question: Acta Crystallographica and Journal of Synchrotron Radiation are defined as what?
answer: peer-reviewed scientific journal
context: Title: Acta Crystallographica
  Passage: Acta Crystallographica is a series of peer-reviewed scientific journals, with articles centred on crystallography, published by the International Union of Crystallography (IUCr).  Originally established in 1948 as a single journal called "Acta Crystallographica", there are now six independent "Acta Crystallographica" titles: "", "", "", "", "" and "".  "Acta Crystallographica" has been noted for the high quality of the papers that it produces, as well as the large impact that its papers have had on the field of crystallography.  The current six journals form part of the journal portfolio of the IUCr, which is completed by the "Journal of Applied Crystallography", the "Journal of Synchrotron Radiation", the open-access "IUCrJ" and the open-access data publication "IUCr Data".
  Title: Journal of Synchrotron Radiation
  Passage: The Journal of Synchrotron Radiation is a peer-reviewed scientific journal published by Wiley-Blackwell on behalf of the International Union of Crystallography.  It was established in 1994 and covers research on synchrotron radiation and its applications.  The editor-in-chief is S. Samar Hasnain (University of Liverpool).
  Title: Cyclotron turnover
  Passage: Cyclotron turnover is one of two phenomena due to which the power spectrum of synchrotron radiation decreases at very low frequencies.  The other is synchrotron self-absorption.  While the synchrotron self-absorption is determined from detailed balance, cyclotron turnover occurs when the assumptions of synchrotron radiation are violated.  We recall that when a charged particle moves in a magnetic field its orbit is a helix, and its velocities can be divided into two independent components: uniform velocity parallel to the axis of the helix, and rotation about the axis.  Synchrotron radiation requires that both velocities be ultra-relativistic, but if the velocity parallel to the axis is relativistic and the rotation is not, then the spectrum would simply be that of a Doppler shifted cyclotron radiation, and this behavior is called cyclotron turnover.  In real systems there would be a competition between these two phenomena, so the only one that sets in at higher frequencies will be observed.  An interesting feature about the cyclotron turnover is that it allows emission at frequencies lower that the cyclotron frequency, if the particle is moving away from the observer.
  Title: Hiroshima Synchrotron Radiation Center
  Passage: The Hiroshima Synchrotron Radiation Center, also known as Hiroshima Synchrotron Orbital Radiation (HiSOR), at Hiroshima University is a national user research facility in Japan.  It was founded in 1996 by the University Science Council at Hiroshima University initially as a combined educational and research facility before opening to users in Japan and across the world in 2002.  It is the only synchrotron radiation experimental facility located at a national university in Japan.
citations: Acta Crystallographica Journal of Synchrotron Radiation