Bayes' theorem and quantum retrodiction

Abstract

We derive on the basis of Bayes' theorem a simple but general expression for the retrodicted premeasurement state associated with the result of any measurement. The retrodictive density operator is the normalized probability operator measure element associated with the result. We examine applications to quantum optical cryptography and to the optical beam splitter.     

Quantum nature of laser light

All compositions of a mixed-state density operator are equivalent for the prediction of the probabilities of future outcomes of measurements. For retrodiction, however, this is not the case. The retrodictive formalism of quantum mechanics provides a criterion for deciding that some compositions are fictional. Fictional compositions do not contain preparation device operators, that is operators corresponding to states that could have been prepared. We apply this to Mølmer's controversial conjecture that optical coherences in laser light are a fiction and find agreement with his conjecture. We generalize Mølmer's derivation of the interference between two lasers to avoid the use of any fictional states. We also examine another possible method for discriminating between coherent states and photon number states in laser light and find that it does not work, with the equivalence for prediction saved by entanglement.     

A note on the charging of aerosols by overhead line corona

Elevated concentrations of corona ions have been measured in the vicinity of high voltage overhead lines. It is shown that the integrated ion exposure of aerosols in the corona plume is of the order of (x/u)n(x) where n(x) is the ion concentration at distance x downwind from the line and u is the wind speed. Estimated ion exposures are of order 10(11) m(-3) x s, less then 1% of the 10(13) m(-3) x s needed to cause saturation charging of 20 nm aerosols. It is suggested that it is not valid to postulate that AC corona is a health hazard as a consequence of its charging aerosols in the size range 20-125 nm.     

Separation and Recovery of Cobalt from Copper Leach Solutions

JOM - Significant amounts of cobalt, a strategic and critical metal, are present in readily accessible copper recycling leach solutions. However, cost-effective technology is not available to...     

Activating mutations for the met tyrosine kinase receptor in human cancer

Recently, mutations in the Met tyrosine kinase receptor have been identified in both hereditary and sporadic forms of papillary renal carcinoma. We have introduced the corresponding mutations into the met cDNA and examined the effect of each mutation in biochemical and biological assays. We find that the Met mutants exhibit increased levels of tyrosine phosphorylation and enhanced kinase activity toward an exogenous substrate when compared with wild-type Met. Moreover, NIH 3T3 cells expressing mutant Met molecules form foci in vitro and are tumorigenic in nude mice. Enzymatic and biological differences were evident among the various mutants examined, and the somatic mutations were generally more active than those of germ-line origin. A strong correlation between the enzymatic and biological activity of the mutants was observed, indicating that tumorigenesis by Met is quantitatively related to its level of activation. These results demonstrate that the Met mutants originally identified in human papillary renal carcinoma are oncogenic and thus are likely to play a determinant role in this disease, and these results raise the possibility that activating Met mutations also may contribute to other human malignancies.     

Responses of dogs with food allergies to single-ingredient dietary provocation

OBJECTIVE: To characterize specific food ingredients causing allergic reactions in dogs and to assess cross-reactivity between proteins derived from a single animal source or from different plant products. DESIGN: Prospective study. ANIMALS: 25 dogs with histories and cutaneous signs consistent with food-allergic dermatitis. PROCEDURE: Dogs were fed a food-elimination diet until resolution of clinical signs and then challenged with their original diet. A diagnosis of food allergy was made if there was complete return of pruritus within 14 days of challenge exposure. After diagnosis, dogs were fed the food-elimination diet until signs related to dietary challenge abated. The dogs then were fed beef, chicken, chicken eggs, cows' milk, wheat, soy, and corn in single-ingredient provocation trials for 1 week. Any cutaneous reactions to these food ingredients were recorded by their owners. RESULTS: Beef and soy most often caused adverse cutaneous reactions, although all ingredients induced clinical signs in at least 1 dog. Mean number of allergens per dog was 2.4, with 80% reacting to 1 or 2 proteins and 64% reacting to 2 or more of the proteins tested. A significant difference was found between dogs reacting to beef versus cows' milk and between dogs reacting to soy versus wheat; thus, the hypothesis of cross-reactivity to ingredients derived from a single animal source or to different plant products was not supported. Similar differences between chicken meat and eggs were not identified. CLINICAL IMPLICATIONS: Long-term management of dogs with food allergies is facilitated by identification of the most commonly encountered food allergens. Because cross-reactivity cannot be verified, each protein source should be included separately in food-provocation trials.