Spaced Practice and Second Language Vocabulary Learning

This thesis aims to investigate whether learners can increase second or foreign language (L2) vocabulary learning through spaced practice, in which repeated practice is spaced out in time or through other intervening events. It is well acknowledged that spaced practice promotes learning and enhances retention. Despite robust positive effects of spaced practice in learning and memory, the degree to which spaced practice effects are meaningful for L2 learning is still not clear. For example, the majority of spaced practice studies on L2 vocabulary learning has focused on paired-associate learning (e.g., flashcard learning). There are many different learning activities for vocabulary learning, and more research investigating the effects of spaced practice in different vocabulary learning conditions is warranted. This thesis is made up of three studies in the integrated article format and is organized into five chapters: An introduction to the topic of spaced practice (Chapter 1), the three studies (Chapters 2, 3, and 4), and a concluding chapter (Chapter 5). Study 1 (Chapter 2) meta-analyzed earlier studies of spaced practice in L2 learning. 98 effect sizes from 48 experiments (N = 3,411) were retrieved. This study compared the effects of three aspects of spacing (spaced vs. massed, longer vs. shorter spacing, and equal vs. expanding spacing) on immediate and delayed posttests to calculate mean effect sizes. This study also examined the extent to which nine empirically motivated variables moderated the effects of spaced practice. Results showed that (a) spacing had a medium-to-large effect on L2 learning; (b) shorter spacing was as effective as longer spacing in immediate posttests but was less effective in delayed posttests than longer spacing; (c) equal and expanding spacing were statistically equivalent; and (d) variability in spacing effect size across studies was explained methodologically by the learning target, number of sessions, type of practice, activity type, feedback timing, and retention interval. This study has already been published in the journal Language Learning (Wiley). Study 2 (Chapter 3) examined the effects of spaced practice on L2 vocabulary learning through fill-in-the-blanks and flashcards activities. 150 Korean learners were divided into five groups: one control (no treatment) and four experimental groups, based on learning condition (fill-in-the-blanks vs. flashcards) and spacing type (massed [no spacing interval] vs. spaced [1-day interval]). The participants studied forty-eight low frequency English words. Results showed that the effects of spaced practice were greater for fill-in-the-blanks than flashcards on an immediate posttest and that spaced practice was more effective than massed practice for both activities on a 2-week delayed posttest. The results suggest that fill-in-the-blanks may be affected by spacing in the same way as flashcards. This study is currently under review at the journal Studies in Second Language Acquisition (Cambridge University Press). Study 3 (Chapter 4) examined the effects of spaced practice on the learning and retention of forty-eight low frequency English words through sentence production and flashcards activities. 150 Korean university students were randomly assigned to five groups: one control (no treatment) and four experimental groups, based on learning condition (sentence production versus flashcards) and spacing schedule (massed [no interval] versus spaced [1-day interval]). Results showed that spaced practice was as effective as massed practice in vocabulary learning for sentence production and flashcards activities on an immediate posttest but that spaced practice was more effective than massed practice for both activities on a 2-week delayed posttest. This suggests that both activities may be affected similarly by spacing. This study is currently under review at the journal TESOL Quarterly (Wiley). Taken as a whole, the current thesis showed large effects of spaced practice on L2 vocabulary learning and retention but the effects seemed to depend on how words were learned (e.g., whether the practice is spaced within a session or between multiple sessions; whether retrieval practice is provided or not). The thesis also showed that spaced practice may contribute to vocabulary learning in other ways apart from flashcards. Pedagogically, the findings suggest that it may be useful for teachers and students to use spacing when scheduling activities for practice repetitions inside and outside classroom. The findings of the three studies in the current thesis are important because they show the value of spacing in other L2 vocabulary learning conditions. This thesis then concludes with methodological and pedagogical implications for L2 vocabulary learning as well as suggestions for future research

Association between Obesity and Physical Fitness, and Hemoglobin A1c Level and Metabolic Syndrome in Korean Adults

BACKGROUND: The purpose of the current study was to investigate the association of obesity level, physical fitness level, hemoglobin A1c (HbA1c) level and metabolic syndrome (MetS) risk factors among Korean adults. METHODS: A total of 557 adults (272 males and 285 females) who underwent medical check-up at local hospital were recruited. In addition to regular health check-up, cardiopulmonary fitness, muscular endurance were measured and their association were analyzed. RESULTS: The prevalence of MetS was 31.7% for males and 23.7% for females. Females with the higher muscular endurance had lower waist circumference, triglyceride level, and HbA1c level than those with the lower muscular endurance. Males with the higher level of cardiopulmonary fitness had lower diastolic blood pressure, lower high-sensitivity C-reactive protein level and higher high density lipoprotein cholesterol level than males with the lower level of cardiopulmonary fitness. Females with the higher level of cardiopulmonary fitness had lower body weight, body mass index, systolic blood pressure, and fasting blood glucose level than females with the lower level of cardiopulmonary fitness. Participants with the higher level of adiposity and the lower level of physical fitness were 5.26 times (95% confidence interval [CI], 2.19 to 12.62), 5.71 times (95% CI, 2.23 to 14.60) more likely to have MetS, respectively, in male and female compared to participants who were neither obese nor have the lower level of fitness. CONCLUSION: This study suggests that maintaining a healthy body weight as well as a certain level of fitness is important for the prevention of MetS.ope

Vitamin D and Exercise Are Major Determinants of Natural Killer Cell Activity, Which Is Age- and Gender-Specific

BackgroundThe coronavirus-19 disease (COVID-19) pandemic reminds us of the importance of immune function, even in immunologically normal individuals. Multiple lifestyle factors are known to influence the immune function.ObjectiveThe aim was to investigate the association between NK cell activity (NKA) and multiple factors including vitamin D, physical exercise, age, and gender.MethodsThis was a cross-sectional association study using health check-up and NKA data of 2,095 subjects collected from 2016 to 2018 in a health check-up center in the Republic of Korea. NKA was measured using the interferon-γ (IFN-γ) stimulation method. The association of NKA with 25-(OH)-vitamin D (25(OH)D) and other factors was investigated by multiple logistic regression analysis.ResultsThe average age of subjects was 48.8 ± 11.6 years (52.9% of subjects were female). Among 2,095 subjects, 1,427 had normal NKA (NKA ≥ 500 pg IFN-γ/mL), while 506 had low NKA (100 ≤ NKA < 500 pg/mL), and 162 subjects had very low NKA (NKA < 100 pg/mL). Compared to men with low 25(OH)D serum level (< 20 ng/mL), vitamin D replete men (30–39.9 ng/mL) had significantly lower risk of very low NKA (OR: 0.358; 95% CI: 0.138, 0.929; P = 0.035). In women, both low exercise (OR: 0.529; 95% CI: 0.299, 0.939; P = 0.030) and medium to high exercise (OR: 0.522; 95% CI: 0.277, 0.981; P = 0.043) decreased the risk compared to lack of physical exercise. Interestingly, in men and women older than 60 years, physical exercise significantly decreased the risk. Older-age was associated with increased risk of very low NKA in men, but not in women.ConclusionPhysical exercise and vitamin D were associated with NKA in a gender- and age-dependent manner. Age was a major risk factor of very low NKA in men but not in women

Preliminary Acceptability of a Home-Based Peripheral Blood Collection Device for Viral Load Testing in the Context of Analytical Treatment Interruptions in HIV Cure Trials: Results from a Nationwide Survey in the United States

Frequent viral load testing is necessary during analytical treatment interruptions (ATIs) in HIV cure-directed clinical trials, though such may be burdensome and inconvenient to trial participants. We implemented a national, cross-sectional survey in the United States to examine the acceptability of a novel home-based peripheral blood collection device for HIV viral load testing. Between June and August 2021, we distributed an online survey to people with HIV (PWH) and community members, biomedical HIV cure researchers and HIV care providers. We performed descriptive analyses to summarize the results. We received 73 survey responses, with 51 from community members, 12 from biomedical HIV cure researchers and 10 from HIV care providers. Of those, 51 (70%) were cisgender men and 50 (68%) reported living with HIV. Most (>80% overall) indicated that the device would be helpful during ATI trials and they would feel comfortable using it themselves or recommending it to their patients/participants. Of the 50 PWH, 42 (84%) indicated they would use the device if they were participating in an ATI trial and 27 (54%) also expressed a willingness to use the device outside of HIV cure studies. Increasing sensitivity of viral load tests and pluri-potency of the device (CD4 count, chemistries) would augment acceptability. Survey findings provide evidence that viral load home testing would be an important adjunct to ongoing HIV cure-directed trials involving ATIs. Survey findings may help inform successful implementation and uptake of the device in the context of personalized HIV care

Golf Swing Segmentation from a Single IMU Using Machine Learning

Golf swing segmentation with inertial measurement units (IMUs) is an essential process for swing analysis using wearables. However, no attempt has been made to apply machine learning models to estimate and divide golf swing phases. In this study, we proposed and verified two methods using machine learning models to segment the full golf swing into five major phases, including before and after the swing, from every single IMU attached to a body part. Proposed bidirectional long short-term memory-based and convolutional neural network-based methods rely on characteristics that automatically learn time-series features, including sequential body motion during a golf swing. Nine professional and eleven skilled male golfers participated in the experiment to collect swing data for training and verifying the methods. We verified the proposed methods using leave-one-out cross-validation. The results revealed average segmentation errors of 5–92 ms from each IMU attached to the head, wrist, and waist, accurate compared to the heuristic method in this study. In addition, both proposed methods could segment all the swing phases using only the acceleration data, bringing advantage in terms of power consumption. This implies that swing-segmentation methods using machine learning could be applied to various motion-analysis environments by dividing motion phases with less restriction on IMU placement

SnS44– Metal Chalcogenide Ligand, S2– Metal Free Ligand, and Organic Surface Ligand Toward Efficient CdSe Quantum Dot- Sensitized Solar Cells

Inorganic surface ligands such as metal chalcogenides ligand SnS44- and metal free ligand S2- were introduced for CdSe quantum dot sensitized solar cell (QDSSC) applications. The SnS44- ligand QDs were successfully deposited onto TiO2 photoanode through metal ion coordination. In solution, metal-ammonia complexes of Zn2+, Cd2+, and Cu2+ can be coordinated by the SnS44- ligands and reverse the zeta potential. Similarly, the metal ions can be sandwiched by SnS44- ligands and the photoanode. Using the metal ion bridged SnS44- ligand QDs as the sensitizer, photovoltaic properties of the QDSSCs have been studied. Cd2+ mediated deposition case showed better photovoltaic performance than the cases of Zn2+ or Cu2+. To further investigate the surface ligand effect on QDSSC, organic/inorganic mixed surface CdSe QDs were introduced using partial ligand exchange after the deposition onto the TiO2 photoanode. The postdeposition surface ligand exchange with inorganic ligands such as SnS44- and S2- is thought to retain the initial organic ligands between QDs and TiO2 photoanode and selectively replace the QD ligands that would contact the electrolytes. Metal free S2- ligand QDSSC showed the best photovoltaic performance recording 1.4 times enhanced photocurrent and 1.5 times enhanced photoconversion efficiency when compared with the initial organic surface ligand QDSSC. Comparison studies on the photovoltaic properties of QDSSCs with different surfaces suggest that (i) the Cd-SnS44- complex and SnS44- surface ligand act as efficient electron traps hurdling the photovoltaic performance severely, (ii) S2- surface ligand works as an efficient hole trap only at the interface between the QD and TiO2, and (iii) S2- surface ligand blocks back electron transfers better than the initial organic ligand.X1186sciescopu

Layer-by-Layer Quantum Dot Assemblies for the Enhanced Energy Transfers and Their Applications toward Efficient Solar Cells

Two different quantum dots (QDs) with an identical optical band gap were prepared: one without the inorganic shell and short surface ligands (BQD) and the other with thick inorganic shells and long surface ligands (OQD). They were surface-derivatized to be positively or negatively charged and were used for layer-by-layer assemblies on TiO2. By sandwiching BQD between OQD and TiO2, OQD photoluminescence showed seven times faster decay, which is attributed to the combined effect of the efficient energy transfer from OQD to BQD with the FRET efficiency of 86% and fast electron transfer from BQD to TiO2 with the rate of 1.2 x 10(9) s(-1). The QD bilayer configuration was further applied to solar cells, and showed 3.6 times larger photocurrent and 3.8 times larger photoconversion efficiency than those of the device with the OQD being sandwiched by BQD and TiO2. This showcases the importance of sophisticated control of QD layer assembly for the design of efficient QD solar cells.X112221sciescopu

Gastro-Protective Effect of Fermented Soybean (Glycine max (L.) Merr.) in a Rat Model of Ethanol/HCl-Induced Gastric Injury

The present research purposed to examine the gastro-protective effect of Glycine max (L.) Merr. fermented using Lactobacillus delbrueckii ssp. delbrueckii Rosell-187 (Gastro-AD®) on ethanol/HCl-induced gastric damage, specifically on gastric acid secretion. After oral supplementation of Gastro-AD® to Sprague–Dawley (SD) rats with ethanol/HCl-induced gastric damage, we determined that Gastro-AD® attenuated the gastric mucosal lesion, hemorrhage and gastric acid secretion induced by ethanol/HCl. In addition, we observed that the Gastro-AD® treatment increased the serum prostaglandin E2 level and decreased the levels of gastric acid secretion-related receptors in both gastric tissues and primary gastric parietal cells. Furthermore, it decreased the levels of inflammatory factors, including serum histamine and expression of p-IκB, p-p65, iNOS and COX-2 and the activity of apoptotic signaling pathways, including those involving p-JNK, Bcl2/Bax, Fas, FADD, caspase-8 and caspase-3, in the stomach of the ethanol/HCl-treated rats. Thus, we suggest that Gastro-AD® supplementation may reduce ethanol/HCl-induced gastric acid secretion and prevent gastric injury