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In many countries of the world millions of people are not registered at birth. However, in order to assess children’s nutritional status it is necessary to have an exact knowledge of their age. In the present paper we discuss the effects of insufficient or imprecise age data on estimates of undernutrition prevalence.
Birth registration rates and levels of stunting, underweight and wasting were retrieved from Multiple Indicator Cluster Surveys and Demographic and Health Surveys of thirty-seven sub-Saharan African countries, considering the subdivision in wealth quintiles. The composition of the cross-sectional sample used for nutritional evaluation was analysed using a permutation test. Logistic regression was applied to analyse the relationship between birth registration and undernutrition. The 95 % probability intervals and Student’s t test were used to evaluate the effect of age bias and error.
Heterogeneous sampling designs were detected among countries, with different percentages of children selected for anthropometry. Further, registered children were slightly more represented within samples used for nutritional analysis than in the total sample. A negative relationship between birth registration and undernutrition was recognized, with registered children showing a better nutritional status than unregistered ones, even within each wealth quintile. The over- or underestimation of undernutrition in the case of systematic over- or underestimation of age, respectively, the latter being more probable, was quantified up to 28 %. Age imprecision was shown to slightly overestimate undernutrition.
Selection bias towards registered children and underestimation of children’s age can lead to an underestimation of the prevalence of undernutrition.
During the latest part of the Quaternary period (approximately from 11,000 to 50,000 years ago), a variety of large animals went extinct across extensive areas of the planet (Martin & Klein, 1984; MacPhee, 1999). Although a widespread phenomenon, late Quaternary extinctions of the so-called ‘megafauna’ varied greatly in intensity and timing around the world. So, while Europe, Asia, and Africa experienced only limited losses toward the end of the Pleistocene, the Americas, Australia, Madagascar and many Oceanic islands suffered dramatic extinctions. In North America, more than two-thirds of the mammals weighing more than 44 kg disappeared about 11,000 years ago (Alroy, 2001). Nearly at the same time, in South America most of the species of medium to large mammals also vanished. Australia witnessed an even more catastrophic continent-wide die-off. Some 23 of the 24 genera of Australian land vertebrates with a body mass of 45 to 1000 kilograms had died out by around 46,000 years ago (Roberts et al., 2001). The casualties of this ‘marvellous fact’, as the English naturalist Alfred Russell Wallace called it over a century ago (Wallace, 1876), bear exotic names that evoke fantastic images. Among them were fearsome claw-footed kangaroos that weighed 300 kilograms and the giant marsupial equivalents of rhinoceros and leopard in Australia. Somewhat later in North America, sabre-toothed cats, giant bisons, mammoths, mastodons, and also less well known mammals like the short-faced bear and the giant beaver went extinct. The whopping half-ton elephant birds, the heaviest birds ever known, giant lemurs and other strange beasts disappeared from the island of Madagascar within the last millennium (Burney, 1999).
The taxonomic status and relationship of Tricholoma sulphureum and the similar T. bufonium were investigated using different sets of characters. These included morphological data on fruit bodies, ecological and chorological data, and analysis of the sequence data obtained for the ITS of basidiomes of different ecological and geographic origin. Moreover, the ectomycorrhizas formed by T. bufonium on Abies alba and Quercus sp. were characterised, and anatomical features compared with those of T. sulphureum mycorrhizas on coniferous and broad-leaved host trees. Our results revealed extensive ITS variation in members of the T. sulphureum group, but this variation was not correlated with morphology, ecology, or geographical distribution. We conclude that T. bufonium cannot be maintained as an autonomous taxon and should be treated as an infraspecific variant of T. sulphureum.