30,235 research outputs found

    Bioengineering Lantibiotics for Therapeutic Success

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    peer-reviewedSeveral examples of highly modified antimicrobial peptides have been described. While many such peptides are non-ribosomally synthesized, ribosomally synthesized equivalents are being discovered with increased frequency. Of the latter group, the lantibiotics continue to attract most attention. In the present review, we discuss the implementation of in vivo and in vitro engineering systems to alter, and even enhance, the antimicrobial activity, antibacterial spectrum and physico-chemical properties, including heat stability, solubility, diffusion and protease resistance, of these compounds. Additionally, we discuss the potential applications of these lantibiotics for use as therapeutics.DF,CH,PC,RR are supported by the Irish Government under the National Development Plan, through a Science Foundation Ireland (SFI) Technology and Innovation Development Award (TIDA14/TIDA/2286) to DF, a SFI Investigator awards to CH and RR (10/IN.1/B3027),SFI-PIfunding(11/PI/1137) to PDC and the Alimentary Pharmabiotic Centre under Grant Number SFI/12/RC/2273

    Classification and reduction of pilot error

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    Human error is a primary or contributing factor in about two-thirds of commercial aviation accidents worldwide. With the ultimate goal of reducing pilot error accidents, this contract effort is aimed at understanding the factors underlying error events and reducing the probability of certain types of errors by modifying underlying factors such as flight deck design and procedures. A review of the literature relevant to error classification was conducted. Classification includes categorizing types of errors, the information processing mechanisms and factors underlying them, and identifying factor-mechanism-error relationships. The classification scheme developed by Jens Rasmussen was adopted because it provided a comprehensive yet basic error classification shell or structure that could easily accommodate addition of details on domain-specific factors. For these purposes, factors specific to the aviation environment were incorporated. Hypotheses concerning the relationship of a small number of underlying factors, information processing mechanisms, and error types types identified in the classification scheme were formulated. ASRS data were reviewed and a simulation experiment was performed to evaluate and quantify the hypotheses

    GeoSay: A Geometric Saliency for Extracting Buildings in Remote Sensing Images

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    Automatic extraction of buildings in remote sensing images is an important but challenging task and finds many applications in different fields such as urban planning, navigation and so on. This paper addresses the problem of buildings extraction in very high-spatial-resolution (VHSR) remote sensing (RS) images, whose spatial resolution is often up to half meters and provides rich information about buildings. Based on the observation that buildings in VHSR-RS images are always more distinguishable in geometry than in texture or spectral domain, this paper proposes a geometric building index (GBI) for accurate building extraction, by computing the geometric saliency from VHSR-RS images. More precisely, given an image, the geometric saliency is derived from a mid-level geometric representations based on meaningful junctions that can locally describe geometrical structures of images. The resulting GBI is finally measured by integrating the derived geometric saliency of buildings. Experiments on three public and commonly used datasets demonstrate that the proposed GBI achieves the state-of-the-art performance and shows impressive generalization capability. Additionally, GBI preserves both the exact position and accurate shape of single buildings compared to existing methods

    Identifying thermogenic and microbial methane in deep water Gulf of Mexico Reservoirs

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    The Gulf of Mexico (GOM) produces 5% of total U.S. dry gas production (USEIA, 2016). Despite this, the proportion of microbial and thermogenic methane in discovered and producing fields from this area is still not well understood. Understanding the relative contributions of these sources in subsurface environments is important to understanding how and where economically substantial amounts of methane form. In addition, this information will help identify sources of environmental emissions of hydrocarbons to the atmosphere. We apply stable isotopes including methane clumped-isotope measurements to solution and associated gases from several producing fields in the U.S. Gulf of Mexico to estimate the proportions, properties and origins of microbial and thermogenic endmembers. Clumped isotopes of methane are unique indicators of whether methane is at thermodynamic isotopic equilibrium or affected by kinetic processes. The clumped methane thermometer can provide insights into formation temperatures and/or into kinetic processes such as microbial methanogenesis, early catagenetic processes, mixing, combinatorial processes, and diffusion. In this data set, we find that some fluids have clumped isotope methane apparent temperatures consistent with the methane component being produced solely by the thermogenic breakdown of larger organic molecules at substantially greater temperatures than those reached in shallow reservoirs. A portion of these reservoirs with hot clumped isotope methane temperatures are consistent with exhibiting a kinetic isotope effect. Other reservoirs have clumped isotope methane apparent temperatures, and other isotopic and molecular proportions, consistent with mixtures of microbial and thermogenic methane. We show that in certain cases the evidence is most consistent with formation of the microbial methane in the current reservoir. However, in other cases the methane is produced at significantly shallower depths and is then transported to greater depths as a result of post generation burial of methane bearing sedimentary sequences to the current reservoir conditions. For the first time, we show that methane of an unambiguously purely microbial origin (i.e. those that do not contain obvious contributions of thermogenic methane) is dominantly generated at temperatures less than 60 °C, despite burial to greater depths. This finding suggests that, while microorganisms are able to generate methane at temperatures up to 105 °C under laboratory conditions (Brock, 1985), in the Gulf of Mexico, microbial methane is dominantly produced in the 20–60 °C window
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