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449 result(s) for "Kim, Seungwon"
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Soil heterotrophic and autotrophic respiration respond differently to seasonal variations in temperature and water content under monsoon continental climate
Soil respiration (R S ) comprises terrestrial ecosystems’ second-largest carbon flux. Yet, methodological errors in R S partitioning and uncertainties in seasonal responses of R S make it difficult to predict future R S . Here, we tested the assumption of R S partitioning (similar microbial respiration between planted and root-free soils), and explored two components of R S , autotrophic and heterotrophic respiration (R A , R H , respectively), in a temperate grassland under monsoon continental climate. Microbial respiration in soils from planted plots was 3.88 times higher than that from root-free plots during lab incubation. In field, R H :R S ratio was relatively low during non-monsoon, but increased during monsoon. The R H was more sensitive to temperature than R S , indicating a greater Q 10 of R H than that of estimated R A . The annual R H :R S excluding the monsoon period was comparable to those reported in the global Soil Respiration Database (SRDB) and other Korean literature. This study highlights that the assumption of R S partitioning can be violated, that R H exhibits a greater sensitivity to changes in temperature and soil water content than R A , and that annual R H :R S may be similar across the globe when extreme precipitation (e.g., monsoon) is excluded.
Spatial genetic structure of 2009 H1N1 pandemic influenza established as a result of interaction with human populations in mainland China
Identifying the spatial patterns of genetic structure of influenza A viruses is a key factor for understanding their spread and evolutionary dynamics. In this study, we used phylogenetic and Bayesian clustering analyses of genetic sequences of the A/H1N1pdm09 virus with district-level locations in mainland China to investigate the spatial genetic structure of the A/H1N1pdm09 virus across human population landscapes. Positive correlation between geographic and genetic distances indicates high degrees of genetic similarity among viruses within small geographic regions but broad-scale genetic differentiation, implying that local viral circulation was a more important driver in the formation of the spatial genetic structure of the A/H1N1pdm09 virus than even, countrywide viral mixing and gene flow. Geographic heterogeneity in the distribution of genetic subpopulations of A/H1N1pdm09 virus in mainland China indicates both local to local transmission as well as broad-range viral migration. This combination of both local and global structure suggests that both small-scale and large-scale population circulation in China is responsible for viral genetic structure. Our study provides implications for understanding the evolution and spread of A/H1N1pdm09 virus across the population landscape of mainland China, which can inform disease control strategies for future pandemics.
B cell signatures and tertiary lymphoid structures contribute to outcome in head and neck squamous cell carcinoma
Current immunotherapy paradigms aim to reinvigorate CD8 + T cells, but the contribution of humoral immunity to antitumor immunity remains understudied. Here, we demonstrate that in head and neck squamous cell carcinoma (HNSCC) caused by human papillomavirus infection (HPV + ), patients have transcriptional signatures of germinal center (GC) tumor infiltrating B cells (TIL-Bs) and spatial organization of immune cells consistent with tertiary lymphoid structures (TLS) with GCs, both of which correlate with favorable outcome. GC TIL-Bs in HPV + HNSCC are characterized by distinct waves of gene expression consistent with dark zone, light zone and a transitional state of GC B cells. Semaphorin 4a expression is enhanced on GC TIL-Bs present in TLS of HPV + HNSCC and during the differentiation of TIL-Bs. Our study suggests that therapeutics to enhance TIL-B responses in HNSCC should be prioritized in future studies to determine if they can complement current T cell mediated immunotherapies. Recent studies have highlighted the importance of B cells and tertiary lymphoid structures (TLS) in the modulation of anti-tumor immune responses. Here, the authors characterize how HPV status influences the phenotype of tumor infiltrating B cells in patients with head and neck squamous cell carcinoma and demonstrate that TLS with germinal centres are associated with better survival.
Investigating immune and non-immune cell interactions in head and neck tumors by single-cell RNA sequencing
Head and neck squamous cell carcinoma (HNSCC) is characterized by complex relations between stromal, epithelial, and immune cells within the tumor microenvironment (TME). To enable the development of more efficacious therapies, we aim to study the heterogeneity, signatures of unique cell populations, and cell-cell interactions of non-immune and immune cell populations in 6 human papillomavirus (HPV) + and 12 HPV – HNSCC patient tumor and matched peripheral blood specimens using single-cell RNA sequencing. Using this dataset of 134,606 cells, we show cell type-specific signatures associated with inflammation and HPV status, describe the negative prognostic value of fibroblasts with elastic differentiation specifically in the HPV + TME, predict therapeutically targetable checkpoint receptor-ligand interactions, and show that tumor-associated macrophages are dominant contributors of PD-L1 and other immune checkpoint ligands in the TME. We present a comprehensive single-cell view of cell-intrinsic mechanisms and cell-cell communication shaping the HNSCC microenvironment. The tumor microenvironment (TME) has an important role in Head and Neck Squamous Cell Carcinoma (HNSCC) progression. Here, using single-cell RNA sequencing and multiplexed imaging, the authors report the cellular complexity of the TME in patients with HNSCC, exploring inflammatory status, stromal heterogeneity and immune checkpoint receptor-ligand interactions.
A Review on the Performance of Fibers on Restrained Plastic Shrinkage Cracks
Multiple studies have investigated the use of steel, synthetic fibers, and natural fibers to reduce plastic shrinkage cracks in concrete, which are mostly caused by water evaporation from the surface of the material. This review used original published research articles from the Web of Science and Scopus database to evaluate the performance and relationship between the fiber volume, aspect ratio, compressive strength, and plastic shrinkage cracking. This review also discussed the most widely used technique for evaluating plastic shrinkage cracking, the ASTM C 1579, with two bottom restraints and a central stress riser to induce cracking, and its modified version with additional reinforcement for further restraining the ASTM C 1579 mold. Longer fibers function better than shorter fibers because of their larger surface area, which allows them to bridge fissures. It was also observed that crack initiation time is delayed when fibers are added to concrete. In addition, as the volume proportion of the fibers increased, the plastic shrinkage cracks decreased, but the compressive strength declined. Furthermore, the volume fraction of the fibers had a greater effect on reducing cracking than the aspect ratio. It was also concluded that a fiber volume inclusion below 1% is best.
Depth Segmentation Approach for Egocentric 3D Human Pose Estimation with a Fisheye Camera
In this paper, we propose a novel approach for egocentric 3D human pose estimation using fisheye images captured by a head-mounted display (HMD). Most studies on 3D pose estimation focused on heatmap regression and lifting 2D information to 3D space. This paper addresses the issue of depth ambiguity with highly distorted 2D fisheye images by proposing the SegDepth module, which jointly regresses segmentation and depth maps from the image. The SegDepth module distinguishes the human silhouette, which is directly related to pose estimation through segmentation, and simultaneously estimates depth to resolve the depth ambiguity. The extracted segmentation and depth information are transformed into embeddings and used for 3D joint estimation. In the evaluation, the SegDepth module improves the performance of existing methods, demonstrating its effectiveness and general applicability in improving 3D pose estimation. This suggests that the SegDepth module can be integrated into well-established methods such as Mo2Cap2 and xR-EgoPose to improve 3D pose estimation and provide a general performance improvement.
Behavior of Barrier Wall under Hydrogen Storage Tank Explosion with Simulation and TNT Equivalent Weight Method
Hydrogen gas storage place has been increasing daily because of its consumption. Hydrogen gas is a dream fuel of the future with many social, economic and environmental benefits to its credit. However, many hydrogen storage tanks exploded accidentally and significantly lost the economy, infrastructure, and living beings. In this study, a protection wall under a worst-case scenario explosion of a hydrogen gas tank was analyzed with commercial software LS-DYNA. TNT equivalent method was used to calculate the weight of TNT for Hydrogen. Reinforced concrete and composite protection wall under TNT explosion was analyzed with a different distance of TNT. The initial dimension of the reinforced concrete protection wall was taken from the Korea gas safety code book (KGS FP217) and studied the various condition. H-beam was used to make the composite protection wall. Arbitrary-Lagrangian-Eulerian (ALE) simulation from LS-DYNA and ConWep pressure had a good agreement. Used of the composite structure had a minimum displacement than a normal reinforced concrete protection wall. During the worst-case scenario explosion of a hydrogen gas 300 kg storage tank, the minimum distance between the hydrogen gas tank storage and protection wall should be 3.6 m.
Bond Properties of Glass-Fiber-Reinforced Polymer Hybrid Rebar in Reinforced Concrete with Respect to Bond Length
Preventing rebar corrosion in reinforced concrete (RC) structures has been actively researched worldwide. One of the most powerful solutions is the use of fiber-reinforced polymer (FRP) rebars. However, there are limitations in the mechanical design and construction of FRP rebars because their tensile characteristics are extremely different from those of conventional rebars and they have a different modulus of elasticity. FRP rebars are relatively cost-efficient when fabricated with glass fibers, but they are still costly compared to conventional rebars. Therefore, hybrid rebars fabricated by covering conventional rebars with glass FRP (GFRP) materials were developed in this study. GFRP hybrid rebars have increased durability in marine environments while maintaining the same mechanical properties as conventional rebars. As the difference in rebar diameter of the bonded area decreased, the tensile strength of the concrete increased. As a result, pull-out failure or tensile failure caused by the yielding of the rebars occurred in small-diameter rebars. The experimental results showed that the maximum load for the D13 deformed steel bar was 52.2 kN at a bond length of 50 mm and 76.1 kN at 100 mm, while for the D19 deformed steel bar, it was 65.3 kN at 50 mm and 103.7 kN at 100 mm. The bond properties of hybrid GFRB rebars were found to be lower than those of deformed steel bars. These properties were improved greatly by increasing the thickness of the GFRP materials on the surface of the deformed steel bars, highlighting a path toward high-performance, corrosion-resistant concrete.
Mitigation of Restrained Plastic Shrinkage Cracks in Concrete: A Systematic Review on the Role of Chemical Admixtures
Plastic shrinkage cracks are a major concern in concrete structures, arising from rapid moisture loss before the development of adequate tensile strength. These cracks compromise durability, increase permeability, and accelerate structural deterioration. Effective mitigation strategies are therefore essential to improve concrete performance and serviceability. This study examined the mechanisms and performance of various admixtures, including shrinkage‐reducing admixtures (SRAs), superplasticizers (SPs), accelerators (ACCs), and retarders (RETs), to mitigate plastic shrinkage cracks. The preferred reporting items for systematic reviews and meta‐analyses (PRISMA) framework was utilized to select peer‐reviewed articles from Web of Science (WOS), ensuring a comprehensive evaluation of their mechanisms and effectiveness. The findings indicate that SRAs reduce surface tension, lowering capillary pressure and evaporation rates. ACCs accelerate hydration, minimizing the period of vulnerability to shrinkage, while RETs delay setting, allowing longer moisture retention. SPs improve workability, reducing settlement‐induced cracking. One‐way analysis of variance (ANOVA) indicated statistical significance ( p < 0.05) for the variation in crack reduction ratio (CRR) among admixture groups. The box plot and Tukey HSD analysis indicated that SRAs exhibited superior performance, followed by SPs, RETs, and ACCs. Pearson’s and Spearman’s correlation coefficients, together with regression analysis, indicated that SRAs exhibited superior performance in humid and windy conditions, but inferior performance at elevated temperatures. SPs showed superior performance in humid and elevated temperature conditions but diminished efficacy in windy situations. ACCs perform adequately in elevated temperatures but are less effective in windy conditions. RETs demonstrated optimal performance in humid conditions and a fair performance at elevated temperatures but demonstrated worse efficacy in windy situations.
Pretreatment pain predicts perineural invasion in patients with head and neck squamous cell carcinoma
Objectives Perineural invasion (PNI) in head and neck cancer (HNC) is a distinct pathological feature used to indicate aggressive tumor behavior and drive treatment strategies. Our study examined the prevalence and predictors of PNI in HNC patients stratified by tumor site. Study design and methods A retrospective analysis of head and neck squamous cell carcinoma (HNSCC) patients who underwent surgical resection at the University of Pittsburgh Medical Center between 2015 and 2018 was performed. Pretreatment pain was assessed at least 1 week before surgery using the Functional Assessment of Cancer Therapy-Head and Neck (FACT-H&N). Demographics, clinical characteristics, and concomitant medications were obtained from medical records. Patients with cancers at the oropharynx and non-oropharynx (i.e., cancer at oral cavity, mandible, larynx) sites were separately analyzed. Tumor blocks were obtained from 10 patients for histological evaluation of intertumoral nerve presence. Results A total of 292 patients (202 males, median age = 60.94 ± 11.06) were assessed. Pain and PNI were significantly associated with higher T stage ( p < 0.001) and tumor site ( p < 0.001); patients with non-oropharynx tumors reported more pain and had a higher incidence of PNI compared to oropharynx tumors. However, multivariable analysis identified pain as a significant variable uniquely associated with PNI for both tumor sites. Evaluation of nerve presence in tumor tissue showed 5-fold higher nerve density in T2 oral cavity tumors compared to oropharyngeal tumors. Conclusions Our study finds that PNI is associated with pretreatment pain and tumor stage. These data support the need for additional research into the impact of tumor location when investigating targeted therapies of tumor regression.