9,453 research outputs found

    Invasion of the shovelnose ray (Rhinobatos typus) by Neoheterocotyle rhinobatidis and Merizocotyle icopae (Monogenea : Monocotylidae)

    Get PDF
    This study examined the route of infection by free-swimming larvae of 2 monocotylid monogeneans that inhabit the gills (Neoheterocotyle rhinobatidis) and the nasal tissue (Merizocotyle icopae) of the shovelnose ray, Rhinobatos typus, from Heron Island on the Great Barrier Reef, Australia. Larvae of N. rhinobatidis and M. icopae attached directly to the gills and the nasal tissue of the ray, respectively, and did not first settle on the skin. Initial development of the post-oncomiracidium of N. rhinobatidis was rapid and hamuli formed between 6 and 24 h p.i. at a mean temperature of 26 °C. However, growth then slowed markedly and was variable; only 2 fully mature individuals were found 20 days p.i. at a mean temperature of 24·5 °C. Development of M. icopae was slow and variable throughout; hamuli did not appear until 10 days p.i. and no mature individuals were obtained even 22 days p.i. at a mean temperature of 24·5 °C. No character could be found as an indicator of parasite age for N. rhinobatidis or M. icopae due to the high variability in development in both species.L. A. Chisholm and I. D. Whittingto

    Preliminary flight evaluation of an engine performance optimization algorithm

    Get PDF
    A performance seeking control (PSC) algorithm has undergone initial flight test evaluation in subsonic operation of a PW 1128 engined F-15. This algorithm is designed to optimize the quasi-steady performance of an engine for three primary modes: (1) minimum fuel consumption; (2) minimum fan turbine inlet temperature (FTIT); and (3) maximum thrust. The flight test results have verified a thrust specific fuel consumption reduction of 1 pct., up to 100 R decreases in FTIT, and increases of as much as 12 pct. in maximum thrust. PSC technology promises to be of value in next generation tactical and transport aircraft

    Development and flight test of a helicopter, X-band, portable precision landing system concept

    Get PDF
    A beacon landing system (BLS) is being developed and flight tested as a part of NASA's Rotorcraft All-Weather Operations Research Program. The system is based on state-of-of-the-art X-band radar technology and digital processing techniques. The bLS airborne hardware consists of an X-band receiver and a small micropreocessor, installed in conjunction wht the aircraft instrument landing system (ILS) receiver. The microprocessor analyzes the X-band, BLS pulses and outputs ILS-compatible localizer and glide slope signals. Range information is obtained using an on-board weather/mapping radar in conjunction with the BLS. The ground station is an inexpensive, portable unit; it weighs less than 70 lb and can be quickly deployed at a landing site. Results from the flight-test program show that the BLS has a significant potential for providing rotorcaraft with low-cost, precision instrument approach capability in remote areas

    Is attending a mental process?

    Get PDF
    The nature of attention has been the topic of a lively research programme in psychology for over a century. But there is widespread agreement that none of the theories on offer manage to fully capture the nature of attention. Recently, philosophers have become interested in the debate again after a prolonged period of neglect. This paper contributes to the project of explaining the nature of attention. It starts off by critically examining Christopher Mole’s prominent “adverbial” account of attention, which traces the failure of extant psychological theories to their assumption that attending is a kind of process. It then defends an alternative, process-based view of the metaphysics of attention, on which attention is understood as an activity and not, as psychologists seem to implicitly assume, an accomplishment. The entrenched distinction between accomplishments and activities is shown to shed new light on the metaphysics of attention. It also provides a novel diagnosis of the empirical state of play

    A preliminary phylogenetic analysis of the Capsalidae (Platyhelminthes : Monogenea : Monopisthocotylea) inferred from large subunit rDNA sequences

    Get PDF
    Phylogenetic relationships within the Capsalidae (Monogenea) were examined using large subunit ribosomal DNA sequences from 17 capsalid species (representing 7 genera, 5 subfamilies), 2 outgroup taxa (Monocotylidae) plus Udonella caligorum (Udonellidae). Trees were constructed using maximum likelihood, minimum evolution and maximum parsimony algorithms. An initial tree, generated from sequences 315 bases long, suggests that Capsalinae, Encotyllabinae, Entobdellinae and Trochopodinae are monophyletic, but that Benedeniinae is paraphyletic. Analyses indicate that Neobenedenia, currently in the Benedeniinae, should perhaps be placed in a separate subfamily. An additional analysis was made which omitted 3 capsalid taxa (for which only short sequences were available) and all outgroup taxa because of alignment difficulties. Sequence length increased to 693 bases and good branch support was achieved. The Benedeniinae was again paraphyletic. Higher-level classification of the Capsalidae, evolution of the Entobdellinae and issues of species identity in Neobenedenia are discussed.I. D. Whittington, M. R. Deveney, J. A. T. Morgan, L. A. Chisholm and R. D. Adlar

    Sound propagation over uneven ground and irregular topography

    Get PDF
    The acoustic impedance of the surface coverings used in the laboratory experiments on sound diffraction by topographical ridges was determined. The model, which was developed, takes into account full wave effects and the possibility of surface waves and predicts the sound pressure level at the receiver location relative to what would be expected if the flat surface were not present. The sound pressure level can be regarded as a function of frequency, sound speed in air, heights of source and receiver, and horizontal distance from source to receiver, as well as the real and imaginary parts of the surface impedance

    Listening to Fathers of Sons with Duchenne Muscular Dystrophy

    Get PDF
    Duchenne Muscular Dystrophy (DMD) affects the entire family, however, most studies concern maternal\ud adjustment with fathers’ adjustment largely overlooked. To investigate experiences of fathers\ud of sons with Duchenne Muscular Dystrophy (DMD) interviews were held with 15 fathers of a son with\ud DMD, from across the UK. 55 fathers from an associated study also provided written accounts.\ud Grounded theory methodology was used to evaluate the data. Four key themes emerged: 1) loss and\ud acceptance; 2) support versus isolation; 3) fight for resources and 4) race against time. Fathers described the impact of emotional/behavioural factors, which were not routinely addressed by professionals.\ud Findings emphasise importance of person-centred care, indicating how needs could be met,\ud from fathers’ perspectives

    The InfraRed Imaging Spectrograph (IRIS) for TMT: photometric precision and ghost analysis

    Get PDF
    The InfraRed Imaging Spectrograph (IRIS) is a first-light instrument for the Thirty Meter Telescope (TMT) that will be used to sample the corrected adaptive optics field by NFIRAOS with a near-infrared (0.8 - 2.4 μ\mum) imaging camera and Integral Field Spectrograph (IFS). In order to understand the science case specifications of the IRIS instrument, we use the IRIS data simulator to characterize photometric precision and accuracy of the IRIS imager. We present the results of investigation into the effects of potential ghosting in the IRIS optical design. Each source in the IRIS imager field of view results in ghost images on the detector from IRIS's wedge filters, entrance window, and Atmospheric Dispersion Corrector (ADC) prism. We incorporated each of these ghosts into the IRIS simulator by simulating an appropriate magnitude point source at a specified pixel distance, and for the case of the extended ghosts redistributing flux evenly over the area specified by IRIS's optical design. We simulate the ghosting impact on the photometric capabilities, and found that ghosts generally contribute negligible effects on the flux counts for point sources except for extreme cases where ghosts coalign with a star of Δ\Deltam>>2 fainter than the ghost source. Lastly, we explore the photometric precision and accuracy for single sources and crowded field photometry on the IRIS imager.Comment: SPIE 2018, 14 pages, 14 figures, 4 tables, Proceedings of SPIE 10702-373, Ground-based and Airborne Instrumentation for Astronomy VII, 10702A7 (16 July 2018
    corecore