Modern thermoplastic (hot glue) versus organic-based adhesives and haft bond failure rate in experimental prehistoric ballistics

Abstract: The prehistoric production of composite technologies throughout human evolution was facilitated greatly by the use of adhesives. One such technology was projectile weaponry, which used adhesive to attach a stone point to a wooden shaft. Prehistoric projectile weaponry is often studied via experimental archaeology, which recreates ancient technologies to understand their manufacture and function. Here, we explore whether a modern thermoplastic adhesive can serve as a suitable replacement for two organic adhesives that would have been used by past peoples – pine resin and hide glue – in modern experimental tests of prehistoric weaponry. We conducted a ballistics experiment and shot groups of stone-tipped arrows, each group hafted with one of the three adhesives, and assessed the haft bond failure rate. The modern thermoplastic adhesive was similar to that of the pine resin and significantly failed less often than the hide glue. We conclude that in some cases modern thermoplastic adhesive can be substituted for organic-based adhesives in experimental archaeology. Our results also show that hafting bond failure rate was significantly different between the pine resin and the hide glue, suggesting that prehistoric hunter-gatherers faced costs or benefits in selecting adhesives for hafting

Improving access to care and community health in Haiti with optimized community health worker placement.

The national deployment of polyvalent community health workers (CHWs) is a constitutive part of the strategy initiated by the Ministry of Health to accelerate efforts towards universal health coverage in Haiti. Its implementation requires the planning of future recruitment and deployment activities for which mathematical modelling tools can provide useful support by exploring optimised placement scenarios based on access to care and population distribution. We combined existing gridded estimates of population and travel times with optimisation methods to derive theoretical CHW geographical placement scenarios including constraints on walking time and the number of people served per CHW. Four national-scale scenarios that align with total numbers of existing CHWs and that ensure that the walking time for each CHW does not exceed a predefined threshold are compared. The first scenario accounts for population distribution in rural and urban areas only, while the other three also incorporate in different ways the proximity of existing health centres. Comparing these scenarios to the current distribution, insufficient number of CHWs is systematically identified in several departments and gaps in access to health care are identified within all departments. These results highlight current suboptimal distribution of CHWs and emphasize the need to consider an optimal (re-)allocation