1
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Werellapatha K, Hall GN, Krauland C, Krygier A, Bhandarkar N, Bradley DK, Coppari F, Gorman MG, Heinbockel C, Kemp GE, Khan SF, Lazicki A, Masters N, May MJ, Nagel SR, Palmer NE, Eggert JH, Benedetti LR. Optimized x-ray emission from 10 ns long germanium x-ray sources at the National Ignition Facility. Rev Sci Instrum 2022; 93:123902. [PMID: 36586918 DOI: 10.1063/5.0106696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 11/13/2022] [Indexed: 06/17/2023]
Abstract
This study investigates methods to optimize quasi-monochromatic, ∼10 ns long x-ray sources (XRS) for time-resolved x-ray diffraction measurements of phase transitions during dynamic laser compression measurements at the National Ignition Facility (NIF). To support this, we produce continuous and pulsed XRS by irradiating a Ge foil with NIF lasers to achieve an intensity of 2 × 1015 W/cm2, optimizing the laser-to-x-ray conversion efficiency. Our x-ray source is dominated by Ge He-α line emission. We discuss methods to optimize the source to maintain a uniform XRS for ∼10 ns, mitigating cold plasma and higher energy x-ray emission lines.
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Affiliation(s)
- K Werellapatha
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - G N Hall
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - C Krauland
- General Atomics, San Diego, California 92121, USA
| | - A Krygier
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - N Bhandarkar
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - D K Bradley
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - F Coppari
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M G Gorman
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - C Heinbockel
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - G E Kemp
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - S F Khan
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - A Lazicki
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - N Masters
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M J May
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - S R Nagel
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - N E Palmer
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - J H Eggert
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - L R Benedetti
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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2
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Opachich YP, Dodd ES, Heeter RF, Harris CD, Johns HM, Kline JL, Krasheninnikova NS, May MJ, Moore AS, Rubery MS, Schneider MB, Urbatsch TJ, Widmann K, Perry TS. DANTE as a primary temperature diagnostic for the NIF iron opacity campaign. Rev Sci Instrum 2021; 92:033519. [PMID: 33819987 DOI: 10.1063/5.0040972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
The Opacity Platform on the National Ignition Facility (NIF) has been developed to measure iron opacities at varying densities and temperatures relevant to the solar interior and to verify recent experimental results obtained at the Sandia Z-machine, that diverge from theory. The first set of NIF experiments collected iron opacity data at ∼150 eV to 160 eV and an electron density of ∼7 × 1021 cm-3, with a goal to study temperatures up to ∼210 eV, with electron densities of up to ∼3 × 1022 cm-3. Among several techniques used to infer the temperature of the heated Fe sample, the absolutely calibrated DANTE-2 filtered diode array routinely provides measurements of the hohlraum conditions near the sample. However, the DANTE-2 temperatures are consistently low compared to pre-shot LASNEX simulations for a range of laser drive energies. We have re-evaluated the estimated uncertainty in the reported DANTE-2 temperatures and also the error generated by varying channel participation in the data analysis. An uncertainty of ±5% or better can be achieved with appropriate spectral coverage, channel participation, and metrology of the viewing slot.
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Affiliation(s)
- Y P Opachich
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - E S Dodd
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - R F Heeter
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - C D Harris
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - H M Johns
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J L Kline
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | | | - M J May
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - A S Moore
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M S Rubery
- Atomic Weapons Establishment PLC, Aldermaston, Reading RG7 4PR, United Kingdom
| | - M B Schneider
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - T J Urbatsch
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - K Widmann
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - T S Perry
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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3
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Harris CD, Kemp GE, Schneider MB, Widmann K, Rubery MS, May MJ. Spectral sensor error analysis for measuring x-ray radiation drive using the DANTE diagnostic toward inertial confinement fusion experiments. Rev Sci Instrum 2021; 92:033505. [PMID: 33820103 DOI: 10.1063/5.0035584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 02/07/2021] [Indexed: 06/12/2023]
Abstract
DANTE is a diagnostic used to measure the x-radiation drive produced by heating a high-Z cavity ("hohlraum") with high-powered laser beams. It records the spectrally and temporally resolved radiation flux at x-ray energies between 50 eV and 20 keV. Each sensor configuration on DANTE is composed of filters, mirrors, and x-ray diodes to define 18 different x-ray channels whose output is voltage as a function of time. The absolute flux is then determined from the photometric calibration of the sensor configuration and a spectral reconstructing algorithm. The reconstruction of the spectra vs time from the measured voltages and known response of each channel has presented challenges. We demonstrate a novel approach here for quantifying the error on the determined flux based on the channel sensor configuration and most commonly used reconstruction algorithm. In general, we find that the integrated spectral flux from a hohlraum can robustly be reconstructed (within ∼14%) using a traditional unfold approach with as few as ten channels due to the underlying assumption of a largely Planckian spectral intensity distribution.
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Affiliation(s)
- C D Harris
- Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - G E Kemp
- Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - M B Schneider
- Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - K Widmann
- Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - M S Rubery
- Atomic Weapons Establishment, Aldermaston, Reading RG7 4PR, United Kingdom
| | - M J May
- Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
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4
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Kemp GE, May MJ, MacNeil LP, Allen FV, Brown CG, Christensen KS, Dutra EC, Esquivel CA, Martinez AN, Fisher JH, Blue BE. A compact filtered x-ray diode array spectrometer for the National Ignition Facility: SENTINEL. Rev Sci Instrum 2020; 91:123502. [PMID: 33380006 DOI: 10.1063/5.0025841] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 11/27/2020] [Indexed: 06/12/2023]
Abstract
Sentinel is a 16-channel, filtered x-ray diode array spectrometer that has been developed to measure ∼1 keV-20 keV x-ray emission generated by the National Ignition Facility (NIF) laser. Unlike the large, fixed-port versions of this diagnostic that currently exist on the NIF (known as Dante), Sentinel is a Diagnostic Instrument Manipulator compatible such that it can be fielded along the polar or equatorial lines-of-sight-an essential new capability for characterizing the often anisotropic x-ray emission from laser-driven sources. We present the diagnostic design along with preliminary diode calibrations and performance results. The novel, small-form-factor x-ray diode design allows for ≳5×-25× increased channel areal density over that of Dante, simultaneously enabling improved diagnostic robustness and fidelity of spectral reconstructions. While the Sentinel diagnostic is anticipated to improve line-of-sight spectral characterization of x-ray sources for a wide variety of programs on the NIF, the compact and portable design is also attractive to small- and mid-scale facilities with limited diagnostic real estate.
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Affiliation(s)
- G E Kemp
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M J May
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - L P MacNeil
- Nevada National Security Site, Las Vegas, Nevada 89030, USA
| | - F V Allen
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - C G Brown
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - K S Christensen
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - E C Dutra
- Nevada National Security Site, Las Vegas, Nevada 89030, USA
| | - C A Esquivel
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - A N Martinez
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - J H Fisher
- Fifth Gait Technologies, Inc., Huntsville, Alabama 35803, USA
| | - B E Blue
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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5
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Kemp GE, Rubery MS, Harris CD, May MJ, Widmann K, Heeter RF, Libby SB, Schneider MB, Blue BE. A genetic algorithm approach for reconstructing spectral content from filtered x-ray diode array spectrometers. Rev Sci Instrum 2020; 91:083507. [PMID: 32872957 DOI: 10.1063/5.0019059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 07/30/2020] [Indexed: 06/11/2023]
Abstract
Filtered diode array spectrometers are routinely employed to infer the temporal evolution of spectral power from x-ray sources, but uniquely extracting spectral content from a finite set of broad, spectrally overlapping channel spectral sensitivities is decidedly nontrivial in these under-determined systems. We present the use of genetic algorithms to reconstruct a probabilistic spectral intensity distribution and compare to the traditional approach most commonly found in the literature. Unlike many of the previously published models, spectral reconstructions from this approach are neither limited by basis functional forms nor do they require a priori spectral knowledge. While the original intent of such measurements was to diagnose the temporal evolution of spectral power from quasi-blackbody radiation sources-where the exact details of spectral content were not thought to be crucial-we demonstrate that this new technique can greatly enhance the utility of the diagnostic by providing more physical spectra and improved robustness to hardware configuration for even strongly non-Planckian distributions.
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Affiliation(s)
- G E Kemp
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M S Rubery
- Atomic Weapons Establishment, Reading RG7 4RS, United Kingdom
| | - C D Harris
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M J May
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - K Widmann
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - R F Heeter
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - S B Libby
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M B Schneider
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - B E Blue
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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6
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Vaughan JD, Ruiz CL, Fittinghoff D, May MJ, Ampleford DJ, Cooper GW, Chandler GA, Hahn K, Styron JD, McWatters BR, Torres J, Maurer AJ, Jones B. Modeling the one-dimensional imager of neutrons (ODIN) for neutron response functions at the Sandia Z facility. Rev Sci Instrum 2018; 89:10I121. [PMID: 30399775 DOI: 10.1063/1.5039366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 06/11/2018] [Indexed: 06/08/2023]
Abstract
The one-dimensional imager of neutrons (ODIN) at the Sandia Z facility consists of a 10-cm block of tungsten with rolled edges, creating a slit imager with slit widths of either 250, 500, or 750 μm. Designed with a 1-m neutron imaging line of sight, we achieve about 4:1 magnification and 500-μm axial spatial resolution. The baseline inertial confinement fusion concept at Sandia is magnetized liner inertial fusion, which nominally creates a 1-cm line source of neutrons. ODIN was designed to determine the size, shape, and location of the neutron producing region, furthering the understanding of compression quality along the cylindrical axis of magnetized liner implosions. Challenges include discriminating neutrons from hard x-rays and gammas with adequate signal-to-noise in the 2 × 1012 deuterium-deuterium (DD) neutron yield range, as well as understanding the point spread function of the imager to various imaging detectors (namely, CR-39). Modeling efforts were conducted with MCNP6.1 to determine neutron response functions for varying configurations in a clean DD neutron environment (without x-rays or gammas). Configuration alterations that will be shown include rolled-edge slit orientation and slit width, affecting the resolution and response function. Finally, the experiment to determine CR-39 neutron sensitivity, with and without a high density polyethylene (n, p) converter, an edge spread function, and resolution will be discussed.
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Affiliation(s)
- J D Vaughan
- University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - C L Ruiz
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - D Fittinghoff
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M J May
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - D J Ampleford
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - G W Cooper
- University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - G A Chandler
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - K Hahn
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - J D Styron
- University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - B R McWatters
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - J Torres
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - A J Maurer
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - B Jones
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
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7
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Opachich YP, Heeter RF, Barrios MA, Garcia EM, Craxton RS, King JA, Liedahl DA, McKenty PW, Schneider MB, May MJ, Zhang R, Ross PW, Kline JL, Moore AS, Weaver JL, Flippo KA, Perry TS. Capsule implosions for continuum x-ray backlighting of opacity samples at the National Ignition Facility. Phys Plasmas 2017; 24:063301. [PMID: 29104422 PMCID: PMC5648568 DOI: 10.1063/1.4985076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 05/09/2017] [Indexed: 06/07/2023]
Abstract
Direct drive implosions of plastic capsules have been performed at the National Ignition Facility to provide a broad-spectrum (500-2000 eV) X-ray continuum source for X-ray transmission spectroscopy. The source was developed for the high-temperature plasma opacity experimental platform. Initial experiments using 2.0 mm diameter polyalpha-methyl styrene capsules with ∼20 μm thickness have been performed. X-ray yields of up to ∼1 kJ/sr have been measured using the Dante multichannel diode array. The backlighter source size was measured to be ∼100 μm FWHM, with ∼350 ps pulse duration during the peak emission stage. Results are used to simulate transmission spectra for a hypothetical iron opacity sample at 150 eV, enabling the derivation of photometrics requirements for future opacity experiments.
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Affiliation(s)
- Y P Opachich
- National Security Technologies, LLC, Livermore, California 94550, USA
| | - R F Heeter
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M A Barrios
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - E M Garcia
- Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
| | - R S Craxton
- Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
| | - J A King
- National Security Technologies, LLC, Livermore, California 94550, USA
| | - D A Liedahl
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - P W McKenty
- Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
| | - M B Schneider
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M J May
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - R Zhang
- Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
| | - P W Ross
- National Security Technologies, LLC, Livermore, California 94550, USA
| | - J L Kline
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - A S Moore
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - J L Weaver
- Naval Research Laboratory, Washington, D.C. 20375, USA
| | - K A Flippo
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - T S Perry
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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8
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Giraldez EM, Mirkarimi PB, Emig JA, Fournier KB, Huang H, Jaquez JS, Losbanos EC, May MJ, Sain JD, Schoff ME, Teslich NE, Vu MT, Wallace RJ. Fabrication and Metrology Challenges in Making Thin, Hollow, Silver Spherical Halfraum Targets for EPEC Experiments on the National Ignition Facility. Fusion Science and Technology 2017. [DOI: 10.13182/fst13-tfm20-28] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- E. M. Giraldez
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - P. B. Mirkarimi
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550
| | - J. A. Emig
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550
| | - K. B. Fournier
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550
| | - H. Huang
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - J. S. Jaquez
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - E. C. Losbanos
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - M. J. May
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550
| | - J. D. Sain
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550
| | - M. E. Schoff
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - N. E. Teslich
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550
| | - M. T. Vu
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - R. J. Wallace
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550
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9
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May MJ, Weaver J, Widmann K, Kemp GE, Thorn D, Colvin JD, Schneider MB, Moore A, Blue BE. Understanding reconstructed Dante spectra using high resolution spectroscopy. Rev Sci Instrum 2016; 87:11E330. [PMID: 27910695 DOI: 10.1063/1.4961267] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The Dante is an 18 channel filtered diode array used at the National Ignition Facility (NIF) to measure the spectrally and temporally resolved radiation flux between 50 eV and 20 keV from various targets. The absolute flux is determined from the radiometric calibration of the x-ray diodes, filters, and mirrors and a reconstruction algorithm applied to the recorded voltages from each channel. The reconstructed spectra are very low resolution with features consistent with the instrument response and are not necessarily consistent with the spectral emission features from the plasma. Errors may exist between the reconstructed spectra and the actual emission features due to assumptions in the algorithm. Recently, a high resolution convex crystal spectrometer, VIRGIL, has been installed at NIF with the same line of sight as the Dante. Spectra from L-shell Ag and Xe have been recorded by both VIRGIL and Dante. Comparisons of these two spectroscopic measurements yield insights into the accuracy of the Dante reconstructions.
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Affiliation(s)
- M J May
- L-170 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - J Weaver
- Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC 20375, USA
| | - K Widmann
- L-170 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - G E Kemp
- L-170 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - D Thorn
- L-170 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - J D Colvin
- L-170 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - M B Schneider
- L-170 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - A Moore
- L-170 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - B E Blue
- L-170 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
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10
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Marrs RE, Widmann K, Brown GV, Heeter RF, MacLaren SA, May MJ, Moore AS, Schneider MB. Use of a priori spectral information in the measurement of x-ray flux with filtered diode arrays. Rev Sci Instrum 2015; 86:103511. [PMID: 26520959 DOI: 10.1063/1.4934542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Filtered x-ray diode (XRD) arrays are often used to measure x-ray spectra vs. time from spectrally continuous x-ray sources such as hohlraums. A priori models of the incident x-ray spectrum enable a more accurate unfolding of the x-ray flux as compared to the standard technique of modifying a thermal Planckian with spectral peaks or dips at the response energy of each filtered XRD channel. A model x-ray spectrum consisting of a thermal Planckian, a Gaussian at higher energy, and (in some cases) a high energy background provides an excellent fit to XRD-array measurements of x-ray emission from laser heated hohlraums. If high-resolution measurements of part of the x-ray emission spectrum are available, that information can be included in the a priori model. In cases where the x-ray emission spectrum is not Planckian, candidate x-ray spectra can be allowed or excluded by fitting them to measured XRD voltages. Examples are presented from the filtered XRD arrays, named Dante, at the National Ignition Facility and the Laboratory for Laser Energetics.
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Affiliation(s)
- R E Marrs
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, USA
| | - K Widmann
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, USA
| | - G V Brown
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, USA
| | - R F Heeter
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, USA
| | - S A MacLaren
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, USA
| | - M J May
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, USA
| | - A S Moore
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, USA
| | - M B Schneider
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550, USA
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11
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Park HS, Rudd RE, Cavallo RM, Barton NR, Arsenlis A, Belof JL, Blobaum KJM, El-dasher BS, Florando JN, Huntington CM, Maddox BR, May MJ, Plechaty C, Prisbrey ST, Remington BA, Wallace RJ, Wehrenberg CE, Wilson MJ, Comley AJ, Giraldez E, Nikroo A, Farrell M, Randall G, Gray GT. Grain-size-independent plastic flow at ultrahigh pressures and strain rates. Phys Rev Lett 2015; 114:065502. [PMID: 25723227 DOI: 10.1103/physrevlett.114.065502] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Indexed: 06/04/2023]
Abstract
A basic tenet of material science is that the flow stress of a metal increases as its grain size decreases, an effect described by the Hall-Petch relation. This relation is used extensively in material design to optimize the hardness, durability, survivability, and ductility of structural metals. This Letter reports experimental results in a new regime of high pressures and strain rates that challenge this basic tenet of mechanical metallurgy. We report measurements of the plastic flow of the model body-centered-cubic metal tantalum made under conditions of high pressure (>100 GPa) and strain rate (∼10(7) s(-1)) achieved by using the Omega laser. Under these unique plastic deformation ("flow") conditions, the effect of grain size is found to be negligible for grain sizes >0.25 μm sizes. A multiscale model of the plastic flow suggests that pressure and strain rate hardening dominate over the grain-size effects. Theoretical estimates, based on grain compatibility and geometrically necessary dislocations, corroborate this conclusion.
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Affiliation(s)
- H-S Park
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - R E Rudd
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - R M Cavallo
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - N R Barton
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - A Arsenlis
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - J L Belof
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - K J M Blobaum
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - B S El-dasher
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - J N Florando
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - C M Huntington
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - B R Maddox
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - M J May
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - C Plechaty
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - S T Prisbrey
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - B A Remington
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - R J Wallace
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - C E Wehrenberg
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - M J Wilson
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, USA
| | - A J Comley
- Atomic Weapons Establishment, Aldermaston, Reading RG7 4PR, United Kingdom
| | - E Giraldez
- General Atomics, 3550 General Atomics Court, San Diego, California 92121, USA
| | - A Nikroo
- General Atomics, 3550 General Atomics Court, San Diego, California 92121, USA
| | - M Farrell
- General Atomics, 3550 General Atomics Court, San Diego, California 92121, USA
| | - G Randall
- General Atomics, 3550 General Atomics Court, San Diego, California 92121, USA
| | - G T Gray
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA
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May MJ, Brown GV, Halvorson C, Schmidt A, Bower D, Tran B, Lewis P, Hagen C. Gamma ray measurements with photoconductive detectors using a dense plasma focus. Rev Sci Instrum 2014; 85:11E117. [PMID: 25430296 DOI: 10.1063/1.4891876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Photons in the MeV range emitted from the dense plasma focus (DPF) at the NSTec North Las Vegas Facility have been measured with both neutron-damaged GaAs and natural diamond photoconductive detectors (PCDs). The DPF creates or "pinches" plasmas of various gases (e.g., H2, D2, Ne, Ar., etc.) that have enough energy to create MeV photons from either bremsstrahlung and/or (n,n(')) reactions if D2 gas is used. The high bandwidth of the PCDs enabled the first ever measurement of the fast micro-pinches present in DPF plasmas. Comparisons between a slower more conventional scintillator/photomultiplier tube based nuclear physics detectors were made to validate the response of the PCDs to fast intense MeV photon signals. Significant discrepancies in the diamond PCD responses were evident.
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Affiliation(s)
- M J May
- L-281 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - G V Brown
- L-281 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - C Halvorson
- L-281 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - A Schmidt
- L-281 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - D Bower
- L-281 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - B Tran
- L-281 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - P Lewis
- L-281 Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551, USA
| | - C Hagen
- National Security Technologies, LLC, P.O. Box 98518, Las Vegas, Nevada 89193-8518, USA
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Fournier KB, Brown CG, May MJ, Compton S, Walton OR, Shingleton N, Kane JO, Holtmeier G, Loey H, Mirkarimi PB, Dunlop WH, Guyton RL, Huffman E. A geophysical shock and air blast simulator at the National Ignition Facility. Rev Sci Instrum 2014; 85:095119. [PMID: 25273784 DOI: 10.1063/1.4896119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The energy partitioning energy coupling experiments at the National Ignition Facility (NIF) have been designed to measure simultaneously the coupling of energy from a laser-driven target into both ground shock and air blast overpressure to nearby media. The source target for the experiment is positioned at a known height above the ground-surface simulant and is heated by four beams from the NIF. The resulting target energy density and specific energy are equal to those of a low-yield nuclear device. The ground-shock stress waves and atmospheric overpressure waveforms that result in our test system are hydrodynamically scaled analogs of full-scale seismic and air blast phenomena. This report summarizes the development of the platform, the simulations, and calculations that underpin the physics measurements that are being made, and finally the data that were measured. Agreement between the data and simulation of the order of a factor of two to three is seen for air blast quantities such as peak overpressure. Historical underground test data for seismic phenomena measured sensor displacements; we measure the stresses generated in our ground-surrogate medium. We find factors-of-a-few agreement between our measured peak stresses and predictions with modern geophysical computer codes.
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Affiliation(s)
- K B Fournier
- Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550, USA
| | - C G Brown
- Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550, USA
| | - M J May
- Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550, USA
| | - S Compton
- Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550, USA
| | - O R Walton
- Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550, USA
| | - N Shingleton
- Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550, USA
| | - J O Kane
- Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550, USA
| | - G Holtmeier
- Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550, USA
| | - H Loey
- Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550, USA
| | - P B Mirkarimi
- Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550, USA
| | - W H Dunlop
- Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550, USA
| | - R L Guyton
- National Securities Technologies, Vasco Rd., Livermore, California 94551, USA
| | - E Huffman
- National Securities Technologies, Vasco Rd., Livermore, California 94551, USA
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Fournier KB, May MJ, Colvin JD, Barrios MA, Patterson JR, Regan SP. Demonstration of a 13-keV Kr K-shell x-ray source at the National Ignition Facility. Phys Rev E Stat Nonlin Soft Matter Phys 2013; 88:033104. [PMID: 24125368 DOI: 10.1103/physreve.88.033104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Indexed: 06/02/2023]
Abstract
We report 3% conversion efficiency of laser energy into Kr K-shell (≈13 keV) radiation, consistent with theoretical predictions. This is ≈10× greater than previous work. The emission was produced from a 4.1-mm-diameter, 4-mm-tall gas pipe target filled with 1.2 or 1.5 atm of Kr gas. 160 of the National Ignition Facility laser beams deposited ≈700 kJ of 3ω light into the target in an ≈140 TW, 5.0-ns-duration square pulse. The Dante diagnostics measured ≈5 TW into 4π solid angle of ≥12 keV x rays for ≈4 ns, which includes both continuum emission and flux in the Kr He_{α} line at 13 keV.
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Affiliation(s)
- K B Fournier
- Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94550, USA
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15
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Cone KV, Baldis HA, Dunn J, May MJ, Purvis MA, Schneider MB, Scott HA. Time-resolved soft x-ray spectra from laser-produced Cu plasma. Rev Sci Instrum 2012; 83:10E138. [PMID: 23126959 DOI: 10.1063/1.4739071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated by a plasma produced using the Lawrence Livermore National Laboratory's Compact Multipulse Terawatt (COMET) laser. A variable spaced grating spectrometer coupled to an x-ray streak camera measured soft x-ray emission (800-1550 eV) from the back of the copper target to characterize the bulk heating of the target. Radiation hydrodynamic simulations were modeled in two-dimensions using the HYDRA code. The target conditions calculated by HYDRA were post-processed with the atomic kinetics code CRETIN to generate synthetic emission spectra. A comparison between the experimental and simulated spectra indicates the presence of specific ionization states of copper and the corresponding electron temperatures and ion densities throughout the laser-heated copper target.
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Affiliation(s)
- K V Cone
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
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May MJ, Patterson JR, Sorce C, Widmann K, Fournier KB, Perez F. Source geometric considerations for OMEGA Dante measurements. Rev Sci Instrum 2012; 83:10E117. [PMID: 23126939 DOI: 10.1063/1.4734041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The Dante is a 15 channel filtered diode array which is installed on the OMEGA laser facility at the Laboratory for Laser Energetics, University of Rochester. The system yields the spectrally and temporally resolved radiation flux from 50 eV to 10 keV from various targets (i.e., Hohlraum, gas pipes, etc.). The absolute flux is determined from the radiometric calibration of the x-ray diodes, filters, and mirrors and an unfold algorithm applied to the recorded voltages from each channel. The unfold algorithm assumes an emitting source that is spatially uniform and has a constant area as a function of photon energy. The emitting x-ray source is usually considered to be the laser entrance hole (LEH) of a given diameter for Hohlraum type targets or the effective wall area of high conversion efficiency K-shell type targets. This assumption can be problematic for several reasons. High intensity regions or "hot spots" in the x-ray are observed where the drive laser beams strike the target. The "hot spots" create non-uniform emission seen by the Dante. Additionally, thinned walled (50 μm) low-Z targets (C(22)H(10)N(2)O(5)) have an energy dependent source size since the target's walls will be fully opaque for low energies (E < 2-3 keV) yet fully transmissive at higher energies. Determining accurate yields can be challenging for these types of targets. Discussion and some analysis will be presented.
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Affiliation(s)
- M J May
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
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May MJ, Hansen SB, Scofield J, Schneider M, Wong K, Beiersdorfer P. Gold charge state distributions in highly ionized, low-density beam plasmas. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 84:046402. [PMID: 22181278 DOI: 10.1103/physreve.84.046402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 06/27/2011] [Indexed: 05/31/2023]
Abstract
We present a systematic study of Au charge state distributions (CSDs) from low density, nonlocal thermodynamic equilibrium plasmas created in the Livermore electron beam ion traps (EBIT-I and EBIT-II). X-ray emission from Ni-like to Kr-like Au ions has been recorded from monoenergetic electron beam plasmas having E(beam)=2.66, 2.92, 3.53, and 4.54 keV, and the CSDs of the beam plasmas have been inferred by fitting the collisionally excited line transitions and radiative recombination emission features with synthetic spectra. We have modeled the beam plasmas using a collisional-radiative code with various treatments of the atomic structure for the complex M- and N-shell ions and find that only models with extensive doubly excited states can properly account for the dielectronic recombination (DR) channels that control the CSDs. This finding would be unremarkable for plasmas with thermal electron distributions, where many such states are sampled, and the importance of DR is well established. But in an EBIT source, the beam is resonant with only a subset of such states having spectator electrons in orbitals with high principal quantum number n (8≤n≤20). The inclusion of such states in the model was also necessary to obtain agreement with observed stabilizing transitions in the x-ray spectra.
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Affiliation(s)
- M J May
- PO Box 808 L260, Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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Cone KV, Dunn J, Schneider MB, Baldis HA, Brown GV, Emig J, James DL, May MJ, Park J, Shepherd R, Widmann K. Development of a time-resolved soft x-ray spectrometer for laser produced plasma experiments. Rev Sci Instrum 2010; 81:10E318. [PMID: 21034016 DOI: 10.1063/1.3492407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A 2400 lines/mm variable-spaced grating spectrometer has been used to measure soft x-ray emission (8-22 Å) from laser-produced plasma experiments at Lawrence Livermore National Laboratory's Compact Multipulse Terrawatt (COMET) Laser Facility. The spectrometer was coupled to a Kentech x-ray streak camera to study the temporal evolution of soft x rays emitted from the back of the Mylar and the copper foils irradiated at 10(15) W/cm(2). The instrument demonstrated a resolving power of ∼120 at 19 Å with a time resolution of 31 ps. The time-resolved copper emission spectrum was consistent with a photodiode monitoring the laser temporal pulse shape and indicated that the soft x-ray emission follows the laser heating of the target. The time and spectral resolutions of this diagnostic make it useful for studies of high temperature plasmas.
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Affiliation(s)
- K V Cone
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
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Park J, Brown GV, Schneider MB, Baldis HA, Beiersdorfer P, Cone KV, Kelley RL, Kilbourne CA, Magee EW, May MJ, Porter FS. Calibration of a flat field soft x-ray grating spectrometer for laser produced plasmas. Rev Sci Instrum 2010; 81:10E319. [PMID: 21034017 DOI: 10.1063/1.3495790] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We have calibrated the x-ray response of a variable line spaced grating spectrometer, known as the VSG, at the Fusion and Astrophysics Data and Diagnostic Calibration Facility at the Lawrence Livermore National Laboratory (LLNL). The VSG has been developed to diagnose laser produced plasmas, such as those created at the Jupiter Laser Facility and the National Ignition Facility at LLNL and at both the Omega and Omega EP lasers at the University of Rochester's Laboratory for Laser Energetics. The bandwidth of the VSG spans the range of ∼6-60 Å. The calibration results presented here include the VSG's dispersion and quantum efficiency. The dispersion is determined by measuring the x rays emitted from the hydrogenlike and heliumlike ions of carbon, nitrogen, oxygen, neon, and aluminum. The quantum efficiency is calibrated to an accuracy of 30% or better by normalizing the x-ray intensities recorded by the VSG to those simultaneously recorded by an x-ray microcalorimeter spectrometer.
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Affiliation(s)
- J Park
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808, USA.
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20
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Abstract
The Dante is an 18 channel x-ray filtered diode array which records the spectrally and temporally resolved radiation flux from various targets (e.g., hohlraums, etc.) at x-ray energies between 50 eV and 10 keV. It is a main diagnostic installed on the OMEGA laser facility at the Laboratory for Laser Energetics, University of Rochester. The absolute flux is determined from the photometric calibration of the x-ray diodes, filters and mirrors, and an unfold algorithm. Understanding the errors on this absolute measurement is critical for understanding hohlraum energetic physics. We present a new method for quantifying the uncertainties on the determined flux using a Monte Carlo parameter variation technique. This technique combines the uncertainties in both the unfold algorithm and the error from the absolute calibration of each channel into a one sigma Gaussian error function. One thousand test voltage sets are created using these error functions and processed by the unfold algorithm to produce individual spectra and fluxes. Statistical methods are applied to the resultant set of fluxes to estimate error bars on the measurements.
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Affiliation(s)
- M J May
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
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21
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Fournier KB, Celeste J, Rekow V, Bopp DR, May MJ, Fisher JH, Horton R, Newlander CD, Jenkins P, Trautz K. A test cassette for x-ray-exposure experiments at the National Ignition Facility. Rev Sci Instrum 2010; 81:075113. [PMID: 20687765 DOI: 10.1063/1.3470684] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We present the design and operation of a test cassette for exposure of samples to radiation environments at the National Ignition Facility. The cassette provides options for square and round samples and exposure areas; the cassette provides for multiple levels of filtration on a single sample, which allows dynamic range in experiments. The samples had normal lines of sight to the x-ray source in order to have uniform x-ray illumination. The incident x-radiation onto the samples was determined by the choice of filter thicknesses and materials. The samples were held at precise locations, accurate to within a few hundred microns, in the target chamber in order to have a known fluence incident. In the cassette, the samples were held in place in such a way that a minimal "line contact" allows them to have the maximal mechanical response to the x-ray load. We present postshot images of the debris found on films used for filters, and pre- and postexposure specimens.
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Affiliation(s)
- K B Fournier
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
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Abstract
The nuclear factor kappa B (NF-kappaB) transcription factors are activated by a range of stimuli including pro-inflammatory cytokines. Active NF-kappaB regulates the expression of genes involved in inflammation and cell survival and aberrant NF-kappaB activity plays pathological roles in certain types of cancer and diseases characterized by chronic inflammation. NF-kappaB signaling is an attractive target for the development of novel anti-inflammatory or anti-cancer drugs and we discuss here how the method of peptide transduction has been used to specifically target NF-kappaB. Peptide transduction relies on the ability of certain small cell-penetrating peptides (CPPs) to enter cells, and a panel of CPP-linked inhibitors (CPP-Is) has been developed to directly inhibit NF-kappaB signaling. Remarkably, several of these NF-kappaB-targeting CPP-Is are effective in vivo and therefore offer exciting potential in the clinical setting.
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Affiliation(s)
- J S Orange
- Department of Pediatrics, University of Pennsylvania School of Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
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May MJ, Halvorson C, Perry T, Weber F, Young P, Silbernagel C. Photoconductive detectors with fast temporal response for laser produced plasma experiments. Rev Sci Instrum 2008; 79:10E304. [PMID: 19044466 DOI: 10.1063/1.2955614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Processes during laser plasma experiments typically have time scales that are less than 100 ps. The measurement of these processes requires x-ray detectors with fast temporal resolution. We have measured the temporal responses and linearity of several different x-ray sensitive photoconductive detectors (PCDs). The active elements of the detectors investigated include both diamond (natural and synthetic) and GaAs crystals. The typical time responses of the GaAs PCDs are approximately 60 ps, respectively. Some characterizations using x-ray radiation from a synchrotron radiation source are presented.
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Affiliation(s)
- M J May
- Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550, USA
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Leeper RJ, Ruiz CL, Chandler GA, Cooper GW, Bower DE, Fittinghoff DN, Hagen EC, Hollaway JR, McKenna IJ, McPherson LA, May MJ, Meeham BT, Nelson AJ, Perry TS, Porter JL, Robbins LL, Sinars DB, Torres JA, Ziegler LH. ZR neutron diagnostic suite. ACTA ACUST UNITED AC 2008. [DOI: 10.1088/1742-6596/112/3/032076] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Currently, the UK has no procedure for the approval of novel agricultural practices that is based on environmental risk management principles. Here, we make a first application of the 'bow-tie' risk management approach in agriculture, for assessment of land use changes, in a case study of the introduction of genetically modified herbicide tolerant (GMHT) sugar beet. There are agronomic and economic benefits, but indirect environmental harm from increased weed control is a hazard. The Farm Scale Evaluation (FSE) trials demonstrated reduced broad-leaved weed biomass and seed production at the field scale. The simplest mitigation measure is to leave a proportion of rows unsprayed in each GMHT crop field. Our calculations, based on FSE data, show that a maximum of 2% of field area left unsprayed is required to mitigate weed seed production and 4% to mitigate weed biomass production. Tilled margin effects could simply be mitigated by increasing the margin width from 0.5 to 1.5 m. Such changes are cheap and simple to implement in farming practices. This case study demonstrates the usefulness of the bow-tie risk management approach and the transparency with which hazards can be addressed. If adopted generally, it would help to enable agriculture to adopt new practices with due environmental precaution.
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Affiliation(s)
- J D Pidgeon
- Broom's Barn Research Station, Higham, Bury St Edmunds, Suffolk IP28 6NP, UK.
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Heeter RF, Hansen SB, Fournier KB, Foord ME, Froula DH, Mackinnon AJ, May MJ, Schneider MB, Young BKF. Benchmark measurements of the ionization balance of non-local-thermodynamic-equilibrium gold plasmas. Phys Rev Lett 2007; 99:195001. [PMID: 18233081 DOI: 10.1103/physrevlett.99.195001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Indexed: 05/25/2023]
Abstract
We present a series of benchmark measurements of the ionization balance of well-characterized gold plasmas with and without external radiation fields at electron densities near 10{21} cm{-3} and electron temperatures spanning the range 0.8 to 2.4 keV. We have analyzed time- and space-resolved M-shell gold emission spectra using a sophisticated collisional-radiative model with hybrid level structure, finding average ion charges Z ranging from 42 to 50. At the lower temperatures, the spectra exhibit significant sensitivity to external radiation fields and include emission features from complex N-shell ions. The measured spectra and inferred Z provide a stringent test for non-local-thermodynamic-equilibrium models of complex high-Z ions.
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Affiliation(s)
- R F Heeter
- Lawrence Livermore National Laboratory, L-473, Livermore, CA 94550, USA
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27
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Firbank LG, Rothery P, May MJ, Clark SJ, Scott RJ, Stuart RC, Boffey CWH, Brooks DR, Champion GT, Haughton AJ, Hawes C, Heard MS, Dewar AM, Perry JN, Squire GR. Effects of genetically modified herbicide-tolerant cropping systems on weed seedbanks in two years of following crops. Biol Lett 2007; 2:140-3. [PMID: 17148348 PMCID: PMC1617187 DOI: 10.1098/rsbl.2005.0390] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Farm Scale Evaluations (FSEs) showed that genetically modified herbicide-tolerant (GMHT) cropping systems could influence farmland biodiversity because of their effects on weed biomass and seed production. Recently published results for winter oilseed rape showed that a switch to GMHT crops significantly affected weed seedbanks for at least 2 years after the crops were sown, potentially causing longer-term effects on other taxa. Here, we seek evidence for similar medium-term effects on weed seedbanks following spring-sown GMHT crops, using newly available data from the FSEs. Weed seedbanks following GMHT maize were significantly higher than following conventional varieties for both the first and second years, while by contrast, seedbanks following GMHT spring oilseed rape were significantly lower over this period. Seedbanks following GMHT beet were smaller than following conventional crops in the first year after the crops had been sown, but this difference was much reduced by the second year for reasons that are not clear. These new data provide important empirical evidence for longer-term effects of GMHT cropping on farmland biodiversity.
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Affiliation(s)
- L G Firbank
- Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP, UK.
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Perry JN, Firbank LG, Champion GT, Clark SJ, Heard MS, May MJ, Hawes C, Squire GR, Rothery P, Woiwod IP, Pidgeon JD. Ban on triazine herbicides likely to reduce but not negate relative benefits of GMHT maize cropping. Nature 2004; 428:313-6. [PMID: 15001990 DOI: 10.1038/nature02374] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2004] [Accepted: 01/27/2004] [Indexed: 11/09/2022]
Abstract
The UK Farm-Scale Evaluations (FSE) compared the effects on biodiversity of management of genetically modified herbicide-tolerant (GMHT) spring-sown crops with conventional crop management. The FSE reported larger weed abundance under GMHT management for fodder maize, one of three crops studied. Increased seed production may be important for the long-term persistence of these arable weeds and may benefit invertebrates, small mammals and seed-eating birds. In three-quarters of FSE maize fields, growers used atrazine on the conventionally managed half, reflecting contemporary commercial practice. Withdrawal of the triazine herbicides atrazine, simazine and cyanazine from approved lists of EU chemicals could therefore reduce or even reverse the reported benefits of GMHT maize. Here we analyse effects of applications of triazine herbicides in conventional maize regimes on key indicators, using FSE data. Weed abundances were decreased greatly relative to all other regimes whenever atrazine was applied before weeds emerged. Here, we forecast weed abundances in post-triazine herbicide regimes. We predict weed abundances under future conventional herbicide management to be considerably larger than that for atrazine used before weeds emerged, but still smaller than for the four FSE sites analysed that used only non-triazine herbicides. Our overall conclusion is that the comparative benefits for arable biodiversity of GMHT maize cropping would be reduced, but not eliminated, by the withdrawal of triazines from conventional maize cropping.
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Affiliation(s)
- J N Perry
- Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
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Squire GR, Brooks DR, Bohan DA, Champion GT, Daniels RE, Haughton AJ, Hawes C, Heard MS, Hill MO, May MJ, Osborne JL, Perry JN, Roy DB, Woiwod IP, Firbank LG. On the rationale and interpretation of the Farm Scale Evaluations of genetically modified herbicide-tolerant crops. Philos Trans R Soc Lond B Biol Sci 2003; 358:1779-99. [PMID: 14561314 PMCID: PMC1693276 DOI: 10.1098/rstb.2003.1403] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Farmland biodiversity and food webs were compared in conventional and genetically modified herbicide-tolerant (GMHT) crops of beet (Beta vulgaris L.), maize (Zea mays L.) and both spring and winter oilseed rape (Brassica napus L.). GMHT and conventional varieties were sown in a split-field experimental design, at 60-70 sites for each crop, spread over three starting years beginning in 2000. This paper provides a background to the study and the rationale for its design and interpretation. It shows how data on environment, field management and the biota are used to assess the current state of the ecosystem, to define the typical arable field and to devise criteria for selecting, sampling and auditing experimental sites in the Farm Scale Evaluations. The main functional and taxonomic groups in the habitat are ranked according to their likely sensitivity to GMHT cropping, and the most responsive target organisms are defined. The value of the seedbank as a baseline and as an indicator of historical trends is proposed. Evidence from experiments during the twentieth century is analysed to show that large changes in field management have affected sensitive groups in the biota by ca. 50% during a year or short run of years--a figure against which to assess any positive or negative effects of GMHT cropping. The analysis leads to a summary of factors that were, and were not, examined in the first 3 years of the study and points to where modelling can be used to extrapolate the effects to the landscape and the agricultural region.
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Affiliation(s)
- G R Squire
- Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, UK.
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Champion GT, May MJ, Bennett S, Brooks DR, Clark SJ, Daniels RE, Firbank LG, Haughton AJ, Hawes C, Heard MS, Perry JN, Randle Z, Rossall MJ, Rothery P, Skellern MP, Scott RJ, Squire GR, Thomas MR. Crop management and agronomic context of the Farm Scale Evaluations of genetically modified herbicide-tolerant crops. Philos Trans R Soc Lond B Biol Sci 2003; 358:1801-18. [PMID: 14561315 PMCID: PMC1693273 DOI: 10.1098/rstb.2003.1405] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Farm Scale Evaluations of genetically modified herbicide-tolerant crops (GMHT) were conducted in the UK from 2000 to 2002 on beet (sugar and fodder), spring oilseed rape and forage maize. The management of the crops studied is described and compared with current conventional commercial practice. The distribution of field sites adequately represented the areas currently growing these crops, and the sample contained sites operated at a range of management intensities, including low intensity. Herbicide inputs were audited, and the active ingredients used and the rates and the timings of applications compared well with current practice for both GMHT and conventional crops. Inputs on sugar beet were lower than, and inputs on spring oilseed rape and forage maize were consistent with, national averages. Regression analysis of herbicide-application strategies and weed emergence showed that inputs applied by farmers increased with weed densities in beet and forage maize. GMHT crops generally received only one herbicide active ingredient per crop, later and fewer herbicide sprays and less active ingredient (for beet and maize) than the conventional treatments. The audit of inputs found no evidence of bias.
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Affiliation(s)
- G T Champion
- Broom's Barn Research Station, Higham, Bury St Edmunds, Suffolk IP28 6NP, UK.
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May MJ, Fournier KB, Beiersdorfer P, Chen H, Wong KL. X-ray spectral measurements and collisional radiative modeling of Ni- to Kr-like Au ions in electron beam ion trap plasmas. Phys Rev E Stat Nonlin Soft Matter Phys 2003; 68:036402. [PMID: 14524898 DOI: 10.1103/physreve.68.036402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2003] [Indexed: 05/24/2023]
Abstract
The line emission of n=7-->3, 6-->3, 5-->3, and 4-->3 transitions in Ni- to Kr-like gold ions produced in the Livermore electron beam ion traps EBIT-I and EBIT-II has been recorded with an x-ray crystal spectrometer and a photometrically calibrated microcalorimeter. The plasmas had either monoenergetic electron beams with E(beam)=2.66, 3.53, or 4.54 keV or an experimentally simulated thermal electron distributions with T(e)=2.5 keV. The electron densities were approximately 10(12)cm(-3). The measured spectra have been compared to atomic structure calculations and synthetic spectra provided by the Hebrew University Lawrence Livermore Atomic Code atomic data package. Line identifications and accurate photon energy measurements have been made for many collisionally excited transitions. Approximately 140 lines have been identified in nine charge states. Agreement within 20-30 % exists between the measured and modeled line intensities for most lines excited by the monoenergetic electron beam plasmas, although some larger discrepancies can be found for some weaker features.
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Affiliation(s)
- M J May
- Lawrence Livermore National Laboratory, P.O. Box 808 L260, Livermore, California 94551, USA
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Wong KL, May MJ, Beiersdorfer P, Fournier KB, Wilson B, Brown GV, Springer P, Neill PA, Harris CL. Determination of the charge state distribution of a highly ionized coronal Au plasma. Phys Rev Lett 2003; 90:235001. [PMID: 12857265 DOI: 10.1103/physrevlett.90.235001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2002] [Indexed: 05/24/2023]
Abstract
We present the first definitive measurement of the charge state distribution of a highly ionized gold plasma in coronal equilibrium. The experiment utilized the Livermore electron beam ion trap EBIT-II in a novel configuration to create a plasma with a Maxwellian temperature of 2.5 keV. The charge balance in the plasma was inferred from spectral line emission measurements which accounted for charge exchange effects. The measured average ionization state was 46.8+/-0.75. This differs from the predictions of two modeling codes by up to four charge states.
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Affiliation(s)
- K L Wong
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551, USA
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Firbank LG, Heard MS, Woiwod IP, Hawes C, Haughton AJ, Champion GT, Scott RJ, Hill MO, Dewar AM, Squire GR, May MJ, Brooks DR, Bohan DA, Daniels RE, Osborne JL, Roy DB, Black HIJ, Rothery P, Perry JN. An introduction to the Farm-Scale Evaluations of genetically modified herbicide-tolerant crops. J Appl Ecol 2003. [DOI: 10.1046/j.1365-2664.2003.00787.x] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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May MJ, Finkenthal M, Moos HW, Fournier KB, Goldstein WH, Mattioli M, Pacella D, Mazzitelli G, Leigheb M, Gabellieri L. Observations of the vacuum ultraviolet and x-ray brightness profiles of Fe, Ni, and Ge in magnetically confined fusion plasmas. Phys Rev E Stat Nonlin Soft Matter Phys 2001; 64:036406. [PMID: 11580453 DOI: 10.1103/physreve.64.036406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2001] [Indexed: 05/23/2023]
Abstract
The spatial brightness profiles of emission lines for the K-like through He-like ionization states of Fe, Ge, and Ni have been measured during a set of experiments in which Fe and Ge were introduced into FTU tokamak plasmas by using the laser blowoff technique. Nickel was an intrinsic impurity observed during these experiments that was sputtered from the inconel limiter. The brightness profiles were measured by spatially scanable, photometrically calibrated vaccum ultraviolet and x-ray spectrometers that covered the 1 to 1700 A region. Simulations of these profiles and the time evolution of the laser blowoffs were performed with the MIST transport code using several sets of atomic physics compilations [ADPAK (originally in MIST), Arnaud and Raymond (AR92), Arnaud and Rothenflug (AR85), Mazzotta et al., and Mattioli (an extension to Mazzotta)]. The goal was to determine which set of available rates could best simulate the measured spatial brightness profiles and the charge state balance in the plasma. The Mazzotta et al. (for Fe and Ni), the Mattioli (for Ge), and the AR92 (for Fe only) rates adequately simulated the He-, Li-, Be-, Na-, Mg-like ionization states. The F- to B-like charge states could not be simulated by these compilations unless the relevant dielectronic rates were multiplied by a factor of 2. The ADPAK rates could not adequately predict any of the charge states of Fe, Ge, or Ni.
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Affiliation(s)
- M J May
- Plasma Spectroscopy Group, Department of Physics and Astronomy, The Johns Hopkins University, 34th and North Charles Streets, Baltimore, Maryland 21218, USA
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Abstract
A new, non-destructive assay is described to quantify cytoplasmic glutathione (GSH) levels in vivo in single cells or populations of cells from Arabidopsis suspension cultures. Cytoplasmic GSH was labelled with monochlorobimane (MCB) in situ to give a fluorescent GSH-bimane (GSB) conjugate. At low (10-100 microM) concentrations of MCB, labelling was mediated by a glutathione S-transferase, which confers specificity for GSH. HPLC analysis of MCB-labelled low molecular-weight thiols showed that the assay measures the total GSH pool, including the oxidized glutathione. The progress curve for the labelling could be described using Michaelis-Menten kinetics with an apparent KM of 40 microM and Vmax of 470 micromol lcyt -1 min-1. There was no evidence for de novo synthesis of GSH during the labelling period of 2 h, suggesting that control of GSH synthesis is not mediated by feedback control of gamma-glutamylcysteine synthetase in this system. The total cellular level of GSH was calculated from the plateau value of the progress curve, after appropriate calibration, as 830-942 nmol g-1 FW. The volume fraction of cytoplasm was measured from serial optical sections of bimane-labelled cells collected by confocal laser scanning microscopy (CLSM) with excitation 442 nm, or two-photon laser scanning microscopy (TPLSM) with excitation 770 nm. A value of 42 +/- 3% cytoplasm was determined by manual segmentation, and a value of 37 +/- 2% using stereological techniques. Using these figures, values for cytoplasmic [GSH] were estimated to be between 2.7 +/- 0.3 and 3.2 +/- 0.3 mM for cell populations. In addition, measurement of GSH levels in individual cells using CLSM and TPLSM gave values of 3.0 +/- 0.5 and 3.5 +/- 0.7 mM, respectively.
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Affiliation(s)
- A J Meyer
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
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May MJ, D'Acquisto F, Madge LA, Glöckner J, Pober JS, Ghosh S. Selective inhibition of NF-kappaB activation by a peptide that blocks the interaction of NEMO with the IkappaB kinase complex. Science 2000; 289:1550-4. [PMID: 10968790 DOI: 10.1126/science.289.5484.1550] [Citation(s) in RCA: 555] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Activation of the transcription factor nuclear factor (NF)-kappaB by proinflammatory stimuli leads to increased expression of genes involved in inflammation. Activation of NF-kappaB requires the activity of an inhibitor of kappaB (IkappaB)-kinase (IKK) complex containing two kinases (IKKalpha and IKKbeta) and the regulatory protein NEMO (NF-kappaB essential modifier). An amino-terminal alpha-helical region of NEMO associated with a carboxyl-terminal segment of IKKalpha and IKKbeta that we term the NEMO-binding domain (NBD). A cell-permeable NBD peptide blocked association of NEMO with the IKK complex and inhibited cytokine-induced NF-kappaB activation and NF-kappaB-dependent gene expression. The peptide also ameliorated inflammatory responses in two experimental mouse models of acute inflammation. The NBD provides a target for the development of drugs that would block proinflammatory activation of the IKK complex without inhibiting basal NF-kappaB activity.
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Affiliation(s)
- M J May
- Section of Immunobiology and Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06510, USA
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Abstract
PURPOSE To describe an uncommon ocular presentation of acute megakaryoblastic leukemia in a child with Down syndrome. METHOD Case report. Initial manifestation of disease was bilateral proptosis with secondary exposure keratitis caused by leukemic infiltration of the orbits. RESULTS Bone marrow biopsy and immunophenotyping established the diagnosis of acute megakaryoblastic leukemia (FAB-M7). The leukemia was treated successfully with chemotherapy, with resolution of proptosis. The patient remained in remission more than 1 year after cessation of treatment. CONCLUSIONS Bilateral proptosis can be a presenting sign of acute megakaryoblastic leukemia, a malignancy associated with Down syndrome.
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Affiliation(s)
- J L Olson
- Ophthalmology Rocky Mountain Lions Eye Institute, Denver, Colorado, 80262, USA
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Pacella D, Fournier KB, Zerbini M, Finkenthal M, Mattioli M, May MJ, Goldstein WH. Temperature and impurity transport studies of heated tokamak plasmas by means of a collisional-radiative model of x-ray emission from Mo30+ to Mo39+. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 61:5701-5709. [PMID: 11031629 DOI: 10.1103/physreve.61.5701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/1999] [Indexed: 05/23/2023]
Abstract
This work presents and interprets, by means of detailed atomic calculations, observations of L-shell (n = 3-->n = 2) transitions in highly ionized molybdenum, the main intrinsic heavy impurity in the Frascati tokamak upgrade plasmas. These hot plasmas were obtained by additional electron cyclotron resonance heating (ECRH), at the frequency of 140 Ghz, during the current ramp-up phase of the discharge. Injecting 400 kW on axis and 800 kW slightly off axis, the peak central electron temperature reached 8.0 and 7.0 keV, respectively, for a time much longer than the ionization equilibrium time of the molybdenum ions. X-ray emissions from rarely observed high charge states, Mo30+ to Mo39+, have been studied with moderate spectral resolution (lambda/delta lambda approximately 150) and a time resolution of 5 ms. A sophisticated collisional-radiative model for the study of molybdenum ions in plasmas with electron temperature in the range 4-20 keV is presented. The sensitivity of the x-ray emission to the temperature and to impurity transport processes is discussed. This model has been then used to investigate two different plasma scenarios. In the first regime the ECRH heating occurs on axis during the current ramp up phase, when the magnetic shear is evolving from negative to zero up to the half radius. The spectrum is well reproduced with the molybdenum ions in coronal equilibrium and with a central impurity peaking. In the second regime, at the beginning of the current flat top when magnetic shear is monotonic and sawtoothing activity is appearing, the lowest charge states (Mo33+ to Mo30+), populated off axis, are affected by anomalous transport and the total molybdenum profile is found to be flat up to the half radius. We conclude with the presentation of "synthetic spectra" computed for even higher temperature plasmas that are expected in future experiments with higher ECRH power input.
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Affiliation(s)
- D Pacella
- Associazione EURATOM-ENEA sulla Fusione, Rome, Italy
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Vernoux T, Wilson RC, Seeley KA, Reichheld JP, Muroy S, Brown S, Maughan SC, Cobbett CS, Van Montagu M, Inzé D, May MJ, Sung ZR. The ROOT MERISTEMLESS1/CADMIUM SENSITIVE2 gene defines a glutathione-dependent pathway involved in initiation and maintenance of cell division during postembryonic root development. Plant Cell 2000. [PMID: 10634910 DOI: 10.2307/3871032] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Activation of cell division in the root apical meristem after germination is essential for postembryonic root development. Arabidopsis plants homozygous for a mutation in the ROOT MERISTEMLESS1 (RML1) gene are unable to establish an active postembryonic meristem in the root apex. This mutation abolishes cell division in the root but not in the shoot. We report the molecular cloning of the RML1 gene, which encodes the first enzyme of glutathione (GSH) biosynthesis, gamma-glutamylcysteine synthetase, and which is allelic to CADMIUM SENSITIVE2. The phenotype of the rml1 mutant, which was also evident in the roots of wild-type Arabidopsis and tobacco treated with an inhibitor of GSH biosynthesis, could be relieved by applying GSH to rml1 seedlings. By using a synchronized tobacco cell suspension culture, we showed that the G(1)-to-S phase transition requires an adequate level of GSH. These observations suggest the existence of a GSH-dependent developmental pathway essential for initiation and maintenance of cell division during postembryonic root development.
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Affiliation(s)
- T Vernoux
- Universiteit Gent, K.L. Ledeganckstraat 35, B-9000, Gent, Belgium
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Vernoux T, Wilson RC, Seeley KA, Reichheld JP, Muroy S, Brown S, Maughan SC, Cobbett CS, Van Montagu M, Inzé D, May MJ, Sung ZR. The ROOT MERISTEMLESS1/CADMIUM SENSITIVE2 gene defines a glutathione-dependent pathway involved in initiation and maintenance of cell division during postembryonic root development. Plant Cell 2000; 12:97-110. [PMID: 10634910 PMCID: PMC140217 DOI: 10.1105/tpc.12.1.97] [Citation(s) in RCA: 367] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/1999] [Accepted: 11/10/1999] [Indexed: 05/18/2023]
Abstract
Activation of cell division in the root apical meristem after germination is essential for postembryonic root development. Arabidopsis plants homozygous for a mutation in the ROOT MERISTEMLESS1 (RML1) gene are unable to establish an active postembryonic meristem in the root apex. This mutation abolishes cell division in the root but not in the shoot. We report the molecular cloning of the RML1 gene, which encodes the first enzyme of glutathione (GSH) biosynthesis, gamma-glutamylcysteine synthetase, and which is allelic to CADMIUM SENSITIVE2. The phenotype of the rml1 mutant, which was also evident in the roots of wild-type Arabidopsis and tobacco treated with an inhibitor of GSH biosynthesis, could be relieved by applying GSH to rml1 seedlings. By using a synchronized tobacco cell suspension culture, we showed that the G(1)-to-S phase transition requires an adequate level of GSH. These observations suggest the existence of a GSH-dependent developmental pathway essential for initiation and maintenance of cell division during postembryonic root development.
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Affiliation(s)
- T Vernoux
- Universiteit Gent, K.L. Ledeganckstraat 35, B-9000, Gent, Belgium
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Firbank LG, Dewar AM, Hill MO, May MJ, Perry JN, Rothery P, Squire GR, Woiwod IP. Farm-scale evaluation of GM crops explained. Nature 1999. [DOI: 10.1038/21516] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Affiliation(s)
- M J May
- Section of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520, USA
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Cobbett CS, May MJ, Howden R, Rolls B. The glutathione-deficient, cadmium-sensitive mutant, cad2-1, of Arabidopsis thaliana is deficient in gamma-glutamylcysteine synthetase. Plant J 1998; 16:73-78. [PMID: 9807829 DOI: 10.1046/j.1365-313x.1998.00262.x] [Citation(s) in RCA: 221] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This paper reports that the glutathione (GSH)-deficient mutant, cad2-1, of Arabidopsis is deficient in the first enzyme in the pathway of GSH biosynthesis, gamma-glutamylcysteine synthetase (GCS). The mutant accumulates a substrate of GCS, cysteine, and is deficient in the product, gamma-glutamylcysteine. In vitro enzyme assays showed that the cad2-1 mutant has 40% of wild-type levels of GCS activity but is unchanged in the activity of the second enzyme in the pathway, GSH synthetase. The CAD2 locus maps to chromosome 4 and is tightly linked to a gene, GSHA, identified by a previously isolated cDNA. A genomic clone of GSHA complements both the phenotypic and biochemical deficiencies of the cad2-1 mutant. The nucleotide sequence of the gene has been determined and, in the mutant, this gene contains a 6 bp deletion within an exon. These data demonstrate that the CAD2 gene encodes GCS. The cad2-1 mutation is close to the conserved cysteine which is believed to bind the substrate glutamate and the specific inhibitor L-buthionine-[S,R] sulfoximine (BSO). Both root growth and GCS activity of the cad2-1 mutant was less sensitive than the wild-type to inhibition by BSO, indicating that the mutation may alter the affinity of the inhibitor binding site.
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Affiliation(s)
- C S Cobbett
- Department of Genetics, University of Melbourne, Parkville, Australia.
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May MJ, Vernoux T, Sánchez-Fernández R, Van Montagu M, Inzé D. Evidence for posttranscriptional activation of gamma-glutamylcysteine synthetase during plant stress responses. Proc Natl Acad Sci U S A 1998; 95:12049-54. [PMID: 9751788 PMCID: PMC21763 DOI: 10.1073/pnas.95.20.12049] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Glutathione (GSH) is a key component of plant antioxidant defenses. We have sought to determine how the rate-limiting step in GSH biosynthesis, catalyzed by gamma-glutamylcysteine synthase (gammaECS) is regulated in Arabidopsis. Functional complementation of a yeast mutant deficient in this enzyme with an Arabidopsis expression library yielded two cDNAs with sequence identical to the previously described AtgammaECS. Nevertheless, the cellular concentration of GSH in these transformants was only 10% of wild-type concentrations and this was not a result of Cys availability. To explore the possibility that Arabidopsis gammaECS requires additional factors for full catalytic activity, we analyzed the GSH levels and the enzyme activities and transcript levels of both enzymes of the GSH biosynthetic pathway in Arabidopsis suspension cultures subjected to a variety of stresses that raise GSH levels. Our results demonstrate rapid posttranscriptional activation of Arabidopsis gammaECS. The implications of these findings for the mechanisms by which GSH concentrations are regulated during plant-stress responses are discussed.
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Affiliation(s)
- M J May
- Laboratorium voor Genetica, Department of Genetics, Flanders Interuniversity Institute for Biotechnology, Universiteit Gent, K.L. Ledeganckstraat 35, B-9000, Gent, Belgium
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Sánchez-Fernández R, Ardiles-Díaz W, Van Montagu M, Inzé D, May MJ. Cloning and expression analyses of AtMRP4, a novel MRP-like gene from Arabidopsis thaliana. Mol Gen Genet 1998; 258:655-62. [PMID: 9671034 DOI: 10.1007/s004380050779] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
In all organisms glutathione-conjugate transporters (GS-X pumps) mediate the detoxification of a number of xenobiotics by removing them from the cytosol. In addition, GS-X pumps appear to play a role in the processing of endogenous compounds. We have isolated a novel genomic clone from Arabidopsis thaliana that encodes a putative GS-X pump, AtMRP4, which is part of a recently defined gene family. The derived amino acid sequence shares high levels of similarity (55-63%) with human, yeast, and other Arabidopsis homologues. The expression of the different members of the AtMRP gene family in Arabidopsis cell suspensions after treatment with chemicals that modify glutathione metabolism (compounds that induce different types of stress and that act as herbicide antidotes- safeners- in monocotyledonous species) revealed that the members of this gene family are differentially regulated.
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Affiliation(s)
- R Sánchez-Fernández
- Department of Genetics, Flanders Interuniversity Institute of Biotechnology, Universiteit Gent, Belgium
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Abstract
The transcription factor NF-kappa B, more than a decade after its discovery, remains an exciting and active area of study. The involvement of NF-kappa B in the expression of numerous cytokines and adhesion molecules has supported its role as an evolutionarily conserved coordinating element in the organism's response to situations of infection, stress, and injury. Recently, significant advances have been made in elucidating the details of the pathways through which signals are transmitted to the NF-kappa B:I kappa B complex in the cytosol. The field now awaits the discovery and characterization of the kinase responsible for the inducible phosphorylation of I kappa B proteins. Another exciting development has been the demonstration that in certain situations NF-kappa B acts as an anti-apoptotic protein; therefore, elucidation of the mechanism by which NF-kappa B protects against cell death is an important goal. Finally, the generation of knockouts of members of the NF-kappa B/I kappa B family has allowed the study of the roles of these proteins in normal development and physiology. In this review, we discuss some of these recent findings and their implications for the study of NF-kappa B.
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Affiliation(s)
- S Ghosh
- Section of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
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May MJ, Wheeler-Jones CP, Houliston RA, Pearson JD. Activation of p42mapk in human umbilical vein endothelial cells by interleukin-1 alpha and tumor necrosis factor-alpha. Am J Physiol 1998; 274:C789-98. [PMID: 9530111 DOI: 10.1152/ajpcell.1998.274.3.c789] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Work from this and other laboratories has identified a role for protein tyrosine kinases in interleukin-1 alpha (IL-1 alpha)- and tumor necrosis factor-alpha (TNF-alpha)-induced responses in endothelial cells. In this study, we show that activation of human umbilical vein endothelial cells (HUVEC) by IL-1 alpha leads to increased tyrosine phosphorylation of several proteins including one with a molecular mass of approximately 42 kDa. This protein was identified as p42mapk by Western blot analysis. Tyrosine phosphorylation and catalytic activation of p42mapk by IL-1 alpha was transient, reaching maximal levels after 30 min and returning to basal levels by 120-300 min. Activation of p42mapk in HUVEC was also observed in response to TNF-alpha or to the protein kinase C (PKC)-activating phorbol ester phorbol 12-myristate 13-acetate (PMA). Pretreatment of HUVEC with IL-1 alpha or TNF-alpha prevented reactivation of p42mapk by either cytokine but did not affect subsequent activation in response to PMA. Activation of p42mapk by PMA was significantly reduced by the PKC inhibitor Ro-31-8220 and completely inhibited by the protein tyrosine kinase inhibitor genistein. Genistein, but not Ro-31-8220, attenuated IL-1 alpha- and TNF-alpha-induced p42mapk activation. Taken together, the results of this study demonstrate 1) that p42mapk is transiently activated in HUVEC by IL-1 alpha and TNF-alpha, 2) that this activation is PKC independent, and 3) that a genistein-inhibitable tyrosine kinase may be an upstream regulator of cytokine-induced p42mapk activation in human endothelium.
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Affiliation(s)
- M J May
- Vascular Biology Research Centre, King's College London, Kensington, London, United Kingdom
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Affiliation(s)
- M J May
- Section of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520, USA
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Abstract
Rel/NF-kappa B proteins constitute a family of structurally-related transcription factors that are regulated by interaction with a family of regulatory proteins, the I kappa B proteins. In this review, we will familiarize the reader with the known Rel/NF-kappa B and I kappa B molecules, and will discuss the types of interactions that occur between these proteins to regulate their function. In addition, we will describe what is known about the structure of Rel/NF-kappa B transcription complexes on DNA. Lastly, we will discuss the wide variety of biological stimuli and conditions which activate NF-kappa B and the genes whose expression are regulated by this family of transcription factors.
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Affiliation(s)
- M J May
- Section of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520, USA
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