Isolation-reared mallards (Anas platyrhynchos) were placed on ponds in turkey-rearing areas in Minnesota, and their cloacae were periodically swabbed to attempt isolating virus from embryonated chicken eggs. Nearby turkeys were sampled by taking cloacal and tracheal swabs as well as blood samples. Hemagglutinating viruses were identified at the National Veterinary Services Laboratory, U.S. Department of Agriculture, Ames, Iowa. During this two-year study, the weekly influenza virus-isolation rate from ducks varied from 0 to 24.4%. A total of 213 influenza viruses were isolated from the ducks. Twenty-six influenza virus subtypes were detected. Ninety-seven flocks of turkeys were diagnosed as having influenza by virus isolation and/or serology. Eight influenza virus subtypes were involved in the turkey outbreaks, and seven of these were also detected in the ducks and/or other avian species. The weekly infection rate of the sentinel ducks correlated directly with observations of wild ducks at the monitoring sites. Influenza virus was isolated from water samples collected near the sentinel duck sites during the study.
Influenza A virus isolates from ring-billed, Franklin, blackback, and herring gulls in the United States possess a hemagglutinin (HA) distinct from the 12 reference HA subtypes. Serological assays (hemagglutination inhibition and double-immunodiffusion) with specific antisera to reference strains and to a representative gull isolate showed that the HA of the gull virus was not antigenically related to that of any known subtype. The gull virus did not replicate in ducks or chickens but did replicate in ferrets. Comparison of the nucleotide sequences (and deduced amino acid sequences) of the 3' 20% of the HA genes of these viruses indicates that the gull viruses represent a genetically distinct group. We propose that this HA, which has been detected only in gull isolates thus far, be called the H13 subtype.
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AbstractSteel catenary risers (SCR) have been an attractive choice for recent deep-water field developments. However, design of SCRs for harsh environment is a great challenge, especially from large motion host platforms such as semi-submersible platforms. The key driver for the design of SCR in harsh environment is the fatigue near hang-off and at touch down point.This paper describes the concept of weight optimized SCR design for deep water harsh environment fulfilling both strength and fatigue requirements. The concepts incorporate presently available materials and technology. For the fatigue critical cross-sections, some qualified cost-effective and easily installable solutions are proposed. These proposed concepts are demonstrated through case studies of a few common riser sizes for such deep water field development with large vessel motions.
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SUMMARY The isolation of avian influenza virus from chickens is reported for the second time in the United States since the fowl plague outbreak in 1929. The Hav6Nl influenza A virus was identified by virus isolation and/or serological techniques from three flocks of commercial Leghorn hens on a single farm in central Minnesota.A fourth house on the same farm was unaffected. Mortality was moderate, whereas egg production declined markedly.
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