Spatially variant red blood cell crenation in alternating current non-uniform fields

Alternating-current (AC) electrokinetics involve the movement and behaviors of particles or cells. Many applications, including dielectrophoretic manipulations, are dependent upon charge interactions between the cell or particle and the surrounding medium. Medium concentrations are traditionally treated as spatially uniform in both theoretical models and experiments. Human red blood cells (RBCs) are observed to crenate, or shrink due to changing osmotic pressure, over 10 min experiments in non-uniform AC electric fields. Cell crenation magnitude is examined as functions of frequency from 250 kHz to 1 MHz and potential from 10 V_pp to 17.5 V_pp over a 100 μm perpendicular electrode gap. Experimental results show higher peak to peak potential and lower frequency lead to greater cell volume crenation up to a maximum volume loss of 20%. A series of experiments are conducted to elucidate the physical mechanisms behind the red blood cell crenation. Non-uniform and uniform electrode systems as well as high and low ion concentration experiments are compared and illustrate that AC electroporation, system temperature, rapid temperature changes, medium pH, electrode reactions, and convection do not account for the crenation behaviors observed. AC electroosmotic was found to be negligible at these conditions and AC electrothermal fluid flows were found to reduce RBC crenation behaviors. These cell deformations were attributed to medium hypertonicity induced by ion concentration gradients in the spatially nonuniform AC electric fields.     

A Conspiracy of Fishes,or, How We Learned to Stop Worrying About #GamerGate and Embrace Hegemonic Masculinity

Recently, the margins between gaming and feminism have become increasingly contentious (Salter & Blodgett, 2012 Salter, A., & Blodgett, B. (2012). Hypermasculinity & Dickwolves: The contentious role of women in the new gaming public. Journal of Broadcasting & Electronic Media, 56, 401–416. doi:10.1080/08838151.2012.705199[Taylor & Francis Online], [Web of Science ®] [Google Scholar]). This article addresses a cultural moment where masculine gaming culture became aware of and began responding to feminist game scholars by analyzing GamerGate conspiracy documents and social media discussions related to the now infamous “DiGRA fishbowl.” Worries about the opacity of academic practices and a disparaging of feminist knowledge-making practices dominate these documents. By looking at these discussions and practices through the lens of conspiracy theories (Fenster, 2008 Fenster, M. (2008). Conspiracy theories: Secrecy and power in American culture (2nd edition). Minneapolis, MN: University of Minnesota Press. [Google Scholar]; Hofstadter, 1952 Hofstadter, R. (1952). The paranoid style in American politics and other essays. Cambridge, MA: Harvard University Press. [Google Scholar]) and counterknowledge (Fiske, 1994 Fiske, J. (1994). Blackstream knowledge: Genocide. In Media matters: Everyday culture and political change. Minneapolis, MN: University of Minnesota Press. [Google Scholar]) we consider the broader meaning of GamerGate's attention to academia.     

Exploring Changes in Home Visitors’ Perspectives in the Context of a Professional Development Activity

Early Childhood Education Journal - Research-based professional development opportunities for early childhood home visitors are valuable to the Early Head Start-Home-Based Option (EHS-HBO) and to...     

Implementation and Assessment of Food Safety Educational Materials for Secondary and Postsecondary Education

Previous studies have reported on the inadequacy of youth knowledge and practice of food safety principles. The formal high school science classroom environment presents an opportunity to stimulate interest and increase knowledge in food safety with potential benefits to students in improved science literacy, development of life skills, and greater awareness of career opportunities. Previously developed educational materials, Foodborne Illness Outbreak Investigations for Food Safety Education, were evaluated for instruction by high school and community college science educators of various subject matters including foods, microbiology, disease, and chemistry courses. Educator feedback was favorable on measures of quality, implementation ease, and student engagement, with ratings greater than 3 on a 5‐point scale corresponding to “good” to “excellent.” A positive change in familiarity with food safety concepts for 4 groups of students, representing approximately 77% of the participants, was demonstrated by an overall increase, ranging from 4% to 14%, in correct responses to a test administered before and after exposure to the materials. There was variation in degree of change and the topics positively impacted for student groups by subject matter.     

Exploring Person Fit with an Approach Based on Multilevel Logistic Regression

The idea that test scores may not be valid representations of what students know, can do, and should learn next is well known. Person fit provides an important aspect of validity evidence. Person fit analyses at the individual student level are not typically conducted and person fit information is not communicated to educational stakeholders. In this study, we focus on a promising method for detecting and conveying person fit for large-scale educational assessments. This method uses multilevel logistic regression (MLR) to model the slopes of the person response functions, a potential source of person misfit for IRT models. We apply the method to a representative sample of students who took the writing section of the SAT (N = 19,341). The findings suggest that the MLR approach is useful for providing supplemental evidence of model–data fit in large-scale educational test settings. MLR can be useful for detecting general misfit at global and individual levels. However, as with other model–data fit indices, the MLR approach is limited in providing information regarding only some types of person misfit.     

The influence of professional development in gifted education on the frequency of instructional practices

Gifted education teacher training, licensure, certification, and degrees are ubiquitous in the Australia and abroad, and yet whether or not such training results in changes to classroom instructional practices remains unknown. The purpose of this study was to better understand the relationship between professional development in gifted education and the practices used by educators in the classroom. Two hundred and seventy-nine respondents who had completed one of three levels of teacher professional development completed the Classroom Practice Survey (Revised). The preregistered prediction for this study, that higher levels of professional development would result in higher levels of self-reported teacher practices, was not supported by the data, thereby drawing attention to the need for more research in this area and potential revisions to gifted education teacher professional development opportunities.