It is well known that rational bubbles can be sustained in balanced growth path of a deterministic economy when the return to capital r is equal to the growth rate g. When there is a lack of stores of value, bubbles can implement an e¢ cient allocation. This paper considers a world where r ‡uctuates over time due to shocks to the marginal productivity of capital. Then, bubbles further e¢ ciency, though they cannot implement …rst best. While bubbles can only be sustained when r = g in a deterministic economy, r > g "on average" in a stochastic economy.Fiscal policy improves welfare by adding an extra asset. Where only the elderly contribute to shifting resources between investment and consumption in a bubbly economy, …scal policy allows part of that burden to be shifted to the young. Contrary to common wisdom, trade in bubbly assets implements inter generational transfers, while …scal policy implements intragenerational transfers. Hence, while bubbles and …scal policy are perfect substitutes in the deterministic economy, …scal policy dominates bubbles in a stochastic economy. For plausible parameter values, a higher degree of dynamic ine¢ ciency should lead to a higher sovereign debt.1

Previous studies by a number of authors have shown that during a number of BI2-dependent enzyme reactions, e.g., catalysis of amin0-2,l -propano1 to propionaldehyde in the presence of ethanolamine ammonia lyase as reported by Babior et al., a very characteristic e.s.r. spectrum is observed. It consists of a broad line at g -2.3 and a pair of lines in the intensity ratio of approximately 2 : 1, split by 7-14 mT, centred about g = 2. Schepler et al. have given a partial explanation for this and four other similar results, basing their interpretation on isotropic exchange coupling between a radical and the cobalt (11) from BIZ. In this paper we have interpreted the results on the basis of a coupling model which includes both isotropic exchange and dipolar interactions, and which represents a logical extension of previous work of two of the the authors on dissimilar ion coupling. The presence of dipolar coupling brings about an important improvement in the computer simulated lineshapes for the " radical " part of the spectrum, especially foc ethanolamine ammonia lyase. The spectra are also sensitive to the sign of the exchange coupling when second order effects are included in the line positions and, more particularly, the intensities. From comparison between computed and experimental spectra, it is concluded that a lower limit j r the cobalt @)-radical separation of 10 A exists in all cases and that it is in the range 10-12 A for ethanolamine ammonia lyase. Clearly this new information regarding distance must be borne in mind in the development of models for the reactions of such enzyme-substrate-coenzyme systems. E.S.R. O F B 1 2 -~~~~~~~ * SUP 20897 (62 pp.). For details of supplementary Publications see J.C.S. Faraday I and 11, 1976, 73, index issue.

Serum NSE levels were highest in complex partial and subclinical generalized convulsive SE. The extremely high levels of NSE in subclinical SE reflect the severity of the acute neurologic insults and poor outcome common to subclinical SE. High NSE levels in complex partial SE reflects the long duration of SE in this subgroup, and potential for brain injury.

VNS causes activation of several central areas including contralateral thalamus. Localization to the thalamus suggests a possible mechanism to explain the therapeutic benefit, consistent with the role of the thalamus as a generator and modulator of cerebral activity.