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59 result(s) for "Park, Kayoung"
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The association between food benefit online ordering and redemptions: evidence from the Special Supplemental Nutrition Program for Women, Infants, and Children
Objective:To examine how the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) online food benefit ordering could influence WIC benefit redemptions.Design:A cross-sectional study. We compare the average redemption rates between online ordering early adopters and non-adopters among WIC customers before and after implementing WIC online ordering. A propensity score-weighted difference-in-difference model was used to estimate the coefficients.Setting:The Oklahoma WIC programme and a grocery store chain in Oklahoma.Participants:12743 Oklahoma WIC households that had redeemed their food benefits at the grocery store chain in 2020.Results:WIC online ordering significantly positively affected redemption rates for eight of the fifteen food categories. For example, the difference-in-difference coefficients (P–values) of these food categories were cheese or tofu (0·077, <0·01), yogurt (0·092, <0·01), whole milk (0·082, 0·022), low-fat milk (0·060, <0·01), eggs (0·049, 0·033), breakfast cereal (0·085, <0·01) and infant formula (0·073, 0·039). Two food categories with significantly negative difference-in-difference coefficients had relatively lower redemption rates overall: canned fish (Coefficient = –0·209, P < 0·01) and infant cereal (Coefficient = –0·138, P = 0·015). There were no significant changes in the redemption of fruits and vegetables (Coefficient = 0·031, P = 0·121).Conclusion:Adopting WIC online ordering was positively associated with benefit redemption rates among most food benefit categories. Our findings provide preliminary but important evidence regarding online food benefit redemption among low-income consumers.
Sustainability in Higher Education: Perceptions of Social Responsibility among University Students
Many construction-related training and education programs in the United States have now embraced the concept of sustainability, offering sustainable construction courses that highlight sustainable design and construction practices. These courses have mainly focused on green building strategies for the design and construction of built environments and indoor environmental quality necessary for students’ knowledge enhancement and career development. This study examined the effect of sustainability course on students’ knowledge as well as their perceptions of social responsibility and sustainable behaviors. Data were collected by conducting a survey from construction related programs in U.S. universities. Students were categorized based on their experience of taking such course(s), and results were compared in terms of their environmental concerns, objective and subjective knowledge, and sustainable consumer behaviors by conducting independent two-sample t-tests. The purpose of this study was to examine sustainable behaviors and social responsibility perceptions among U.S. university students enrolled in construction-related courses. The results indicated that environmental concern and sustainable consumer behavior scores were significantly lower among students who had taken the course than those who had not. Both objective and subjective knowledge scores were relatively low. There was no difference between the two groups in objective knowledge scores and unexpectedly, subjective knowledge was significantly lower among students who had taken the course than those who had not. The findings of this study provide implications for sustainability curriculum development that can enhance students’ learning experience.
Effect of Double-Sided 3D Patterned Cathode Catalyst Layers on Polymer Electrolyte Fuel Cell Performance
Optimization of the structure of cathode catalyst layers (CCLs) for promoting the transfer of reactants and products in polymer electrolyte fuel cells (PEFCs) is important for improving the cell performance. In this study, using theoretical equations, we confirmed that the shortened proton conduction path in the ionomer layer (IL) with a 3D-patterned structure, compared to that in the IL with a flat-patterned structure, can improve the cell performance. We experimentally investigated the effect of the IL with a 3D-patterned structure included in the CCLs on the cell performance. Based on the combination of the flat- or 3D-pattern of the IL and the catalyst layer (CL), the samples were categorized as Str. 1 (3D-patterned CL without IL), Str. 2 (flat-patterned IL and CL), Str. 3 (3D-patterned IL and flat-patterned CL), and Str. 4 (3D-patterned IL and CL). All of the samples had different morphologies. According to the I–V curves and impedance spectra data acquired at 80 °C and 40% relative humidity, Str. 4 showed superior cell performance relative to those of the other CCLs. These results indicate that the structure of Str. 4 enhanced the proton conductivity at a low humidity at which proton conduction is usually poor, thereby resulting in improved cell performance.
Numerical analysis on influence of surface structures of cathode catalyst layers on performance of polymer electrolyte fuel cells
Because it is time‐consuming to optimize the design of a cathode catalyst layer (CCL), a numerical simulation to predict the reaction and mass transport characteristics without trial and error is desirable. This study used numerical analysis to investigate how the mass transport occurring in CCLs with flat and three‐dimensional (3D) structures influenced the performance. The simulations included the reconstruction of the CCLs and their electrochemical calculation using our multi‐block model. The simulation results showed the reduction of the proton resistance in the ionomer was a factor in improving the performance in the 3D structure in comparison with the flat structure. An increasing aspect ratio of the 3D structure improved the cell performance and decreased the proton resistance in the ionomer. These results were due to the shortened conductive path of the protons from the polymer electrolyte membrane to the gas diffusion layer side surface in the 3D structure. Finally, the cell performance with an increase in the ionomer content was predicted. This numerical analysis made it possible to understand the reaction of the 3D structure and mass transport and predict ways to optimize the structural design to improve cell performance.
Impact of a delirium prevention project among older hospitalized patients who underwent orthopedic surgery: a retrospective cohort study
Background Postoperative delirium (POD) is a common clinical syndrome with significant negative outcomes. Thus, we aimed to evaluate the feasibility and effectiveness of a delirium screening tool and multidisciplinary delirium prevention project. Methods A retrospective cohort study was conducted at a single teaching center in Korea. A cohort of patients who underwent a delirium prevention program using a simple delirium screening tool from December 2018 to February 2019 (intervention group, N  = 275) was compared with the cohort from the year before implementation of the delirium prevention program (December 2017 to February 2018) (control group, N  = 274). Patients aged ≥65 years who were admitted to orthopedic wards and underwent surgery were included. The incidence rates of delirium before and after implementation of the delirium prevention program, effectiveness of the delirium screening tool, change in the knowledge score of nurses, and length of hospital stay were assessed. Results The sensitivity and specificity of the screening tool for the incidence of POD were 94.1 and 72.7%, respectively. The incidence rates of POD were 10.2% (control group) and 6.2% (intervention group). The odds ratio for the risk reduction effect of the project related to the incidence of POD was 0.316 (95% confidence interval: 0.125–0.800, p  = 0.015) after adjustment for possible confounders. The delirium knowledge test score increased from 40.52 to 43.24 out of 49 total points ( p  < 0.001). The median length of hospital stay in the intervention and control groups was 6.0 (interquartile range, 4–9) and 7.0 (interquartile range, 4–10) days, respectively ( p  = 0.062). Conclusion The screening tool successfully identified patients at a high risk of POD at admission. The POD prevention project was feasible to implement, effective in preventing delirium, and improved knowledge regarding delirium among the medical staff. Trial registration None.
Evaluation of the treatment time-lag effect for survival data
Medical treatments often take a period of time to reveal their impact on subjects, which is the so-called time-lag effect in the literature. In the survival data analysis literature, most existing methods compare two treatments in the entire study period. In cases when there is a substantial time-lag effect, these methods would not be effective in detecting the difference between the two treatments, because the similarity between the treatments during the time-lag period would diminish their effectiveness. In this paper, we develop a novel modeling approach for estimating the time-lag period and for comparing the two treatments properly after the time-lag effect is accommodated. Theoretical arguments and numerical examples show that it is effective in practice.
Two-particle correlation via Bremsstrahlung
Ridge is the well-known structure in two-particle angular correlations at highenergy heavy-ion collisions. This structure is physically understood through elliptic and higher-order flows at nucleus-nucleus collisions. This behavior is also found in small systems, such as proton-proton collisions, recently. However, Ridge structure in small system is hard to be understood using hydrodynamics, since small systems are not dense enough to produce the Quark-Gluon plasma. Thus, we try to describe this phenomena through kinematic interaction between jets and medium partons. In high-energy heavy-ion collision, the energetic particles called jets go out in specific direction and lose their energy while passing through the medium. During such process, photons/gluons are emitted from interaction between jets and medium partons. We concentrate on energy loss via photon radiations, known as Bremsstrahlung. Recently, two symmetric double scattering processes between jet particle and medium parton are reported to be able to produce certain constructive interference, which gives collective motion and medium partons are aligned along incoming jet particles. We conjecture that similar behavior might happen in Bremsstrahlung processes, and therefore we consider the two symmetric diagrams of photon emission and medium parton scattering. We expect these two amplitudes to give constructive interference leading to the collective motion of medium. We check the correlation between emitted photon and final jet, and those between medium parton and final jet for high-energy jet. To describe parton momentum distribution in medium, we use the Maxwell-Boltzmann distribution. We discover collective motion in both angular correlations. We also check the tendency of the angular correlation for two particles according to the incident angle of jet particle, energy of emitted photon and temperature of systems, respectively. We can conclude that collective motion is able to be understood through kinematic description.
The Online Ordering Behaviors among Participants in the Oklahoma Women, Infants, and Children Program: A Cross-Sectional Analysis
The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) is a nutrition assistance program in the United States (U.S.). Participants in the program redeem their prescribed food benefits in WIC-authorized grocery stores. Online ordering is an innovative method being pilot-tested in some stores to facilitate WIC participants’ food benefit redemption, which has become especially important in the COVID-19 pandemic. The present research aimed to examine the online ordering (OO) behaviors among 726 WIC households who adopted WIC OO in a grocery chain, XYZ (anonymous) store, in Oklahoma (OK). These households represented approximately 5% of WIC households who redeemed WIC benefits in XYZ stores during the study period, which was 1 July to 31 December 2020. This period was during the COVID-19 pandemic but after the temporary lockdown in Oklahoma had been lifted. Descriptive statistics were estimated for WIC OO households’ adoption behaviors and their orders. The Cox proportional hazard model and zero-truncated negative binomial regression were applied to examine the relationship between participants’ socio-demographics and the length of time between 1 July 2020, and their first OO, as well as the number of WIC online orders. About 80% of these online orders were picked up without any changes. Minority households had a significantly longer time before adopting their first OO (hazard ratio (HR) < 1, p < 0.001), while households with a child or a woman participant, or more participants, had a shorter time before adopting OO (HR > 1, p < 0.05). Non-Hispanic black households had a fewer number of OOs than non-Hispanic white households (B = −0.374, p = 0.007). OO adoption varied across socio-demographics. More efforts are needed to ensure equal access and adoption of WIC OO.
Evaluation of WIC Online Ordering during the COVID-19 Pandemic: Evidence from an Oklahoma Grocery Store Chain
The COVID-19 pandemic is worsening the disparities in food access in the United States. As consumers have been increasingly using grocery online ordering services to limit their exposure to the COVID-19 virus, participants of federal nutrition assistance programs lack the online benefit redemption option. With the support of the US Department of Agriculture (USDA), retailers are pilot-testing online food benefit ordering in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). By combining the Oklahoma WIC administrative data, the online ordering data from a grocery store chain in Oklahoma, and the COVID-19 data in Oklahoma, this study examines how WIC participants responded to the online food benefit ordering option and how their adoption of online ordering was associated with the COVID-19 incidence. Results show that from July to December 2020, 15,171 WIC households redeemed WIC benefits at an Oklahoma chain store, but only 819 of them adopted online ordering. They together completed 102,227 online orders, which accounted for 2.7% of the store visits and 2.6% of the monetary value of WIC redemptions at these stores. There was no significant relationship between WIC online ordering adoption and COVID-19 incidence in Oklahoma.
Vulnerable Factors Affecting Urinary N-Methylformamide Concentration among Migrant Workers in Manufacturing Industries in Comparison with Native Workers in the Republic of Korea (2012–2019)
Background: Occupational studies on N-N-dimethylformamide (DMF) exposure among migrant workers in Korea are scarce. We determined the urine concentration of N-methylformamide (NMF) among migrant workers with DMF exposure and compared the data with those of native workers. Methods: Data were collected from Workers’ Special Health Examination and Work Environment Monitoring databases during 2014–2019. Workers aged ≥20 years were eligible to participate in the special health examination for DMF exposure. Urine concentrations of NMF were determined and compared between migrant and native workers. We also evaluated the factors affecting the difference in the urine concentration of NMF between the migrant and native workers. Multiple logistic regression was performed by adding confounders step by step. Results: Among 9259 subjects, 504 (5.2%) were migrant workers. The mean urinary concentration of NMF was 6.73 mg/L in migrant workers, which was significantly higher than that in native workers (2.06 mg/L, p < 0.001). The odds of a urine concentration of NMF > 30 mg/L were significantly higher in migrant workers than in native workers after adjusting for sex and age (odds ratio [OR] = 7.31, 95% confidence interval [CI] = 4.66–11.45). However, the odds between the native and migrant workers were not significantly different when fully adjusted for confounders (OR = 1.12, 95% CI = 0.65–1.94). Conclusions: The excessive exposure to DMF among migrant workers was attributed not to differences in biological characteristics but to their work environment. Workers must have awareness of the use of protective equipment and knowledge of hazardous chemicals that they may be exposed to, especially at the workplace.