Optical pumping effect in absorption imaging of F=1 atomic gases

We report our study of the optical pumping effect in absorption imaging of $^{23}$Na atoms in the $F=1$ hyperfine spin states. Solving a set of rate equations for the spin populations in the presence of a probe beam, we obtain an analytic expression for the optical signal of the $F=1$ absorption imaging. Furthermore, we verify the result by measuring the absorption spectra of $^{23}$Na Bose-Einstein condensates prepared in various spin states with different probe beam pulse durations. The analytic result can be used in the quantitative analysis of $F=1$ spinor condensate imaging and readily applied to other alkali atoms with $I=3/2$ nuclear spin such as $^{87}$Rb.Comment: 6 pages, 4 figure

Paper Session II-A - Mixed-Mode Interfacial Fracture Toughness of Sandwich Composites at Cryogenic Temperatures

Honeycomb sandwich composites are found in a wide range of structural applications due to their high strength and stiffness-to-weight ratio compared to other systems. Current use of sandwich composites ranges from secondary structures in commercial aircrafts to primary structures in military aircraft, helicopters, and reusable launch vehicles, e.g. Space Shuttle. One of the applications of sandwich construction is in the liquid hydrogen tank of future RL V\u27s. Because of their low density and high stiffness sandwich construction is attractive for LH2 tank. However, past tests shave shown that leakage of hydrogen through the composite face sheet and subsequent de bonding of the face-sheet is a major concern in using sandwich construction. This problem can be eliminated by thorough understanding of the fracture mechanics of face sheets under cryogenic conditions. This study aimed to understand the failure phenomena of sandwich composites constructed from carbon fiber/epoxy composite face sheets and Nomex honeycomb cores. Both experiments including testing ·under cryogenic conditions and finite element analyses are performed to understand the conditions under which debonding occurs and propagates. One of the major objectives of the study is to measure the critical energy release rate or fracture toughness of the face-sheet/core interface, which will be a strong function of mode-mixity and temperature. Furthermore, mode-mixity itself will depend up on the geometric factors such as crack length, face sheet and core thickness, and material stiffness parameters. Fracture tests similar to double cantilever beams will be performed on sandwich panels containing initial delaminations. The fracture toughness will be measured for various crack lengths. The loads at which crack propagation occurs will be applied in the finite element model of the panel to obtain the detailed stress field in the vicinity of the crack tip. From the results of the fracture tests and finite element analysis the interfacial fracture toughness of the sandwich panel under cryogenic conditions can be measured. Application of the results to the design of a LH2 tank will be demonstrated

Demographic and Socioeconomic Influences on Sleep Patterns among Adolescent Students

Although proper sleep is an important topic in adolescent health, little is known about the sleep patterns of adolescents from a longitudinal and non-Western perspective. To fill this gap, the present research conducted a longitudinal study of the impact of demographic and socioeconomic factors on sleep patterns among Korean adolescent students. The relationship could positively or negatively affect sleep. Therefore, it is important to understand which demographic and socioeconomic factors are related to sleep patterns. This study used nationally representative panel data from the Korean Children and Youth Panel Survey. A series of descriptive analyses were conducted to provide overall characteristics of the sample. Furthermore, mixed effect regression analysis techniques were employed to test the relationship between demographic and socioeconomic factors and sleep patterns. Paternal employment status was associated with adolescent sleep patterns, while maternal employment status was not. Adolescents with both parents working compared to adolescents with one parent or none working showed different sleep patterns on weekdays but not on weekends. Both parents possessing college degrees, household income, living in an urban area, and family type were associated with adolescent sleep pattern indicators to varying degrees. Some of these associations varied according to adolescent sex. This study provides insight into the impact of demographic and socioeconomic factors on weekend and weekday sleep patterns among adolescent students by sex. These findings provide information for the promotion of healthy sleep in adolescents by addressing demographic and socioeconomic factors

Relationships between Sleep Patterns, Health Risk Behaviors, and Health Outcomes among School-Based Population of Adolescents:A Panel Analysis of the Korean Children and Youth Panel Survey

Sleep patterns among adolescents are related to health outcomes and health risk behaviors. This study aimed to describe sleep patterns of Korean adolescents and to find the association between sleep patterns and health risk behaviors and health outcomes. Using the junior high school students' panel data (n = 2351, 12-15 years old) from the Korean Children and Youth Panel Survey, this study described the sleep patterns operationalized as rising time, bedtime, and sleep duration both on weekdays and weekends. The relationships of sleep patterns with health outcomes and/or health risk behaviors were tested using mixed effect linear regression for continuous health variables and using mixed effect logit regression for binary health variables. Obesity status, the number of chronic symptoms, self-rated health status, smoking, and alcohol consumption were associated with rising time on weekdays after controlling for gender, living area, and housing type. The same set of variables except for the number of chronic symptoms were associated with bedtime during the weekdays. Sleep duration during the weekdays was associated with obesity status, smoking, and alcohol consumption. Similar patterns of association between sleep pattern variables during the weekends and health-related outcome variables were found, but were less obvious than those for weekdays. Significant relationships between sleep patterns and various health-related variables were found among adolescents in Korea. The results from this study indicate that helping adolescents change their sleeping times as necessary to ensure adequate sleep should be considered important in diminishing health risk behaviors and promoting positive health outcomes

Medical Expenses of North Korean Defectors with Post-Traumatic Stress Disorder

Objective The purpose of this study was to establish the prevalence of PTSD among North Korean defectors who visited the National Medical Center, Seoul, South Korea over a period of approximately 10 years by examining their medical records and to examine differences in the medical service usage patterns of patients with and without PTSD. Methods Data from North Korean defectors who used outpatient services at the National Medical Center during a period of 10 years and 3 months (January 1 2006 to February 28, 2016) were analyzed. The general characteristics of the defectors were analyzed by frequency analyses, and descriptive statistics were generated. Additionally, independent t-tests and chi square analyses were performed to examine differences between PTSD patients and those without PTSD. Linear regression analysis was performed to examine factors affecting the mental health of North Korean defectors suffering from PTSD. Results This study assessed the correlations between PTSD, the average number of outpatient visits, and the total revenue. The regression analysis showed a relationship between PTSD and the average number of outpatient visits. There was also a correlation between PTSD and total revenue. The average number of outpatient visits was 41.8 for PTSD patients, whereas it was 33.2 for those without PTSD. The. total revenue visit was 953.6 USD for PTSD sufferers and 231.1 USD for those without PTSD. Conclusion This study found that the majority of North Korean defectors visit psychiatry departments, and that PTSD patients use outpatient services more frequently and have higher total revenue than those without PTSD. Additionally, patients with PTSD used a greater variety of medical services. Considering the high medical care expenses of North Korean defectors residing in South Korea, future investigations should examine the medical service usage patterns of such patients, especially those diagnosed with PTSD, in greater detail