Exploring children's understanding of death concepts

This study is an investigation of the effects of death education on children and their understanding of death. The participants of this study were eighty 5- and 6-year-olds who were enrolled in a suburban kindergarten in Korea. To examine the level of children's understanding of death, researchers interviewed each child in both the control and experimental groups. After the interview, researchers provided an intervention (11 educational activities) to the experimental group. No educational intervention was provided to the control group. Researchers re-interviewed children in both groups after the treatment. The overall mean score of the experimental group was significantly higher than that of the control group on all five categories of the death concept: causality, old age, irreversibility, finality, and inevitability. Implications regarding how death education can be approached in early childhood settings are also discussed.     

How Does the Freezer Burn Our Food?

ABSTRACT:  Freezer burn is a common problem that significantly affects the color, texture, and flavor of frozen foods. Food science students should be able to clearly explain the causes and consequences of freezer burn. However, it is difficult to find a modern, detailed, accurate, yet concise, explanation of the mechanism and factors influencing the rate of freezer burn, suitable for classroom use. Thus, the purpose of this article is to provide students and instructors alike with such an explanation, replete with visual explanations, including 2 short animations. The animations, in QuickTime format, are available as supporting information and can be downloaded for free educational use.     

Discourses of Exclusion: Immigrant-Origin Youth Responses to Immigration Debates in an Election Year

Political discourse on immigration policy often provides a window into a society’s boundaries of inclusion and exclusion. Here, we seek to understand how those in liminal positions respond to political debates that raise issues of boundary maintenance. Drawing from Bakhtinian concepts of authoritative and internally persuasive discourses as well as Gramsci’s concept of common sense, we analyzed how a superdiverse sample of 26 immigrant-origin adolescents (from Asia, Latin America, Africa, and Europe) responded to video segments of presidential debates from the 2012 U.S. election. Youth’s responses to presidential video clips about undocumented immigration policies fell along a spectrum from inclusionary to exclusionary, with many voicing mixed responses to immigration policies. Half of the youth referenced their own family’s migration experience when discussing immigration policy, most frequently in empathetic ways; however, this did not preclude them from aligning with discourses of exclusion. The theme of fairness was prevalent in their responses, yet it emerged in distinct ways. This work highlights the need to interrogate common-sense discourses of exclusion.     

Development of Information Functions and Indices for the GGUM‐RANK Multidimensional Forced Choice IRT Model

This research derived information functions and proposed new scalar information indices to examine the quality of multidimensional forced choice (MFC) items based on the RANK model. We also explored how GGUM‐RANK information, latent trait recovery, and reliability varied across three MFC formats: pairs (two response alternatives), triplets (three alternatives), and tetrads (four alternatives). As expected, tetrad and triplet measures provided substantially more information than pairs, and MFC items composed of statements with high discrimination parameters were most informative. The methods and findings of this study will help practitioners to construct better MFC items, make informed projections about reliability with different MFC formats, and facilitate the development of MFC triplet‐ and tetrad‐based computerized adaptive tests.     

The Implications of Arendt's Concept of Judgment for Humanistic Teaching in a Postmetaphysical Age

In this essay, Duck‐Joo Kwak draws on Hannah Arendt's concept of judgment in exploring what it means to teach the humanities as a form of values education in a postmetaphysical age. Arendt's concept of judgment is closely related to Ciceronian humanism, which is concerned with the wisdom to choose one's company while appreciating this pursuit itself, among men, things, and thoughts from the past and present. According to Arendt, this wisdom as a form of judgment can be generated from a unique form of thinking via understanding. Thus, the main focus of this essay is on Arendt's explication of two distinct forms of humanistic thinking, which can be characterized as critical and interpretive, respectively. The educational virtue of humanistic thinking lies in its avoidance of both authoritarianism and nihilistic constructivism, both of which are problematic in the context of postmetaphysical contemporary culture, while also holding the potential to help young people find good company as a way of expanding the boundaries of intersubjectivity in their selfhood.     

Microfluidic size separation of cells and particles using a swinging bucket centrifuge

Biomolecular separation is crucial for downstream analysis. Separation technique mainly relies on centrifugal sedimentation. However, minuscule sample volume separation and extraction is difficult with conventional centrifuge. Furthermore, conventional centrifuge requires density gradient centrifugation which is laborious and time-consuming. To overcome this challenge, we present a novel size-selective bioparticles separation microfluidic chip on a swinging bucket minifuge. Size separation is achieved using passive pressure driven centrifugal fluid flows coupled with centrifugal force acting on the particles within the microfluidic chip. By adopting centrifugal microfluidics on a swinging bucket rotor, we achieved over 95% efficiency in separating mixed 20 μm and 2 μm colloidal dispersions from its liquid medium. Furthermore, by manipulating the hydrodynamic resistance, we performed size separation of mixed microbeads, achieving size efficiency of up to 90%. To further validate our device utility, we loaded spiked whole blood with MCF-7 cells into our microfluidic device and subjected it to centrifugal force for a mere duration of 10 s, thereby achieving a separation efficiency of over 75%. Overall, our centrifugal microfluidic device enables extremely rapid and label-free enrichment of different sized cells and particles with high efficiency.     

A numerical study on the dynamics of droplet formation in a microfluidic double T-junction

In this study, droplet formations in microfluidic double T-junctions (MFDTD) are investigated based on a two-dimensional numerical model with volume of fluid method. Parametric ranges for generating alternating droplet formation (ADF) are identified. A physical background responsible for the ADF is suggested by analyzing the dynamical stability of flow system. Since the phase discrepancy between dispersed flows is mainly caused by non-symmetrical breaking of merging droplet, merging regime becomes the alternating regime at appropriate conditions. In addition, the effects of channel geometries on droplet formation are studied in terms of relative channel width. The predicted results show that the ADF region is shifted toward lower capillary numbers when channel width ratio is less than unity. The alternating droplet size increases with the increase of channel width ratio. When this ratio reaches unity, alternating droplets can be formed at very high water fraction (wf = 0.8). The droplet formation in MFDTD depends significantly on the viscosity ratio, and the droplet size in ADF decreases with the increase of the viscosity ratio. The understanding of underlying physics of the ADF phenomenon is useful for many applications, including nanoparticle synthesis with different concentrations, hydrogel bead generation, and cell transplantation in biomedical therapy.     

dc electrokinetic transport of cylindrical cells in straight microchannels

Electrokinetic transport of cylindrical cells under dc electric fields in a straight microfluidic channel is experimentally and numerically investigated with emphasis on the dielectrophoretic (DEP) effect on their orientation variations. A two-dimensional multiphysics model, composed of the Navier–Stokes equations for the fluid flow and the Laplace equation for the electric potential defined in an arbitrary Lagrangian–Eulerian framework, is employed to capture the transient electrokinetic motion of cylindrical cells. The numerical predictions of the particle transport are in quantitative agreement with the obtained experimental results, suggesting that the DEP effect should be taken into account to study the electrokinetic transport of cylindrical particles even in a straight microchannel with uniform cross-sectional area. A comprehensive parametric study indicates that cylindrical particles would experience an oscillatory motion under low electric fields. However, they are aligned with their longest axis parallel to the imposed electric field under high electric fields due to the induced DEP effect.