The recent advent of high-performance computing hardware enables large-scale, multi-physics simulation that provides accurate physical pictures in various fields of study. In order to utilize the high-performance computing system more efficiently, the high-order numerical approximations have become one of the central themes in computational fluid dynamics (CFD) due to their potential in achieving highly accurate predictions in a limited memory capacity.The single-stage or single-step high-order temporal discretizations have shown great promise in delivering high-order temporal accuracy in fast performance. Fundamentally, the single-stage time integrators are based on a Taylor series in the time domain. Although its high performance, the single-stage time integrators are less attractive and less flexible compared to the multi-stage methods due to the complexities in calculating the coefficient of time-Taylor expansion, which usually demands the flux Jacobians and Hessians. This dissertation develops a new single-stage high-order temporal integrator under finite difference discretization. The proposed high-order temporal method is based on the Lax-Wendroff type time discretization, with an algorithmic extension that provides the system independence property. The new approach, called system-free (SF) method, furnishes ease of implementation as well as portability and flexibility of the single-stage time integration method while maintaining the accuracy and stability of the numerical solution.

Introduction: The platelet-to-lymphocyte ratio (PLR) is associated with the inflammatory response in various diseases. However, studies on the use of the PLR for the prognosis of elderly patients with severe trauma are lacking. In this study, we examined the relationship between the PLR and in-hospital mortality in elderly patients with severe trauma.

Methods: This retrospective observational study included elderly (≥65 years) patients who were admitted for severe trauma (as defined by an Injury Severity Score [ISS] ≥ 16) between January–December 2022. We conducted multivariate analysis to assess the association between the PLR and in-hospital mortality using logistic regression of relevant covariates. We also performed receiver operating characteristic curve analysis to examine the prognostic performance of the PLR forin-hospital mortality.

Results: Among the 222 patients included in the study, the in-hospital mortality rate was 19.4% (43). The PLR of non-survivors was lower than that of survivors (62.1 vs 124.5). The areas under the curve (AUC) of the Glasgow Coma Scale (GCS) score ≤12, ISS, hemoglobin level, and PLR for predicting in-hospital mortality were 0.730 (95% confidence interval [CI] 0.667–0.787), 0.771 (95% CI 0.710–0.824), 0.657 (95% CI 0.591–0.719), and 0.730 (95% CI 0.667–0.788), respectively. The AUC of the PLR was not significantly different from that of GCS score ≤12 and ISS for predicting in-hospital mortality. Multivariate analysis showed that the PLR was independently associated with in-hospital mortality (odds ratio: 0.993; 95% CI 0.987–0.999).

Conclusion: Low platelet-to-lymphocyte ratio is independently associated with in-hospital mortality in elderly patients with severe trauma.

Although it is common to assess the language proficiencies of nonnative speaker students using standardized tests in educational contexts where language proficiency tends to be considered a determiner of academic success, some studies have argued that language proficiency should instead be considered a concept of communicative competence (e.g., Bachman, 1990; Canale & Swain, 1980; Celce-Murcia et al., 1995). As these studies have noted, however, most Two-Way Immersion (TWI) research regarding students’ language proficiencies has been based on standardized tests (e.g., Lindholm-Leary, 2001; Oller & Eilers, 2002; Thomas & Collier, 2002). Although various studies have found that students in TWI programs demonstrated progress toward the goals of bilingualism and biliteracy development (e.g., Alanis, 2000; de Jong, 2004), the outcomes in terms of the non-English language development are not consistent (e.g., Ha, 2001; Kanagy, 2001; Kovelman et al., 2008). Therefore, this study attempts to explore an alternative way of assessing students’ language proficiencies beyond using standardized tests in order to better understand their bilingual development.

Based upon sociocultural theories of learning, this study adopts the concept of perceived proficiency, i.e., that language proficiency is perceived by participants who constitute learning through interaction. In particular, this study focuses on two bilingual teachers’ perceived proficiencies of students in a Korean/English TWI program. In addition, it works toward assessing students’ bilingual language proficiency by analyzing FLOSEM scores and students’ use of referential choices in order to examine the relationship with teachers’ perceived proficiencies. Last, this study investigates how teachers’ perceived proficiencies influence classroom practices using positioning theory.

The data used in this study were collected through video and audio recordings of classroom interactions (24 hours); four interviews (two with each teacher); and students’ narratives in both English and Korean (eight narratives; two narratives per student). For the investigation of teachers’ perceived proficiencies of students, 46 interview excerpts were selected based on the researchers’ questions about students’ language ability. Clancy’s (1995) categorization of lexical forms was used for the analysis of referential choice.

The findings revealed that the two teachers’ perceived language proficiencies of students were constructed according to the specific context, a Korean/English TWI classroom. Mainly, both teachers considered the acquisition of ‘content vocabulary’ or ‘content knowledge’ to be the main essential competence for a high level of proficiency in both languages. Along with the perceived proficiencies of students, the teachers’ self-perception about their own Korean proficiencies, particularly their lack of discipline-specific vocabulary, influenced turn-taking processes that may have afforded or constrained students the opportunity to participate during the Korean instructional time. However, a detailed analysis of students’ use of referential choices in both languages and the results of the FLOSEM test suggested student proficiencies that differed from the teachers’ perceived proficiencies. Referential choice involves distinctive language-specific characteristics for each language; yet the teachers did not observe the skillful use of referential choice in the narrative of a student who had not been recognized by the teachers as possessing content vocabulary and knowledge. Throughout the classroom observation video data recorded during the Korean instructional time, teachers’ perceived student language proficiencies played an important role in their designating more proficient students who could model for less proficient students, despite the fact that the more proficient student may not have been consistently proficient according to different ways of measuring proficiency.

On the basis of these findings, I discuss implications for theory and practice. Overall, I argue for various approaches to assessing bilingual students’ language proficiencies, particularly in educational contexts such as TWI programs, emphasizing the development of tools that enable teachers to expand the scope of their perceptions about students’ bilingual language proficiency to enhance students’ bilingual language development.

The atomic force microscope (AFM) has become an extremely powerful tool for biological and cell studies. Modified AFM probes have been designed to inject biomolecules (DNA, proteins, etc.) into living cells or extract target biomolecules expressed inside the cells. However, the need for statistically significant sample sizes makes data collection an extremely lengthy process. A complementary microfluidic device can decrease data collection time by flowing cells passed the probe tip and immobilizing them while the probe investigates or manipulates the cell. Microfluidic devices generally do not permit physical access to channels and the ability to add or remove material is restricted to designated inlets and outlets, endpoints in microfluidic devices. True open-access microfluidics suffers from low pressure and flow rate limitations and an inability to integrate multiple modules. This research demonstrates a microfluidic device which can encapsulate cells within droplets, immobilize droplets, and release droplets to collect and analyze. Sealing the device with a thin film of PDMS provides the liberty for a probe to inject, extract, or inspect material from any portion of the channels while providing a barrier to confine the fluid to within the channels during device operation.

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In this paper we provide a glimpse of the iterations of design, research and theorizing of a probability simulation tool, Probability Explorer, that have occurred over the past decade. We provide a brief description of the key features of the technology designed to allow young students opportunities to explore probabilistic situations. This is followed by details about several research observations made in multiple investigations of student explorations with this probability micro-world software package. We then explicate how research results suggest that a focus on a bidirectional interplay between theoretical distribution and empirical data can promote reasoning about probabilistic phenomena, and offer implications for instruction. The paper concludes with a discussion of a next generation innovation in the software for representing a theoretical distribution that we believe may promote better students reasoning about the bidirectional connection between theoretical distributions and empirical data.