and (single) efficiency price path for two groundwater aquifers and an abundant alternative resource. Even with one demand, the optimal sequence depends on the differential opportunity costs of the two renewables. A numerical simulation for the South O‘ahu aquifer system, which also allows for different distribution costs, illustrates the case of using the “leakier” aquifer first and then switching to simultaneous use of both resources. The welfare gain from specialization relative to independent management is $4.7 billion.     

The long-run relationship between private and public savings: An empirical note

This empirical note extends the recent work by Holmes (2006) in examining the long-run relationship between private and public savings in the U.S. over the post-World War II period. Standard Engle-Granger cointegration tests fail to reject the null hypothesis of no cointegration; however, once allowance is made for an endogenous break in the cointegrating relationship, the weak form of the Ricardian equivalence proposition is supported.     

A matrix exponential spatial specification

We introduce the matrix exponential as a way of modelling spatially dependent data. The matrix exponential spatial specification (MESS) simplifies the log-likelihood allowing a closed form solution to the problem of maximum-likelihood estimation, and greatly simplifies the Bayesian estimation of the model. The MESS can produce estimates and inferences similar to those from conventional spatial autoregressive models, but has analytical, computational, and interpretive advantages. We present maximum likelihood and Bayesian approaches to the estimation of this spatial model specification along with methods of model comparisons over different explanatory variables and spatial specifications.