An examination of the recent decline in perinatal mortality in Scotland during the 1970s showed that despite substantial changes in fertility and the demographic pattern of births, differences in the age, parity, and social class composition of the obstetric population in this decade accounted for just 7% of the overall improvement in perinatal mortality between 1970 and 1979. The general patte...

OBJECTIVE To examine whether the magnitude of improvement in the health status of a population over time is dependent on the previous health status of that population. DESIGN AND SETTING A study of infant mortality rates in Canada's 12 provinces and territories between the periods 1961-1965 and 1991-1995, and of infant mortality rates in 133 countries between 1960 and 1995. MAIN OUTCOME MEA...

OBJECTIVES Concern has been raised that the occurrence of cancer may be increased in neighbourhoods around a former manufactured gas plant in Champaign, Illinois, USA. Thus, we compared historical rates of cancer in this area to comparison communities as well as with nationally standardised rates. DESIGN Retrospective population-based community cancer assessment during 1990-2010. SETTING Ch...

The difference between the disease rates of two groups, one exposed and one not exposed to a suspected aetiological factor, is a useful measure of the risk associated with the factor. This measure is of most interest when the association is considered causal, and has been termed the attributable risk (MacMahon and Pugh, 1970). Expressed as a percentage of the total disease rate in a group (the ...

AIMS AND BACKGROUND The epidemiology of colorectal cancer in Umbria, Italy, was evaluated, and data were analyzed in the pre-screening period to better understand the etiology of the disease and to develop screening strategies. MATERIALS AND METHODS Incident data were collected by the Umbrian Population Cancer Registry and mortality data by the Nominative Regional Mortality Registry from 1994...

We carried out a case-control study to investigate risk factors for childhood pneumonia in two groups of 650 children aged under two years in the city of Fortaleza, Ceará, Brazil. The cases were children recruited at the main pediatric hospital with a radiological diagnosis of pneumonia, and controls were children of the same age group recruited from the neighbourhood of the cases. In this pape...

We investigated the variation in leaf nitrogen to phosphorus ratios of tropical tree and liana seedlings as a function of the relative growth rate, whole-plant water-use efficiency, soil water content and fertilizer addition. First, seedlings of 13 tree and liana species were grown individually in 38-l pots prepared with a homogeneous soil mixture. Second, seedlings of three tree species were g...

We present an algorithm for computing Minkowski sums among surfaces of revolution and surfaces of linear extrusion, generated by slope-monotone closed curves. The special structure of these simple surfaces allows the process of normal matching between two surfaces to be expressed as an explicit equation. Based on this insight, we also present an efficient algorithm for computing the distance be...

We show that for polytopes P1, P2, . . . , Pr ⊂ R, each having ni ≥ d + 1 vertices, the Minkowski sum P1 + P2 + · · · + Pr cannot achieve the maximum of ∏ i ni vertices if r ≥ d. This complements a recent result of Fukuda & Weibel (2006), who show that this is possible for up to d − 1 summands. The result is obtained by combining methods from discrete geometry (Gale transforms) and topological ...