The quality of some approximation formulas in a continuous review inventory model

Statistical Methods

Copper transformation, speciation, and detoxification in anoxic and suboxic freshwater sediments

The complex chemistry of copper (Cu) in freshwater sediments at low concentrations is not well understood. We evaluated the transformation processes of Cu added to freshwater sediments under suboxic and anoxic conditions. Freshwater sediments from three sources in Michigan with different characteristics (Spring Creek, River Raisin, and Maple Lake) were spiked with 30 or 60 mg kg-1 Cu and incubated under a nitrogen atmosphere. After 28-d, each treatment subset was amended with organic matter (OM) to promote anoxic conditions and evaluate its effects on Cu speciation. OM addition triggered a shift from suboxic to anoxic conditions, and sequential extractions showed that Cu accordingly shifted from acid-soluble to oxidizable fractions. Extended X-ray absorption fine-structure (EXAFS) spectroscopy revealed that Cu sulfides dominated all anoxic samples except for Spring Creek 30 mg kgxfffd; 1, where Cu(I) was predominantly complexed to thiol groups of OM. Covellite and chalcopyrite (CuFeS2) were the predominant Cu species in nearly all anoxic samples, as determined by Raman spectroscopy, scanning electron microscopy, and X-ray absorption near-edge structure (XANES) spectroscopy. Copper reduction also occurred under suboxic conditions: for two of three sediments, around 80% had been reduced to Cu(I), while the remaining 20% persisted as Cu(II) complexed to OM. However, in the third coarsest (i.e., Spring Creek), around 50% of the Cu had been reduced, forming Cu(I)-OM complexes, while the remainder was Cu(II)-OM complexes. Toxicity tests showed that survival of H. azteca and D. magna were significantly lower in suboxic treatments. Anoxic sediments triggered a near-complete transformation of Cu to sulfide minerals, reducing its toxicity

Macroevolution of desiccation‐related morphology in plethodontid salamanders as inferred from a novel surface area to volume ratio estimation approach

Evolutionary biologists have long been interested in the macroevolutionary consequences of various selection pressures, yet physiological responses to selection across deep time are not well understood. In this paper, we investigate how a physiologically-relevant morphological trait, surface area to volume ratio (SA:V) of lungless salamanders, has evolved across broad regional and climatic variation. SA:V directly impacts an organisms’ ability to retain water, leading to the expectation that smaller SA:Vs would be advantageous in arid, water-limited environments. To explore the macroevolutionary patterns of SA:V, we first develop an accurate method for estimating SA:V from linear measurements. Next, we investigate the macroevolutionary patterns of SA:V across 257 salamander species, revealing that higher SA:Vs phylogenetically correlate with warmer, wetter climates. We also observe higher SA:V disparity and rate of evolution in tropical species, mirrored by higher climatic disparity in available and occupied tropical habitats. Taken together, these results suggest that the tropics have provided a wider range of warmer, wetter climates for salamanders to exploit, thereby relaxing desiccation pressures on SA:V. Overall, this paper provides an accurate, efficient method for quantifying salamander SA:V, allowing us to demonstrate the power of physiological selection pressures in influencing the macroevolution of morphology

Cognitive Performance and Exposure to Organophosphate Flame Retardants in Children: Evidence from a Cross-Sectional Analysis of Two European Mother–Child Cohorts

The knowledge of the effects of organophosphate flame retardants on children’s neurodevelopment is limited. The purpose of the present research is to evaluate the association between exposure to organophosphate flame retardants and children’s neurodevelopment in two European cohorts involved in the Human Biomonitoring Initiative Aligned Studies. The participants were school-aged children belonging to the Odense Child Cohort (Denmark) and the PCB cohort (Slovakia). In each cohort, the children’s neurodevelopment was assessed through the Full-Scale Intelligence Quotient score of the Wechsler Intelligence Scale for Children, using two different editions. The children’s urine samples, collected at one point in time, were analyzed for several metabolites of organophosphate flame retardants. The association between neurodevelopment and each organophosphate flame retardant metabolite was explored by applying separate multiple linear regressions based on the approach of MM-estimation in each cohort. In the Danish cohort, the mean ± standard deviation for the neurodevelopment score was 98 ± 12; the geometric mean (95% confidence interval (95% CI)) of bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) standardized by creatinine (crt) was 0.52 μg/g crt (95% CI = 0.49; 0.60), while that of diphenyl phosphate (DPHP) standardized by crt was 1.44 μg/g crt (95% CI = 1.31; 1.58). The neurodevelopment score showed a small, negative, statistically imprecise trend with BDCIPP standardized by crt (β = −1.30; 95%CI = −2.72; 0.11; p-value = 0.07) and no clear association with DPHP standardized by crt (β = −0.98; 95%CI = −2.96; 0.99; p-value = 0.33). The neurodevelopment score showed a negative trend with BDCIPP (β = −1.42; 95% CI = −2.70; −0.06; p-value = 0.04) and no clear association with DPHP (β = −1.09; 95% CI = −2.87; 0.68; p-value = 0.23). In the Slovakian cohort, the mean ± standard deviation for the neurodevelopment score was 81 ± 15; the geometric mean of BDCIPP standardized by crt was 0.18 μg/g crt (95% CI = 0.16; 0.20), while that of DPHP standardized by crt was 2.24 μg/g crt (95% CI = 2.00; 3.52). The association of the neurodevelopment score with BDCIPP standardized by crt was −0.49 (95%CI = −1.85; 0.87; p-value = 0.48), and with DPHP standardized by crt it was −0.35 (95%CI = −1.90; 1.20; p-value = 0.66). No clear associations were observed between the neurodevelopment score and BDCIPP/DPHP concentrations that were not standardized by crt. No clear associations were observed with bis(1-chloro-2-propyl) phosphate (BCIPP) in either cohort, due to the low detection frequency of this compound. In conclusion, this study provides only limited evidence of an inverse association between neurodevelopment and exposure to BDCIPP and DPHP. The timing of exposure and effect modification of other organophosphate flame retardant metabolites and other substances should be the subject of further investigations that address this scientific hypothesis

Validity and reliability of the multidimensional health locus of control scale for college students

<p>Abstract</p> <p>Background</p> <p>The purpose of the present study was to assess the validity and reliability of Form A of Multidimensional Health Locus of Control scales in Iran. Health locus of control is one of the most widely measured parameters of health belief for the planning of health education programs.</p> <p>Methods</p> <p>496 university students participated in this study. The reliability coefficients were calculated in three different methods: test-retest, parallel forms and Cronbach alpha. In order to survey validity of the scale we used three methods including content validity, concurrent validity and construct validity.</p> <p>Results</p> <p>We established the content validity of the Persian translation by translating (and then back-translating) each item from the English version into the Persian version. The concurrent validity of the questionnaire, as measured by Levenson's IPC scale was .57 (P < .001), .49 (P < .01) and .53 (P < .001) for IPC, respectively. Exploratory principal components analysis supported a three-factor structure that items loading adequately on each factor. Moreover, the approximate orthogonal of the dimensions were obtained through correlation analyses. In addition, the reliability results were acceptable, too.</p> <p>Conclusion</p> <p>The results showed that the reliability and validity of Persian Form A of MHLC was acceptable and respectable and is suggested as an applicable criterion for similar studies in Iran.</p

A walk in the PARC:developing and implementing 21st century chemical risk assessment in Europe

Current approaches for the assessment of environmental and human health risks due to exposure to chemical substances have served their purpose reasonably well. Nevertheless, the systems in place for different uses of chemicals are faced with various challenges, ranging from a growing number of chemicals to changes in the types of chemicals and materials produced. This has triggered global awareness of the need for a paradigm shift, which in turn has led to the publication of new concepts for chemical risk assessment and explorations of how to translate these concepts into pragmatic approaches. As a result, next-generation risk assessment (NGRA) is generally seen as the way forward. However, incorporating new scientific insights and innovative approaches into hazard and exposure assessments in such a way that regulatory needs are adequately met has appeared to be challenging. The European Partnership for the Assessment of Risks from Chemicals (PARC) has been designed to address various challenges associated with innovating chemical risk assessment. Its overall goal is to consolidate and strengthen the European research and innovation capacity for chemical risk assessment to protect human health and the environment. With around 200 participating organisations from all over Europe, including three European agencies, and a total budget of over 400 million euro, PARC is one of the largest projects of its kind. It has a duration of seven years and is coordinated by ANSES, the French Agency for Food, Environmental and Occupational Health & Safety

Explanatory factors for first and second-generation non-western women’s inadequate prenatal care utilisation: a prospective cohort study

Background Little research into non-western women’s prenatal care utilisation in industrialised western countries has taken generational differences into account. In this study we examined non-western women’s prenatal care utilisation and its explanatory factors according to generational status. Methods Data from 3300 women participating in a prospective cohort of primary midwifery care clients (i.e. women with no complications or no increased risk for complications during pregnancy, childbirth and the puerperium who receive maternity care by autonomous midwives) in the Netherlands (the DELIVER study) was used. Gestational age at entry and the total number of prenatal visits were aggregated into an index. The extent to which potential factors explained non-western women’s prenatal care utilisation was assessed by means of blockwise logistic regression analyses and percentage changes in odds ratios. Results The unadjusted odds of first and second-generation non-western women making inadequate use of prenatal care were 3.26 and 1.96 times greater than for native Dutch women. For the first generation, sociocultural factors explained 43% of inadequate prenatal care utilisation, socioeconomic factors explained 33% and demographic and pregnancy factors explained 29%. For the second generation, sociocultural factors explained 66% of inadequate prenatal care utilisation. Conclusion Irrespective of generation, strategies to improve utilisation should focus on those with the following sociocultural characteristics (not speaking Dutch at home, no partner or a first-generation non-Dutch partner). For the first generation, strategies should also focus on those with the following demographic, pregnancy and socioeconomic characteristics (aged ≤19 or ≥36, unplanned pregnancies, poor obstetric histories (extra-uterine pregnancy, molar pregnancy or abortion), a low educational level, below average net household income and no supplementary insurance.(aut. ref.