1,165 research outputs found

    Jupiter's polar ionospheric flows: measured intensity and velocity variations poleward of the main auroral oval

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    Recent analysis of high-resolution spectra of Doppler-shifted H3+ emission from the auroral/polar regions of Jupiter revealed a complex wind system, with a persistent auroral electrojet and strong anti-sunward flows in a region of lesser intensity centred around the magnetic pole [ Stallard et al., 2001 ]. This region, which we have called the Dark Polar Region (DPR), is re-investigated, transforming the observed line-of-sight velocities into a frame of reference fixed with respect to the magnetic pole. The DPR is shown to include a region essentially stagnant in this frame of reference (the f-DPR). We identify it as a region coupled to open magnetotail field lines. There is also a transition region in which the ion velocity returns to corotation (the r-DPR)

    Seasonal Variability In The Ionosphere Of Uranus

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    Infrared ground-based observations using IRTF, UKIRT, and Keck II of Uranus have been analyzed as to identify the long-term behavior of the H-3(+) ionosphere. Between 1992 and 2008 there are 11 individual observing runs, each recording emission from the H-3(+) Q branch emission around 4 mu m through the telluric L' atmospheric window. The column-averaged rotational H-3(+) temperature ranges between 715 K in 1992 and 534 K in 2008, with the linear fit to all the run-averaged temperatures decreasing by 8 K year(-1). The temperature follows the fractional illumination curve of the planet, declining from solstice (1985) to equinox (2007). Variations in H-3(+) column density do not appear to be correlated to either solar cycle phase or season. The radiative cooling by H-3(+) is similar to 10 times larger than the ultraviolet solar energy being injected to the atmosphere. Despite the fact that the solar flux alone is incapable of heating the atmosphere to the observed temperatures, the geometry with respect to the Sun remains an important driver in determining the thermospheric temperature. Therefore, the energy source that heats the thermosphere must be linked to solar mechanisms. We suggest that this may be in the form of conductivity created by solar ionization of atmospheric neutrals and/or seasonally dependent magnetospherically driven current systems.STFC PP/E/000983/1, ST/G0022223/1RCUKGemini ObservatoryNational Aeronautics and Space Administration (NASA) NXX08A043G, NNX08AE38AAstronom

    Adaptive clinical trials incorporating treatment selection and evaluation: methodology and application in progressive multiple sclerosis

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    In progressive multiple sclerosis (MS) irreversible disability often takes many years to accumulate as a result prolonged trials are required to assess the benefits of therapies. There is a need to understand the relationship between short-term outcome measures such as MRI endpoints and long-term clinical outcomes in progression to determine the evolution of the disease early on. Thus, the common phase I-II-III paradigm for clinical trial design with separate trials for each phase may not be appropriate
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