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  • 1
    Electronic Resource
    Electronic Resource
    Root:shoot ratios of old and modern, tall and semi-dwarf wheats in a mediterranean environment (1990)
    Springer
    Plant and soil 122 (1990), S. 89-98 
    Details
    ISSN: 1573-5036
    Keywords: harvest index ; old and modern wheats ; root:shoot ratio ; Rht genes ; root dry matter ; root length ; water use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field study tested the hypothesis that modern wheat varieties invest a lesser proportion of the total dry matter (root plus shoot) in the root system compared to old varieties. The study was carried out on a duplex soil (sand over clay) at Merredin, Western Australia in a Mediterranean type environment. We also compared the root:shoot dry matter ratios of near-isogenic lines forRht dwarfing genes. Root:shoot ratios decreased with crop growth stage and were closely related to the developmental pattern of a variety. All varieties appeared to accumulate more dry matter into shoots after the terminal spikelet stage. For the modern variety Kulin this occurred as early as 55 days after sowing (DAS), but did not occur until 90 DAS in the old variety Purple Straw. For all varieties, root dry matter reached its maximum at anthesis, while shoot dry matter continued to increase till maturity. At anthesis there were no significant differences in shoot dry matter between varieties, but from Purple Straw to Kulin root dry matter and thus root:shoot ratio decreased. The tall and dwarf isogenic lines had similar developmental and root:shoot dry matter accumulation patterns. At anthesis, the old variety Purple Straw had significantly higher root dry matter and root length density in the top 40-cm of the profile than modern variety Kulin. There were no varietal differences in rooting depth, water extraction or water use. At maturity about 30% of the total dry matter was invested in the roots among wheat varieties. Grain yield, harvest index (HI) and water use efficiency of grain (WUEgr) increased from old to modern varieties. The reduced investment of dry matter in the root system and thus the lower root:shoot ratio from early in the growing season may partly explain the increased HI and WUEgr of modern compared to old varieties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02444108
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Root:shoot ratios of old and modern, tall and semi-dwarf wheats in a mediterranean environment (1990)
    Springer
    Plant and soil 121 (1990), S. 89-98 
    Details
    ISSN: 1573-5036
    Keywords: harvest index ; old and modern wheats ; root:shoot ratio ; Rht genes ; root dry matter ; root length ; water use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field study tested the hypothesis that modern wheat varieties invest a lesser proportion of the total dry matter (root plus shoot) in the root system compared to old varieties. The study was carried out on a duplex soil (sand over clay) at Merredin, Western Australia in a Mediterranean type environment. We also compared the root:shoot dry matter ratios of near-isogenic lines for Rht dwarfing genes. Root:shoot ratios decreased with crop growth stage and were closely related to the developmental pattern of a variety. All varieties appeared to accumulate more dry matter into shoots after the terminal spikelet stage. For the modern variety Kulin this occurred as early as 55 days after sowing (DAS), but did not occur until 90 DAS in the old variety Purple Straw. For all varieties, root dry matter reached its maximum at anthesis, while shoot dry matter continued to increase till maturity. At anthesis there were no significant differences in shoot dry matter between varieties, but from Purple Straw to Kulin root dry matter and thus root:shoot ratio decreased. The tall and dwarf isogenic lines had similar developmental and root:shoot dry matter accumulation patterns. At anthesis, the old variety Purple Straw had significantly higher root dry matter and root length density in the top 40-cm of the profile than modern variety Kulin. There were no varietal differences in rooting depth, water extraction or water use. At maturity about 30% of the total dry matter was invested in the roots among wheat varieties. Grain yield, harvest index (HI) and water use efficiency of grain (WUEgr) increased from old to modern varieties. The reduced investment of dry matter in the root system and thus the lower root:shoot ratio from early in the growing season may partly explain the increased HI and WUEgr of modern compared to old varieties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00013101
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  • 3
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    Calibrating the IXPE Observatory from Ground to Space (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Imaging X-ray Polarimetry Explorer (IXPE) will be the next SMEX mission launched by NASA in 2021 in collaboration with the Italian Space Agency (ASI). IXPE will perform groundbreaking measurements of imaging polarization in X-rays for a number of different classes of sources with three identical telescopes, finally (re)opening a window in the high energy Universe after more than 40 years since the first pioneering results. The unprecedented sensitivity of IXPE to polarization poses peculiar requirements on the payload calibration, e.g. the use of polarized and completely unpolarized radiation, both on ground and in orbit, and can not rely on a systematic comparison with results obtained by previous observatories. In this paper, we will present the IXPE calibration plan, describing both calibrations which will be performed on the detectors at INAF-IAPS in Rome (Italy) and the calibration on the mirror and detector assemblies which will be carried out at Marshall Space Flight Center in Huntsville, Alabama. On orbit calibrations, performed with calibrations sources mounted on a filter wheel and placed in front of each detector when necessary, will be presented as well.
    Keywords: Optics
    Type: MSFC-E-DAA-TN47175 , SPIE Optics + Photonics 2017; Aug 06, 2017 - Aug 08, 2017; San Diego, CA; United States
    Format: application/pdf
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  • 4
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    X-Ray Optics at NASA Marshall Space Flight Center (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA's Marshall Space Flight Center (MSFC) engages in research, development, design, fabrication, coating, assembly, and testing of grazing-incidence optics (primarily) for x-ray telescope systems. Over the past two decades, MSFC has refined processes for electroformed-nickel replication of grazing-incidence optics, in order to produce high-strength, thin-walled, full-cylinder x-ray mirrors. In recent years, MSFC has used this technology to fabricate numerous x-ray mirror assemblies for several flight (balloon, rocket, and satellite) programs. Additionally, MSFC has demonstrated the suitability of this technology for ground-based laboratory applications-namely, x-ray microscopes and cold-neutron microscopes and concentrators. This mature technology enables the production, at moderately low cost, of reasonably lightweight x-ray telescopes with good (15-30 arcsecond) angular resolution. However, achieving arcsecond imaging for a lightweight x-ray telescope likely requires development of other technologies. Accordingly, MSFC is conducting a multi-faceted research program toward enabling cost-effective production of lightweight high-resolution x-ray mirror assemblies. Relevant research topics currently under investigation include differential deposition for post-fabrication figure correction, in-situ monitoring and control of coating stress, and direct fabrication of thin-walled full-cylinder grazing-incidence mirrors.
    Keywords: Optics
    Type: MSFC-E-DAA-TN22572 , EOO109 EUV and X-ray Optics: Synergy Between Laboratory and Space (SPIE 9510); Apr 13, 2015 - Apr 16, 2015; Prague, Czech Republic; Czechoslovakia
    Format: application/pdf
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  • 5
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    Predictions of the On-Orbit Performance of AXAF's Optics (1997)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: The AXAF optics and science instruments have recently undergone a battery of tests at the Marshall Space Flight Center X-Ray Calibration Facility to determine their spatial and spectral performance. We have combined these data, detailed maps of the optics, surfaces, precise measurements of surface roughness and reflectivity, and detailed mechanical models of the optics and their support structures to arrive at predictions of the optics' on-orbit performance. We present on- and off-axis effective areas, encircled energies, and PSFS.
    Keywords: Optics
    Type: Jun 08, 1997 - Jun 12, 1997; Winston-Salem, NC; United States|Bulletin of the American Astronomical Society; 29; 814
    Format: text
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  • 6
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    Absolute Calibration of the AXAF Telescope Effective Area (1997)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: The prelaunch calibration of AXAF encompasses many aspects of the telescope. In principle, all that is needed is the complete point response function. This is, however, a function of energy, off-axis angle of the source, and operating mode of the facility. No single measurement would yield the entire result. Also, any calibration made prior to launch will be affected by changes in conditions after launch, such as the change from one g to zero g. The reflectivity of the mirror and perhaps even the detectors can change as well, for example by addition or removal of small amounts of material deposited on their surfaces. In this paper, we give a broad view of the issues in performing such a calibration, and discuss how they are being addressed in prelaunch preparation of AXAF. As our title indicates, we concentrate here on the total throughput of the observatory. This can be thought of as the integral of the point response function, i.e. the encircled energy, out ot the largest practical solid angle for an observation. Since there is no standard x-ray source in the sky whose flux is known to the -1% accuracy we are trying to achieve, we must do this calibration on the ground. we also must provide a means for monitoring any possible changes in this calibration from pre-launch until on-orbit operation can transfer the calibration to a celestial x-ray source whose emission is stable. In this paper, we analyze the elements of the absolute throughput calibration, which we call Effective Area. We review the requirements for calibrations of components or subsystems of the AXAF facility, including mirror, detectors, and gratings. We show how it is necessary to calibrate this ground-based detection system at standard man-made x-ray sources, such as electron storage rings. We present the status of all these calibrations, with indications of the measurements remaining to be done, even though the measurements on the AXAF flight optics and detectors will have been completed by the time this paper is presented. We evaluate progress toward the goal of making 1% measurements of the absolute x-ray flux from astrophysical sources, so that comparisons can be made with their emission at other wavelengths, in support of observations such as the Sunyaev-Zeldovitch effect, which can give absolute distance measurements independent of the traditional distance measuring techniques in astronomy.
    Keywords: Optics
    Type: Bulletin of the American Astronomical Society; 3113; 515-525
    Format: text
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  • 7
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    Calibration Results for the AXAF Flux Contamination Monitor (1998)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: The AXAF Flux Contamination Monitor (FCM) serves the purposes of transferring the absolute flux calibration from the ground calibration at the X-Ray Calibration Facility (XRCF) to operation on orbit and of detecting any changes in molecular contamination of the High-Resolution Mirror Assembly (HRMA) between ground calibration and the post-launch activation. We describe the design, construction, and characterization of the FCM radioactive sources, and their placement on the Forward Contamination Cover (FCC). We present results from FCM measurements with the AXAF focal-plane instruments, particularly the AXAF CCD Imaging Spectrometer (ACIS), during the ground calibration phase at the XRCF in 1997. Finally, we describe the plans for FCM on-orbit measurements during observatory activation and for the subsequent analysis.
    Keywords: Optics
    Type: Jul 01, 1998; San Diego, CA; United States
    Format: text
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  • 8
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    Measurements with the Chandra X-ray Observatory's Flight Contamination Monitor (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: NASA's Chandra X-ray Observatory includes a Flight Contamination Monitor (FCM), a system of 16 radioactive calibration sources mounted to the inside of the Observatory's forward contamination cover. The purpose of the FCM is to verify the ground-to-orbit transfer of the Chandra flux scale, through comparison of data acquired during the ground calibration with those obtained in orbit, immediately prior to opening the Observatory's sun-shade door. Here we report results of these measurements., which place limits on the change in the mirror-detector system response and, hence, on any accumulation of molecular contamination on the mirrors' iridium-coated surfaces between the two sets of measurements.
    Keywords: Optics
    Type: Measurements with the Chandra X-ray Observatory''s Flight Contamination Monitor; Mar 27, 2000 - Mar 31, 2000; Munich; Germany
    Format: application/pdf
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  • 9
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    X-Ray Optics at NASA Marshall Space Flight Center (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA's Marshall Space Flight Center (MSFC) engages in research, development, design, fabrication, coating, assembly, and testing of grazing-incidence optics (primarily) for x-ray telescope systems. Over the past two decades, MSFC has refined processes for electroformed-nickel replication of grazing-incidence optics, in order to produce high-strength, thin-walled, full-cylinder x-ray mirrors. In recent years, MSFC has used this technology to fabricate numerous x-ray mirror assemblies for several flight (balloon, rocket, and satellite) programs. Additionally, MSFC has demonstrated the suitability of this technology for ground-based laboratory applications-namely, x-ray microscopes and cold-neutron microscopes and concentrators. This mature technology enables the production, at moderately low cost, of reasonably lightweight x-ray telescopes with good (15-30 arcsecond) angular resolution. However, achieving arcsecond imaging for a lightweight x-ray telescope likely requires development of other technologies. Accordingly, MSFC is conducting a multi-faceted research program toward enabling cost-effective production of lightweight high-resolution x-ray mirror assemblies. Relevant research topics currently under investigation include differential deposition for post-fabrication figure correction, in-situ monitoring and control of coating stress, and direct fabrication of thin-walled full-cylinder grazing-incidence mirrors.
    Keywords: Optics
    Type: MSFC-E-DAA-TN23440 , SPIE Optics + Optoelectronics 2015; Apr 13, 2015 - Apr 16, 2015; Prague; Czechoslovakia
    Format: application/pdf
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