High-throughput size-based rare cell enrichment using microscale vortices

Cell isolation in designated regions or from heterogeneous samples is often required for many microfluidic cell-based assays. However, current techniques have either limited throughput or are incapable of viable off-chip collection. We present an innovative approach, allowing high-throughput and label-free cell isolation and enrichment from heterogeneous solution using cell size as a biomarker. The approach utilizes the irreversible migration of particles into microscale vortices, developed in parallel expansion-contraction trapping reservoirs, as the cell isolation mechanism. We empirically determined the critical particle∕cell diameter D(crt) and the operational flow rate above which trapping of cells∕particles in microvortices is initiated. Using this approach we successfully separated larger cancer cells spiked in blood from the smaller blood cells with processing rates as high as 7.5×10(6) cells∕s. Viable long-term culture was established using cells collected off-chip, suggesting that the proposed technique would be useful for clinical and research applications in which in vitro culture is often desired. The presented technology improves on current technology by enriching cells based on size without clogging mechanical filters, employing only a simple single-layered microfluidic device and processing cell solutions at the ml∕min scale.     

Accuracy of an infrared LED device to measure heart rate and energy expenditure during rest and exercise

The purpose of this study was to examine the accuracy of the ePulse Personal Fitness Assistant, a forearm-worn device that provides measures of heart rate and estimates energy expenditure. Forty-six participants engaged in 4-minute periods of standing, 2.0 mph walking, 3.5 mph walking, 4.5 mph jogging, and 6.0 mph running. Heart rate and energy expenditure were simultaneously recorded at 60-second intervals using the ePulse, an electrocardiogram (EKG), and indirect calorimetry. The heart rates obtained from the ePulse were highly correlated (intraclass correlation coefficients [ICCs] ≥0.85) with those from the EKG during all conditions. The typical errors progressively increased with increasing exercise intensity but were <5 bpm only during rest and 2.0 mph. Energy expenditure from the ePulse was poorly correlated with indirect calorimetry (ICCs: 0.01-0.36) and the typical errors for energy expenditure ranged from 0.69-2.97 kcal · min(-1), progressively increasing with exercise intensity. These data suggest that the ePulse Personal Fitness Assistant is a valid device for monitoring heart rate at rest and low-intensity exercise, but becomes less accurate as exercise intensity increases. However, it does not appear to be a valid device to estimate energy expenditure during exercise.     

Book Publishers Should Support Changes in the Office of the Copyright and the Register of the Copyright Office

The U.S. Copyright Office and the Register of Copyrights supervise a myriad of major functions, from recording a copyright to providing the U.S. Congress with reports and suggestions regarding the state of the law. Yet this office is part of the Library of Congress, which controls its budget and appoints the Register. Should the book publishing community support the creation of an Office of Copyrights as a separate agency of the U.S. Government? What can or should the book publishing community do to address these issues and questions? This article explores the development of the Copyright Office, the Register of Copyrights, and provides some suggestions and recommendations.     

The Kirtsaeng and SCI-HUB Cases: The Major U.S. Copyright Cases in the Twenty-First Century

There has been a plethora of substantive copyright cases in the history of the United States. Two of the most important cases in the last few years were: the Kirtsaeng case before the Supreme Court of the United States; and the SCI-HUB case before the United States District Court in the Southern District of New York. This paper addressed the key copyright issues raised in each case, including a discussion of relevant sections of the Copyright Law of the United States (17 U.S.C.) as well as suggestions the book and scholarly journal industries could consider addressing the insidious impact of copyright violations.     

Evaluation of a Design Principle for Fostering Students’ Epistemological Views on Models and Modelling Using Authentic Practices as Contexts for Learning in Chemistry Education

Science education should foster students’ epistemological view on models and modelling consistent with formal epistemology in science and technology practices. This paper reports the application of a curriculum unit in the classroom using an authentic chemical practice, ‘Modelling drinking water treatment’, as the context for learning. An authentic practice is defined as professionals working on an issue guided by common motives and purposes, according to a similar type of procedure and applying relevant knowledge. The epistemology on models and modelling in the practice was analysed and anchored in the curriculum unit. The knowledge involved was captured in a design principle ‘content modelling’. A design principle provides heuristic guidelines to reach the intended pedagogic effects in the classroom. Throughout the field tests, research data were collected by means of classroom observations, interviews, audio‐taped discussions, completed worksheets, and written questionnaires. Students were able to evaluate the advanced model features of goodness of fit and reliability, and, to a lesser extent, validity. However, reflection on the modelling approach applied can be improved. The findings were used to reconsider the current completion of the design principle ‘content modelling’. This study contributes to the acquisition of a knowledge base concerning the use of authentic practices as contexts for learning in chemistry education as well as in science education in a broader sense.     

Effect of worked examples and Cognitive Tutor training on constructing equations

Algebra students studied either static-table, static-graphics, or interactive-graphics instructional worked examples that alternated with Algebra Cognitive Tutor practice problems. A control group did not study worked examples but solved both the instructional and practice problems on the Cognitive Tutor (CT). Students in the control group requested fewer hints and made fewer errors on the CT practice problems but required more learning time on the instructional examples. There was no difference among the four groups in constructing equations on a paper-and-pencil posttest or on a delayed test that included training and transfer problems. However, students who studied worked examples with a table were best at identifying the meaning of the equation components. The concept of transfer-appropriate processing (the overlap between instructional task and assessment task) aided our interpretation of the findings. Although the CT had a short-term effect on reducing errors and hint requests on CT practice problems, the worked examples were as effective on delayed paper-and-pencil tests. The subsequent construction of a new module for the Animation Tutor (Reed and Hoffman, Animation Tutor: Mixtures. Instructional software, 2011) used both the interactive-graphics and static-table worked examples to take advantage of the complementary strengths of different representations (Ainsworth, Learn Instr 16:183–198, 2006).     

Examining Student Digital Artifacts During a Year-Long Technology Integration Initiative

This study was situated within a year-long, statewide technology integration initiative designed to support technology integration within science, technology, engineering, and math classrooms. It examined the elements used in student artifacts in an attempt to investigate trends in digital artifact creation. Among several conclusions, this examination highlighted areas of significant improvement in student use of technology, such as an increase in the creation of PowerPoint presentations and the inclusion of multimedia elements. The study also highlighted areas for improvement, such as the low cognitive demand for content in the majority of the artifacts.