The rewarding effects of number and surface area of food in rats

Visual cues have an important role in food preference for both rats and humans. Here, we aim to isolate the effects of numerosity, density, and surface area on food preference and running speed in rats, by using a forced-choice maze paradigm. In Experiment 1, rats preferred and ran faster for a group of multiple smaller pellets rather than a single large pellet, corroborating previous research (Capaldi, Miller, & Alptekin Journal of Experimental Psychology: Animal Behavior Processes, 15(1), 75–80, 1989). Further experiments tested the prevailing hypothesis that multiple food pieces are more reinforcing because they occupy a larger surface area. Experiment 2 controlled for numerosity by utilizing a continuous food: mashed potatoes flattened to cover a larger surface area or rounded into a ball. The rats preferred and ran faster for the flattened potatoes, suggesting surface area plays a role in quantity estimations. Finally, in Experiment 3, rats displayed no preference or difference in running speed between a group of scattered and clustered pellets when number of pellets were kept constant. Taken together, these results suggest that density has an important role in food perception—that is, the rewarding effect of higher numerosity or larger surface area is removed when the food does not fill out the entire space. Alternative explanations and implications for human diet are discussed.     

Fighting for Desired Versions of a Future Self: How Young Women Negotiated STEM-Related Identities in the Discursive Landscape of Educational Opportunity

In this article, we investigate how the national imperative to increase opportunities for young women of color in science, technology, engineering, and mathematics (STEM) and to broaden their participation was taken up locally at two high schools in one school district. Using ethnographic and longitudinal data, we focus on four young women of color (two at each school) as they negotiated STEM-related identities in the discursive and practice contexts of their lives at school. Using Holland and Lave’s concept of history in person, we view the young women as fighting for particular versions of a future self while entangled in discursive and social relations that threatened to position them differently than they wished to be. We find that their fight for future selves was not—for them—with the national narrative about women of color in STEM but with local school narratives that negatively positioned students of color more broadly and remained silent on issues of gender, the intersection of gender and race, and the implications for STEM. High school success in STEM came as a hopeful but potentially fragile byproduct of struggles to differentiate themselves from people like them (other Blacks, Latinas, the poor). Implications of these findings are discussed.     

Transistors — From point contact to single electron

This article presents a historical account of the development of electronic devices along with an appreciation for the physics of semiconductors. Starting at the turn of the century with the work of J C Bose on Galena, the article leads us to recent low temperature experiments at IBM to demonstrate single electron transistors.     

Market segmentation for improved distance education program planning

Distance education planners face two basic, yet difficult decisions: which students should be targeted and which programs should be offered? This paper reports the process and results of the planning committee of a consortium of engineering schools in the United States that was tasked with these very decisions. A market research study measured the program preferences of potential students. Three program characteristics (course type, delivery method, and time availability) were examined. The results show there is no ‘average’ student and no single program will satisfy all the needs of the student population. Rather, the committee must choose one or more segments based on the program preferences of the students and the resources required to provide the programs.