Localization of Negative Energy and the Bekenstein Bound

A simple argument shows that negative energy cannot be isolated far away from positive energy in a conformal field theory and strongly constrains its possible dispersal. This is also required by consistency with the Bekenstein bound written in terms of the positivity of relative entropy. We prove a new form of the Bekenstein bound based on the monotonicity of the relative entropy, involving a "free" entropy enclosed in a region which is highly insensitive to space-time entanglement, and show that it further improves the negative energy localization bound.Comment: 5 pages, 1 figur

Multiplicative versus additive noise in multi-state neural networks

The effects of a variable amount of random dilution of the synaptic couplings in Q-Ising multi-state neural networks with Hebbian learning are examined. A fraction of the couplings is explicitly allowed to be anti-Hebbian. Random dilution represents the dying or pruning of synapses and, hence, a static disruption of the learning process which can be considered as a form of multiplicative noise in the learning rule. Both parallel and sequential updating of the neurons can be treated. Symmetric dilution in the statics of the network is studied using the mean-field theory approach of statistical mechanics. General dilution, including asymmetric pruning of the couplings, is examined using the generating functional (path integral) approach of disordered systems. It is shown that random dilution acts as additive gaussian noise in the Hebbian learning rule with a mean zero and a variance depending on the connectivity of the network and on the symmetry. Furthermore, a scaling factor appears that essentially measures the average amount of anti-Hebbian couplings.Comment: 15 pages, 5 figures, to appear in the proceedings of the Conference on Noise in Complex Systems and Stochastic Dynamics II (SPIE International

A NEW OUTCOME MEASURE FOR COST-UTILITY ANALYSES OF SCREENING PROGRAMS

In this paper we provide a new outcome measure for the cost-utility analyses of alternative screening programs of a particular disease. We show that for non-invasive screening programs satisfying plausible assumptions, QALYs can be replaced by a simpler outcome: the sensitivity of the program. In other words, the cost-utility analysis can be made without computing the utility each program offers. Consequently, results would be immune to two of the most controversial issues in the cost-utility analysis approach: the elicitation method to obtain quality weights of health profiles, and the discount rate for future health benefits. The assumptions are particularly suitable in the case of selecting between the universal and the selective implementation of a non-invasive screening program. Therefore, we apply our result to provide an additional viewpoint in the current debate about the implementation of a universal or selective newborn screening program to detect congenital hearing impairment.Cost-utility analysis, cost-sensitivity ratios, screening programs,