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  • 1
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    Ionosphere-Magnetosphere Energy Interplay in the Regions of Diffuse Aurora (2016)
    Wiley
    Details
    Publication Date: 2016-07-10
    Description: Both electron cyclotron harmonic (ECH) waves and whistler mode chorus waves resonate with electrons of the Earth's plasma sheet in the energy range from 10s eV to several keV and produce the electron diffuse aurora at ionospheric altitudes. Interaction of these superthermal electrons with the neutral atmosphere leads to the production of secondary electrons (E 〈 500-600 eV) and, as a result, leads to the activation of lower energy superthermal electron spectra that can escape back to the magnetosphere and contribute to the thermal electron energy deposition processes in the magnetospheric plasma. The ECH and whistler mode chorus waves, however, can also interact with the secondary electrons that are coming from both of the magnetically conjugated ionospheres after they have been produced by initially precipitated high energy electrons that came from the plasma sheet. After their degradation and subsequent reflection in magnetically conjugate atmospheric regions, both the secondary electrons and the precipitating electrons with high (E 〉 600 eV) initial energies will travel back through the loss cone, become trapped in the magnetosphere, and redistribute the energy content of the magnetosphere-ionosphere system. Thus scattering of the secondary electrons by ECH and whistler mode chorus waves leads to an increase of the fraction of superthermal electron energy deposited into the core magnetospheric plasma.
    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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    Source of the Bursty Bulk Flow Diffuse Aurora: Electrostatic Cyclotron Harmonic and Whistler Waves in the Coupling of Bursty Bulk Flows to Auroral Precipitation (2019)
    Wiley
    Details
    Publication Date: 2019
    Description: Abstract Electron cyclotron harmonic (ECH) and whistler chorus waves are recognized as the two mechanisms responsible for the resonant wave‐particle interactions necessary to precipitate plasma sheet electrons into the ionosphere, producing the diffuse Aurora. Previous work has demonstrated ECH waves dominate electron scattering at L shells 〉8, while whistler chorus dominates scattering at L shells L 〈 8. However, we find from Time History of Events and Macroscale (THEMIS) Interactions during Substorms observations of fast flows at L = 12 that oblique whistler chorus emissions play the dominant role in scattering electrons. Previous works have identified whistler‐mode waves within fast flows that are produced by an electron temperature anisotropy Te,⊥/Te,||〉 1, consistent with electron betatron acceleration. Here, however, we find whistler chorus emissions throughout an interval of fast flows where Te,⊥/Te,||〈 1. Parallel electron beams account for the enhanced parallel electron temperature and serve as the instability mechanism for the whistler chorus. The parallel electron beams and associated cigar‐shaped distributions are consistent with Fermi acceleration at dipolarizations in fast flows. We demonstrate that the scattering efficiency of the whistler chorus exceeds that of ECH waves, which THEMIS also detects during the fast flows. The obliquity of the whistler waves permits efficient scattering of lower‐energy electrons into the diffuse aurora. We conclude that Fermi acceleration of electrons provides one important free‐energy source for the wave‐particle interactions responsible for coupling plasma sheet electrons into the diffuse aurora during substorm conditions.
    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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  • 3
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    Electron distribution function formation in regions of diffuse aurora (2015)
    Wiley
    Details
    Publication Date: 2015-10-22
    Description: The precipitation of high-energy magnetospheric electrons ( E ∼ 600eV-10KeV) in the diffuse aurora contributes significant energy flux into the Earth's ionosphere. To fully understand the formation of this flux at the upper ionospheric boundary, ∼700-800 km, it is important to consider the coupled ionosphere-magnetosphere system. In the diffuse aurora, precipitating electrons initially injected from the plasma sheet via wave-particle interaction processes degrade in the atmosphere toward lower energies and produce secondary electrons via impact ionization of the neutral atmosphere. These precipitating electrons can be additionally reflected upward from the two conjugate ionospheres, leading to a series of multiple reflections through the magnetosphere. These reflections greatly influence the initially precipitating flux at the upper ionospheric boundary (700-800 km) and the resultant population of secondary electrons and electrons cascading toward lower energies. In this paper, we present the solution of the Boltzman-Landau kinetic equation that uniformly describes the entire electron distribution function in the diffuse aurora, including the affiliated production of secondary electrons ( E 〈 600eV) and its energy interplay in the magnetosphere and two conjugated ionospheres. This solution takes into account, for the first time, the formation of the electron distribution function in the diffuse auroral region, beginning with the primary injection of plasma sheet electrons via both electrostatic electron cyclotron harmonic waves and whistler mode chorus waves to the loss cone, and including their subsequent multiple atmospheric reflections in the two magnetically conjugated ionospheres. It is demonstrated that magnetosphere-ionosphere coupling is key in forming the electron distribution function in the diffuse auroral region.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 4
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    Superthermal Electron Magnetosphere-Ionosphere Coupling in the Diffuse Aurora in the Presence of ECH Waves (2015)
    Wiley
    Details
    Publication Date: 2015-01-02
    Description: There are two main theories for the origin of the diffuse auroral electron precipitation: first, pitch angle scattering by electrostatic electron cyclotron harmonic (ECH) waves and second, by whistler mode waves. Precipitating electrons initially injected from the plasmasheet to the loss-cone via wave-particle interaction processes degrade in the atmosphere toward lower energies and produce secondary electrons via impact ionization of the neutral atmosphere. These secondary electrons can escape back to the magnetosphere, become trapped on closed magnetic field lines, and deposit their energy back to the inner magnetosphere. ECH and whistler mode waves can also move electrons in the opposite direction, from the loss cone into the trap zone, if the source of such electrons exists in conjugate ionospheres located at the same field lines as the trapped magnetospheric electron population. Such a situation exists in the simulation scenario of Superthermal Electron (SE) energy interplay in the region of diffuse aurora presented and discussed by Khazanov et al. [2014] and will be quantified in this paper by taking into account the interaction of secondary electrons with ECH waves.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 5
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    Charge transport in amorphous InGaZnO thin-film transistors (2012)
    American Physical Society (APS)
    Details
    Publication Date: 2012-10-27
    Description: Author(s): W. Chr. Germs, W. H. Adriaans, A. K. Tripathi, W. S. C. Roelofs, B. Cobb, R. A. J. Janssen, G. H. Gelinck, and M. Kemerink We investigate the mechanism of charge transport in indium gallium zinc oxide (a-IGZO), an amorphous metal-oxide semiconductor. We measured the field-effect mobility and the Seebeck coefficient ( S = Δ V / Δ T ) of a-IGZO in thin-film transistors as a function of charge-carrier density for different tempera... [Phys. Rev. B 86, 155319] Published Fri Oct 26, 2012
    Keywords: Semiconductors II: surfaces, interfaces, microstructures, and related topics
    Print ISSN: 1098-0121
    Electronic ISSN: 1095-3795
    Topics: Physics
    Published by American Physical Society (APS)
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  • 6
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    Chemical genetics of Plasmodium falciparum (2010)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2010-05-21
    Description: Malaria caused by Plasmodium falciparum is a disease that is responsible for 880,000 deaths per year worldwide. Vaccine development has proved difficult and resistance has emerged for most antimalarial drugs. To discover new antimalarial chemotypes, we have used a phenotypic forward chemical genetic approach to assay 309,474 chemicals. Here we disclose structures and biological activity of the entire library-many of which showed potent in vitro activity against drug-resistant P. falciparum strains-and detailed profiling of 172 representative candidates. A reverse chemical genetic study identified 19 new inhibitors of 4 validated drug targets and 15 novel binders among 61 malarial proteins. Phylochemogenetic profiling in several organisms revealed similarities between Toxoplasma gondii and mammalian cell lines and dissimilarities between P. falciparum and related protozoans. One exemplar compound displayed efficacy in a murine model. Our findings provide the scientific community with new starting points for malaria drug discovery.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2874979/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2874979/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Guiguemde, W Armand -- Shelat, Anang A -- Bouck, David -- Duffy, Sandra -- Crowther, Gregory J -- Davis, Paul H -- Smithson, David C -- Connelly, Michele -- Clark, Julie -- Zhu, Fangyi -- Jimenez-Diaz, Maria B -- Martinez, Maria S -- Wilson, Emily B -- Tripathi, Abhai K -- Gut, Jiri -- Sharlow, Elizabeth R -- Bathurst, Ian -- El Mazouni, Farah -- Fowble, Joseph W -- Forquer, Isaac -- McGinley, Paula L -- Castro, Steve -- Angulo-Barturen, Inigo -- Ferrer, Santiago -- Rosenthal, Philip J -- Derisi, Joseph L -- Sullivan, David J -- Lazo, John S -- Roos, David S -- Riscoe, Michael K -- Phillips, Margaret A -- Rathod, Pradipsinh K -- Van Voorhis, Wesley C -- Avery, Vicky M -- Guy, R Kiplin -- AI045774/AI/NIAID NIH HHS/ -- AI053680/AI/NIAID NIH HHS/ -- AI067921/AI/NIAID NIH HHS/ -- AI075517/AI/NIAID NIH HHS/ -- AI075594/AI/NIAID NIH HHS/ -- AI080625/AI/NIAID NIH HHS/ -- AI082617/AI/NIAID NIH HHS/ -- AI28724/AI/NIAID NIH HHS/ -- AI35707/AI/NIAID NIH HHS/ -- AI53862/AI/NIAID NIH HHS/ -- AI772682/AI/NIAID NIH HHS/ -- CA78039/CA/NCI NIH HHS/ -- F32 AI077268/AI/NIAID NIH HHS/ -- F32 AI077268-03/AI/NIAID NIH HHS/ -- P01 AI035707/AI/NIAID NIH HHS/ -- P01 AI035707-140007/AI/NIAID NIH HHS/ -- P01 CA078039-10/CA/NCI NIH HHS/ -- P41 RR001614/RR/NCRR NIH HHS/ -- P41 RR001614-246970/RR/NCRR NIH HHS/ -- R01 AI045774/AI/NIAID NIH HHS/ -- R01 AI045774-09/AI/NIAID NIH HHS/ -- R37 AI028724/AI/NIAID NIH HHS/ -- R37 AI028724-17/AI/NIAID NIH HHS/ -- R56 AI082617/AI/NIAID NIH HHS/ -- R56 AI082617-01/AI/NIAID NIH HHS/ -- U01 AI053862/AI/NIAID NIH HHS/ -- U01 AI053862-05/AI/NIAID NIH HHS/ -- U01 AI075594-03/AI/NIAID NIH HHS/ -- UL1 TR000005/TR/NCATS NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2010 May 20;465(7296):311-5. doi: 10.1038/nature09099.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemical Biology and Therapeutics, St Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20485428" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antimalarials/*analysis/isolation & purification/*pharmacology ; Cell Line ; *Drug Discovery ; Drug Evaluation, Preclinical ; Drug Resistance/drug effects ; Drug Therapy, Combination ; Erythrocytes/drug effects/parasitology ; Humans ; Malaria, Falciparum/drug therapy/parasitology ; Mice ; Phenotype ; Phylogeny ; Plasmodium falciparum/*drug effects/*genetics/metabolism ; Reproducibility of Results ; Small Molecule Libraries/chemistry/pharmacology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 7
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    Banded structures in electron pitch angle diffusion coefficients from resonant wave-particle interactions (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-04-05
    Description: Electron pitch angle (D αα ) and momentum (D pp ) diffusion coefficients have been calculated due to resonant interactions with electrostatic electron cyclotron harmonic (ECH) and whistler mode chorus waves. Calculations have been performed at two spatial locations L = 4.6 and 6.8 for electron energies ≤10 keV. Landau (n = 0) resonance and cyclotron harmonic resonances n = ±1, ±2, … ±5 have been included in the calculations. It is found that diffusion coefficient versus pitch angle (α) profiles show large dips and oscillations or banded structures. The structures are more pronounced for ECH and lower band chorus (LBC) and particularly at location 4.6. Calculations of diffusion coefficients have also been performed for individual resonances. It is noticed that the main contribution of ECH waves in pitch angle diffusion coefficient is due to resonances n = +1 and n = +2. A major contribution to momentum diffusion coefficients appears from n = +2. However, the banded structures in D αα and D pp coefficients appear only in the profile of diffusion coefficients for n = +2. The contribution of other resonances to diffusion coefficients is found to be, in general, quite small or even negligible. For LBC and upper band chorus waves, the banded structures appear only in Landau resonance. The D pp diffusion coefficient for ECH waves is one to two orders smaller than D αα coefficients. For chorus waves, D pp coefficients are about an order of magnitude smaller than D αα coefficients for the case n ≠ 0. In case of Landau resonance, the values of D pp coefficient are generally larger than the values of D αα coefficients particularly at lower energies. As an aid to the interpretation of results, we have also determined the resonant frequencies. For ECH waves, resonant frequencies have been estimated for wave normal angle 89° and harmonic resonances n = +1, +2, and +3, whereas for whistler mode waves, the frequencies have been calculated for angle 10° and Landau resonance. Further, in ECH waves, the banded structures appear for electron energies ≥1 keV, and for whistler mode chorus waves, structures appear for energies 〉2 keV at L = 4.6 and above 200 eV for L = 6.8. The results obtained in the present work will be helpful in the study of diffusion curves and will have important consequences for diffuse aurora and pancake distributions.
    Print ISSN: 1070-664X
    Electronic ISSN: 1089-7674
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 8
    Electronic Resource
    Electronic Resource
    Thermoelectret state in polyvinyl chloride : polyethylene polyblends (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 2031-2033 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thermoelectrets of polyvinyl chloride (PVC)–polyethylene blends were prepared and their thermally stimulated discharge current was studied. The results are discussed in terms of space charge that leads to induced dipole formation. The results indicate that the contribution of PVC dipoles to the total polarization of polyblend thermoelectrets is either insignificant, or is masked by the space-charge polarization that leads to induced dipole formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341734
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  • 9
    Electronic Resource
    Electronic Resource
    Development of a sealed-off cw CO2 laser using a supported gold catalyst (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3853-3855 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A compact low-power long-life sealed-off cw CO2 laser has been developed by incorporating a catalyst-coated outer jacket that helps to regenerate CO2 from the dissociation products formed during discharge. Maintaining the catalyst at an optimized temperature prevented CO2 adsorption in its bulk and resulted in the required level of CO oxidation activity. The laser system has been operated during the day for the past five months at a constant output level of about 4 W. The gas analysis performed at different catalyst temperatures suggests that although the presence of CO in large amounts is detrimental, an optimum concentration of carbon monoxide supports the CO2 laser operation. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145177
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of nonionic solutes on the freezing potential of dilute ionic aqueous solutions (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 1404-1405 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Experiments are described which show that sucrose considerably reduces the freezing potential of very dilute solutions of alkali halides, NH4Cl and (NH4)2CO3 while urea enhances the magnitude of such potentials. Results have been explained on the basis of a hypothetical model based on nonequilibrium structure of ice containing hydrogen bonded structure and free water molecules in which foreign ions are incorporated during freezing and the growth of phase occurs by the acquisition of hydronium and hydroxyl ions which form free water molecules in the nonequilibrium ice phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.449406
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