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  • 1
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    Ecological context influences epidemic size and parasite-driven evolution (2012)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2012-03-31
    Description: The occurrence and magnitude of disease outbreaks can strongly influence host evolution. In particular, when hosts face a resistance-fecundity trade-off, they might evolve increased resistance to infection during larger epidemics but increased susceptibility during smaller ones. We tested this theoretical prediction by using a zooplankton-yeast host-parasite system in which ecological factors determine epidemic size. Lakes with high productivity and low predation pressure had large yeast epidemics; during these outbreaks, hosts became more resistant to infection. However, with low productivity and high predation, epidemics remained small and hosts evolved increased susceptibility. Thus, by modulating disease outbreaks, ecological context (productivity and predation) shaped host evolution during epidemics. Consequently, anthropogenic alteration of productivity and predation might strongly influence both ecological and evolutionary outcomes of disease.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Duffy, Meghan A -- Ochs, Jessica Housley -- Penczykowski, Rachel M -- Civitello, David J -- Klausmeier, Christopher A -- Hall, Spencer R -- New York, N.Y. -- Science. 2012 Mar 30;335(6076):1636-8. doi: 10.1126/science.1215429.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Biology, Georgia Institute of Technology, Atlanta, GA 30332-0230, USA. duffy@gatech.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22461614" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Daphnia/*microbiology/*physiology ; *Ecosystem ; Female ; Fishes ; *Host-Pathogen Interactions ; Indiana ; *Lakes ; Male ; Metschnikowia/*pathogenicity ; Models, Biological ; Population Dynamics ; Predatory Behavior ; Reproduction ; Zooplankton/microbiology/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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    PAPER CURRENT
  • 2
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    Aircraft control surface failure detection and isolation using the OSGLR test (1986)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The performance of the orthogonal series generalized likelihood ratio (OSGLR) test in detecting and isolating commercial aircraft control surface and actuator failures is evaluated. A modification to incorporate age-weighting which significantly reduces the sensitivity of the algorithm to modeling errors is presented. The steady-state implementation of the algorithm based on a single linear model valid for a cruise flight condition is tested using a nonlinear aircraft simulation. A number of off-nominal no-failure flight conditions including maneuvers, nonzero flap deflections, different turbulence levels and steady winds were tested. Based on the no-failure decision functions produced by off-nominal flight conditions, the failure detection and isolation performance at the nominal flight condition was determined. The extension of the algorithm to a wider flight envelope by scheduling on dynamic pressure and flap deflection is examined. Based on this testing, the OSGLR algorithm should be capable of detecting control surface failures that would affect the safe operation of a commercial aircraft. Isolation may be difficult if there are several surfaces which produce similar effects on the aircraft. Extending the algorithm over the entire operating envelope of a commercial aircraft appears feasible.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: AIAA PAPER 86-2028
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    The application of the detection filter to aircraft control surface and actuator failure detection and isolation (1985)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The performance of the detection filter in detecting and isolating aircraft control surface and actuator failures is evaluated. The basic detection filter theory assumption of no direct input-output coupling is violated in this application due to the use of acceleration measurements for detecting and isolating failures. With this coupling, residuals produced by control surface failures may only be constrained to a known plane rather than to a single direction. A detection filter design with such planar failure signatures is presented, with the design issues briefly addressed. In addition, a modification to constrain the residual to a single known direction even with direct input-output coupling is also presented. Both the detection filter and the modification are tested using a nonlinear aircraft simulation. While no thresholds were selected, both filters demonstrated an ability to detect control surface and actuator failures. Failure isolation may be a problem if there are several control surfaces which produce similar effects on the aircraft. In addition, the detection filter was sensitive to wind turbulence and modeling errors.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: AIAA PAPER 85-1973 , Guidance, Navigation and Control Conference; Aug 19, 1985 - Aug 21, 1985; Snowmass, CO
    Format: text
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    NASA TECHNICAL REPORTS
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