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  • AERODYNAMICS  (448)
  • Life and Medical Sciences  (210)
  • GENERAL
  • 1975-1979  (618)
  • 1955-1959  (71)
  • 1
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    Aerodynamic characteristics in ground proximity (1976)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Results from recent investigations in the Langley V/STOL tunnel of an externally blown flap and an upper surface blown flap configuration in ground proximity are presented. Comparisons of longitudinal aerodynamic characteristics indicate that in ground proximity, drag is reduced for both configurations, but changes in lift are configuration dependent. Steady state analyses of the landing approach indicate an increase in flight path angle for both configurations in ground proximity because of the drag reduction. Dynamic analyses with a fixed-base simulator indicate that the resultant flight path during landing approach is dependent on the initial flight path angle and the control technique used.
    Keywords: AERODYNAMICS
    Type: Powered-Lift Aerodyn. and Acoustics; p 145-158
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Steady and unsteady transonic flow (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An investigation of the transonic flow over a circular arc airfoil was conducted to obtain basic information for turbulence modeling of shock-induced separated flows and to verify numerical computer codes which are being developed to simulate such flows. The investigation included the employment of a laser velocimeter to obtain data concerning the mean velocity, the shear stress, and the turbulent kinetic energy profiles in the flowfield downstream of the airfoil midchord where the flow features are more complex. Depending on the free-stream Mach number, the flowfield developed was either steady with shock-wave-induced separation extending from the foot of the shock wave to beyond the trailing edge or unsteady with a periodic motion also undergoing shock-induced separation. The experimental data were compared with the results of numerical simulations in which a computer code was employed that solved the time-dependent Reynolds' averaged compressible Navier-Stokes equations.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 78-160 , Aerospace Sciences Meeting; Jan 16, 1978 - Jan 18, 1978; Huntsville, AL
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    An experimental and computational investigation of the flow field about a transonic airfoil in supercritical flow with turbulent boundary-layer separation (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A combined experimental and computational research program for testing and guiding turbulence modeling within regions of separation induced by shock waves incident on turbulent boundary layers is described. Specifically, studies are made of the separated flow over the rear portion of an 18%-thick circular-arc airfoil at zero angle of attack in high Reynolds number supercritical flow. The measurements include distributions of surface static pressure and local skin friction. The instruments employed include high-frequency response pressure cells and a large array of surface hot-wire skin-friction gages. Computations at the experimental flow conditions are made using time-dependent solutions of ensemble-averaged Navier-Stokes equations, plus additional equations for the turbulence modeling.
    Keywords: AERODYNAMICS
    Type: ICAS PAPER 76-15 , Congress; Oct 03, 1976 - Oct 08, 1976; Ottawa; Canada
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Aerodynamic drag reduction tests on a full-scale tractor-trailer combination and a representative box-shaped ground vehicle (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Keywords: AERODYNAMICS
    Type: SAE PAPER 750703 , West Coast Meeting; Aug 11, 1975 - Aug 14, 1975; Seattle, WA
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    On turbulence modeling for unsteady transonic flows (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A detailed examination of the turbulent field in an unsteady transonic flow undergoing shock-induced separation is conducted. Ensemble-averaged mean and fluctuating velocities, obtained from conditionally sampled laser velocimeter data, are described and analyzed to assess the applicability of modeling concepts usually employed in steady-flow problems. Some comparisons with computations employing the Reynolds averaged Navier-Stokes equations with a mixing length turbulence model are then presented to illustrate the status of current predictive capabilities. The results appear to imply that turbulence models developed for steady flows apply and that the model need not reflect all the fine details of the turbulent structure but rather account in an approximate way for the production and destruction of the turbulence.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0071 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
    Electronic Resource
    Electronic Resource
    Tissue microenvironment and the genetic control of hair pigment patterns in mice (1979)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 1 (1979), S. 167-179 
    Details
    ISSN: 0192-253X
    Keywords: agouti locus ; hair pigment patterns ; melanocyte metabolism ; tissue microenvironment ; eumelanin ; phaeomelanin ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This study was conducted to assess microenvironmental variability within integumental tissue of genetically identical mice with respect to a specific cellular response: cyclic synthesis of yellow and black pigment by hair bulb melanocytes. Crosses were performed within and between inbred strains of mice that were isogenic with the exception of a single gene substitution at the agouti locus. Agouti locus genes included the Avy, Aw, A, atd, at, ax, am, and a alleles. The pigment patterns of dorsal, flank, and ventral hairs of the first and third hair generations and of hairs growing in special integumentary areas such as the pinna, tail, and hind foot were studied. It was found that the amount of yellow pigment synthesized by hair bulb melanocytes within genetically identical mice is both agedependent and conditioned by the integumentary environment. Furthermore, the special integumentary regions produce hairs with a variety of pigment patterns in which the distribution and relative amounts of black and yellow pigments do not necessarily conform to dominance relationships expected among agouti locus alleles as judged by their effects on the pigmentation of the dorsal pelage. We conclude that within genetically uniform integumental tissues, microenvironmental differences occur and are reflected as alterations in the metabolic pattern of differentiated cells.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020010205
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Mutations specific to spore maturation in the asexual fruiting body of dicytostelium discoideum (1979)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 1 (1979), S. 355-362 
    Details
    ISSN: 0192-253X
    Keywords: Dictyostelium discoideum ; spore maturation ; spore specific mutations ; cell patterning ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Three mutations affecting spore maturation in the asexual fruiting body of Dictyostelium discoideum are assigned to a new locus, sprJ, on linkage group IV. Strains carrying mutations at the sprJ locus do not form mature spores, yet the cell patterning (spore, stalk and disc cell ratios) is apparently normal. These mutations will be useful to delineate branch points between the cell patterning and spore maturation pathways. There are some unusual features of the sprJ-containing mutants. In particular each of the parent strains of the three mutants has incomplete spore maturation as determined by colony-forming ability after heat shocking at 45°C. A mutation allowing growth in the presence of benlate (600 μg/ml), benA351, is mapped to linkage group I.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020010408
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Salivary gland development in the blowfly, Calliphora erythrocephala (1976)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 149 (1976), S. 459-482 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The salivary gland of adult Calliphora erythrocephala is a tubular structure composed of secretory, reabsorptive, and duct regions. Development of these structures has been followed during the six days of larval and ten days of pupal growth. Two small groups of imaginal cells located at the junction between larval gland and duct give rise to the adult gland. These presumptive adult cells divide during all larval stages and appear to be functional components of the larval gland. Shortly after pupation, the larval gland breaks down and the imaginal cells proliferate rapidly, forming sequentially the duct, reabsorptive and secretory regions. Proliferating regions of the developing gland are frequently encrusted with haemocytes. As it elongates the gland establishes intimate contacts first with the basement membrane of the degenerating larval gland, later with an epithelial layer surrounding the main dorsal tracheal trunks, and then with the gut. Cell division continues until about five days after pupation, bu t the gland is unable to secrete fluid in response to 5-hydroxytryptamine stimulation until two hours after the adult fly emerges. The Golgi complex appears to be involved in forming the highly folded membranes of the canaliculi in the secretory region.Presumptive adult salivary gland cells appear to increase in number logarithmically from the time of hatching of the larva until five days after pupation. This contrasts with the development of classical imaginal discs, in which cell division ceases prior to pupation.
    Additional Material: 35 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051490403
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  • 9
    Electronic Resource
    Electronic Resource
    Mechanics of the syrinx in Gallus gallus. II. Electromyographic studies of Ad Libitum vocalizations (1977)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 152 (1977), S. 1-19 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Records of electrical activity in the tracheal muscles of domestic chickens were obtained for a variety of ad libitum vocalizations. Primary attention was given to an analysis of events during the most complex call, crowing.Three pairs of muscles, Mm. tracheohyoideus, tracheolateralis, and sternotrachealis, can affect the configuration of a chicken's syrinx. The firing patterns of the three muscle pairs are related to their different abilities to affect the tension of the syringeal membranes. The influence of M. tracheohyoideus is most indirect and imprecise, and its role the least clearly defined. It appears to adjust the position of the trachea so that the syrinx is isolated from unpredictable and/or undesirable consequences of nuchal position and tracheal elasticity, and also helps draw the glottis caudad, thereby deepening the pharyngeal chamber. The other two muscles interact to control the tension of the vocal membranes. M. sternotrachealis relaxes the membranes by drawing the drum of the trachea caudad, or, via the syringeal ligament, by rotating the pessulus cranioventrad, or both. M. tracheolateralis tenses the membranes and/or prevents caudal movement of the origin of M. sternotrachealis, a necessity if the syringeal ligament is to rotate the pessulus.Vocalization depends on both syringeal configuration and appropriate air flow. Hence, tracheal muscles, syrinx, air sacs, and ventilatory muscles cooperate to form a vocal system. Cooperation elicits a surprising degree of redundancy. At least one call, a high pitched wail, may be produced by two very different techniques.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051520102
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  • 10
    Electronic Resource
    Electronic Resource
    Centrifugal elutriation: Separation of spermatogenic cells on the basis of sedimentation velocity (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 86 (1975), S. 177-189 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Various types of cells from the testes of mice and hamsters were separated according to differences in sedimentation velocity by centrifugal elutriation, a counterflow centrifugation technique. Approximately 3 × 108 cells, prepared from six mouse testes or from one hamster testis, were separated into 11 fractions in less than two hours as compared to the 4-5 hours required for sedimentation at unit gravity (“Staput”). Fractions enriched in elongated spermatids and spermatozoa (100%), stages 1-8 spermatids (69%) and pachytene spermatocytes (58%) were obtained from mouse testis dispersions. Similarly enriched fractions were obtained from hamster cells. A single fraction enriched in stages 1-8 spermatids (mouse) was prepared in less than 30 minutes. As many as 2 × 109 cells were separated in a single procedure. Spermatogenic cells exhibited no evidence of structural damage with trypan blue and phase microscopy, and recovery was essentially 100%. Centrifugal elutriation had no effect on sperm motility or on the plating efficiency of CHO cells.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040860119
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