12,599 research outputs found

    The onset of solar cycle 24: What global acoustic modes are telling us

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    We study the response of the low-degree, solar p-mode frequencies to the unusually extended minimum of solar surface activity since 2007. A total of 4768 days of observations collected by the space-based, Sun-as-a-star helioseismic GOLF instrument are analyzed. A multi-step iterative maximum-likelihood fitting method is applied to subseries of 365 days and 91.25 days to extract the p-mode parameters. Temporal variations of the l=0, 1, and 2 p-mode frequencies are then obtained from April 1996 to May 2009. While the p-mode frequency shifts are closely correlated with solar surface activity proxies during the past solar cycles, the frequency shifts of the l=0 and l=2 modes show an increase from the second half of 2007, when no significant surface activity is observable. On the other hand, the l=1 modes follow the general decreasing trend of the solar surface activity. The different behaviours between the l=0 and l=2 modes and the l=1 modes can be interpreted as different geometrical responses to the spatial distribution of the solar magnetic field beneath the surface of the Sun. The analysis of the low-degree, solar p-mode frequency shifts indicates that the solar activity cycle 24 started late 2007, despite the absence of activity on the solar surface.Comment: To be accepted by A&A (with minor revisions), 4 pages, 3 figures, 1 tabl

    Measurement of opaque film thickness

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    The theoretical and experimental framework for thickness measurements of thin metal films by low frequency thermal waves is described. Although it is assumed that the films are opaque and the substrates are comparatively poor thermal conductors, the theory is easily extended to other cases of technological interest. A brief description is given of the thermal waves and the experimental arrangement and parameters. The usefulness of the technique is illustrated for making absolute measurements of the thermal diffusivities of isotropic substrate materials. This measurement on pure elemental solids provides a check on the three dimensional theory in the limiting case of zero film thickness. The theoretical framework is then presented, along with numerical calculations and corresponding experimental results for the case of copper films on a glass substrate

    Systematic Literature Search for MSCR Thesis: Intrathecal Pain Pumps for the Treatment of Neuropathic Pain

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    This search strategy sought to construct an evidence-based position on the use of intrathecal pumps. We identified literature pertaining to the safety and efficacy of intrathecal pumps for the treatment of neuropathic pain. Articles obtained using this search strategy provided the background information for our thesis manuscript, which sought to determine if delivering opioids via the secure, non-tamperable intrathecal pain pump, in combination with other synergistic medications, would show improved pain scores and reduced side effects in patients with chronic neuropathic pain

    Electrophysiology Practice During COVID-19 Pandemic: A New York Tertiary Hospital Experience

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    © 2020 Elsevier Inc. As hospitals became overwhelmed during the Covid-19 pandemic in March-May in New York, Cardiology and Electrophysiology (EP) departments rapidly developed protocols for case selection as well modifying the practice of managing the cases. Recommendations by the AHA/HRS as well as American Society of Anesthesiology (ASA) were considered in the multidisciplinary collaborative approach to patient care and personnel safety and the anesthesiology team had an integral role in developing protocols for workflow, care, recovery and transport during these challenging times
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