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- ItemTopological data analysis of contagion maps for examining spreading processes on networks([London] : Nature Publishing Group UK, 2015) Taylor, Dane; Klimm, Florian; Harrington, Heather A.; Kramár, Miroslav; Mischaikow, Konstantin; Porter, Mason A.; Mucha, Peter J.Social and biological contagions are influenced by the spatial embeddedness of networks. Historically, many epidemics spread as a wave across part of the Earth’s surface; however, in modern contagions long-range edges—for example, due to airline transportation or communication media—allow clusters of a contagion to appear in distant locations. Here we study the spread of contagions on networks through a methodology grounded in topological data analysis and nonlinear dimension reduction. We construct ‘contagion maps’ that use multiple contagions on a network to map the nodes as a point cloud. By analysing the topology, geometry and dimensionality of manifold structure in such point clouds, we reveal insights to aid in the modelling, forecast and control of spreading processes. Our approach highlights contagion maps also as a viable tool for inferring low-dimensional structure in networks.
- ItemImpact of unseasonable flooding on women's food security and mental health in rural Sylhet, Bangladesh: a longitudinal observational study(Amsterdam : Elsevier, 2022) Gepp, Sophie; Waid, Jillian L; Brombierstäudl, Dagmar; Kader, Abdul; Müller-Hauser, Anna A; Wendt, Amanda S; Dame, Juliane; Gabrysch, SabineBackground Climate change will lead to more frequent and intensive flooding. In April, 2017, unseasonably early flooding led to the inundation of low-lying cropland before the rice harvest in northeastern Bangladesh. We describe coping strategies and quantify short-term and medium-term effects of flooding events on food security and depressive symptoms of women. Methods This observational study is part of the cluster-randomised Food and Agricultural Approaches to Reducing Malnutrition trial (FAARM; NCT02505711). Women self-reported flooding exposure on behalf of their households when surveyed (approximately 6 months after the event). Remote sensing analysis was used to detect the extent of the flooding. We collected data on household food security at baseline, depressive symptoms 4–5 months before the flooding, and coping strategies immediately after the event. We followed up on these outcome measurements for depressive symptoms and food security for up to 2·5 years after the flooding event. We used multilevel regression adjusting for intervention allocation and pre-flooding measures to quantify the flood's effect on household food security and women's mental health. Findings The FAARM trial included 2700 young women in 96 settlements in rural Sylhet, Bangladesh. 1335 (56%) of 2405 women reported that their household being greatly affected, with many losing a large part of their rice harvest. Borrowing money with interest was the most common coping strategy, with households paying back on average 1·5 times the borrowed amount. Greatly affected households had higher odds of food insecurity, with a decreasing effect with increasing time after the flood (odds ratio: 2·4 [p<0·0001] 0·5 years after; 1·6 [p<0·0001] 2·0 years after]; and 1·3 [p=0·012] 2·5 years after). Women in such households also had 1·45 times higher odds of depression (p=0·0001) 2·5 years after the flooding event. Interpretation The 2017 flooding event negatively affected food security and the mental health of women in rural Sylhet, Bangladesh, and few affected women received formal government support. To reduce the impact of future floods, livelihood adaptations and expansion of financial protection programmes are essential measures to pursue. Funding German Federal Ministry for Education and Research (Berlin, Germany) and UK Department for International Development (London, UK).