X-ray Takagi-Taupin dynamical theory generalized to n-beam diffraction cases.
A new X-ray dynamical diffraction theory that can deal with n-beam cases comprehensively (n in [3, 4, 6, 8, 12]) has been derived based on the Takagi-Taupin dynamical theory. The new theory takes into account correctly the effects of arbitrarily polarized incident X-rays and the polarization states of X-ray wavefields in a crystal. Furthermore, an arbitrary lattice displacement in the crystal can be dealt with. The new theory has a high symmetry and therefore can be written with one equation supposing that suffixes are taken in 2n ways, where the suffixes indicate ordinal numbers of waves and polarization states. This simplicity of the theory enables a computer program to solve the equations to be coded easily. A method to solve the theory numerically is also described. 'Six-beam X-ray section topographs' computer simulated based on the new theory are also presented.
Polarization-dependent six-beam X-ray pinhole topographs.
X-ray six-beam pinhole topograph images were obtained for a silicon crystal with incident synchrotron X-rays. The polarization state of X-rays incident on the sample crystal was controlled by using a four-quadrant phase-retarder system [Okitsu et al. (2002). Acta Cryst. A58, 146-154] that can be rotated around the transmitted beam axis to generate arbitrarily polarized X-rays. Quantitative agreement was found between the experimental and computer-simulated topograph images based on the n-beam Takagi-Taupin dynamical theory under the assumption that the polarization state of the incident X-rays was identical with the experiment. This result confirmed the validity of the computer algorithm to solve the n-beam dynamical theory and the proper operation of the rotating four-quadrant phase-retarder system simultaneously.
Warm Hands in Cold Age – On the Need of a New World Order of Care
The world is aging as fertility and mortality are both decreasing. This article focuses on practical care work for the elderly. Such work is done primarily by women even though a larger portion than previously is paid rather than unpaid. All over the world, most elderly care work is organized within the family, most often unpaid. Men receive more care from partners than women, while women receive more care from female relatives. When care work is paid, the payment is generally low. A comparison between Germany, Spain, and Sweden demonstrates similar gender patterns, even though the role of the state in supporting care differs considerably as do care workers' conditions. The sustainability of today's distribution and organization of care work is questioned as the need for care increases, and the possibility of more equal sharing of care work between women and men is explored.