Efficient capture of circulating tumor cells with a novel immunocytochemical microfluidic device

Ability to perform cytogenetic interrogations on circulating tumor cells (CTCs) from the blood of cancer patients is vital for progressing toward targeted, individualized treatments. CTCs are rare compared to normal (bystander) blood cells, found in ratios as low as 1:10⁹. The most successful isolation techniques have been immunocytochemical technologies that label CTCs for separation based on unique surface antigens that distinguish them from normal bystander cells. The method discussed here utilizes biotin-tagged antibodies that bind selectively to CTCs. The antibodies are introduced into a suspension of blood cells intending that only CTCs will display surface biotin molecules. Next, the cell suspension is passed through a microfluidic channel that contains about 9000 transverse, streptavidin coated posts. A CTC making contact with a post has the opportunity to engage in a biotin-streptavidin reaction that immobilizes the cell. Bystander blood cells remain in suspension and pass through the channel. The goal of the present study is to establish the technical performance of these channels as a function of antigen density and operating conditions, especially flow rate. At 18 μL/min, over 70% of cells are captured at antigen densities greater than 30 000 sites/cell while 50% of cells are captured at antigen densities greater than 10 000. It is found that lower flow rates lead to decreasing cell capture probabilities, indicating that some streamlines develop which are never close enough to a post to allow cell-post contact. Future modeling and streamline studies using computational fluid dynamics software could aid in optimization of channel performance for capture of rare cells.     

Student difficulty in constructing proofs: The need for strategic knowledge

The ability to construct proofs is an important skill for all mathematicians. Despite its importance, students have great difficulty with this task. In this paper, I first demonstrate that undergraduates often are aware of and able to apply the facts required to prove a statement but still fail to prove it. They thus fail to construct a proof because they could not use the syntactic knowledge that they had. By comparing doctoral students and undergraduates constructing proofs in abstract algebra, I have hypothesized four types of `strategic knowledge' – knowledge of how to choose which facts and theorems to apply – which the doctoral students appeared to possess and undergraduates did not. The doctoral students appeared to know the powerful proof techniques in abstract algebra, which theorems are most important, when particular facts and theorems are likely to be useful, and when one should or should not try and prove theorems using symbol manipulation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Community Engagement at an Emerging Academic Medical Library: A Three-Pronged Outreach Model

The Oakland University William Beaumont School of Medicine’s (OUWB) service-oriented mission and vision is reflected in all aspects of the school including its culture, curriculum, research, community engagement, and the OUWB Medical Library. Though starting informally, the OUWB Medical Library’s outreach program has matured and now sustains a wide array of activities each year. This outreach program has blossomed into a three-pronged model that is inclusive of activities and endeavors engaging the institution and local community: integrate, partner, and create. Among its successes and challenges, the library’s ongoing outreach efforts have showcased the value of libraries in promoting community health and meaningfully contributing to the institutional mission.     

Framing Wind Energy: Strategic Communication Influences on Journalistic Coverage

The dominance of political communication over an issue like wind energy has the power to overwhelm attempts to frame wind farming as a scientific or environmental issue in the mediated public sphere. Using regulation as the primary newsmaker, politicians instead of scientists or environmental organizations become journalists’ sources in framing the issue. Wind energy is a special issue that is framed in unique ways due to environmental, political, and industry ties. Contest framing ensues between institutional stakeholders to win favorable media coverage. Through a sociological lens, this analysis examines how contemporary political communications continue to influence the media through professional routines and relationships even in a scientifically grounded industry during a surge of public environmentalism. Comparisons of political, energy industry, and environmental advocacy communications show that political and energy industry frames dominate newspaper coverage of energy issues even when environmental and scientific issues are inherent to the story.     

Scaling Within Rather Than Scaling Up: Implications from Students' Experiences in Reforming Urban Middle Schools

This article uses urban middle school student's interviews to describe the instructional differences they faced each day and the effects of these differences on what they learned. Data from a cohort of nearly 200 students over two years revealed common definitions of how they wanted their teachers to act and the kinds of classroom activities they wanted to be engaged in. But more important, their observations revealed stark differences in their actual experiences. Too few students experienced the quality instruction they desired. Students praised teachers who were willing to help, were strict but nice, and were able to explain. They also wanted instructional settings where they were challenged by meaningful projects and experiments, worked more interdependently with their peers, and combined work with fun. We conclude from these student observations that reform efforts will be more successful in settings that nurture, maintain, and reinforce classrooms like those so aptly described by students and promote the spread of these classrooms by taking advantage of the talents of exemplary staff within buildings (i.e., scaling within).     

Undergraduate projects in mathematics

Conclusion We have claimed that project work introduces the student to a wide range of mathematical activities: critical reading, selection of material, mathematical exposition, talking about mathematics, formulation of problems, investigation of open problems, and so forth. It also encourages an active personal involvement in mathematics. Our aim in presenting this report has been to focus attention on some of the questions facing university mathematics teachers at this time, in the hope that others may be encouraged to seek their own answers.     

Book reviews

DIGITAL SENSATIONS: SPACE, IDENTITY, AND EMBODIMENT IN VIRTUAL REALITY. By Ken Hillis. Minneapolis: University of Minnesota Press, 1999; pp. xi + 271. $47.95 cloth; $18.95 paper.

THOMAS KUHN: A PHILOSOPHICAL HISTORY FOR OUR TIMES. By Steve Fuller. Chicago and London: The University of Chicago Press, 2000; pp. xvii + 472.

PROMETHEUS WIRED: THE HOPE FOR DEMOCRACY IN THE AGE OF NETWORK TECHNOLOGY. By Darin Barney. Chicago: Chicago University Press, 2000; pp. 340. $29.00.

DEWEY ON DEMOCRACY. By William R. Caspary. Ithaca, NY: Cornell University Press, 2000; pp. 256. $39.95.

THE ORGANIZING PROPERTY OF COMMUNICATION. By François Cooren. Philadelphia and Amsterdam: John Benjamins, 2000; pp. 272. $50.00.

CRAFTING SOCIETY: ETHNICITY, CLASS, AND COMMUNICATION THEORY. By Donald G. Ellis. Mahwah: Lawrence Erlbaum Associates, Publishers, 1999; pp. xvi + 229. $49.95.

PROGAY/ANTIGAY: THE RHETORICAL WAR OVER SEXUALITY. Ralph R. Smith and Russel R. Windes. Thousand Oaks, CA: Sage Publications, Inc., 2000; pp. xxiv + 240.

THEORIES OF CULTURE IN POSTMODERN TIMES. By Marvin Harris. Walnut Creek, CA: AltaMira Press, 1999; pp. 224. Cloth $62.00; Paper $22.95.

PRESIDENTIAL CRISIS RHETORIC AND THE PRESS IN THE POST‐COLD WAR WORLD. By Jim A. Kuypers. Westport, CT: Praeger, 1997; pp. xi + 242.     

Ecological Validity in Understanding Sport Performance: Some Problems of Definition

One of the most significant aspects of current sport psychology research is the trend toward developing the relationship between theoretical concepts and practical applications. There have been many recent calls for the development of specific experimental paradigms closely linked to critical features of movement control and social interaction within specific frames of reference such as competitive sport (e.g., Lee & Young, 1985; Martens, 1979). The concept of ecological validity has been proposed as a crucial element of this current research thrust, and this paper attempts to identify and define some of the more important criteria underpinning ecologically valid research in sport psychology. Vision and sport performance is used as an exemplary area of investigation in which problematic and specific issues are examined. The basis of this critique has important implications for other areas of interest in the application of the behavioral sciences to sport. It is concluded that much greater debate must be stimulated concerning this important methodological principle, and a preliminary definition is provided for this purpose as well as to aid in the process of research evaluation in sport psychology.     

Exploring Conceptual Integration in Student Thinking: Evidence from a case study

Two reasons are suggested for studying the degree of conceptual integration in student thinking. The linking of new material to existing knowledge is an important aspect of meaningful learning. It is also argued that conceptual coherence is a characteristic of scientific knowledge and a criterion used in evaluating new theories. Appreciating this ‘scientific value’ should be one objective when students learn about the nature of science. These considerations imply that students should not only learn individual scientific models and principles, but should be taught to see how they are linked together. The present paper describes the use of an interview protocol designed to explore conceptual integration across two college‐level subjects (chemistry and physics). The novelty here is that a single interview is used to elicit explanations of a wide range of phenomena. The potential of this approach is demonstrated through an account of one student's scientific thinking, showing both how she applied fundamental ideas widely, and also where conceptual integration was lacking. The value and limitations of using this type of interview as one means for researching conceptual integration in students' thinking are discussed.