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result(s) for
"Cho, Wonyoung"
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Heterotic Kerr-Schild double field theory and classical double copy
by
Cho, Wonyoung
,
Lee, Kanghoon
in
Classical and Quantum Gravitation
,
Classical Theories of Gravity
,
Elementary Particles
2019
A
bstract
We discuss the generalization of the Kerr-Schild (KS) formalism for general relativity and double field theory (DFT) to the heterotic DFT and supergravity. We first introduce a heterotic KS ansatz by introducing a pair of null
O
(
d, d
+
G
) generalized tangent vectors. The pair of null vectors are represented by a pair of
d
-dimensional vector fields, and one of the vector fields is not a null vector. This implies that the null property of the usual KS formalism, which plays a crucial role in linearizing the field equations, can be partially relaxed in a consistent way. We show that the equations of motion under the heterotic KS ansatz in a flat background can be reduced to linear equations. Using the heterotic KS equations, we establish the single and zeroth copy for heterotic supergravity and derive the Maxwell and Maxwell-scalar equations. This agrees with the KLT relation for heterotic string theory.
Journal Article
Machine Learning–Based Prediction of Suicidality in Adolescents With Allergic Rhinitis: Derivation and Validation in 2 Independent Nationwide Cohorts
by
Fond, Guillaume
,
Lee, Hayeon
,
Cho, Joong Ki
in
Academic achievement
,
Adolescent
,
Child psychopathology
2024
Given the additional risk of suicide-related behaviors in adolescents with allergic rhinitis (AR), it is important to use the growing field of machine learning (ML) to evaluate this risk.
This study aims to evaluate the validity and usefulness of an ML model for predicting suicide risk in patients with AR.
We used data from 2 independent survey studies, Korea Youth Risk Behavior Web-based Survey (KYRBS; n=299,468) for the original data set and Korea National Health and Nutrition Examination Survey (KNHANES; n=833) for the external validation data set, to predict suicide risks of AR in adolescents aged 13 to 18 years, with 3.45% (10,341/299,468) and 1.4% (12/833) of the patients attempting suicide in the KYRBS and KNHANES studies, respectively. The outcome of interest was the suicide attempt risks. We selected various ML-based models with hyperparameter tuning in the discovery and performed an area under the receiver operating characteristic curve (AUROC) analysis in the train, test, and external validation data.
The study data set included 299,468 (KYRBS; original data set) and 833 (KNHANES; external validation data set) patients with AR recruited between 2005 and 2022. The best-performing ML model was the random forest model with a mean AUROC of 84.12% (95% CI 83.98%-84.27%) in the original data set. Applying this result to the external validation data set revealed the best performance among the models, with an AUROC of 89.87% (sensitivity 83.33%, specificity 82.58%, accuracy 82.59%, and balanced accuracy 82.96%). While looking at feature importance, the 5 most important features in predicting suicide attempts in adolescent patients with AR are depression, stress status, academic achievement, age, and alcohol consumption.
This study emphasizes the potential of ML models in predicting suicide risks in patients with AR, encouraging further application of these models in other conditions to enhance adolescent health and decrease suicide rates.
Journal Article
Global prevalence of functional dyspepsia according to Rome criteria, 1990–2020: a systematic review and meta-analysis
2024
Although functional dyspepsia (FD) is a common functional gastroduodenal disorder with a high socioeconomic burden, little is known about its global prevalence. Thus, we performed a comprehensive study to estimate long-term trends in the prevalence of FD. We searched PubMed/MEDLINE, Embase, and Google Scholar from 1990 to 2022 for population-based studies that reported the prevalence of FD in adults (≥ 18 years old) according to Rome I, II, III, or IV criteria. The prevalence of FD was extracted from included studies to obtain pooled prevalence with 95% confidence intervals (CI) and 95% prediction intervals. Subgroup analysis was performed according to certain characteristics, including geographic region. A total of 44 studies met the eligibility criteria, including 256,915 participants from 40 countries across six continents. The overall global pooled prevalence of FD was 8.4% (95% CI 7.4–.9.5). The prevalence was the highest in Rome I (11.9%; 95% CI 5.1–25.4) and lowest in Rome IV (6.8%; 95% CI 5.8–7.9). Developing countries showed a higher prevalence than developed countries (9.1% versus 8.0%), and prevalence was higher in women, irrespective of the definition used (9.0% versus 7.0%). The pooled prevalence gradually decreased from 1990 to 2020 (12.4% [8.2–18.3] in 1990–2002 versus 7.3% [6.1–8.7] in 2013–2020). The prevalence of FD differs by country, economic status, geographical region, and sex, and the global prevalence has been gradually declining. Despite the heterogeneity of sample population, our study estimates the current global burden of FD and provides information to heath care policy decisions.
Journal Article
Quantification of identifying cognitive impairment using olfactory-stimulated functional near-infrared spectroscopy with machine learning: a post hoc analysis of a diagnostic trial and validation of an external additional trial
2023
Background
We aimed to quantify the identification of mild cognitive impairment and/or Alzheimer’s disease using olfactory-stimulated functional near-infrared spectroscopy using machine learning through a post hoc analysis of a previous diagnostic trial and an external additional trial.
Methods
We conducted two independent, patient-level, single-group, diagnostic interventional trials (original and additional trials) involving elderly volunteers (aged > 60 years) with suspected declining cognitive function. All volunteers were assessed by measuring the oxygenation difference in the orbitofrontal cortex using an open-label olfactory-stimulated functional near-infrared spectroscopy approach, medical interview, amyloid positron emission tomography, brain magnetic resonance imaging, Mini-Mental State Examination, and Seoul Neuropsychological Screening Battery.
Results
In total, 97 (original trial) and 36 (additional trial) elderly volunteers with suspected decline in cognitive function met the eligibility criteria. The statistical model reported classification accuracies of 87.3% in patients with mild cognitive impairment and Alzheimer’s disease in internal validation (original trial) but 63.9% in external validation (additional trial). The machine learning algorithm achieved 92.5% accuracy with the internal validation data and 82.5% accuracy with the external validation data. For the diagnosis of mild cognitive impairment, machine learning performed better than statistical methods with internal (86.0% versus 85.2%) and external validation data (85.4% versus 68.8%).
Interpretation
In two independent trials, machine learning models using olfactory-stimulated oxygenation differences in the orbitofrontal cortex were superior in diagnosing mild cognitive impairment and Alzheimer’s disease compared to classic statistical models. Our results suggest that the machine learning algorithm is stable across different patient groups and increases generalization and reproducibility.
Trial registration
Clinical Research Information Service (CRiS) of Republic of Korea; CRIS numbers, KCT0006197 and KCT0007589.
Graphical Abstract
Journal Article
0150 Increased Prevalence of Clinical Depression in Late Teens with Sleep Complaints
2023
Introduction Adolescent mental health is becoming clinical attention since suicide is one of the leading causes of death in late teens. Depression and sleep are interconnected, since depression affects sleep, vice versa. Clinical depression with symptoms of sleep disturbance were interviewed by a board certified psychiatrist following depression inventory. Age, sex matched adolescents were also accessed by depression inventory scales. Methods 71 adolescence aged from 16-18 (M:F=1:1) who visited sleep disorders clinic for their complaints of daytime sleepiness, sleep initiation problems, snoring, frequent midnight awakenings. 29% of them diagnosed with narcolepsy, 21% delayed sleep phase syndrome, 19% obstructive sleep apnea syndrome, 15% of them had chronic insomnia. Some of them have multiple sleep disorders associated diagnosis like OSA + narcolepsy, OSA + insomnia, or DSPS + OSA. 21 aged, sex matched high school students were evaluated for their anxiety and depression symptoms. Results Patients with sleep complaints had higher level of emotional distress compared with healthy adolescents without sleep complaints. Among sleep disorders, patients with narcolepsy had higher level of depression. These explains why children or adolescents with narcolepsy are initially misdiagnosed with depression in clinical setting. Comorbid depression and narcolepsy should be differentiated in clinical field. Conclusion In adolescents, patients with sleep disorders especially with narcolepsy have higher level of depression. Misdiagnosis of narcolepsy as depression may delay narcolepsy diagnosis. Support (if any)
Journal Article
Two-dimensional Bose-Einstein condensate under pressure
by
Park, Jeong-Hyuck
,
Kim, Sang-Woo
,
Cho, Wonyoung
in
Absolute zero
,
Bose-Einstein condensates
,
Condensing
2015
Evading the Mermin-Wagner-Hohenberg no-go theorem and revisiting with rigor the ideal Bose gas confined in a square box, we explore a discrete phase transition in two spatial dimensions. Through both analytic and numerical methods, we verify that thermodynamic instability emerges if the number of particles is sufficiently yet finitely large: specifically, . The instability implies that the isobar of the gas zigzags on the temperature-volume plane, featuring supercooling and superheating phenomena. The Bose-Einstein condensation can then persist from absolute zero to the superheating temperature. Without necessarily taking the large N limit, under a constant pressure condition, the condensation takes place discretely both in the momentum and in the position spaces. Our result is applicable to a harmonic trap. We assert that experimentally observed Bose-Einstein condensations of harmonically trapped atomic gases are a first-order phase transition that involves a discrete change of the density at the center of the trap.
Journal Article
National Trends in Physical Activity Among Adults in South Korea Before and During the COVID-19 Pandemic, 2009-2021
2023
There is a lack of comprehensive data on the association of the COVID-19 pandemic with the prevalence of physical activity in large-scale data sets.
To investigate long-term trends in physical activity using information from a nationally representative survey covering 2009 to 2021.
This general population-based and repeated cross-sectional study was conducted from 2009 to 2021 using the Korea Community Health Survey, a nationally representative survey in South Korea. Data from 2009 to 2021 for 2 748 585 Korean adults were obtained through a nationwide, large-scale, serial study. Data were analyzed from December 2022 through January 2023.
COVID-19 pandemic onset.
The trend of sufficient aerobic physical activity was measured by prevalence and mean metabolic equivalent of task (MET) score based on World Health Organization physical activity guidelines and defined as 600 MET-min/wk or greater. The cross-sectional survey included age, sex, body mass index (BMI), region of residence, education level, income level, smoking status, alcohol consumption level, stress status, physical activity level, and history of diabetes, hypertension, and depression.
Among 2 748 585 Korean adults (738 934 aged 50-64 years [29.1%] and 657 560 aged ≥65 years [25.9%]; 1 178 869 males [46.4%]), the prevalence of sufficient physical activity did not change significantly during the prepandemic period (β difference, 1.0; 95% CI, 0.6 to 1.4). During the pandemic, the prevalence of sufficient physical activity decreased significantly, from 36.0% (95% CI, 35.9% to 36.1%) in 2017 to 2019 to 30.0% (95% CI, 29.8% to 30.2%) in 2020 and 29.7% (95% CI, 29.5% to 29.9%) in 2021. Trends showed decreases in the prevalence of sufficient physical activity among older adults (ages ≥65 years; β difference, -16.4; 95% CI, -17.5 to -15.3) and younger adults (ages 19 to 29 years; β difference, -16.6; 95% CI, -18.1 to -15.0) during the pandemic. In particular, the trend of sufficient physical activity declined during the pandemic in females (β difference, -16.8; 95% CI, -17.6 to -16.0), individuals in urban residences (β difference, -21.2; 95% CI, -22.2 to -20.2), healthy participants (eg, those with normal BMI, 18.5 to 22.9: β difference,-12.5; 95% CI, -13.4 to -11.7), and individuals at increased risk of stress (eg, history of a depressive episode; β difference, -13.7; 95% CI, -19.1 to -8.4). Prevalence trends in mean MET score were similar to those in the main results; total mean MET score decreased from the 2017 to 2019 period (1579.1 MET-min/wk; 95% CI, 1567.5 to 1590.7 MET-min/wk) to the 2020 to 2021 period (1191.9 MET-min/wk; 95% CI, 1182.4 to 1201.4 MET-min/wk.
This cross-sectional study found that the national prevalence of physical activity was stable or consistent before the pandemic period, with a marked decrease during the pandemic, particularly among healthy individuals and subgroups at increased risk of negative outcomes, including older adults, females, urban residents, and those with depressive episodes. Future studies may be needed to evaluate the association between the COVID-19 pandemic and changes in physical activity.
Journal Article
Viral load dynamics and shedding kinetics of mpox infection: a systematic review and meta-analysis
by
Smith, Lee
,
Kwon, Rosie
,
Rahmati, Masoud
in
Anorectal
,
HIV Infections
,
Human immunodeficiency virus
2023
Abstract
Background
Viral load dynamics and shedding kinetics are critical factors for studying infectious diseases. However, evidence on the viral dynamics of mpox remains limited and inconclusive. Thus, we aimed to provide a comprehensive understanding of the viral load and viability of the re-emerged mpox virus since 2022.
Methods
For this systematic review and meta-analysis, we searched PubMed/MEDLINE, Embase and Google Scholar for published articles that are related to mpox viral dynamics up to April 2023.
Results
From 19 studies, 880 samples and 1477 specimens were collected. The pooled median Ct values appeared in the following order: skin lesion [Ct value 21.7 (IQR 17.8–25.5)], anorectal [22.3 (16.9–27.6)], saliva [25.9 (22.5–31.1)], oral [29.0 (24.5–32.8)], semen [29.6 (25.9–33.4)], urine [30.5 (24.6–36.4)], pharyngeal [31.9 (26.5–37.3)], urethra [33.0 (28.0–35.0)] and blood [33.2 (30.4–36.1)]. People living with human immunodeficiency virus (HIV) have a lower Ct value in the skin [skin HIV+, 19.2 (18.3–20.0) vs skin HIV−, 25.4 (21.2–29.0)]. From the Ct values and test day since symptom onset, we identified temporal trends of viral load for each specimen type. Changes in the trend were observed at 4 days in saliva, 5 days in blood, 6 days in skin, 7 days in anorectal, urine, semen and pharyngeal and 8 days in the urethra. We determined optimal Ct cutoff values for anorectal (34.0), saliva (27.7) and urethra (33.0) specimens, where a Ct value above each cutoff suggests minimal viral viability. Using these cutoff values, we derived the duration of viable viral isolation in each specific specimen type (anorectal 19 days, saliva 14 days and urethra 14 days).
Conclusion
Skin lesion, anorectal and saliva samples contained the highest viral load. The peak viral load manifests within 4–8 days after symptom onset, and viable virus detection was presumed to cease within 14–19 days from symptom onset in anorectal, saliva and urethral samples.
Journal Article
Supersymmetric gauged double field theory: systematic derivation by virtue of twist
by
Cho, Wonyoung
,
Fernández-Melgarejo, J. J.
,
Jeon, Imtak
in
Classical and Quantum Gravitation
,
Consistency
,
Derivation
2015
A
bstract
In a completely systematic and geometric way, we derive maximal and half-maximal supersymmetric gauged double field theories in lower than ten dimensions. To this end, we apply a simple twisting ansatz to the
D
= 10 ungauged maximal and half-maximal supersymmetric double field theories constructed previously within the so-called semi-covariant formalism. The twisting ansatz may not satisfy the section condition. Nonetheless, all the features of the semi-covariant formalism, including its complete covariantizability, are still valid after the twist under alternative consistency conditions. The twist allows gaugings as supersymmetry preserving deformations of the
D
= 10 untwisted theories after Scherk-Schwarz-type dimensional reductions. The maximal supersymmetric twist requires an extra condition to ensure both the Ramond-Ramond gauge symmetry and the 32 supersymmetries unbroken.
Journal Article
National Trends in Sadness, Suicidality, and COVID-19 Pandemic–Related Risk Factors Among South Korean Adolescents From 2005 to 2021
2023
Despite the COVID-19 pandemic's effect on daily life, limited research exists on the prevalence and risk factors of suicidality and sadness among South Korean adolescents.
To examine whether the observed sadness and suicidality in the early to middle periods of the COVID-19 pandemic differed from the expected level and to investigate changes in risk factors for sadness and suicidality.
This nationwide serial cross-sectional survey study used data on 1 109 776 Korean adolescents aged 13 to 18 years from the Korea Youth Risk Behavior Web-based Survey from 2005 to 2021.
The COVID-19 pandemic.
The pattern of changes in the percentage or proportion of sadness or suicidality, as well as the risk factors for sadness or suicidality. The transitional effect of the COVID-19 pandemic was assessed using weighted odds ratios (wORs) or weighted beta coefficients with 95% CIs.
Between 2005 and 2021, 1 109 776 adolescents (mean [SD] age, 15.0 [1.7] years; 51.5% male adolescents; and 51.7% in grades 7-9 and 48.3% in grades 10-12) were included in the Korea Youth Risk Behavior Web-based Survey. The slope of the long-term trends in sadness and suicidality decreased in the prepandemic period (sadness: from 37.8% [95% CI, 37.4%-38.2%] in 2005-2007 to 26.1% [95% CI, 25.9%-26.4%] in 2016-2019; suicidality: from 23.0% [95% CI, 22.7%-23.3%] in 2005-2007 to 12.3% [95% CI, 12.1%-12.5%] in 2016-2019), whereas the slope increased during the COVID-19 pandemic (sadness: from 25.0% [95% CI, 24.5%-25.6%] in 2020 to 26.6% [95% CI, 26.1%-27.1%] in 2021; trend difference in β, 0.249 [95% CI, 0.236-0.262]; suicidality: from 10.7% [95% CI, 10.3%-11.1%] in 2020 to 12.5% [95% CI, 12.1%-12.9%] in 2021; trend difference in β, 0.328 [95% CI, 0.312-0.344]). The trends presented a similar tendency in the subgroups according to sex, school grade, residential area, smoking status, and current alcohol use. Compared with the prepandemic period, the risk factors associated with sadness during the pandemic were younger age (wOR, 0.907; 95% CI, 0.881-0.933), female sex (wOR, 1.031; 95% CI, 1.001-1.062), urban residence (wOR, 1.120; 95% CI, 1.087-1.153), current smoking status (wOR, 1.134; 95% CI, 1.059-1.216), and current alcohol use (wOR, 1.051; 95% CI, 1.002-1.102). Female sex (wOR, 1.064; 95% CI, 1.021-1.109), urban residence (wOR, 1.117; 95% CI, 1.074-1.162), and low economic status (wOR, 1.286; 95% CI, 1.180-1.403) were the risk factors significantly associated with suicidality after the COVID-19 pandemic began.
In this nationwide serial cross-sectional survey study of South Korean adolescents, the slope of the prevalence of sadness and suicidality increased during the COVID-19 pandemic after a decrease prior to the pandemic. The findings suggest that public health measures are needed to recognize vulnerable groups with risk factors and to prevent an increase in sadness and suicidality among adolescents during the COVID-19 pandemic.
Journal Article