22,429 research outputs found

    FIC/FEM formulation with matrix stabilizing terms for incompressible flows at low and high Reynolds numbers

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    The final publication is available at Springer via http://dx.doi.org/10.1007/s00466-006-0060-yWe present a general formulation for incompressible fluid flow analysis using the finite element method. The necessary stabilization for dealing with convective effects and the incompressibility condition are introduced via the Finite Calculus method using a matrix form of the stabilization parameters. This allows to model a wide range of fluid flow problems for low and high Reynolds numbers flows without introducing a turbulence model. Examples of application to the analysis of incompressible flows with moderate and large Reynolds numbers are presented.Peer ReviewedPostprint (author's final draft

    NASA LeRC's Acoustic Fill Effect Test Program and Results

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    NASA Lewis Research Center, in conjunction with General Dynamics Space Systems Division, has performed a test program to investigate the acoustic fill effect for an unblanketed payload fairing for a variety of payload simulators. This paper will discuss this test program and fill factor test data, and make comparisons with theoretical predictions. This paper will also address the NASA acoustic fill effect standard which was verified from the test data analysis

    Microplastics in the Antarctic marine system: An emerging area of research

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    It was thought that the Southern Ocean was relatively free of microplastic contamination; however, recent studies and citizen science projects in the Southern Ocean have reported microplastics in deep-sea sediments and surface waters. Here we reviewed available information on microplastics (including macroplastics as a source of microplastics) in the Southern Ocean. We estimated primary microplastic concentrations from personal care products and laundry, and identified potential sources and routes of transmission into the region. Estimates showed the levels of microplastic pollution released into the region from ships and scientific research stations were likely to be negligible at the scale of the Southern Ocean, but may be significant on a local scale. This was demonstrated by the detection of the first microplastics in shallow benthic sediments close to a number of research stations on King George Island. Furthermore, our predictions of primary microplastic concentrations from local sources were five orders of magnitude lower than levels reported in published sampling surveys (assuming an even dispersal at the ocean surface). Sea surface transfer from lower latitudes may contribute, at an as yet unknown level, to Southern Ocean plastic concentrations. Acknowledging the lack of data describing microplastic origins, concentrations, distribution and impacts in the Southern Ocean, we highlight the urgent need for research, and call for routine, standardised monitoring in the Antarctic marine system

    Skill Acquisition and Development Issues with Predictable Badminton Feeding Routines

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    Badminton practice designs contain feeding routines that allow players to practice technical skills. Optimal skill acquisition and development is gained through practice simulating competitive match play rather than approaches centred around mass repetition with low levels of uncertainty. This study aimed to evaluate the biomechanical differences in twelve youth elite UK badminton players in activities with varying levels of predictability. The three experimental trials were handfeed, multifeed and match play trials. Motion capture cameras were used to record participant biomechanical data. Data analysis revealed several significant biomechanical differences between trials. Results showed that an increase in trial unpredictability led to increased depth of the forward lunge shot and a lower racket shuttlecock strike position with greater forward trunk bend. This study showed that visual search behaviour in badminton is a key component of the forward lunge shot. Predictable practice feeding routines may cause poor skill acquisition and development through maladaptive learning behaviours. Coaches are recommended to implement unpredictable feeding practice routines to simulate the visual search behaviour of competitive badminton match play to enhance skill acquisition and development in youth elite badminton players

    Production of Polyclonal Antibodies Against a Yam Isolate of Cucumber Mosaic Virus (Cmv).

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    Cucumber mosaic virus (CMV) genus Cucumovirus was recently detected in yam in Ghana, Togo and Benin bringing to six the total number of countries reporting CMV infection in yam worldwide. Two serotypes of CMV are distinguished and a specific antibody against the yam isolate of CMV is currently not available. Rabbit polyclonal antibodies were produced against purified preparations of a yam isolate of CMV from Nigeria. The antibody titre was determined by Protein-A sandwich (PAS) enzymelinked immunosorbent assay (ELISA) and antigen-coated plate (ACP) ELISA. Antigen detection limit of the antibody was determined by PAS-ELISA using serial dilutions of infected sap. The CMV antiserum produced had a titre of 1:25,600 and 1:64,000 by PAS- and ACP-ELISA, respectively and a sap dilution end point of 1:160. The antibody detected homologous antigen in infected yam leaves from Ghana, Togo, Benin and Nigeria. The CMV polyclonal antibody produced in this study will enhance CMV monitoring and contribute to prevention of the spread of CMV infection which is spreading in yamCucumber mosaic virus (CMV) genus Cucumovirus was recently detected in yam in Ghana, Togo and Benin bringing to six the total number of countries reporting CMV infection in yam worldwide. Two serotypes of CMV are distinguished and a specific antibody against the yam isolate of CMV is currently not available. Rabbit polyclonal antibodies were produced against purified preparations of a yam isolate of CMV from Nigeria. The antibody titre was determined by Protein-A sandwich (PAS) enzymelinked immunosorbent assay (ELISA) and antigen-coated plate (ACP) ELISA. Antigen detection limit of the antibody was determined by PAS-ELISA using serial dilutions of infected sap. The CMV antiserum produced had a titre of 1:25,600 and 1:64,000 by PAS- and ACP-ELISA, respectively and a sap dilution end point of 1:160. The antibody detected homologous antigen in infected yam leaves from Ghana, Togo, Benin and Nigeria. The CMV polyclonal antibody produced in this study will enhance CMV monitoring and contribute to prevention of the spread of CMV infection which is spreading in ya

    Acoustic Test Characterization of Melamine Foam for Usage in NASA's Payload Fairing Acoustic Attenuation Systems

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    The external acoustic liftoff levels predicted for NASA's future heavy lift launch vehicles are expected to be significantly higher than the environment created by today's commercial launch vehicles. This creates a need to develop an improved acoustic attenuation system for future NASA payload fairings. NASA Glenn Research Center initiated an acoustic test series to characterize the acoustic performance of melamine foam, with and without various acoustic enhancements. This testing was denoted as NEMFAT, which stands for NESC Enhanced Melamine Foam Acoustic Test, and is the subject of this paper. Both absorption and transmission loss testing of numerous foam configurations were performed at the Riverbank Acoustical Laboratory in July 2013. The NEMFAT test data provides an initial acoustic characterization and database of melamine foam for NASA. Because of its acoustic performance and lighter mass relative to fiberglass blankets, melamine foam is being strongly considered for use in the acoustic attenuation systems of NASA's future launch vehicles

    3D geological models and their hydrogeological applications : supporting urban development : a case study in Glasgow-Clyde, UK

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    Urban planners and developers in some parts of the United Kingdom can now access geodata in an easy-to-retrieve and understandable format. 3D attributed geological framework models and associated GIS outputs, developed by the British Geological Survey (BGS), provide a predictive tool for planning site investigations for some of the UK's largest regeneration projects in the Thames and Clyde River catchments. Using the 3D models, planners can get a 3D preview of properties of the subsurface using virtual cross-section and borehole tools in visualisation software, allowing critical decisions to be made before any expensive site investigation takes place, and potentially saving time and money. 3D models can integrate artificial and superficial deposits and bedrock geology, and can be used for recognition of major resources (such as water, thermal and sand and gravel), for example in buried valleys, groundwater modelling and assessing impacts of underground mining. A preliminary groundwater recharge and flow model for a pilot area in Glasgow has been developed using the 3D geological models as a framework. This paper focuses on the River Clyde and the Glasgow conurbation, and the BGS's Clyde Urban Super-Project (CUSP) in particular, which supports major regeneration projects in and around the City of Glasgow in the West of Scotland

    Demonstration of the Zero-Crossing Phasemeter with a LISA Test-bed Interferometer

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    The Laser Interferometer Space Antenna (LISA) is being designed to detect and study in detail gravitational waves from sources throughout the Universe such as massive black hole binaries. The conceptual formulation of the LISA space-borne gravitational wave detector is now well developed. The interferometric measurements between the sciencecraft remain one of the most important technological and scientific design areas for the mission. Our work has concentrated on developing the interferometric technologies to create a LISA-like optical signal and to measure the phase of that signal using commercially available instruments. One of the most important goals of this research is to demonstrate the LISA phase timing and phase reconstruction for a LISA-like fringe signal, in the case of a high fringe rate and a low signal level. We present current results of a test-bed interferometer designed to produce an optical LISA-like fringe signal previously discussed in the literature.Comment: find minor corrections in the CQG versio

    Production of Polyclonal Antibody Against an Isolate of Yam-infecting Badnavirus from Nigeria

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    Integrated viral sequences and high sequence variability among badnaviruses complicates the development of specific reliable molecular detection tests for yam-infecting badnaviruses. Thus Serological techniques are of notable importance for routine testing and monitoring of these viruses. The major limiting factor to the use of serological techniques is the limited availability of antibodies. Rabbit polyclonal antibody was produced against a purified preparation of a yam-infecting badnavirus from Nigeria. Antibody titre was determined by Protein-A sandwich (PAS) enzyme-linked immunosorbent assay (ELISA). The antibody produced had a titre of 1:1280 in PAS-ELISA and detected yam-infecting badnaviruses in infected yam leaves from Nigeria, Ghana, Benin and Togo. The suitability of the antibody for use in immunocapture polymerase chain reaction (IC-PCR) was evaluated. The antibody successfully trapped both Dioscorea alata bacilliform virus (DaBV) and Dioscorea sansibarensis bacilliform virus (DsBV) for IC-PCR detection. The antibody produced in this study will enhance certification of yam planting materials across West Africa and also facilitate the safe international movement of yam germplasm
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