1,606 research outputs found

    Elemental chemostratigraphy of the Three Forks Formation, Williston Basin, North Dakota

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    The Three Forks Formation of the Williston Basin in northwestern North Dakota is an Upper Devonian stratigraphic unit unconformably overlain by the Bakken Formation. It consists principally of dolostone, shale and anhydrite. The Three Forks is a productive tight oil resource play, which in recent years has been increasingly targeted and developed as part of the unconventional Bakken Petroleum System. Core analysis via energy dispersive x-ray fluorescence (ED-XRF) is a non-destructive, high-resolution chemostratigraphic data collection method that has been used here to produce concentration logs which reflect both lithologic heterogeneity and paleoredox conditions for the Three Forks Formation. These geochemical analyses are compared with detailed core descriptions, lithofacies identifications and subsurface maps generated on the basis of tops picked from wireline logs. Such comparisons show that every major stratigraphic surface within the Three Forks Formation is discernable on the elemental chemostratigraphic curves produced in this study. The elemental concentration logs are further used to discuss chemostratigraphic ā€œpackagesā€ which are made up of consistently observed, correlatable trends in elemental geochemistry

    Prosomal-width-to-weight relationships in American horseshoe crabs (Limulus polyphemus): examining conversion factors used to estimate landings

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    Horseshoe crabs (Limulus polyphemus) are valued by many stakeholders, including the commercial fishing industry, biomedical companies, and environmental interest groups. We designed a study to test the accuracy of the conversion factors that were used by NOAA Fisheries and state agencies to estimate horseshoe crab landings before mandatory reporting that began in 1998. Our results indicate that the NOAA Fisheries conversion factor consistently overestimates the weight of male horseshoe crabs, particularly those from New England populations. Because of the inaccuracy of this and other conversion factors, states are now mandated to report the number (not biomass) and sex of landed horseshoe crabs. However, accurate estimates of biomass are still necessary for use in prediction models that are being developed to better manage the horseshoe crab fishery. We recommend that managers use the conversion factors presented in this study to convert current landing data from numbers to biomass of harvested horseshoe crabs for future assessments

    Impairment of the CD8+ T cell response in lungs following infection with human respiratory syncytial virus is specific to the anatomical site rather than the virus, antigen, or route of infection

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    <p>Abstract</p> <p>Background</p> <p>A subset of the virus-specific CD8+ cytotoxic T lymphocytes (CTL) isolated from the lungs of mice infected with human respiratory syncytial virus (RSV) is impaired in the ability to secrete interferon Ī³ (IFNĪ³), a measure of functionality. It was suggested that the impairment specifically suppressed the host cellular immune response, a finding that could help explain the ability of RSV to re-infect throughout life.</p> <p>Results</p> <p>To determine whether this effect is dependent on the virus, the route of infection, or the type of infection (respiratory, disseminated, or localized dermal), we compared the CTL responses in mice following intranasal (IN) infection with RSV or influenza virus or IN or intradermal (ID) infection with vaccinia virus expressing an RSV CTL antigen. The impairment was observed in the lungs after IN infection with RSV, influenza or vaccinia virus, and after a localized ID infection with vaccinia virus. In contrast, we observed a much higher percentage of IFNĪ³ secreting CD8+ lymphocytes in the spleens of infected mice in every case.</p> <p>Conclusion</p> <p>The decreased functionality of CD8+ CTL is specific to the lungs and is not dependent on the specific virus, viral antigen, or route of infection.</p

    The neurovirulence and neuroinvasiveness of chimeric tick-borne encephalitis/dengue virus can be attenuated by introducing defined mutations into the envelope and NS5 protein genes and the 3ā€² non-coding region of the genome

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    AbstractTick-borne encephalitis (TBE) is a severe disease affecting thousands of people throughout Eurasia. Despite the use of formalin-inactivated vaccines in endemic areas, an increasing incidence of TBE emphasizes the need for an alternative vaccine that will induce a more durable immunity against TBE virus (TBEV). The chimeric attenuated virus vaccine candidate containing the structural protein genes of TBEV on a dengue virus genetic background (TBEV/DEN4) retains a high level of neurovirulence in both mice and monkeys. Therefore, attenuating mutations were introduced into the envelope (E315) and NS5 (NS5654,655) proteins, and into the 3ā€² non-coding region (Ī”30) of TBEV/DEN4. The variant that contained all three mutations (vĪ”30/E315/NS5654,655) was significantly attenuated for neuroinvasiveness and neurovirulence and displayed a reduced level of replication and virus-induced histopathology in the brains of mice. The high level of safety in the central nervous system indicates that vĪ”30/E315/NS5654,655 should be further evaluated as a TBEV vaccine

    Elliptical-core two mode fiber sensors and devices incorporating photoinduced refractive index gratings

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    Results of experiments performed using germanium-doped, elliptical core, two-mode optical fibers whose sensitivity to strain was spatially varied through the use of chirped, refractive-index gratings permanently induced into the core using Argon-ion laser light are presented. This type of distributed sensor falls into the class of eighted-fiber sensors which, through a variety of means, weight the strain sensitivity of a fiber according to a specified spatial profile. We describe results of a weighted-fiber vibration mode filter which successfully enhances the particular vibration mode whose spatial profile corresponds to the profile of the grating chirp. We report on the high temperature survivability of such grating-based sensors and discuss the possibility of multiplexing more than one sensor within a single fiber

    Genome sequence analysis of La Crosse virus and in vitro and in vivo phenotypes

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    <p>Abstract</p> <p>Background</p> <p>La Crosse virus (LACV), family <it>Bunyaviridae</it>, is a mosquito-borne virus recognized as a major cause of pediatric encephalitis in North America with 70ā€“130 symptomatic cases each year. The virus was first identified as a human pathogen in 1960 after its isolation from a 4 year-old girl who suffered encephalitis and died in La Crosse, Wisconsin. The majority of LACV infections are mild and never reported, however, serologic studies estimate infection rates of 10ā€“30/100,000 in endemic areas.</p> <p>Results</p> <p>In the present study, sequence analysis of the complete LACV genomes of low-passage LACV/human/1960, LACV/mosquito/1978, and LACV/human/1978 strains and of biologically cloned derivatives of each strain, indicates that circulating LACVs are genetically stable over time and geographic distance with 99.6ā€“100%, 98.9ā€“100%, 97.8ā€“99.6%, and 99.2ā€“99.7% amino acid identity for N, NsS, M polyprotein, and L proteins respectively. We identified 5 amino acid differences in the RNA polymerase and 4 nucleotide differences in the non-coding region of the L segment specific to the human virus isolates, which may result in altered disease outcomes.</p> <p>Conclusion</p> <p>All three wild type viruses had similar <it>in vitro </it>growth kinetics and phenotypes in mosquito C6/36 and Vero cells, and similar levels of neurovirulence and neuroinvasiveness in Swiss Webster mice. The biologically cloned derivative of LACV/human/1960 was significantly less neuroinvasive than its uncloned parent and differed in sequence at one amino acid position in the G<sub>N </sub>glycoprotein, identifying this residue as an attenuating mutation.</p
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