19,796 research outputs found

    Inference of the ring current ion composition by means of charge exchange decay

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    The analysis of the measured ion fluxes during the several day storm recovery period and the assumption that beside hydrogen other ions were present and that the decays were exponential in nature, it was possible to establish three separate lifetimes for the ions. These fitted decay lifetimes are in excellent agreement with the expected charge exchange decay lifetimes for H(+), O(+), and He(+) in the energy and L-value range of the data. This inference technique, thus, establishes the presence of measurable and appreciable quantities of oxygen and helium ions as well as protons in the storm-time ring current. Indications that He(+) may also be present under these same conditions were found

    Motions of charged particles in the Magnetosphere under the influence of a time-varying large scale convection electric field

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    The motions of charged particles under the influence of the geomagnetic and electric fields were quite complex in the region of the inner magnetosphere. The Volland-Stern type large scale convection electric field was used successfully to predict both the plasmapause location and particle enhancements determined from Explorer 45 measurements. A time dependence in this electric field was introduced based on the variation in Kp for actual magnetic storm conditions. The particle trajectories were computed as they change in this time-varying electric field. Several storm fronts of particles of different magnetic moments were allowed to be injected into the inner magnetosphere from L = 10 in the equatorial plane. The motions of these fronts are presented in a movie format

    Local edge modes in doped cuprates with checkerboard polaronic heterogeneity

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    We study a periodic polaronic system, which exhibits a nanoscale superlattice structure, as a model for hole-doped cuprates with checkerboard-like heterogeneity, as has been observed recently by scanning tunneling microscopy (STM). Within this model, the electronic and phononic excitations are investigated by applying an unrestricted Hartree-Fock and a random phase approximation (RPA) to a multiband Peierls-Hubbard Hamiltonian in two dimensions

    Nucleosynthesis in Outflows from the Inner Regions of Collapsars

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    We consider nucleosynthesis in outflows originating from the inner regions of viscous accretion disks formed after the collapse of a rotating massive star. We show that wind-like outflows driven by viscous and neutrino heating can efficiently synthesize Fe-group elements moving at near-relativistic velocities. The mass of 56Ni synthesized and the asymptotic velocities attained in our calculations are in accord with those inferred from observations of SN1998bw and SN2003dh. These steady wind-like outflows are generally proton rich, characterized by only modest entropies, and consequently synthesize essentially nothing heavier than the Fe-group elements. We also discuss bubble-like outflows resulting from rapid energy deposition in localized regions near or in the accretion disk. These intermittent ejecta emerge with low electron fraction and are a promising site for the synthesis of the A=130 r-process peak elements.Comment: 35 pages, 6 figures, added discussion of the influence of nuclear recombination on wind dynamics, to appear in Ap

    Coherent Excitation of the 6S1/2 to 5D3/2 Electric Quadrupole Transition in 138Ba+

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    The electric dipole-forbidden, quadrupole 6S1/2 5D3/2 transition in Ba+ near 2051 nm, with a natural linewidth of 13 mHz, is attractive for potential observation of parity non-conservation, and also as a clock transition for a barium ion optical frequency standard. This transition also offers a direct means of populating the metastable 5D3/2 state to measure the nuclear magnetic octupole moment in the odd barium isotopes. Light from a diode-pumped, solid state Tm,Ho:YLF laser operating at 2051 nm is used to coherently drive this transition between resolved Zeeman levels in a single trapped 138Ba+ ion. The frequency of the laser is stabilized to a high finesse Fabry Perot cavity at 1025 nm after being frequency doubled. Rabi oscillations on this transition indicate a laser-ion coherence time of 3 ms, most likely limited by ambient magnetic field fluctuations.Comment: 5 pages, 5 figure

    The swept angle retarding mass spectrometer: Initial results from the Michigan auroral probe sounding rocket

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    Data from a sounding rocket flight of the swept angle retarding ion mass spectrometer (SARIMS) are presented to demonstrate the capability of the instrument to make measurements of thermal ions which are differential in angle, energy, and mass. The SARIMS was flown on the Michigan auroral probe over regions characterized first by discrete auroral arcs and later by diffuse precipitation. The instrument measured the temperature, densities, and flow velocities of the ions NO(+) and O(+). Measured NO(+) densities ranged from 10 to the 5th power up to 3 x 10 to the 5th power ions/cu cm, while the measured O(+) densities were a factor of 5-10 less. Ion temperatures ranged from 0.15 up to 0.33 eV. Eastward ion flows approximately 0.5 km/sec were measured near the arcs, and the observed flow magnitude decreased markedly inside the arcs

    Medicine-use evaluation of doxazosin prescribing to inform formulary recommendations

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    Background. It is estimated that >50% of all medicines are inappropriately prescribed, dispensed or sold. In 2018, the Western Cape Government Health (WCGH) Provincial Pharmacy and Therapeutics Committee (PPTC) endorsed an investigation of doxazosin use in provincial public sector healthcare facilities using a medicine-use evaluation (MUE). This was based on potential inappropriate prescribing, high usage and high costs associated with doxazosin.Objectives. To determine whether doxazosin was being prescribed in accordance with recommendations from standard treatment guidelines and essential medicines lists for hospital and primary healthcare level, as well as from the WCGH provincial code list.Methods. The study design consisted of a retrospective multicentre prescription review. The study population included all adult outpatients who were prescribed doxazosin, which was to be dispensed by the WCGH Chronic Dispensing Unit. Criteria for evaluation included indications for doxazosin administration and total daily dose prescribed.Results. The study sample comprised 171 patients. The main indication for doxazosin administration was as a fourth-line agent for the treatment of hypertension (82%). The remaining indications were not guideline approved (18%). The total daily doses identified were 4 mg (62%), followed by 8 mg (36%) and 2 mg (2%). All of these were approved dosages as per guideline recommendations.Conclusions. MUEs are an untapped resource for medication-use monitoring and practice improvement. MUEs offer a distinct, cost-effective approach to improve medicine use in all settings. This MUE revealed a relatively minor concern with doxazosin prescribing. MUEs can be beneficial to inform formulary changes and re-evaluate medication-use restrictions.
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