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Associations of Bisphenol A Exposure With Heart Rate Variability and Blood Pressure
Bae, Sanghyuk,Kim, Jin Hee,Lim, Youn-Hee,Park, Hye Yin,Hong, Yun-Chul Ovid Technologies Wolters Kluwer -American Heart A 2012 Hypertension Vol.60 No.3
<P>Bisphenol A (BPA) is a high-volume production chemical that has been suspected to have adverse health effects. Recent studies have suggested that cardiovascular diseases are associated with the BPA exposure. The aim of present study was to investigate the associations of urinary BPA with heart rate variability and blood pressure. We recruited 560 noninstitutionalized elderly citizens from August 2008 to August 2010 in Seoul. All of the participants were 60 years old. The participants took medical examinations 5 times. Urinary BPA concentration, heart rate variability, and blood pressure were measured at each time. A total of 1511 observations from 521 participants were included in the analyses. We observed that urinary BPA was associated negatively with the root mean square of successive differences for heart rate and positively with blood pressure. The odds ratio of showing hypertension (systolic blood pressure 140 mm Hg or diastolic blood pressure 90 mm Hg) was 1.27 (95% CI, 0.85-1.88) in the fourth quartile compared with the first quartile of urinary BPA concentration. When the analyses were restricted to participants who did not report previous history of hypertension (n=258), the odds ratio was increased to 2.35 (95% CI, 1.33-4.17).</P>
Causal inference in environmental epidemiology
Sanghyuk Bae,Hwan-Cheol Kim,Byeongjin Ye,Won-Jun Choi,Young-Seoub Hong,Mina Ha 환경독성보건학회 2017 환경독성보건학회지 Vol.32 No.-
Inferring causality is necessary to achieve the goal of epidemiology, which is to elucidate the cause of disease. Causal inference is conducted in three steps: evaluation of validity of the study, inference of general causality, and inference of individual causality. To evaluate validity of the study, we propose a checklist that focuses on biases and generalizability. For general causal inference, we recommend utilizing Hill’s 9 viewpoints. Lastly, individual causality can be inferred based on the general causality and evidence of exposure. Additional considerations may be needed for social or legal purposes; however, these additional considerations should be based on the scientific truth elucidated by the causal inference described in the present article.
Epidemiological Characteristics of COVID-19 Outbreak at Fitness Centers in Cheonan, Korea
Bae Sanghyuk,Kim Hwami,Jung Tae-Young,Lim Ji-Ae,Jo Da-Hye,Kang Gi-Seok,Jeong Seung-Hee,Choi Dong-Kwon,Kim Hye-Jin,Cheon Young Hee,Chun Min-kyo,Kim Miyoung,Choi Siwon,Chun Chaemin,Shin Seung Hwan,Kim H 대한의학회 2020 Journal of Korean medical science Vol.35 No.31
Background: In February 2020, a coronavirus disease 2019 (COVID-19) outbreak was reported in fitness centers in Cheonan, Korea. Methods: From February 24 to March 13, an epidemiological investigation was conducted on the fitness center outbreak. All those who were screened were tested for severe acute respiratory syndrome coronavirus-2 (SARS CoV-2) using real-time reverse transcriptase polymerase chain reaction. Contacts were traced and self-isolated for 14 days. We determined the epidemiological characteristics of confirmed cases of SARS-CoV-2 infection, and estimated the time-dependent reproduction number to assess the transmission dynamics of the infection. Results: A total of 116 cases were confirmed, and 1,687 contacts were traced. The source cases were 8 Zumba instructors who led aerobics classes in 10 fitness centers, and had the largest average number of contacts. A total of 57 Zumba class participants, 37 of their family members, and 14 other contacts were confirmed as cases. The attack rate was 7.3%. The contacts at Zumba classes and homes had a higher attack rate than other contacts. The mean serial interval (± standard deviation) were estimated to be 5.2 (± 3.8) days. The time- dependent reproduction number was estimated to be 6.1 at the beginning of the outbreak, but it dropped to less than 1, 2 days after the epidemiological investigation was launched. Conclusion: The results suggest that the COVID-19 outbreak was effectively contained with rigorous contact tracing, isolating, and testing in combination with social distancing without a lock-down.
Sanghyuk An,Byungha Lee,Youngseok Bae,Young-Hyun Lee,Seong-Ho Kim Institute of Electrical and Electronics Engineers 2017 IEEE transactions on plasma science Vol. No.
<P>We present analyses of the transient inductance gradient of an electromagnetic launcher with the sliding contact between rails and armature. When the armature moves along the rails, electrical current concentrates on the contact trailing edge of the armature due to the velocity skin effect, affecting input current spreading into the rail. This effect also induces the temporal variation of inductance gradient. Using the 2-D finite-element method (FEM), the rail inductance gradient without an armature is calculated and compared with the propulsive inductance gradient with a moving armature calculated by 3-D FEM. Using the 3-D simulation, the influence of the step on the height difference between the rail and the transient moving armature is investigated. The result shows that the average of transient inductance gradients during acceleration is 10% larger than Kerrisk's inductance gradient. Also, we found that the axial force on the armature is not significantly affected by the velocity of the armature, while the lateral force on it whose direction is outside the rail increases with the velocity. The circuit simulation using both inductance gradients shows good agreement with the measured current and velocity.</P>