A pair (X, Y) of Markov processes is called a Markov coupling if X and Y have the same transition probabilities and (X, Y) is a Markov process. We say that a coupling is " shy " if there exists a (random) ε > 0 such that dist(X t , Y t) > ε for all t ≥ 0. We investigate whether shy couplings exist for several classes of Markov processes.

Plasma catecholamines and circulation parameters were studied in a patient with a Shy-Drager syndrome. Basal values of free noradrenaline and dopamine were within the normal range, whereas the adrenaline level was decreased. The response of plasma catecholamines to different kinds of physical activity was pathological. The inability to maintain elevated catecholamine levels during prolonged act...

In the current brief report, we examined threat perception in a group of young children who may be at-risk for anxiety due to extreme temperamental shyness. Results demonstrate specific differences in the processing of social threats: 4- to 7-year-olds in the high-shy group demonstrated a greater bias for social threats (angry faces) than did a comparison group of low-shy children. This pattern...

Seven-year-olds completed a Posner cued attention task, under both neutral and affectively charged conditions. Compared to the traditional (affect-neutral) Posner task, performance in the affective Posner task was marked by dramatic decreases in reaction times (RTs), an increase in errors, an increased validity effect (difference in RTs to the cued vs. uncued trials), and increased electrocorti...

Christensen has defined a generalization of the property of being of Haar measure zero to subsets of (abelian) Polish groups which need not be locally compact; a recent paper of Hunt, Sauer, and Yorke defines the same property for Borel subsets of linear spaces, and gives a number of examples and applications. The latter authors use the term “shyness” for this property, and “prevalence” for the...