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  • AIRCRAFT STABILITY AND CONTROL  (7)
  • Astrophysics  (4)
  • Earth Resources and Remote Sensing  (2)
  • flagella  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Molecular analysis of the alpha and beta dynein genes of Chlamydomonas reinhardtii (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 435-445 
    Details
    ISSN: 0886-1544
    Keywords: flagella ; dynein heavy chains ; flagellar ATPase ; sequence homology ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We previously cloned portions of the alpha and beta dynein heavy chain genes of Chlamydomonas reinhardtii by screening a genomic expression library with monoclonal antibodies (Williams et al.: Journal of Cell Biology 103:1-11, 1986). Here we provide further evidence of the identity of these clones and describe the selection of adjacent regions from a large insert genomic library. Southern blots indicate that only a single copy of each gene is present in the Chlamydomonas genome, while Northern blots show that both heavy chains are encoded by 13.5 kilobase mRNAs and that the corresponding transcription units each span approximately 20 kilobase-pairs of genomic DNA. No similarities were detected between restriction maps of the alpha and beta dynein genes, but extensive regions of sequence similarity were identified by the cross-hybridization of cloned gene fragments.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970140313
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Protein-protein interactions in the 18S ATPase of Chlamydomonas outer dynein arms (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 510-520 
    Details
    ISSN: 0886-1544
    Keywords: flagella ; motility ; dynein substructure ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When outer-row dynein arms are extracted from Chlamydomonas flagellar axonemes, they dissociate into two ATPase complexes with sedimentation coefficients of 12S and 18S. We immunized mice with 18S dynein and generated a library of monoclonal antibodies against the polypeptides in this complex. Antibodies were selected which specifically recognize the 18S α- and β-heavy chains and the 83,000-dalton and 70,000-dalton intermediate chains. These antibodies were isolated and characterized for their ability to recognize determinants on both denatured antigens and native 18S dynein; 18S dynein was dissociated in stepwise fashion into smaller aggregates with ionic and nonionic detergents and the resulting subcomplexes were isolated by precipitation with specific monoclonal antibodies. The smallest aggregates isolated were heterodimers between the α-chain and a 16,000-dalton light chain and between the two intermediate chains. Additional close associations of the β-heavy chain with an 18,000-dalton light chain and 70,000-dalton intermediate chain, and a weaker interaction between the intermediate chain heterodimer and light chains of 21,000 daltons and 12,500 daltons, were also observed. We present a model of 18S dynein substructure based upon this information.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970060510
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    Paper (German National Licenses)
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  • 3
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    Effects of simulator motion and visual characteristics on rotorcraft handling qualities evaluations (1993)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The pilot's perceptions of aircraft handling qualities are influenced by a combination of the aircraft dynamics, the task, and the environment under which the evaluation is performed. When the evaluation is performed in a groundbased simulator, the characteristics of the simulation facility also come into play. Two studies were conducted on NASA Ames Research Center's Vertical Motion Simulator to determine the effects of simulator characteristics on perceived handling qualities. Most evaluations were conducted with a baseline set of rotorcraft dynamics, using a simple transfer-function model of an uncoupled helicopter, under different conditions of visual time delays and motion command washout filters. Differences in pilot opinion were found as the visual and motion parameters were changed, reflecting a change in the pilots' perceptions of handling qualities, rather than changes in the aircraft model itself. The results indicate a need for tailoring the motion washout dynamics to suit the task. Visual-delay data are inconclusive but suggest that it may be better to allow some time delay in the visual path to minimize the mismatch between visual and motion, rather than eliminate the visual delay entirely through lead compensation.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: NASA. Ames Research Center, Piloting Vertical Flight Aircraft: A Conference on Flying Qualities and Human Factors; p 341-359
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Simulation evaluation of the effects of time delay and motion on rotorcraft handling qualities (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A study aimed at determining the effects of simulator characteristics on perceived handling qualities is discussed. Evaluations were conducted with a baseline set of rotorcraft dynamics, using a simple transfer-function model of an uncoupled helicopter, under different conditions of visual and overall time delays. As the visual and motion parameters were changed, differences in pilot opinion were found reflecting a change in the pilots' perceptions of handling qualities, rather than changes in the aircraft model itself. It is concluded that it is necessary to tailor the motion washout dynamics to suit the task, with reduced washouts for precision maneuvering as compared to aggressive maneuvering. Visual-delay data suggest that it may be better to allow some time delay in the visual path to minimize the mismatch between visual and motion, rather than eliminate the visual delay entirely through lead compensation.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: AIAA PAPER 91-2892
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Effects of cockpit lateral stick characteristics on handling qualities and pilot dynamics (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: This report presents the results of analysis of cockpit lateral control feel-system studies. Variations in feel-system natural frequency, damping, and command sensing reference (force and position) were investigated, in combination with variations in the aircraft response characteristics. The primary data for the report were obtained from a flight investigation conducted with a variable-stability airplane, with additional information taken from other flight experiments and ground-based simulations for both airplanes and helicopters . The study consisted of analysis of handling qualities ratings and extraction of open-loop, pilot-vehicle describing functions from sum-of-sines tracking data, including, for a limited subset of these data, the development of pilot models. The study confirms the findings of other investigators that the effects on pilot opinion of cockpit feel-system dynamics are not equivalent to a comparable level of added time delay, and until a more comprehensive set of criteria are developed, it is recommended that feel-system dynamics be considered a delay-inducing element in the aircraft response. The best correlation with time-delay requirements was found when the feel-system dynamics were included in the delay measurements, regardless of the command reference. This is a radical departure from past approaches.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: NASA-CR-4443 , H-1769 , NAS 1.26:4443
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Simulation investigation of the effects of helicopter hovering dynamics on pilot performance (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A fixed base simulation has been performed to investigate the handling qualities requirements for the mid-term pitch response of a helicopter at hover and in low-speed flight. Pilot rating results from this simulation were compared with those from previous experiments to develop handling qualities limits on the frequency and damping of the oscillatory mode in the hovering cubic. Pilot performance data obtained during the experiment were used to confirm the pilot rating results. These data show the pilot performance to closely match that predicted by the theory of piloted control. A means of predicting pilot ratings from the open-loop aircraft dynamics is presented.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: AIAA PAPER 87-2533
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    A flight investigation of helicopter low-speed response requirements (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A flight experiment has been conducted using the Canadian National Aeronautical Establishment's variable-stability airborne simulator to define the dynamic response requirements for operations at hover and low speeds. Fourteen Attitude Command/Attitude Hold, Rate, and Rate Command/Attitude Hold configurations were evaluated by six pilots using both conventional controls and a four-axis integrated sidestick over a low-speed course consisting of precision hover, landing, sidestep, and dash/quickstop tasks. The results indicate that with conventional controls all three response-types were acceptable as long as their response bandwidth was sufficiently high, and higher bandwidths were required in roll than in pitch. With the four-axis sidestick, there was a preference for the Rate systems. The range of acceptable bandwidths was lower, and the spread in pilot ratings smaller, than were found in a similar ground-based simulation.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: AIAA PAPER 87-2285
    Format: text
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    NASA TECHNICAL REPORTS
  • 8
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    Calipso Observations of the Dependence of Homo- and Heterogeneous Ice Nucleation in Cirrus Clouds on Latitude, Season and Surface Condition (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-26
    Description: There are two fundamental mechanisms through which cirrus clouds form; homo- and heterogeneous ice nucleation (henceforth hom and het). The relative contribution of each mechanism to ice crystal production often determines the microphysical and radiative properties of a cirrus cloud. A new satellite remote sensing method is described in this study to estimate cirrus cloud ice particle number concentration and the relative contribution of hom and het to cirrus cloud formation as a function of altitude, latitude, season and surface type (e.g. land vs. ocean). This method uses co-located observations from the Infrared Imaging Radiometer (IIR) and from the CALIOP (Cloud and Aerosol Lidar with Orthogonal Polarization) lidar aboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) polar orbiting satellite, employing IIR channels at 10.6 m and 12.05 m. The method is applied here to single-layered clouds of visible optical depth between about 0.3 and 3. Two years of Version 3 data have been analyzed for the years 2008 and 2013, with each season characterized in terms of 532 nm cirrus cloud centroid altitude and temperature, the cirrus cloud ice particle number concentration, effective diameter, layer-average ice water content and visible optical depth. Using a conservative criterion for hom cirrus, on average, the sampled cirrus clouds formed through hom occur about 43% of the time in the Arctic and 50% of the time in the Antarctic, and during winter at mid-latitudes in the Northern Hemisphere, hom cirrus occur 37% of the time. Elsewhere (and during other seasons in the Northern Hemisphere mid-latitudes), this hom cirrus fraction is lower. Processes that could potentially explain these observations are discussed, as well as the potential relevancy of these results to ice nucleation studies, climate modeling and jet-stream dynamics.
    Keywords: Earth Resources and Remote Sensing
    Type: NF1676L-26187
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Radar Observations of Asteroid 1620 Geographos (1996)
    In:  Other Sources
    Details
    Publication Date: 2019-08-16
    Description: Goldstone radar observations of Geographos from August 28 through September 2, 1994 yield over 400 delay-Doppler images whose linear spatial resolutions range from approx. 75 to approx. 151 in, and 138 pairs of dual-polarization (OC, SC) spectra with one-dimensional resolution of 103 m. Each data type provides thorough rotational coverage. The images contain an intrinsic north/south ambiguity, but the equatorial view allows accurate determination of the shape of the radar-facing part of the asteroid's pole-on silhouette at any rotation phase. Sums of co-registered images that cover nearly a full rotation have defined the extremely elongated shape of that silhouette. Here we present individual images and co-registered sums over approx. 30 deg of rotation phase that show the silhouette's structural characteristics in finer detail and also reveal numerous contrast features "inside" the silhouette. Those features include several candidate craters as well as indications of other sorts of large-scale topographic relief, including a prominent central indentation. Protuberances at the asteroid's ends may be related to the pattern of ejecta removal and deposition caused by the asteroid's gravity field. The asteroid's surface is homogeneous and displays only modest roughness at centimeter-to-meter scales. Our estimates of radar cross section and the currently available constraints on the asteroid's dimensions are consistent with a near-surface bulk density between 2 and 3 g/cu cm. The delay-Doppler trajectory of Geographos' center of mass has been determined to about 200 m on August 28 and to about 100 m on August 31, an improvement of two orders of magnitude over pre-observation ephemerides.
    Keywords: Astrophysics
    Type: Rept-0071 , ICARUS (ISSN 0019-1035); 121; 46-66
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    NASA TECHNICAL REPORTS
  • 10
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    Flight investigation of helicopter low-speed response requirements (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 12; 623-630
    Format: text
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    NASA TECHNICAL REPORTS
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