Charge centers in CaF2_2: Ab initio calculation of elementary physical properties

Charge centers in ionic crystals provide a channel for elementary interaction between electromagnetic radiation and the lattice. We calculate the electronic ground state energies which are needed to create a charge center -- namely a $F$- and a $H$-center. In well agreement with common understanding the $F$-center results in being accompanied by a small lattice distortion whereas the $H$-center is accompanied by a very large lattice deformation. Opposite to the common understanding the additional positive charge in the charge center results rather to be localized on a F$_4^{3-}$ complex than on a F$_2^-$-complex. From the ground states of the charge centers we derive binding energies, diffusion barriers and agglomeration energies for $M$-center formation. These microscopic quantities are of fundamental interest to understand the dynamic processes which are initiated if the crystals interact with extreme intense deep ultra violet radiation. We further derive the equilibrium concentrations of charge centers in grown crystals.Comment: to appear in Phys. Rev. B in Aug. 2006, 11 Fig

Experimental Evaluation of Interference from MB-OFDM UWB Systems to Narrowband Wireless Digital Transmission Systems

Multi-band orthogonal frequency-division multipleaccess (MB-OFDM) is one of the UWB technologies that realize wireless personal network (WPAN). In this paper, we experimentally investigated the interference from MBOFDM signal to narrowband QPSK digital transmission system. The bit error rate (BER) performance of the narrowband QPSK system under the interference of UWB signal was evaluated, assuming the white Gaussian noise (AWGN) channel. The experimental results show a curve with BER degradation characteristics. The difference of the BER degradation characteristics according to the modulation parameter of the signal is discussed

The International Consortium Investigating Neurocognition in Bipolar Disorder (ICONICâ BD)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148257/1/bdi12748.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148257/2/bdi12748_am.pd