Predictors of restraint use among child occupants

Objectives: The objective of this study was to identify factors that predict restraint use and optimal restraint use among children aged 0 to 13 years.

Methods: The data set is a national sample of police-reported crashes for years 2010–2014 in which type of child restraint is recorded. The data set was supplemented with demographic census data linked by driver ZIP code, as well as a score for the state child restraint law during the year of the crash relative to best practice recommendations for protecting child occupants. Analysis used linear regression techniques.

Results: The main predictor of unrestrained child occupants was the presence of an unrestrained driver. Among restrained children, children had 1.66 (95% confidence interval, 1.27, 2.17) times higher odds of using the recommended type of restraint system if the state law at the time of the crash included requirements based on best practice recommendations.

Conclusions: Children are more likely to ride in the recommended type of child restraint when their state's child restraint law includes wording that follows best practice recommendations for child occupant protection. However, state child restraint law requirements do not influence when caregivers fail to use an occupant restraint for their child passengers.     

Sorption kinetics of atrazine and diuron in soils from southern Brazil

Sorption kinetics of atrazine and diuron was evaluated in soil samples from a typical landscape in Paraná. Samples were collected (0-20 cm) in a no-tillage area from Mamborê, PR, which has been cultivated under a crop rotation for the last six years. Six sampling points of the slope were selected to represent a wide range of soil chemical and physical properties found in this area. Radiolabeled tracers (14C-atrazine and 14C-diuron) were used and the radioactivity was detected by liquid scintillation counting (LSC). Sorption was accomplished for increasing equilibration periods (0.5, 1.5, 3, 6, 12, 24, and 48 h). Kinetics data fitted adequately well to Elovich equation, providing evidences that soil reaction occurs in two distinct stages: a fast, initial one followed by a slower one. During the fast phase, 34-42 and 71-79% of total atrazine and diuron applied were sorbed to soil samples. No important differences were found among combinations of soil and herbicide sorption during the slow phase. The unrealistic conditions under batch experiments should be overestimating sorption in the fast phase and underestimating diffusion in the slow phase. Sorption of both herbicides was positively correlated to organic carbon and clay contents of soils, but atrazine was much less sorbed than diuron, showing its higher potential to contaminate groundwater, specially in sandy, low organic carbon soils.     

Combined effects of copper and food on the midge Chironomus riparius in whole-sediment bioassays

Effects observed in whole-sediment bioassays must be seen as the joint effect of all sediment characteristics. In whole-sediment bioassays, however, adverse effects on test organisms are usually attributed to the presence of contaminants and effects of food are often ignored. The aim of this study was to analyze the response of the midge Chironomus riparius to sediment spiked with different combinations of food and copper. The responses of C. riparius to these spiked sediments were assessed in 10-day whole-sediment bioassays. Decreases in survival, dry weight, and length of C. riparius were observed with increasing copper concentrations. However, an increase in the amount of food resulted in an increase of larval dry weight and length until copper concentrations reached a critical threshold of 200 mg/kg. In addition, an increase in the amount of food resulted in a decrease of accumulated copper in the larvae. The present study demonstrated that the combination of copper and food in the sediment determines the performance of C. riparius in whole-sediment bioassays. The dependency of C. riparius on high feeding levels, which mask toxic effects, questions its suitability as a test organism for whole-sediment bioassays. Because benthic communities in polluted ecosystems are often exposed to varying levels of both food and toxicants it is concluded that the trophic state of the ecosystem may alter the ecological risk of sediment-bound toxicants to opportunistic benthic invertebrates such as C. riparius.     

Umbilical and uterine flow velocity waveforms in pregnancies complicated by major fetal anomalies

A continuous wave Doppler unit was used to obtain umbilical and uterine artery flow velocity waveforms in pregnancies complicated by a major fetal abnormality. A total of 139 examinations were performed on 32 women between 26 to 41 weeks' gestation, and the records were reviewed to determine the changes associated with fetal malformation. The systolic/diastolic (A/B) ratio was used as an index of blood flow resistance in the umbilical artery and the systolic minus diastolic divided by systolic (A–B)/A for the branches of the uterine artery. Seventeen out of 32 patients showed high systolic/diastolic ratio in waveforms taken from the umbilical artery. In 30 out of 32 patients the uterine artery waveform was normal (in two patients the results were equivocal). It appears that a fetal mechanism may determine the changes in the umbilical placental circulation resulting in an umbilical artery pattern of high flow resistance in more than half of the patients with congenital anomalies.     

Relationship of diversity and habitat area in North Pacific plastic-associated rafting communities

Plastic and other anthropogenic debris (e.g., rubber, tar) augment natural floating substrates (e.g., algal rafts, pumice) in the open ocean, allowing “islands” of substrate-associated organisms to persist in an otherwise unsuitable habitat. We examined a total of 242 debris objects collected in the eastern Pacific in 2009 and 2011 (32–39°N, 130–142°W) and the western Pacific in 2012 (19–41°N, 143–156°E). Here, we ask: (a) What taxa are associated with plastic rafts in the North Pacific? and (b) Does the number of taxa associated with plastic debris vary with the size of the debris “island?” We documented 95 rafting taxa from 11 phyla. We identified several potentially invasive plastic-associated rafting taxa, including the coral pathogen Halofolliculina spp. In concordance with classic species–area curves, the number of rafting taxa was positively correlated with the size of the raft. Our findings suggest that diversity patterns on plastic debris are compatible with the concept of island biogeography.     

A comparison of contaminant dynamics in arctic and temperate fish: A modeling approach

In order to compare the abilities of arctic and temperate fish to accumulate PCBs we conduct a metabolic analysis to determine how process rates in a mathematical fish contaminant model change with temperature. We evaluate the model by applying the original and adapted models to estimate PCB concentrations in lake trout (Salvelinus namaycush) in Trout Lake, Ontario, Canada, and in arctic char (Salvelinus alphinus) in Lake ?yangen, in the Norwegian high arctic. Modeled concentrations are, for the most part, within 50% of mean measured values and are comparable to the error associated with the fish data. In order to evaluate differences in fish bioaccumulation processes, the model is applied to hypothetical arctic and temperate systems, assuming the same contaminant input values in water and diet. The model predicts that temperate salmonids are able to biomagnify PCBs 6-60% more than arctic salmonids. For all congeners, the lower BMF(MAX) of arctic fish contribute to their lower concentrations. For congeners with log K(ow) < 6.0, the lower concentrations in arctic fish are also attributed to faster loss due to gill ventilation. Faster growth rates for temperate fish reduce the difference in bioaccumulation for congeners with log K(ow) > 7.0. These processes are controlled by the influence of lipid in the fish and their diet as well as the dependence of growth on temperature. We suggest that fish models originally calibrated for temperate systems may be directly applied to arctic lakes after accounting for the lipid content of the fish and their diet as well as water temperature.