A Comparative Study of Computer-Assisted Instruction Versus Classroom Training of Naval Technicians of Varying Aptitude Levels

Any discussion of computer-assisted instruction (CAI) cannot proceed very far without first examining the issue of programmed instruction (PI). CAI is a relatively recent development in the area of education and training, whereas PI enjoys a somewhat longer history. Nonetheless, PI lies at the very heart of CAI and forms the base on which CAI exists. CAI then, may be viewed as a mode or type of PI. B. F. Skinner\u27s work in the 1940\u27s with the principles of operant conditioning laid the groundwork for the concept of PI (Garner, 1966). Operant conditioning is a type of conditioning whereby an emitted response is reinforced. The reinforcement should increase the strength of the response and presumably increase the chances that the response will occur again (Munn, Fernald, & Fernald, 1972). Operant conditioning, in which an individual is conditioned to behave in the direction of a predetermined goal, is achieved through the contingent reinforcement of a series of steps. These steps of action are linked together in a chain of successive approximations. Each link of the chain approximates the end goal slightly more than the previous link. This chain of successive approximations is followed until the end behavior is achieved (Garner, 1966). In this respect, PI makes use of the sequencing of small successive steps and contingent reinforcement to achieve some desired end goal, namely, achieving the lesson objective. This Skinnerian or linear form of PI requires the student to proceed through a forward moving chain in a step-by-step fashion until the end behavior is achieved. The step-by-step sequence, as it pertains to PI, refers to the individual segments or frames of a PI lesson. Each frame might be considered one step of the entire PI lesson. These frames, which should flow logically from one to the next, should build upon each other and approximate the lesson objective. Periodically, progress should be monitored in order to assure that the student is comprehending the lesson material (Wilson & Tosti, 1972). Typically, this is accomplished by incorporating multiple choice or true/false questions within the PI lesson itself. By so doing, student performances can be checked and appropriate actions taken within the concept of reinforcement. Deterline (1962) argues that all learned behavior is based on, reinforcement. Individuals learn by acting on their environment and, in turn, are influenced by the consequences of their actions (Deterline, 1962). Then consequences strengthen behavior, reinforcement is said to have taken place

Duality and Pro-Spectra

Cofiltered diagrams of spectra, also called pro-spectra, have arisen in diverse areas, and to date have been treated in an ad hoc manner. The purpose of this paper is to systematically develop a homotopy theory of pro-spectra and to study its relation to the usual homotopy theory of spectra, as a foundation for future applications. The surprising result we find is that our homotopy theory of pro-spectra is Quillen equivalent to the opposite of the homotopy theory of spectra. This provides a convenient duality theory for all spectra, extending the classical notion of Spanier-Whitehead duality which works well only for finite spectra. Roughly speaking, the new duality functor takes a spectrum to the cofiltered diagram of the Spanier-Whitehead duals of its finite subcomplexes. In the other direction, the duality functor takes a cofiltered diagram of spectra to the filtered colimit of the Spanier-Whitehead duals of the spectra in the diagram. We prove the equivalence of homotopy theories by showing that both are equivalent to the category of ind-spectra (filtered diagrams of spectra). To construct our new homotopy theories, we prove a general existence theorem for colocalization model structures generalizing known results for cofibrantly generated model categories.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol4/agt-4-34.abs.htm

Acquisition of a Multi-User Thin Film Synthesis and Processing Facility

A state-of-the-art advanced materials synthesis and processing facility focusing on the growth and fabrication of ceramic- based thin film materials will be funded with the assistance of the Academic Research Infrastructure Program. The facility will include a multi-technique thin film materials synthesis chamber equipped with a microwave plasma source, effusion cells, electron beam evaporators, magnetron sputter sources, and a Kauffman ion source. Characterization capabilities will include in-situ reflection high energy electron diffraction (RHEED), mass spectrometry for controlling growth processes, X-ray photoelectron spectroscopy (XPS), and a novel Hall probe for in- situ film characterization. Three major areas of research will be impacted significantly by the facility, namely 1) solid state micro-sensors, 2) nanomechanics of materials, and 3) surfaces and interfaces in hetero-epitaxial oxide systems. In the sensor work, which has connections with local industry, the synthesis and processing of well-defined doped metal-oxide films will be developed with the goal of understanding and controlling the molecular scale mechanisms by which surface microstructure, dopant type, and operating temperature influence sensor performance. A broad based advanced materials synthesis and processing facility for the growth and fabrication of ceramic-based thin films will be operated for the study of solid state microsensors based on metal-oxide ceramic films. The nanomechanics of these ceramic thin films will be studied, as well as the surfaces and interfaces occurring in heteroepitaxial oxide systems

Gyrase inhibitors induce an oxidative damage cellular death pathway

Modulation of bacterial chromosomal supercoiling is a function of DNA gyrase-catalyzed strand breakage and rejoining. This reaction is exploited by both antibiotic and proteic gyrase inhibitors, which trap the gyrase molecule at the DNA cleavage stage. Owing to this interaction, doublestranded DNA breaks are introduced and replication machinery is arrested at blocked replication forks. This immediately results in bacteriostasis and ultimately induces cell death. Here we demonstrate, through a series of phenotypic and gene expression analyses, that superoxide and hydroxyl radical oxidative species are generated following gyrase poisoning and play an important role in cell killing by gyrase inhibitors. We show that superoxide-mediated oxidation of iron-sulfur clusters promotes a breakdown of iron regulatory dynamics; in turn, iron misregulation drives the generation of highly destructive hydroxyl radicals via the Fenton reaction. Importantly, our data reveal that blockage of hydroxyl radical formation increases the survival of gyrase-poisoned cells. Together, this series of biochemical reactions appears to compose a maladaptive response, that serves to amplify the primary effect of gyrase inhibition by oxidatively damaging DNA, proteins and lipids