• Journal of applied mathematics & informatics
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• v.27 no.3_4
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• pp.779-793
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• 2009

This paper deals with a delayed SEIRS epidemic model with pulse vaccination and crowded incidence rate. Moreover, the case of vertical and horizontal transmission is considered. By using the discrete dynamical system determined by the stroboscopic map, the exact infection-free periodic solution of the SEIRS model is obtained. Further, by employing the comparison arguments, we prove that under the condition that $R_*$ < 1 the infection-free periodic solution is globally attractive, and that under the condition that $R^*$ > 1 the disease is uniformly persistent, which means that after some period of time the disease will become endemic.

• Safety and Health at Work
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• v.11 no.2
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• pp.241-243
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• 2020

Coronavirus disease 2019 poses an occupational health risk to health-care workers. Several thousand health-care workers have already been infected, mainly in China. Preventing intra-hospital transmission of the communicable disease is therefore a priority. Based on the Systems Engineering Initiative for Patient Safety model, the strategies and measures to protect health-care workers in an acute tertiary hospital are described along the domains of work task, technologies and tools, work environmental factors, and organizational conditions. The principle of zero occupational infection remains an achievable goal that all health-care systems need to strive for in the face of a potential pandemic.

• Research in Plant Disease
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• v.28 no.1
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• pp.39-45
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• 2022

Patterns of occurrence of tomato yellow leaf curl virus (TYLCV) and tomato chlorosis virus (ToCV) with whitefly on summer-cultivated tomato in Gwangju-si, Gyeonggi Province were surveyed using multiplex reverse transcription-polymerase chain reaction in 2020. In addition, distribution of the whiteflies species and their viral transmission rates were investigated throughout the tomato growing season. The infection rates of TYLCV and ToCV increased sharply during harvest, and the single infection rates were 30.9% and 5.0%, respectively, with a mixed infection rate of the two viruses being the highest at 52.2%. Single infection with TYLCV and double infections with TYLCV and ToCV accounted for the majority with 83.1%. Bemisia tabaci were dominant over Trialeurodes vaporariorum in greenhouse grown plants, and all of the investigated B. tabaci biotypes were identified as Mediterranean (MED, formerly known as Q biotype). The transmission rate of TYLCV, detected in every sampled B. tabaci MED population, was 21.4%, and the mixed transmission rate with ToCV was 35.5%. Viruliferous MED whiteflies with ToCV showed a higher rate than that of T. vaporariorum. In the transplant stage, viruliferous rate of both TYLCV and ToCV of B. tabaci was 42.7%; this rate was highest in the harvest stage. In examination of tomato yield, the increase in the mixed infection rate of TYLCV and ToCV led to complete yield loss. When the mixed infection rate increased by 10%, the yield decreased by 405.4 kg/10a.

• Biomolecules & Therapeutics
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• v.1 no.1
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• pp.98-102
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• 1993

The therapeutic effectiveness of adenine arabinoside(tora-A) and its conjugate of prednisone(BR-8702-AP) was compared in Herpes simplex Virus Type 1 (HSV-1) infected BALB/C mice. The BALB/C mouse was infected with HSV-1(700 PFU/mouse) intranasally. Among mice infected intranasally with virus, a mortality rate of 100% was observed. On the oral administration of non-toxic doses of ara-A or BR-8702-AP(125 mg /kg/day) for 5 consecutive days 2 hours after virus infection, the tora-A was highly effective in reducing mortality to 0% (P<0.001) and BR-8702-AP was also effective in reducing mortality to 15% (P<0.01). In this model infection, the virus was first replicated in the lung and transmitted to the brain. Both arts-A and BR-8702-AP did not inhibit the viral replication in the lung, but they inhibited the viral transmission to the brain. However, the BR-8702-AP was less effective than the aria-A to prevent transmission of virus to brain. Therefore, the reduced mortality due to tora-A or BR-8702-AP therapy was associated with inhibition of viral transmission to brain.

• Nonlinear Functional Analysis and Applications
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• v.29 no.2
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• pp.597-620
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• 2024

In this study, the conformable fractional derivative(CFD) of order 𝝔 in conjunction with the LC operator of orderρ is used to develop the model of the transmission of the A(H1N1) influenza infection. A brand-new A(H1N1) influenza infection model is presented, with a population split into four different compartments. Fixed point theorems were used to prove the existence of the solutions and uniqueness of this model. The basic reproduction number R₀ was determined. The least and most sensitive variables that could alter R₀ were then determined using normalized forward sensitivity indices. Through numerical simulations carried out with the aid of the Adams-Moulton approach, the study also investigated the effects of numerous biological characteristics on the system. The findings demonstrated that if 𝝔 < 1 and ρ < 1 under the CFD, also the findings demonstrated that if 𝝔 = 1 and ρ = 1 under the CFD, the A(H1N1) influenza infection will not vanish.

• Journal of Microbiology and Biotechnology
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• v.27 no.5
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• pp.1005-1009
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• 2017

Primary cytomegalovirus (CMV) infection during pregnancy can cause congenital defects. Available data for CMV infection during pregnancy in north China are inadequate. The aim of this study was to evaluate the epidemiology of maternal CMV infection and explore the incidence of congenital infection. In this prospective study, serum CMV IgG and IgM antibodies were measured in 2,887 pregnant women using ELISA, and the IgG avidity test was performed on all IgM-positive subjects. The seroprevalence of anti-CMV IgG was 94.70%, and of anti-CMV IgM was 1.28%. CMV IgG prevalence increased significantly with age (p < 0.01). Women living in downtown areas showed higher IgG prevalence than those residing in urban areas (p = 0.023). CMV-IgM seroprevalence was highest in autumn (p = 0.021). There was no difference in IgM seroprevalence by age, socioeconomic status, geographical area, or gravida. The rate of primary CMV infection was 0.45% (13/2,887) at the first trimester. The seroconversion rate during pregnancy was 0.76% (22/2,887). One woman underwent seroconversion during pregnancy and gave birth to an infant with asymptomatic CMV infection. Congenital CMV infection was diagnosed in five of the 14 infants from 14 mothers with active infection, for a vertical transmission rate of 35.71% (5/14). Three infants were asymptomatic, whereas two infants presented symptomatic infection with hearing deficits. Although CMV IgG prevalence is relatively high in north China, significant attention to primary CMV infection during pregnancy is still needed.

• Journal of Veterinary Science
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• v.24 no.2
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• pp.21.1-21.5
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• 2023

Under the current African swine fever (ASF) epidemic situation, a science-based ASF-control strategy is required. An ASF transmission mechanistic model can be used to understand the disease transmission dynamics among susceptible epidemiological units and evaluate the effectiveness of an ASF-control strategy by simulating disease spread results with different control options. The force of infection, which is the probability that a susceptible epidemiological unit becomes infected, could be estimated by applying an ASF transmission mechanistic model. The government needs to plan an ASF-control strategy based on an ASF transmission mechanistic model.

• Korean Journal of Veterinary Service
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• v.33 no.2
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• pp.97-103
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• 2010

Foot-and-mouth disease (FMD) commonly infects cloven-hoofed livestock animals such as cattle, pig, sheep, and goat and its clinical signs are well-known. Besides livestock, FMD can be transmitted among cloven-hoofed animals in the wild. FMD mostly affects livestock animals in farms, but, wild animals are likely to play a pivotal role in spreading the disease due to their way of free living. In the case of deer, the clinical signs of FMD vary widely from subclinical to severe infections. Thus, in some deer species, it may be hard to verify clinical signs of FMD. A deer may carry the virus up to 11 weeks after exposure, shedding the virus during the period. However, deer is not considered as a typical host for persistent infection like buffalo, cattle or sheep. In Korea, small-scale livestock farms which have less than 10 animals make up 63.6% of the entire livestock farms. Considering raising environment in deer farms, it is assumed that the risk of virus excretion and consequent transmission of FMD among deers is relatively lower than other cloven-hoofed animals. However, Sika deer and Elk which are typical deer species in Korea would manifest mild to subclinical symptoms upon FMD infection. Therefore, laboratory testing is necessary to confirm FMD in these animals because of difficulty in verifying clinical signs and the risk of virus shedding during inapparent infection.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.19 no.1
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• pp.122-133
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• 2012

Purpose: The purpose of this study was to develop a web-based education program on control vancomycin-resistant enterococci (VRE) infections and to identify the effects of the program on knowledge and performance of nursing students. Methods: The web-based VRE infection control education program was developed by using the network-based instructional systems design model. The nursing students in the experimental group could access this web-based education program at any time, and as many times as they wanted, during the clinical training period. Effects were evaluated by assessing knowledge and performance of VRE infection control measures during the clinical training period. Results: The contents of the education program included diagnosis, transmission, and treatment of VRE, contact precautions, hand washing, personal protective equipment, environment management, and quizzes. The lecture portion was filmed in a virtual screen studio using flash animation, video, and sound effects, and it was uploaded on an internet site. The knowledge and performance scores of the experimental group after using the education program were significantly higher than those of the control group. Conclusion: The results suggest that the web-based VRE infection control education program is an effective educational method to enhance knowledge and performance of VRE infection control measures.

• Journal of Korean Biological Nursing Science
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• v.14 no.1
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• pp.8-15
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• 2012

Purpose: This study was undertaken to identify the knowledge and compliance level of nursing students. It was based on self-administered questionnaires about multidrug-resistant organisms (MDROs). Methods: The test group was 184 nursing students who had contact with MDROs during clinical practice. The study was conducted from May 1 to September 16, 2011. Results: The average knowledge level of MDROs was 16.20 (correct answer rate: 67.5%). The nurses' compliance level of MDROs infection control was on average 40.50 (range: 13-52). "Hand hygiene" ranked highest in the compliance level of MDROs infection control. The lowest level of MDRO infection control was the wearing of disposable aprons or gowns. Conclusion: This study demonstrated the nursing students' knowledge and the compliance level of infection control. We suggest that nursing students receive mandated systematic education of MDROs in the nursing curriculum. And clinical practice experience of MDROs infection control is required in hospitals. These steps will help prevent transmission of MDROs in nursing settings.