Numerical Testing of a New Positivity-Preserving Interpolation Algorithm

An important component of a number of computational modeling algorithms is an interpolation method that preserves the positivity of the function being interpolated. This report describes the numerical testing of a new positivity-preserving algorithm that is designed to be used when interpolating from a solution defined on one grid to different spatial grid. The motivating application is a numerical weather prediction (NWP) code that uses spectral elements as the discretization choice for its dynamics core and Cartesian product meshes for the evaluation of its physics routines. This combination of spectral elements, which use nonuniformly spaced quadrature/collocation points, and uniformly-spaced Cartesian meshes combined with the desire to maintain positivity when moving between these necessitates our work. This new approach is evaluated against several typical algorithms in use on a range of test problems in one or more space dimensions. The results obtained show that the new method is competitive in terms of observed accuracy while at the same time preserving the underlying positivity of the functions being interpolated.Comment: 58 pages, 17 figure

Challenges and achievements in the utilization of the health system among adolescents in a region of Burkina Faso particularly affected by poverty

Objective: Healthcare for adolescents receives little attention in low-income countries globally despite their large population share in these settings, the importance of disease prevention at these ages for later life outcomes and adolescent health needs differing from those of other ages. We therefore examined healthcare need and use among adolescents in rural Burkina Faso to identify reasons for use and gaps in provision and uptake. Methods: We interviewed 1,644 adolescents aged 12-20 living in rural northwestern Burkina Faso in 2017. Topics included healthcare need and satisfaction with care provided. We calculated response-weighted prevalence of perceived healthcare need and utilization, then conducted multivariable regression to look at predictors of need, realized access and successful utilization based on the Andersen and Aday model. Results: 43.7 [41.2 - 46.0] % of participants perceived need for healthcare at least once in the preceding 12 months - 52.0 [48.1 - 56.0] % of females and 35.6 [32.5 - 39.0] % of males. Of those with perceived need, 92.6 [90.0 - 94.3] % were able to access care and 79.0 [75.6 - 82.0] % obtained successful utilization. Need was most strongly predicted by gender, education and urbanicity, while predictors of successful use included household wealth and female guardian’s educational attainment. Conclusion: Healthcare utilization among adolescents is low in rural Burkina Faso, but mostly thought of as sufficient with very few individuals reporting need that was not linked to care. Future objective assessment of healthcare need could help identify whether our results reflect a well-functioning system for these adolescents, or one where barriers lead to low awareness of needs or low expectations for service provision

Frailty and physical performance in the context of extreme poverty: a population-based study of older adults in rural Burkina Faso [version 1; peer review: 2 approved]

Background: Little is known about the prevalence of frailty and about normal values for physical performance among older individuals in low-income countries, in particular those in sub-Saharan Africa. We describe the prevalence of phenotypic frailty, and values and correlates of several physical performance measures in a cohort of middle-aged and older people living in rural Burkina Faso, one of the world’s poorest communities. Methods: We analysed data collected from participants aged over 40 in Nouna district, Burkina Faso. We measured handgrip strength, four metre walk speed, chair rise time, and derived the Fried frailty score based on grip strength, gait speed, body mass index, self-reported exhaustion, and physical activity. Frailty and physical performance indicators were then correlated with health and sociodemographic variables including comorbid disease, marital status, age, sex, wealth and activity impairment. Results: Our sample included 2973 individuals (1503 women), mean age 54 years. 1207 (43%) were categorised as non-frail, 1324 (44%) as prefrail, 212 (7%) as frail, and 167 (6%) were unable to complete all five frailty score components. Lower grip strength, longer chair stand time, lower walk speed and prevalence of frailty rose with age. Frailty was more common in women than men (8% vs 6%, p=0.01) except in those aged 80 and over. Frailty was strongly associated with impairment of activities of daily living and with lower wealth, being widowed, diabetes mellitus, hypertension, and self-reported diagnoses of tuberculosis or heart disease. With the exception of grip strength, which was higher in women than prior international normative values, women had greater deficits than men in physical performance. Conclusions: Phenotypic frailty and impaired physical performance were associated as expected with female sex, co-morbidities, increasing age and impaired activities of daily living. These results support the use of frailty measurements for classification of ageing related syndromes in this setting

Impairment in Activities of Daily Living and unmet need for care among older adults: A population-based study from Burkina Faso

OBJECTIVES: The importance of impairment in performing Activities of Daily Living (ADL) is likely to increase in sub-Saharan Africa since few care options for affected people exist. This study investigated the prevalence of ADL impairment, the extent to which care-need was met and described characteristics of people with ADL impairment and unmet need in Burkina Faso. METHODS: This study used data from the CRSN Heidelberg Aging Study, a population-based study among 3,026 adults aged over 40 years conducted in rural Burkina Faso. Information on six basic ADL items was sought, with a follow-up question asking whether care-needs were not met, partially met or met. Bivariable correlations and multivariable logistic regression were used to determine sociodemographic and health characteristics associated with ADL impairment and unmet need. RESULTS: ADL impairment of any kind was reported by 1,202 (39.7%) respondents and was associated with older age (Adjusted Odds Ratio: 1.05 [95% CI: 1.04-1.06]), being a woman (1.33 [1.06-1.60]) and reporting depressive symptoms (1.90 [1.65-2.18]). Among those with ADL impairment, 67.8% had at least one unmet need. Severe ADL impairment was found in 202 (6.7%) respondents, who reported lower prevalence of unmet need (43.1%). Severe ADL impairment was associated with depressive symptoms (2.55 [2.11-3.07]) to a stronger degree than any ADL impairment. DISCUSSION: Prevalence of ADL impairment and unmet need was high in this setting. Variation in impairment across the population highlighted key groups for future interventions. Unmet need for care was highest in middle-aged adults, indicating a gap in care provision