Hydrologic and soil properties of mature bioretention cells in Ontario, Canada.

Bioretention systems, which mimic natural hydrology and reduce volume of stormwater runoff, are a preferred solution for meeting water balance objectives, but lack of knowledge about the long-term performance of these systems hinders their wider adoption. This study was a field survey of mature (>3 years and up to 10 years post-construction) bioretention cells across Ontario, Canada. The survey involved visual inspections, determination of soil physical parameters and soil-water interaction parameters, infiltration capacity testing and synthetic drawdown testing. Results indicate that infiltration capacity remains above the recommended minimum of 25 mm/hr, likely due to high content soils and development of soil structure due to biological factors over time. The drawdown times for three sites ranged from 5 minutes to 6 hours, much less than the maximum allowed drawdown time of 24-48 hours. Ksat (saturated hydraulic conductivity) was only moderately negatively correlated with age, and where data existed on KSat at the beginning of operation, KSat improved for six out of nine sites. Soil-water interaction properties more closely resembled loam soils than sandy soils, which may be due to the development of a soil structure over time. We recommend conducting visual inspections regularly over infiltration capacity testing for quick determination of maintenance needs.

Biochar application during reforestation alters species present and soil chemistry.

Reforestation of landscapes is being used as a method for tackling climate change through carbon sequestration and land restoration, as well as increasing biodiversity and improving the provision of ecosystem services. The success of reforestation activities can be reduced by adverse field conditions, including those that reduce germination and survival of plants. One method for improving success is biochar addition to soil, which is not only known to improve soil carbon sequestration, but is also known to improve growth, health, germination and survival of plants. In this study, biochar was applied to soil at rates of 0, 1, 3 and 6 t ha(-1) along with a direct-seed forest species mix at three sites in western Victoria, Australia. Changes in soil chemistry, including total carbon, and germination and survival of species were measured over an 18 month period. Biochar was found to significantly increase total carbon by up to 15.6% on soils low in carbon, as well as alter electrical conductivity, Colwell phosphorous and nitrate- and ammonium-nitrogen. Biochar also increased the number of species present, and stem counts of Eucalyptus species whilst decreasing stem counts of Acacia species. Biochar has the potential to positively benefit reforestation activities, but site specific and plant-soil-biochar responses require targeted research.

Does oxidative damage to DNA increase with age?

The levels of 8-oxo-2-deoxyguanosine (oxo8dG) in DNA isolated from tissues of rodents (male F344 rats, male B6D2F1 mice, male C57BL/6 mice, and female C57BL/6 mice) of various ages were measured using sodium iodide to prevent oxidative damage to DNA during DNA isolation. Oxo8dG was measured in nuclear DNA (nDNA) isolated from liver, heart, brain, kidney, skeletal muscle, and spleen and in mitochondrial DNA (mtDNA) isolated from liver. We observed a significant increase in oxo8dG levels in nDNA with age in all tissues and strains of rodents studied. The age-related increase in oxo8dG in nDNA from old mice was shown not to the result of the tissue's reduced ability to remove the oxo8dG lesion. Rather, the increase in oxo8dG levels appears to arise from an age-related increase in the sensitivity of these tissues to oxidative stress. We also observed an age-related increase in oxo8dG in mtDNA isolated from the livers of the rats and mice. Dietary restriction, which is known to retard aging and increase the lifespan of rodents, was shown to significantly reduce the age-related accumulation of oxo8dG levels in nDNA in all tissues of male B6D23F1 mice and in most tissues of male F344 rats. Our study also showed that dietary restriction prevented the age-related increase in oxo8dG levels in mtDNA isolated from the livers of both rats and mice.

The relation of serum levels of antioxidant vitamins C and E, retinol and carotenoids with pulmonary function in the general population.

Reduced pulmonary function is an important predictor of mortality in the general population, and antioxidant vitamins are thought to positively influence pulmonary function. Vitamin C, vitamin E, retinol, and carotenoids are powerful antioxidants but information about the joint relation of serum levels of these antioxidants to pulmonary function is limited. We analyzed the association of FEV(1) and FVC with serum vitamins C and E, retinol, and carotenoids (beta-cryptoxanthin, lutein/zeaxanthin, beta-carotene, and lycopene) in a cross-sectional study. The analysis was carried out in a sample of 1,616 randomly selected residents of Western New York, USA, age 35 to 79 yr and free of respiratory disease. Lung function was adjusted for height, age, sex, and race and expressed as percentage of predicted normal FEV(1) (FEV(1)%) and FVC (FVC%). Participants in the lowest quartile of each of the serum antioxidants had consistently lower FEV(1)% and FVC% than those in higher quartiles. Multiple linear regression analysis revealed significant associations of vitamin C, vitamin E, beta-cryptoxanthin, lutein/zeaxanthin, beta-carotene, and retinol with FEV(1)% when these variables were investigated individually after adjustment for other covariates (smoking status, pack-years of smoking, weight, eosinophil count, and education). When all of these antioxidant vitamins were analyzed simultaneously in a multivariate regression model, the strongest association was seen with vitamin E and beta-cryptoxanthin. Only retinol showed an independent effect on FEV(1)% after controlling for vitamin E and beta-cryptoxanthin. As for FEV(1)%, vitamin E and beta-cryptoxanthin were most strongly related to FVC% when all variables were considered in the multivariate regression model. The differences in FEV(1) associated with a reduction of one standard deviation of serum vitamin E or beta-cryptoxanthin were equivalent to the negative influence of approximately 1 to 2 yr of aging. Our findings support the hypothesis that antioxidant vitamins may play a role in respiratory health and that vitamin E and beta-cryptoxanthin appear to be stronger correlates of lung function than other antioxidant vitamins.

A nationwide, multicenter, case-control study comparing risk factors, treatment, and outcome for vancomycin-resistant and -susceptible enterococcal bacteremia.

National Nosocomial Resistance Surveillance Group participants from 22 hospitals across the United States reviewed medical records for hospitalized patients with vancomycin-resistant enterococcal (VRE) or vancomycin-susceptible enterococcal (VSE) bacteremia to identify risk factors associated with the acquisition of VRE bacteremia, describe genetic traits of VRE strains, and identify factors predictive of clinical outcome. VRE cases were matched to VSE controls within each institution. Multiple logistic regression (LR) and classification and regression tree (CART) analysis were used to probe for factors associated with VRE bacteremia and clinical outcome. A total of 150 matched-pairs of VRE cases and VSE controls were collected from 1995 to 1997. Using LR, the following were found to be highly associated with VRE bacteremia: history of AIDS, positive HIV status, or drug abuse (OR 9.58); prior exposure with parenteral vancomycin (OR 8.37); and liver transplant history (OR 6. 75). CART analysis revealed that isolation of Enterococcus faecium, prior vancomycin exposure, and serum creatinine values > or = 1.1 mg/dl were predictors of VRE bacteremia. Greater proportions of clinical failure (60% versus 40%, P < 0.001) and all-cause mortality (52% versus 27%, P < 0.001) were seen in patients with VRE versus VSE bacteremia. Results from both LR and CART indicated that patients with persisting enterococcal bacteremia, intubation at baseline, higher APACHE II scores, and VRE bacteremia were at greater risk for poor outcome.

Divergent perspectives on community convergence.

Recent experimental and theoretical studies of community development, as well as more general studies of complex systems, indicate that historical differences and intrinsic indeterminism can lead to long-term community divergence. This observation has sparked a series of new investivations of community structure in systems that developed under controlled or natural conditions.

Physicians and attorneys: a partnership on behalf of the youngest victims of family violence.

Physicians play a vital role in court proceedings involving child abuse. This article describes the legal obligation of Maryland health care providers to report suspected cases of child abuse. It also discusses various types of testimony that may be required; reasons why physicians may be reluctant to testify; and why some types of testimony may be disallowed.

Communities as assembled structures: Do rules govern pattern?

Because of its unwieldy complexity, understanding organization at the community level has been an elusive, often frustrating enterprise. This survey concentrates on the assembly process itself, and examines whether there are mechanics to community assembly that provide the foundation for a general theory of organization at the community level.