From a drought to HIV: An analysis of the effect of droughts on transactional sex and sexually transmitted infections in Malawi.

Each year there are over 300 natural disasters globally with millions of victims that cost economic losses near USD$100 billion. In the context of climate change, an emerging literature linking extreme weather events to HIV infections suggests that efforts to control the HIV epidemic could be under threat. We used Demographic and Health Survey (DHS) data collected during the 2015-2016 harsh drought that affected several areas of Malawi to provide new evidence on the effect of an unanticipated economic shock on sexual behaviours of young women and men. We find that amongst women employed in agriculture, a six-months drought doubles their likelihood of engaging in transactional sex compared to women who were not affected by the drought and increases their likelihood of having a sexually transmitted infections (STI) by 48% in the past twelve months. Amongst men employed outside of agriculture, drought increases by 50% the likelihood of having a relationship with a woman engaged in transactional sex. These results suggest that women in agriculture experiencing economic shocks as a result of drought use transactional sex with unaffected men, i.e. men employed outside agriculture, as a coping mechanism, exposing themselves to the risk of contracting HIV. The effect was especially observed among non-educated women. A single drought in the last five years increases HIV prevalence in Malawi by around 15% amongst men and women. Overall, the results confirm that weather shocks are important drivers of risky sexual behaviours of young women relying on agriculture in Africa. Further research is needed to investigate the most adequate formal shock-coping strategies to be implemented in order to limit the negative consequences of natural disasters on HIV acquisition and transmission.

Agriculture and forest land use change in the continental United States: Are there tipping points?

Land use in the United States (US) is driven by multiple forces operating at the global level, such as income and population growth, yield and productivity improvement, trade policy, climate change, and changing diets. Future land use has implications for biodiversity, run-off, carbon storage, ecosystem values, agriculture, and the broader economy. We investigate those forces and their implications from a multisector, multisystem dynamics (MSD) perspective focused on understanding dynamics and resilience in complex interdependent systems. Historical trends show slight increases in grassland and natural forest areas and decreases in cropland. We project these trends to intensify under higher pressures for agriculture land and reduce under lower pressures, with no evidence of tipping points toward larger agricultural land abandonment or deforestation. However, US sectoral output and trade, fertilizer use, N2O and CH4 emissions from agriculture activities, and CO2 emissions from land use changes are substantially impacted under land use forcing scenarios.

Is current irrigation sustainable in the United States? An integrated assessment of climate change impact on water resources and irrigated crop yields.

While climate change impacts on crop yields has been extensively studied, estimating the impact of water shortages on irrigated crop yields is challenging because the water resources management system is complex. To investigate this issue, we integrate a crop yield reduction module and a water resources model into the MIT Integrated Global System Modeling framework, an integrated assessment model linking a global economic model to an Earth system model. We assess the effects of climate and socioeconomic changes on water availability for irrigation in the U.S. as well as subsequent impacts on crop yields by 2050, while accounting for climate change projection uncertainty. We find that climate and socioeconomic changes will increase water shortages and strongly reduce irrigated yields for specific crops (i.e., cotton and forage), or in specific regions (i.e., the Southwest) where irrigation is not sustainable. Crop modeling studies that do not represent changes in irrigation availability can thus be misleading. Yet, since the most water-stressed basins represent a relatively small share of U.S. irrigated areas, the overall reduction in U.S. crop yields is small. The response of crop yields to climate change and water stress also suggests that some level of adaptation will be feasible, like relocating croplands to regions with sustainable irrigation or switching to less irrigation intensive crops. Finally, additional simulations show that greenhouse gas (GHG) mitigation can alleviate the effect of water stress on irrigated crop yields, enough to offset the reduced CO2 fertilization effect compared to an unconstrained GHG emission scenario.

Estimating unbiased economies of scale of HIV prevention projects: a case study of Avahan.

Governments and donors are investing considerable resources on HIV prevention in order to scale up these services rapidly. Given the current economic climate, providers of HIV prevention services increasingly need to demonstrate that these investments offer good 'value for money'. One of the primary routes to achieve efficiency is to take advantage of economies of scale (a reduction in the average cost of a health service as provision scales-up), yet empirical evidence on economies of scale is scarce. Methodologically, the estimation of economies of scale is hampered by several statistical issues preventing causal inference and thus making the estimation of economies of scale complex. In order to estimate unbiased economies of scale when scaling up HIV prevention services, we apply our analysis to one of the few HIV prevention programmes globally delivered at a large scale: the Indian Avahan initiative. We costed the project by collecting data from the 138 Avahan NGOs and the supporting partners in the first four years of its scale-up, between 2004 and 2007. We develop a parsimonious empirical model and apply a system Generalized Method of Moments (GMM) and fixed-effects Instrumental Variable (IV) estimators to estimate unbiased economies of scale. At the programme level, we find that, after controlling for the endogeneity of scale, the scale-up of Avahan has generated high economies of scale. Our findings suggest that average cost reductions per person reached are achievable when scaling-up HIV prevention in low and middle income countries.

[18F]F15599, a novel 5-HT1A receptor agonist, as a radioligand for PET neuroimaging.

PURPOSE: The serotonin-1A (5-HT(1A)) receptor is implicated in the pathophysiology of major neuropsychiatric disorders. Thus, the functional imaging of 5-HT(1A) receptors by positron emission tomography (PET) may contribute to the understanding of its role in those pathologies and their therapeutics. These receptors exist in high- and low-affinity states and it is proposed that agonists bind preferentially to the high-affinity state of the receptor and therefore could provide a measure of the functional 5-HT(1A) receptors. Since all clinical PET 5-HT(1A) radiopharmaceuticals are antagonists, it is of great interest to develop a( 18)F labelled agonist. METHODS: F15599 (3-chloro-4-fluorophenyl-(4-fluoro-4{[(5-methyl-pyrimidin-2-ylmethyl)-amino]-methyl}-piperidin-1-yl)-methanone) is a novel ligand with high affinity and selectivity for 5-HT(1A) receptors and is currently tested as an antidepressant. In pharmacological tests in rat, it exhibits preferential agonist activity at post-synaptic 5-HT(1A) receptors in cortical brain regions. Here, its nitro-precursor was synthesised and radiolabelled via a fluoronucleophilic substitution. Radiopharmacological evaluations included in vitro and ex vivo autoradiography in rat brain and PET scans on rats and cats. Results were compared with simultaneous studies using [(18)F]MPPF, a validated 5-HT(1A) antagonist radiopharmaceutical. RESULTS: The chemical and radiochemical purities of [(18)F]F15599 were >98%. In vitro [(18)F]F15599 binding was consistent with the known 5-HT(1A) receptors distribution (hippocampus, dorsal raphe nucleus, and notably cortical areas) and addition of Gpp(NH)p inhibited [(18)F]F15599 binding, consistent with a specific binding to G protein-coupled receptors. In vitro binding of [(18)F]F15599 was blocked by WAY100635 and 8-OH-DPAT, respectively, prototypical 5-HT(1A) antagonist and agonist. The ex vivo and in vivo studies demonstrated that the radiotracer readily entered the rat and the cat brain and generated few brain radioactive metabolites. Remarkably, in microPET studies, [(18)F]F15599 notably displayed a pattern of brain labelling that did not correlate with in vitro observations. Thus, in cat, the highest binding was observed in dorsal raphe and cingulate cortex with little binding in other cortical regions and none in hippocampus. In vivo binding was abolished by WAY100635, indicating specific labelling of 5-HT(1A) receptors. CONCLUSION: [(18)F]F15599 is a radiofluorinated agonist presenting interesting characteristics for probing in vitro and in vivo the high-affinity states of the 5-HT(1A) receptors. Its differential labelling of 5-HT(1A) receptors in vitro and in vivo may result from its reported preferential interaction with receptors coupled to specific G-protein subtypes.