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PubMed1982

The stress of a family move as a precipitating factor in children's burn accidents.

The present study focuses on the stress of a family move as a precipitating factor in children's burn accidents in a group of 330 burned children. Data on the type of burn injury (flame versus scald) and the age and sex of the child were related to the amount and type of family stress which the child and his/her family had experienced. Children in the study sample were found to have moved at approximately three times the rate of children in the general population. It was found that children under five, who were scalded, were more likely to have moved than older children who had sustained a flame burn. A critical period at 2-5 months after the move was identified where the child seemed to be especially vulnerable to burn accidents. Possible explanations for this critical period are suggested.

Adaptation, Psychological↗
PubMedDate not supplied

Conceptual and methodological challenges in predicting the health impacts of climate change.

Describing (not to mention quantifying) the anticipated adverse health impacts of global climate change poses basic challenges to biomedical science. First and foremost, it is beset with uncertainties and complexities; it is necessarily an 'If-Then' exercise, that takes as given climatologists' estimates of the plausible range of greenhouse-induced climate change over the coming century. The health impacts of climate change would generally not occur via the familiar direct-acting mechanisms that characterise local environmentally-induced toxicology or pathophysiology; therefore they would lack the mechanistic directness-of-effect that epidemiological research methods are best equipped to study. Rather, the health impacts would occur on a larger scale, and would result predominantly from perturbations of natural biogeochemical systems that reduce Earth's capacity for life support. Therefore, scientists will need to address the assessment of impacts within an ecological framework, and with an unusually long time horizon. This assessment requires a new capacity for systems-based thinking, predictive modelling, and dealing with uncertainty. Scientists, policy-makers and general public will have to adjust to unfamiliar styles of 'anticipatory' science, with an unusual overlay of uncertainty and provisionality.

Climate↗
PubMed2006

Does Haber's law apply to human sensory irritation?

Irritation of the eyes, nose, and throat by airborne chemicals--also referred to as "sensory irritation"--is an important endpoint in both occupational and environmental toxicology. Modeling of human sensory irritation relies on knowledge of the physical chemistry of the compound(s) involved, as well as the exposure parameters (concentration and duration). A reciprocal relationship between these two exposure variables is postulated under Haber's law, implying that protracted, low-level exposures may be toxicologically equivalent to brief, high-level exposures. Although time is recognized as having an influence on sensory irritation, the quantitative predictions of Haber's Law have been addressed for only a handful of compounds in human experimental studies. We have conducted a systematic literature review that includes a semiquantitative comparison of psychophysical data extracted from controlled human exposure studies versus. the predictions of Haber's law. Studies containing relevant data involved exposures to ammonia (2), chlorine (2), formaldehyde (1), inorganic dusts such as calcium oxide (1), and the volatile organic compound 1-octene (1). With the exception of dust exposure, varying exposure concentration has a proportionally greater effect on sensory irritation than does changing exposure duration. For selected time windows, a more generalized power law model (c(n) x t = k) rather than Haber's law per se (c x t = k) yields reasonably robust predictions. Complicating this picture, however, is the frequent observation of intensity-time "plateauing," with time effects disappearing, or even reversing, after a relatively short period, depending on the test compound. The implications of these complex temporal dynamics for risk assessment and standard setting have been incompletely explored to date.

Alkenes↗
PubMed2006

Migration patterns following HIV diagnosis among adults residing in the nonurban Deep South.

Health care needs of those infected with the human immunodeficiency virus (HIV) and subsequent transmission dynamics are altered by migration after infection. We interviewed 760 HIV-infected persons attending HIV-specialty clinics living in non-urban Alabama and Mississippi to ascertain the likely geographic origins of their infections, determine their post-HIV diagnosis mobility, and identify predictors of this mobility. Most subjects (81%) were living in these two states when diagnosed and have not moved since learning of their HIV status (70%). Of those who moved their primary residence post-HIV diagnosis (25% of the entire study population), the majority in-migrated to Alabama or Mississippi from elsewhere. Persons who had moved post-HIV diagnosis were more likely to be male, an injection drug user, an urban resident at HIV diagnosis, have an AIDS-defining condition, and have moved prior to HIV diagnosis. We conclude that most HIV transmission in non-urban Alabama and Mississippi is acquired locally. These results underline the need to expand HIV prevention programs in the Deep South.

Adolescent↗
PubMed1990

Population density and cancer mortality differentials in New York State, 1978-1982.

Patterns of cancer mortality within five population density quintiles in Upstate New York (New York State, exclusive of New York City), were investigated between 1978 and 1982. Sex-specific standardized mortality ratios (SMRs) were calculated within each population density quintile for all cancer deaths combined and for site-specific cancer deaths based on cancer mortality patterns exhibited by the general population of New York State, exclusive of New York City. Areas with the highest population density demonstrated a 12% excess of cancer deaths among males and a 6% excess among females. In contrast, areas with the lowest population density exhibited lower cancer mortality, among both males (9% less) and females (7% less). Males demonstrated a significant linear relationship between increasing population density and deaths for all cancer sites combined and for cancers of the oral cavity and pharynx, oesophagus, stomach, colon, gallbladder, pancreas, lung, prostate, and kidney. Among females, a significant linear relationship was observed between increasing population density and deaths for all cancer sites combined and for deaths due to cancers of the stomach, colon, liver and breast. Deaths due to cancers of the rectum, malignant melanomas of the skin, and cervix also exhibited unusual patterns of mortality across the population density quintiles. These data are most useful in generating hypotheses for further studies to define specific aetiological factors operating within population density groupings. Population density, as measured in this investigation, may represent a surrogate measure for other factors which are related to cancer morbidity and cancer mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1996

Effect of migration and related environmental changes on serum lipid levels in southwestern Chinese men.

To determine migration-related differences in serum lipid levels and to estimate the contribution of environmental factors to these differences, the authors conducted a cross-sectional study among 1,222 residents of southwestern China in 1988 and 1989: 521 Yi farmers living in a remote rural area, 340 Yi migrants to an urban setting, and 361 Han people living in the same urban setting. Serum total and high density lipoprotein cholesterol and serum triglyceride were measured after a 14-hour fast. Information on age, cigarette smoking, alcohol consumption, and physical activity was obtained by questionnaire. Diet was assessed by use of three 24-hour diet recalls. The Yi farmers had the lowest age-adjusted serum lipid levels among the three groups, white the Yi migrants and their Han counterparts had similar lipid levels. After adjustment for age, body mass index, cigarette smoking, alcohol drinking, and dietary nutrient intake, the difference in serum lipid profile between the Yi migrants and the Yi farmers was substantially reduced. These results indicate that rural-urban migration is associated with higher serum lipid levels. This migration-related difference in serum lipids can be partially explained by changes in lifestyle and dietary nutrient intake. The authors conclude that environmental factors are important determinants of population serum lipid levels in southwestern Chinese.

Adolescent↗
PubMed2003

The effect of concurvity in generalized additive models linking mortality to ambient particulate matter.

In recent years, a number of studies have applied generalized additive models to time series data to estimate associations between exposure to air pollution and cardiorespiratory morbidity and mortality. If concurvity, the nonparametric analogue of multicollinearity, is present in the data, statistical software such as S-plus can seriously underestimate the variance of fitted model parameters, leading to significance tests with inflated type 1 error. This paper uses computer simulation and analyses of actual epidemiologic data to explore this underestimation of standard errors. We provide a method for assessing concurvity in data and an alternate class of models that is unaffected by concurvity. We argue that some degree of concurvity is likely to be present in all epidemiologic time series datasets and we explore through the use of meta-analysis the possible impact of concurvity on the existing body of work relating ambient levels of sulfate particles to mortality.

Air Pollutants↗
PubMedDate not supplied

Theoretical approaches for investigating patient safety.

Patient safety and freedom from accidental injury is an issue that is promoting the search for excellence among healthcare providers, payers, and consumers. The issue is complex and multifaceted, providing many avenues for analysis, quality enhancement, and research. Several models exist that may assist in exploring patient safety issues and the relationships between error and safety. Three models are discussed and research questions are generated that with further investigation will help us to understand the complexity of error management and the promotion of patient safety. Because of their leadership role and guardianship in managing patient care, clinical nurse specialists understand and promote models that improve safety for their patients.

Ergonomics↗
PubMed2003

Mathematical tools for planning effective intervention scenarios for sexually transmitted diseases.

BACKGROUND: We studied the dynamics of sexually transmitted diseases in structured populations, deriving analogies from the theory of metapopulations. GOAL: The goal was to study the impact of potential interventions, such as reducing the probability of transmission (e.g., by condom use), reducing the duration of infectiousness (e.g., by early diagnosis and treatment), or reducing the number of new contacts. STUDY DESIGN: A structured SIS model was used for the study. RESULTS: We extended the concept of core groups to the concept of nodal epidemiologic contribution (NEC) by considering the contribution that an individual in a particular (social, spatial, or other such) group makes to a target quantity, such as the threshold condition for disease persistence, the equilibrium prevalence, or the number of disease transmissions in the long term. The measures for NEC derived here are analogous to patch values in metapopulation theory, which measure the contributions of particular habitat patches to various-aspects of metapopulation dynamics. CONCLUSION: Our results highlight that intervention measures should be targeted especially promptly if the goal is the complete eradication of the disease, as the variance in the contributions made by the individuals is the highest for this case.

Adolescent↗
PubMed2006

Influence prediction of injury and vibration on adjacent components of spine using finite element methods.

OBJECTIVES: A three-dimensional finite element (FE) model of the lumbar spine L3-L5 segment, the ligaments of which were assumed to be nonlinear materials, was established based on the actual vertebra geometry to investigate the influence of the injury lumbar spine on its adjacent components on the condition of whole-body vibration. Several injury conditions of the spine components were assumed, such as facetectomy, nucleotomy, and removal of bony posterior elements. METHODS: The dynamic FE analyses were carried out for those FE conditions under cyclic compression loads at the frequencies of 5 and 10 Hz. Then a comparison between the dynamic results and the static results was conducted to analyze the influence of both the nucleus injury and the facet joint injury on the adjacent intervertebral discs. RESULTS AND CONCLUSIONS: The results indicate that the lumbar spine exhibits not only vertical vibration but also the flexion--extension motion during vibration. The denucleation will cause high stress and large disc bulge on the disc annulus under vibration. The facet joints of lumbar spine can limit the motion amplitude of flexion-extension and protect both the posterior regions and the posterolateral regions of disc annulus from large strain and stress during vibration. The facet joint removal will increase the stress of disc annulus by around 15% at the posterior region for the conditions of nucleotomy or no vibration. The stress of annulus circumference is higher at the posterolateral region than that of other regions of annulus circumference, and the facet joint removal may exacerbate the intervertebral disc degeneration on the condition of whole-body vibration.

Compressive Strength↗
PubMed1999

A characterization of HRV's nonlinear hidden dynamics by means of Markov models.

A study of the 24-h heart rate variability's (HRV) hidden dynamic is performed hour by hour, in order to investigate the evolution of the nonlinear structure of the underlying nervous system. A hierarchy of null hypotheses of nonlinear Markov models with increasing order n is tested against the hidden dynamic of the HRV time series. The minimum accepted Markov order supplies information about the nonlinearity of the HRV's hidden dynamic and consequently of the underlying nervous system. The Markov model with minimum order is detected for each hour of the RR time series extracted from seven 24-h electrocardiogram records of patients in different pathophysiological conditions, some including ventricular tachycardia episodes. Heart rate, pNN30, and LF/HF index plots are reported to serve as a reference for the description of the patient's cardiovascular frame during each examined hour. The minimum Markov order shows to be a promising index for quantifying the average nonlinearity of the autonomic nervous system's activity.

Aged↗
PubMed1998

Military service and migration in nineteenth-century France: some evidence from Loir-et-Cher.

"Military service in France during the nineteenth century removed many young men from their own localities for long periods. The widely accepted claim that few conscripts returned home after completing their period of service is based on little evidence. The paper examines the conscription classes of 1856 and 1891 in two cantons in the departement of Loir-et-Cher. In those cases, there was not a significant relationship between conscription and migration, nor between literacy and migration. Instead, migration of youths in their twenties was linked partly to prior experiences of migration but principally to their occupations."

Adolescent↗
PubMed2004

Habitat destruction, fragmentation, and disturbance promote invasion by habitat generalists in a multispecies metapopulation.

Species invasions are extremely common and are vastly outpacing the ability of resource agencies to address each invasion, one species at a time. Management actions that target the whole landscape or ecosystem may provide more cost-effective protection against the establishment of invasive species than a species-by-species approach. To explore what ecosystem-level actions might effectively reduce invasions, we developed a multispecies, multihabitat metapopulation model. We assume that species that successfully establish themselves outside their native range tend to be habitat generalists and that a tradeoff exists between competitive ability and habitat breadth, such that habitat specialists are competitively superior to habitat generalists. In this model, habitat destruction, fragmentation, and short-term disturbances all favor invasion by habitat generalists, despite the inferior competitive abilities of generalist species. Our model results illustrate that providing relatively undisturbed habitat and preventing further habitat degradation and fragmentation can provide a highly cost-effective defense against invasive species.

Competitive Behavior↗
PubMed1992

Diabetes mellitus in Bahrain: an overview.

Bahrain has faced a rapid transition in its socio-economic status, which resulted in great changes both in life-style and in patterns of health and disease. There has been a marked decline in infectious diseases and an increase in chronic diseases. Diabetes mellitus has become one of the most common public health problems in the country. In 1988 it was estimated that 3.4% of total deaths in Bahrain were due to diabetes. A community-based study among mothers aged 18 to 48 years showed that 8.5% of them had diabetes. The percentage was found to be higher among elderly Bahrainis (12.9%). Obesity, lack of physical activity, alteration in food habits, and change in social conditions have all played a vital role in the changing prevalence of diabetes in this country. The current programmes to manage and control diabetes are limited and ineffective. Thus measures to treat diabetes should be given a high priority in the national health policy. Training of physicians in the management of diabetes, public education, epidemiological surveys, and nutritional evaluation of local foods are among the most important measures needed to control diabetes in Bahrain.

Adolescent↗
PubMed2006

Impacts of roads and hunting on central African rainforest mammals.

Road expansion and associated increases in bunting pressure are a rapidly growing threat to African tropical wildlife. In the rainforests of southern Gabon, we compared abundances of larger (>1 kg) mammal species at varying distances from forest roads and between hunted and unhunted treatments (comparing a 130-km2 oil concession that was almost entirely protected from bunting with nearby areas outside the concession that had moderate hunting pressure). At each of 12 study sites that were evenly divided between hunted and unhunted areas, we established standardized 1-km transects at five distances (50, 300, 600, 900, and 1200 m) from an unpaved road, and then repeatedly surveyed mammals during the 2004 dry and wet seasons. Hunting had the greatest impact on duikers (Cephalophus spp.), forest buffalo (Syncerus caffer nanus), and red river hogs (Potamochoerus porcus), which declined in abundance outside the oil concession, and lesser effects on lowland gorillas (Gorilla gorilla gorilla) and carnivores. Roads depressed abundances of duikers, sitatungas (Tragelaphus spekei gratus), and forest elephants (Loxondonta africana cyclotis), with avoidance of roads being stronger outside than inside the concession. Five monkey species showed little response to roads or hunting, whereas some rodents and pangolins increased in abundance outside the concession, possibly in response to greater forest disturbance. Our findings suggest that even moderate hunting pressure can markedly alter the structure of mammal communities in central Africa. Roads had the greatest impacts on large and small ungulates, with the magnitude of road avoidance increasing with local hunting pressure.

Animals↗