Astrup Alston (nerverayon8)

e UK Foreign, Commonwealth and Development Office, and the Bill & Melinda Gates Foundation. Although hindrances to the sexual and reproductive health of women are expected because of COVID-19, the actual effect of the pandemic on contraceptive use and unintended pregnancy risk in women, particularly in sub-Saharan Africa, remains largely unknown. We aimed to examine population-level changes in the need for and use of contraception by women during the COVID-19 pandemic, determine if these changes differed by sociodemographic characteristics, and compare observed changes during the COVID-19 pandemic with trends in the 2 preceding years. In this study, we used four rounds of Performance Monitoring for Action (PMA) population-based survey data collected in four geographies two at the country level (Burkina Faso and Kenya) and two at the subnational level (Kinshasa, Democratic Republic of the Congo and Lagos, Nigeria). These geographies were selected for this study as they completed surveys immediately before the onset of COVID-19 and implemented a follow-up specific to COVID-19. The first round compe was an increase in the need for contraception among nulliparous women across all geographies investigated. Our findings do not support the anticipated deleterious effect of COVID-19 on access to and use of contraceptive services by women in the earliest stages of the pandemic. Although these results are largely encouraging, we warn that these trends might not be sustainable throughout prolonged economic hardship and service disruptions. Bill & Melinda Gates Foundation. For the French translation of the abstract see Supplementary Materials section. For the French translation of the abstract see Supplementary Materials section.Time-calibrated phylogenies of extant species ("extant timetrees") are widely used to estimate historical speciation and extinction rates by fitting stochastic birth-death models.1 These approaches have long been controversial, as many phylogenetic studies report zero extinction in many taxa, contradicting the high extinction rates seen in the fossil record and the fact that the majority of species ever to have existed are now extinct.2-9 To date, the causes of this discrepancy remain unresolved. Here, we provide a novel and simple explanation for these "zero-inflated" extinction estimates, based on the recent discovery that there exist many alternative "congruent" diversification scenarios that cannot be distinguished based solely on extant timetrees.10 Due to such congruencies, estimation methods tend to converge to some scenario congruent to (i.e., statistically indistinguishable from) the true diversification scenario, but not necessarily to the true diversification scenario itself. This congruent scenario may exhibit negative extinction rates, a biologically meaningless but mathematically feasible situation, in which case estimators will tend to stick to the boundary of zero extinction. Based on this explanation, we make multiple testable predictions, which we confirm using analyses of simulated trees and 121 empirical trees. In contrast to other proposed mechanisms for erroneous extinction rate estimates,5,11-14 our proposed mechanism specifically explains the zero inflation of previous extinction rate estimates in the absence of detectable model violations, even for large trees. Not only do our results likely resolve a long-standing mystery in phylogenetics, they demonstrate that model congruencies can have severe consequences in practice.Cadherins are essential adhesion proteins that regulate tissue cohesion and paracellular permeability by assembling dense adhesion plaques at cell-to-cell contacts. Adherens junctions are central to a wide range of tissue functions; identifying protein interactions that potentiate their assembly and regulation has been the focus of research for over 2 decades. Here, we present evidence for a new, unexpect