James T. Wilkes

Encuesta nacional sobre la pérdida anual de colmenas de abejas manejadas durante 2014–2015 en los EEUU

Declines of pollinators and high mortality rates of honey bee colonies are a major concern, both in the USA and globally. Long-term data on summer, winter, and annual colony losses improve our understanding of forces shaping the viability of the pollination industry. Since the mass die-offs of colonies in the USA during the winter of 2006–2007, generally termed “Colony Collapse Disorder” (CCD), annual colony loss surveys have been conducted. These surveys gage colony losses among beekeepers of all operation sizes, recruited to participate via regional beekeeping organizations, phone calls, and postal mail. In the last three years, these surveys include summer and annual losses in addition to winter losses. Winter losses in this most recent survey include 5,937 valid participants (5,690 backyard, 169 sideline, and 78 commercial beekeepers), collectively managing 414,267 colonies on 1 October 2014 and constituting 15.1% of the estimated 2.74 million managed colonies in the USA. Annual losses are typically higher than either winter or summer losses, as they calculate losses over the entire year. Total reported losses were 25.3% [95% CI 24.7–25.9%] over the summer, 22.3% [95% CI 21.9–22.8%] over the winter, and 40.6% [95% CI 40.0–41.2%] for the entire 2014–2015 beekeeping year. Average losses were 14.7% [95% CI 14.0–15.3%] over the summer, 43.7% [95% CI 42.8–44.6%] over the winter, and 49.0% [95% CI 48.1–50.0%] over the entire year. While total winter losses were lower in 2014–2015 than in previous years, summer losses remained high, resulting in total annual colony losses of more than 40% during the survey period. This was the first year that total losses were higher in the summer than in the winter, explained in large part by commercial beekeepers reporting losses of 26.2% of their managed colonies during summer, compared to 20.5% during winter. Self-identified causes of overwintering mortality differed by operation size, with smaller backyard beekeepers generally indicating colony management issues (e.g., starvation, weak colony in the fall), in contrast to commercial beekeepers who typically emphasize parasites or factors outside their control (e.g., varroa, nosema, queen failure). More than two-thirds of all beekeepers (67.3%) had higher colony losses than they deemed acceptable.

Application-based modules using apprentice learning for CS 2

A typical Data Structures (CS 2) course covers a wide variety of topics: elementary algorithm analysis; data structures including dynamic structures, trees, tables, graphs, etc.; large programming projects; and more advanced object-oriented concepts. Integrating these topics into assignments is a challenging task; educators often duplicate work done by others in re-inventing such assignments. At the same time, these assignments and large programs take time to develop and are often changed from semester to semester to preclude cheating. We report on a project that provides modules containing many kinds of programming and lab assignments which can be re-used across semesters with accessible and exciting application-oriented materials. Our project is a collaboration between a research and teaching oriented private university, a teaching oriented public university, and a teaching oriented historically black university. This helps ensure that the modules will be accessible to nearly all student populations. The modules developed are available electronically as hyper-text documents.

Teaching OO methodology in a project-driven CS2 course

After we adopted an objects-first approach in CS1, we had to redesign our CS2 and data structures courses. This paper reports on our efforts to develop a project-driven CS2 course that expands on the object-oriented methodology introduced in the CS1 course. We focused on using collections and base classes in meaningful, large-scale projects helping students understand why these classes are important before concentrating on implementation in the subsequent data structures and algorithms course. We also introduce the concepts of design patterns and frameworks. This paper focuses on the OO methodology developed in the course; a companion paper [6] deals with pedagogical issues in using our approach.

Beyond objects-first: a project-driven CS2 course

After we adopted an objects-first approach in CS1, we had to redesign our CS2 and data structures courses. This paper reports on our efforts to develop a project-driven CS2 course that expands on the object-oriented methodology introduced in the CS1 course. We omitted some traditional data structures material and focused on using data structures in meaningful, large-scale projects that guided the course content. This helped students understand why these structures are important before concentrating on implementation in the subsequent data structures and algorithms course. This paper focuses on the pedagogical aspects of our CS2 course; a companion paper [4] discusses object-oriented methodology in more detail.

Scientific experimentation via the matching game

In traditional computer science curricula, students view program implementation as the end product and not the means to obtaining some further result. All too often students complete an implementation at the last minute, perform a minimal amount of testing and call the assignment done! This paper discusses an approach we have taken in our courses to have students use and develop programs as part of a scientific inquiry. In addition to causing students to perform more thorough testing, our approach also improves empirical and critical thinking skills.

Blending object-oriented design principles and software engineering practices into an undergraduate architecture simulator project

It is well understood pedagogically that students learn better through active involvement. Thus the use of architecture simulators can enhance student learning in a computer organization, assembly programming, or architecture course. A deeper understanding can be attained by having students actually construct an architecture simulator. This paper describes the object-oriented design of a junior-level architecture course project that centers around the construction of a PDP-11 simulator. In addition, since this is a substantial system to build, the project blends in a number of software development practices designed to expose students in a practical and subtle way to valuable software engineering principles.

YESS: a Y86 pipelined processor simulator

A popular approach to teaching computer organization and architecture is through the use of a simulator. Simulators enable students to experiment with machines that are unavailable or obsolete. Students gain an even deeper understanding of architecture by having to actually implement an architecture simulator. This paper discusses the Y86 simulator that students are required to implement during the lab component of a computer systems course. This project provides students with an in-depth understanding of pipelined processors and the opportunity to participate in the development of a relatively large software product.