Bordeaux, France
Bordeaux, France
Time filter
Source Type

Bui T.H.,URCA | Pradon D.,French Institute of Health and Medical Research | Lestriez P.,URCA | Debray K.,URCA | And 2 more authors.
Proceedings of the 13th IASTED International Conference on Biomedical Engineering, BioMed 2017 | Year: 2017

It is well-known that improvements in seat comfort are needed as a medical solution to prevent pressure ulcers. In recent years, pressure ulcers have become an increasing social and medical issue and manufacturers are trying to respond appropriately for better solutions. The contact interaction between human buttock-tissue and seat cushion is an important factor in users' sense of comfort. In this study, an approach by experimental method with pressure mapping (TexiMat) will be analyzed for eight different cushions in the aim to compare their behaviors in sitting position. The comportment of buttocks/cushions model was validated by experimental data. The main purpose of this article is to study the influence of material properties contributions on cushions and their capacities to reduce pressure distribution by improving the ability to prevent pressure ulcers. This study may help to choose different types of cushions as well as the thickness of the cushions for patients and user's wheelchair to prevent pressure ulcers. © 2017 International Association of Science and Technology for Development - IASTED.

Prado L.A.C.D.,Federal University of Pernambuco | Pereira P.A.,Federal University of Pernambuco | Sales A.M.F.,URCA | Barreto A.M.F.,Federal University of Pernambuco
Journal of South American Earth Sciences | Year: 2015

Benthic macroinvertebrate fossils can be seen towards to the top of the Romualdo Member of the Santana Formation, in the Araripe Basin, Northeast Brazil, and can provide paleoenvironmental and paleobiogeographical information regarding the Cretaceous marine transgression which reached the interior basins in Northeast Brazil. We analyse taphonomic characteristics of macroinvertebrate concentrations of two outcrops (Torrinha and Torre Grande) within the municipality Araripina, Pernambuco, in order to enhance our understanding of the Cretaceous paleoenvironment in the western portion of the Araripe Basin. At the outcrop Torrinha, proximal tempestitic taphofacies were identified. These predominantly consist of ceritid, cassiopid, and later, naticid gastropods as well as undetermined bivalves. Given this lack of variability it can be deduced that there were no significant paleoenvironmental changes during the successive stages tempestitic sedimentation. In the Torre Grande outcrop distal to proximal tempestitic taphofacies were identified from the base to the top respectively pointing to a decrease in paleodepth. Asides from the macroinvertebrates present in Torrinha, there are also echinoids - unequivocal evidence for marine conditions. These occurrences appear to be restricted to Romualdo Member outcrops in the Araripina municipality (the Southeast portion of the Araripe Basin) confirming a previously published hypothesis suggesting that the Cretaceous marine transgression originated from the neighbouring Parnaíba Basin to the west. This study identified marine molluscs of a similar age to those in the Romualdo Member's equivalent rock units in the Parnaíba and Sergipe-Alagoas (SE-AL) basins suggesting a marine connection between these basins and the Araripe Basin during the Early Cretaceous. © 2015 Elsevier Ltd.

Bertrand I.,French National Institute for Agricultural Research | Ehrhardt F.,French National Institute for Agricultural Research | Alavoine G.,French National Institute for Agricultural Research | Joulian C.,Bureau de Recherches Géologiques et Minières | And 2 more authors.
Soil Biology and Biochemistry | Year: 2014

The occurrence and diversity of biological soil crusts (BSC) a thin soil surface layer composed of phototrophic and heterotrophic microorganisms intimately associated with soil particles, are known as strong indicators of ecosystem health and sensitivity to soil surface disturbances and are key factors in the biochemical cycling of carbon and nitrogen in drylands. However, the impact of land use on C and N budgets related to BSC dynamics is poorly understood and hinders the prediction of changes in soil fertility in response to future land use scenarios. In this study, we examined the C and N exchange rates of BSC sampled along a north-south pluviometric gradient of the Sub-Sahel, which provides evidence of increasing human land pressure, leading to a gradient in fallow duration and trampling intensity. We demonstrate that the net and gross photosynthesis by BSC significantly increases with fallow duration and a reduction of trampling intensity, thus affecting BSC fine particles and relative water content. Conversely, no effect of land use was found on N fixation or mineralisation rates, which are instead regulated by the N availability within the crust. Simple statistical models were derived from the relationships between C exchange rates and BSC intrinsic characteristics related to soil surface disturbances. The proposed statistical models were tested for C gas exchange with independent data obtained from a new BSC dataset sampled in Burkina Faso and Niger. A simple equation using BSC fine particle content as a unique variable was found to explain between 60 and 70% of the gross photosynthesis. Our findings will help in mapping photosynthesis and estimating the contribution of BSC to the carbon budget at a regional scale in the dryland area of the Sahel and to further testing of land use change scenarios. © 2014 Elsevier Ltd.

Cosson J.-F.,French National Institute for Agricultural Research | Michelet L.,French National Institute for Agricultural Research | Chotte J.,French National Institute for Agricultural Research | Le Naour E.,French National Institute for Agricultural Research | And 8 more authors.
Parasites and Vectors | Year: 2014

Background: In France as elsewhere in Europe the most prevalent TBD in humans is Lyme borreliosis, caused by different bacterial species belonging to Borrelia burgdorferi sensu lato complex and transmitted by the most important tick species in France, Ixodes ricinus. However, the diagnosis of Lyme disease is not always confirmed and unexplained syndromes occurring after tick bites have become an important issue. Recently, B. miyamotoi belonging to the relapsing fever group and transmitted by the same Ixodes species has been involved in human disease in Russia, the USA and the Netherlands. In the present study, we investigate the presence of B. miyamotoi along with other Lyme Borreliosis spirochetes, in ticks and possible animal reservoirs collected in France. Methods. We analyzed 268 ticks (Ixodes ricinus) and 72 bank voles (Myodes glareolus) collected and trapped in France for the presence of DNA from B. miyamotoi as well as from Lyme spirochetes using q-PCR and specific primers and probes. We then compared the French genotypes with those found in other European countries. Results: We found that 3% of ticks and 5.55% of bank voles were found infected by the same B. miyamotoi genotype, while co-infection with other Lyme spirochetes (B. garinii) was identified in 12% of B. miyamotoi infected ticks. Sequencing showed that ticks and rodents carried the same genotype as those recently characterized in a sick person in the Netherlands. Conclusions: The genotype of B. miyamotoi circulating in ticks and bank voles in France is identical to those already described in ticks from Western Europe and to the genotype isolated from a sick person in The Netherlands. This results suggests that even though no human cases have been reported in France, surveillance has to be improved. Moreover, we showed that ticks could simultaneously carry B. miyamotoi and Lyme disease spirochetes, increasing the problem of co-infection in humans. © 2014 Cosson et al.; licensee BioMed Central Ltd.

Rammal A.,URCA | Fenniri H.,URCA | Goupil A.,URCA | Chabbert B.,French National Institute for Agricultural Research | And 2 more authors.
2015 23rd European Signal Processing Conference, EUSIPCO 2015 | Year: 2015

Infrared spectroscopy can provide useful information of the biomass composition and has been extensively used in several domains such as biology, food science, pharmaceutical, petrochemical, agricultural applications, etc. However, not all spectral information are valuable for biomarkers construction or for applying regression or classification models and by identifying interesting wavenumbers a better processing and interpretation can be achieved. The selection of optimal subsets has been addressed through several variable or feature selection methods including genetic algorithms. Some of them are not adapted on large data, others require additional information such as concentrations or are difficult to tune. This paper proposes an alternative approach by considering a weighted Euclidean distance. We show on real Mid-infrared spectra that this constrained nonlinear optimizer allows identifying the wavenumbers that best highlights the discrimination within the periods of the biodegradation process of the ligno-cellulosic biomass. These results are compared with previous ones obtained by a genetic algorithm. © 2015 EURASIP.

Furtado I.P.,URCA | De Moraes G.J.,University of Sao Paulo | Kreiter S.,Montpellier SupAgro | Flechtmann C.H.W.,University of Sao Paulo | And 2 more authors.
Acarologia | Year: 2014

The fauna of phytoseiid mites in the state of Mato Grosso do Sul, in midwestern Brazil, is poorly known. The tomato red spider mite, Tetranychus evansi Baker and Pritchard, is an important pest of Solanaceae in several countries, but it is usually found in low densities in Brazil. It has been hypothesized that this is due to the effect of natural enemies. The objective of this study was to identify phytoseiid mites from Mato Grosso do Sul associated with T. evansi, to identify promising biological control agents for T. evansi in Africa. A survey was conducted in October – November 2002, sampling more than 70 plant species of 30 families, including 16 solanaceous species. The results of this survey provide some additional information to the scant knowledge on the phytoseiids from Mato Grosso do Sul. In total, 471 phytoseiids were collected, belonging to 12 Amblyseiinae and two Phytoseiinae species. The most frequent and abundant species was Euseius citrifolius Denmark and Muma, followed by Euseius concordis (Chant). Also, 3,493 tetranychids were found. Tetranychus evansi was found in Aquidauna on Solanum americanum (Miller), associated with E. citrifolius and Ty-phlodromalus aripo De Leon; in Corumbá, on S. americanum associated with E. concordis and Neoseiulus idaeus Denmark and Muma; and in Dourados, on Solanum lycopersicum (L.), associated with E. citrifolius, Proprioseiopsis mexicanus (Garman) and Proprioseiopsis ovatus (Garman). However, none of the phytoseiids found are considered to be a promising biological control agent of T. evansi, based on both their inconsistent association with the pest and on available information about each species. © Furtado I.P. et al.

Leroux O.,Ghent University | Bagniewska-Zadworna A.,Adam Mickiewicz University | Rambe S.K.,Nanyang Technological University | Knox J.P.,University of Leeds | And 7 more authors.
Annals of Botany | Year: 2011

• Background and Aims: Extraxylary helical cell wall thickenings in vascular plants are not well documented, except for those in orchid velamen tissues which have been studied extensively. Reports on their occurrence in ferns exist, but detailed information is missing. The aim of this study is to focus on the broad patterns of structure and composition and to study the taxonomic occurrence of helical cell wall thickenings in the fern family Aspleniaceae. • Methods: Structural and compositional aspects of roots have been examined by means of light, electron, epifluorescence and laser scanning confocal microscopy. To assess the taxonomical distribution of helical cell wall thickenings a molecular phylogenetic analysis based on rbcL sequences of 64 taxa was performed. • Key Results: The helical cell wall thickenings of all examined species showed considerable uniformity of design. The pattern consists of helical, regularly bifurcating and anastomosing strands. Compositionally, the cell wall thickenings were found to be rich in homogalacturonan, cellulose, mannan and xyloglucan. Thioacidolysis confirmed our negative phloroglucinol staining tests, demonstrating the absence of lignins in the root cortex. All taxa with helical cell wall thickenings formed a monophyletic group supported by a 100% bootstrap value and composed of mainly epiphytic species. • Conclusions: This is the first report of non-lignified pectin-rich secondary cell walls in ferns. Based on our molecular analysis, we reject the hypothesis of parallel evolution of helical cell wall thickenings in Aspleniaceae. Helical cell wall thickenings can mechanically stabilize the cortex tissue, allowing maximal uptake of water and nutrients during rainfall events. In addition, it can also act as a boundary layer increasing the diffusive pathway towards the atmosphere, preventing desiccation of the stele of epiphytic growing species. © The Author 2010. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.

Labergere C.,French National Center for Scientific Research | Saanouni K.,French National Center for Scientific Research | Lestriez P.,URCA
Key Engineering Materials | Year: 2010

The influence of the initial temperature and its evolution with large plastic deformation on the formation of the fully coupled chevron shaped cracks in extrusion is numerically investigated. Fully coupled thermo-elasto- viscoplastic constitutive equations accounting for thermal effects, mixed and nonlinear isotropic and kinematic hardening, isotropic ductile damage with micro-cracks closure effects are used. These constitutive equations have been implemented in Abaqus/Explicit code thanks to the user subroutine vumat and used to perform various numerical simulations needed to investigate the problem. It has been shown that the proposed methodology is efficient to predict the chevron shaped cracks in extrusion function of the main process parameters including the temperature effect. © (2010) Trans Tech Publications.

Gomes R.V.R.S.,Federal Rural University of Pernambuco | Vilela V.L.R.,Federal University of Campina Grande | Gomes E.N.,Federal University of Campina Grande | Maia A.J.,URCA | Athayde A.C.R.,Federal University of Campina Grande
Revista Caatinga | Year: 2011

The preliminary investigation of chemical constituents of a plant allows the prior knowledge of the extract and indicates the nature of the present substances. The aim of this paper was to detect the absence or presence of appreciable amounts of various chemical constituents in extracts of jurubeba [Solanum paniculatum Linnaeus (1762)], capim santo [Cymbopogon citratus Stapf (1906)], batata de purga [Operculina hamiltonii (G. DON) D.F. Austin & Staples (1983)] and melão de são caetano [Momordica charantia Linnaeus (1763)], which has been indicated as alternative treatment against gastrintestinal helmintiasis of small ruminants. The jurubeba was collected in the city of Teixeira - PB. The capim santo, the batata de purga and the melão de são caetano were collected at the Centro de Saúde e Tecnologia Rural/UFCG, Patos - PB, in august and september of 2008. After, was realized the identification of the indicated shares to the ethnopharmacology study, deposited in the Herbário Caririense Dárdano de Andrade - Lima of the Universidade Regional do Cariri-URCA. The acquisition of the extract and phytochemical study followed the methodology described by Matos (1997). To obtain the extract was used the dust of the shares collected from each plant and as solvent ethanol PA. Four tests (phenols and tannins; anthocyanins, anthocyanidins and flavonoids; leucoanthocyanidins, catechins and flavanones; and alkaloids.) were conducted for the exploration of hydroalcoholical constituents. In the chemical assay were concluded that the ethanol extracts of the four plants with compounds such as tannins and catechins, and absence of phenols, anthocyanins and proanthocyanidins.

Demangel C.,CRITT MDTS | Poznanski A.,CRITT MDTS | Steenhout V.,CRITT MDTS | Levesque A.,URCA | And 2 more authors.
Advanced Materials Research | Year: 2014

In this work, the use of a nanocrystallization surface treatment is considered on a cobalt based alloy. Since the Co28Cr6Mo is widely used as an articular bearing surface for artificial joints like hip and knee prostheses, the improvement of its tribological properties is a matter of concern to extend the lifespan of implants. By means of SMA (Surface Mechanical Attrition) treatment, a nanostructured layer is formed at the surface of a CoCrMo alloy establishing an optimized hardness gradient down to a depth of a few hundred of microns. Different treatment times (5, 15 and 25 minutes) are assessed comparatively and several surface polishing methods are studied: with clothes, brushes and a liquid filled with abrasive particles. The influence of processing parameters is discussed regarding hardness and topography. Moreover, the impact of surface modification is examined in terms of wear strengthening through scratch testing. The use of increasing loads mode gives some evidence of the benefit of SMAT. A significant decrease of penetration depth is noticed, from 30% to 60% on average. A straight correlation is also noticed depending on the surface finish method. This study illustrates both the ability of micro scratch testing to assess comparatively treated surface layer and to highlight the benefit of SMAT for wear strengthening in an abrasive wear mode. © (2014) Trans Tech Publications, Switzerland.

Loading URCA collaborators
Loading URCA collaborators