Narrow Results

Size and position of rapidity window dependence of charge fluctuations and correlations are studied by PYTHIA and RQMD models for hadron–hadron and nucleus–nucleus collisions respectively. The results show that all the measures for charge fluctuations and correlations depend on the size of central rapidity windows and most of them depend on the position of the rapidity windows, which is not expected. Only charge balance function in hadron–hadron collisions is independent of the position of rapidity window, i.e. boost-invariant, in consistent with corresponding experimental data, while charge fluctuations measured by D(Q) is not boost-invariant in contrast to the experimental data. The measures for three kind of charge correlations (R₊₊, R_--, R_+-) show a good account for the behavior of charge correlations and global charge conservation in longitudinal phase space in both PYTHIA and RQMD.

Keeping power consumption low in implantable neuro-stimulators such as Cochlear Implants or Vision Prostheses is one of the major design challenges in their circuit design. Usually electrode impedance and stimulation currents required to elicit physiological responses mandates the use of large stimulation voltages, again dictating the use of high-voltage integrated circuit technologies. Power consumption in the stimulating circuits and associated supply generation circuits are the major contributors to overall system power dissipation. In this paper we present circuit design techniques that address power consumption in both stimulating circuits and power supply circuits. First, our power supply design approach is to recycle currents between the two low-voltage power supply needed for the stimulating circuits, whereby power consumption in these circuits can be close to halved. Second, our stimulating circuits design approach is to use very small quiescent currents, fast turn-on time and pre-stimulating dynamic calibration which allow the delivery of charge balanced bi-phasic stimulation pulses with very good power efficiency. A variation of this include passive charge recovery for further power reduction. In combination, significant implant power consumption reduction is achieved.