Preference and resistance to change in concurrent variable-interval schedules

Pigeons were trained on a multiple schedule in which separate concurrent schedules were presented in the two components of the schedule. During one component, concurrent variable-interval 40-sec variableinterval 80-sec schedules operated. In the second component, concurrent variable-interval 40-sec variableinterval 20-sec schedules operated. After stable baseline performance was obtained in both components, extinction probe choice tests were presented to assess preference between the variable-interval 40-sec schedules from the two components. The variable-interval 40-sec schedule paired with the variableinterval 80-sec schedule was preferred over the variable-interval 40-sec schedule paired with the variableinterval 20-sec schedule. The subjects were also exposed to several resistance-to-change manipulations: (1) prefeeding prior to the experimental session, (2) a free-food schedule added to timeout periods separating components, and (3) extinction. The results indicated that preference and resistance to change do not necessarily covary.     

Analysis of a laminar-flow diffusional mixer for directed self-assembly of liposomes

The present work describes the operation and simulation of a microfluidic laminar-flow mixer. Diffusive mixing takes place between a core solution containing lipids in ethanol and a sheath solution containing aqueous buffer, leading to self assembly of liposomes. Present device architecture hydrodynamically focuses the lipid solution into a cylindrical core positioned at the center of a microfluidic channel of 125 × 125-μm² cross-section. Use of the device produces liposomes in the size range of 100–300 nm, with larger liposomes forming at greater ionic strength in the sheath solution and at lower lipid concentration in the core solution. Finite element simulations compute the concentration distributions of solutes at axial distances of greater than 100 channel widths. These simulations reduce computation time and enable computation at long axial distances by utilizing long hexahedral elements in the axial flow region and fine tetrahedral elements in the hydrodynamic focusing region. Present meshing technique is generally useful for simulation of long microfluidic channels and is fully implementable using comsol Multiphysics. Confocal microscopy provides experimental validation of the simulations using fluorescent solutions containing fluorescein or enhanced green fluorescent protein.     

The 'mandarin-missionary' strategy: Robert Kennicott, Spencer Fullerton Baird and specimen collection in the Hudson's Bay Territory

In 1859, Robert Kennicott, one of the most promising specimen collectors and young naturalists in the United States, was dispatched to Hudson's Bay Territory by Spencer Fullerton Baird, the Assistant Secretary of the Smithsonian. Kennicott was chosen because of previous experience in Canada, the familiarity with biota of the American Midwest, and because he had a boundless, infectious, enthusiasm for natural history that was typical among Baird's closest protégées. Kennicott was a natural scientific envoy--or missionary--to the officers of the Hudson's Bay Company, and many officers were enthusiastically 'converted' to the cause of collecting and/or overseeing the collection of natural history specimens. Due to this collaboration between Baird, Kennicott and the officers of the Hudson's Bay Company, the Smithsonian became a leading center of Canadian natural history in the Western hemisphere.     

Effects of schoolwide cluster grouping and within-class ability grouping on elementary school students’ academic achievement growth

We evaluated the effects of one year of schoolwide cluster grouping on the academic achievement growth of gifted and non-identified elementary students using a piecewise multilevel growth model. Scores from 186 non-identified and 68 gifted students’ Measures of Academic Progress Reading and Math scores were examined over three school years. In 2008–2009 within-class ability grouping was used. In 2009–2010 schoolwide cluster grouping was implemented. In 2010–2011 students once again were grouped only within classrooms by ability and students identified as gifted were spread across all classrooms at each grade level. Results suggest that schoolwide cluster grouping influenced student performance in the year following its implementation, but only for mathematics and not the area of reading.     

The development of beginning mathematics teacher pedagogical content knowledge

Recent research efforts (Schmidt et al. in The preparation gap: teacher education for middle school mathematics in six countries, MSU Center for Research in Mathematics and Science Education, 2007) demonstrate that teacher development programs in high-performing countries offer experiences that are designed to develop both mathematical knowledge and pedagogical knowledge. However, identifying the nature of the mathematical knowledge and the pedagogical content knowledge (PCK) required for effective teaching remains elusive (Ball et al. in J Teacher Educ 59:389–407, 2008). Building on the initial conceptual framework of Magnusson et al. (Examining pedagogical content knowledge, Kluwer, Dordrecht, pp 95–132, 1999), we examined the PCK development for two beginning middle and secondary mathematics teachers in an alternative certification program. The PCK development of these two individuals varied due to their focus on developing particular aspects of their PCK, with one individual focusing on assessment and student understanding, and the other individual focusing on curricular knowledge. Our findings indicate that these individuals privileged particular aspects of their knowledge, leading to differences in their PCK development. This study provides insight into the specific aspects of PCK that developed through the course of actual instructional practice, providing a lens for future research in this area.     

Drunk and Alone in a K‐Mart Parking Lot: The Pedagogy of Simulations and Contemporary Attitudes Toward Drinking and Driving

This article introduces readers to the philosophy and design of team-based learning (TBL), a method developed by Dr. Larry Michaelsen that was influenced by literature in organizational psychology and pedagogy documenting what actually motivates adults to learn and how they master higher order learning skills. We describe how TBL was implemented in several criminal justice courses and illustrate how this method has drastically reduced student apathy, increased attendance, improved performance, and eliminated frustration for both instructors and students. Additionally, we reflect on how this method has reshaped our roles as educators.     

The Media and Criminologists: Interactions and Satisfaction

Traditionally, academic criminologists have addressed two audiences—other academics and students—while largely ignoring other segments of society. Frequently neglected is attention to educating the public. This paper uses a random sample of American Society of Criminology (ASC) members to measure the level of interaction with and attitudes toward criminologists working with the media. Findings suggest that most criminologists have participated in an isolated incidence of working with the media, tend to be generally satisfied with this experience, and perceive working with the media as a worthwhile endeavor for criminologists.