Recent years have seen substantial growth in openly available satellite and other geospatial data layers, which represent a range of metrics relevant to global human population mapping at fine spatial scales. The specifications of such data differ widely and therefore the harmonisation of data layers is a prerequisite to constructing detailed and contemporary spatial datasets which accurately describe population distributions. Such datasets are vital to measure impacts of population growth, monitor change, and plan interventions. To this end the WorldPop Project has produced an open access archive of 3 and 30 arc-second resolution gridded data. Four tiled raster datasets form the basis of the archive: (i) Viewfinder Panoramas topography clipped to Global ADMinistrative area (GADM) coastlines; (ii) a matching ISO 3166 country identification grid; (iii) country area; (iv) and slope layer. Further layers include transport networks, landcover, nightlights, precipitation, travel time to major cities, and waterways. Datasets and production methodology are here described. The archive can be downloaded both from the WorldPop Dataverse Repository and the WorldPop Project website.

Multi-temporal, globally consistent, high-resolution human population datasets provide consistent and comparable population distributions in support of mapping sub-national heterogeneities in health, wealth, and resource access, and monitoring change in these over time. The production of more reliable and spatially detailed population datasets is increasingly necessary due to the importance of improving metrics at sub-national and multitemporal scales. This is in support of measurement and monitoring of UN Sustainable Development Goals and related agendas. In response to these agendas, a method has been developed to assemble and harmonise a unique, open access, archive of geospatial datasets. Datasets are provided as global, annual time series, where pertinent at the timescale of population analyses and where data is available, for use in the construction of population distribution layers. The archive includes sub-national census-based population estimates, matched to a geospatial layer denoting administrative unit boundaries, and a number of co-registered gridded geospatial factors that correlate strongly with population presence and density. Here, we describe these harmonised datasets and their limitations, along with the production workflow. Further, we demonstrate applications of the archive by producing multi-temporal gridded population outputs for Africa and using these to derive health and development metrics. The geospatial archive is available at https://doi.org/10.5258/ SOTON/WP00650.

The age group composition of populations varies substantially across continents and within countries, and is linked to levels of development, health status and poverty. The subnational variability in the shape of the population pyramid as well as the respective dependency ratio are reflective of the different levels of development of a country and are drivers for a country’s economic prospects and health burdens. Whether measured as the ratio between those of working age and those young and old who are dependent upon them, or through separate young and old-age metrics, dependency ratios are often highly heterogeneous between and within countries. Assessments of subnational dependency ratio and age structure patterns have been undertaken for specific countries and across high income regions, but to a lesser extent across the low income regions. In the framework of the WorldPop Project, through the assembly of over 100 million records across 6,389 subnational administrative units, subnational dependency ratio and high resolution gridded age/sex group datasets were produced for 87 countries in Africa and Asia.

ABSTRACT:Open access geospatial data represent a range of metrics relevant to global human population mapping at fine spatial scales. Detailed and contemporary spatial datasets that accurately describe population distributions are vital in order to measure impacts of population growth, monitor change, and plan interventions. To construct such datasets the harmonisation of geospatial data layers is a prerequisite because layer specifications differ widely.To this end the WorldPop Project is producing an open access archive of 3 and 30 arc-second (~100m and ~1km, respectively) resolution gridded data in a predominantly open source environment, using OSGEO4W utilities. Five tiled raster datasets form the basis of the archive: (i) Viewfinder Panoramas topography clipped to CIESIN national level administrative coastlines; (ii) a matching ISO 3166 country identification grid; (iii) country area; (iv) pixel area; (v) and slope layer. Further layers will include transport networks, landcover, urban extent, nightlights, climate, travel time to major cities, forest stand change, livestock densities, vegetation indices, and waterways. We here describe the base datasets and the production methodology in development. The alpha version of the archive can be downloaded both from the WorldPop Dataverse Repository and the WorldPop Project website. The improved and expanded beta version of the archive is in development for release next year, and will offer significantly improved standardisation of country boundaries, and inland water boundaries (forthcoming), to global census unit data.

Polydimethylsiloxanes (PDMS) have been extensively utilized for their ability to spread and lubricate surfaces. This ability can be mostly attributed to their low surface energy and extremely flexible backbone. This study examines their unique ability through a comparative analysis of the rates of spread of numerous commercially available oils and lubricants, including a series of methylterminated PDMS. The analysis facilitated the design and synthesis of two homologous series of PDMS, in which the terminal ends were functionalized as quaternary ammonium salts. The two new series of compounds were examined for their ability to spread both as neat liquids and as formulated blends. Additionally, these hybrid ionic oligomers were screened for biological activity against Staphylococcus aureus. All of the new oligomers exhibited antimicrobial properties in preliminary testing.