Dendrograms, heat maps and principal component analysis - the practical use of statistical methods for source apportionment of trace elements in PM10.

Dendrogram (DE), heat map (HM) and principal component analysis (PCA) methods were used in order to identify possible emission sources of As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Sb and Se in ambient PM10 collected in the surroundings of working power plants. Each statistical tool resulted in slightly different clusters. The best approximation of possible emission sources was received by the use of statistical analysis of trace-element concentrations combined with characterization of the sampling sites. In the study, PCA was indicated as the most useful statistical tool for source apportionment of trace elements in PM10. Major sources identified by PCA included: (1) coal combustion, (2) soil and road-dust resuspension, (3) the use of pesticides and (4) waste incineration.

Higher-Order Musical Temporal Structure in Bird Song.

Bird songs often display musical acoustic features such as tonal pitch selection, rhythmicity, and melodic contouring. We investigated higher-order musical temporal structure in bird song using an experimental method called "music scrambling" with human subjects. Recorded songs from a phylogenetically diverse group of 20 avian taxa were split into constituent elements ("notes" or "syllables") and recombined in original and random order. Human subjects were asked to evaluate which version sounded more "musical" on a per-species basis. Species identity and stimulus treatment were concealed from subjects, and stimulus presentation order was randomized within and between taxa. Two recordings of human music were included as a control for attentiveness. Participants varied in their assessments of individual species musicality, but overall they were significantly more likely to rate bird songs with original temporal sequence as more musical than those with randomized temporal sequence. We discuss alternative hypotheses for the origins of avian musicality, including honest signaling, perceptual bias, and arbitrary aesthetic coevolution.

Association Between the Development of Pediatric Voice Disorders and Singing in Children's Choir.

IMPORTANCE: Pediatric vocal fold pathology is important because having a healthy voice free from disorders is crucial in a child's emotional and educational development. OBJECTIVE: To determine whether there is an association between singing in a children's choir and the development of voice disorders. DESIGN, SETTING, AND PARTICIPANTS: Prospective cohort study of children (aged 8 to 14 years) singers selected from local children's choirs and nonsingers selected from local schools evaluated at Clarós Otorhinolaryngology Clinic in Barcelona, Spain, from October 2016 through April 2018. EXPOSURES: Singing for a mean time of 7.5 hours per week for 2.5 years. MAIN OUTCOMES AND MEASURES: The primary outcome of the study was the prevalence of voice disorders measured using videostroboscopy. The obtained values were analyzed statistically and used to compare the characteristics of the children and the frequency of voice disorders between the groups. RESULTS: Of 1495 enrolled children (745 male [49.8%]; median age, 9.3 years [range, 8-14 years]), 752 were singers and 743 were nonsingers. No differences in baseline characteristics were observed between the groups. Voice disorders were more frequent in the nonsinging group than in the singing group (32.4% vs 15.6%; difference, 16.8%; 95% CI, 12.3%-21.4%). Of 12 voice disorders considered in this study, all 12 were more frequent in the nonsinging group. Functional voice disorders were more frequent in the nonsinging group than in the singing group (20.2% vs 9.4%; difference, 10.8%; 95% CI, 7.2%-14.3%), as were organic voice disorders (12.2% vs 6.1%; difference, 6.1%; 95% CI, 2.6%-9.6%). CONCLUSIONS AND RELEVANCE: Voice disorders were less common among children in the cohort who sing in choirs, possibly because of voice training and the commonly observed habit of attending regular ear, nose, and throat examination. Voice disorders may be prevented in nonsinging children if the same solicitude for voice is observed.

Trace Elements Speciation of Submicron Particulate Matter (PM1) Collected in the Surroundings of Power Plants.

This study reports the concentrations of PM1 trace elements (As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Sb and Se) content in highly mobile (F1), mobile (F2), less mobile (F3) and not mobile (F4) fractions in samples that were collected in the surroundings of power plants in southern Poland. It also reports source identification by enrichment factors (EF) and a principal component analysis (PCA). There is limited availability of scientific data concerning the chemical composition of dust, including fractionation analyses of trace elements, in the surroundings of power plants. The present study offers important results in order to fill this data gap. The data collected in this study can be utilized to validate air quality models in this rapidly developing area. They are also crucial for comparisons with datasets from similar areas all over the world. Moreover, the identification of the bioavailability of selected carcinogenic and toxic elements in the future might be used as output data for potential biological and population research on risk assessment. This is important in the context of air pollution being hazardous to human health.

PM2.5 in Urban and Rural Nursery Schools in Upper Silesia, Poland: Trace Elements Analysis.

Indoor air quality (IAQ) in nursery schools is an emerging public health challenge. Particular attention should be paid to younger children, because they are more vulnerable to air pollution than older children. Among air pollutants, fine particulate matter (PM2.5) is of the greatest interest mainly due to its strong association with acute and chronic effects on children's health. In this paper, we present concentrations of PM2.5 and the composition of its trace elements at naturally ventilated nursery schools located in the area of Gliwice, Poland. The nursery schools were selected to characterize areas with different degrees of urbanization and traffic densities during the winter and spring seasons. The results indicate there is a problem with elevated concentrations of PM2.5 inside the examined classrooms. The children's exposure to trace elements was different based on localization and season. PM2.5 concentration and its trace element composition have been studied using correlation coefficients between the different trace elements, the enrichment factor (EF) and principal component analysis (PCA). PCA allowed the identification of the three components: anthropogenic and geogenic sources (37.2%), soil dust contaminated by sewage sludge dumping (18.6%) and vehicular emissions (19.5%).