ASSESSING THE INFLUENCE OF OVERWEIGHT AXLES ON RUTTING LIVES IN FLEXIBLE PAVEMENTS USING PARAMETRIC SURVIVAL ANALYSIS

The existence of rutting or permanent deformation on flexible pavement layers has always been a concern that negatively affects the performance of roads by reducing the lifespan of pavement structure and by posing a safety risk for vehicles over the road. Traffic overloading is one of the primary factors that accelerates the deterioration of flexible pavement. This study aims to determine the time to failure of the flexible pavement structures associated with rutting, to indicate the most significant factors affecting rutting, and to assess the influence of overweight axles on pavement rutting life using parametric survival analysis. The data used in this study are extracted from the LTPP program. The outcomes provide researchers and agencies with a good knowledge of the relations between several predictors including overweight axles and pavement performance and hence increase the ability of pavement to continue functioning properly over the design lifetime. The results indicated the factors that have a significant effect on pavement rutting life. Also, the results revealed that a 1% increase in the percentage of overweight axles can be related to a 16.24% increase in the hazard rate of rutting failure. Moreover, the survival time of rutting life can be reduced by up to 63% with the increase of the percentage of overloaded axles from 0% to 20%

Single food focus dietary guidance: lessons learned from an economic analysis of egg consumption

<p>Abstract</p> <p>Background</p> <p>There is a large body of literature evaluating the impact of various nutrients of eggs and their dietary cholesterol content on health conditions. There is also literature on the costs of each condition associated with egg consumption. The goal of the present study is to synthesize what is known about the risks and benefits of eggs and the associated costs from a societal perspective.</p> <p>Methods</p> <p>A risk apportionment model estimated the increased risk for coronary heart disease (CHD) attributable to egg cholesterol content, the decreased risk for other conditions (age-related macular degeneration (AMD), cataract, neural tube defects, and sarcopenia) associated with egg consumption, and a literature search identified the cost of illness of each condition. The base 795 case scenario calculated the costs or savings of each condition attributable to egg cholesterol or nutrient content.</p> <p>Results</p> <p>Given the costs associated with CHD and the benefits associated with the other conditions, the most likely scenario associated with eating an egg a day is savings of $2.82 billion annually with uncertainty ranging from a net cost of$756 million to net savings up to $8.50 billion.</p> <p>Conclusion</p> <p>This study evaluating the economic impact of egg consumption suggests that public health campaigns promoting limiting egg consumption as a means to reduce CHD risk would not be cost-effective from a societal perspective when other benefits are considered. Public health intervention that focuses on a single dietary constituent, and foods that are high in that constituent, may lead to unintended consequences of removing other beneficial constituents and the net effect may not be in its totality a desirable public health outcome. As newer data become available, the model should be updated.</p

The SHEDS-Wood Model: Incorporation of Observational Data to Estimate Exposure to Arsenic for Children Playing on CCA-Treated Wood Structures

BACKGROUND: Lumber treated with chromated copper arsenate (CCA) compounds has been used in residential outdoor wood structures and public playgrounds. The U.S. Environmental Protection Agency (EPA) has conducted a probabilistic assessment of children’s exposure to arsenic using the Stochastic Human Exposure and Dose Simulation model for the wood preservative scenario (SHEDS-Wood). The assessment relied on data derived from an experimental study conducted using adult volunteers and designed to result in maximum hand and wipe loadings to estimate the residue–skin transfer efficiency. Recent analyses of arsenic hand-loading data generated by studies of children actively involved in playing on CCA-treated structures indicate that the transfer efficiency coefficient and hand-loading estimates derived from the experimental study significantly overestimate the amount that occurs during actual play. OBJECTIVES: Our goal was to assess the feasibility of using child hand-loading data in the SHEDS-Wood model and their impact on exposure estimates. METHODS: We used data generated by the larger of the studies of children in SHEDS-Wood, instead of the distributions used by U.S. EPA. We compared our estimates of the lifetime average daily dose (LADD) and average daily dose (ADD) with those derived by the U.S. EPA. RESULTS: Our analysis indicates that data from observational studies of children can be used in SHEDS-Wood. Our estimates of the mean (and 95th percentile) LADD and ADD were 27% (10%) and 29% (15%) of the estimates derived by U.S. EPA. CONCLUSION: We recommend that the SHEDS-Woods model use data from studies of children actively playing on playsets to more accurately estimate children’s actual exposures to CCA

Motion dynamics of Si (100) positive and negative islands under electromigration and thermomigration

International audienceMass transport processes play an important role in nano devices. They determine the morphology and the stability of a working device, and eventually its lifetime. When a direct electric current is applied to a material, it affects the mass transport by adding a bias to the atomic diffusive motion. This effect, called electromigration, can play an important role on the dynamics and the morphological stability of nanostructures at surfaces. In this work we have studied the motion of single-step holes and islands under the effect of an electric field on Si(100), in real time, by Low Energy Electron Microscopy (LEEM). The details of the motion depend on the strong diffusion anisotropy of the Si dimer rows. Studying the velocity and the shape of the nanostructures, we discuss a model to explain and guide the motion of holes and islands. Electron energy lower than 20 eV High imaging dynamics (0.1 s per image) LEEM This work was performed in the framework of the ANR grant HOLOLEEM (ANR-15-CE09-0012). We are grateful to B. Ranguelov and M. Michailov for stimulating discussions had in the framework of the PHC Rila project (38663TB)) project. The poster is based on the paper: "2D nanostructure motion on anisotropic surfaces controlled by electromigration", S. Curiotto

Evaluation of Exposure to Arsenic in Residential Soil

In response to concerns regarding arsenic in soil from a pesticide manufacturing plant, we conducted a biomonitoring study on children younger than 7 years of age, the age category of children most exposed to soil. Urine samples from 77 children (47% participation rate) were analyzed for total arsenic and arsenic species related to ingestion of inorganic arsenic. Older individuals also provided urine (n = 362) and toenail (n = 67) samples. Speciated urinary arsenic levels were similar between children (geometric mean, geometric SD, and range: 4.0, 2.2, and 0.89–17.7 μg/L, respectively) and older participants (3.8, 1.9, 0.91–19.9 μg/L) and consistent with unexposed populations. Toenail samples were < 1 mg/kg. Correlations between speciated urinary arsenic and arsenic in soil (r = 0.137, p = 0.39; n = 41) or house dust (r = 0.049, p = 0.73; n = 52) were not significant for children. Similarly, questionnaire responses indicating soil exposure were not associated with increased urinary arsenic levels. Relatively low soil arsenic exposure likely precluded quantification of arsenic exposure above background

Un modèle analytique d'homogénéisation 3D complet pour les plaques composites orthotropes de type carton ondulé

La modélisation des plaques composites en carton ondulé est fastidieuse et couteuse en temps CPU. On propose un modèle d'homogénéisation analytique 3D complet en 2 étapes. A la première étape, on détermine les rigidités globales d'une plaque homogène équivalente. A la deuxième étape, on retransforme la plaque homogénéisée en un solide orthotrope composé de plusieurs couches et on identifie les paramètres des matériaux à partir de ces rigidités globales pour prendre en compte le comportement élasto-plastique suivant l'épaisseur. Le modèle est validé à l'aide du logiciel Abaqus

Refinement of arsenic attributable health risks in rural Pakistan using population specific dietary intake values

Background: Previous risk assessment studies have often utilised generic consumption or intake values when evaluating ingestion exposure pathways. If these values do not accurately reflect the country or scenario in question, the resulting risk assessment will not provide a meaningful representation of cancer risks in that particular country/scenario. Objectives: This study sought to determine water and food intake parameters for one region in South Asia, rural Pakistan, and assess the role population specific intake parameters play in cancer risk assessment. Methods: A questionnaire was developed to collect data on sociodemographic features and 24-hour water and food consumption patterns from a rural community. The impact of dietary differences on cancer susceptibility linked to arsenic exposure was evaluated by calculating cancer risks using the data collected in the current study against standard water and food intake levels for the USA, Europe and Asia. A probabilistic cancer risk was performed for each set of intake values of this study. Results: Average daily total water intake based on drinking direct plain water and indirect water from food and beverages was found to be 3.5 L day-1 (95% CI: 3.38, 3.57) exceeding the US Environmental Protection Agency’s default (2.5 L day-1) and World Health Organization’s recommended intake value (2 L day-1). Average daily rice intake (469 g day-1) was found to be lower than in India and Bangladesh whereas wheat intake (402 g day−1) was higher than intake reported for USA, Europe and Asian sub-regions. Consequently, arsenic-associated cumulative cancer risks determined for daily water intake was found to be 17 in children of 3-6 years (95% CI: 0.0014, 0.0017), 14 in children of age 6-16 years (95% CI: 0.001, 0.0011) and 6 in adults of 16-67 years (95% CI: 0.0006, 0.0006) in a population size of 10000. This is higher than the risks estimated using the US Environmental Protection Agency and World Health Organization’s default recommended water intake levels. Rice intake data showed early life cumulative cancer risks of 15 in 10000 for children of 3-6 years (95% CI: 0.0012, 0.0015), 14 in children of 6-16 years (95% CI: 0.0011, 0.0014) and later life risk of 8 in adults (95% CI: 0.0008, 0.0008) in a population of 10000. This is lower than cancer risks in countries with higher rice intake and elevated arsenic levels (Bangladesh and India). Cumulative cancer risk from arsenic exposure showed the relative risk contribution from total water to be51%, from rice to be44% and wheat intake 5%. Conclusions: The study demonstrates the need to use population specific dietary information for risk assessment and risk management studies. Probabilistic risk assessment concluded the importance of dietary intake in estimating cancer risk, along with arsenic concentrations in water or food and age of exposed rural population

Genetics of tomato fruit cuticle development and composition

A total of 60 QTLs were identified, indicating that all the cuticle traits analyzed have a complex polygenic nature. A combination of additive and epistatic interactions was observed for all the traits, with positive contribution of either both parental lines to most of them. Colocalization of QTLs for various traits uncovered novel genomic regions producing extensive changes in the cuticle composition and color. Two genomic regions, located in chromosomes 1 and 12, were found to be responsible for the negative relationship between cuticle waxes and phenolics percentage contents. Several candidate genes, including transcription factors and structural genes, are postulated and their expression analyzed throughout development. We also pyramided several of the phenolic content-related QTLs from the S. pimpinellifolium accession into the genetic background of the cultivated tomato with the aid of single nucleotide polymorphisms (SNP) molecular markers, polymorphic between both parental lines. Our pyramiding strategy resulted in 23 new introgression lines, combining more than one QTL for cuticle phenolics in the genetic background of the cultivated tomato to produce new genetic materials with higher or lesser cuticle flavonoid content. The interactions between the combined QTLs were also dissected and the interactions, either additive or epistatic, of each created combination was identified. Accumulation of phenolics QTLs was only partially effective in reducing phenolics in the cuticle since no QTL-combined line showed phenolic content comparable to that of TO-937. Results of pyramided QTLs emphasized that the genetic control of phenolics-related traits was very complex, and epistatic interactions changed the expected outcome of several of the QTLs depending on the specific alleles of the combined QTLs.The plant cuticle, as the interface between the plant and the environment, plays an important role in plant performance, fruit quality and postharvest. Plant cuticles show compositional and structural variability among and within species and also between organs of the same species. It is composed by a cutin polymer matrix with waxes that can be accumulated on the surface (epicuticular waxes) or embedded in the matrix (intracuticular waxes), phenolics and polysaccharides from the cell wall. In tomato fruit cuticle, the phenolic fraction is a characteristic component and is the main modulator of the cuticle’s stiffness, deformation and strength. This phenolic domain is composed of cinnamic acids derivatives present during fruit growth and increases significantly during ripening with the incorporation of the flavonoid naringenin chalcone, responsible for the yellow-orange color of the cuticle in red ripe tomatoes. Understanding the genetic basis of cuticle composition and color is needed for breeding in crop species. Little is known about the range and the genetic bases of naturally occurring variation for cuticle composition and structure in tomato. The general objective of this work is to dissect the genetic architecture underlying these variations and to exploit available natural genetic diversity in wild species to transfer the beneficial alleles affecting cuticle-associated traits to commercial varieties. In this work, we have explored for the first time the cuticle variability of red-fruited species in two mapping populations derived from the interspecific cross between the domesticated tomato (Solanum lycopersicum L.) and its closest wild relative Solanum pimpinellifolium L., a Recombinant Inbred Line population and an Introgression Line population. Quantitative trait locus (QTL) analyses were conducted to investigate tomato fruit cuticle components and color traits