• Journal of Preventive Medicine and Public Health
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• v.57 no.2
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• pp.108-119
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• 2024

Objectives: Abrupt changes in air pollution levels associated with the coronavirus disease 2019 (COVID-19) outbreak present a unique opportunity to evaluate the effects of air pollution on influenza risk, at a time when emission sources were less active and personal hygiene practices were more rigorous. Methods: This time-series study examined the relationship between influenza cases (n=22 874) and air pollutant concentrations from 2018 to 2021, comparing the timeframes before and during the COVID-19 pandemic in and around Thailand's Khon Kaen province. Poisson generalized additive modeling was employed to estimate the relative risk of hospitalization for influenza associated with air pollutant levels. Results: Before the COVID-19 outbreak, both the average daily number of influenza hospitalizations and particulate matter with an aerodynamic diameter of 2.5 ㎛ or less (PM_2.5) concentration exceeded those later observed during the pandemic (p<0.001). In single-pollutant models, a 10 ㎍/m³ increase in PM_2.5 before COVID-19 was significantly associated with increased influenza risk upon exposure to cumulative-day lags, specifically lags 0-5 and 0-6 (p<0.01). After adjustment for co-pollutants, PM_2.5 demonstrated the strongest effects at lags 0 and 4, with elevated risk found across all cumulative-day lags (0-1, 0-2, 0-3, 0-4, 0-5, and 0-6) and significantly greater risk in the winter and summer at lag 0-5 (p<0.01). However, the PM_2.5 level was not significantly associated with influenza risk during the COVID-19 outbreak. Conclusions: Lockdown measures implemented during the COVID-19 pandemic could mitigate the risk of PM_2.5-induced influenza. Effective regulatory actions in the context of COVID-19 may decrease PM_2.5 emissions and improve hygiene practices, thereby reducing influenza hospitalizations.

• Journal of Gastric Cancer
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• v.12 no.2
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• pp.88-98
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• 2012

Purpose: Local recurrence, due to residual tumor, may occur after endoscopic resection for early gastric cancer. The aims of this study are to evaluate the predictive factors for local recurrence, and suggest an appropriate follow-up biopsy strategy. Materials and Methods: We retrospectively reviewed 396 early gastric cancers from 372 consecutive patients, who underwent endoscopic resection between January 2002 and April 2008. Cumulative recurrence rates were determined by the Kaplan-Meier method, and Cox proportional hazard analysis was used to determine the risk factors for local recurrence. Results: Local recurrence at the endoscopic resection site was found in 17 cases, among the total 396 lesions, during a median follow-up period of 48 months. The 5-year cumulative local recurrence rate was 4.8%. Multivariate analyses determined that tumor involvement at the lateral resection margin [hazard ratio: 35.9; P<0.001], uncheckable lateral resection margin [hazard ratio: 16.8; P<0.001], uncheckable or involved deep resection margin [hazard ratio: 3.76; P=0.047], and piecemeal resection [hazard ratio: 3.95; P=0.007] were associated with local recurrence. If a lesion was positive for any of these risk factors, the 5-year cumulative recurrence rate was 27.0%, while local recurrence was not found in any lesion that lacked these risk factors. Most episodes of recurrence were found during the first or second follow-up endoscopic biopsy at the ulcer scar. Conclusions: Routine follow-up biopsies at the endoscopic resection site might be unnecessary in cases where an early gastric cancer lesion was endoscopically resected en bloc with tumor-free lateral and deep margins.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.615-626
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• 2020

The purpose of this study is to analyze the determinants of risk factor model for the Jordanian banking stocks from 2006 to 2018. This study employs the Five-factor Fama and French's (2015) methodology and uses the annual returns of all Jordanian banks including 2 Islamic and 13 commercial banks listed on the Amman Stock Exchange (ASE) over a period of 13 years. The results show that the factors of value and profitability have an important role in evaluating the expected return in Jordanian banking stocks. Moreover, the value HML and profitability RMW factors provide the highest cumulative returns among these five factors, while the investment CMA and size SMB factors are still around zero cumulative returns. For the market factor, it provides the least negative cumulative returns. The results showed that the largest correlation is between value and investment factors which means that banks with a high book to market value become banks with a conservative investment strategy. The result of the sub-periods confirmed the value and profitability results. The findings of this study suggest that the five-factor Fama and French model is the choice of building an investment portfolio, especially the factors of value and profitability.

• East Asian mathematical journal
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• v.37 no.1
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• pp.79-85
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• 2021

In this paper, we investigate the valuation of vulnerable exchange option that has credit risk of option issuer. The reduced-form model is used to model credit risk. We assume that credit event is determined by the jump of the counting process with stochastic intensity, which follows the mean reverting process. We propose a simple approach to derive the closed-form pricing formula of vulnerable exchange option under the reduced-form model and provide the pricing formula as the standard normal cumulative function.

• Tuberculosis and Respiratory Diseases
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• v.82 no.4
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• pp.341-347
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• 2019

Background: Information about the epidemiology of venous thromboembolism (VTE) recurrence in Korea is lacking. The purpose of this study was to investigate VTE cumulative recurrence rates and identify risk factors for VTE recurrence among Korean adults. Methods: A retrospective cohort study was conducted on adult patients (${\geq}18years$) admitted to a university teaching hospital for pulmonary embolism (PE) from 2005 to 2013. The main outcome of interest was a recurrence of VTE. We used Cox proportional hazard regression analyses to calculate the relative risk of VTE recurrence. Results: Five-year cumulative incidence of recurrent VTE events was 21.5% (95% confidence interval [CI], 17.7-25.4) in all cases of PE; 17% after provoked and 27% after unprovoked PE. Multivariate analysis showed that body mass index (BMI) of ${\geq}25$ (hazard ratio [HR], 2.02; 95% CI, 1.17-3.46; p=0.01) and longer anticoagulation therapy duration (HR, 0.90; 95% CI, 0.84-0.96; p<0.01) were independently associated with risk of VTE recurrence. Risk factors not found to be statistically significant at the <0.05 level included history of VTE (HR, 1.81; 95% CI, 0.84-3.88; p=0.12), unprovoked PE (HR, 1.70; 95% CI, 0.89-3.25; p=0.10), symptomatic deep vein thrombosis (HR, 1.62; 95% CI, 0.89-2.94; p=0.10), and female sex (HR, 1.42; 95% CI, 0.78-2.55; p=0.24). We found that age, history of cancer, and other co-morbidities did not significantly affect the risk of VTE recurrence. Conclusion: Recurrence of VTE after PE is high. Patients with BMI ${\geq}25$ or reduced anticoagulation therapy duration have a higher risk of recurrent VTE.

• 대한예방의학회:학술대회논문집
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• 1994.02a
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• pp.651-657
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• 1994

To assess quantitatively the association between benzene exposure and leukemia, we examined the mortality rate of a cohort with occupational exposure to benzene. Cumulative exposure for each cohort member was estimated from historical air-sampling data and, when no sampling data existed, from interpolation on the basis of existing data. The overall standardized mortality ratio (a measure of relative risk multiplied by 100) for leukemia was 337 (95 percent confidence interval, 154 to 641), and that for multiple myeloma was 409 (95 percent confidence interval, 110 to 1047). With stratification according to levels of cumulative exposure, the standardized mortality ratios for leukemia increased from 109 to 322, 1186, and 6637 with increases in cumulative benzene exposure from less than 40 parts per million-years (ppm-years), to 40 to 199, 200 to 399, and 400 or more. respectively. A cumulative benzene exposure of 400 ppm years is equivalent to a mean annual exposure of 10 ppm over a 40-year working lifetime; 10 ppm is the currently enforceable standard in the United States for occupational exposure to benzene. To examine the shape of the exposure-response relation, we performed a conditional logistic-regression analysis, in which 10 controls were matched to each cohort member with leukemia. From this model, it can be calculated that protection from benzene induced leukemia would increase exponentially with any reduction in the permissible exposure limit.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2473-2476
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• 2012

Background: In papillary and follicular thyroid cancers (PTC, FTC), nodal and distant metastasis are generally considered important determinants of recurrence and survival, respectively. However, there is no consensus about the threshold primary tumour size (PTS) for these determinants. The aim of this study was to assess size relationships for developing nodal, pulmonary, bone and overall distant metastases. Methods: This prospective study covered 139 (93 females and 46 males) consecutive biopsy proven patients with PTC (114/139, mean age $41.0{\pm}15.7$ years, M: F, 35%:65%) and FTC (25/139, mean age $39.2{\pm}14.3$ years, M: F: 24%:76%). Results: Average primary tumor size was $23.4{\pm}11.1$ mm and $26.5{\pm}13.1$ mm for PTC and FTC respectively (p value=0.223). Nodal metastasis was found more common in PTC than FTC (49% vs 28%, p value <0.05), whereas overall distant metastasis was approximately the same (13% and 24%, p value=0.277); however, bone metastasis was significantly higher in FTC than PTC (24% vs 5%, p value <0.05). Cumulative risk for nodal and distant metastases for FTC and PTC starts at PTS <20 mm and may indicate an unusual aggressive tumor behavior in the studied population. Highest cumulative risk for nodal and pulmonary metastases in PTC and for bone metastasis in FTC was found to be ${\geq}50$ mm PTS. Conclusion: We conclude that a PTS of <20 mm may indicate an unusual aggressive tumor behavior with highest cumulative risk for nodal and pulmonary metastases in PTC and for bone metastasis in FTC with a cutoff of ${\geq}50$ mm.

• Safety and Health at Work
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• v.8 no.2
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• pp.130-142
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• 2017

Background: Osteoarthritis of the knee is considered to be related to knee straining activities at work. The objective of this review is to assess the exposure dose-response relation between kneeling or squatting, lifting, and climbing stairs at work, and knee osteoarthritis. Methods: We included cohort and case-control studies. For each study that reported enough data, we calculated the odds ratio (OR) per 5,000 hours of cumulative kneeling and per 100,000 kg of cumulative lifting. We pooled these incremental ORs in a random effects meta-analysis. Results: We included 15 studies (2 cohort and 13 case-control studies) of which nine assessed risks in more than two exposure categories. We considered all but one study at high risk of bias. The incremental OR per 5,000 hours of kneeling was 1.26 (95% confidence interval 1.17-1.35, 5 studies, moderate quality evidence) for a log-linear exposure dose-response model. For lifting, there was no exposure dose-response per 100,000 kg of lifetime lifting (OR 1.00, 95% confidence interval 1.00-1.01). For climbing, an exposure dose-response could not be calculated. Conclusion: There is moderate quality evidence that longer cumulative exposure to kneeling or squatting at work leads to a higher risk of osteoarthritis of the knee. For other exposure, there was no exposure dose-response or there were insufficient data to establish this. More reliable exposure measurements would increase the quality of the evidence.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.14
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• pp.5675-5679
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• 2015

Background: Low-risk human papillomavirus (LR-HPV) infection is the main cause of genital warts. LRHPV genotypes 6 and 11 are associated with genital warts, but there have only been a few published studies about the genotype-specific prevalence of HPV in genital warts in China. The objective of our study was to assess the prevalence of HPV genotypes for clinical cases involving both men and women and to evaluate the potential benefit of a quadrivalent (genotypes 6, 11, 16, and 18) HPV vaccine in eastern Guangdong province of China. Materials and Methods: A total of 696 eligible patients with genital warts were enrolled during the period Aug 2009 through Oct 2014. Specimens were collected from genital warts, the HPV GenoArray test was used for HPV detection and genotyping, which could detect 21 HPV genotypes, including genotypes 6, 11, 16, and 18. Results: Among the 696 cases, 675 samples were successfully genotyped. The median age of patients was 32.1 years (range, 16-67 years). The most prevalent genotypes were HPV-6 (285/675, 42.2%), HPV-11 (265/675, 39.3%), HPV-52 (52/675, 7.7%), HPV-16 (51/675, 7.56%), HPV-81 (50/675, 7.40%) and HPV-58 (37/675, 5.48%). Low-risk genotypes predominated, with a prevalence of 96.59%. The cumulative prevalence of genotypes 6 and 11 was 78.7% (531/675), the cumulative prevalence of genotypes 16 and 18 was 11.6% (78/675), and the cumulative prevalence of genotypes 6, 11, 16, and 18 was 82.5% (557/675). Conclusions: Our results provide strong evidence that, in eastern Guangdong, different from Western countries, the most prevalent low risk HPV genotypes in patients with genital warts are 6, 11 and 81. The quadrivalent HPV vaccine could prevent 82.5% of genital warts in eastern Guangdong.

• Korean Journal of Ecology and Environment
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• v.56 no.4
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• pp.406-413
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• 2023

Captive breeding and reintroduction are crucial strategies for conserving endangered species populations. However, fish raised in predator-free environments, show a lack of recognition of predationrelated stimuli such as chemical and visual signals. It is critical to recognize chemical signals from injured conspecifics, also known as alarm signals, and the order or shape of predators to indicate the spread of predation risk in the habitat. We conducted a laboratory experiment to determine and adjust the optimal exposure period to induce appropriate anti-predator behavior response to different types of stimuli (Chemical, Visual and Chemical+Visual) for the endangered species Microphysogobio rapidus. Our results demonstrate that predator avoidance behavior varies depending on the types of stimuli and the duration of predation risk exposure. First, the results showed captive-breed M. rapidus show lack of response against conspecific alarm signal (Chemical cue) before the predation risk exposure period and tend to increase response over predation risk exposure time. Second, response to predator (visual cue) tend to peak at 48 hours cumulative exposure, but show dramatic decrease after 72 hours cumulative exposure. Finally, response to the mixed cue (Chemical+visual) tend to peak prior to the predation risk exposure period and show reduced response during subsequent exposure periods. This experiment confirms the lack of responsiveness to conspecific alarm signals in captive-bred M. rapidus and the need for an optimal nature behavior enhancement program prior to release of endangered species. Furthermore, responsiveness to predator visual signal peak at 48 hours cumulative exposure, suggest an optimal predation risk exposure period of up to 48 hours.