Toward the Development of Semantically-Based Search Systems

Over the past several years, we have conducted a number of empirical studies focusing on the performance of human search intermediaries and indexers. Based on insights from these studies, we have developed a computerized intermediary system (EP-X) that represents document contents as frames, and that uses knowledge-based search tactics to assist information seekers in exploring the contents of such frame-based document databases. Below, we present for discussion several propositions based on our experiences in studying human experts and in building computerized intermediaries

Toward the Development of Semantically-Based Search Systems

Over the past several years, we have conducted a number of empirical studies focusing on the performance of human search intermediaries and indexers. Based on insights from these studies, we have developed a computerized intermediary system (EP-X) that represents document contents as frames, and that uses knowledge-based search tactics to assist information seekers in exploring the contents of such frame-based document databases. Below, we present for discussion several propositions based on our experiences in studying human experts and in building computerized intermediaries

Excitotoxicity Triggered by Neurobasal Culture Medium

Neurobasal defined culture medium has been optimized for survival of rat embryonic hippocampal neurons and is now widely used for many types of primary neuronal cell culture. Therefore, we were surprised that routine medium exchange with serum- and supplement-free Neurobasal killed as many as 50% of postnatal hippocampal neurons after a 4 h exposure at day in vitro 12–15. Minimal Essential Medium (MEM), in contrast, produced no significant toxicity. Detectable Neurobasal-induced neuronal death occurred with as little as 5 min exposure, measured 24 h later. D-2-Amino-5-phosphonovalerate (D-APV) completely prevented Neurobasal toxicity, implicating direct or indirect N-methyl-D-aspartate (NMDA) receptor-mediated neuronal excitotoxicity. Whole-cell recordings revealed that Neurobasal but not MEM directly activated D-APV-sensitive currents similar in amplitude to those gated by 1 µM glutamate. We hypothesized that L-cysteine likely mediates the excitotoxic effects of Neurobasal incubation. Although the original published formulation of Neurobasal contained only 10 µM L-cysteine, commercial recipes contain 260 µM, a concentration in the range reported to activate NMDA receptors. Consistent with our hypothesis, 260 µM L-cysteine in bicarbonate-buffered saline gated NMDA receptor currents and produced toxicity equivalent to Neurobasal. Although NMDA receptor-mediated depolarization and Ca2+ influx may support survival of young neurons, NMDA receptor agonist effects on development and survival should be considered when employing Neurobasal culture medium

Social Darwinism in Anglophone Academic Journals: A Contribution to the History of the Term

This essay is a partial history of the term ‘Social Darwinism’. Using large electronic databases, it is shown that the use of the term in leading Anglophone academic journals was rare up to the 1940s. Citations of the term were generally disapproving of the racist or imperialist ideologies with which it was associated. Neither Herbert Spencer nor William Graham Sumner were described as Social Darwinists in this early literature. Talcott Parsons (1932, 1934, 1937) extended the meaning of the term to describe any extensive use of ideas from biology in the social sciences. Subsequently, Richard Hofstadter (1944) gave the use of the term a huge boost, in the context of a global anti-fascist war.Peer reviewe