We present an experimental approach to study the ultrafast polarization switching dynamics in thin-film ferroelectrics. A semiconductor photoconductive switch with femtosecond laser illumination is used as a ‘‘pulse generator’’ to produce jitter-free, sub-100 ps rise time step-function-like electrical pulses. Quantitative measurements yield a polarization switching time, ts , of ;220 ps when me...

We show that the covariance function of a second-order stationary vector Markov regime switching time series has a vector ARMA(p; q) representation, where upper bounds for p and q are elementary functions of the number of regimes. These bounds apply to vector Markov regime switching processes with both mean-variance and autoregressive switching. This result yields an easily computed method for ...

A hallmark of executive control is the brain's agility to shift between different tasks depending on the behavioral rule currently in play. In this work, we propose a "tweaking hypothesis" for task switching: a weak rule signal provides a small bias that is dramatically amplified by reverberating attractor dynamics in neural circuits for stimulus categorization and action selection, leading to ...

Research using the diffusion model to decompose task-switching effects has contributed to a better understanding of the processes underlying the observed effect in the explicit task cueing paradigm: Previous findings could be reconciled with multiple component models of task switching or with an account on compound-cue retrieval/repetition priming. In the present study, we used two cues for eac...

We discuss the data available for the TSE 300 and S&P 500 total return indexes. We consider a number of models, including the Wilkie model and regime switching models. We discuss calibration by maximum likelihood and by Markov chain Monte Carlo for the regime switching lognormal model. We then show how to use this model to price and hedge simple segregated fund maturity guarantees. keywords: Re...