Age-specific mortality levels off at advanced ages in many species; one explanation for this phenomenon is provided by the population heterogeneity theory. Although mortality at advanced ages can be well fit by heterogeneity models, population heterogeneity remains theoretical, lacking much direct evidence to support the existence of unobserved heterogeneity. Here, we provide direct evidence to...

Mendelian traits are considered as the lower end of the complexity spectrum of heritable phenotypes. However, more than a century after the rediscovery of Mendel's law, the global landscape of monogenic variants as well as their effects and inheritance patterns within natural populations is still not well understood. Using the yeast Saccharomyces cerevisiae, we performed a species-wide survey o...

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BACKGROUND Prevalence estimates of drug use, or of its consequences, are considered important in many contexts and may have substantial influence over public policy. However, it is rarely possible to simply count the relevant individuals, in particular when the defining characteristics might be illegal, as in the drug use case. Consequently methods are needed to estimate the size of such partly...

ACKNOWLEDGMENT This monograph is based upon papers and discussion from a technical review on the collection and interpretation of data from hidden populations The National Institute on Drug Abuse has obtained permission from the copyright holders to reproduce certain previously published material as noted in the text. Further reproduction of this copyrighted material is permitted only as part o...

BACKGROUND More than a billion people have some form of disabilities worldwide. Persons living with a disability have many needs (including physically, mentally, and socially needs). Estimating the size of disabled population is a challenge in health systems. An innovative indirect method to estimate the size of populations is network scale up (NSU) having widely used for hidden populations. Th...

BACKGROUND Hepatitis C virus (HCV) is a major cause of liver diseases worldwide. Due to its asymptomatic nature, screening is necessary for identification. Because screening of the total population is not cost effective, it is important to identify which risk factors for positivity characterize the key populations in which targeting of screening yields the highest numbers of HCV positives, and ...