  The memory and rejuvenation aspects of intermittent heat transport are
explored theoretically and by numerical simulation for Ising spin glasses with
short-ranged interactions. The theoretical part develops a picture of
non-equilibrium glassy dynamics recently introduced by the authors. Invoking
the concept of marginal stability, this theory links irreversible
`intermittent' events, or `quakes' to thermal fluctuations of record magnitude.
The pivotal idea is that the largest energy barrier $b(t_w,T)$ surmounted prior
to $t_w$ by thermal fluctuations at temperature $T$ determines the rate $r_q
\propto 1/t_w$ of the intermittent events occurring near $t_w$. The idea leads
to a rate of intermittent events after a negative temperature shift given by
$r_q \propto 1/t_w^{eff}$, where the `effective age' $t_w^{eff} \geq t_w$ has
an algebraic dependence on $t_w$, whose exponent contains the temperatures
before and after the shift. The analytical expression is verified by numerical
simulations. Marginal stability suggests that a positive temperature shift $T
\to T'$ could erase the memory of the barrier $b(t_w,T)$. The simulations show
that the barrier $b(t_w,T') \geq b(t_w,T)$ controls the intermittent dynamics,
whose rate is hence $r_q \propto 1/t_w$.
  Additional `rejuvenation' effects are also identified in the intermittency
data for shifts of both signs.
