Self-feedbacks determine the sustainability of human interventions in eco-social complex systems: Impacts on biodiversity and ecosystem health.

Several administrative polices have been implemented in order to reduce the negative impacts of fishing on natural ecosystems. Four eco-social models with different levels of complexity were constructed, which represent the seaweed harvest in central-northern Chile under two different regimes, Management and Exploitation Areas for Benthic Resources (MAEBRs) and Open Access Areas (OAAs). The dynamics of both regimes were analyzed using the following theoretical frameworks: (1) Loop Analysis, which allows the local stability or sustainability of the models and scenarios to be assessed; and (2) Hessian´s optimization procedure of a global fishery function (GFF) that represents each dynamics of each harvest.

Ethnic density and mortality: aboriginal population health in Taiwan.

Background: Ethnic density (the proportion of ethnic minority populations in a geographic area) has emerged as an important factor determining population health. By examining the relationship between mortality rates and the proportion of aboriginal population in Taiwan, this ecological approach highlights the pressing need to understand why aboriginal health remains relatively disadvantaged affecting the population as a whole, especially given the provision of universal health coverage.

Methods: Using combined data from various government departments in Taiwan, we first compare overall mortality rates between aboriginal people and the general population in Taiwan's 21 administrative locations during the years 2010 and 2011.

Application of loop analysis for evaluation of malaria control interventions.

Background: Despite continuous efforts and recent rapid expansion in the financing and implementation of malaria control interventions, malaria still remains one of the most devastating global health issues. Even in countries that have been successful in reducing the incidence of malaria, malaria control is becoming more challenging because of the changing epidemiology of malaria and waning community participation in control interventions. In order to improve the effectiveness of interventions and to promote community understanding of the necessity of continued control efforts, there is an urgent need to develop new methodologies that examine the mechanisms by which community-based malaria interventions could reduce local malaria incidence.

Social and land use composition determinants of health: variability in health indicators.

Previous studies have shown that a community's socioeconomic status has a significant impact on its residents' health, and that vulnerability in deprived populations expresses itself as variability in health outcomes. The current study adds to this ecological research approach the notion that underlying community vulnerabilities are also related to the physical environment and population growth of a locality. The paper explores the variability in various health indicators in 252 localities in Israel as a function of the localities' socioeconomic status, population growth, and land use composition measures.

One foot in, one foot out.

As radical health professionals, we have the triple identity of workers, of activists, and of intellectuals that creates the cauldron in which we live contradictory lives. We share the concerns of other workers for salaries, job security, health and safety at work, and work load. But like teachers and unlike most other workers we are not completely alienated from our work and have a stake in the outcomes of our labors that we are not always free to express or act on.

Ecology of vector mosquitoes in Sri Lanka--suggestions for future mosquito control in rice ecosystems.

Mosquito-borne diseases are a major public health threat in Asia. To explore effective mosquito control strategies in rice ecosystems from the ecological point of view, we carried out ecological analyses of vector mosquitoes in Sri Lanka. During the 18-month study period, 14 Anopheles, 11 Culex, 5 Aedes, 2 Mansonia, and 1 Armigeres species were collected, most of which are disease vectors for malaria, filariasis, Japanese encephalitis, or dengue in Sri Lanka and elsewhere in Asia.

Coronary heart disease (CHD)--one or several diseases? Changes in the prevalence and features of CHD.

In retrospect, mortality from coronary heart disease (CHD) in the 20th century followed an epidemic pattern: mortality rates increased dramatically from 1920 until about 1960, remained roughly constant for almost a decade, and have been decreasing since the late 1960s. CHD has traditionally been conceived of as a single disease with multifactorial causality. We suggest instead that CHD cases may comprise at least two distinct populations: those associated with hypercholesterolemia, and those associated with insulin resistance.

Blood pressure and hypertension in an American colony (Puerto Rico) and on the USA mainland compared, 1886-1930.

We compare blood pressure and hypertension between adult men on the USA mainland and in Puerto Rico born during 1886-1930 to test hypotheses about the link between cardiovascular health and large socioeconomic and political changes in society: (a) 8853 men surveyed in Puerto Rico in 1965 and (b) 1449 non-Hispanic White men surveyed on the mainland during 1971-1975. Systolic and diastolic blood pressure and hypertension were regressed separately on demographic and socioeconomic variables and cardiovascular risk factors. Mainland men not taking anti-hypertensive medication showed statistically significant improvements in systolic blood pressure and hypertension at the beginning of the century and men in Puerto Rico showed improvements in diastolic blood pressure but only during the last two quinquenniums.

Impact of deforestation and agricultural development on anopheline ecology and malaria epidemiology.

To clarify mechanisms linking deforestation, anopheline ecology, and malaria epidemiology, this study draws together 60 examples of changes in anopheline ecology and malaria incidence as a consequence of deforestation and agricultural development. The deforestation projects were classified based on subsequent land use and were reviewed in terms of their impact on anopheline density and malaria incidence. To further examine different anopheline responses to land transformation, two major ecological characteristics of 31 anopheline species were tested for their associations with changes in their densities and malaria incidence.

Whose scientific method? Scientific methods for a complex world.

Critics of the precautionary principle assail it for calling for action before science establishes unquestionably that a substance causes harm. They claim theirs is the viewpoint of the "scientific method." But the conflict is not between science and antiscience but rather between different pathways for science and technology; between a commodified science-for-profit and a gentle science for humane goals; between the sciences of the smallest parts and the sciences of dynamic wholes.

Adult male height in an American colony: Puerto Rico and the USA mainland compared, 1886-1955.

The links between adult height and socioeconomic-political marginality are controversial. We test hypotheses by comparing secular trends between two groups of USA adult male citizens born during 1886-1930: (a) 9805 men surveyed in Puerto Rico during 1965 and (b) 3064 non-Hispanic Whites surveyed on the mainland during 1971-1975. Puerto Rico provides an apt case study because it is the oldest colony in the world and was the poorest region of the USA during the 20th century.

Impact of education on knowledge, agricultural practices, and community actions for mosquito control and mosquito-borne disease prevention in rice ecosystems in Sri Lanka.

Mosquito-borne diseases are a major public health threat in Sri Lanka. A 20-week pilot education program to improve community knowledge and mosquito control with participatory and non-chemical approaches was developed, implemented, and evaluated using pre-educational and post-educational surveys in two intervention and two comparison villages. Correlates of baseline knowledge were sex, number of family members, ratio of family members with malaria history, school education level, and availability of electricity at the residence.

Community-based rice ecosystem management for suppressing vector anophelines in Sri Lanka.

Sri Lanka is one of the Asian countries most affected by mosquito-borne diseases, especially malaria. This 18-month study assessed the effectiveness of a new community-based ecosystem management programme to control mosquito vectors in the country's rice ecosystem. Farmers in a malaria-prone village were educated and motivated to engage in source reduction as well as measures to restore and maximise rice ecosystem functions.

Anthropometric variability in the USA: 1971-2002.

Aim: The study analysed variability in physical stature, weight, and body mass index (BMI) in the USA during 1971-2002.

Subjects: Subjects were non-Hispanic Blacks and Whites, 2-74 years of age from the National Health and Nutrition Examination Surveys (NHANES I-III and 1999-2002).

Methods: The coefficient of variation and the standard deviation of the logarithm of stature, weight, and BMI were used to assess anthropometric variability for groups defined by age, race, sex, income, and survey year.

Life expectancy change in perturbed communities: derivation and qualitative analysis.

Pollution, loss of habitat, and climate change are introducing dramatic perturbations to natural communities and affecting public health. Populations in perturbed communities can change dynamically, in both abundance and age structure. While analysis of the community matrix can predict changes in population abundance arising from a sustained or press perturbation, perturbations also have the potential to modify life expectancy, which adds yet another means to falsify experimental hypotheses and to monitor management interventions in natural systems.

The role of seasonality in the dynamics of deer tick populations.

In this paper, we formulate a nonlinear system of difference equations that models the three-stage life cycle of the deer tick over four seasons. We study the effect of seasonality on the stability and oscillatory behavior of the tick population by comparing analytically the seasonal model with a non-seasonal one. The analysis of the models reveals the existence of two equilibrium points.

Variability and vulnerability at the ecological level: implications for understanding the social determinants of health.

Objectives: We examined variability in disease rates to gain understanding of the complex interactions between contextual socioeconomic factors and health.

Methods: We compared mortality rates between New York and California counties in the lowest and highest quartiles of socioeconomic status (SES), assessed rate variability between counties for various outcomes, and examined correlations between outcomes' sensitivity to SES and their variability.

Results: Outcomes with mortality rates that differed most by county SES were among those whose variability across counties was high (e.

Qualitative analysis of the all-cause black-white mortality crossover.

To date, despite decades of investigations and the relative abundance of mortality data, our understanding of the phenomenon of 'mortality crossover' remains inadequate. We propose a methodology for transforming mortality data from the 'age-domain' to the 'time-domain'. We then introduce a model of selection partially offset by mobility, to simulate the dynamics of vulnerability in a population cohort that is heterogeneous in health and death.

Transient dynamics and early diagnostics in infectious disease.

To date, mathematical models of the dynamics of infectious disease have consistently focused on understanding the long-term behavior of the interacting components, where the steady state solutions are paramount. However for most acute infections, the longterm behavior of the pathogen population is of little importance to the host and population health. We introduce the notion of transient pathology, where the short-term dynamics of interaction between the immune system and pathogens is the principal focus.

The precautionary principle in environmental science.

Environmental scientists play a key role in society's responses to environmental problems, and many of the studies they perform are intended ultimately to affect policy. The precautionary principle, proposed as a new guideline in environmental decision making, has four central components: taking preventive action in the face of uncertainty; shifting the burden of proof to the proponents of an activity; exploring a wide range of alternatives to possibly harmful actions; and increasing public participation in decision making. In this paper we examine the implications of the precautionary principle for environmental scientists, whose work often involves studying highly complex, poorly understood systems, while at the same time facing conflicting pressures from those who seek to balance economic growth and environmental protection.

Let the numbers speak.

Although it is often claimed that statistical techniques are ways of letting the objective data speak for themselves, in both the contrast and correlational modes of statistical inference, all the real work is done by the a priori decisions imported into the analysis--which categories are to be used to create contrasting populations, which categories are to be measured, which categories are to be held constant while others are compared, and which is cause and which is effect? The authors explore here the problem of directionality of causation and the relationship between cause and effect, on the one hand, and dependent and independent variables, on the other. In systems of any complexity there are feedbacks--negative and positive feedbacks forming loops, embedded in larger contexts and subject to influences that can impinge on the loop at any point, such that the same pair of variables may show positive correlations in some situations and negative correlations in others.

Models for regional heartwater epidemiology in a variable environment.

A model of the epidemic dynamics of heartwater within a cattle production unit was presented by Yonow et al. (1998). Here, the model is expanded to a region consisting of several farms to study the effect of environmental variability on control strategies.

Toward an ecosocial view of health.

The changing patterns of health in the United States justify both celebration and dismay. We can celebrate declining mortality rates, increased life expectancy, and improvements in diagnostic and therapeutic technologies. But public health was caught by surprise by the return of infectious disease; the gap in health outcomes between rich and poor and between whites and blacks increases; there is a growing discrepancy between what is technically possible and the actual health status; and despite its greater expenditures on health, the United States lags behind the other developed countries in health outcomes.