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Radiocarbon (14C) dating has been widely used to determine the age of deposits, but there have been frequent reports of inconsistencies in age among different dating materials. In this study, we performed radiocarbon dating on a total of 33 samples from 8-m-long sediment cores recovered from the wetland of the Muljangori volcanic cone on Jeju Island, South Korea. Ten pairs of humic acid (HA) and plant fragments (PF) samples, and three pairs of HA and humin samples, from the same depths were compared in terms of age. The PF were consistently younger than the HA. Interestingly, the age difference between HA and PF samples showed a long-term change during the past 8000 years. To test whether there was an association between this long-term age difference and climate change, we compared with the carbon/nitrogen (C/N) ratios and total organic carbon isotope (δ13CTOC) values of the sediments, as indicators of the relative abundance of terrestrial and aquatic plants; these parameters showed similar long-term trends. This suggests that the increasing (decreasing) trend in age difference was influenced by long-term dry (wet) climate change.
In order to maximize the utility of future studies of trilobite ontogeny, we propose a set of standard practices that relate to the collection, nomenclature, description, depiction, and interpretation of ontogenetic series inferred from articulated specimens belonging to individual species. In some cases, these suggestions may also apply to ontogenetic studies of other fossilized taxa.
We calculated the human resources required for an antimicrobial stewardship program (ASP) in Korean hospitals.
Multicenter retrospective study.
Eight Korean hospitals ranging in size from 295 to 1,337 beds.
The time required for performing ASP activities for all hospitalized patients under antibiotic therapy was estimated and converted into hours per week. The actual time spent on patient reviews of each ASP activity was measured with a small number of cases, then the total time was estimated by applying the determined times to a larger number of cases. Full-time equivalents (FTEs) were measured according to labor laws in Korea (52 hours per week).
In total, 225 cases were reviewed to measure time spent on patient reviews. The median time spent per patient review for ASP activities ranged from 10 to 16 minutes. The total time spent on the review for all hospitalized patients was estimated using the observed number of ASP activities for 1,534 patients who underwent antibiotic therapy on surveillance days. The most commonly observed ASP activity was ‘review of surgical prophylactic antibiotics’ (32.7%), followed by ‘appropriate antibiotics recommendations for patients with suspected infection without a proven site of infection but without causative pathogens’ (28.6%). The personnel requirement was calculated as 1.20 FTEs (interquartile range [IQR], 1.02–1.38) per 100 beds and 2.28 FTEs (IQR, 1.93–2.62) per 100 patients who underwent antibiotic therapy, respectively.
The estimated time required for human resources performing extensive ASP activities on all hospitalized patients undergoing antibiotic therapy in Korean hospitals was ~1.20 FTEs (IQR, 1.02–1.38) per 100 beds.
Early replacement of a new central venous catheter (CVC) may pose a risk of persistent or recurrent infection in patients with a catheter-related bloodstream infection (CRBSI). We evaluated the clinical impact of early CVC reinsertion after catheter removal in patients with CRBSIs.
We conducted a retrospective chart review of adult patients with confirmed CRBSIs in 2 tertiary-care hospitals over a 7-year period.
To treat their infections, 316 patients with CRBSIs underwent CVC removal. Among them, 130 (41.1%) underwent early CVC reinsertion (≤3 days after CVC removal), 39 (12.4%) underwent delayed reinsertion (>3 days), and 147 (46.5%) did not undergo CVC reinsertion. There were no differences in baseline characteristics among the 3 groups, except for nontunneled CVC, presence of septic shock, and reason for CVC reinsertion. The rate of persistent CRBSI in the early CVC reinsertion group (22.3%) was higher than that in the no CVC reinsertion group (7.5%; P = .002) but was similar to that in the delayed CVC reinsertion group (17.9%; P > .99). The other clinical outcomes did not differ among the 3 groups, including rates of 30-day mortality, complicated infection, and recurrence. After controlling for several confounding factors, early CVC reinsertion was not significantly associated with persistent CRBSI (OR, 1.59; P = .35) or 30-day mortality compared with delayed CVC reinsertion (OR, 0.81; P = .68).
Early CVC reinsertion in the setting of CRBSI may be safe. Replacement of a new CVC should not be delayed in patients who still require a CVC for ongoing management.
The 14C peak in AD 775 (M12) has been measured and confirmed globally in several studies since it was first measured in annual tree rings by Miyake et al. (2012). However, M12 data measurements in early- and latewood are limited. This paper presents the Δ14C values in early- and latewood from AD 762–776 Zelkova serrata tree rings from Bangu-dong, Ulsan, South Korea (35°33′N, 129°20′E). The results indicate no early rise in Δ14C values in the latewood of AD 774 in this sample located at mid-latitude. A comparison of the results of this and previous studies suggests latitude dependence (Büntgen et al. 2018); that is, the early rise of Δ14C in AD 774 was not observed at mid-latitudes in South Korea but was observed at high latitudes in Finland. The half-oxidation time of 14C was estimated from a detailed analysis of a small bomb peak in AD 1962. Based on the half-oxidation time, the Δ14C rise in the latewood, but not in the earlywood, of AD 774 in Finland, and the absence of a Δ14C rise in both the early- and latewood of AD 774 in South Korea, the 14C spike was estimated to have been produced from late April to mid-June in AD 774.
The experiments reported in this research paper aimed to determine the effect of supplementing different forms of L-methionine (L-Met) and acetate on protein synthesis in immortalized bovine mammary epithelial cell line (MAC-T cells). Treatments were Control, L-Met, conjugated L-Met and acetate (CMA), and non-conjugated L-Met and Acetate (NMA). Protein synthesis mechanism was determined by omics method. NMA group had the highest protein content in the media and CSN2 mRNA expression levels (P < 0.05). The number of upregulated and downregulated proteins observed were 39 and 77 in L-Met group, 62 and 80 in CMA group and 50 and 81 in NMA group from 448 proteins, respectively (P < 0.05). L-Met, NMA and CMA treatments stimulated pathways related to protein and energy metabolism (P < 0.05). Metabolomic analysis also revealed that L-Met, CMA and NMA treatments resulted in increases of several metabolites (P < 0.05). In conclusion, NMA treatment increased protein concentration and expression level of CSN2 mRNA in MAC-T cells compared to control as well as L-Met and CMA treatments through increased expression of milk protein synthesis-related genes and production of the proteins and metabolites involved in energy and protein synthesis pathways.
Migraine with aura is one of the causes of stroke mimics. We retrospectively reviewed the 10-year medical records of patients who were treated with acute stroke management protocol. We analyzed the frequency and characteristics of patients with a final diagnosis of migraine with aura. Among the 1355 patients with stroke mimics, migraine with aura was the final diagnosis in 36 patients (2.7%). The most common auras included sensory and brainstem auras followed by motor, visual, and speech/language auras. One patient manifested transient atrial fibrillation during the migraine attack, which can be a link with acute stroke.
Personality may predispose family caregivers to experience caregiving differently in similar situations and influence the outcomes of caregiving. A limited body of research has examined the role of some personality traits for health-related quality of life (HRQoL) among family caregivers of persons with dementia (PWD) in relation to burden and depression.
Data from a large clinic-based national study in South Korea, the Caregivers of Alzheimer's Disease Research (CARE), were analyzed (N = 476). Path analysis was performed to explore the association between family caregivers’ personality traits and HRQoL. With depression and burden as mediating factors, direct and indirect associations between five personality traits and HRQoL of family caregivers were examined.
Results demonstrated the mediating role of caregiver burden and depression in linking two personality traits (neuroticism and extraversion) and HRQoL. Neuroticism and extraversion directly and indirectly influenced the mental HRQoL of caregivers. Neuroticism and extraversion only indirectly influenced their physical HRQoL. Neuroticism increased the caregiver's depression, whereas extraversion decreased it. Neuroticism only was mediated by burden to influence depression and mental and physical HRQoL.
Personality traits can influence caregiving outcomes and be viewed as an individual resource of the caregiver. A family caregiver's personality characteristics need to be assessed for tailoring support programs to get the optimal benefits from caregiver interventions.
Korea Microlensing Telescope Network (KMTNet) which consists of three identical 1.6 m wide-field telescopes with 18k × 18k CCDs, is the first optical survey system of its kind. The combination of fast optics and the mosaic CCD delivers seeing limited images over a 4 square degrees field of view. The main science goal of KMTNet is the discovery and characterization of exoplanets, yet it also offers various other science applications including DEep Ecliptic Patrol of SOUTHern sky (DEEP-South). The aim of DEEP-South is to discover and characterize asteroids and comets, including Near Earth Objects (NEOs). We started test runs last February after commissioning, and will return to normal operations in October 2015. A summary of early results from the test runs will be presented.
Korea Astronomy and Space Science Institute (KASI) successfully completed the development of Korea Microlensing Telescope Network (KMTNet, Park et al. 2012) in mid-2015, following which it conducted test runs for several months. ‘DEep Ecliptic Patrol of the Southern sky’ (DEEP-South, Moon et al. 2015), which will be used for asteroid and comet studies, will not only characterize targeted asteroids, carrying out blind surveys toward the sweet spots, but will also mine the data of such bodies using the KMTNet archive. We report preliminary lightcurves of four Potentially Hazardous Asteroids (PHAs) from test runs at KMTNet-CTIO in the February - May 2015 period.
We started ‘DEep Ecliptic Patrol of the Southern sky’ (DEEP-South, DS) (Moon et al. 2015) in late 2012, and conducted test runs with the first Korea Microlensing Telescope Network (KMTNet) (Park et al. 2012), a 1.6 m telescope with 18k x 18k CCD stationed at CTIO in early 2015. While the primary objective of DEEP-South is the physical characterization of small Solar System bodies, it is also expected to discover a large number of such bodies, many of them previously unknown. An automated observation scheduling, data reduction and analysis software subsystem called ‘DEEP-South Scheduling and Data reduction System’ (DS SDS) is thus being designed and implemented to enable observation planning, data reduction and analysis with minimal human intervention.
Cerebral white matter hyperintensities (WMH) are prevalent incident findings on brain MRI scans among elderly people and have been consistently implicated in cognitive dysfunction. However, differential roles of WMH by region in cognitive function are still unclear. The aim of this study was to ascertain the differential role of regional WMH in predicting progression from mild cognitive impairment (MCI) to different subtypes of dementia.
Participants were recruited from the Clinical Research Center for Dementia of South Korea (CREDOS) study. A total of 622 participants with MCI diagnoses at baseline and follow-up evaluations were included for the analysis. Initial MRI scans were rated for WMH on a visual rating scale developed for the CREDOS. Differential effects of regional WMH in predicting incident dementia were evaluated using the Cox proportional hazards model.
Of the 622 participants with MCI at baseline, 139 patients (22.3%) converted to all-cause dementia over a median of 14.3 (range 6.0–36.5) months. Severe periventricular WMH (PWMH) predicted incident all-cause dementia (Hazard ratio (HR) 2.22; 95% confidence interval (CI) 1.43–3.43) and Alzheimer's disease (AD) (HR 1.86; 95% CI 1.12–3.07). Subcortical vascular dementia (SVD) was predicted by both PWMH (HR 16.14; 95% CI 1.97–132.06) and DWMH (HR 8.77; 95% CI 1.77–43.49) in more severe form (≥ 10 mm).
WMH differentially predict dementia by region and severity. Our findings suggest that PWMH may play an independent role in the pathogenesis of dementia, especially in AD.
Decreased hemoglobin levels increase the risk of developing dementia among the elderly. However, the underlying mechanisms that link decreased hemoglobin levels to incident dementia still remain unclear, possibly due to the fact that few studies have reported on the relationship between low hemoglobin levels and neuroimaging markers. We, therefore, investigated the relationships between decreased hemoglobin levels, cerebral small-vessel disease (CSVD), and cortical atrophy in cognitively healthy women and men.
Cognitively normal women (n = 1,022) and men (n = 1,018) who underwent medical check-ups and magnetic resonance imaging (MRI) were enrolled at a health promotion center. We measured hemoglobin levels, white matter hyperintensities (WMH) scales, lacunes, and microbleeds. Cortical thickness was automatically measured using surface based methods. Multivariate regression analyses were performed after controlling for possible confounders.
Decreased hemoglobin levels were not associated with the presence of WMH, lacunes, or microbleeds in women and men. Among women, decreased hemoglobin levels were associated with decreased cortical thickness in the frontal (Estimates, 95% confidence interval, −0.007, (−0.013, −0.001)), temporal (−0.010, (−0.018, −0.002)), parietal (−0.009, (−0.015, −0.003)), and occipital regions (−0.011, (−0.019, −0.003)). Among men, however, no associations were observed between hemoglobin levels and cortical thickness.
Our findings suggested that decreased hemoglobin levels affected cortical atrophy, but not increased CSVD, among women, although the association is modest. Given the paucity of modifiable risk factors for age-related cognitive decline, our results have important public health implications.
The present study was performed to investigate whether breast-feeding is associated with early pubertal development among children 7–9 years old in Korea.
Children were divided into those who did and did not receive breast-feeding for 6 months or longer in accordance with the recommendations of the WHO. Pubertal status was determined by clinical examination using Tanner staging.
Prospective observational study.
We conducted a follow-up study of children aged 7–9 years in 2011 who had taken part in the Ewha Birth & Growth Cohort study.
Fifty (22·8 %) of the total of 219 children were in early puberty, with the proportion being slightly higher for girls (24·1 %) than boys (21·4 %). Children who had entered early puberty were taller, weighed more and had a higher concentration of insulin-like growth factor 1. Moreover, the change in weight Z-score from birth to follow-up was significantly lower in children who were breast-fed than in those who were not (weight Z-score change: 0·32 (sd 1·59) v. 0·77 (sd 1·61), respectively, P=0·04). Comparison of breast-feeding by puberty status indicated a preventive association with early puberty in children who were breast-fed for 6 months or longer (OR=0·37; 95 % CI 0·18, 0·74). This association remained significant after adjustment for relevant covariates.
These results demonstrate a beneficial association between breast-feeding and early pubertal development, especially in those breast-fed for 6 months or longer. The study suggests that interventions would need to start early in life to prevent early pubertal development.
In this review paper, we introduce a self-phase controlled stimulated Brillouin scattering phase conjugate mirror (SC-SBS-PCM) and the Kumgang laser. The SC-SBS-PCM was proposed and demonstrated its success at the academic low power level,
. The Kumgang laser is under development to verify whether the SC-SBS-PCM is operable at the kW level. It is a 4 kW beam combination laser combining four 1 kW beams using the SC-SBS-PCM. If the Kumgang laser functions successfully, it will be the most important step towards a Dream laser, a hypothetical laser with unlimited power and a high repetition rate.
Nitrogen (N) and boron (B) codoped diamond-like carbon (DLC) films were prepared on silicon oxide substrates by RF magnetron sputtering to optimize the electrical conductivity and hardness of DLC film. The electrical conductivity and hardness of the N–B codoped DLC films were controlled simultaneously by varying N2 flow rate with fixed B target power and varying B target power with fixed N2flow rate. The electrical resistivity of the B-doped DLC films showed a cup-shaped relationship with B target power and a U-shaped relationship with the N–B codoped DLC film. However, hardness of the B-doped DLC films showed a decreasing behavior but it was maintained almost constant for the N–B codoped DLC film. These particular electrical and hardness behaviors of the N–B codoped DLC films could be explained by a neutralization effect of N and B codoping.
We have compiled and analyzed historical meter and meteor shower records in Korean, Chinese, and Japanese chronicles. We have confirmed the peaks of Perseids and an excess due to the mixture of Orionids, north-Taurids, or Leonids through the Monte-Carlo test from the Korean records. The peaks persist for almost one thousand years. We have also analyzed seasonal variation of sporadic meteors from Korean records. Major features in Chinese meteor shower records are quite consistent with those of Korean records, particularly for the last millennium. Japanese records also show Perseids feature and Orionids/north-Taurids/Leonids feature, although they are less prominent compared to those of Korean or Chinese records.
ZnS:Cu,Cl,Mn,Te, which shows red AC powder electroluminescence (ACPEL) emission, was synthesized using a conventional wet synthesis and a sealed vessel method. The photoluminescence (PL) and ACPEL were characterized. After the second firing, 0.5 wt% tellurium (Te)-doped ZnS:Cu,Cl,Mn,Te phosphor shows almost red PL emission from the 4T1–6A1 transition of Mn2+ ions, which are affected by the Te. Extended x-ray absorption fine structure analysis on the Mn K edge proved that the substitution of sulfur (S) with Te changes the local crystal field of the Mn2+ ions and shifts an orange emission (∼588 nm) to a red emission (∼650 nm). A red ACPEL emission is first shown in 0.5 wt%Te-doped ZnS:Cu,Cl,Mn,Te after the third firing phosphor even though its luminance is not very high. The origin of the ACPEL emission is assumed to be not a CuxS–ZnS p–n junction but a CuxTe–ZnS p–n junction. Raman spectra were characterized to support that the red ACPEL emission is probably attributed to a CuxTe–ZnS p–n junction.
The oocyte is known from recent studies in the mouse, cow, sheep and human to be a central regulator of follicular cell function. However, in the pig, little information is known about the regulation of cumulus expansion by oocyte-secreted factors and oocyte quality. We investigated the possible effects of oocyte-secreted factors during in vitro maturation on cumulus expansion and on porcine oocytes as judged by subsequent embryonic development after parthenogenetic activation. Cumulus–oocyte complexes (COC) from antral follicles of pig ovaries collected from a local abattoir were divided into control and treatment groups and were cultured in tissue culture medium 199 supplemented with follicle-stimulating hormone. Treatment groups consisted of increasing numbers of denuded oocytes (DO) co-cultured with COC (at ratios of COC to DO of 1:1, 1:2, 1:3, 1:4 and 1:5). After incubation for 44 h, cumulus expansion and maturation rates were assessed and oocytes were activated parthenogenetically. Cumulus expansion in the 1 COC:4 DO and 1 COC:5 DO groups was low and altered because full dispersion of the outer layer did not occur. Cell viability was not affected, as measured by the automated cell counter, but scanning electron microscopy revealed only a scanty extracellular matrix. Blastocyst rate was significantly higher in the 1 COC:4 DO (34.4%) and in the 1 COC:5 DO (34.9%) groups (p < 0.05) when compared with other groups. Maturation rate, cleavage rate and total cell number showed no significant difference between control and treatment groups. Amplification by reverse transcription polymerase chain reaction (RT-PCR) showed up-regulation of growth differentiation factor 9 (GDF9) in the cumulus cells in the 1 COC:4 DO group at 44 h. We conclude that denuded porcine oocytes could improve the maturation of COC as evidenced by increased blastocyst development in the 1 COC:4 DO, even though cumulus expansion was poor. This improvement could be a result of the GDF9 up-regulation.