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We quantitatively assessed the fit failure rate of N95 respirators according to the number of donning/doffing and hours worn.
A tertiary-care referral center in South Korea.
In total, 10 infection control practitioners participated in the fit test.
The first experiment comprised 4 consecutive 1-hour donnings and fit tests between each donning. The second experiment comprised 2 consecutive 3-hour donnings and fit tests between each donning. The final experiment comprised fit tests after an 1-hour donning or a 2-hour donning.
For 1-hour donnings, 60%, 70%, and 90% of the participants had fit failures after 2, 3, and 4 consecutive donnings, respectively. For 3-hour donnings, 50% had fit failure after the first donning and 70% had failures after 2 consecutive donnings. All participants passed the fit test after refitting whenever fit failure occurred. The final experiment showed that 50% had fit failure after a single use of 1 hour, and 30% had fit failure after a single use of 2 hours.
High fit-failure rates were recorded after repeated donning and extended use of N95 respirators. Caution is needed for reuse (≥1 time) and extended use (≥1 hour) of N95 respirators in high-risk settings such as those involving aerosol-generating procedures. Although adequate refitting may recover the fit factor, the use of clean gloves and strict hand hygiene afterward should be ensured when touching the outer surfaces of N95 respirators for refitting.
Background: Mumps, a contagious disease, is transmissible by respiratory droplet particles and is preventable by vaccination. In South Korea, mandatory vaccination against mumps has markedly reduced its incidence. However, both the incidence and the number of reported cases of mumps have persistently increased in South Korea since 2007. Despite high vaccination rates, mumps outbreaks continue to occur, and many studies have been conducted on mumps seroprevalence in children and adolescents. In comparison, few reports have been published regarding mumps seroprevalence in healthcare workers (HCWs) in South Korea. Objective: We investigated the seroprevalence of HCWs in South Korea. Methods: This study was conducted at Asan Medical Center, a 2,705-bed tertiary-care hospital in Seoul, South Korea, with 8,329 HCWs. In 2018, we performed mumps antibody testing for HCWs. We administered MMR vaccination to all HCWs whose antibody test yielded equivocal or negative results. However, we did not repeat mumps antibody testing after MMR vaccination. Results: In total, 6,055 HCWs (73%) underwent mumps antibody testing. The overall mumps seropositivity rate was 87% (95% CI, 86%–87%). Seropositivity rates of all birth cohorts ranged from 72% to 92%. Mumps seropositivity rates were 88% in HCWs born before 1970, 87% in those born between 1970 and 1989, and 88% in those born between 1990 and 1995 (P = .59). Mumps seropositivity rates for both women and men HCWs were 87% (3,770 of 4,311 women and 1,517 of 1,744 men); the difference was not statistically significant (P = .62). The overall mumps seropositivity rate was 87%, which was above the herd immunity threshold of 75%–86%. Conclusions: Our results revealed that the overall mumps seropositivity rate in South Korean HCWs was above the herd immunity threshold. On the basis of this finding, we recommend that MMR vaccination after serologic testing may be a more reasonable approach than universal MMR vaccination alone in Korea.
Background: Measles is a highly contagious disease that is transmissible by airborne particles but is preventable by vaccination. South Korea has maintained a highly immunized adult population; however, small local outbreaks of measles continued to occur, and there have been some reports of pockets of underimmunity among the young adult population. It is important to know the seroepidemiology of healthcare workers (HCWs) for policy-making process, but data on the seroprevalence of measles in HCWs in South Korea are limited. Methods: We investigated the seroprevalence of HCWs at Asan Medical Center, a 2,705-bed tertiary-care hospital in Seoul, South Korea, with 8,329 HCWs. In 2014, after an outbreak of measles occurred in a university in Seoul, Asan Medical Center required measles IgG tests for all HCWs born in and after 1967 for point-prevalence surveillance. In addition, we have routinely performed measles antibody test for new HCWs since 2014. In 2018, antibody tests were administered to HCWs who were born before 1967 or who had taken a leave of absence in 2014. We provided MMR vaccination to all HCWs whose antibody tests yielded negative results. Results: In total, 7,411 HCWs (89%) underwent measles antibody tests from 2014 to 2018. The overall seropositivity was 73% (95% CI, 72%–74%); seroprevalence was 73% in HCWs born in of after 1967, whereas the seroprevalence in HCWs born before 1967 was 98%. The seroprevalence sharply decreased from 85% in the 1986 birth cohort to 42% in the 1995 birth cohort. Conclusions: In conclusion, the proportion of measles-susceptible individuals was substantially high in HCWs, especially in young adults. Because the impact of measles outbreak in healthcare facilities would be critical, a policy regarding routine serologic screening followed by measles vaccination or routine measles vaccination in healthcare facilities should be considered, especially for young Korean HCWs.
Modern electronics have been geared toward exploring novel electronic materials that can encompass a broad set of unusual functionalities absent in conventional platforms. In this regard, two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductors are highly promising, owing to their large mechanical resilience coupled with superior transport properties and van der Waals (vdW) attraction-enabled relaxed assembly. Moreover, 2D TMD heterolayers based on chemically distinct constituent layers exhibit even more intriguing properties beyond their mono-component counterparts, which can materialize only when they are manufactured on a technologically practical wafer-scale. This mini-review provides a comprehensive overview of recent progress in exploring wafer-scale 2D TMD heterolayers of various kinds. It extensively surveys a variety of manufacturing strategies and discusses their scientific working principles, resulting 2D TMD heterolayers, their material properties, and device applications. Moreover, it offers extended discussion on remaining challenges and future outlooks toward further improving the material quality of 2D TMD heterolayers in both material and manufacturing aspects.
Predicting the isotopic modification of ice by melting processes is important for improving the accuracy in paleoclimate reconstruction. To this end, we present results from cold room laboratory observations of changes in the isotopic ratio (D/H and 18O/16O) of ice cubes by isotopic exchange between liquid water and ice in nearly isothermal conditions. A 1-D model was fit to the isotopic results by adjusting the values of two parameters, the isotopic exchange rate constant (kr) and the fraction of ice participating in the exchange (f). We found that the rate constant for hydrogen isotopic exchange between liquid water and ice may be greater (up to 40%) than that for the oxygen isotopic exchange. The range of the rate constant obtained from four melt experiments is from 0.21 to 0.82 h–1. The model results also suggest that f decreases with the increasing wetness of the ice. This is because with increasing water saturation in ice, water may be present only in the small pores or some of the water that was exchanged with ice may be bypassed, decreasing the effective surface area over which the isotopic exchange can occur. The relationship between the two water isotopes (δ18O vs δD) was observed and modeled and the slope was <8, which is significantly different from the slope of the meteoric waterline. We note that these slopes were obtained without considering the sublimation process.
The aim of the present study was to compare selected obesity indicators with comprehensive health status.
The study employed a pooled cross-sectional design.
BMI, waist circumference, waist-to-height ratio (WHtR) and body fat percentage were considered as indirect obesity indicators. The Edmonton Obesity Staging System (EOSS) was used as a composite indicator to comprehensively reflect obesity-related co-morbidities. Cohen’s κ coefficient was used to evaluate inter-measurement agreement for obesity. Conformity of indirect obesity indicators to the EOSS was assessed based on percentage agreement (proportion classified as obese and severely unhealthy as a result of obesity among the total sample), sensitivity (proportion classified as obese among individuals severely unhealthy as a result of obesity) and specificity (proportion classified as non-obese among fairly healthy individuals). Logistic regression analysis was used to identify the sociodemographic factors most strongly associated with conformity.
The study included 17338 adults from the Korea National Health and Nutrition Examination survey conducted between July 2008 and May 2011.
Level of conformity to the EOSS was highest for WHtR (60·77 %) and lowest for BMI (35·96 %). WHtR and BMI had the highest sensitivity (53·7 %) and specificity (98·4 %), respectively. Predictability of conformity was lower among men for all indirect obesity indicators.
WHtR has the greatest potential to identify individuals at risk of health problems due to obesity. Individual demographic factors must be considered in selecting the most appropriate obesity measurement.
The aims of this study were to investigate the effects of either hearing, vision or dual sensory impairment on depressive symptoms and to identify subgroups that are vulnerable and significantly affected.
Data from the 2006–2014 Korean Longitudinal Study of Aging (KLoSA) were used and a total of 5832 individuals were included in this study. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D10) scale. Sensory impairment was assessed according to the levels of self-reported hearing or vision, which were categorised as either good (excellent, very good or good) or poor (fair or poor). The changes in hearing or vision from records of previous survey were investigated. Changes from good to poor, which indicates new onset, were defined as hearing impairment or vision impairment. Interactions of changes in hearing and vision were considered in the analysis. Dual sensory impairment was indicated when hearing impairment and vision impairment both developed at the same time. Demographic, socioeconomic and health-related factors were considered as potential confounders and were adjusted for in the generalised estimating equation model.
Individuals with hearing impairment demonstrated significantly more severe depressive symptoms [β = 0.434, standard errors (s.e.) = 0.097, p < 0.001] than those who had good hearing. Those with vision impairment also showed significantly elevated depressive symptoms (β = 0.253, s.e. = 0.058, p < 0.001) than those with good vision. When the interactions between hearing and vision were considered, participants with dual sensory impairment showed significantly more severe depressive symptoms (β = 0.768, s.e. = 0.197, p < 0.001) than those with good hearing and vision. The effect of a single and dual sensory impairment on depressive symptoms was significant in both sexes and across age groups, except for vision impairment in male participants.
Hearing, vision and dual sensory impairment are significantly associated with depressive symptoms. Our results suggest that treatment or rehabilitation of either hearing or vision impairment would help prevent depression.
Dementia has negative consequences for both persons with dementia and their family caregivers. Dyadic interventions in which both groups participate together have shown an effective and promising approach. The Couples Life Story Approach (CLSA) that was recently developed for older couples dealing with dementia in the USA was adapted and implemented for the older Korean population in this study. The purpose of this paper is to understand how older Korean couples dealing with dementia experienced the CLSA.
Fifty six couples (n = 102) completed the five-week intervention from December 2013 to October 2015. The participants completed a survey including open-ended questions one week after finishing the intervention. A thematic content analysis was conducted to analyze the responses.
Qualitative analysis revealed benefits and challenges in the experience of CLSA. Themes related to benefits were: (1) emotional benefits of reminiscing; (2) positive evaluation of life as a couple; (3) gratitude toward spouse; (4) changes in communications or activities with spouse; and (5) changes in relationship quality. Couples’ experience varied, with some having mixed feelings about the intervention. Challenges perceived by participants included revival of bitterness and identification of loss.
Findings suggest the CLSA contributes to enhancing the quality of life for couples affected by Alzheimer's disease and improving their relationship. Challenges that emerged in the CLSA will guide future research to identify the sub-population that is appropriate for the couple-oriented intervention in dementia care.
A number of multiple-casualty incidents during 2014 and 2015 brought changes to Korea’s disaster medical assistance system. We report these changes here.
Reports about these incidents, revisions to laws, and the government’s revised medical disaster response guidelines were reviewed.
The number of DMAT (Disaster Medical Assistance Team) staff members was reduced to 4 from 8, and the mobilization method changed. An emergency response manual was created that contains the main content of the DMAT, and there is now a DMAT training program to educate staff. The government created and launched a national 24-hour Disaster Emergency Medical Service Situation Room, and instead of the traditional wireless communications, mobile instant smart phone messaging has been added as a new means of communication. The number of disaster base hospitals has also been doubled.
Although there are still limitations that need to be remedied, the changes to the current emergency medical assistance system are expected to improve the system’s response capacity. (Disaster Med Public Health Preparedness. 2017;11:526–530)
This case study explores how a Chinese-American novice teacher acted as mediator in a telecollaboration with student teacher (ST) peers in the USA who designed tasks for his English as a foreign language (EFL) learners in China. The novice teacher was instrumental in mediating the student teachers’ task design process by providing feedback regarding technological and institutional constraints, and the nuances of his target student population. He appropriated and adapted the tasks to make them relevant for his EFL learners. Against the backdrop of the three dimensions of professional capital – human, social, and decisional – the research questions explored how the novice teacher used the different types of knowledge of context (pedagogical, institutional, technical) in relation to task design, and his perception of his role as mediator. Within a sociocultural framework for telecollaboration studies, this exploratory case study shares characteristics of ethnography, action research, and narrative inquiry. Data triangulation included text-based computer-mediated communication (CMC) data (Google Groups, emails), a narrative written by the novice teacher, and a semi-structured, reflective Skype interview with him. The findings indicate that he demonstrated high commitment, thorough preparation, continuous reflection, and development while navigating between his different roles of mediator, assessor, implementer, and field observer.
We describe the case of a young man with bilateral coronary artery to left ventricular fistula, which was drained via a single, common channel. The anomaly was incidentally detected with coronary CT angiography.
The Saemangeum tidal flat, an important staging site for migratory shorebirds that travel the East Asian-Australasian (EAA) Flyway, was isolated from the eastern Yellow Sea in 2006 as part of a large-scale reclamation project. To gain a better understanding of the impacts that this reclamation has had on the long-distance migratory shorebirds that use the EAA Flyway, we examined the number of shorebirds visiting Saemangeum and three adjacent sites in the Geum Estuary (Yubu Island, the Janghang coastline, and the Geum River Channel) during the spring and fall prior to, and after, completion of the reclamation (2004–2013). A total of 48 shorebird species, including one Critically Endangered, three Endangered, and nine Near Threatened species, were observed over this period. Peak numbers of shorebirds recorded at sites in Saemangeum and the Geum Estuary following completion of the project were 74% below those recorded in 2004 and 2005, the years prior to reclamation activity. In Saemangeum, shorebird abundance declined by approximately 95% and 97.3% during the northward and southward migrations, respectively, as a result of reclamation. Although shorebird populations in the Geum Estuary increased by 5% and 20% during the northwards and southward migrations, respectively, these increases failed to offset the reduction in shorebird abundance in Saemangeum; overall, shorebird abundance at Saemangeum and the three adjacent sites in the Geum Estuary markedly declined over the reclamation period. Given the more favourable conditions of adjacent areas, sites in Saemangeum and the Geum Estuary no longer provide the habitat conditions necessary for long-distance migratory shorebirds. In order to improve habitat for staging migratory birds, we suggest that measures such as the conversion of an abandoned salt farm for use as roosting sites, the construction of artificial barriers to prevent human disturbance, and re-opening of the river-banks to facilitate water flow be implemented.
A life-threatening cardiopulmonary resuscitation (CPR)-related injury can cause recurrent arrest after return of circulation. Such injuries are difficult to identify during resuscitation, and their contribution to failed resuscitation can be missed given the limitations of conventional CPR. Extracorporeal cardiopulmonary resuscitation (ECPR), increasingly being considered for selected patients with potentially reversible etiology of arrest, may identify previously occult CPR-related injuries by restoring arterial pressure and flow. Herein, we describe two cases of severe CPR-related injuries contributing to recurrent arrest. Each case had ECPR implemented within 60 minutes of the start of CPR. After the presumed cardiac etiology had been addressed with percutaneous coronary intervention, life-threatening cardiovascular injuries with recurrent arrest were noted, and resuscitative thoracotomy was performed under ECPR. One patient survived to hospital discharge.
ECPR may provide an opportunity to identify and correct severe resuscitation-related injuries causing recurrent arrest. Chest compression depth >6 cm, especially in older women, may contribute to these injuries.
Hypertension affects older Americans more than any other age group. Not only is hypertension the most common outpatient medical condition in the United States regardless of age, but it poses a unique challenge to those caring for the geriatric population. Adverse outcomes have been shown to decrease with appropriately managed blood pressure. Therefore, it is imperative for health care providers to be adept at individualized therapy for the older adult patient while accounting for likely multiple comorbidities in hopes of preventing kidney failure, stroke, and heart disease.
The fundamentals of the ‘resonance method’ are presented. The method relies on evaluating the dynamic response of one or more dust particles in the sheath of a laboratory plasma to small external perturbations. It allows one to make in situ high-precision measurements of particle properties. It is shown that the particle mass and charge and the strength of the interaction between two particles can be measured. Technical requirements, limitations and application examples are presented and discussed.
Polycyclic aromatic hydrocarbons (PAH) are common dietary exposures that cross the human placenta and are classified as a probable human carcinogen. The aim of the present study was to investigate the potential impact of exposure to PAH-containing meat consumed during pregnancy on birth outcomes.
Prospective birth cohort study. Only non-smoking women with singleton pregnancies, who were free from chronic disease such as diabetes and hypertension, were included in the study. Maternal consumption of PAH-rich meat was estimated through FFQ. Multiple linear regression was used to assess factors related to higher intake and the association between dietary PAH and birth outcomes.
Republic of Korea, 2006–2011.
Pregnant women (n 778) at 12–28 weeks of gestation enrolled in the Mothers and Children’s Environmental Health (MOCEH) study.
The multivariable regression model showed a significant reduction in birth weight associated with higher consumption level of foods rich in PAH, such as grilled or roasted meat, during pregnancy (β=−17·48 g, P<0·05 for every 1 point higher in meat score). Further adjusting for biomarkers of airborne PAH did not alter this association. There was no evidence that higher consumption level of PAH-rich meat shortens the duration of gestation (P=0·561). Regression models performed for birth length and head circumference produced negative effects that were not statistically significant.
Consumption of higher levels of barbecued, fried, roasted and smoked meats during pregnancy was associated with reduced birth weight. Dietary risk of PAH exposure in Korean women is of concern.
We present a new concept applicable to the epitaxial growth of dislocation-free semiconductor structures on a mismatched substrate with a thickness far exceeding the conventional critical thickness for plastic strain relaxation. This innovative concept is based on the out-of-equilibrium growth of compositionally graded alloys on deeply patterned substrates. We obtain space-filling arrays of individual crystals several micrometers wide in which the mechanism of strain relaxation is fundamentally changed from plastic to elastic. The complete absence of dislocations at and near the heterointerface may pave the way to realize CMOS integrated SiGe X-ray detectors.