Review Article: Recent advancements in optofluidic flow cytometer

There is an increasing need to develop optofluidic flow cytometers. Optofluidics, where optics and microfluidics work together to create novel functionalities on a small chip, holds great promise for lab-on-a-chip flow cytometry. The development of a low-cost, compact, handheld flow cytometer and microfluorescence-activated cell sorter system could have a significant impact on the field of point-of-care diagnostics, improving health care in, for example, underserved areas of Africa and Asia, that struggle with epidemics such as HIV∕AIDS. In this paper, we review recent advancements in microfluidics, on-chip optics, novel detection architectures, and integrated sorting mechanisms.     

A Comparison of Label Switching Algorithms in the Context of Growth Mixture Models

Simulation studies involving mixture models inevitably aggregate parameter estimates and other output across numerous replications. A primary issue that arises in these methodological investigations is label switching. The current study compares several label switching corrections that are commonly used when dealing with mixture models. A growth mixture model is used in this simulation study, and the design crosses three manipulated variables—number of latent classes, latent class probabilities, and class separation, yielding a total of 18 conditions. Within each of these conditions, the accuracy of a priori identifiability constraints, a priori training of the algorithm, and four post hoc algorithms developed by Tueller et al.; Cho; Stephens; and Rodriguez and Walker are tested to determine their classification accuracy. Findings reveal that, of all a priori methods, training of the algorithm leads to the most accurate classification under all conditions. In a case where an a priori algorithm is not selected, Rodriguez and Walker’s algorithm is an excellent choice if interested specifically in aggregating class output without consideration as to whether the classes are accurately ordered. Using any of the post hoc algorithms tested yields improvement over baseline accuracy and is most effective under two-class models when class separation is high. This study found that if the class constraint algorithm was used a priori, it should be combined with a post hoc algorithm for accurate classification.     

An NCME Instructional Module on Latent DIF Analysis Using Mixture Item Response Models

The purpose of this ITEMS module is to provide an introduction to differential item functioning (DIF) analysis using mixture item response models. The mixture item response models for DIF analysis involve comparing item profiles across latent groups, instead of manifest groups. First, an overview of DIF analysis based on latent groups, called latent DIF analysis, is provided and its applications in the literature are surveyed. Then, the methodological issues pertaining to latent DIF analysis are described, including mixture item response models, parameter estimation, and latent DIF detection methods. Finally, recommended steps for latent DIF analysis are illustrated using empirical data.     

Cognitive Attributes,Attention, and Self‐Efficacy of Adequate and Inadequate Responders in a Fourth Grade Reading Intervention

We examined cognitive attributes, attention, and self‐efficacy of fourth grade struggling readers who were identified as adequate responders (n = 27), inadequate responders with comprehension only deficits (n = 46), and inadequate responders with comprehension and word reading deficits (n = 52) after receiving a multicomponent reading intervention. We also included typical readers (n = 40). These four groups were compared on measures of nonverbal reasoning, working memory, verbal knowledge, listening comprehension, phonological awareness, and rapid naming as well as on teacher ratings of attention problems and self‐reported self‐efficacy. The two inadequate responder groups demonstrated difficulties primarily with verbal knowledge and listening comprehension compared to typical readers and adequate responders. Phonological awareness and rapid naming differentiated the two inadequate responder groups. In addition, both inadequate responder groups showed more attention problems and low self‐efficacy compared to typical readers.     

Pre-service teachers’ motivation,sense of teaching efficacy,and expectation of reality shock

The present study investigated how pre-service teachers’ motivation and their sense of teaching efficacy influence their expectation about reality shock during the first year of professional teaching. A total of 533 pre-service teachers at a state university in the US Midwest participated in this study. The results showed that the pre-service teachers’ expectation of reality shock was negatively related to teacher efficacy and intrinsic motivation while it was positively related to introjected and external motivation. The results of a hierarchical regression analysis revealed that pre-service teachers’ sense of efficacy and introjected motivation were strong predictors of their expectation of reality shock, when gender difference was controlled for. There was an interaction effect between intrinsic motivation and teachers’ sense of efficacy in predicting the reality shock expectation. We discussed the educational implications for future research in an endeavour to reduce the reality shock among novice teachers.     

Introduction of Molecular Methods into a Food Microbiology Curriculum

Maintaining current, relevant curriculum in undergraduate Food Microbiology courses is essential for training future experts in food quality and safety. Having an understanding of the fundamental techniques (for example, polymerase chain reaction [PCR]) that are used in the food industry and regulatory agencies is critical for students entering the workforce. The purpose of this study was to assess the efficacy of integrating molecular methods into an undergraduate Food Microbiology course in both lecture and laboratory settings. Modules on PCR and pulsed‐field gel electrophoresis (PFGE), both of which are currently used by government agencies and the food industry to investigate the presence and persistence of foodborne pathogens, were developed, introduced, and evaluated among 269 students over 4 y. Multiple teaching and learning styles were incorporated through (i) traditional lecture format on the basics of PCR and PFGE; (ii) hands‐on group activities to build upon the lecture instruction; (iii) performing PCR and PFGE in the laboratory; and (iv) group discussions to analyze results from laboratory exercises. Pre‐ and postinstruction evaluations revealed significant increases in understanding and application of both methods in lecture and laboratory settings as demonstrated by 0.60 and 0.51 mean normalized gains for respective PCR and PFGE lectures and 0.50 and 0.56 mean normalized gains in respective labs. Academic year significantly impacted score improvement, potentially due to hidden factors, such as previous exposure to material and student aptitude. This study provides the platform for successful introduction of molecular techniques in an undergraduate Food Microbiology course. The guidelines and materials developed by our group are publicly available for use by other institutions.