Case-Based Learning: Predictive Features in Indexing

Interest in psychological experimentation from the Artificial Intelligence community often takes the form of rigorous post-hoc evaluation of completed computer models. Through an example of our own collaborative research, we advocate a different view of how psychology and AI may be mutually relevant, and propose an integrated approach to the study of learning in humans and machines. We begin with the problem of learning appropriate indices for storing and retrieving information from memory. From a planning task perspective, the most useful indices may be those that predict potential problems and access relevant plans in memory, improving the planner's ability to predict and avoid planning failures. This predictive features hypothesis is then supported as a psychological claim, with results showing that such features offer an advantage in terms of the selectivity of reminding because they more distinctively characterize planning situations where differing plans are appropriate.We present a specific case-based model of plan execution, RUNNER, along with its indices for recognizing when to select particular plans—appropriateness conditions—and how these predictive indices serve to enhance learning. We then discuss how this predictive features claim as implemented in the RUNNER model is then tested in a second set of psychological studies. The results show that learning appropriateness conditions results in greater success in recognizing when a past plan is in fact relevant in current processing, and produces more reliable recall of the related information. This form of collaboration has resulted in a unique integration of computational and empirical efforts to create a model of case-based learning.     

Assessment of dermal absorption and penetration of components of a fuel mixture (JP-8)

Occupational and environmental multi-chemical exposures are extremely common. Methods for assessment of the risks from dermal exposures to complex mixtures vary depending on the information available. The composition of a volatile mixture (such as JP-8 jet fuel) can change radically, depending on the phase of the mixture - vapor, liquid or aerosol. Assessing the absorption (into the skin) and penetration (through the skin) of components of the mixture can reduce uncertainty in the risk assessment process. Permeability coefficients of the 12 individual components that could be detected to penetrate the skin could be used to assess the toxicity of each individual component in the JP-8. The penetration of each of these components is related to and can be predicted from molecular weight and octanol water partition coefficients of that component. The composition of the components that penetrate the skin would be different from the composition of JP-8 because the permeability of the components differs by two orders of magnitude. Concentrations of the aliphatic chemicals found in the skin correlated well with carbon number. The JP-8 jet fuel is used as an example of how component data on absorption and penetration can be integrated into an assessment (McDougal et al., Toxicol Sci 2000; 55: 247-255). The component approach shows promise for estimating systemic toxicity of mixtures. Local toxicity (irritation, sensitization, etc.) may be better understood in the future when quantitative information becomes available about the duration and magnitude of chemical exposures required to cause local effects.     

A global gene pool for high-level cephalosporin resistance in commensal Streptococcus species and Streptococcus pneumoniae

Highly penicillin- and cephalosporin-resistant Streptococcus mitis and Streptococcus oralis were isolated in Spain, Hungary, and Berlin. With chromosomal DNA of these strains, resistant transformants of Streptococcus pneumoniae were obtained that expressed low-affinity variants of penicillin-binding proteins (PBPs) 2x, 1a, 2a, and 2b in different combinations, depending on the selective conditions. The transformants had cefotaxime MICs of up to 6 microg/mL, and those with a low-affinity PBP 2b were highly deficient in penicillin-induced lysis. Sequence analysis of the pbp2x genes confirmed the presence of a global gene pool of penicillin resistance determinants shared by commensal and pathogenic streptococci.     

Stress-corrosion cracking in copper refrigerant tubing

A metallurgical failure analysis was conducted to determine the cause of cracking in several sections of copper refrigeration tubing. The tubing in question was part of a new mechanical design, implemented to mitigate fatigue failures of solder joints that had occurred in tubing systems fabricated under the previous design. A comprehensive metallurgical evaluation revealed intergranular fracture of the copper in a region of the tubing that had been significantly cold worked during manufacture. On discovery of a source of moist ammonia in the system, associated with the location of failure, intergranular stress-corrosion cracking (SCC) was identified as the failure mechanism. A modified design, incorporating annealing of the formed copper tube section, was recommended to avoid future failures.     

Microwave-Assisted Synthesis and Characterization of Stearic Acid Sucrose Ester: A Bio-Based Surfactant

Sugar esters of fatty acids are bio-based surfactants that were synthesized by transesterification of table sugar (sucrose) with stearic acid methyl ester (SAME) in high yield and purity using an optimized microwave-assisted method. The maximum surfactant product yield of 88.2% was obtained by combining reactants with potassium methoxide and irradiating the mixture with microwaves to achieve an ideal reaction temperature of 132 °C over 21 min. The synthetic procedure described herein minimized undesirable sugar pyrolysis as evidenced by retention of white color characteristic of a pure bio-based surfactant product. The experiment implemented Box–Behnken design for response surface methodology to refine reaction parameters for optimal product yield. The following parameters were augmented: the irradiation time, the mole ratio of catalyst to sucrose, and temperature.     

Using organizational change procedures to promote the acceptability of prereferral intervention services: The school-based intervention team project.

Prereferral intervention programs represent a consultation-based approach for providing behavioral and/or instructional support to students before considering their eligibility for special class placement. Although research concerning the initial success of these programs has been promising, more information is needed relating program process variables to student outcomes in addition to effective procedures for promoting the adoption of these programs over time. This article describes organizational change procedures that were used to promote the acceptability of a prereferral intervention program at 4 pilot schools. Ss were school-based intervention team members (teachers, teaching assistants, school psychologists, and staff development facilitators) at each school. This article presents evaluation data concerning the program's acceptability to team members and participating teachers, integrity of the consultative process, and effect on numbers of children referred to special education. The implications of these results for school psychologists attempting to promote the acceptability and long-term adoption of prereferral intervention programs are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fluorometric determination of pyruvate and alpha-ketoglutarate in cerebrospinal fluid and plasma of infants and children. A simple test that screen for metabolic disorders

Levels of pyruvate and alpha-ketoglutarate in the cerebrospinal fluid (CSF) of 26 children, aged 4 months to 5 1/2 years, with febrile seizures and of 19 children, aged 4 months to 14 years, with the diagnosis of epilepsy were not different from values seen in 119 "normal" children 8 days to 14 years of age. The CSF samples from 24 adults, 24 to 81 years of age, suspected of having a herniated disk were also examined. In the pediatric age group, the data showed a highly significant downward trend of CSF and plasma alpha-ketoglutarate values with age; pyruvate values did not change. A correlation of the values of the two keto acids in the blood and CSF of 42 other children without apparent neurologic disease was also made. Findings in a child with thiamine deficiency suggest that CSF alpha-ketoglutarate may be a more sensitive indicator of deficiency than plasma alpha-ketoglutarate or pyruvate. Measurements of these keto acids in plasma and CSF may be diagnostically useful in a variety of metabolic disorders. Findings in 155 children from birth (20 minutes) to 17 years of age without neurologic disease are submitted as a standard of reference.