Recommendations are made for handling and growth of Beneckea natriegens, a rapidly growing, nonpathogenic marine bacterium which can be used with advantage to replace Escherichia coli in many undergraduate microbiology experiments. Examples of experiments and the potential value of this organism as a subject for student research projects are…

Discusses human ability to perceive repeated sensory stimuli in the visual system, and explains that its frequency fc has a critical value, under normal conditions, about 40 Hz. (GA)

Describes an undergraduate physical chemistry experiment which demonstrates the principles of solution calorimetry and the entropy titration technique. (CS)

Describes large scale experiments to test the value of index term weighting based on relevance information, and presents results showing that weighting leads to remarkable improvements in retrieval performance. (Author/CWM)

A paradigm depicts research as a continuum along three major dimensions: utility--basic v applied; nature--theoretical v empirical; and causality--least v most experimental. (CP)

Presents three problems that can be used in classroom to motivate chemical engineering students at the college level. (HM)

Accidentally killed animals provide biology classes with excellent study material. (Editor)

Describes a two-hour physics laboratory experiment modeling the phenomena of eclipsing binary stars developed by the Air Force Academy as part of a week-long laboratory-oriented experience for visiting high school students. (BT)

Describes a simple demonstration that illustrates the nature of isotropic substances by tearing newsprint, magazines, and wrapping paper. (BT)

This article describes the distribution of mass in a hand-held object as a fundamental but unrecognized contributor to the sensation one receives from the object. Experiments producing fractions for human sensitivity are given. (SA)

Discusses electric and magnetic forces between parallel-wire conductors and derives, in a simple fashion, order of magnitude estimates of the ratio of the likely electrostatic and electromagnetic forces for a simple parallel-wire balance. (Author/HM)

Describes a nineteenth century paper by Reynolds on his experiments with the tension that a column of liquid could sustain, and compares Reynolds work with some of the other related work published in French journals at that time. (GA)

Discusses different approaches to the teaching of electrical resistance as presented by different authors of physics textbooks. Evaluates, compares, and expresses personal preferences for certain approaches. (GA)

Explains interference colors in thin films as being due to the removal, or considerable reduction, of a certain color by destructive inteference that results in the complementary color being seen. (GA)

An experiment is presented which utilizes the current solid state technology to demonstrate electrochemical generation of hydrogen gas, direct generation of electricity for pumping water, and energy conversion efficiency. The experimental module costs about $100 and can be used repeatedly. (BB)