Optofluidic characterization of marine algae using a microflow cytometer

The effects of global warming, pollution in river effluents, and changing ocean currents can be studied by characterizing variations in phytoplankton populations. We demonstrate the design and fabrication of a Microflow Cytometer for characterization of phytoplankton. Guided by chevron-shaped grooves on the top and bottom of a microfluidic channel, two symmetric sheath streams wrap around a central sample stream and hydrodynamically focus it in the center of the channel. The lasers are carefully chosen to provide excitation light close to the maximum absorbance wavelengths for the intrinsic fluorophores chlorophyll and phycoerythrin, and the excitation light is coupled to the flow cytometer through the use of an optical fiber. Fluorescence and light scatter are collected using two multimode optical fibers placed at 90-degree angles with respect to the excitation fiber. Light emerging from these collection fibers is directed through optical bandpass filters into photomultiplier tubes. The cytometer measured the optical and side scatter properties of Karenia b., Synechococcus sp., Pseudo-Nitzchia, and Alexandrium. The effect of the sheath-to-sample flow-rate ratio on the light scatter and fluorescence of these marine microorganisms was investigated. Reducing the sample flow rate from 200 μL/min to 10 μL/min produced a more tightly focused sample stream and less heterogeneous signals.     

Mother Goose and Mother Nature: Designing Stories to Communicate Information About Climate Change

Narratives have the ability to highlight climate change information in a relatable and engaging format. The purpose of the present investigation was to test the effects of five story structure types containing climate change information on perceived message effectiveness. Furthermore, we measured whether political affiliation moderated persuasive effectiveness of climate change messages among U.S. eligible voting adults (N = 594) who identified as Republican, Democrat, and Independent. The highest rated story overall was situated in the past, was realistic, and had clear moral values, indicating that certain appealing stories can serve as effective conduits for persuasive messages across the political spectrum. There were few differences between political affiliations, namely, that Democrats and Republicans rated messages differently on effectiveness when they differed on moral themes.     

Responding on a multiple variable-time variable-time schedule as a function of component duration

Five pigeons pecked lighted keys for food reinforcers delivered by a multiple variable-time 30-sec variable-time 2-min schedule. The duration of the components varied from 5 sec to 16 min. The rate of responding generated by the more favorable component schedule decreased as component duration increased to an intermediate value and then increased with additional increases in duration. The decrease confirmed a prediction of additive theories of behavioral contrast. The rate of responding generated by the less favorable component did not increase as component duration increased. This decrease may represent a floor effect or it may violate a prediction of one additive theory of contrast.     

The fragmented framework of legal protection for the gifted

A legal framework for resolving disputes in gifted education is slowly evolving. Legislation, court cases, due process hearings, administrative regulations, Letters of Findings issued by the Office for Civil Rights (OCR), negotiation, and mediation are the major components of this framework. The authors' thesis is that each state's legal framework should be constructed by sound legislation, and these statutes should then be used as the foundation to settle disputes in gifted education. A second premise is that the most economical and efficient method to settle disputes is to resolve them at the lowest level within the legal framework.     

First‐year Biology Students’ Understandings of Meiosis: An investigation using a structural theoretical framework

Meiosis is a biological concept that is both complex and important for students to learn. This study aims to explore first‐year biology students’ explanations of the process of meiosis, using an explicit theoretical framework provided by the Structure of the Observed Learning Outcome (SOLO) model. The research was based on responses of 334 first‐year biology students to practical and examination questions about meiosis, together with student interviews. Students’ written responses were coded, which resulted in a hierarchy of qualitatively different categories consistent with recent developments in the SOLO model. Most responses described a number of the less abstract elements of meiosis, but not in a coherent, relational manner, and interviews elucidated several areas of confusion about meiosis and its subordinate concepts. These findings are consistent with much previous research, and provide insights into both the use of the SOLO model as a research tool and students’ understandings of meiosis. In conjunction with previous research, the results of this study raise questions beyond its local context about the match between students’ apparent understandings and university expectations. The implications of the study relate to the use of terminology, the treatment of meiosis in textbooks, and some specific issues of pedagogy.     

A Study of Children’s Fears

In carefully examining the thesis of a paper by Anderson, Nelson, and Edgington (1984) concerning the socalled Fool’s Type IIa error, one realizes that certain fundamental statistical tenets have been overlooked or ignored. The purpose of the present paper is to discount the notion of a Fool’s Type IIa error under the Neyman-Pearson philosophy of testing statistical hypotheses and to highlight the need for improved statistical education related to hypothesis testing. If the importance of Type I and Type II errors cannot be quantified, then the Neyman-Pearson approach to hypothesis testing is of no value, and hence a Fool’s Type IIa error is irrelevant. If statistical testing errors are important and can be quantified, then adjustment for the Fool’s Type IIa error region is equivalent to increasing the probability of making a Type I error.