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Identification of geographical areas with high burden of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission in schools using spatial analyses has become an important tool to guide targeted interventions in educational setting. In this study, we aimed to explore the spatial distribution and determinants of coronavirus disease 2019 (COVID-19) among students aged 3–18 years in South Korea. We analysed the nationwide epidemiological data on laboratory-confirmed COVID-19 cases in schools and in the communities between January 2020 and October 2021 in South Korea. To explore the spatial distribution, the global Moran's I and Getis-Ord's G using incidence rates among the districts of aged 3–18 years and 30–59 years. Spatial regression analysis was performed to find sociodemographic predictors of the COVID-19 attack rate in schools and in the communities. The global spatial correlation estimated by Moran's I was 0.647 for the community population and 0.350 for the student population, suggesting that the students were spatially less correlated than the community-level outbreak of SARS-CoV-2. In schools, attack rate of adults aged 30–59 years in the community was associated with increased risk of transmission (P < 0.0001). Number of students per class (in kindergartens, primary schools, middle schools and high schools) did not show significant association with the school transmission of SARS-CoV-2. In South Korea, COVID-19 in students had spatial variations across the country. Statistically significant high hotspots of SARS-CoV-2 transmission among students were found in the capital area, with dense population level and high COVID-19 burden among adults aged 30–59 years. Our finding suggests that controlling community-level burden of COVID-19 can help in preventing SARS-CoV-2 infection in school-aged children.
Several studies supported the usefulness of “the surprise question” in terms of 1-year mortality of patients. “The surprise question” requires a “Yes” or “No” answer to the question “Would I be surprised if this patient died in [specific time frame].” However, the 1-year time frame is often too long for advanced cancer patients seen by palliative care personnel. “The surprise question” with shorter time frames is needed for decision making. We examined the accuracy of “the surprise question” for 7-day, 21-day, and 42-day survival in hospitalized patients admitted to palliative care units (PCUs).
This was a prospective multicenter cohort study of 130 adult patients with advanced cancer admitted to 7 hospital-based PCUs in South Korea. The accuracy of “the surprise question” was compared with that of the temporal question for clinician's prediction of survival.
We analyzed 130 inpatients who died in PCUs during the study period. The median survival was 21.0 days. The sensitivity, specificity, and overall accuracy for the 7-day “the surprise question” were 46.7, 88.7, and 83.9%, respectively. The sensitivity, specificity, and overall accuracy for the 7-day temporal question were 6.7, 98.3, and 87.7%, respectively. The c-indices of the 7-day “the surprise question” and 7-day temporal question were 0.662 (95% CI: 0.539–0.785) and 0.521 (95% CI: 0.464–0.579), respectively. The c-indices of the 42-day “the surprise question” and 42-day temporal question were 0.554 (95% CI: 0.509–0.599) and 0.616 (95% CI: 0.569–0.663), respectively.
Significance of results
Surprisingly, “the surprise questions” and temporal questions had similar accuracies. The high specificities for the 7-day “the surprise question” and 7- and 21-day temporal question suggest they may be useful to rule in death if positive.
It is unclear how brain reserve interacts with gender and apolipoprotein E4 (APOE4) genotype, and how this influences the progression of Alzheimer's disease (AD). The association between intracranial volume (ICV) and progression to AD in subjects with mild cognitive impairment (MCI), and differences according to gender and APOE4 genotype, was investigated.
Data from subjects initially diagnosed with MCI and at least two visits were downloaded from the ADNI database. Those who progressed to AD were defined as converters. The longitudinal influence of ICV was determined by survival analysis. The time of conversion from MCI to AD was set as a fiducial point, as all converters would be at a similar disease stage then, and longitudinal trajectories of brain atrophy and cognitive decline around that point were compared using linear mixed models.
Large ICV increased the risk of conversion to AD in males (HR: 4.24, 95% confidence interval (CI): 1.17–15.40) and APOE4 non-carriers (HR: 10.00, 95% CI: 1.34–74.53), but not in females or APOE4 carriers. Cognitive decline and brain atrophy progressed at a faster rate in males with large ICV than in those with small ICV during the two years before and after the time of conversion.
Large ICV increased the risk of conversion to AD in males and APOE4 non-carriers with MCI. This may be due to its influence on disease trajectory, which shortens the duration of the MCI stage. A longitudinal model of progression trajectory is proposed.
The thickness dependence of the electrical stability under monotonic and cyclic tensile loading is investigated for Cu films on polymer substrates. As for monotonic tensile deformation, thicker films show better stability than thinner films due to their higher ductility and the larger capability of strain accommodation. For the fatigue resistance, however, a more complex behavior was observed depending on the amount of the applied strain. For low strain amplitude in the high cycle fatigue (HCF) regime, thinner films exhibit longer fatigue life because the larger strength of thinner films suppresses dislocation movement and damage nucleation. However, for high strain amplitudes in the low cycle fatigue (LCF) regime, the fatigue life for thinner films is drastically reduced compared to thicker films. It is shown that fatigue coefficients in the LCF regime can be obtained when applying the Coffin–Manson relationship.
The study's aim was to examine the association of alcohol consumption with verbal and visuospatial memory impairment in older people.
Participants were 1,572, aged ≥60 years, in the hospital-based registry of the Clinical Research Center for Dementia of South Korea (CREDOS). Moderate drinking was defined as no more than seven drinks per week and three drinks per day. Memory impairment was defined as performance with more than 1 standard deviation below the mean value on the Seoul Verbal Learning Test and Rey Complex Figure Test.
Those who consumed alcohol moderately, compared with abstainers, had a lower odds of verbal memory impairment (Odds Ratio [OR] = 0.64; 95% Confidence Interval [CI]: 0.46–0.87), adjusting for covariates. Visuospatial memory, however, was not significantly associated with alcohol consumption.
Moderate alcohol drinking is associated with a reduced likelihood of verbal memory impairment among older people attending memory clinics.
Pathological gambling (PG) is a severe and persistent pattern of problem gambling that has been aligned with obsessive-compulsive disorder (OCD). However, no study has compared the neurocognitive profiles of individuals with PG and OCD.
We compared neurocognitive functioning, including executive function, verbal learning and memory, and visual–spatial organization and memory among 16 pathological gamblers, 31 drug-naïve OCD subjects, and 52 healthy controls.
The only neurocognitive marker common to both groups was increased fragmentation errors on the Rey–Osterrieth Complex Figure Test (ROCF). The PG subjects showed increased nonperseverative error on the Wisconsin Card Sorting Test and organization difficulties in the ROCF, whereas the OCD subjects revealed longer response times on the Stroop test and retention difficulties on the immediate recall scale of the ROCF.
A more careful approach is required in considering whether PG is a part of the OCD spectrum, as little evidence of neurocognitive overlap between PG and OCD has been reported.
We investigated the catheterization and angiographic findings of 26 patients with Williams‘ syndrome to evaluate the natural course of supravalvar aortic stenosis and peripheral pulmonary arterial stenosis. The severity of the stenosis was correlated with age and body surface area in terms of the pulmonary arterial index, right ventricular systolic pressure, sinutubular ratio(ratio of measured to mean normal diameter of sinutubular junction), and systolic pressure gradient across the sinutubular junction. In patients with pulmonary arterial stenosis (n=20), right ventricular systolic pressure tended to decrease, and pulmonary arterial index increased, with increase in age and body surface area. Between the groups with and without pulmonary arterial stenosis, there was significant difference in age (mean 4.70 vs. 9.87, p = 0.019), body surface area (0.62 vs. 1.16, p = 0.002), pulmonary arterial index (152 vs. 317, p=0.002) and right ventricular systolic pressure (73.9 vs. 33.0, p=0.006). As all patients showed similar diameters at the sinutubular junction regardless of age and body size, sinutubular ratio decreased with increases in age and body surface area. The group with abnormal coronary arteries (n = 7) had smaller sinutubular ratio (0.46 vs. 0.61, p=0.021) and higher pressure gradients between the left ventricle and the aorta (67.6 vs. 42.2, p=0.023) than did the group with normal coronary arteries. Stenosis of a coronary artery, or a branch of the aortic arch, was observed only in three patients with diffuse aortic stenosis.
Our results suggest that, with time, peripheral pulmonary arterial stenosis tends to improve, and supravalvar aortic stenosis to progress. Failure of growth of the sinutubular junction might be responsible for the progression of the aortic lesion. Progression of the aortic lesion may be associated with involvement of the coronary arteries.
MgO thin films are widely used in plasma display panels (PDPs) to protect the dielectric layer, which is composed of PbO2, B2O3, and SiO2 compound, against ion bombardment during discharge. To improve the electrical properties of the MgO thin films, (Ba,Sr,Ca)CO3 or LaB6, which has a lower work function than that of MgO, added to the MgO films. The effects of (Ba,Sr,Ca)CO3 or LaB6 addition on the electrical properties, microstructure, and electronic band structure were investigated. In the case where (Ba,Sr,Ca)CO3 was added, the firing voltage, which is the voltage when the panel is ignited the first time during increasing input voltage, was about 18.4 V lower than that of the conventional MgO films. In the case where LaB6 was added, the firing voltage was also reduced by about 24 V. The luminance and luminous efficiency were also increased. Of particular interest was the valence band spectra changed after adding (Ba,Sr,Ca)CO3 or LaB6. The valence band edge, which is the top of the valence band, was shifted to lower binding states and the width of the valence band was increased. Moreover, the band gap was slightly reduced. Considering the emission mechanism of MgO films in plasma display panels, these results mean that the secondary electrons can be ejected more easily and the ejected electrons have more energy. Therefore, the addition of (Ba,Sr,Ca)CO3 or LaB6 might improve the electrical properties.
Lithium based complex hydrides, including lithium aluminum hydrides and lithium borohydride (LiAlH4, Li3AlH6 and LiBH4), are among the most promising materials due to their high hydrogen contents. In the present work, we investigated the hydrogen storage properties of a new combined system of Li3AlH6-LiBH4. The samples were made with small amounts of catalyst under low energy milling conditions. Thermogravimetric analysis (TGA) of a Ti-doped Li3AlH6/2LiBH4 indicated that the degree of hydrogen release reached 7.3 wt. % by the time the sample reached 450iÆc under a heating rate of 2iÆC/min. This increased to 8.8 wt. % when the sample was held at 450iÆCfor additional 8 hours minutes under this condition. The dehydrogenation product was a mixture of LiH and AlB2. This product could be rehydrogenated up to 3.8 wt. % under 24.1 MPa hydrogen pressure and 450iÆC.
Asian plantain (Plantago asiatica) essential oil (PAEO) contains multiple bioactive compounds, but its potential effects on lipid metabolism have not been examined. PAEO was found to be mostly composed of oxygenated monoterpenes, with linalool as the major component (82·5 %, w/w), measured using GC–MS. Incubation of 0–200 μg PAEO/ml with HepG2 cells for 24 h resulted in no significant toxicity. Incubation with 0·2 mg PAEO/ml altered the expression of LDL receptor (+83 %; P < 0·05) and 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase ( − 37 %; P < 0·05), as assessed using RT-PCR. LDL oxidation was markedly inhibited by PAEO treatment due to the prevalence of linalool compounds in PAEO. Oral administration of PAEO for 3 weeks in C57BL/6 mice significantly reduced plasma total cholesterol and TAG concentrations by 29 and 46 %, respectively. The mRNA (+58 %; P < 0·05), but not protein, levels of the LDL receptor were significantly higher, whereas both mRNA and protein levels of HMG-CoA reductase were significantly lower ( − 46 and − 11 %, respectively; P < 0·05) in the liver of PAEO-fed than of control mice. The mRNA levels of CYP7A1 were marginally reduced in HepG2 cells, but not in mouse liver after PAEO treatment. Thus, PAEO may have hypocholesterolaemic effects by altering the expression of HMG-CoA reductase. Reduced TAG and oxidised LDL may provide additional cardiovascular protective benefits.
To determine the appropriateness of antibiotic prophylaxis regimens for major surgery in Korea.
Retrospective study using a written survey for each patient who underwent arthroplasty, colon surgery, or hysterectomy.
Six tertiary hospitals in Seoul and Gyeonggi Province.
From each hospital, a maximum of 150 patients who underwent each type of surgery were randomly chosen for the study.
Of 2,644 eligible patients, 1,914 patients were included in the analysis; 677 of these patients underwent arthroplasty, 578 underwent colon surgery, and 659 underwent hysterectomy. Nineteen patients were excluded from the analyses of the class and number of antibiotics used for prophylaxis because they underwent multiple surgeries at different sites. For each of the 1,895 remaining patients, antibiotic prophylaxis involved a mean ( ± SD) of 2.8 ± 0.9 classes of antibiotics. The most commonly prescribed agents were cephalosporins (prescribed for 1,875 [98.9%] of the patients) and aminoglycosides (1,404 [74.1%]). A total of 1,574 (83.1%) of patients received at least 2 classes of antibiotics simultaneously. Only 15 (0.8%) of 1,895 patients received antibiotic prophylaxis in accordance with published guidelines. Of 506 patients for whom the initial dose of antibiotics was evaluated, 374 (73.9%) received an appropriate initial dose. Of the 1,676 patients whose medical records included information about antibiotic administration relative to the time of surgery, only 188 (11.2%) received antibiotic prophylaxis an hour or less before the surgical incision was made. Of the 1,748 patients whose medical records included information about duration of surgery, antibiotic prophylaxis was discontinued 24 hours or less after surgery for only 3 (0.2%) of the patients.
Most patients who had major surgery in Korea received inappropriate antibiotic prophylaxis. Measures to improve the appropriateness of antibiotic prophylaxis are urgently required.
We present the formation of SnO2-In2O3 hetero nanostructures. Kinetically, SnO2 nanowires form prior to the heterostructure. In2O3shell was regularly distributed on the SnO2 nanowire surface, and form sheath subsequently. We theoretically explained the morphological evolution of an anisotropic heterostructure such as core-sheath structure.
Metal hydrides and amides are potential candidate materials for hydrogen storage. Lithium- and magnesium-based material systems are among the most promising materials owing to their high hydrogen contents. In the present work, we investigated hydrogenation/dehydrogenation reactions of a binary nitride, LiMgN. LiMgN can be formed by a reaction of MgH2 with LiNH2 in 1:1 ratio. The reaction also releases approximately ∼ 8.1 wt% H2 (theoretical value is 8.2 wt%) between 160 and 220 °C. The reaction product LiMgN can be rehydrogenated by reacting with H2 under 2000 psi of hydrogen pressure and 160 °C with small amount of TiCl3 doping. TGA results showed that about 8.0 wt% of hydrogen was stored in TiCl3-doped LiMgN during the hydrogenation process. The reversible hydrogenation and dehydrogenation mechanisms involving LiMgN and H2 are discussed.
Phylogenetic analysis of the ITS rDNA region was carried out with two economically important downy mildews, Pseudoperonospora cubensis, which infects species of Cucumis, Cucurbita, and Citrullus belonging to Cucurbitaceae, and P. humuli, which infects plants of the genus Humulus belonging to Cannabaceae. Two closely related species, P. cannabina and P. celtidis, were also included to reveal taxonomic relationships with the first two mildews. All four species formed a well-resolved clade when compared with the ITS sequences of other downy mildew genera, using Bayesian inference and maximum parsimony. The P. cubensis isolates obtained from different hosts and (or) geographical origins in Korea, exhibited no intraspecific variability in the ITS sequences. The phylogenetic analyses of P. cubensis and P. humuli showed that they share a high level of sequence homology; the morphology of the sporangiophores, sporangia, and dehiscence apparatus confirmed the similarity of the two species. We therefore reduce P. humuli to the status of a taxonomic synonym of P. cubensis.
Sequence analysis of the ITS region of rDNA was used to investigate the level of genetic diversity occurring within Hyaloperonospora parasitica, and to show the relationship between phylogenies of these fungi and their hosts (Brassicaceae). Maximum parsimony and neighbour-joining analyses were performed using sequences from 32 isolates of Hyaloperonospora and Perofascia, which infect core brassicaceous hosts. For comparison, five isolates of Peronospora were also studied. The constructed phylogenetic trees showed trichotomy, showing that Hyaloperonospora, Perofascia, and Peronospora have different evolutionary histories. Although isolates from Peronospora and Perofascia clearly formed respective clades, the Hyaloperonospora group allowed separation of the isolates into four distinct clades, which shared significantly low sequence similarities. We suggest that H. parasitica infecting brassicaceous hosts should be divided into a number of distinct species. The comparison of the phylogeny of H. parasitica and that of the Brassicaceae suggests that this fungus is closely related with tribes Arabidae and Brassiceae within this host family, illustrating the potential of downy mildews for co-evolution with their hosts.
Surface acoustic wave (SAW) propagation properties of gallium nitride (GaN) epitaxial layers on sapphire were theoretically and experimentally characterized. GaN thin films were grown on a c-plane sapphire substrate using a metalorganic chemical vapor deposition system. The experimental characterization of SAW propagation properties was performed with a linear array of interdigital transducer structures, while SAW velocities were calculated by matrix methods. Experimentally, we found pseudo-SAW and high-velocity pseudo-SAW modes in the GaN/sapphire structure, which had a good agreement with calculated velocities.
The formation of turbostratic boron nitride (tBN) phase on the cubic boron nitride (cBN) phase was investigated at specific conditions. The cBN film was deposited on the Si substrate by unbalanced magnetron sputtering. When the bias voltage at the substrate was adjusted to –85 V, the tBN phase nucleated on the cBN phase and grew simultaneously with the cBN phase. This was a critical bias voltage below which only the tBN phase was formed. The surface morphology of this film was typically shown as nodules dispersed on a very flat surface. The formation of nodulelike tBN phases seemed to be caused by a small variation of local stress on the growth surface. Once the nucleation of the nodulelike tBN phase occurred, the growth of tBN phase was accelerated. Transmission electron microscopy result showed evidence of the stress relaxation of the film caused by the formation of tBN phase at the interface of the tBN and cBN phases.
Mixed ionic-electronic conductors (MIECs) which have both ionic and electronic species as charge carriers have a wide range of applications, such as electrodes in fuel cells, electrocatalytic reactors, and gas separating membranes. They may have either electronic or ionic species as the majority charge carriers. In addition to the single-phase mixed conductors, they may be fabricated by mixing two different phases of materials. Although these composites have been less studied than the single phase MIECs, the combined properties are often superior to single phase MIECs, and properties not seen in an individual phase may appear in the composite phase.
YSZ-based composite systems were chosen to test the effect of transition-metal-oxide (TMO) addition on the electronic conductivity of composite. To induce mixed conductivity, electronic-conducting TMOs such as NiO and Mn2O3 were added into YSZ above the solubility limit. While the solid solubility of NiO in YSZ is limited that of Mn2O3 is large.
In this work, mixed conducting yttria (8 mol%) stabilized zirconia (YSZ) - TMO composites were prepared in full composition range and the electrical conductivity of the composites was measured by 4-probe d.c. conductivity. Electromotive force (emf) measurements of the galvanic cell, current-voltage (I-V) measurements in ion blocking condition and the oxygen-partial-pressure dependent conductivity have been used to determine the contribution of the ionic and electronic charge carriers on the conductivity. Thus the composition-dependent electrical properties were used to explain the percolation behavior of electronic charge carriers in ionic matrix.
Although the total conductivity of dense YSZ-TMO composite was variable with TMO content, the partial-electronic conductivity increased and the ionic conductivity decreased. The composition-dependent conductivity was discussed.
BN films consisting of c-BN and h-BN phases were synthesized using an ion-beam-assisted deposition process. In contrast to conventional observations, the c-BN and h-BN phases did not form separate layers, but were distributed in the form of nano-sized grains throughout the film thickness. No distinctly aligned h-BN layer was observed before the c-BN phase. Such a mixed character of the film was attributed to a localized ion bombardment effect instead of the macro-stress. Possibly because of the presence of scattered h-BN phases, the thin film described here possessed a low hardness of about 20 GPa and a low stress of about 5 GPa, compared with other reported c-BN-containing films.
We have investigated the stress interaction between via and polygranular cluster in the pure Al line using 1-dimensional computer simulation. The conventional belief was that the fastest stress evolution at the via occurs when the polygranular cluster is just below (or above) the via. However, the electromigration induced stress at the via would be faster when a cluster is apartfrom via because the stress interaction between via and clusters may assist electromigration. We simulated the time that the via reaches a certain stress value as a function of the distance of the cluster. It gives a specific distance where the time was minimum (i.e the fastest stress evolution). We named the position as the Fastest Stress Enhancing Polygranular cluster Position (FaSEPP). As a function of the current density, the FaSEPP decreases.
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