2,964 research outputs found

    Multilayer chromium based coatings grown by atmospheric pressure direct liquid injection CVD

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    There is a great interest for multilayer hard coatings because they exhibit enhanced properties resulting from their nanostructuration. Such coatings are frequently constituted of carbide and nitride and are generally deposited under very low pressure by plasma and PVD processes. These vacuum techniques enable the growth of heterostructures with nanometric thick individual layers and sharp interfaces, which are two requirements for advanced performances. However, both to develop more economical processes and with the goal of continuous deposition applications, the CVD processes operating under atmospheric pressure are particularly attractive. In this paper we show that the combination of pulsed direct liquid injection and the use of metalorganic precursor (DLI-MOCVD) is a promising route for the growth of nanostructured multilayer coatings under atmospheric pressure. Chromium metal as well as chromium carbide and nitrides monolithic coatings have been deposited at 773 K by this process using liquid solution of bis(benzene) chromium as Cr molecular precursor. Then, CrCx/CrN nanostructured multilayer coatings with a bilayer period as low as 50 nm have been grown. Structural characterizations and preliminary mechanical properties of these metallurgical coatings are discussed

    Impaired EAT-4 vesicular glutamate transporter leads to defective nocifensive response of caenorhabditis elegans to noxious heat

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    In mammals, glutamate is an important excitatory neurotransmitter. Glutamate and glutamate receptors are found in areas specifically involved in pain sensation, transmission and transduction such as peripheral nervous system, spinal cord and brain. In C. elegans, several studies have suggested glutamate pathways are associated with withdrawal responses to mechanical stimuli and to chemical repellents. However, few evidences demonstrate that glutamate pathways are important to mediate nocifensive response to noxious heat. The thermal avoidance behavior of C. elegans was studied and results illustrated that mutants of glutamate receptors (glr-1, glr-2, nmr-1, nmr-2) behaviors was not affected. However, results revealed that all strains of eat-4 mutants, C. elegans vesicular glutamate transporters, displayed defective thermal avoidance behaviors. Due to the interplay between the glutamate and the FLP-18/FLP-21/NPR-1 pathways, we analyzed the effectors FLP-18 and FLP-21 at the protein level, we did not observebiologically significant differences compared to N2 (WT) strain (fold-change < 2) except for the IK602 strain. The data presented in this manuscript reveals that glutamate signaling pathways are essential to elicit a nocifensive response to noxious heat in C. elegans

    Lived Disablers to Academic Success of the Visually Impaired at the University of Zambia, Sub‑Saharan Africa

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    The World Health Organization’s (WHO) benchmark of persons with disability in every population is 15.6 per cent. However, the University of Zambia is way below that benchmark as it is home to less than 0.1 per cent of students classified as ‘disabled’. Within the 0.1 per cent, students with visual impairment are the majority, estimated at 70 per cent. The purpose of this study was to explore disablers (also known as barriers) to academic success faced by students with visual impairment at the University of Zambia. A Hermeneutic Phenomenological approach directed the research process. Seven purposively sampled participants volunteered to voice their lived experiences and a cluster of themes emerged thereafter. Emerging from their lived experiences are thirteen disablers that impede the learning experiences at University and key amongst them are: (i) negative attitudes; (ii) policypractice disjuncture; (iii) staff unreadiness and unpreparedness; (iv) inaccessible buildings; and (v) rigid curricula. Keywords: disablers; Hermeneutic Phenomenology; inclusive education; University of Zambia; visual impairmen

    Identification and temporal expression of putative circadian clock transcripts in the amphipod crustacean Talitrus saltator

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    Background Talitrus saltator is an amphipod crustacean that inhabits the supralittoral zone on sandy beaches in the Northeast Atlantic and Mediterranean. T. saltator exhibits endogenous locomotor activity rhythms and time-compensated sun and moon orientation, both of which necessitate at least one chronometric mechanism. Whilst their behaviour is well studied, currently there are no descriptions of the underlying molecular components of a biological clock in this animal, and very few in other crustacean species. Methods We harvested brain tissue from animals expressing robust circadian activity rhythms and used homology cloning and Illumina RNAseq approaches to sequence and identify the core circadian clock and clock-related genes in these samples. We assessed the temporal expression of these genes in time-course samples from rhythmic animals using RNAseq. Results We identified a comprehensive suite of circadian clock gene homologues in T. saltator including the ‘core’ clock genes period (Talper), cryptochrome 2 (Talcry2), timeless (Taltim), clock (Talclk), and bmal1 (Talbmal1). In addition we describe the sequence and putative structures of 23 clock-associated genes including two unusual, extended isoforms of pigment dispersing hormone (Talpdh). We examined time-course RNAseq expression data, derived from tissues harvested from behaviourally rhythmic animals, to reveal rhythmic expression of these genes with approximately circadian period in Talper and Talbmal1. Of the clock-related genes, casein kinase IIβ (TalckIIβ), ebony (Talebony), jetlag (Taljetlag), pigment dispensing hormone (Talpdh), protein phosphatase 1 (Talpp1), shaggy (Talshaggy), sirt1 (Talsirt1), sirt7 (Talsirt7) and supernumerary limbs (Talslimb) show temporal changes in expression. Discussion We report the sequences of principle genes that comprise the circadian clock of T. saltator and highlight the conserved structural and functional domains of their deduced cognate proteins. Our sequencing data contribute to the growing inventory of described comparative clocks. Expression profiling of the identified clock genes illuminates tantalising targets for experimental manipulation to elucidate the molecular and cellular control of clock-driven phenotypes in this crustacean

    Lived Disablers to Academic Success of the Visually Impaired at the University of Zambia, Sub‑Saharan Africa

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    The World Health Organization’s (WHO) benchmark of persons with disability in every population is 15.6 per cent. However, the University of Zambia is way below that benchmark as it is home to less than 0.1 per cent of students classified as ‘disabled’. Within the 0.1 per cent, students withvisual impairment are the majority, estimated at 70 per cent. The purpose of this study was to explore disablers (also known as barriers) to academic success faced by students with visual impairment at the University of Zambia. A Hermeneutic Phenomenological approach directed the research process.Seven purposively sampled participants volunteered to voice their lived experiences and a cluster of themes emerged thereafter. Emerging from their lived experiences are thirteen disablers that impede the learning experiences at University and key amongst them are: (i) negative attitudes; (ii) policypractice disjuncture; (iii) staff unreadiness and unpreparedness; (iv) inaccessible buildings; and (v) rigid curricula

    3-D Magnetotelluric Investigations for geothermal exploration in Martinique (Lesser Antilles). Characteristic Deep Resistivity Structures, and Shallow Resistivity Distribution Matching Heliborne TEM Results

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    Within the framework of a global French program oriented towards the development of renewable energies, Martinique Island (Lesser Antilles, France) has been extensively investigated (from 2012 to 2013) through an integrated multi-methods approach, with the aim to define precisely the potential geothermal ressources, previously highlighted (Sanjuan et al., 2003). Amongst the common investigation methods deployed, we carried out three magnetotelluric (MT) surveys located above three of the most promising geothermal fields of Martinique, namely the Anses d'Arlet, the Montagne Pel{\'e}e and the Pitons du Carbet prospects. A total of about 100 MT stations were acquired showing single or multi-dimensional behaviors and static shift effects. After processing data with remote reference, 3-D MT inversions of the four complex elements of MT impedance tensor without pre-static-shift correction, have been performed for each sector, providing three 3-D resistivity models down to about 12 to 30 km depth. The sea coast effect has been taken into account in the 3-D inversion through generation of a 3-D resistivity model including the bathymetry around Martinique from the coast up to a distance of 200 km. The forward response of the model is used to calculate coast effect coefficients that are applied to the calculated MT response during the 3-D inversion process for comparison with the observed data. 3-D resistivity models of each sector, which are inherited from different geological history, show 3-D resistivity distribution and specificities related to its volcanological history. In particular, the geothermal field related to the Montagne Pel{\'e}e strato-volcano, is characterized by a quasi ubiquitous conductive layer and quite monotonic typical resistivity distribution making interpretation difficult in terms of geothermal targets. At the opposite, the resistivity distribution of Anse d'Arlet area is radically different and geothermal target is thought to be connected to a not so deep resistive intrusion elongated along a main structural axis. Beside these interesting deep structures, we demonstrate, after analyzing the results of the recent heliborne TEM survey covering the whole Martinique, that surface resistivity distribution obtained from 3-D inversion reproduce faithfully the resistivity distribution observed by TEM. In spite of a very different sampling scale, this comparison illustrates the ability of 3-D MT inversion to take into account and reproduce static shift effects in the sub-surface resistivity distribution.Comment: Wordl Geothermal Congress 2015, Apr 2015, Melbourne, Australi
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