Detecting and correcting errors in ruled-based expert systems : an integration of empirical and explanation-based learning

In this paper, we argue that techniques proposed for combining empirical and explanation-based learning methods can also be used to detect errors in rule-based expert systems, to isolate the blame for these errors to a small number of rules and suggest revisions to the rules to eliminate these errors. We demonstrate that FOCL, an extension to Quinlan's FOIL program, can learn in spite of an incorrect domain theory (e.g., a knowledge base of an expert system that contains some erroneous rules). A prototype knowledge acquisition tool, KR-FOCL, has been constructed that can utilize a trace of FOCL to suggest revisions to a rule base

Concept for a large multipurpose launch vehicle

Multipurpose single stage launch vehicle configuration feasibility stud

An information-based approach to integrating empirical and explanation-based learning

We describe a new approach to integrating explanation-based and empirical learning methods for learning relational concepts. The approach uses an information-based heuristic to evaluate components of a hypothesis that are proposed either by explanation-based or empirical methods. Providing domain knowledge to the integrated system can decrease the amount of search required during learning and increase the accuracy of learned concepts, even when the domain knowledge is incorrect and incomplete and there is noise in the training data

Aerodynamic studies of non-planar and near-circular motions Summary report

Polar equation of yawing motion for analysis of nonplanar and near-circular motions of missile

A Geomorphological Assessment of Armored Deposits Along the Southern Flanks of Grand Mesa, CO, USA

A series of deposits, located along the southern flanks of Grand Mesa, Colorado, and extending to the south, are problematic, and the processes related to emplacement are not understood. The overall area is dominated by two landform systems, Grand Mesa, which supported a Pleistocene ice cap, and the North Fork Gunnison River drainage. Thus, one has to ask: Are these deposits the result of the melting of the ice cap or are they fluvial terraces associated with the evolution of the ancestral Gunnison River? The goal of this research was to map the areal extent of the deposits and to interpret the formation and climatic significance in understanding the evolution of the Pleistocene landscape in the region. An extensive exposure, parallel to State Highway 65 near Cory Grade, was used for detailed description and sampling. Three additional exposures, ~10 to 20 km (~6 to 12 mi) were used to extend the areal extent of sampling. The study area was mapped using aerial photography and traditional field mapping aided by GPS. From the field work, a detailed stratigraphic column, including lithology and erodability, was constructed. Vertical exposures of the deposits were described, mapped, and recorded in the field and using detailed photo mosaics. Samples were collected from each stratum of the deposits for grain-size, shape, and sorting analyses. Five distinct depositional facies were identified. Sieve analysis on collected samples shows that four distinct grain-sizes occur in the outcrops; coarse sand, very-coarse sand, granule, and pebble and boulder. Mean grain-sizes range from 0.0722 to 0.9617, -0.0948 to -0.9456, -1.0566 to -1.9053, and -2.0050 to -3.4643, respectively. Glacio-fluvial depositional environments were identified and supported with observations of sedimentary structures and clast composition. Two major environments of deposition are recorded in the deposits; fluvial deposits from glacial outburst floods, and debris flow deposits. Imbrication of clasts in the strata suggests the flow came from the direction of Grand Mesa to the north. Facies and subsequent sequences were constructed to portray evidence that supports the glacio-fluvial mode of deposition

A Mechanochemical Switch to Control Radical Intermediates

B12-dependent enzymes employ radical species with exceptional prowess to catalyze some of the most chemically challenging, thermodynamically unfavorable reactions. However, dealing with highly reactive intermediates is an extremely demanding task, requiring sophisticated control strategies to prevent unwanted side reactions. Using hybrid quantum mechanical/molecular mechanical simulations, we follow the full catalytic cycle of an AdoB12-dependent enzyme and present the details of a mechanism that utilizes a highly effective mechanochemical switch. When the switch is “off”, the 5′-deoxyadenosyl radical moiety is stabilized by releasing the internal strain of an enzyme-imposed conformation. Turning the switch “on,” the enzyme environment becomes the driving force to impose a distinct conformation of the 5′-deoxyadenosyl radical to avoid deleterious radical transfer. This mechanochemical switch illustrates the elaborate way in which enzymes attain selectivity of extremely chemically challenging reactions

A large-scale proteogenomics study of apicomplexan pathogens-Toxoplasma gondii and Neospora caninum

Proteomics data can supplement genome annotation efforts, for example being used to confirm gene models or correct gene annotation errors. Here, we present a large‐scale proteogenomics study of two important apicomplexan pathogens: Toxoplasma gondii and Neospora caninum. We queried proteomics data against a panel of official and alternate gene models generated directly from RNASeq data, using several newly generated and some previously published MS datasets for this meta‐analysis. We identified a total of 201 996 and 39 953 peptide‐spectrum matches for T. gondii and N. caninum, respectively, at a 1% peptide FDR threshold. This equated to the identification of 30 494 distinct peptide sequences and 2921 proteins (matches to official gene models) for T. gondii, and 8911 peptides/1273 proteins for N. caninum following stringent protein‐level thresholding. We have also identified 289 and 140 loci for T. gondii and N. caninum, respectively, which mapped to RNA‐Seq‐derived gene models used in our analysis and apparently absent from the official annotation (release 10 from EuPathDB) of these species. We present several examples in our study where the RNA‐Seq evidence can help in correction of the current gene model and can help in discovery of potential new genes