Predicate invention and utilization

Abstract

Inductive logic programming (ILP) involves the synthesis of logic programs from examples. In terms of scientific theory formation ILP systems define observational predicates in terms of a set of theoretical predicates. However, certain basic theorems indicate that with an inadequate theoretical vocabulary this is not always possible. Predicate invention is the augmentation of a given theoretical vocabulary to allow finite axiomatization of the observational predicates. New theoretical predicates need to be chosen from a well-defined universe of such predicates. In this paper a partial order of utilization is described over such a universe. This ordering is a special case of a logical translation. The notion of utilization allows the definition of an equivalence relationship over new predicates. In a manner analogous to Plotkin, clause refinement is defined relative to given background knowledge and a universe of new predicates. It is shown that relative least clause refinement is defined and unique whenever there exists a relative least general generalization of a set of clauses. Results of a preliminary implementation of this approach are given.     

New management policies to improve the effectiveness of multi-station service organizations

Clark et al ( 1992)reported on the use of a computer simulation model to show that significant reduction in customer ‘ waiting time’ could be achieved by new management policies for multi-station service organizations. They modelled a multi-phase queuing structure and showed reductions in the system variable ‘ time in system’ when servers were pooled at the first reception desk, rather than having single servers at multiple desks to provide service. Their model also demonstrated a greater savings in system transit time when the servers moved with the customers through subsequent tasks (multi-phase systems) This paper uses classical queuing theory to evaluate these results. We conclude that Clark et al' s findings can be supported through use of the classical waiting line formulas.     

Shoot growth on de-fruited grapevines: a physiological indicator for irrigation scheduling

A simple and inexpensive but biologically meaningful way of gauging grapevine water status that can guide irrigation scheduling is described. The growth rate of shoots on grapevines from which all fruit has been removed (de-fruited shoot growth) is presented as a sensitive indicator of vine and soil water status and we propose a procedure for irrigation scheduling based on monitoring de-fruited shoot growth and soil moisture. These guidelines were derived from corresponding measurements of de-fruited shoot growth and soil moisture potential that were undertaken at frequent intervals (generally 1 to 2 days). De-fruited shoot growth rate between 48 and 71 days after anthesis was linearly correlated with the mean moisture potential of the soil at depths of 60 cm and 90 cm in the centre of the drip-irrigated zone (r = 0.94). De-fruited shoot growth effectively ceased when soil moisture potential at these points had decreased to -70 kPa, although much of the root zone would have been even drier. De-fruited shoot growth thus shows an integrated and dynamic response to vine-available soil water that could aid irrigation scheduling.     

Frozen Storage Performance of Cooked Cultivated Mussels (Mytilus edulis L.)—Influence of Ascorbic Acid and Chelating Agents

The usefulness of ascorbic acid and chelating agents in retarding sensory deterioration and progression of oxidative rancidity in frozencooked mussels was investigated. Ascorbic acid with and without chelating agents proved effective in arresting progression of oxidative rancidity, in samples held at – 12°C for 20 wk. However, these agents proved ineffective in preventing sensory deterioration of mussel meats under the same conditions. Mussels held at – 30°C showed an improved sensory stability throughout the study and demonstrated less progression of lipid oxidation compared with mussels held at – 12°C. Sensory deterioration at – 12°C storage is associated in part, with lipid oxidative changes. The ineffectiveness of antioxidant agents in preventing sensory deteriorative changes may indicate the presence of other, as yet undetermined, degradative pathways.     

CULTURAL HEGEMONY AS AN IMPEDIMENT TO URBAN PROTEST MOVEMENTS: Grassroots Activism and Downtown Development in Washington,DC

ABSTRACT: This article explores the role of political culture in either reinforcing or undermining entrenched patterns of limited policy making in American cities. In a departure from recent research on the impetus for cultural/political change, this study shifts the focal point away from sweeping societal forces and toward the deliberate efforts of individuals engaging in collective action. Building on Gramscian theory, this ethnographic analysis of the politics of downtown development in Washington, DC, demonstrates how even activists passionately committed to reforming public policy may unwittingly reaffirm a local political cultural that legitimizes existing power relations. The implication is that alternative forms of grasroots activism are capable of engendering cultural/political change.     

Utilization of Glucose Oxidase for Extending the Shelf-Life of Fish

The preservative benefits of the enzymic glucose oxidase/catalase system were measured in refrigerated, fresh, whole winter flounder (Pseudopleuronectes americanus Waldbaum) and winter flounder fillets. The enzyme system was applied as a dip, as an ice and immobilized in algin blankets. Advantages were an extended period of sensory acceptance and delayed onset of putrefactive odors, 21 days vs 15 days for controls. The pattern of endogenous hypoxanthine accumulation and decline was unaffected, but parameters thought to measure proteolytic activity were modified: creatinine turnover was slowed and ammonia generation was retarded.     

Cognitive Set and Food Acceptance

A consumer panel was randomly divided into two groups. Each group was asked to rate the acceptance of an almond nut dairy bar on five consecutive days and to complete a 30-item questionnaire about their current physical state. For the positive group, all the statements were positive (e.g., “I feel great”), while for the negative group all the statements were negative (e.g., “I feel tired”). Acceptance ratings of the dairy bars were significantly higher for the positive group than for the negative group but questionnaire responses did not change over the five days of the experiment.     

On making expert systems more like experts

Abstract: Expert systems still lack the skill of an expert when it comes to providing explanations of the results of expert reasoning. This is because while such systems may implement knowledge which is sufficient to mimic the performance of an expert, they do not necessarily model the expertise upon which that performance is based. Such a model must include knowledge of that domain's terminology, knowledge of domain facts, and knowledge of problem-solving methods. The Explainable Expert Systems project has been exploring a new paradigm for expert system development that is intended to capture such missing knowledge and make it available for explanation. This paper will discuss the principles behind this paradigm and consider two systems that employ it.     

Isolation and Identification of Volatile Compounds from Roasted Peanuts

Volatile flavor compounds were isolated from 70 kg of freshly roasted Florida Runner peanuts by a specially designed apparatus. The isolated volatile flavor compounds were subjected to extensive gas chromatographic fractionation and the pure fractions obtained were identified by infrared and mass spectrometry. A total of 131 compounds was identified. The following compounds are reported for the first time as flavor components of roasted peanuts: five lactones, incluing γ-crotolactone, 3-methyl-γ-crotolactone and 5-hydroxy-4-nonenoic acid, lactone; four pyrazines, three pyrroles; three pyridines, 13 sulfides, including three monosulfides, six disulfides and four trisulfides; seven thiazoles, two thiophenes, five furanoids, including 2-methyL3(2H)furanone; five oxazoles, three oxazolines, including 2-methyl-3-oxazoline; 12 hydrocarbons, one alcohol, one ketone, two acids, two esters, 2-acetoxy-2-butene, and maltol.