Interstellar abundance determinations from fits to X-ray absorption edges often rely on the incorrect assumption that scattering is insignificant and can be ignored. We show instead that scattering contributes significantly to the attenuation of X-rays for realistic dust grain size distributions and substantially modifies the spectrum near absorption edges of elements present in grains. The dust attenuation modules used in major X-ray spectral fitting programs do not take this into account. We show that the consequences of neglecting scattering on the determination of interstellar elemental abundances are modest; however, scattering (along with uncertainties in the grain size distribution) must be taken into account when near-edge extinction fine structure is used to infer dust mineralogy. We advertise the benefits and accuracy of anomalous diffraction theory for both X-ray halo analysis and near edge absorption studies. An open source Fortran suite, General Geometry Anomalous Diffraction Theory (GGADT), is presented that calculates X-ray absorption, scattering, and differential scattering cross sections for grains of arbitrary geometry and composition.
Aim: Infant sleep behaviours, particularly night wakings, have been identified as one of the most common concerns of parents. Despite this, few empirical studies have examined how mothers distinguish between normative and problematic infant sleep behaviours. Methods: In this study, we examined infant and maternal factors associated with maternal perceptions of infant sleep problems in an internet sample of Canadian mothers with 6-to 12-month-old infants whose infants wake at least one night a week. Results: While infant sleep behaviours accounted for 24% of the variance in maternal perceptions of infant sleep problems, including additional infant and maternal factors in the model accounted for 43%. Factors significantly associated with maternal perceptions of infant sleep problems were infant sleep behaviours (i.e. frequent night wakings, difficulties initiating sleep), difficult infant temperament, poor maternal daytime functioning and poor maternal sleep quality. Contrary to expectations, infant daytime functioning was not predictive of maternal perceptions of infant sleep problems. Conclusions: Our findings support a focus on the family, rather than the infant, when assessing and treating infant sleep problems
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