Estimation of roads longitudinal roughness using longitudinal profile analysor signal filtering

Experts of roads and public works have been interested for a long time in the bumps on the road ways . Such road defects with regard to a flat surface, are called the roughness of the road . The longitudinal profile analysor (LPA) was made by the « Laboratoire Central des Pants et Chaussées » in Nantes, in order to measure the roughness . The signal given by this plant can be considered as the output of a linear system whose input is the unknown longitudinal section of the road . We present in this paper two methods for solving this problem : the first one is determinist and uses a back filtering by the transfer function of the LPA. The second one is stochastic and uses Kalman filtering . At first, we modelize the LPA by a fifth order transfert function built with a description of its differents mechanic and electronic components and by an experimental frequency analysis . Then the double filtering technic eliminates the phase distortions of the LPA signal, so we obtain a pseudo profile reproduicing the exact profile with an attenuation for frequencies outside the analysor band pass . The second method uses a LPA model obtained by parametric identification (maximum likelihood method) and a model of the profile type Wiener signal . Then we implement an optimal Kalman filter. After eliminating polynomial components and low frequencies, the reconstructed signal follows accurately variations of the roughness road . Results obtained from measurements made on a test bed and an experimental way are presented .Les spécialistes du monde routier et des travaux public s'intéressent depuis longtemps aux aspérités présentes sur les chaussées. Ces défauts de la route par rapport à une surface idéalement plane constituent ce que l'on appelle son uni. L'analyseur de profil en long, l'APL, a été conçu par le Laboratoire Central des Ponts et Chaussées de Nantes afin de mesurer cet uni. Le signal que délivre cet appareil peut être considéré comme la sortie d'un système linéaire dont l'entrée est le profil inconnu de la route. Le signal que délivre cet appareil peut être considéré comme la sortie d'un système linéaire dont l'entrée est le profil de la route. L'image qu'il donne des défauts de la chaussée est déformée par rapport à la forme réelle de ces défauts, les utilisateurs sont demandeurs d'une estimation plus précise de ceux- ci. Il se pose donc le problème de la déconvolution du signal APL. Pour résoudre ce problème, on propose dans ce papier, deux approches, l'une déterministe utilisant un filtrage retour par la fonction de transfert de l'APL, l'autre stochastique par filtrage de Kalman. Dans un premier temps on modélise l'APL par une fonction de transfert du Sème ordre construite à partir d'une description des différents organes mécaniques et électroniques qui le constituent et d'une analyse harmonique expérimentale. La technique du double filtrage permet alors d'éliminer les distorsions de phases du signal APL et d'obtenir ainsi un pseudo profil qui ne diffère du profil exact que par des atténuations pour des fréquences extérieures à la bonde passante de l'analyseur. La deuxième approche utilise un modèle de l'APL obtenu par identification paramétrique (méthode du maximum de vraisemblance) et un modèle du profil du type signal de Wiener. On met alors en oeuvre un filtre estimateur optimal stationnaire de Kalman. Après élimination des composantes polynomiales et basses fréquences le signal reconstruit suit fidèlement les variations de l'uni de la chaussée. Des résultats, obtenus à partir d'enregistrements effectués au banc d'essais et sur une piste expérimentale, sont présentés

Unusual modes of action of the repellent DEET in insects highlight some human side effects

N,N-diethyl-m-toluamide (DEET) induces favorable repellency against insects by acting on the sensory nervous system. According to emerging literature reports, DEET side effects in humans involve new molecular targets including the cholinergic system, acetylcholinesterase (AChE), muscarinic M1 and M3 receptor and the participation of the second messenger nitric oxide (NO). Most of these molecular events targeted by DEET have previously been characterized in insects while they have been considered as marginal compared to classical repellent properties. Despite these uncommon actions in insects, there is no consensus on the effects in human. Based on these data, this review provides new insights on side effects in human and more largely in mammals by identifying the unusual properties of DEET in insects, which seem to be correlated with adverse effects in mammals. These data will be very helpful to understand better the toxicological effects observed in order to protect non-target organisms from the toxicity

Is cohorting the only solution to control carbapenemase-producing Enterobacteriaceae outbreaks? A single-centre experience

International audienceBACKGROUND: Carbapenemase-producing Enterobacteriaceae (CPE) are a major health issue. Cohorting may help to control spread of CPEs in hospitals, but is expensive and hard to implement.AIM: To identify ward variables associated with CPE in-hospital transmission in a hospital where cohorting has never been implemented.METHODS: Cohort prospective study, comparing 14-consecutive-day periods regarding in-hospital transmission. Each period met the two following conditions: (i) CPE carriers/infected admitted for ≥48&nbsp;h; (ii) 80% of relative contact patients were screened at least twice. Periods (a) with no acquired CPE case among relative contact patients were compared to periods (b) during which one or more CPE case acquisition was identified. Variables potentially associated with CPE transmission were assessed: colonization pressure, caregiver:patient ratio, hand hygiene compliance, hydro-alcoholic product consumption, antibiotic consumption, and infection control team (ICT) involvement on the ward.FINDINGS: Sixty-eight periods of two consecutive weeks were included, 18 (26.5%) included at least one CPE case acquisition. By multivariate analysis, colonization pressure (odds ratio: 1.12; 95% confidence interval: 1.0-1.25; P&nbsp;=&nbsp;0.042) and antibiotic consumption (2.41; 1.02-5.66; P&nbsp;=&nbsp;0.044) were associated with CPE in-hospital transmission. Caregiver:patient ratio potentiated both these variables, suggesting a role for understaffing in CPE transmission.CONCLUSION: Understanding ward variables associated with CPE spread can help design suitable solutions. Colonization pressure and antibiotic consumption seems to be driving in-hospital transmission, along with caregiver:patient ratio. In presence of high colonization pressure, dedicated healthcare workers for managing CPE patients should be implemented. Co-ordination between ICT and antimicrobial stewardship team is also crucial to prevent CPE spread.</p

Effects of uranium uptake on transcriptional responses, histological structures and survival rate of the crayfish Procambarus clarkii

This work aims to investigate the accumulation levels and effects (transcriptional responses, histopathology and survival rate) associated with a wide range of dissolved uranium (U) concentrations (0, 0.03, 0.6, 4 and 8. mg/L of U) on adult male crayfish Procambarus clarkii during 4 (T4) and 10 (T10) days of exposure. The follow-up of the crayfish mortality showed that P. clarkii was highly resistant to U. Increasing waterborne U concentrations led to increasing bioaccumulation in key crayfish organs and increasing histological damages. U distribution in tissues was also evaluated using transmission electron microscopy and showed the presence of a detoxified form of U in the gill's epithelium in the shape of flakes. Expression levels of mitochondrial genes (cox1, atp6 and 12S gene) and genes involved in oxidative stress (sod(Mn) and mt) were examined together with the housekeeping gene 18S. atp6 and mt genes of P. clarkii were cloned and sequenced before analysis. Significant correlations were observed between U bioaccumulation and the down-regulation of both cox1 and sod(Mn) genes. This work provides a first U toxicogenomic and histopathological pattern of P. clarkii, identify U biomarkers and associate gene expression endpoints to accumulation levels. It also provides new insights into the mechanisms involved in U stress. © 2011

Effects of uranium on crayfish Procambarus clarkii mitochondria and antioxidants responses after chronic exposure What have we learned?

International audienceWe examined the impacts of Uranium (U) on mitochondria and on the response of antioxidants in the gills and the hepatopancreas of crayfish Procambarus clarkii after long-term exposure (30 and 60 days) to an environmentally relevant concentration (30 μg. U/L). The expression of mitochondrial genes (12s, atp6, and cox1), as well as the genes involved in oxidative stress responses (sod(Mn) and mt) were evaluated. The activities of antioxidant enzymes (SOD, CAT, GPX and GST) were also studied. U accumulation in organs induced changes in genes' expression. The evolution of these transcriptional responses and differences between gene expression levels at high and low doses of exposure were also discussed. This study demonstrated that, after long-term exposure, U caused a decrease in antioxidant activities and induced oxidative stress. A possible ROS-mediated U cytotoxic mechanism is proposed. Expression levels of the investigated genes can possibly be used as a tool to evaluate U toxicity and seem to be more sensitive than the enzymatic activities. However a multiple biomarker approach is recommended as the perturbed pathways and the mode of action of this pollutant are not completely understood. © 2011

How toxic is the depleted uranium to crayfish Procambarus clarkii compared with cadmium?

International audienceDue to a lack of information on the assessment of uranium's (U) toxicity, our work aimed to compare the effects of U on the crayfish Procambarus clarkii with those of the well documented metal cadmium (Cd). Accumulation and impacts at different levels of biological organization were assessed after acute (40 μM Cd or U; 4-10 days) and chronic (0.1 μM Cd or U; 30-60 days) exposures. The survival rates demonstrated the high tolerance of this species toward both metals and showed that Cd had a greater effect on the sustainability of crayfish. The concentration levels of Cd and U accumulated in gills and hepatopancreas were compared between both conditions. Distinctions in the adsorption capacities and the mobility of the contaminants were suspected. Differences in the detoxification mechanisms of both metals using transmission electron microscopy equiped with an energy dispersive X-ray were also pointed out. In contrast, comparison between the histological structures of contaminated hepatopancreas showed similar symptoms. Principal component analyses revealed different impacts of each metal on the oxidative balance and mitochondria using enzymatic activities and gene expression levels as endpoints. The observation that U seemed to generate more oxidative stress than Cd in our conditions of exposure is discussed. © 2014 Wiley Periodicals, Inc