THE IRREVERSIBLE ADSORPTION OF PLUTONIUM HEXAFLUORIDE†

The room temperature adsorption of PuF_6(g) on a solid substrate was compared to the adsorption of UF6(g) on the same surface. Significantly more PuF_6(g) was adsorbed at pressures in the range of 1.2 to 0.2torr, accompanied by the evolution of molecular fluorine. The adsorbed UF₆ was easily desorbed by reducing the pressure. Most of the adsorbed PuF₆ remained on the surface when subjected to the same treatment.     

The prediction of transport parameters in filamentous fermentation broths based on results obtained in pseudoplastic polymer solutions

Transport phenomena studies on single phase “model” fluids are of limited value in biochemical engineering if they cannot be translated to the heterogeneous systems encountered in real fermentation processes. In this paper we discuss the utility of polymer solutions as models of filamentous fermentation broths for evaluation of: pipeline friction factors and impeller power numbers (turbine and helical ribbon). To a first approximation, polymer solutions can serve as suitable models for the prediction of laminar flow pressure drop in pipelines and turbulent power consumption in stirred tanks. However, results obtained on polymer solutions do not directly apply to filamentous fermentation broths for predictions of laminar flow impeller power consumption and the transition point for turbulent flow in stirred tanks. These discrepancies are believed to result from the existence of a time dependent yield stress in filamentous fermentation broths.     

Molecular beam studies of fullerenes

A number of molecular beam experiments with the fullerenes are described. Such experiments allow a detailed probing of the interactions between fullerenes and other species and among the fullerenes themselves. Emphasis is placed on work involving photophysics and collisional interactions of the fullerenes.     

The mechanism of CO oxidation over Cu(110): Effect of CO gas energy

The effect of the temperature of gas phase CO upon the kinetics of the oxygen titration reaction: CO_g +O_a CO_2,g, has been studied. It is found that the reaction's rate is independant of CO gas temperature between 300 and 623 K. The activation energy (6.5 kcal/mole), dependence upon CO pressure (first-order), and independence upon oxygen coverage for 0.1 _o 0.4 are all independant of the CO gas phase temperature. This result rules out any Eley-Rideal type mechanism whereby CO reacts directly from the gas phase with an oxygen adatom without first being accommodated to the surface temperature in an absorbed state. The result is instead interpretable in terms of a Langmuir-Hinshelwood mechanism.Camille and Henry Dreyfus Foundation Teacher-Scholar Fellowship.     

Map‐aided localization in sparse global positioning system environments using vision and particle filtering

A map‐aided localization approach using vision, inertial sensors when available, and a particle filter is proposed and empirically evaluated. The approach, termed PosteriorPose, uses a Bayesian particle filter to augment global positioning system (GPS) and inertial navigation solutions with vision‐based measurements of nearby lanes and stop lines referenced against a known map of environmental features. These map‐relative measurements are shown to improve the quality of the navigation solution when GPS is available, and they are shown to keep the navigation solution converged in extended GPS blackouts. Measurements are incorporated with careful hypothesis testing and error modeling to account for non‐Gaussian and multimodal errors committed by GPS and vision‐based detection algorithms. Using a set of data collected with Cornell's autonomous car, including a measure of truth via a high‐precision differential corrections service, an experimental investigation of important design elements of the PosteriorPose estimator is conducted. The algorithm is shown to statistically outperform a tightly coupled GPS/inertial navigation solution both in full GPS coverage and in extended GPS blackouts. Statistical performance is also studied as a function of road type, filter likelihood models, bias models, and filter integrity tests. © 2011 Wiley Periodicals, Inc.     

The "hidden observer" phenomenon in hypnosis: Some additional findings.

23 highly hypnotizable undergraduates (Harvard Group Scale of Hypnotic Susceptibility) underwent 2 specially constructed 7-item hypnotic inductions. Over the 14 items, the main finding was of a relationship between E. R. Hilgard's (1973, 1977, 1979) "hidden observer" effect and 2 aspects of hypnotic age regression. Ss reporting a hidden observer experienced duality during regression to age 5, in which they were aware of being both adult and child. When asked to write a complex sentence, most did so, usually without spelling errors. The Ss not reporting this effect experienced quasi-lateral age regression in which they had the exclusive feeling of being 5 yrs old, with no sense of an adult identity. Most of these Ss were unable to write the same complex sentence when requested to during age regression. The study replicated Hilgard's finding of the hidden observer phenomenon in terms of its incidence and obtained similar verbal reports from Ss experiencing it. At the same time, the results suggest that a neodissociation account of hypnosis may need some modifications to accommodate these additional findings. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cashing in on Caching: An Architecture for Time-Bounded Knowledge-Based Problem Solving

Knowledge-based computing, in general, suffers from an inherent open-endedness that precludes its application in time-bounded domains where an answer must be computed within a stipulated time limit. We examine a two-way improvement of the shortcomings: a knowledge representation scheme that provides easy access to relevant knowledge and thereby reduces search time, and a reasoning scheme that is algorithmic in nature and thus makes computational requirements meaningfully estimable.In this work, we offer a cache-based architecture that is capable of both storing knowledge in different formats (e.g. rules, cases), and invoking an appropriate reasoning scheme to fit the available computing time. The cache helps in retrieving the most relevant pieces of knowledge (not only exact matches) required for solving a given problem. This cache relies on a reasoning tactic, knowledge interpolation, that can generate a solution from two near-matches in an algorithmic way, to generate time-bounded solutions. We illustrate the design of such a cache for solving resource allocation problems in the domain of shortwave radio transmission and evaluate its performance in observing imposed temporal bounds.