FESTIval: A versatile framework for conducting experimental evaluations of spatial indices.

The use of a spatial index is a common strategy to improve the performance of spatial queries in spatial database systems and Geographic Information Systems. Choosing the right spatial index to be employed in a given context requires a quantitative method to analyze the performance of spatial indices. This is done through extensive experimental evaluations. However, conducting these evaluations is an expensive, error-prone, and challenging task because (i) spatial objects are complex data to manage, (ii) spatial indices can apply different parameter values and thus assume distinct configurations, and (iii) there are indices specifically developed for different storage systems, such as disks and flash memories. In this article, we propose FESTIval, a versatile framework for conducting experimental evaluations of spatial indices. FESTIval has the following main advantages: •the support for different types of disk-based and flash-aware spatial indices;•the specification and execution of user-defined workloads;•the use of a data schema that stores index configurations and statistical data of executed workloads. Because of its characteristics, FESTIval allows users to reproduce executed experiments. Further, FESTIval provides an extensible environment, where any spatial dataset can be handled by spatial indices. FESTIval has been used to validate new proposals of flash-aware spatial indices, such as eFIND-based indices.

A multi-modal relative spatial access assessment approach to measure spatial accessibility to primary care providers.

Two-step floating catchment area (2SFCA) methods that account for multiple transportation modes provide more realistic accessibility representation than single-mode methods. However, the use of the impedance coefficient in an impedance function (e.g., Gaussian function) introduces uncertainty to 2SFCA results. This paper proposes an enhancement to the multi-modal 2SFCA methods through incorporating the concept of a spatial access ratio (SPAR) for spatial access measurement. SPAR is the ratio of a given place's access score to the mean of all access scores in the study area. An empirical study on spatial access to primary care physicians (PCPs) in the city of Albuquerque, NM, USA was conducted to evaluate the effectiveness of SPAR in addressing uncertainty introduced by the choice of the impedance coefficient in the classic Gaussian impedance function. We used ESRI StreetMap Premium and General Transit Specification Feed (GTFS) data to calculate the travel time to PCPs by car and bus. We first generated two spatial access scores-using different catchment sizes for car and bus, respectively-for each demanding population location: an accessibility score for car drivers and an accessibility score for bus riders. We then computed three corresponding spatial access ratios of the above scores for each population location. Sensitivity analysis results suggest that the spatial access scores vary significantly when using different impedance coefficients (p < 0.05); while SPAR remains stable (p = 1). Results from this paper suggest that a spatial access ratio can significantly reduce impedance coefficient-related uncertainties in multi-modal 2SFCA methods.

Does public transportation improve the accessibility of primary dental care in São Paulo, Brazil?

OBJECTIVE: Advances in geospatial technologies have recognized the role of geographic distance as a barrier to healthcare accessibility. Frequent transportation is supposed to buffer issues with distance, while infrequent services impede the uptake of care. The role of public transportation on the accessibility of health care-including oral health care-is not well elucidated in the context of megacities, such as the municipality of São Paulo, Brazil. This study aimed to compare the supply of public transportation to primary dental clinics and the population between advantaged and disadvantaged areas in São Paulo city. METHODS: A total of 4101 primary dental clinics in São Paulo city were identified and geocoded. Geographic coordinates were also retrieved for the 19 242 bus stops, 56 commuter rail stations and 64 rapid transit stations. Clinic locations and transport points were integrated with the city's 19 128 constituent census tracts-each containing sociodemographic data on the 11 252 204 residents-using Geographic Information Systems (GIS). RESULTS: Almost all clinics were located within 0.5 km of public transportation. Half of all clinics were within 0.5 km of high-frequency transport points, and three-quarters were within 1 km. Likewise, 99% of the population resided within 0.5 km of any public transportation. However, only 22% were within 0.5 km of high-frequency options, and half were within 1 km. Those within 0.5 km of high-frequency points had higher average monthly household incomes and lower illiteracy rates, with lower proportions of children and ethnic minorities, and higher proportions of older people. CONCLUSION: Clinics and populations in sociodemographically disadvantaged tracts have poorer public transportation links in São Paulo city.

The equity of access to primary dental care in São Paulo, Brazil: A geospatial analysis.

OBJECTIVES: Brazil is one of the largest countries in the world, in terms of geography and population. Most Brazilians reside in the south and south-eastern regions, with notable numbers in the regions' megacities, such as São Paulo city. Healthcare provision in such a complex environment is difficult. Thus, a clear understanding of the distribution - or rather, the maldistribution - of these services is fundamental for optimising the allocation of human and financial resources to areas of greatest privation. The present study aimed to determine the distribution of primary dental clinics in São Paulo city. METHODS: A total of 4,101 primary dental clinics in São Paulo city were identified and geocoded. Clinic locations were integrated with the city's 19,128 constituent census tracts - each containing sociodemographic data for the 11,252,204 residents - using Geographic Information Systems (GIS). RESULTS: Approximately two-thirds (64.8%) of the population resided within 0.5 km of a primary dental clinic, and a further 23.9% were within 1 km. Populations more than 1 km out were typically characterised as sociodemographically disadvantaged. Primary dental clinics were also more sparsely distributed in the city's peripheral census tracts than central census tracts. CONCLUSION: Primary dental clinics are maldistributed in São Paulo city, with disadvantaged populations having less spatial access than their advantaged counterparts.