Browsing Research Output by Title

Now showing items 2422-2441 of 13384

    • Cosmic ray modulation with a Fisk-type heliospheric magnetic field and a latitude-dependent solar wind speed 

      Hitge, M.; Burger, R.A. (Elsevier, 2009)
      The effect of a latitude-dependent solar wind speed on a Fisk heliospheric magnetic field [Fisk, L. A. Motion of the footpoints of heliospheric magnetic field lines at the Sun: implications for recurrent energetic particle ...

    • Cosmic rays in astrospheres 

      Scherer, K.; Van der Schyff, A.; Ferreira, S.E.S.; Strauss, R.D.; Bomans, D.J. (EDP Sciences, 2015)
      Context: Cosmic rays passing through large astrospheres can be efficiently cooled inside these “cavities” in the interstellar medium. Moreover, the energy spectra of these energetic particles are already modulated in front ...

    • Cosmic rays in the dynamic heliosheath 

      Ferreira, S.E.S.; Potgieter, M.S.; Scherer, K. (Elsevier, 2008)
      Cosmic ray modulation in the outer heliosphere is discussed from a modeling perspective. Emphasis is on the transport and acceleration of these particles at and beyond the solar wind termination shock in the inner heliosheath ...

    • Cosmic rays in the dynamic heliosphere 

      Potgieter, Marius S. (Japan Society of Plasma Science and Nuclear Fusion Research, 2009)
      he relation between the dynamics of the heliosphere, its shape and geometry, so lar activity and cosmic ray variations is addressed. The global features of the helio sphere influence what happens inside its boundaries ...

    • Cosmic rays in the heliosphere: observations 

      Moraal, Harm (Elsevier, 2014)
      This contribution to the 100th commemoration of the discovery of cosmic rays (6–8 August, 2012 in Bad Saarow, Germany) is about observations of those cosmic rays that are sensitive to the structure and the dynamics of the ...

    • Cosmic rays in the inner heliosphere: insights from observations, theory and models 

      Potgieter, M.S. (Springer, 2011)
      The global modulation of galactic cosmic rays in the inner heliosphere is determined by four major mechanisms: convection, diffusion, particle drifts (gradient, curvature and current sheet drifts), and adiabatic energy ...

    • Cosmic-ray acceleration and escape from post-adiabatic supernova remnants 

      Brose, R.; Sushch, I.; Pohl, M.; Petruk, O.; Kuzyo, T. (EDP Sciences, 2020)
      Context. Supernova remnants are known to accelerate cosmic rays on account of their nonthermal emission of radio waves, X-rays, and gamma rays. Although there are many models for the acceleration of cosmic rays in supernova ...

    • The cosmic-ray ground-level enhancement of 1989 September 29 

      Moraal, H.; Cabellero-Lopez, R.A. (IOP Publishing, 2014)
      The ground-level enhancement (GLE) of 1989 September 29 is one of the largest of 71 solar energetic particle events observed by neutron monitors on Earth. It was smaller than the record-breaking GLE 5 of 1956 February 23, ...

    • Cosmic-ray modulation equations 

      Moraal, Harm (Springer, 2011)
      The temporal variation of the cosmic-ray intensity in the heliosphere is called cosmic-ray modulation. The main periodicity is the response to the 11-year solar activity cycle. Other variations include a 27-day solar ...

    • Cosmic-ray modulation: an ab initio approach 

      Engelbrecht, N.E.; Burger, R.A. (Springer Verlag, 2014)
      A better understanding of cosmic-ray modulation in the heliosphere can only be gained through a proper understanding of the effects of turbulence on the diffusion and drift of cosmic rays. We present an ab initio model ...

    • A cosmic-ray positron anisotropy due to two middle-aged, nearby pulsars? 

      Büsching, I.; De Jager, O.C.; Potgieter, M.S.; Venter, C. (IOP Publishing, 2008)
      Geminga and B0656+14 are the closest pulsars with characteristic ages in the range of 100 kyr to 1 Myr. They both have spin-down powers of the order 3 × 1034 ergs s–1 at present. The winds of these pulsars had most probably ...

    • Cosmic-ray positrons from millisecond pulsars 

      Venter, C.; Kopp, A.; Büsching, I.; Harding, A.K.; Gonthier, P.L. (IOP Publishing, 2015)
      Observations by the Fermi Large Area Telescope of γ-ray millisecond pulsar (MSP) light curves imply copious pair production in their magnetospheres, and not exclusively in those of younger pulsars. Such pair cascades may ...

    • Cosmic-ray transport in heliospheric magnetic structures. II. Modeling particle transport through corotating interaction regions 

      Kopp, Andreas; Raath, Jan Louis; Potgieter, Marius S.; Wiengarten, Tobias; Fichtner, Horst (IOP, 2017)
      The transport of cosmic rays (CRs) in the heliosphere is determined by the properties of the solar wind plasma. The heliospheric plasma environment has been probed by spacecraft for decades and provides a unique opportunity ...

    • Cosmic-ray yield and response functions in the atmosphere 

      Caballero-Lopez, R.A.; Moraal, H. (American Geophysical Union, 2012)
      Since the middle 1950s, neutron monitors have provided a continuous record of the intensity of secondary atmospheric particles produced by the primary cosmic radiation above the atmosphere. The number of counts due to ...

    • Cosmological Chaplygin gas as modified gravity 

      Elmardi, Maye; Abebe, Amare (IOP Publishing, 2017)
      In the scramble for the understanding of the nature of dark matter and dark energy, it has recently been suggested that the change of behavior of the missing energy density might be regulated by the change in the equation ...

    • The cosmological perturbed lightcone gauge 

      Elmardi, Maye (MDPI, 2018)
      The lightcone gauge is a set of what are called the observational coordinates adapted to our past lightcone. We develop this gauge by producing a perturbed spacetime metric that describes the geometry of our past lightcone ...

    • Cosmologies of the ancient Mediterranean world 

      Fitzgerald, John T. (OASIS, 2013)
      Cosmology is concerned with the order of the universe and seeks to provide an account, not only of that order, but also of the mind or reason behind it. In antiquity, the cosmos was usually understood religiously, such ...

    • Cosmology in the book of Revelation 

      Jordaan, Gert J.C. (OASIS, 2013)
      The cosmology of the book of Revelation mainly involves God’s restored reign over the created universe (κόσμος). Throughout the book, the κόσμος is depicted according to its constituent parts, namely heaven, sea and ...

    • Cosmos, reality and God in the letters of John 

      Van der Watt, Jan (OASIS, 2013)
      The major question addressed in this article is how reality, especially cosmic reality, is perceived in 1 John; in other words: What are the elements of John’s cosmological vision as it becomes apparent in his letters? ...

    • The cost of banking services and the technical efficiency of a South African bank 

      Van Heerden, C.; Van der Westhuizen, G. (2008)
      Does the performance of one of the four largest banks in South Africa justify the customers’ complaints about the higher bank fees? Data Envelopment Analysis (DEA) was used to estimate the technical efficiency and returns ...