23,161 research outputs found

    Direct observations in the dusk hours of the characteristics of the storm-time ring current particles during the beginning of magnetic storms

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    The characteristic features of the initial enhancement of the storm-time ring current particles in the evening hours are consistent with flow patterns resulting from a combination of inward convection, gradient drift, and corotation which carries plasma sheet protons into low L-values near midnight and the higher energy proton component into the plasmasphere and through the evening hours. Data from four magnetic storms during the early life of Explorer 45, when the local time of apogee was in the afternoon and evening hours, show that protons with lower magnetic moments penetrate deeper into the magnetosphere until a low limit, determined by the corotation and gradient drift forces, is reached. Such particle motions produce the stable energy dependent inner boundary of the ring current protons inside the plasmapause in the dusk sector and also provide the mechanism for energy injection into the ring current region. From the analyses of the pitch angle distributions it is evident that charge exchange and wave particle interactions are not the dominant causes of this inner boundary

    Ring current proton decay by charge exchange

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    Explorer 45 measurements during the recovery phase of a moderate magnetic storm have confirmed that the charge exchange decay mechanism can account for the decay of the storm-time proton ring current. Data from the moderate magnetic storm of 24 February 1972 was selected for study since a symmetrical ring current had developed and effects due to asymmetric ring current losses could be eliminated. It was found that after the initial rapid decay of the proton flux, the equatorially mirroring protons in the energy range 5 to 30 keV decayed throughout the L-value range of 3.5 to 5.0 at the charge exchange decay rate calculated by Liemohn. After several days of decay, the proton fluxes reached a lower limit where an apparent equilibrium was maintained, between weak particle source mechanisms and the loss mechanisms, until fresh protons were injected into the ring current region during substorms. While other proton loss mechanisms may also be operating, the results indicate that charge exchange can entirely account for the storm-time proton ring current decay, and that this mechanism must be considered in all studies involving the loss of proton ring current particles

    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

    Real-Time Operating System/360

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    RTOS has a cost savings advantage for real-time applications, such as those with random inputs requiring a flexible data routing facility, display systems simplified by a device independent interface language, and complex applications needing added storage protection and data queuing

    Image-based Recommendations on Styles and Substitutes

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    Humans inevitably develop a sense of the relationships between objects, some of which are based on their appearance. Some pairs of objects might be seen as being alternatives to each other (such as two pairs of jeans), while others may be seen as being complementary (such as a pair of jeans and a matching shirt). This information guides many of the choices that people make, from buying clothes to their interactions with each other. We seek here to model this human sense of the relationships between objects based on their appearance. Our approach is not based on fine-grained modeling of user annotations but rather on capturing the largest dataset possible and developing a scalable method for uncovering human notions of the visual relationships within. We cast this as a network inference problem defined on graphs of related images, and provide a large-scale dataset for the training and evaluation of the same. The system we develop is capable of recommending which clothes and accessories will go well together (and which will not), amongst a host of other applications.Comment: 11 pages, 10 figures, SIGIR 201

    Meanders and the Temperley-Lieb algebra

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    The statistics of meanders is studied in connection with the Temperley-Lieb algebra. Each (multi-component) meander corresponds to a pair of reduced elements of the algebra. The assignment of a weight qq per connected component of meander translates into a bilinear form on the algebra, with a Gram matrix encoding the fine structure of meander numbers. Here, we calculate the associated Gram determinant as a function of qq, and make use of the orthogonalization process to derive alternative expressions for meander numbers as sums over correlated random walks.Comment: 85p, uuencoded, uses harvmac (l mode) and epsf, 88 figure

    Ring current particle distributions during the magnetic storms of 16-18 December 1971

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    In an effort to summarize the constrasting development of the stormtime ring currents during the December 16-18, 1971 magnetic storms, maps were drawn indicating the proton energy density spatial/temporal distributions. The maps contain distributions for the 5 to 138 keV protons for each of seven orbits. The first storm was not characteristic of a single substorm nor a fully developed magnetic storm, but it was comprised of a sudden commencement, a positive phase, and multiple substorms producing a small depression in the magnetic field. The second storm was classical in development with a short two hour growth phase. Energy density distribution constrasts for the two storms show the second storm displayed three dominant features over the first storm. They were: (1) the intensities were 2 1/2 times larger, (2) the depths of penetration were 1/2 to 1 Reynolds number lower, and (3) the distribution became symmetric

    EXAMINATION OF GLUTEAL MUSCLE FIRING and KINETICS OF THE LOWER EXTREMITY DURING THE WINDMILL SOFTBALL PITCH

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    The purpose of this study was to examine the muscle activation and kinetic data of the lower extremity during the windmill softball pitch. Limited research has documented the lower extremity in the windmill softball pitch. Seven female post-pubescent softball players volunteered for the study. Pitchers were analyzed with surface electromyography and motion analysis software. There was no relationship observed between gluteal activation and ground reaction forces at SFP and maximum force. Only one investigation prior to this study reported ground reaction forces of windmill softball pitchers, however they did not examine the EMG activity

    Long-term Variability of H2_2CO Masers in Star-forming Regions

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    We present results of a multi-epoch monitoring program on variability of 6\,cm formaldehyde (H2_2CO) masers in the massive star forming region NGC\,7538\,IRS\,1 from 2008 to 2015 conducted with the GBT, WSRT, and VLA. We found that the similar variability behaviors of the two formaldehyde maser velocity components in NGC\,7538\,IRS\,1 (which was pointed out by Araya and collaborators in 2007) have continued. The possibility that the variability is caused by changes in the maser amplification path in regions with similar morphology and kinematics is discussed. We also observed 12.2\,GHz methanol and 22.2\,GHz water masers toward NGC\,7538\,IRS\,1. The brightest maser components of CH3_3OH and H2_2O species show a decrease in flux density as a function of time. The brightest H2_2CO maser component also shows a decrease in flux density and has a similar LSR velocity to the brightest H2_2O and 12.2\,GHz CH3_3OH masers. The line parameters of radio recombination lines and the 20.17 and 20.97\,GHz CH3_3OH transitions in NGC\,7538\,IRS\,1 are also reported. In addition, we observed five other 6\,cm formaldehyde maser regions. We found no evidence of significant variability of the 6\,cm masers in these regions with respect to previous observations, the only possible exception being the maser in G29.96-0.02. All six sources were also observed in the H213_2^{13}CO isotopologue transition of the 6\,cm H2_2CO line; H213_2^{13}CO absorption was detected in five of the sources. Estimated column density ratios [H212_2^{12}CO]/[H213_2^{13}CO] are reported.Comment: 29 pages, 9 figure
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