In this paper, we take a global view at air pollution looking at cities and countries worldwide. We pay special attention at the spatial distribution of population and its relationship with the evolution of emissions. To do so, we build i) a unique and large dataset for more than 1200 (big) cities around the world, combining data on emissions of CO2 and PM2.5 with satellite data on built-up areas, population and light intensity at night at the grid-cell level for the last two decades, and ii) a large dataset for more than 190 countries with data from 1960 to 2010. At the city level, we find that denser cities show lower emissions per capita. We also find evidence for the importance of the spatial structure of the city, with polycentricity being associated with lower emissions in the largest urban areas, while monocentricity being more beneficial for smaller cities. In sum, our results suggest that the size and structure of urban areas matters when studying the density-emissions relationship. This is reinforced by results using our country-level data where we find that higher density in urban areas is associated with lower emissions per capita. All our main findings are robust to several controls and different specifications and estimation techniques, as well as different identification strategies.
Sub-Saharan Africa's hepatitis B virus (HBV) burden is primarily due to infection in infancy. However, data on chronic HBV infection prevalence and associated risk factors in children born post-HBV vaccination introduction are scarce. We estimated hepatitis B surface antigen (HBsAg) prevalence and risk factors in Senegalese children born during the HBV vaccination era. In 2018–2019, a community-based cross-sectional survey was conducted in Senegal among children born between 2004 and 2015 (ie after the three-dose HBV vaccine series was introduced (2004) but before the birth dose's introduction (2016)). HBsAg-positive children were identified using dried blood spots. A standardized questionnaire collected socioeconomic information. Data were age-sex weighted and calibrated to be representative of children living in the study area. Risk factors associated with HBsAg positivity were identified using negative binomial regression. Among 1,327 children, 17 were HBsAg-positive (prevalence = 1.23% (95% confidence interval [CI] 0.61–1.85)). Older age (adjusted incidence-rate ratio [aIRR] 1.31 per one-year increase, 95% CI 1.10–1.57), home vs healthcare facility delivery (aIRR 3.55, 95% CI 1.39–9.02), stitches (lifetime) (aIRR 4.79; 95% CI 1.84–12.39), tattoos (aIRR 8.97, 95% CI 1.01–79.11) and having an HBsAg-positive sibling with the same mother (aIRR 3.05, 95% CI 1.09–8.57) were all independently associated with HBsAg positivity. The low HBsAg prevalence highlights the success of the Senegalese HBV vaccination program. To further reduce HBV acquisition in children, high-risk groups, including pregnant women and siblings of HBsAg-positive individuals, must be screened. Vital HBV infection prevention measures include promoting delivery in healthcare facilities, and increasing awareness of prevention and control procedures.
Since the start of the oil counter-shock in June 2014, Algeria has experienced unprecedented twin deficits. The excessive monetisation of the public deficit coupled with other deep anomalies in the economy of this country acutely calls for reconsideration of its monetary policy. To this end a prior study of the long-run stability of money demand is needed. We estimate the demand for money for monetary aggregates M1 and M2, and cash in Algeria over the period 1979–2019, and study its long-run stability. We show that the transaction motive is significant for all three aggregates, especially for the demand for cash, reflecting the weight of informal economy “practices”. The elasticity of the scale variable is very close to unity for M2 and M1, and even equal to unity for cash demand (1.006). The elasticity of inflation is also significant for all three aggregates, although its level is higher in the case of cash demand (−6.474). Despite the persistence of certain financial repression mechanisms, interest rate elasticity is significant for all three aggregates, but higher for M1 and cash. The same observation is made for elasticity of the exchange rate, reflecting the effect of monetary substitution, especially for M1 and cash. Finally, our study concludes that the demand for money in terms of M1 remains stable, the same observation being confirmed for the M2 aggregate. However, the demand for fiat currency proves not to be stable. The consequences for the optimal design of monetary policy in Algeria are clearly stated.
We study physicians’ incentives to use personalised medicine techniques, replicating the physician’s trade-offs under the option of personalised medicine information. In a laboratory experiment conducted in two French Universities, prospective physicians played a real-effort game. We vary both the information structure (free access versus paid access to personalised medicine information) and the payment scheme (pay-for-performance (P4P), capitation (CAP) and fee-for-service (FFS)), implementing a within-subject design. Our results are threefold: (i) Compared to FFS and CAP, the P4P scheme strongly and positively impacts the decision to adopt personalised medicine. (ii) Although expected to dominate the other schemes, P4P is not always efficient in transforming free access to personalised medicine into higher quality of care. (iii) When it has to be paid for and after controlling for self-selection, personalised medicine is positively associated with quality, suggesting that subjects tend to make better use of information that comes at a cost. We find this effect to be stronger for males than for females prospective physicians. Quantification of our results however suggests that this positive impact is not strong enough to justify generalising the payment for personalised medicine access. Finally, we develop a theoretical model that includes in its set-up a commitment device component, which is the mechanism that we inferred from the data of the experiment. Our model replicates the principal results of the experiment, reinforcing the interpretation that the higher quality provided by subjects who bought personalised medicine can be interpreted as a commitment device effect.
Jan Hontelez and co-authors discuss the use of different types of evidence to inform HIV program integration.
This paper focuses on the new approach studying variations in city size and the impact that the Silk Road had on the structure of cities, demonstrated through the study of economic aspects of the Bukhara oasis. We use archaeological data, compare the ancient economy to modern ones, use modern economic theory and methods to understand ancient society, and use what we have learned about the ancient economy to understand modern economies better. In sum, we explore the past through the present and the latter through the former. Our main finding is the generation of models able to answer to the city-size distribution in different territories, comparing them between the past and the present. This study first revealed that, through Zipf's Law, we found similarities between modern post-Industrial Revolution and medieval economics. Secondly, we also found that in ancient times the structure of the city was linked with the local economic demand. We have demonstrated this through the study of cities along the Silk Road.
This paper documents the determinants of real oil price in the global market based on an empirical model embedding transitory and permanent shocks. We find evidence of significant differences in the propagation mechanisms of transitory versus permanent disturbances, pointing to the importance of disentangling their distinct effects. Permanent supply shocks are found to be very influential in driving oil price fluctuations.
This paper analyzes the effect of a pay-as-you-go pension system on the evolution of capital and pollution, and on the efficiency of an environmental versus health policy. In an overlapping generations model, we introduce endogenous longevity that depends on pollution and health expenditures. Global dynamics may display multiple balanced growth paths (BGPs). We show that by discouraging savings, a policy that promotes the pension system enlarges the environmental poverty trap. More surprisingly, the environmental policy has contrasting effects according to the significance of the pension system. If it has a small size, a more environmentally-friendly policy enlarges the environmental poverty trap and leads to a rise in capital over pollution at the highest stationary equilibrium. In contrast, in economies where intergenerational solidarity is well developed, capital over pollution decreases at the highest BGP. In such a case, the environmental policy does not necessarily lead to a better longevity and growth.