Improving the forecast for biodiversity under climate change.

New biological models are incorporating the realistic processes underlying biological responses to climate change and other human-caused disturbances. However, these more realistic models require detailed information, which is lacking for most species on Earth. Current monitoring efforts mainly document changes in biodiversity, rather than collecting the mechanistic data needed to predict future changes. We describe and prioritize the biological information needed to inform more realistic projections of species' responses to climate change. We also highlight how trait-based approaches and adaptive modeling can leverage sparse data to make broader predictions. We outline a global effort to collect the data necessary to better understand, anticipate, and reduce the damaging effects of climate change on biodiversity.

What limits the evolutionary emergence of pathogens?

The ability of a pathogen to cause an epidemic when introduced in a new host population often relies on its ability to adapt to this new environment. Here, we give a brief overview of recent theoretical and empirical studies of such evolutionary emergence of pathogens. We discuss the effects of several ecological and genetic factors that may affect the likelihood of emergence: migration, life history of the infectious agent, host heterogeneity, and the rate and effects of mutations. We contrast different modelling approaches and indicate how details in the way we model each step of a life cycle can have important consequences on the predicted probability of evolutionary emergence. These different theoretical perspectives yield important insights into optimal surveillance and intervention strategies, which should aim for a reduction in the emergence (and re-emergence) of infectious diseases.

Effects of species diversity on disease risk.

The transmission of infectious diseases is an inherently ecological process involving interactions among at least two, and often many, species. Not surprisingly, then, the species diversity of ecological communities can potentially affect the prevalence of infectious diseases. Although a number of studies have now identified effects of diversity on disease prevalence, the mechanisms underlying these effects remain unclear in many cases. Starting with simple epidemiological models, we describe a suite of mechanisms through which diversity could increase or decrease disease risk, and illustrate the potential applicability of these mechanisms for both vector-borne and non-vector-borne diseases, and for both specialist and generalist pathogens. We review examples of how these mechanisms may operate in specific disease systems. Because the effects of diversity on multi-host disease systems have been the subject of much recent research and controversy, we describe several recent efforts to delineate under what general conditions host diversity should increase or decrease disease prevalence, and illustrate these with examples. Both models and literature reviews suggest that high host diversity is more likely to decrease than increase disease risk. Reduced disease risk with increasing host diversity is especially likely when pathogen transmission is frequency-dependent, and when pathogen transmission is greater within species than between species, particularly when the most competent hosts are also relatively abundant and widespread. We conclude by identifying focal areas for future research, including (1) describing patterns of change in disease risk with changing diversity; (2) identifying the mechanisms responsible for observed changes in risk; (3) clarifying additional mechanisms in a wider range of epidemiological models; and (4) experimentally manipulating disease systems to assess the impact of proposed mechanisms.

Oral health, sociodemographic factors, dietary and oral hygiene practices in Jordanian children.

OBJECTIVES: To investigate the association between oral health, in terms of dental caries and gingivitis, and sociodemographic factors, dental plaque, oral hygiene behaviours, infant feeding and dietary practices in 4-5-year-old Jordanian children. METHODS: Two-stage random sampling procedure was used to select children enrolled in kindergartens in Amman, Jordan. Clinical examinations were carried out by one examiner. Mothers completed questionnaires relating to sociodemographic factors, oral hygiene behaviours, infant feeding and dietary practices of the children. RESULTS: About 67% of the children had caries, 31% had dmft greater than 4 and 66% had gingivitis. Of the children who had been wholly breast-fed, 86% had been fed on demand. Mothers of children attending kindergartens with the lowest tuition fees were more likely to have breast-fed their children on demand and for more than 18 months (prolonged breast feeding) compared to those attending kindergartens with higher fees. Savory snacks were consumed by 82%, confectionery by 76% and teas with sugar by 42% of the children. Multivariate analysis showed age, dental plaque, sleeping beside the mother, use of comforters and selected dietary habits to have an independent effect on caries prevalence. Dental plaque and prolonged breast feeding exerted an independent effect on caries severity and gingivitis. The strongest association with gingivitis was dental plaque. CONCLUSIONS: In Jordan as elsewhere health promotion strategies need to be targeted to mothers from less advantaged backgrounds. Messages about infant breast feeding should emphasise that the method is beneficial to the oral health of the children if appropriately used.

The phenomenology of niche evolution via quantitative traits in a 'black-hole' sink.

Previous studies of adaptive evolution in sink habitats (in which isolated populations of a species cannot persist deterministically) have highlighted the importance of demographic constraints in slowing such evolution, and of immigration in facilitating adaptation. These studies have relied upon either single-locus models or deterministic quantitative genetic formulations. We use individual-based simulations to examine adaptive evolution in a 'black-hole' sink environment where fitness is governed by a polygenic character. The simulations track both the number of individuals and their multi-locus genotypes, and incorporate, in a natural manner, both demographic and genetic stochastic processes. In agreement with previous studies, our findings reveal the central parts played by demographic constraints and immigration in adaptation within a sink (adaptation is more difficult in environments with low absolute fitness, and higher immigration can accelerate adaptation). A novel finding is that there is a 'punctuational' pattern in adaptive evolution in sink environments. Populations typically stay maladapted for a long time, and then rapidly shift into a relatively adapted state, in which persistence no longer depends upon recurrent immigration.

Caries prevalence and patterns and their relationship to social class, infant feeding and oral hygiene in 4-5-year-old children in Amman, Jordan.

OBJECTIVES: To investigate the relationship between social class, infant feeding, oral hygiene, and prevalence and patterns of caries in 4-5-year-old Jordanian children. METHOD: Two-stage random sampling procedure was used to select children enrolled in kindergartens in Amman, Jordan. Clinical examinations were carried out by one examiner. Mothers completed questionnaires relating to social class, infant feeding and the oral hygiene habits of the children. RESULTS: Sixty-seven per cent of the children had caries; 30% had the more extensive pattern involving molars and incisors. When the significant variables were taken into account, age, social class, sleeping with the mother, use of comforter and confectionery at bed/night time were shown to be independent risk factors for caries experience. Bottle-feeding at nap/bed/night time was associated with caries in incisors and caries in incisors and/or canines. Never being breast-fed, being breast-fed for more than 18 months, being breast-fed at nap/bed/night time showed a negative association with caries confined to molars although this showed a positive association with the more extensive pattern of the disease. CONCLUSIONS: Education for mothers about appropriate breast and bottle-feeding practices should be considered in health promotion strategies.

Evaluating web-based learning modules during an MSc programme in dental public health: a case study.

The introduction of web-based learning in dentistry has raised important educational questions about the efficacy of different teaching approaches. However, studies to date have drawn conclusions that appear conflicting, or at the least, ambiguous. In this paper, it will be argued that an over-simplistic view of education and an inappropriate use of methodology have both contributed to this confusion. These points will be illustrated through the use of a case study of web-based learning in dental public health.

Food and drink consumption, sociodemographic factors and dental caries in 4-5-year-old children in Amman, Jordan.

OBJECTIVE: To investigate the association between type of food and drink consumption, sociodemographic factors and prevalence and severity of caries in 4-5-year-old Jordanian children. METHOD: Two-stage random sampling procedure was used to select children enrolled in kindergartens in Amman. Clinical examinations were carried out by one examiner. Mothers completed a questionnaire relating to sociodemographic factors and food and drink consumption. RESULTS: Snack foods were consumed by a high percentage of children. Amongst the most popular 'high in NME sugar snacks', confectionery was reported to be regularly consumed by 76% and biscuits and cakes by 71% of them. More than 50% had carbonated drinks. Children from a lower social class, attending a kindergarten with lower tuition fees had more dessert, squashes and more teas with sugar. When all variables were considered, consumption of confectionery was independently associated with caries prevalence and consumption of teas with sugar was independently associated with caries severity. CONCLUSION: The types of foods and drinks consumed as snacks by young Jordanian children were similar to those of Western countries. In the absence of more widespread oral health promotion measures and in the presence of high prevalence and severity of caries,the oral health of Jordanian children is a matter of concern.

Caries in preschool children in Amman, Jordan and the relationship to socio-demographic factors.

OBJECTIVE: To determine the prevalence and severity of caries in children attending kindergartens in Amman and the relationship between caries experience and socio-demographic factors including age, social class based on the father's occupation, the level of mother's education and the fee level of the kindergarten attended. DESIGN: Cross sectional survey including a dental examination of the child and a questionnaire completed by the parents. SETTING: Kindergarten schools in Amman. PARTICIPANTS: 1,140 children including 569 4-year-olds and 571 5-year-olds. RESULTS: Prevalence of caries in 4 year olds was 62% and in 5 year olds it was 73%. The dmft values were 3.1 and 4.1 in 4 and 5 year olds respectively. Lower caries prevalence was recorded for children of families where the father had a non-manual occupation, those whose mothers had higher levels of educational attainment and for children attending kindergartens with higher tuition fees. CONCLUSION: Caries prevalence and severity in children attending kindergarten schools in Amman are similar to those seen in studies of children of the same age in Saudi Arabia and higher than those in children in westernised countries such as the UK. As in other countries, caries experience in young children in Amman is clearly related to social factors. Findings illustrate the need for effective oral health promotion accessible to all social groups in this middle eastern capital. Fee scale of the schools appears to be an effective measure to use in designing appropriate strategies.

Oral cleanliness, gingivitis, dental caries and oral health behaviours in Jordanian children.

The aims of the study were to investigate the association between oral cleanliness, gingivitis and sociodemographic factors, dental caries and oral health behaviours amongst 4-5-year-old Jordanian children. A two stage random sampling procedure was used to select children enrolled in kindergartens in Amman. Clinical examinations were carried out by one examiner. Mothers completed questionnaires relating to sociodemographic factors and oral health behaviours. Presence of gingivitis and of four or more sites with dental plaque were seen in 66% and 83% of the children, respectively. No differences in these outcomes were seen between ages and genders. Social class and oral hygiene behaviours were important risk indicators for the level of oral cleanliness and presence of gingivitis. Higher percentages of children with four or more sites with plaque and with gingivitis had a dmft score equal or greater than four. Due to the high level of dental plaque accumulation, presence of gingivitis and their association with social class, dental caries and oral hygiene behaviours, attention should be given to the oral health of these children. In particular to the oral health of children attending kindergartens in areas of lower social class in Amman.

Dynamical mechanism for coexistence of dispersing species.

Dispersal of organisms may play an essential role in the coexistence of species. Recent studies of the evolution of dispersal in temporally varying environments suggest that clones differing in dispersal rates can coexist indefinitely. In this work, we explore the mechanism permitting such coexistence for a model of dispersal in a patchy environment, where temporal heterogeneity arises from endogenous chaotic dynamics. We show that coexistence arises from an extreme type of intermittent behavior, namely the phenomenon known as on-off intermittency. In effect, coexistence arises because of an alternation between synchronized and de-synchronized dynamical behaviors. Our analysis of the dynamical mechanism for on-off intermittency lends strong credence to the proposition that chaotic synchronism may be a general feature of species coexistence, where competing species differ only in dispersal rate.

Advances in dental public health.

Dental public health has been defined as 'the science and art of preventing oral diseases, promoting oral health and improving the quality of life through the organised efforts of society'. Dental practitioners most often have the oral health of individual patients as their primary focus but the aim of public health is to benefit populations. Early developments in dental public health were concerned largely with demonstrating levels of disease and with treatment services. With greater appreciation of the nature of oral health and disease, and of their determinants has come recognition of the need for wider public health action if the effects of prevention and oral health promotion are to be maximized.

Dynamical mechanism for coexistence of dispersing species without trade-offs in spatially extended ecological systems.

Most prior studies on the role of dispersal in the coexistence of competing species have emphasized the need for trade-offs between competitive and colonizing abilities for coexistence. Theoretical studies of the evolution of dispersal recently have revealed an alternative mechanism for the coexistence of species differing solely in dispersal rates in spatially extended systems. We present an analysis and numerical evidence indicating that chaotic synchronism, occurring in an extremely intermittent form, is an important feature of the spatiotemporal variation in fitness required for the coexistence of species without trade-offs.

Dental treatment under general anaesthesia at a hospital in Jeddah, Saudi Arabia.

UNLABELLED: Dental General Anaesthesia (DGA) has been shown to be of value in providing both restorative treatment and extractions in children who are unable to accept this using other methods of management. AIMS: The aims of this retrospective study were to determine the characteristics of patients attending for treatment under DGA at a centre in Saudi Arabia, to describe the type of dental treatment carried out using DGA and in the subsequent 3-year period. SAMPLE AND METHOD: Data were collected from hospital records of 555 patients who received treatment under DGA at King Fahad Hospital in Jeddah, Saudi Arabia, between 1995 and 1997. RESULTS: Ninety three percent of the patients were aged 8 or younger at the time of DGA, with 43% being under 5 years of age. The main indications for use of DGA in the youngest age group were dental management of rampant caries (77% of the youngest age group) and inability to accept treatment under local anaesthesia (49% of those aged 5-8 years). Seventy percent of patients had treatment involving both extractions and restorative care, and the majority, 81%, had one tooth or more restored with preformed metal crowns. Sixty-three percent of patients attended for recall after 6 months but only 10% did so after a 3-year interval. Only one of the 555 patients received a second DGA at the same centre during the 3 years following treatment. CONCLUSIONS: The service studied provides dental treatment primarily for children with extensive disease. Failure to attend for recall was common, suggesting that preventive methods which rely on regular attendance may not be successful in this group of children.

Investigation of an index to measure tooth wear in primary teeth.

UNLABELLED: Tooth wear, in particular erosion, has been reported to be widespread in children in the UK. Wear may affect either dentition, but epidemiological measurement has proved difficult. OBJECTIVES: The objectives of this study were: (a) to investigate use of a simple index of wear in primary teeth; and (b) to compare findings from visual examination and from photographs with those at histological examination of the same teeth. SAMPLE AND METHODS: Forty-one exfoliated or extracted primary anterior teeth were assessed visually and using photographs. Ground sections of the teeth were prepared and examined using polarised light microscopy. RESULTS: On visual examination, 31 of the 41 teeth had evidence of wear. In 14 teeth, tissue loss was confined to enamel and in 17 it extended into dentine. Findings on photographs were very similar to those on visual examination. Of the 10 teeth without erosion visually, two had evidence of loss on histological examination. Of the 14 with visual evidence of erosion confined to enamel, dentine was exposed in 11 cases. Diffuse demineralisation was evident histologically in 11 of the 31 teeth with evidence of erosion. CONCLUSIONS: It was concluded that clinical assessment of erosion may underestimate the extent of the condition. Under the conditions of the study, photographs gave results similar to those on visual examination.