Many dusty disks speckled clusters less than 1 million years old, but Lada saw precious few of them in a 3-million-year-old cluster and none at an age of 5 million years.
From the observed amount of beryllium (just one beryllium atom for every trillion hydrogen atoms), the team determined that some 200 million to 300 million years must have elapsed between the death of the first generation of stars in the Milky Way and the birth of the stars in the 13.4-billion-year-old cluster.
With a prevalence estimate of blindness in children of 8 per 10 000 children 0 15 years old, each cluster was expected to have approximately 24 27 blind children (144 162 in all 6 clusters).
A total of 410 students between 10 and 17 years old were cluster sampled from the primary and secondary school level.
We used population estimates from MOH and included 24 households with at least one child less than 6 years old in each cluster.
Briefly, this study was conducted in 32 rural and 34 urban clusters, including 2 urban homeless clusters; selected using a stratified random method to represent the adult population of Guntur district and systematic sampling was done to select households in order to get 200 230 eligible persons 15 49 years old in each cluster.
A sample size of 52500 adults (≧15 years old), in 35 clusters, was calculated based on detecting a change of 20% in prevalence rate of TB smear positive cases compared with the rate of the 2000 survey (95 per 100,000), with a probability greater than 95%and95%5% power, accounting for 90% response rate of participants [ 9].
In December 2004, at the time of the second survey, 7,000 LLIHs were individually distributed to all residents (≥10 years old) in the intervention clusters, obtaining a 70% coverage of the intervention population.
Exeter and Boyle's study, which was limited to young adult suicides (15 to 44 years old), found high risk clusters in Glasgow, Scotland, across three time periods with relative risks ranging from 1.53 to 2.41, while our study revealed clusters with relative risks ranging from 1.24 to 1.38.
Vaccine coverage was assessed in 1 to <2 years olds using the cluster survey technique recommended by WHO [ 15].
