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  • 1
    Electronic Resource
    Electronic Resource
    The "injection problem" for quasiparallel shocks (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 4560-4576 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For a particle to be accelerated diffusively at a shock by the first-order Fermi acceleration mechanism, the particle must be sufficiently energetic that it can scatter across all the micro- and macrostructure of the shock, experiencing compression between the converging upstream and downstream states. This is the well-known "injection problem." Here the interaction of ions with the ramp of a quasiparallel shock is investigated. Some ions incident on the shock experience specular reflection, caused either by the cross-shock electrostatic potential or by mirroring as the magnetic field is bent and compressed through the ramp. Scattering of reflected ions by self-generated and pre-existing turbulence in the region upstream of the shock then acts to trap backstreaming ions and return them to the ramp, where some experience further reflections. Such repeated reflections and scattering energize a subpopulation of ions up to energies sufficiently large that they can be diffusively shock accelerated. Two ion distributions are considered: pickup ions which are assumed to be described by a shell distribution, are thermal solar wind ions which may be described by a kappa distribution. Injection efficiencies are found analytically to be very high for pickup ions and much lower for thermal solar wind ions, suggesting that this injection mechanism, stochastic reflected ion or SRI acceleration, is a natural precursor for the acceleration of the anomalous cosmic ray component at a quasiparallel shock. While significantly less efficient, SRI acceleration is also viable for thermal solar wind ions described by a kappa distribution. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1400125
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Global Processes that Determine Cosmic Ray Modulation (1998)
    Springer
    Space science reviews 83 (1998), S. 179-214 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The global processes that determine cosmic ray modulation are reviewed. The essential elements of the theory which describes cosmic ray behavior in the heliosphere are summarized, and a series of discussions is presented which compare the expectations of this theory with observations of the spatial and temporal behavior of both galactic cosmic rays and the anomalous component; the behavior of cosmic ray electrons and ions; and the 26-day variations in cosmic rays as a function of heliographic latitude. The general conclusion is that the current theory is essentially correct. There is clear evidence, in solar minimum conditions, that the cosmic rays and the anomalous component behave as is expected from theory, with strong effects of gradient and curvature drifts. There is strong evidence of considerable latitude transport of the cosmic rays, at all energies, but the mechanism by which this occurs is unclear. Despite the apparent success of the theory, there is no single choice for the parameters which describe cosmic ray behavior, which can account for all of the observed temporal and spatial variations, spectra, and electron vs. ion behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005074923940
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    Paper (German National Licenses)
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  • 3
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    Response to "When will physical activity be routinely measured in the clinical setting? The case for bariatric surgery" (2016)
    Oxford University Press
    Details
    Publication Date: 2016-08-10
    Print ISSN: 0895-7061
    Electronic ISSN: 1879-1905
    Topics: Medicine
    Published by Oxford University Press
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  • 4
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    Predictors of Hypertension Remission and Recurrence After Bariatric Surgery (2016)
    Oxford University Press
    Details
    Publication Date: 2016-04-13
    Description: BACKGROUND Few data exist on factors associated with hypertension (HTN) remission post-bariatric surgery. No information on factors that may predict HTN relapse is available. The aims were to assess the HTN remission and relapse rates at 1 and 3 years, respectively, post-bariatric surgery, and determine predictive factors. METHODS A nonrandomized prospective cohort study on severely obese patients undergoing laparoscopic Roux-en-Y gastric bypass (LRYGB) or laparoscopic sleeve gastrectomy (LSG) with a follow-up of 36 months was conducted between 2005 and 2011. Criteria for HTN diagnosis were current treatment with antihypertensive agents and/or systolic blood pressure (BP) 〉140mm Hg and/or diastolic BP 〉90mm Hg. HTN remission was defined as normalization of BP maintained after discontinuation of medical treatment. RESULTS A total of 197 patients were included in the study. HTN was present in 47.7%; 68.1% of hypertensive patients showed HTN remission 1 year after the surgical procedure, 21.9% of whom had relapsed at 3 years. The number of antihypertensive drugs prior to surgery was associated with a lower remission rate at the first year and a higher recurrence at 3 years. However, a smaller weight loss during the first year was associated with increased HTN recurrence at 3 years. CONCLUSION HTN relapses in 1 of 5 hypertensives who have achieved remission at the first year of follow-up. Weight loss during the first postoperative year should be encouraged to avoid HTN relapse at 3 years.
    Print ISSN: 0895-7061
    Electronic ISSN: 1879-1905
    Topics: Medicine
    Published by Oxford University Press
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    PAPER CURRENT
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