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  • ENGINEERING (GENERAL)  (5)
  • Nuclear Reactions  (4)
  • Fluid Mechanics and Thermodynamics  (1)
  • Hymenoptera  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Egg Deposition Behavior in the Haplodiploid Sawfly Athalia rosae ruficornis Jakovlev (Hymenoptera: Symphyta: Tenthredinidae) (1998)
    Springer
    Journal of insect behavior 11 (1998), S. 419-428 
    Details
    ISSN: 1572-8889
    Schlagwort(e): Hymenoptera ; Athalia rosae ; egg deposition behavior ; mating ; eye color mutation ; primary sex ratio
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The egg deposition behavior of the turnip sawfly, Athalia rosae (Hymenoptera: Symphyta), is described. Both unmated and mated females lay eggs individually inside of fresh young leaves of cruciferous plants. During an oviposition event, females exhibit a distinct pause in abdominal contractions just before the actual egg deposition act. Unmated females show a longer pause (11.31 s on average) than mated females (4.38 s on overall average). By employing an eye color mutation, the sex of the eggs laid by females was ascertained. Females mated once lay mostly fertilized (diploid female) eggs initially but begin to lay a considerable number of unfertilized (haploid male) eggs later in life. The laying of an unfertilized egg is associated with a longer pause (6.98 s on average) than the laying of a fertilized egg (3.76 s on average). These results are in contrast to previous reports on apocritan Hymenoptera, where the presence of a pause or a longer pause during oviposition was associated with the deposition of fertilized eggs rather than unfertilized eggs. The possibility that mated Athalia rosae females control fertilization and its implications for sex allocation strategies are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1020958831972
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  • 2
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    Precision measurement of the ^{238}Pu(n,γ) cross section (2013)
    American Physical Society (APS)
    Details
    Publikationsdatum: 2013-10-15
    Beschreibung: Author(s): A. Chyzh, C. Y. Wu, E. Kwan, R. A. Henderson, J. M. Gostic, T. A. Bredeweg, A. Couture, R. C. Haight, H. Y. Lee, J. M. O’Donnell, and J. L. Ullmann The neutron-capture cross section for 238 Pu was measured by using the detector for advanced neutron-capture experiments (DANCE) array, which is a highly segmented and highly efficient 4 π γ -ray calorimeter. The neutron-capture events were recognized by the total γ -ray energy deposited in DANCE, which... [Phys. Rev. C 88, 044607] Published Mon Oct 14, 2013
    Schlagwort(e): Nuclear Reactions
    Print ISSN: 0556-2813
    Digitale ISSN: 1089-490X
    Thema: Physik
    Publiziert von American Physical Society (APS)
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
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    Total prompt γ-ray emission in fission of U235, Pu239,241, and Cf252 (2014)
    American Physical Society (APS)
    Details
    Publikationsdatum: 2014-07-12
    Beschreibung: Author(s): A. Chyzh, C. Y. Wu, E. Kwan, R. A. Henderson, T. A. Bredeweg, R. C. Haight, A. C. Hayes-Sterbenz, H. Y. Lee, J. M. O'Donnell, and J. L. Ullmann The total prompt γ-ray energy distributions for the neutron-induced fission of U235 and Pu239,241 in the neutron energy range of 0.025 eV – 100 keV and the spontaneous fission of Cf252 were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) in coincidence with the detection... [Phys. Rev. C 90, 014602] Published Fri Jul 11, 2014
    Schlagwort(e): Nuclear Reactions
    Print ISSN: 0556-2813
    Digitale ISSN: 1089-490X
    Thema: Physik
    Publiziert von American Physical Society (APS)
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
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    Prompt γ-ray production in neutron-induced fission of ^{239}Pu (2013)
    American Physical Society (APS)
    Details
    Publikationsdatum: 2013-04-12
    Beschreibung: Author(s): J. L. Ullmann, E. M. Bond, T. A. Bredeweg, A. Couture, R. C. Haight, M. Jandel, T. Kawano, H. Y. Lee, J. M. O’Donnell, A. C. Hayes, I. Stetcu, T. N. Taddeucci, P. Talou, D. J. Vieira, J. B. Wilhelmy, J. A. Becker, A. Chyzh, J. Gostic, R. Henderson, E. Kwan, and C. Y. Wu Background: The prompt gamma-ray spectrum from fission is important for understanding the physics of nuclear fission, and also in applications involving fission. Relatively few measurements of the prompt gamma spectrum from 239 Pu( n , f ) have been published. Purpose: This experiment measured the multipl... [Phys. Rev. C 87, 044607] Published Thu Apr 11, 2013
    Schlagwort(e): Nuclear Reactions
    Print ISSN: 0556-2813
    Digitale ISSN: 1089-490X
    Thema: Physik
    Publiziert von American Physical Society (APS)
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
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    Systematics of prompt γ-ray emission in fission (2013)
    American Physical Society (APS)
    Details
    Publikationsdatum: 2013-03-23
    Beschreibung: Author(s): A. Chyzh, C. Y. Wu, E. Kwan, R. A. Henderson, J. M. Gostic, T. A. Bredeweg, A. Couture, R. C. Haight, A. C. Hayes-Sterbenz, M. Jandel, H. Y. Lee, J. M. O’Donnell, and J. L. Ullmann The prompt γ -ray energy and multiplicity distributions were measured for the neutron-induced fission in 235 U and 239,241 Pu by using a highly segmented 4 π   γ -ray calorimeter in coincidence with the detection of fission fragments by a gas-filled parallel-plate avalanche counter. Both distributions were... [Phys. Rev. C 87, 034620] Published Fri Mar 22, 2013
    Schlagwort(e): Nuclear Reactions
    Print ISSN: 0556-2813
    Digitale ISSN: 1089-490X
    Thema: Physik
    Publiziert von American Physical Society (APS)
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
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    Design considerations for a micro-g superfluid helium fluid acquisition system (1989)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-19
    Beschreibung: The general description, the operation, and the design of a superfluid helium (SFHe) fluid acquisition system (FAS) for use under microgravity conditions is presented. For the type of FAS considered here, where fine-mesh woven screens are used to retain flowing SFHe within a gallery arm (flow) channel, those forces which determine the flow dynamics are the micro-g accelerations, liquid surface tension, and tensile strength and cumulative pressure drops along a flow path that begins at the bulk liquid and ends at the entrance to a pump. For this case, the dimensionless number, N(T) is written as the ratio between the pressure drop across the screen and the surface tension forces at the screen for low fluid velocities. Static Bond number measurements have bene taken for SFHe using 325 x 2300 twilled Dutch screen and have indicated a screen pore hydraulic radius of 0.00031 cm.
    Schlagwort(e): ENGINEERING (GENERAL)
    Materialart: Cryogenics (ISSN 0011-2275); 29; 523-527
    Format: text
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  • 7
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    Superfluid transport and its applications in space (1990)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-19
    Beschreibung: Various transport modes in superfluid helium are discussed. They include zero net mass flow and finite mass flow for pure superfluid and normal fluid flow. An attempt is made to characterize these transport modes in a common frame of reference. Two dimensionless numbers are used, namely, the dimensionless heat flux number and the dimensionless driving force number. The equations are generalized by the use of a characteristic length so that they can be applied to the transport of HE II in any geometry. The theories are then extended to applications in space. In particular, fountain effect pumps and superfluid management at zero g by vapor-liquid phase separators are discussed in detail.
    Schlagwort(e): ENGINEERING (GENERAL)
    Materialart: Cryogenics (ISSN 0011-2275); 30; 222-229
    Format: text
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  • 8
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    Modeling Orifice Pulse Tube Coolers (1996)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-18
    Beschreibung: We have developed a calculational model that treats all the components of an orifice pulse tube cooler. We base our analysis on 1-dimensional thermodynamic equations for the regenerator and we assume that all mass flows, pressure oscillations and temperature oscillations are small and sinusoidal. Non-linear pressure drop effects are included in the regenerator to account for finite pressure amplitude effects. The resulting mass flows and pressures are matched at the boundaries with the other components of the cooler: compressor, aftercooler, cold heat exchanger, pulse tube, hot heat exchanger, orifice and reservoir. The results of the calculation are oscillating pressures, mass flows and enthalpy flows in the main components of the cooler. By comparing with the calculations of other available models, we show that our model is very similar to REGEN 3 from NIST and DeltaE from Los Alamos National Lab. Our model is much easier to use than other available models because of its simple graphical interface and the fact that no guesses are required for the operating pressures or mass flows. In addition, the model only requires a few minutes of running time allowing many parameters to be optimized in a reasonable time. A version of the model is available for use over the World Wide Web at http://irtek.arc.nasa.gov. Future enhancements include adding a bypass orifice and including second order terms in steady mass streaming and steady heat transfer. A two-dimensional anelastic approximation of the fluid equations will be used as the basis for the latter analysis. Preliminary results are given in dimensionless numbers appropriate for oscillating compressible flows. The model shows how transverse heat transfer reduces enthalpy flow, particularly for small pulse tubes. The model also clearly shows mass recirculation in the open tube on the order of the tube length. They result from the higher order Reynolds stresses. An interesting result of the linearized approach is that the steady mass streaming does not affect the enthalpy flow at second order. The major effect of recirculating mass streaming is to increase transverse temperature gradients, which leads to higher entropy production and reduced efficiency.
    Schlagwort(e): Fluid Mechanics and Thermodynamics
    Materialart: WE-Heraeus Seminar on Low Power Cryocoolers; Jun 13, 1996 - Jun 15, 1996; Bad Honnef; Germany
    Format: text
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  • 9
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    Sintered plug flow modulation of a vapor-liquid phase separator for a helium II vessel (1984)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: Presented is a system for modulation of a superfluid (helium II) flow in a vapor-liquid phase separator, for use in cryogenic storage tanks in future space missions. The system consists of a semicircular mechanically operated shutter, downstream of the separator plug, rotated at 0.1 rpm to control the operational surface area of the separator. The mass flow rate was varied from 10 to 22 mg/s. Pressure gradients across the plug are also discussed.
    Schlagwort(e): ENGINEERING (GENERAL)
    Materialart: Advances in cryogenic engineering.; Aug 15, 1983 - Aug 17, 1983; Colorado Springs, CO
    Format: text
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  • 10
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    The influence of gas velocity on surface heat pumping for the orifice pulse tube refrigerator (1990)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: The basic pulse tube refrigerator produces cooling by a mechanism known as surface heat pumping. Cyclical compression and expansion of a gas within an enclosed tube produces large temperature gradients. The purpose of the tube is to act as 'nodal regenerator'. Heat is stored at node positions along the tube wall and is transported between nodes by moving gas parcels. This process gives rise to refrigeration, with hot temperatures at the closed end and cold temperatures at the open end. Unfortunately, much of the available refrigeration is not realized because the closed end of the basic pulse tube restricts gas movement - gas at the extreme temperatures does not come in contact with the heat exchangers. The orifice pulse tube overcomes this limitation by using a valve and surge volume assembly at the warm, closed end. This allows for a residual gas velocity to remain present during the heat transfer process, thereby permitting more gas to exchange heat at the heat exchangers. This paper describes the pulse tube as a nodal regenerator and the effect residual gas velocity has on the heat transfer mechanism of the orifice pulse tube.
    Schlagwort(e): ENGINEERING (GENERAL)
    Materialart: 1989 Cryogenic Engineering Conference; Jul 24, 1989 - Jul 28, 1989; Los Angeles, CA; United States
    Format: text
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