Exploring multiple stressor effects with Ecopath, Ecosim, and Ecospace: Research designs, modeling techniques, and future directions.

Understanding the cumulative effects of multiple stressors is a research priority in environmental science. Ecological models are a key component of tackling this challenge because they can simulate interactions between the components of an ecosystem. Here, we ask, how has the popular modeling platform Ecopath with Ecosim (EwE) been used to model human impacts related to climate change, land and sea use, pollution, and invasive species? We conducted a literature review encompassing 166 studies covering stressors other than fishing mostly in aquatic ecosystems. The most modeled stressors were physical climate change (60 studies), species introductions (22), habitat loss (21), and eutrophication (20), using a range of modeling techniques. Despite this comprehensive coverage, we identified four gaps that must be filled to harness the potential of EwE for studying multiple stressor effects. First, only 12% of studies investigated three or more stressors, with most studies focusing on single stressors. Furthermore, many studies modeled only one of many pathways through which each stressor is known to affect ecosystems. Second, various methods have been applied to define environmental response functions representing the effects of single stressors on species groups. These functions can have a large effect on the simulated ecological changes, but best practices for deriving them are yet to emerge. Third, human dimensions of environmental change - except for fisheries - were rarely considered. Fourth, only 3% of studies used statistical research designs that allow attribution of simulated ecosystem changes to stressors' direct effects and interactions, such as factorial (computational) experiments. None made full use of the statistical possibilities that arise when simulations can be repeated many times with controlled changes to the inputs. We argue that all four gaps are feasibly filled by integrating ecological modeling with advances in other subfields of environmental science and in computational statistics.

Effect of pulse repetition rate on the perception of thermal sensation with pulsed shortwave diathermy.

BACKGROUND AND PURPOSE: Pulsed shortwave diathermy (PSWD) is a form of therapy commonly used to enhance tissue repair and reduce pain. It is normally considered to be an athermal form of treatment; however, there is some evidence to suggest that thermal effects can arise with adequate dosage. The purpose of this study was to determine the pulse repetition rate (PRR) required to generate a 'possible' and 'definite' thermal sensation when PSWD was applied to the thigh. METHOD: Thirty healthy subjects were randomly assigned to placebo or treatment groups. The treatment group was exposed to PSWD at a constant setting of pulse duration (400 microseconds) and pulse power (190 W) while the PRR was increased from 26 Hz to 400 Hz in 10 increments. Each dose was applied for a period of two minutes. At the end of each application, subjects were asked if they felt a (1) 'possible' or (2) 'definite' thermal sensation. Skin temperature was measured immediately after each application. Placebo subjects were exposed to PSWD at its lowest settings throughout the experiment (pulse power = 5 W; pulse duration = 65 microseconds and PRR = 26 Hz). RESULTS: The results showed a significant correlation (p < 0.048) between PRR at 'definite' thermal sensation and skin temperature post-treatment and PRR at 'possible' thermal sensation (p < 0.001). Mean skin temperature increased significantly as PRR was increased, from 28.69 (+/- 0.75) degrees C pre-treatment to 31.14 (+/- 1.04) degrees C post-treatment, a mean difference of 2.34 degrees C. CONCLUSIONS: These results suggest that PSWD at adequate dosages can generate thermal effects, and that there is a relationship between these thermal effects and the PRR used. These results may have significant implications for the safe use of PSWD in the clinical arena.

Effects of war trauma on Cambodian refugee adolescents' functional health and mental health status.

OBJECTIVE: To measure the effect of war trauma on the functional health and mental health status of Cambodian adolescents living in a refugee camp on the Thai-Cambodian border. METHOD: A multistage probability sample identified 1,000 households in the camp known as Site Two. Interviews were conducted in each household with randomly selected adults 18 years of age and older. All adolescents aged 12 and 13 years old, along with one parent were interviewed. One hundred eighty-two adolescents (94 girls, 88 boys) and their parents participated. Culturally sensitive instruments were used including Cambodian versions of the Child Behavior Checklist (CBCL) and the Youth Self-Report (YSR). RESULTS: Parents and adolescents reported the latter having experienced high levels of cumulative trauma, especially lack of food, water, and shelter. Mean Total Problem scores were in ranges similar to those of adolescents receiving clinical care in the United States, Netherlands, and Israel. Nearly 54% (53.8%) had Total Problem scores in the clinical range by parent report on the CBCL and 26.4% by adolescent report on the YSR. The most commonly reported symptoms were somatic complaints social withdrawal attention problems, anxiety, and depression. The dose-effect relationship between cumulative trauma and symptoms was strong for parent reporting on the CBCL; the subscales on both the YSR and CBCL for Anxious/Depressed and Attention Problems revealed dose-effect associations. Dose-effect relationships between cumulative trauma and social functioning or health status were lacking. CONCLUSION: The high levels of emotional distress in this population of Cambodian adolescents and corresponding dose-effect relationships reveal the important negative psychosocial impact of violence on Cambodian adolescents. Lack of findings related to physical health status and the presence of positive social functioning of many youths should not deter health care providers and public health officials from diagnosing and treating underlying high levels of psychological distress.

Framboesia (yaws) treated with aureomycin

Ten cases of framboesia, seven showing initial lesions and nine early framboesides were treated with Aureomycin; dosage was 25 milligrammes per kilogramme body weight per day for fourteen days. The results after a twelve month period from the commencement of treatment were as follows: (i) All cases showed complete clinical cure and there were no relapses (ii) In six cases there was a reversal of the Kahn serological test; in two there was a marked decrease of titre and the two cases which were originally seronegative remained so (AU)