Time Coefficient Estimation for Hourly Origin-Destination Demand from Observed Link Flow Based on Semidynamic Traffic Assignment

Day-long origin-destination (OD) demand estimation for transportation forecasting is advantageous in terms of accuracy and reliability because it is not affected by hourly variations in the OD distribution. In this paper, we propose a method to estimate the time coefficient of day-long OD demand to estimate hourly OD demand and to predict hourly traffic for urban transportation planning of a large-scale road network that lacks discrete-time rich traffic data. The model proposed estimates the time coefficients from observed link flows given a proven day-long OD demand based on a bilevel formulation of the generalized least square and semidynamic traffic assignment (OD-modification approach). The OD-modification approach is formulated as a static user-equilibrium assignment with elastic demand, based on the residual demand at the end of each period. Our model does not require setting many parameters regarding the OD demand matrices and the discrete-time dynamic traffic assignments. Applying the model to large-scale road network demonstrates that it efficiently improves estimation accuracy because the 24-hour time coefficients of survey data are slightly biased and may be modified properly. In addition, the methods that partially relax the assumption of OD-modification approach and transform the estimated demand into demand based on departure time are examined.

Blockade of Cyclic AMP-Dependent Protein Kinase Does Not Prevent the Reverse Ocular Dominance Shift in Kitten Visual Cortex

Monocular deprivation (MD) during the critical period for the development of visual cortex causes a loss of binocular response of neurons and a shift to the open eye, a normal ocular dominance (OD) shift. However, when MD is combined with chronic inactivation of the visual cortex by muscimol, the OD distribution of the neurons shifts to the deprived eye (reverse OD shift). We have previously shown that the normal OD shift is abolished by chronic infusion of the protein kinase A (PKA) inhibitor, 8-chloroadenosine-3′, 5′-cyclic monophosphorothioate, Rpisomer (Rp-8-Cl-cAMPS), into kitten visual cortex. In this study, we investigated the effect of this inhibitor on the reverse OD shift. Combination of MD and muscimol infusion into the visual cortex of 6-wk-old kittens caused a reverse OD shift that was comparable to that seen in previous studies. However, a reverse OD shift was also seen with concurrent infusion of the PKA inhibitor with muscimol. The strongest OD shift was observed in layer IV regardless of the presence or absence of the PKA inhibitor. This suggests that the dissociation of pre- and postsynaptic activities, which occurs mainly at thalamocortical synapses, induces the reverse OD shift and that inhibition of PKA does not prevent it. Presumably, an inhibition of PKA has no effect in silent cortex. We conclude that 1) an activation of PKA is not required for the induction of the reverse OD shift, and 2) the intracellular signaling mechanism underlying MD-induced OD plasticity differs between normal and reverse OD shifts.