Changes in velocity profile according to blood viscosity in a microchannel

Red blood cells (RBCs) are important to dictate hemorheological properties of blood. The shear-thinning effect of blood is mainly attributed to the characteristics of the RBCs. Variations in hemorheological properties alter flow resistance and wall shear stress in blood vessels. Therefore, detailed understanding of the relationship between the hemorheological and hemodynamic properties is of great importance. In this study, blood viscosity and blood flow were simultaneously measured in the same microfluidic device by monitoring the flow-switching phenomenon. To investigate blood flows according to hemorheological variations, the flow rate of blood samples (RBCs suspended in autologous plasma, dextran-treated plasma, and in phosphate buffered saline solution) was precisely controlled with a syringe pump. Velocity profiles of blood flows were measured by using a micro-particle image velocimetry technique. The shape of velocity profiles was quantified by using a curve-fitting equation. It is found that the shape of the velocity profiles is highly correlated with blood viscosity. To demonstrate the relationship under ex vivo conditions, biophysical properties and velocity profiles were measured in an extracorporeal rat bypass loop. Experimental results show that increased blood viscosity seems to induce blunt velocity profile with high velocity component at the wall of the microchannel. Simultaneous measurement of blood viscosity and velocity profile would be useful for understanding the effects of hemorheological features on the hemodynamic characteristics in capillary blood vessels.     

The Impact of Disordered Eating Behavior on College Relationships: A Qualitative Study

The authors explored how college students’ disordered eating behaviors affect their peers. Participants were 8 undergraduate students from a northeastern university with a peer who currently or previously engaged in eating disorder (ED) behaviors. Results from a consensual qualitative analysis provided preliminary evidence that students’ EDs negatively affect peers. Outreach and interventions such as cognitive behavior therapy could be used to assist peers of students with EDs. Researchers should investigate the impact of students’ ED behaviors on peers’ health and academic performance.     

“You Can Do it Anywhere”: Student and Teacher Perceptions of an Online Sexuality Education Intervention

Formal sexuality education in schools is declining in the United States and this is disproportionately affecting adolescents in rural settings. The purpose of this qualitative study was to assess student and teacher perception of sexuality education delivered online as a potential solution to address this gap in access. Nine gender-specific group interviews were conducted with ninth grade students (n = 29) in rural North Carolina to discuss students’ experience with an online sexuality education intervention called MyHealthEd. Interviews were also conducted with three health teachers at pilot schools. Students and teachers identified more benefits to online sexuality education including more student engagement and greater privacy and comfort, than drawbacks, such as too much student autonomy and less interaction with others. Online sexuality education is a promising and preferred method of delivery for sexuality education for students and health teachers, particularly in settings where trained health teachers are not available or less willing to deliver state-mandated content. The MyHealthEd intervention has the potential to increase availability of high quality health education to students across North Carolina, as well as students in other rural or underserved areas.     

Math fluency is etiologically distinct from untimed math performance, decoding fluency, and untimed reading performance: evidence from a twin study

The authors examined whether math fluency was independent from untimed math and from reading using 314 pairs of school-aged twins drawn from the Western Reserve Reading and Math Projects. Twins were assessed through a 90-min home visit at approximately age 10 and were reassessed in their homes approximately 1 year later. Results suggested that the shared environment and genetics influenced the covariance among math fluency, untimed math measures, and reading measures. However, roughly two thirds of the variance in math fluency was independent from untimed math measures and reading, including reading fluency. The majority of this independent variance was the result of genetic factors that were longitudinally stable across two measurement occasions. These results suggest that math fluency, although related to other math measures, may also be a genetically distinct dimension of mathematics performance.     

The basic tastants in aversion conditioning: Evidence for sensory preconditioning and not potentiation

In Experiment 1, a potentiation paradigm was used to test the relative influence of odor and taste with two 2 basic tastants (i.e., salt and sweet) in conditioned aversion learning. Experiment 1 showed that aversions to tastants (salt or sweet presented in a manner by which it could be tasted) were established only in subjects trained with the tastant, not the odor (i.e., salt or sweet presented in a manner by which it could not be tasted). Experiment 2 demonstrated, with a sensory preconditioning procedure, that the expression of an aversion to tastants was dependent on previous tastant experience prior to odor aversion training. These results suggest that while subjects can smell salt and sweet solutions, these odors are neither sufficient nor necessary for the expression of a conditioned tastant aversion.     

Comparison of Preschoolers' Narratives,the Classroom Book Environment,and Teacher Attitudes Toward Literacy Practices in Korea and the United States

This study investigated Korean and U.S. preschoolers’ personal and fictional narratives, their classroom book environments, and their teachers’ attitudes about reading aloud. The participants were 70 Korean and American 3- and 4-year-olds enrolled in 2 university lab preschools and their 4 teachers. The structures and content of the preschoolers’ personal and fictional narratives were analyzed. The teachers’ attitudes and practices about their language and literacy curriculum, including books provided in the classroom and selected for reading aloud, were examined for associations with preschoolers’ narrative productions. Research Findings: The content of preschoolers’ personal narratives and the structural levels of their fictional narratives differed between the 2 Korean and 2 U.S. classrooms. The classroom book environments in the Korean and U.S. classrooms also differed, with more fictional books displayed in the 2 U.S. classrooms than in the 2 Korean classrooms. The 2 Korean and 2 U.S. preschool teachers also held different attitudes about the use of fiction and nonfiction for read-aloud story sessions, and U.S. teachers allocated more time in their school day for reading aloud than did Korean teachers. Practice or Policy: U.S. preschoolers may profit from a greater balance between fiction and nonfiction books in the classroom. Korean children might benefit from more exposure to fiction and fantasy along with more practice in creating fictional narratives.     

A test of two methods for extinguishing Pavlovian conditioned inhibition

Two experiments were performed using rats in a conditioned suppression procedure to test two different methods for extinguishing Pavlovian conditioned inhibition. In both experiments, a target stimulus, X, was made inhibitory by giving discrimination training of the form A+ AX?. Then, in Experiment 1, an attempt was made to extinguish the inhibition conditioned to X by presenting nonreinforced occurrences of X, of AX, and of A. Testing for conditioned inhibition took the form B+ BX?. It was found that the extinction procedure did not weaken the inhibitory properties of X. Experiment 2 attempted to extinguish the inhibition conditioned to X by presenting X randomly and independently of the reinforcer, electric grid shock. This procedure appeared to weaken inhibition quickly and permanently.     

The effects of conditioned taste aversions on the acquisition and maintenance of schedule-induced polydipsia

Conditioned taste aversions produced a moderate, but transient, suppression of schedule-induced polydipsia. This suppression was greater and longer lasting when rats were offered a choice between water and the previously poisoned solution on the polydipsia baseline. A final experiment demonstrated that taste aversions were more effective in suppressing schedule-induced consumption when superimposed on a developing schedule-induced drinking baseline as opposed to a stable pattern of schedule-induced drinking. It was suggested that schedule-induced polydipsia is insensitive to conditioned taste aversions. This conclusion was discussed in terms of schedule-induced alcohol consumption and its potential as an animal model of alcoholism.     

Recent developments in microfluidic synthesis of artificial cell-like polymersomes and liposomes for functional bioreactors

Recent advances in droplet microfluidics have led to the fabrication of versatile vesicles with a structure that mimics the cellular membrane. These artificial cell-like vesicles including polymersomes and liposomes effectively enclose an aqueous core with well-defined size and composition from the surrounding environment to implement various biological reactions, serving as a diverse functional reactor. The advantage of realizing various biological phenomena within a compartment separated by a membrane that resembles a natural cell membrane is actively explored in the fields of synthetic biology as well as biomedical applications including drug delivery, biosensors, and bioreactors, to name a few. In this Perspective, we first summarize various methods utilized in producing these polymersomes and liposomes. Moreover, we will highlight some of the recent advances in the design of these artificial cell-like vesicles for functional bioreactors and discuss the current issues and future perspectives.     

Do sophisticated epistemic beliefs predict meaningful learning? Findings from a structural equation model of undergraduate biology learning

This study investigated the relationships among college students’ epistemic beliefs in biology (EBB), conceptions of learning biology (COLB), and strategies of learning biology (SLB). EBB includes four dimensions, namely ‘multiple-source,’ ‘uncertainty,’ ‘development,’ and ‘justification.’ COLB is further divided into ‘constructivist’ and ‘reproductive’ conceptions, while SLB represents deep strategies and surface learning strategies. Questionnaire responses were gathered from 303 college students. The results of the confirmatory factor analysis and structural equation modelling showed acceptable model fits. Mediation testing further revealed two paths with complete mediation. In sum, students’ epistemic beliefs of ‘uncertainty’ and ‘justification’ in biology were statistically significant in explaining the constructivist and reproductive COLB, respectively; and ‘uncertainty’ was statistically significant in explaining the deep SLB as well. The results of mediation testing further revealed that ‘uncertainty’ predicted surface strategies through the mediation of ‘reproductive’ conceptions; and the relationship between ‘justification’ and deep strategies was mediated by ‘constructivist’ COLB. This study provides evidence for the essential roles some epistemic beliefs play in predicting students’ learning.