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  • PROPULSION SYSTEMS  (3)
  • dormancy  (2)
  • 25.40.-h  (1)
  • 25.60  (1)
  • Biotin  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Biotin chemoresponse in Paramecium (1998)
    Springer
    Journal of comparative physiology 183 (1998), S. 361-366 
    Details
    ISSN: 1432-1351
    Keywords: Key wordsParamecium ; Chemoattractant ; Biotin ; Chemoreceptor ; Chemokinesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Paramecium tetraurelia locate their␣foodsource by detecting bacterial metabolites and altering swimming behavior to congregate near bacterial populations on which they feed. Several attractants, such as folate, glutamate, cAMP and acetate have been identified and various aspects of chemoreception, signal transduction and effector mechanisms have been described. Here we characterize the Paramecium chemoresponse to biotin. An essential enzymatic cofactor in all cells, biotin is secreted by a large number of bacterial species during growth phase. P. tetraurelia are strongly attracted to biotin with a half-maximal behavioral response at 0.3 mmol · 1−1 in T-maze assays. Physiological recordings from whole cells show that cells hyperpolarize in a concentration-dependent manner in biotin. Whole-cell binding assays utilizing 3H-biotin identify a saturable and specific binding site with an apparent dissociation constant of 0.4 mmol · l−1. The biotin analogs desthiobiotin and biotin methyl ester are also strong attractants. Diaminobiotin fails to attract P. tetraurelia at 1 mmol · l−1, but does interfere with the biotin chemoresponse and displaces 3H-biotin from whole cells. We hypothesize that the keto group and/or fidelity of the ureido ring of biotin are necessary for biotin chemoresponse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050262
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Seed coat structure and dormancy (1992)
    Springer
    Plant growth regulation 11 (1992), S. 201-209 
    Details
    ISSN: 1573-5087
    Keywords: Seed coat structure ; dormancy ; permeability ; Dichrostachys cinerea ; natural dormancy-breaking factors ; inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An understanding of dormancy mechanisms is of ecological and economic importance. Identification of the level at which dormancy is imposed appears to be species specific. The variation brought about by this therefore requires that developmental studies be included in seed coat dormancy experiments. In most cases, a site of permeability can be identified during the developmental process, and this information can be utilized later to remove dormancy. Under natural conditions, the removal of seed coat dormancy requires the interaction of a number of ecological and physiological dormancy-breaking cues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024559
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Evidence for directp p interactions in the fragmentation channelp +α →p + pX at √s=88 GeV (1986)
    Springer
    The European physical journal 324 (1986), S. 67-73 
    Details
    ISSN: 1434-601X
    Keywords: 25.40.-h ; 25.30.+ S ; 13.85.-t
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have investigated kinematical correlations between the outgoing beam proton and the proton emerging from the fragmentingα-particle inpα collisions at $$\sqrt {s_{p\alpha } } = 88GeV$$ . Strong correlations are seen, indicating the dominance of quasi-elasticpp scattering in the fragmentation channelp+α→p+pX, for the ¦t¦ range 0.05–1.00 (GeV/c)2. A Monte Carlo simulation of this process can explain the observed correlation spectra assuming an admixture of about 16% spectator protons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01290756
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  • 4
    Electronic Resource
    Electronic Resource
    Nuclear stopping power in αα anddd collisions (1986)
    Springer
    The European physical journal 325 (1986), S. 7-14 
    Details
    ISSN: 1434-601X
    Keywords: 3.85 ; 25.50 ; 25.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Inelasticαα anddd collisions were studied at a centre-of-mass energy √S NN=31.2 GeV per nucleon-nucleon collision, using the Split-Field Magnet (SFM) detector at the CERN ISR. In this paper we show the inclusive and semi-inclusive rapidity distributions of protons, compare them with predictions of the Lund model, and calculate the average rapidity loss for participant protons. From the negative particles we calculate the inelasticity of the interaction, the average energy per particle, and the degree of isotropy of the produced hadrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294237
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  • 5
    Electronic Resource
    Electronic Resource
    The role of natural agents in the removal of coat-imposed dormancy in Dichrostachys cinerea (L.) Wight et Arn. seeds (1994)
    Springer
    Plant growth regulation 14 (1994), S. 51-59 
    Details
    ISSN: 1573-5087
    Keywords: bush encroachment ; Dichrostachys cinerea ; dormancy ; germination ; impermeability ; natural factors ; seed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstracts Dichrostachys cinerea seeds are impermeable to water and do not germinate readily. The plant, however, contributes to a bush encroachment problem, minimising visibility in wildlife reserves and reducing the area available for grazing. Natural dormancy-breaking conditions must therefore exist, promoting the germinability of these normally dormant seeds. Diurnal temperature fluctuations (50°C/15°C), especially when combined with moisture were found to break dormancy. High temperatures, such as those generated by fire, destroyed seeds. Seeds ingested by herbivorous browsers such as nyala, became permeable. Seed burial for 48 weeks, was a more effective treatment than storage in promoting permeability. Distribution of D. cinerea will therefore be restricted to areas in which these conditions or factors occur. Seeds germinated optimally at 30δC in the laboratory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024141
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  • 6
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    Experimental and theoretical determination of the admittances of a family of nozzles subjected to axial instabilities. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The interaction between the oscillations in the combustor and the wave system in the nozzle (required in combustion instability analysis of rocket engines) can be determined once the nozzle admittance is known. Experimental and theoretical methods of determining the admittance of nozzles subjected to axial oscillations are discussed. One-dimensional nozzle admittances were measured by an impedance tube technique modified to account for the presence of a mean flow. Crocco's nozzle admittance theory is applied to the prediction of admittances for several test nozzles.
    Keywords: PROPULSION SYSTEMS
    Type: Journal of Sound and Vibration; 30; Sept. 22
    Format: text
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  • 7
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    The prediction of three-dimensional liquid-propellant rocket nozzle admittances (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Crocco's three-dimensional nozzle admittance theory is extended to be applicable when the amplitudes of the combustor and nozzle oscillations increase or decrease with time. An analytical procedure and a computer program for determining nozzle admittance values from the extended theory are presented and used to compute the admittances of a family of liquid-propellant rocket nozzles. The calculated results indicate that the nozzle geometry entrance Mach number and temporal decay coefficient significantly affect the nozzle admittance values. The theoretical predictions are shown to be in good agreement with available experimental data.
    Keywords: PROPULSION SYSTEMS
    Type: NASA-CR-121129
    Format: application/pdf
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  • 8
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    Experimental determination of three dimensional liquid rocket nozzle admittances. (1972)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The three dimensional nozzle admittance, an important parameter in combustion instability studies, was experimentally measured for several nozzle configurations. The admittance values were obtained using a modification of the classical impedance tube technique. The modified impedance tube method measures the admittance of a duct termination in the presence of one dimensional mean flow and three dimensional oscillations. Values of the nozzle admittance were obtained from pressure amplitude measurements taken at discrete points along the length of the tube. To determine the effects of nozzle geometry, nozzles were tested with half-angles of 15, 30, and 45 degrees and entrance Mach numbers of 0.08, 0.16, and 0.20. The admittance results are presented as functions of nondimensional frequency for mixed first tangential-longitudinal modes. These results are compared with available theoretical predictions and favorable agreement between theory and experiment is shown.
    Keywords: PROPULSION SYSTEMS
    Type: AIAA PAPER 72-666 , American Institute of Aeronautics and Astronautics, Fluid and Plasma Dynamics Conference; Jun 26, 1972 - Jun 28, 1972; Boston, MA
    Format: text
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