Showing papers by "University of California, Irvine published in 1988"

Cognition in practice : mind, mathematics, and culture in everyday life

Abstract: Most previous research on human cognition has focused on problem-solving, and has confined its investigations to the laboratory. As a result, it has been difficult to account for complex mental processes and their place in culture and history. In this startling - indeed, disco in forting - study, Jean Lave moves the analysis of one particular form of cognitive activity, - arithmetic problem-solving - out of the laboratory into the domain of everyday life. In so doing, she shows how mathematics in the 'real world', like all thinking, is shaped by the dynamic encounter between the culturally endowed mind and its total context, a subtle interaction that shapes 1) Both tile human subject and the world within which it acts. The study is focused on mundane daily, activities, such as grocery shopping for 'best buys' in the supermarket, dieting, and so on. Innovative in its method, fascinating in its findings, the research is above all significant in its theoretical contributions. Have offers a cogent critique of conventional cognitive theory, turning for an alternative to recent social theory, and weaving a compelling synthesis from elements of culture theory, theories of practice, and Marxist discourse. The result is a new way of understanding human thought processes, a vision of cognition as the dialectic between persons-acting, and the settings in which their activity is constituted. The book will appeal to anthropologists, for its novel theory of the relation of cognition to culture and context; to cognitive scientists and educational theorists; and to the 'plain folks' who form its subject, and who will recognize themselves in it, a rare accomplishment in the modern social sciences.

Introduction to theoretical neurobiology

Abstract: The human brain contains billions of nerve cells whose activity plays a critical role in the way we behave, feel, perceive, and think. This two-volume set explains the basic properties of a neuron - an electrically active nerve cell - and develops mathematical theories for the way neurons respond to the various stimuli they receive. Volume 1 contains descriptions and analyses of the principal mathematical models that have been developed for neurons in the past thirty years. It provides a brief review of the basic neuroanatomical and neurophysiological facts that will form the focus of the mathematical treatment. Tuckwell discusses the mathematical theories, beginning with the theory of membrane potentials. He then goes on to treat the Lapicque model, linear cable theory, and time-dependent solutions of the cable equations. He concludes with a description of Rall's model nerve cell. Because the level of mathematics increases steadily upward from Chapter Two, some familiarity with differential equations and linear algebra is desirable.

Work Role Transitions: A Study of American Expatriate Managers in Japan

Abstract: Throughout the course of a career, an individual must make numerous role transitions, instigated through such events as overseas transfers, domestic transfers, promotions, company reorganizations, and inter-company job changes. This paper examines the relationships between several variables and work role transition in the case of an overseas assignment to Japan. Role ambiguity and role discretion were found to influence work adjustment, while predeparture knowledge, association with local nationals, and family's adjustment were found to correlate with general adjustment of American expatriate managers in Japan.

A mutation in the age-1 gene in Caenorhabditis elegans lengthens life and reduces hermaphrodite fertility.

Abstract: age-1(hx546) is a recessive mutant allele in Caenorhabditis elegans that results in an increase in mean life span averaging 40% and in maximal life span averaging 60% at 20 degrees; at 25 degrees age-1(hx546) averages a 65% increase in mean life span (25.3 days vs. 15.0 days) and a 110% increase in maximum life span (46.2 days vs. 22.0 days for wild-type hermaphrodites). Mutant males also show extended life spans. age-1(hx546) is associated with a 75% decrease in hermaphrodite self-fertility as compared to the age-1+ allele at 20 degrees. Using two novel strategies for following the segregation of age-1, we present evidence that longer life results from a mutation in a single gene that increases the probability of survival at all chronological ages. The long-life and reduced-fertility phenotypes cosegregate and are tightly linked to fer-15, a locus on linkage group II. age-1(hx546) does not affect the timing of larval molts, the length of embryogenesis, food uptake, movement, or behavior in any way tested. Although age-1(hx546) lowers hermaphrodite self-fertility, it does not markedly affect the length of the reproductive period with all the increase in life expectancy due to an increase in the length of postreproductive life. In so far as we are aware, this mutant in age-1 is the only instance of a well-characterized genetic locus in which the mutant form results in lengthened fife. It is likely that the action of age-1 in lengthening life results not from eliminating a programmed aging function but rather from reduced hermaphrodite self-fertility or from some other unknown metabolic or physiologic alteration.

Multipotent precursors can give rise to all major cell types of the frog retina.

Abstract: A prospective lineage analysis was performed to determine the variety of cell types that could be formed by individual precursor cells of the developing frog retina. Fluorescent dextran was iontophoretically injected into single cells of the embryonic optic vesicle. After further development of the embryo, labeled descendants were observed in all three layers of the larval retina. Furthermore, different clones were composed of various combinations of all major cell types, including the glial Muller cells. Hence, single optic vesicle cells have the potential to form any type of retinal cell, suggesting that the interactions that specify the differentiation pathway of retinal cells must occur late in development.

Cell lineage analysis reveals multipotency of some avian neural crest cells.

Abstract: A major question in developmental biology is how precursor cells give rise to diverse sets of differentiated cell types. In most systems, it remains unclear whether the precursors can form many or all cell types (multipotent or totipotent), or only a single cell type (predetermined). The question of cell lineage is central to the neural crest because it gives rise to numerous and diverse derivatives including peripheral neurons, glial and Schwann cells, pigment cells, and cartilage. Although the sets of derivatives arising from different populations of neural crest cells have been well-documented, relatively little is known about the developmental potentials of individual neural crest cells. We have iontophoretically microinjected the vital dye, lysinated rhodamine dextran (LRD) into individual dorsal neural tube cells to mark unambiguously their descendants. Many of the resulting labelled clones consisted of multiple cell types, as judged by both their location and morphology. Cells as diverse as sensory neurons, presumptive pigment cells, ganglionic supportive cells, adrenomedullary cells and neural tube cells were found within individual clones. Our results indicate that at least some neural crest cells are multipotent before their departure from the neural tube.

Basic fibroblast growth factor prevents death of lesioned cholinergic neurons in vivo

Abstract: Cutting the axons of the cholinergic neurons that project to the hippocampal formation results in death of most of these cells1,2. Previous studies have shown that administration of nerve growth factor before or at the same time as the lesion will prevent this cell death3,4. Here we demonstrate that basic fibroblast growth factor (FGF) administered into the brain reduces the death of cholinergic neurons in the medial septum and diagonal band of Broca after transection of their axons, in both young adult and aged rats. Moreover, FGF can partially protect against death of cholinergic neurons even when administered two days after axonal transection. These results indicate a possible function for FGF in the normal support of basal forebrain cholinergic neurons, but its range of activity could be wider, for FGF also supports non-cholinergic neurons in vitro5,6, it is localized in many of the central nervous system neurons7, and it is found in relatively high concentrations in the brain8.

Computer-based systems for cooperative work and group decision making

Abstract: Application of computer and communications technology to cooperative work and group decision making has grown out of three traditions: computer-based communications, computer:based information service provision, and computer-based decision support. This paper reviews the group decision support systems (GDSSs) that have been configured to meet the needs of groups at work, and evaluates the experience to date with such systems. Progress with GDSSs has proved to be slower than originally anticipated because of shortcomings with available technology, poor integration of the various components of the computing package, and incomplete understanding of the nature of group decision making. Nevertheless, the field shows considerable promise with respect to the creation of tools to aid in group decision making and the development of sophisticated means of studying the dynamics of decision making in groups.

Contributions of Quisqualate and NMDA Receptors to the Induction and Expression of LTP

Abstract: The contributions of two subclasses of excitatory amino acid transmitter receptors to the induction and expression of long-term potentiation (LTP) were analyzed in hippocampal slices. The quisqualate/kainate receptor antagonist DNQX (6,7-dinitro-quinoxaline-2,3-dione) blocked 85% of the evoked field potential, leaving a small response that was sensitive to D-AP5 (D-2-amino-5-phosphonopentanoate), an N-methyl-D-aspartate (NMDA) receptor blocker. This residual D-AP5-sensitive response was of comparable size in control and previously potentiated inputs. High-frequency stimulation in the presence of DNQX did not result in the development of robust LTP. Washout of the drug, however, revealed the potentiation effect. Thus NMDA-mediated responses can induce, but are not greatly affected by, LTP; non-NMDA receptors, conversely, mediate responses that are not needed to elicit LTP but that are required for its expression.

Droplet vaporization model for spray combustion calculations

Abstract: The re-examination of the classical droplet vaporization model is made in order to develop the simple but sufficiently accurate calculation algorithm which can be used in spray combustion calculations. The new model includes the effects of variable thermophysical properties, non-unitary Lewis number in the gas film, the effect of the Stefan flow on heat and mass transfer between the droplet and the gas, and the effect of internal circulation and transient liquid heating. To evaluate the competing simplified models of the droplet heating, the more-refined, extended model of heat transfer within a moving circulating droplet is considered. A simplified, one-dimensional ‘effective conductivity’ model is formulated for the transient liquid heating with internal circulation. As an illustration, the dynamic and vaporization histories of the droplets injected into the steady and fluctuating hot air streams are analyzed.

Excitatory Amino Acid Neurotransmission: NMDA Receptors and Hebb-Type Synaptic Plasticity

Abstract: The study of excitatory amino acids as neurotransmitters has recently resulted in many new and fundamental concepts in neuroscience. Much of this progress centers upon the role of N-methyl-D-aspartate (NMDA) receptors in CNS synaptic transmission and plasticity. In this review, we describe the properties of the excitatory amino acid receptor classes, particularly those of the NMDA class, and indicate how properties of this receptor permit a unifying concept for understanding plasticity associated with development and learning. Excitatory amino acids, primarily L-glutamate and related derivatives, are the major excitatory neurotransmitters in the vertebrate CNS. Exten­ sive biochemical, anatomical and electrophysiological analysis has shown that in corticofugal, corticocortical, and other pathways, the excitatory amino acids have the essential properties indicative of neurotransmitters (for reviews see Fagg & Foster 1983, Fonnum 1984, Cotman & Monaghan 1987). The excitatory amino acids act through multiple receptor classes, of which the NMDA receptor class is the most well understood. NMDA

Evolution of a bacteria/plasmid association.

Abstract: Associations between bacteria and their accessory elements (viruses, plasmids and transposons) range from antagonistic to mutualistic. A number of previous studies have demonstrated that plasmid carriage reduces bacterial fitness in the absence of selection for specific functions such as antibiotic resistance. Many studies have demonstrated increased fitness of evolving microbial populations in laboratory environments, but we are aware of only one study in which fitness gains were partitioned between a plasmid and its host. Here, we examine the evolution of an association between a plasmid and its bacterial host. Carriage of the non-conjugative plasmid pACYC184 initially reduced the fitness of Escherichia coli B in the absence of antibiotic. We then cultured plasmid-bearing bacteria for 500 generations in the presence of antibiotic. The fitness of each combination of host and plasmid, with and without the culture history, was determined by competing it against a baseline strain. The results indicate adaptation by the host genome, but no plasmid adaptation. We also competed the evolved host, transformed with the baseline plasmid, against its isogenic plasmid-free counterpart. The plasmid now increased the fitness of its host.

Continuing worldwide increase in tropospheric methane, 1978 to 1987.

Abstract: The average worldwide tropospheric mixing ratio of methane has increased by 11 percent from 1.52 parts per million by volume (ppmv) in January 1978 to 1.684 ppmv in September 1987, for an increment of 0.016 + or - 0.001 ppmv per year. Within the limits of the present measurements, the global tropospheric mixing ratio for methane over the past decade is consistent either with a linear growth rate of 0.016 + or - 0.001 ppmv per year or with a slight lessening of the rate of growth over the past 5 years. No indications were found of an effect of the El Nino-Southern Oscillation-El Chichon events of 1982-83 on total global methane, although severe reductions were reported in the Pacific Northwest during that time period.The growth in tropospheric methane may have increased the water concentration in the stratosphere by as much as 28 percent since the 1940s and 45 percent over the past two centuries and thus could have increased the mass of precipitable water available for the formation of polar stratospheric clouds.

Sehwa: a software package for synthesis of pipelines from behavioral specifications

Abstract: A set of techniques for the synthesis of pipelined data paths is described, and Sehwa, a program that performs such synthesis, is presented. The task includes the generation of data paths from a data-flow graph along with a clocking scheme that overlaps execution of multiple tasks. Some design examples are given. Sehwa can find the minimum-cost design, the highest performance design, and other designs between these two in the design space. Sehwa is written in Franz Lisp and executes within minutes, for problems of practical size, on a VAX 11/750. >

Two classes of N-methyl-D-aspartate recognition sites: differential distribution and differential regulation by glycine.

Abstract: The N-methyl-D-aspartate (NMDA) receptor, a subtype of excitatory amino acid receptor, mediates synaptic responses in many regions of the central nervous system. This receptor plays a critical role in the mechanisms of both synaptic plasticity and excitotoxicity. Although these receptors were generally thought to be a single homogeneous receptor population, we report observations indicating that two anatomically distinct forms of the NMDA-receptor complex exist. (i) The distribution of NMDA receptors, as labeled by the NMDA agonist L-[3H]glutamate, differs from that obtained with the radiolabeled antagonist 3H-labeled 3-[(+/-)2-carboxypiperazine-4-yl]propyl-1-phosphonic acid [( 3H]CPP). Relative to L-[3H]glutamate, [3H]CPP binding is low in the striatum and septum and high in the thalamus and inner cerebral cortex. (ii) NMDA antagonists are relatively more potent than agonists at displacing L-[3H]glutamate binding in the thalamus and cerebral cortex; agonists are relatively more potent in the striatum and cerebellum. (iii) Glycine, which potentiates NMDA-receptor responses to glutamate, causes a greater percentage increase in L-[3H]glutamate binding to NMDA receptors in the thalamus and cerebral cortex than in the striatum, septum, and cerebellum. Radiolabeled NMDA-antagonist binding, in contrast, is inhibited by glycine. Thus, as observed for gamma-aminobutyric acid type A receptors, NMDA receptors have an agonist-preferring binding-site population and an antagonist-preferring binding site population. These may represent two distinct receptors and/or two interconverting forms. It could be of significant clinical importance if these two sites differ in their response to NMDA.

On automatic feature selection

Abstract: We review recent research on methods for selecting features for multidimensional pattern classification. These methods include nonmonotonicity-tolerant branch-and-bound search and beam search. We describe the potential benefits of Monte Carlo approaches such as simulated annealing and genetic algorithms. We compare these methods to facilitate the planning of future research on feature selection.

A Culturalist Theory of Political Change

Abstract: Eckstein introduces the political cultural approach as one of two viable options for theory in political science, the other being rational-choice theory. He then explains why the “cumulative socialization” process that he associates with culture leads to what he calls “expectations of continuity.” In short, since earlier learning builds on later learning, people acquire considerable inertia to their orientations toward the world and cannot easily accommodate rapid, extensive change. But, Eckstein acknowledges, if the cultural approach fails to incorporate change, it offers little help in explaining a world in which change is ubiquitous. Instead political culture theory predicts that certain changes are likely while others are not. For instance, people routinely alter their actions in efforts to maintain their preferred social patterns in moderately new situations. Particularly among the members of modern societies, for whom such new situations are common, Eckstein thinks that social patterns capable of accommodating considerable flexibility gradually develop. But new situations that confront people with large-scale contextual changes likely will overwhelm culture-bound creatures. Faced with such circumstances, people are apt to lapse into various forms of incoherent and fragmented reactions rather than deftly revising their actions in ways that maintain their social patterns. Thus revolutionary transformations through which societies attempt to realize unprecedented objectives are not likely to achieve their intended outcomes.

Structure of lamellar lipid domains and corneocyte envelopes of murine stratum corneum. An X-ray diffraction study

Abstract: The lipid of the outermost layer of the skin is confined largely to the extracellular spaces surrounding the corneocytes of the stratum corneum where it forms a multilamellar adhesive matrix to act as the major permeability barrier of the skin. Knowledge of the molecular architecture of these intercellular domains is important for understanding various skin pathologies and their treatment, percutaneous drug delivery, and the cosmetic maintenance of the skin. We have surveyed by X-ray diffraction the structure of the intercellular domains and the extracted lipids of murine stratum corneum (SC) at 25, 45, and 70 degrees C which are temperatures in the vicinity of known thermal phase transitions [Rehfeld, S. J., & Elias, P. M. (1982) J. Invest. Dermatol. 79, 1-3]. The intercellular domains produce lamellar diffraction patterns with a Bragg spacing of 131 +/- 2 A. Lipid extracted from the SC and dispersed in excess water does not produce a simple lamellar diffraction pattern at any temperature studied, however. This and other facts suggest that another component, probably a protein, must be present to control the architecture of the intercellular lipid domains. We have also obtained diffraction patterns attributable to the protein envelopes of the corneocytes. The patterns suggest a beta-pleated sheet organizational scheme. No diffraction patterns were observed that could be attributed to keratin.

Estimation of the affinities of allosteric ligands using radioligand binding and pharmacological null methods.

Abstract: The theoretical basis for using radioligand binding and pharmacological techniques to estimate the dissociation constants of drugs which interact allosterically with receptors is described. This theory predicts that an allosteric ligand changes the affinity of another ligand which binds at the primary recognition site on the receptor complex without affecting the binding capacity of the primary ligand. The magnitude of this effect depends on the amount of cooperativity (positive or negative) between the binding of ligands at the allosteric and primary recognition sites. It is possible to estimate the dissociation constant of an allosteric ligand by measuring its effect on the binding of a radioligand at a fixed concentration. In this situation, the dissociation constant of the allosteric ligand can be calculated from the concentration of ligand which causes half of its maximal effect on radioligand binding. The effects of an allosteric ligand on the pharmacological responses to an agonist can be attributed to changes in affinity and intrinsic efficacy of the agonist-receptor complex. If the agonist used in the pharmacological experiments has a large receptor reserve, or if the allosteric ligand only influences the affinity of the agonist, then the dissociation constant of the allosteric ligand can be calculated from the results of experiments in which the concentration of agonist required for half-maximal response (EC50) is measured in the presence of various concentrations of the allosteric ligand. If the agonist used in the pharmacological experiments is a partial agonist with little receptor reserve, then the shift in the EC50 of the agonist caused by the allosteric ligand may be dependent on the affinity of the agonist.

Thrombin modulates and reverses neuroblastoma neurite outgrowth

Abstract: Previous studies have shown that neuroblastoma cells and several types of primary neuronal cells in culture rapidly extend neurites when switched from serum-containing to serum-free medium. The present studies on cloned neuroblastoma cells show that thrombin blocked this spontaneous differentiation at 2 nM with a half-maximal potency of 50 pM. This required the catalytic activity of thrombin and was reversed upon thrombin removal. Thrombin also caused cells in serum-free medium to retract their neurites at equally low concentrations. Two other serine proteases, urokinase and plasmin, did not block or reverse neurite extension even at 100-fold higher concentrations. A specific assay for thrombin indicated that thrombin detected in serum-containing medium from neuroblastoma cultures was derived from serum and that it was likely responsible for much of the known capacity of serum to maintain neuroblastoma cells in a nondifferentiated state. This was supported by the finding that heparin addition reduced the thrombin concentration in serum-containing medium and stimulated neurite outgrowth from neuroblastoma cells in serum-containing medium. Studies on the ability of thrombin to modulate neurite outgrowth by other agents showed that it blocked and reversed the neurite outgrowth activity of two thrombin inhibitors: protease nexin-1 (which is identical to glial-derived neurite-promoting factor) and hirudin. Thrombin, however, did not block the neurite-promoting activity of dibutyryl cAMP or prostaglandin E1. These results suggest a specific role for thrombin in control of neurite outgrowth.

Experimental studies of pleiotropy and epistasis in escherichia coli. i. variation in competitive fitness among mutants resistant to virus t4.

Abstract: Mutants selected for novel phenotypes frequently exhibit maladaptive pleiotropic effects. One may reasonably ask whether these effects are properties of the novel phenotypes per se, or whether these effects depend upon the particular genotypes conferring the novel phenotypes. To address this issue, I examined an array of independent mutants, derived from Escherichia coli B, that were all completely resistant to the virus T4. Each resistant mutant had maladaptive pleiotropic effects, but there was highly significant variation in competitive fitness among mutants. The degree of reduction in competitive fitness was strongly associated with cross-resistance to virus T7 and with the inferred position of the mutated gene in a complex metabolic pathway. This variation in competitive fitness permits refinement of the resistant phenotype by selection among resistant genotypes. This mechanism complements refinement of the resistant phenotype by selection for epistatic modifiers of maladaptive pleiotropic effects.

Cephalometric analysis for diagnosis and treatment of obstructive sleep apnea.

Abstract: A detailed cephalometric analysis was conducted on lateral x-rays from 30 adult patients with obstructive sleep apnea (OSA) and 12 age- and sex-matched controls. Statistical findings show that OSA patients are different from controls in at least five ways: 1. Their tongue and soft palate are significantly enlarged. 2. The hyoid bone is displaced inferiorly. 3. The mandible is normal in size and position (no micrognathia or malocclusion), but the face is elongated by an inferior displacement of the mandibular body. 4. The maxilla is retropositioned and the hard palate elongated. 5. The nasopharynx is normal, but the oropharyngeal and hypopharyngeal airway is reduced in area by an average of 25%, a factor that could produce or enhance OSA symptoms. These data suggest that cephalometric evaluation could be useful when used with head and neck examination, polysomnographic and endoscopic studies to evaluate OSA patients, and to assist with the planning/surgical treatment for improvement of upper airway patency.

Rousseau's general will: a condorcetian perspective

Abstract: general will: (1) there is a common good; (2) citizens are not always accurate in their judgments about what is in the common good; and (3) when citizens strive to identify the common good and vote in accordance with their perceptions of it, the vote of the Assembly of the People can be taken to be the most reliable means for ascertaining the common good. We then show that Condorcet's (1785) model of collective judgment shares these assumptions with Rousseau and that understanding the implications of Condorcet's (1785) "jury theorem" enables us to clarify many of the most obscure aspects of Rousseau's treatment of the general will, including his discussion of the debilitating effects of factions and his confidence in the ability of the Assembly of the People to discern the general will by means of voting.

Learning from examples: generation and evaluation of decision trees for software resource analysis

Abstract: A general solution method for the automatic generation of decision (or classification) trees is investigated. The approach is to provide insights through in-depth empirical characterization and evaluation of decision trees for one problem domain, specifically, that of software resource data analysis. The purpose of the decision trees is to identify classes of objects (software modules) that had high development effort, i.e. in the uppermost quartile relative to past data. Sixteen software systems ranging from 3000 to 112000 source lines have been selected for analysis from a NASA production environment. The collection and analysis of 74 attributes (or metrics), for over 4700 objects, capture a multitude of information about the objects: development effort, faults, changes, design style, and implementation style. A total of 9600 decision trees are automatically generated and evaluated. The analysis focuses on the characterization and evaluation of decision tree accuracy, complexity, and composition. The decision trees correctly identified 79.3% of the software modules that had high development effort or faults, on the average across all 9600 trees. The decision trees generated from the best parameter combinations correctly identified 88.4% of the modules on the average. Visualization of the results is emphasized, and sample decision trees are included. >

Optimal robot plant planning using the minimum-time criterion

Abstract: A path planning technique is presented which produces time-optimal manipulator motions in a workspace containing obstacles. The full nonlinear equations of motion are used in conjunction with the actuator limitations to produce optimal trajectories. The Cartesian path of the manipulator is represented with B-spline polynomials, and the shape of this path is varied in a manner that minimizes the traversal time. Obstacle avoidance constraints are included in the problem through the use of distance functions. In addition to computing the optimal path, the time-optimal open-loop joint forces and corresponding joint displacements are obtained as functions of time. The examples presented show a reduction in the time required for typical motions. >

Foundations for the Arcadia environment architecture

Abstract: Early software environments have supported a narrow range of activities (programming environments) or else been restricted to a single “hard-wired” software development process. The Arcadia research project is investigating the construction of software environments that are tightly integrated, yet flexible and extensible enough to support experimentation with alternative software processes and tools. This has led us to view an environment as being composed of two distinct, cooperating parts. One is the variant part, consisting of process programs and the tools and objects used and defined by those programs. The other is the fixed part, or infrastructure, supporting creation, execution, and change to the constituents of the variant part. The major components of the infrastructure are a process programming language and interpreter, object management system, and user interface management system. Process programming facilitates precise definition and automated support of software development and maintenance activities. The object management system provides typing, relationships, persistence, distribution and concurrency control capabilities. The user interface management system mediates communication between human users and executing processes, providing pleasant and uniform access to all facilities of the environment. Research in each of these areas and the interaction among them is described.

Integrating planning, execution and monitoring

Abstract: IPEM, for Integrated Planning, Execution and Monitoring, provides a simple, clear and well defined framework to integrate these processes. Representation integration is achieved by naturally incorporating execution and monitoring information into [Chapman, 1987] tweak's partial plan representation. Control integration is obtained by using a production system architecture where IF-THEN rules, referred to as flaws and fixes, specify partial plan transformations. Conflict resolution is done using a scheduler that embodies the current problem solving strategy. Since execution and plan elaboration operations have been designed to be independently applicable, and execution of an action is a scheduling decision like any other, the framework effectively supports interleaving of planning and execution (IPE). This renders a local ability to replan after both unexpected events and execution failure. The framework has served as the basis for an implemented hierarchical, nonlinear planning and execution system that has been tested on numerous examples, on various domains, and has shown to be reliable and robust.

Sex Roles in Advertising: A Comparison of Television Advertisements in Australia, Mexico, and the United States:

Abstract: In the past, research has found that the portrayal of sex roles in advertising has not reflected equality or reality. Further, studies typically have examined only U.S. advertising, leaving open th...