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  • 1
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    The influence of production mechanisms on pick-up ion loss at Mars (2013)
    Wiley
    Details
    Publication Date: 2013-02-02
    Description: [1]  This study quantifies the influence of ionization production mechanisms on ion escape and transport through near-Mars space. The Mars Test Particle simulation calculates the detailed ion velocity space distribution through a background magnetic and electric field model at specific locations. The main objective of this work is to extensively probe the sources of O + ion escape relative to the production mechanisms: photoionization, charge exchange, and electron impact. Seven production methods are explored and compared, resulting in total production and loss rates differing up to two orders of magnitude. Photoionization was compared as a function of solar zenith angle and optical shadow. Charge exchange O + production was studied with three methods: a constant rate assuming cold ion collisions, a constant rate proportional to the reaction cross-section and upstream solar wind bulk velocity, and finally a novel approach proportional to the cross-section and both the random and bulk velocity. Finally, electron impact ionization was considered as a constant and as a function of electron temperature. Of these methods, a baseline of the most physically relevant ion mechanisms was selected. Additionally, energy distributions at specific spatial locations highlight the individual ion populations in velocity space, revealing asymmetric and nongyrotropic features due to specific ionization methods. Analysis of the O + flux and loss is in agreement with observations and also indicates a strong polar plume in the northern hemisphere for a given interplanetary magnetic field orientation. We calculate the total production and escape to be 2.5 × 10 25 and 6.4 × 10 24 , respectively.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
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    Simulated kinetic effects of the corona and solar cycle on high altitude ion transport at Mars (2013)
    Wiley
    Details
    Publication Date: 2013-05-29
    Description: [1]  We present results from the Mars Test Particle simulation (MTP) as part of a community-wide model comparison in order to quantify the role of different neutral atmospheric conditions in planetary ion transport and escape. This study examines the effects of individual ion motion by simulating particle trajectories for three cases: solar minimum without the neutral corona, solar minimum with the inclusion of the neutral corona, and solar maximum with the inclusion of the neutral corona. The MTP simulates 1.5 billion test particles through background electric and magnetic fields computed by a global magnetohydrodynamic (MHD) model. By implementing virtual detectors in the simulation, the MTP has generated velocity space distributions of pick-up ions and quantifies the ion acceleration at different spatial locations. The study found that the inclusion of a hot neutral corona greatly affects the total O + production and subsequent loss, roughly doubling the total escape for solar minimum conditions and directly contributing to high energy sources above 10 keV. The solar cycle influences the amount of O + flux observed by the virtual detectors, increasing the O + flux and total escape by an order of magnitude from solar minimum to maximum. Additionally, solar maximum case induces greater mass loading of the magnetic fields, which decreases the gyroradius of the ions and redirects a significant ion population downtail to subsequently escape.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 3
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    Test particle comparison of heavy atomic and molecular ion distributions at Mars (2014)
    Wiley
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    Publication Date: 2014-03-06
    Description: [1]  This study uses the Mars Test Particle simulation to create virtual detections of O + , and in an orbital configuration in the Mars space environment. These atomic and molecular planetary pick-up ions are formed when the solar wind directly interacts with the neutral atmosphere, causing the ions to be accelerated by the background convective electric field. The subsequent ion escape is the subject of great interest, specifically with respect to which species dominates ion loss from Mars. O + is found to be the dominant escaping ion because of the large sources of transported ions in the low energy (〈10 eV) and high energy (〉1 keV) range. and are observed at these energy ranges but with much lower fluxes and are generally only found in the tail between 10 eV and 1 keV. Using individual particle traces, we reveal the origin and trajectories of the low energy downtail O + populations and high energy polar O + populations that contribute to the total escape. Comparing them against and reveals that the extended hot oxygen corona contributes to source regions of high and low energy escaping ions. Additionally, we present results for solar minimum and maximum conditions with respect to ion fluxes and energies in order to robustly describe the physical processes controlling planetary ion distributions and atmospheric escape.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 4
    Electronic Resource
    Electronic Resource
    Steam explosion of mixed hardwood chips, rice hulls, corn stalks, and sugar cane bagasse (1984)
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 32 (1984), S. 1166-1172 
    Details
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jf00125a058
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    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Rapid determination of lignocellulose by diffuse reflectance Fourier transform infrared spectrometry (1985)
    s.l. : American Chemical Society
    Analytical chemistry 57 (1985), S. 2867-2869 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00291a027
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    Paper (German National Licenses)
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  • 6
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    Global climate evolution during the last deglaciation [Earth, Atmospheric, and Planetary Sciences] (2012)
    National Academy of Sciences
    Details
    Publication Date: 2012-05-09
    Description: Deciphering the evolution of global climate from the end of the Last Glacial Maximum approximately 19 ka to the early Holocene 11 ka presents an outstanding opportunity for understanding the transient response of Earth’s climate system to external and internal forcings. During this interval of global warming, the decay of ice sheets caused global mean sea level to rise by approximately 80 m; terrestrial and marine ecosystems experienced large disturbances and range shifts; perturbations to the carbon cycle resulted in a net release of the greenhouse gases CO2 and CH4 to the atmosphere; and changes in atmosphere and ocean circulation affected the global distribution and fluxes of water and heat. Here we summarize a major effort by the paleoclimate research community to characterize these changes through the development of well-dated, high-resolution records of the deep and intermediate ocean as well as surface climate. Our synthesis indicates that the superposition of two modes explains much of the variability in regional and global climate during the last deglaciation, with a strong association between the first mode and variations in greenhouse gases, and between the second mode and variations in the Atlantic meridional overturning circulation.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 7
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    Martian planetary heavy ion sputtering of Phobos (2014)
    Wiley
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    Publication Date: 2014-08-30
    Description: The Martian moons, Phobos and Deimos, have long been suspected to be the sources of tenuous neutral gas tori encircling Mars. While direct outgassing has been ruled out as a strong source, micrometeoroid impact vaporization and charged particle sputtering must operate based on observations at other airless bodies. Previous models have addressed solar wind sputtering of Phobos, however, Phobos and Deimos are also subject to a significant, yet temporally variable, flux of heavy planetary ions escapingfrom Mars. In this report, we use a combination MHD / test-particle model to calculate the planetary heavy ion flux to Phobos and the ensuing neutral sputtered flux. Depending on ambient solar wind conditions and the location of Phobos, heavy ion sputtering of Phobos generates neutral fluxes up to and exceeding that from solar wind sputtering. We model pick-up ions from the Phobos torus itself with applications for observations by the upcoming MAVEN mission.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 8
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    Nutraceuticals (1999)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1999-12-28
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Curry, M -- Hazard-Daniel, A -- Daniel, H J -- New York, N.Y. -- Science. 1999 Dec 3;286(5446):1854-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10610573" target="_blank"〉PubMed〈/a〉
    Keywords: *Dietary Supplements/adverse effects ; Drug Prescriptions ; Drug-Related Side Effects and Adverse Reactions ; *Legislation, Drug ; *Legislation, Food ; United States ; United States Food and Drug Administration
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 9
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    Magnetic Topology Response to the 2003 Halloween ICME Event at Mars (2019)
    Wiley
    Details
    Publication Date: 2019
    Description: Abstract Understanding how the Mars plasma environment responds to space weather events provides insights into the early Sun‐Mars interaction and helps constrain the extrapolation of atmospheric loss back in time. The 2003 Halloween interplanetary coronal mass ejection (ICME) event is one of the most extreme space weather events encountered by Mars during the last two decades. Mars Global Surveyor's circular orbit at ∼400 km allows us to observationally study the magnetic topology response to this extreme event globally for the first time. We analyze the suprathermal electron data and magnetic field measurements from Mars Global Surveyor to infer magnetic topology before, during, and after this ICME event and quantify the variation of the topology over both weak and strong crustal regions and correlate the variation with the upstream dynamic pressure. Over weak crustal regions, more draped field lines and fewer closed field lines are observed under high dynamic pressures, implying a deeper interplanetary magnetic field penetration during the ICME event. Over dayside strong crustal regions, the dominant magnetic topology switches from closed field lines during quiet periods to open field lines during disturbed periods, suggesting more reconnection occurring between the crustal magnetic fields and interplanetary magnetic field. This mixed magnetic topological response is consistent with predictions from magnetohydrodynamic simulations for ICME events in previous studies.
    Print ISSN: 2169-9380
    Electronic ISSN: 2169-9402
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 10
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    The Phobos neutral and ionized torus (2016)
    Wiley
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    Publication Date: 2016-04-26
    Description: Charged-particle sputtering, micrometeoroid impact vaporization, and photon-stimulated desorption are fundamental processes operating at airless surfaces throughout the solar system. At larger bodies, such as Earth's Moon and several of the outer planet moons, these processes generate tenuous surface-bound exospheres that have been observed by a variety of methods. Phobos and Deimos, in contrast, are too gravitationally weak to keep ejected neutrals bound and thus, are suspected to generate neutral tori in orbit around Mars. While these tori have not yet been detected, the distribution and density of both the neutral and ionized components are of fundamental interest. We combine a neutral Monte Carlo model and a hybrid plasma model to investigate both the neutral and ionized components of the Phobos torus. We show that the spatial distribution of the neutral torus is highly dependent on each individual species (due to ionization rates that span nearly four orders-of-magnitude) and on the location of Phobos with respect to Mars. Additionally, we present the flux distribution of torus pick-up ions throughout the Martian system and estimate typical pick-up ion fluxes. We find that the predicted pick-up ion fluxes are too low to perturb the ambient plasma, consistent with previous null detections by spacecraft around Mars.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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