Omar S. Ahmad

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BACKGROUND Observational studies have demonstrated an association between decreased vitamin D level and risk of multiple sclerosis (MS); however, it remains unclear whether this relationship is causal. We undertook a Mendelian randomization (MR) study to evaluate whether genetically lowered vitamin D level influences the risk of MS. METHODS AND FINDINGS(More)
International migration beyond gravity: a statistical model for use in population projections.2008. Three allometric relations of population density to body mass: Theoretical integration and empirical tests in 149 food webs. 2008. Colour of environmental noise affects the nonlinear dynamics of cycling, stage-structured populations. 2008. and environmental(More)
Stochasticity alters the nonlinear dynamics of inherently cycling populations. The power spectrum can describe and explain the impacts of stochasticity. We fitted models to short observed time series of flour beetle populations in the frequency domain, then used a well fitting stochastic mechanistic model to generate detailed predictions of population(More)
In observational studies, type-2 diabetes (T2D) is associated with an increased risk of coronary heart disease (CHD), yet interventional trials have shown no clear effect of glucose-lowering on CHD. Confounding may have therefore influenced these observational estimates. Here we use Mendelian randomization to obtain unconfounded estimates of the influence(More)
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