227 research outputs found

    Time aspects of the European Complement to GPS: Continental and transatlantic experimental phases

    Get PDF
    The CNES project of a European Complement to GPS (CE-GPS) is conceived to fulfill the needs of Civil Aviation for a non-precise approach phase with GPS as sole navigation means. This generates two missions: a monitoring mission - alarm of failure - ,and a navigation mission - generating a GPS-like signal on board the geostationary satellites. The host satellites will be the Inmarsat constellation. The CE-GPS missions lead to some time requirements, mainly the accuracy of GPS time restitution and of monitoring clock synchronization. To demonstrate that the requirements of the CE-GPS could be achieved, including the time aspects, an experiment has been scheduled over the Last two years, using a part of the Inmarsat II F-2 payload and specially designed ground stations based on 10 channels GPS receivers. This paper presents a review of the results obtained during the continental phase of the CE-GPS experiment with two stations in France, along with some experimental results obtained during the transatlantic phase (three stations in France, French Guyana, and South Africa). It describes the synchronization of the monitoring clocks using the GPS Common-view or the C- to L-Band transponder of the Inmarsat satellite, with an estimated accuracy better than 10 ns (1 sigma)

    Teachers as Educational Innovators in Inquiry-Based Science Teaching and Learning

    Get PDF
    This chapter describes inquiry-based science teaching and learning (IBST/L) pilots designed by teachers during a professional development programme. There is research-based evidence that IBSL/T may promote students’ learning and their motivation to learn science, and therefore it is beneficial to familiarise the teachers with this approach. Building on teachers’ existing expertise in designing their teaching, the programme introduced theoretical aspects of the IBST/L approach and its research-based benefits for students’ motivation, interest and science learning. The course aimed to support teachers as educational innovators in the process of designing and testing IBST/L pilots, during which they collaboratively reflected on and revised their existing practices. The data of this piece of research consists of the teachers’ poster presentations of their IBST/L pilots and a video recording of the reflection session. The content analysis revealed that the pilots’ structure seemed traditional but encompassed some IBST/L features. It is concluded that teacher educators need to understand teachers’ views of IBST/L in order to more effectively support planning and reflection.This chapter describes inquiry-based science teaching and learning (IBST/L) pilots designed by teachers during a professional development programme. There is research-based evidence that IBSL/T may promote students’ learning and their motivation to learn science, and therefore it is beneficial to familiarise the teachers with this approach. Building on teachers’ existing expertise in designing their teaching, the programme introduced theoretical aspects of the IBST/L approach and its research-based benefits for students’ motivation, interest and science learning. The course aimed to support teachers as educational innovators in the process of designing and testing IBST/L pilots, during which they collaboratively reflected on and revised their existing practices. The data of this piece of research consists of the teachers’ poster presentations of their IBST/L pilots and a video recording of the reflection session. The content analysis revealed that the pilots’ structure seemed traditional but encompassed some IBST/L features. It is concluded that teacher educators need to understand teachers’ views of IBST/L in order to more effectively support planning and reflection.Peer reviewe

    The sport value framework - a new fundamental logic for analyses in sport management

    Get PDF
    Research question: Sports economic theory and management models have frequently been criticised for not sufficiently explaining phenomena in sport management. This article addresses this gap by proposing a conceptual framework that can be used to understand sport management problems and derive appropriate strategies. Research methods: The framework proposed in this conceptual article has been developed through a critical review of existing literature on sport management and theoretical considerations based on the service-dominant logic. Results and findings: The sport value framework (SVF) provides 10 foundational premises on value co-creation in sport management and suggests three levels for its analysis. The main contribution is a new and better theoretical basis for explaining phenomena in sport management compared with traditional sport economic thinking. Moreover, the SVF provides guidance in structuring research in sport management. Implications: The framework encourages researchers and practitioners to rethink their strategies by applying a different logic that captures the complexity of sport management. © 2014 © 2014 European Association for Sport Management

    Structural reorganization of cylindrical nanoparticles triggered by polylactide stereocomplexation

    Get PDF
    YesCo-crystallization of polymers with different configurations/tacticities provides access to materials with enhanced performance. The stereocomplexation of isotactic poly(L-lactide) and poly(D-lactide) has led to improved properties compared with each homochiral material. Herein, we report the preparation of stereocomplex micelles from a mixture of poly(L-lactide)-b-poly(acrylic acid) and poly(D-lactide)-b-poly(acrylic acid) diblock copolymers in water via crystallization-driven self-assembly. During the formation of these stereocomplex micelles, an unexpected morphological transition results in the formation of dense crystalline spherical micelles rather than cylinders. Furthermore, mixture of cylinders with opposite homochirality in either THF/H2O mixtures or in pure water at 65 °C leads to disassembly into stereocomplexed spherical micelles. Similarly, a transition is also observed in a related PEO-b-PLLA/PEO-b-PDLA system, demonstrating wider applicability. This new mechanism for morphological reorganization, through competitive crystallization and stereocomplexation and without the requirement for an external stimulus, allows for new opportunities in controlled release and delivery applications.University of Warwick, Swiss National Science Foundation and the EPSRC. The Royal Society - an Industry Fellowship to A.P.D. The Engineering and Physical Sciences Research Council (EP/G004897/1) - funding to support postdoctoral fellowships for A.P.B. as well as funding for J.S. and M.A.D. through the Warwick Centre for Analytical Science (EP/F034210/1). The Science City Research Alliance and the HEFCE Strategic Development Fund - funding support. Some items of equipment that were used in this research were funded by Birmingham Science City, with support from Advantage West Midlands and part-funded by the European Regional Development Fund

    Amphotericin B-loaded nanoparticles for local treatment of cutaneous leishmaniasis

    Get PDF
    Cutaneous leishmaniasis (CL) is an infectious, parasitic disease caused by the protozoan Leishmania. Amphotericin B (AMB) is a macrolide polyene antibiotic presenting potent antifungal and antileishmanial activity, but due to poor water solubility at physiological pH, side effects, and toxicity, its therapeutic efficiency is limited. In the present study, poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) loaded with AMB were generated to reduce drug toxicity and facilitate localized delivery over a prolonged time. AMB NPs were characterized for particle size, zeta potential, polydispersity index, and degree of aggregation. In vitro assessments demonstrated its sustained activity against Leishmania major promastigotes and parasite-infected macrophages. A single intralesional administration to infected BALB/c mice revealed that AMB NPs were more effective than AMB deoxycholate in terms of reducing lesion area. Taken together, these findings suggest thatAMB NPs improve AMB delivery and can be used for local treatment of CL.This research was funded by the GIP program of the Deutsche Forschungsgemeinschaft (DFG) German Research Foundation. EZ wish to acknowledge the financial support of the RBNI-The Russell Berrie Nanotechnology Institute at the Technion. CLJ holds the Michael and Penny Feiwel Chair of Dermatology

    Delivery modulation in silica mesoporous supports via alkyl chain pore outlet decoration

    Full text link
    This article focuses on the study of the release rate in a family of modified silica mesoporous supports. A collection of solids containing ethyl, butyl, hexyl, octyl, decyl, octadecyl, docosyl, and triacontyl groups anchored on the pore outlets of mesoporous MCM-41 has been prepared and characterized. Controlled release from pore voids has been studied through the delivery of the dye complex tris(2,2¿-bipyridyl)ruthenium(II). Delivery rates were found to be dependent on the alkyl chain length anchored on the pore outlets of the mesoporous scaffolding. Moreover, release rates follow a Higuchi diffusion model, and Higuchi constants for the different hybrid solids have been calculated. A decrease of the Higuchi constants was observed as the alkyl chain used to tune the release profile is longer, confirming the effect that the different alkyl chains anchored into the pore mouths exerted on the delivery of the cargo. Furthermore, to better understand the relation between pore outlets decoration and release rate, studies using molecular dynamics simulations employing force-field methods have been carried out. A good agreement between the calculations and the experimental observations was observed.Financial support from the Spanish Government (projects MAT2009-14564-C04-01 and MAT2009-14564-C04-04) and the Generalitat Valencia (project PROMETEO/2009/016) is gratefully acknowledged.Aznar Gimeno, E.; Sancenón Galarza, F.; Marcos Martínez, MD.; Martínez Mañez, R.; Stroeve, P.; Cano, J.; Amoros Del Toro, P. (2012). Delivery modulation in silica mesoporous supports via alkyl chain pore outlet decoration. Langmuir. 28:2986-2996. https://doi.org/10.1021/la204438jS298629962
    corecore