Scale-model wave basin testing is often employed in the development and validation oflarge-scale offshore vessels and structures by the oil and gas, military, and marine industries. A basin-model test requires less time, resources, and risk than a full-scale test, while providing real and accurate data for numerical simulator validation. As the development of floating wind turbine technology progresses in order to capture the vast deepwater wind energy resource, it is clear that model testing will be essential for the economical and efficient advancement of this technology. However, the scale model testing of floating wind turbines requires accurate simulation of the wind and wave environments, structural flexibility, and wind turbine aerodynamics and thus requires a comprehensive scaling methodology. This paper presents a unified methodology for Froude scale model testing of floating wind turbines under combined wind and wave loading. First, an overview of the scaling relationships employed for the environment, floater, and wind turbine are presented. Aftemwd, a discussion is presented concerning suggested methods for manufacturing a high-quality, low-turbulence Froude scale wind environment in a wave basin to facilitate simultaneous application of wind and waves to the model. Subsequently, the difficulties of scaling the highly Reynolds number-dependent wind turbine aerodynamics is presented in addition to methods for tailoring the turbine and wind characteristics to best emulate the full-scale condition. Lastly, the scaling methodology is demonstrated using results from 1150th-scale floating wind turbine testing performed at the Maritime Research Institute Netherlands (MARIN) Offshore Basin. The model test campaign investigated the response of the 126 -m rotor diameter National Renewable Energy Lab (NREL) horizontal axis wind turbine atop three floating platforms: a tension-leg platform, a spar-buoy, and a semisubmersible. The results highlight the methodology's strengths and weaknesses for simulating full-scale global response of floating wind turbine systems.In order to establish a scaling methodology, a particular set of rules and constraints must be selected. The suggested scaling Journal of Offshore Mechanics and Arctic Engineering
Scale model wave basin testing is often employed in the development and validation of large scale offshore vessels and structures by the oil and gas, military and marine industries. A basin model test requires less time, resources and risk than a full scale test while providing real and accurate data for model validation. As the development of floating wind turbine technology progresses in order to capture the vast deepwater wind energy resource, it is clear that model testing will be essential for the economical and efficient advancement of this technology. However, the scale model testing of floating wind turbines requires one to accurately simulate the wind and wave environments, structural flexibility and wind turbine aerodynamics, and thus requires a comprehensive scaling methodology. This paper presents a unified methodology for Froude scale testing of floating wind turbines under combined wind and wave loading. First, an overview of the scaling relationships employed for the environment, floater and wind turbine are presented. Afterward, a discussion is presented concerning suggested methods for manufacturing a high-quality, low turbulence Froude scale wind environment in a wave basin to facilitate simultaneous application of wind and waves to the model. Subsequently, the difficulties of scaling the highly Reynolds number-dependent wind turbine aerodynamics is presented in addition to methods for tailoring the turbine and wind characteristics to best emulate the full scale condition. Lastly, the scaling methodology is demonstrated using results from 1/50th scale floating wind turbine testing performed at MARIN’s (Maritime Research Institute Netherlands) Offshore Basin which tested the 126 m rotor diameter NREL (National Renewable Energy Lab) horizontal axis wind turbine atop three floating platforms: a tension-leg platform, a spar-buoy and a semi-submersible. The results demonstrate the methodology’s ability to adequately simulate full scale global response of floating wind turbine systems.
Non-human primates (NHPs) for biomedical research are commonly infected with Shigella spp. that can cause acute dysentery or chronic episodic diarrhea. These animals are often prophylactically and clinically treated with quinolone antibiotics to eradicate these possible infections. However, chromosomally- and plasmid-mediated antibiotic resistance has become an emerging concern for species in the family Enterobacteriaceae. In this study, five individual isolates of multi-drug resistant Shigella flexneri were isolated from the feces of three macaques. Antibiotic susceptibility testing confirmed resistance or decreased susceptibility to ampicillin, amoxicillin-clavulanic acid, cephalosporins, gentamicin, tetracycline, ciprofloxacin, enrofloxacin, levofloxacin, and nalidixic acid. S. flexneri isolates were susceptible to trimethoprim-sulfamethoxazole, and this drug was used to eradicate infection in two of the macaques. Plasmid DNA from all isolates was positive for the plasmid-encoded quinolone resistance gene qnrS, but not qnrA and qnrB. Conjugation and transformation of plasmid DNA from several S. flexneri isolates into antibiotic-susceptible Escherichia coli strains conferred the recipients with resistance or decreased susceptibility to quinolones and beta-lactams. Genome sequencing of two representative S. flexneri isolates identified the qnrS gene on a plasmid-like contig. These contigs showed >99% homology to plasmid sequences previously characterized from quinolone-resistant Shigella flexneri 2a and Salmonella enterica strains. Other antibiotic resistance genes and virulence factor genes were also identified in chromosome and plasmid sequences in these genomes. The findings from this study indicate macaques harbor pathogenic S. flexneri strains with chromosomally- and plasmid-encoded antibiotic resistance genes. To our knowledge, this is the first report of plasmid-mediated quinolone resistance in S. flexneri isolated from NHPs and warrants isolation and antibiotic testing of enteric pathogens before treating macaques with quinolones prophylactically or therapeutically.
In select Helicobacter pylori-infected populations with low gastric cancer, nematode coinfections are common and both helicobacter gastritis and filariasis are modeled in gerbils. We evaluated gastritis, worm counts, tissue cytokine gene expression levels and Th1/Th2-associated antibody responses in H. pylori and Brugia pahangi mono- and coinfected gerbils. H. pylori-associated gastritis indices were significantly lower 21 weeks post-infection in coinfected gerbils (p ≤ 0.05) and were inversely proportional to worm counts (r2 = −0.62, p < 0.003). Additionally, IFN-γ, IL-1β, CXCL1, IL-4 and IL-10 mRNA levels in the gastric antrum reflected a significant host response to gastric H. pylori and as well as systemic filariasis (p ≤ 0.05). Despite increasing worm burden (p < 0.05), gastritis progressed in coinfected gerbils (p < 0.03) becoming equivalent to H. pylori-infected gerbils at 42 weeks (p = 0.7). Pro- and anti-inflammatory mediator mRNA levels were notably downregulated in B. pahangi infected gerbils below uninfected control values, suggesting hyporesponsiveness to B. pahangi. Consistent with an increasing Th1 response to H. pylori, IgG2a (p < 0.01), IL-1β (p = 0.04) and CXCL1 (p = 0.006) responses significantly increased and IL-4 (p = 0.05) and IL-10 (p = 0.04) were decreased in coinfected gerbils at 42 weeks. Initial systemic responses to B. pahangi resulted in attenuated gastritis in coinfected gerbils, but subsequent filarid-associated hyporesponsiveness appears to have promoted H. pylori gastritis.
Twenty-five (27 %) of 92 clinically normal macaques were found to have b-haemolytic Escherichia coli isolated from their faeces. Five of six isolates chosen for further characterization had multiple antibiotic resistance and were PCR-positive for cytotoxic necrotizing factor 1 (cnf1) with a demonstrated cytopathic effect in vitro. By repetitive element sequence-based PCR genotyping, genetic similarity was established for selected isolates. We believe this to be the first report of E. coli strains producing CNF1 in non-human primates. INTRODUCTIONEscherichia coli strains that produce cytotoxic necrotizing factors (CNFs) belong to the pathotype necrotoxigenic E. coli (NTEC) and are associated with intestinal and extraintestinal infections in both humans and animals (Kaper et al., 2004). The majority of toxin-producing isolates produce either the chromosomally encoded CNF1 (Falbo et al., 1993) or the plasmid-encoded CNF2 (Oswald et al., 1989); more recently, a third type has been isolated from sheep and goats and named CNF3 (Orden et al., 2007). CNF1 is a 115 kDa protein with lethal and necrotizing activity in vivo. In vitro, affected cells undergo multinucleation and membrane ruffling and form focal adhesions and actin stress fibres. The mechanism involves activation of Rho GTPases, a family of molecular switches with multiple cellular functions, resulting in reorganization of the actin cytoskeleton. CNF1 shares a pathogenicity island with a-haemolysin and P fimbriae . CNF1-producing strains most notably cause urinary tract infections in humans. These strains have also been isolated from healthy and diseased animal species. The list includes weaned pigs (Tó th et al., 2000) and dogs (Starcic et al., 2002) with diarrhoea; cats (Féria et al., 2001) and dogs (Johnson et al., 2003;Siqueira et al., 2009;Yuri et al., 1998) with urinary tract infections; ferrets with diarrhoea and extra-intestinal infections (Marini et al., 2004); and birds and mink with suspected colibacillosis (RodriguezSiek et al., 2005) and colisepticaemia (Tibbetts et al., 2003). NTEC-2 strains, although commonly reported in ruminants , have also been reported in a very small percentage of human faecal E. coli isolates (Kadhum et al., 2008). The objective of this study was to evaluate the presence of specific virulence genes and toxin activity in several b-haemolytic E. coli isolates cultured from a macaque colony used for neurobiology research. METHODSAnimals. Macaques (Macaca mulatta and Macaca fascicularis) received from three US-based vendors in 2005-2006 received physical examinations and routine diagnostic evaluations during quarantine and at quarterly intervals. Animals were routinely pair-housed and maintained in an animal facility accredited by the Association for Assessment and Accreditation of Laboratory Animal Care International. They were fed specified amounts of primate chow (Purina Lab Diet 5038) twice a day and provided with water ad libitum. Housing conditions were maintained at 20-22 uC, 30-70 % humidity, 10-15 non-recirculated ai...
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