25 results on '"Khurelbaatar T"'
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2. Spatial variability of near-surface ground temperatures in a discontinuous permafrost area in Mongolia
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Khurelbaatar Temuujin, Avirmed Dashtseren, Bernd Etzelmüller, Tsogtbaatar Undrakhtsetseg, Kristoffer Aalstad, and Sebastian Westermann
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permafrost ,ground surface temperature ,snow cover ,topography ,vegetation ,remote sensing ,Science - Abstract
In Central Asia, the ground thermal regime is strongly affected by the interplay between topographic factors and ecosystem properties. In this study, we investigate the governing factors of the ground thermal regime in an area in Central Mongolia, which features discontinuous permafrost and is characterized by grassland and forest ecosystems. Miniature temperature dataloggers were used to measure near-surface temperatures at c. 100 locations throughout the 6 km2 large study area, with the goal to obtain a sample of sites that can represent the variability of different topographic and ecosystem properties. Mean annual near-surface ground temperatures showed a strong variability, with differences of up to 8 K. The coldest sites were all located in forests on north-facing slopes, while the warmest sites are located on steep south-facing slopes with sparse steppe vegetation. Sites in forests show generally colder near-surface temperatures in spring, summer and fall compared to grassland sites, but they are warmer during the winter season. The altitude of the measurement sites did not play a significant role in determining the near-surface temperatures, while especially solar radiation was highly correlated. In addition, we investigated the suitability of different hyperspectral indices calculated from Sentinel-2 as predictors for annual average near-surface ground temperatures. We found that especially indices sensitive to vegetation properties, such as the Normalized Difference Vegetation Index (NDVI), show a strong correlation. The presented observations provide baseline data on the spatiotemporal patterns of the ground thermal regime which can be used to train or validate modelling and remote sensing approaches targeting the impacts of climate change.
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- 2024
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3. Glacial Lakes of Mongolia
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Michael Walther, Ulrich Kamp, Nyam-Osor Nandintsetseg, Avirmed Dashtseren, and Khurelbaatar Temujin
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glacial lake ,ice-contact lake ,moraine-dammed lake ,Mongolia ,Zungenbecken lake ,Geography (General) ,G1-922 - Abstract
The over 2200 lakes of Mongolia are generally poorly studied, particularly the glacial lakes. This overview study presents a classification of the glacial lakes based on tectonic-geological and geomorphological dynamics. Selected representative lakes are described using results from fieldwork and satellite image analysis, including bathymetry, paleoshorelines, and recent lake-level fluctuations between 1987 and 2020. Generally, lake levels dropped from the early Holocene until recently, with the onset of the climate change-driven glacier recession that has resulted in lake-level rises and area expansion in almost all moraine-dammed, tongue-basin, and ice-contact lakes. In contrast, endorheic lakes have mainly been shrinking for the past forty years because of an increase in air temperature and evaporation rates and the effects of an intensifying water use within the catchment for irrigation, mining, and hydroelectric energy production in the form of dams. The creation of a lake monitoring system based on an in-depth inventory is recommended.
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- 2024
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4. Spatial and Temporal Variations of Freezing and Thawing Indices From 1960 to 2020 in Mongolia
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Avirmed Dashtseren, Khurelbaatar Temuujin, Sebastian Westermann, Altangerel Batbold, Yondon Amarbayasgalan, and Dorjgotov Battogtokh
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freezing index ,thawing index ,transition zones ,climate warming ,Mongolia ,Science - Abstract
Mongolia is one of the most sensitive regions to climate change, located in the transition of several natural and permafrost zones. Long-term trends in air freezing and thawing indices can therefore enhance our understanding of climate change. This study focuses on changes of the spatiotemporal patterns in air freezing and thawing indices over Mongolia from 1960 to 2020, using observations at 30 meteorological stations. Our results shows that the freezing index ranges from −945.5 to −4,793.6°C day, while the thawing index ranges from 1,164.4 to 4,021.3°C day over Mongolia, and their spatial patterns clearly link to the latitude and altitude. During the study period, the trend in the thawing index (14.4°C-day per year) was larger than the trend in the freezing index (up to −10.1°C-day per year), which results in the net increase of air temperature by 2.4°C across Mongolia. Overall, the increase in the thawing index was larger in the low latitudes and altitudes (e.g., the Gobi-desert, steppes, the Great lake depression and major river valleys) than in high latitudes and altitudes (mountain regions), while it was the opposite for the freezing index. The highest values for both thawing index and freezing index (i.e. the least negative values) have occurred during the last 2 decades. As the trends in the freezing and thawing indices and mean annual air temperature confirm intensive climate warming, increased permafrost degradation and shallower seasonally frozen ground are expected throughout Mongolia.
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- 2021
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5. Glaciers, Permafrost and Lake Levels at the Tsengel Khairkhan Massif, Mongolian Altai, During the Late Pleistocene and Holocene
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Michael Walther, Avirmed Dashtseren, Ulrich Kamp, Khurelbaatar Temujin, Franz Meixner, Caleb G. Pan, and Yadamsuren Gansukh
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environmental change ,climate ,glacier ,Holocene ,lake ,Mongolian Altai ,permafrost ,Pleistocene ,Geology ,QE1-996.5 - Abstract
Understanding paleo—and recent environmental changes and the dynamics of individual drivers of water availability is essential for water resources management in the Mongolian Altai. Here, we follow a holistic approach to uncover changes in glaciers, permafrost, lake levels and climate at the Tsengel Khairkhan massif. Our general approach to describe glacier and lake level changes is to combine traditional geomorphological field mapping with bathymetric measurements, satellite imagery interpretation, and GIS analyses. We also analysed climate data from two nearby stations, and measured permafrost temperature conditions at five boreholes located at different elevations. We identified four glacial moraine systems (M4-M1) and attribute them to the period from the penultimate glaciation (MIS 4/5) until the Little Ice Age (MIS 1). During the Local Last Glacial Maximum (LLGM; MIS 2), a glacier reached down into the western Kharganat Valley and blocked it, resulting in the formation of the endorheic Khar Lake basin. Subsequently, the lake was fed mainly by precipitation and permafrost meltwater. In recent years, glaciers have been in strong recession, yet Khar Lake levels have remained relatively stable, which is in contrast to mainly decreasing lake levels in other regions throughout Mongolia. While temperatures in the Altai are increasing (leading to increasing evaporation), precipitation in higher elevations has increased, which—in addition to increased glacier and permafrost melting—would counteract the increasing aridity effects. A systematic and holistic monitoring of glaciers, permafrost, lake levels and climate in the Mongolian Altai is necessary, and results from (sub-)disciplines need to be correlated.
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- 2017
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6. In vitro biomechanics of divot use, and their placement, in orthodontic aligner therapy.
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Kaur H, Khurelbaatar T, Mah J, Heo G, Major PW, and Romanyk DL
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- Biomechanical Phenomena, Humans, In Vitro Techniques, Dental Stress Analysis, Orthodontic Appliance Design, Maxilla, Stress, Mechanical, Tooth Movement Techniques instrumentation, Incisor
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Introduction: To evaluate biomechanics of an aligner utilizing divots and the effect of their vertical placement on the right maxillary central incisor., Methods: An in vitro Orthodontic SIMulator (OSIM) was used to test forces and moments generated by aligners incorporating divots. The OSIM arch was scanned to generate a. STL version that was modified to create four models by placing divots on different positions of the right central maxillary incisor: GI - divots on gingival-third of lingual surface and incisal-third of labial surface; GM - divots on gingival-third of lingual surface and middle-third of labial surface; MI - divots on middle-third of lingual surface and incisal-third of labial surface; MM - divots on middle-third of lingual surface and middle-third of labial surface. Aligners (n = 30/model) were fabricated using a 0.75 mm thick polyethylene terephthalate material and Biostar® machine following the manufacturer's recommendations. A one-way MANOVA followed by one-way ANOVA (α = 0.05) was utilized to test effect of models on buccolingual force (Fy) and mesiodistal moment (Mx) at 0.20 mm of lingual displacement of the right maxillary central incisor., Results: Mean Mx for GI (-5.68 ± 7.38 Nmm), GM (3.75 ± 5.54 Nmm), MI (-4.27 ± 1.48 Nmm) and MM (1.96 ± 0.99 Nmm) models showed statistical differences between GI and GM, GI and MM, GM and MI and MI and MM. GI exerted the largest Fy (1.87 ± 0.75 N) followed by GM (1.10 ± 0.47 N), MI (0.70 ± 0.23 N) and MM (0.28 ± 0.08 N) with significant differences between GI and GM, GI and MI, GI and MM and GM and MM models., Conclusions: Vertical divot placement on a right central incisor had a significant effect on aligner biomechanics. Buccolingual forces exerted by models GI, GM and MI were within the range suggested by literature for bodily tooth movement without major root tipping for GM and MI models., (© 2024 The Authors. Orthodontics & Craniofacial Research published by John Wiley & Sons Ltd.)
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- 2024
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7. The Emerging Leaders Committee: Turning a new page for APAGE to nurture the next generation of Asia-Pacific leaders in digestive health.
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Lui RN, Chan TT, Chantarojanasiri T, Chien MM, Dao VH, Devi J, Huang DQ, Jin EH, Khurelbaatar T, Nabi Z, Otani K, Panlilio MTT, Park SH, Pribadi RR, Qiao Y, Siah K, Sonthalia N, Tran QT, Xiao Y, and Raja Ali RA
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- Humans, Asia, Societies, Medical, Leadership, Gastroenterology organization & administration
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- 2024
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8. Strong-field photoelectron holography in the subcycle limit.
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Khurelbaatar T, Heo J, Yu S, Lai X, Liu X, and Kim DE
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Strong-field photoelectron holography is promising for the study of electron dynamics and structure in atoms and molecules, with superior spatiotemporal resolution compared to conventional electron and X-ray diffractometry. However, the application of strong-field photoelectron holography has been hindered by inter-cycle interference from multicycle fields. Here, we address this challenge by employing a near-single-cycle field to suppress the inter-cycle interference. We observed and separated two distinct holographic patterns for the first time. Our measurements allow us not only to identify the Gouy phase effect on electron wavepackets and holographic patterns but also to correctly extract the internuclear separation of the target molecule from the holographic pattern. Our work leads to a leap jump from theory to application in the field of strong-field photoelectron holography-based ultrafast imaging of molecular structures., (© 2024. The Author(s).)
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- 2024
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9. Near- and far-field study of polarization-dependent surface plasmon resonance in bowtie nano-aperture arrays.
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Choi S, Park J, Chew SH, Khurelbaatar T, Gliserin A, Kim S, and Kim DE
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Bowtie nano-apertures can confine light into deep subwavelength volumes with extreme field enhancement, making them a useful tool for various applications such as optical trapping, deep subwavelength imaging, nanolithography, and sensors. However, the correlation between the near- and far-field properties of bowtie nano-aperture arrays has yet to be fully explored. In this study, we experimentally investigated the polarization-dependent surface plasmon resonance in bowtie nano-aperture arrays using both optical transmission spectroscopy and photoemission electron microscopy. The experimental results reveal a nonlinear redshift in the transmission spectra as the gap size of the bowtie nanoaperture decreases for vertically polarized light, while the transmission spectra remain unchanged with different gap sizes for horizontally polarized light. To elucidate the underlying mechanisms, we present simulated charge and current distributions, revealing how the electrons respond to light and generate the plasmonic fields. These near-field distributions were verified by photoemission electron microscopy. This study provides a comprehensive understanding of the plasmonic properties of bowtie nano-aperture, enabling their further applications, one of which is the optical switching of the resonance wavelength in the widely used visible spectral region without changing the geometry of the nanostructure.
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- 2023
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10. Three-dimensional morphometric analysis of cranial sutures - A novel approach to quantitative analysis.
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Remesz R, Khurelbaatar T, Rabey KN, Doschak MR, and Romanyk DL
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Objective: Differences in complexity of cranial suture forms on the endocranial (i.e., deep) and ectocranial (i.e., superficial) skull surfaces have been noted in the literature, indicating through thickness three-dimensional (3D) suture variability depending on the chosen section and necessity for considering the complete 3D structure in many cases. This study aims to evaluate the variability of suture morphology through the skull thickness using a rat model, and to provide more robust metrics and methodologies to analyze suture morphology., Design: X-ray micro-computed tomographic (μCT) imaging methods were utilized in order to provide internal structure information. Methods were developed to isolate and analyze sutures widths and linear interdigitation index (LII) values on each adjacent offset transverse plane of the μCT datasets. LII was defined as the curved path length of the suture divided by the linear length between the ends of the region of interest. Scans were obtained on 15 female rats at ages of 16, 20, and 24 weeks ( n = 5/age). Samples were imaged at 18 μm resolutions with 90 kV source voltage, 278 μA source amperage, and 0.7° increments. Suture widths and LII values were compared using a Kruskal-Wallis test., Results: 3D variability in local suture widths within individuals, as well as through thickness variabilities in planar widths and LII was observed. Kruskal-Wallis tests for bulk through thickness averaged suture widths and LII were found to be statistically insignificant, despite clear geometric differences through suture thicknesses., Conclusion: Although the bulk morphometric variability between age groups was found to be statistically insignificant, the 3D variability within individuals point to the importance of analyzing suture form using 3D metrics when studying suture development, response to functional activity, or morphometry in general., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)
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- 2023
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11. Maintenance of complete mucosal healing is associated with avoiding restenosis after endoscopic balloon dilation of Crohn's disease-related small intestinal strictures.
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Dashnyam U, Nagayama M, Yano T, Sakamoto H, Mieno M, Owada J, Oguro K, Khurelbaatar T, Sunada K, Lefor AK, and Yamamoto H
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Background: Endoscopic balloon dilation (EBD) is an effective, minimally invasive treatment for Crohn's disease (CD) related intestinal strictures. However, restenosis frequently occurs and requires repetitive EBD or surgical resection. Since previous studies could not evaluate restenosis based on stricture diameter, factors affecting restenosis after EBD were unclear. This study aimed to identify these factors by precisely measuring the diameter of small intestinal strictures in patients with CD., Methods: This single-center retrospective study enrolled patients with CD with de novo small intestinal strictures who underwent two double-balloon enteroscopy sessions (EBD and follow-up) between January 2016 and October 2021. Clinical and endoscopic data were obtained from electronic medical records. A calibrated small-caliber-tip transparent hood was used to precisely measure stricture diameters. Multivariate analysis was performed to identify factors associated with restenosis., Results: Forty-eight patients (37 male) were analyzed. The total number of strictures detected decreased from 162 to 143. The mean diameter of all strictures and the narrowest stricture in each patient increased significantly from 8.6 to 9.8 mm and from 7.6 to 8.7 mm, respectively. Thirty-two (67%) patients developed endoscopic restenosis. Multivariate analysis showed that the presence of ulcers at the follow-up session was a risk factor for restenosis (odds ratio 9.4, p = 0.01). Patients with complete mucosal healing at both sessions ( n = 21) showed significant improvement in the narrowest stricture (+1.7 mm, p = 0.001)., Conclusions: Maintenance of complete mucosal healing is significantly associated with avoiding restenosis after EBD in CD-related small intestinal strictures., Competing Interests: Hironori Yamamoto has patents for the calibrated small‐caliber‐tip transparent hood. Hironori Yamamoto has patents for double‐balloon endoscopy and a consultant relationship with Fujifilm. Tomonori Yano and Hirotsugu Sakamoto have received research funding and honoraria from Fujifilm. No other authors have personal financial relationships with a commercial entity producing healthcare‐related products and/or services relevant to this article., (© 2023 The Authors. DEN Open published by John Wiley & Sons Australia, Ltd on behalf of Japan Gastroenterological Endoscopy Society.)
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- 2023
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12. Investigating the role of aligner material and tooth position on orthodontic aligner biomechanics.
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Kaur H, Khurelbaatar T, Mah J, Heo G, Major PW, and Romanyk DL
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- Biomechanical Phenomena, Polyethylene Terephthalates, Bicuspid, Polyethylene Glycols, Orthodontic Appliance Design, Tooth Movement Techniques methods
- Abstract
The primary objective of this work was to investigate the effect of material selection and tooth position on orthodontic aligner biomechanics. Additionally, material property changes with thermoforming were studied to elucidate its role in material performance in-vitro. An orthodontic simulator (OSIM) was used to evaluate forces and moments at 0.20 mm of lingual displacement for central incisor, canine and second premolar using Polyethylene terephthalate (PET), Polyurethane (PU) and Glycol-modified polyethylene terephthalate (PET-G) materials. The OSIM was scanned to generate a model used to fabricate aligners using manufacturer-specified thermoforming procedures. Repeated measures of MANOVA was used to analyze the effect of teeth and material on forces/moments. The role of thermoforming was evaluated by flexural modulus estimated by 3-point bend tests. Pre-thermoformed and post-thermoformed samples were prepared using as-received sheets and those thermoformed over a simplified arch using rectangular geometry, respectively. Groups were compared using Two-way ANOVA. The PET, PU, and PET-G materials exerted maximum buccal force and corresponding moments on the canine. PU exerted more buccal force than PET-G on the canine and second premolar, and more than PET on the second premolar. The impact of thermoforming varied according to the specific polymer: PET-G remained stable, there was a slight change for PET, and a significant increase was noted for PU from pre-thermoformed to post-thermoforming. The results of this study elucidate the influence of material and arch position on the exerted forces and moments. Further, the mechanical properties of thermoplastic materials should be evaluated after thermoforming to characterize their properties for clinical application., (© 2022 Wiley Periodicals LLC.)
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- 2023
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13. Linked color imaging improves identification of early gastric cancer lesions by expert and non-expert endoscopists.
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Fockens K, de Groof J, van der Putten J, Khurelbaatar T, Fukuda H, Takezawa T, Miura Y, Osawa H, Yamamoto H, and Bergman J
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- Humans, Image Enhancement methods, Early Detection of Cancer methods, Narrow Band Imaging methods, Endoscopy, Stomach Neoplasms diagnostic imaging, Stomach Neoplasms pathology
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Background and Aims: Early gastric cancer (EGC) lesions are often subtle and endoscopically poorly visible. The aim of this study is to evaluate the additive effect of linked color imaging (LCI) next to white-light endoscopy (WLE) for identification of EGC, when assessed by expert and non-expert endoscopists., Methods: Forty EGC cases were visualized in corresponding WLE and LCI images. Endoscopists evaluated the cases in 3 assessment phases: Phase 1: WLE images only; Phase 2: LCI images only; Phase 3: WLE and LCI images side-to-side. First, 3 expert endoscopists delineated all cases. A high level of agreement between the expert delineations corresponded with a high AND/OR ratio. Subsequently, 62 non-experts indicated their preferred biopsy location. Outcomes of the study are as follows: (1) difference in expert AND/OR ratio; (2) accuracy of biopsy placement by non-expert endoscopists; and (3) preference of imaging modality by non-expert endoscopists., Results: Quantitative agreement between experts increased significantly when LCI was available (0.58 vs. 0.46, p = 0.007). This increase was more apparent for the more challenging cases (0.21 vs. 0.47, p < 0.001). Non-experts placed the biopsy mark more accurately with LCI (82.3% vs. 87.2%, p < 0.001). Again this increase was more profound for the more challenging cases (70.4% vs. 83.4%, p < 0.001). Non-experts indicated to prefer LCI over WLE., Conclusion: The addition of LCI next to WLE improves visualization of EGC. Experts reach higher consensus on discrimination between neoplasia and inflammation when using LCI. Non-experts improve their targeted biopsy placement with the use of LCI. LCI therefore appears to be a useful tool for identification of EGC., (© 2022. The Author(s).)
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- 2022
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14. Electrolyte-free gel immersion endoscopic submucosal dissection of gastric lesions.
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Khurelbaatar T, Miura Y, Yano T, Iwashita C, Takahashi H, Lefor AK, Osawa H, and Yamamoto H
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- Gastric Mucosa pathology, Gastric Mucosa surgery, Gastroscopy, Humans, Immersion, Endoscopic Mucosal Resection, Stomach Diseases, Stomach Neoplasms pathology, Stomach Neoplasms surgery
- Abstract
Competing Interests: Hironori Yamamoto has patents for ESD devices and double-balloon endoscopy produced by Fujifilm Corp. He is also a consultant and has received honoraria, grants, and royalties from Fujifilm Corp. Hiroyuki Osawa has received honoraria and grants from Fujifilm Corp. Tomonori Yano has patents for the dedicated electrolyte-free gel. Yoshimasa Miura and Tomonori Yano have received honoraria from Fujifilm Corp. The remaining authors declare that they have no conflict of interest.
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- 2022
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15. Cranial suture morphometry and mechanical response to loading: 2D vs. 3D assumptions and characterization.
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Remesz R, Khurelbaatar T, Grotski M, Popowics T, Rafferty K, Herring SW, Addison O, Doschak MR, and Romanyk DL
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- Animals, Cross-Sectional Studies, Head, Sutures, Swine, Cranial Sutures diagnostic imaging, Skull diagnostic imaging, Skull physiology
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Cranial sutures are complex soft tissue structures whose mechanics are often studied due to their link with bone growth in the skull. Researchers will often use a cross-sectional two-dimensional slice to define suture geometry when studying morphometry and/or mechanical response to loading. However, using a single cross section neglects the full suture complexity and may introduce significant errors when defining their form. This study aims to determine trends in suture path variability through skull thickness in a swine model and the implications of using a 'representative' cross section on mechanical modeling. To explore these questions, a mixture of quantitative analysis of computed tomography images and finite element models was used. The linear interdigitation and width of coronal and sagittal sutures were analyzed on offset transverse planes through the skull thickness. It was found that sagittal suture width and interdigitation were largely consistent through the skull thickness, whereas the coronal suture showed significant variation in both. The finite element study found that average values of displacement and strain were similar between the two-dimensionally variable and three-dimensionally variable models. Larger ranges and more complex distributions of strain were found in the three-dimensionally variable model. Outcomes of this study indicate that the appropriateness of using a representative cross section to describe suture morphometry and predict mechanical response should depend on specific research questions and goals. Two-dimensional approximations can be sufficient for less-interdigitated sutures and when bulk site mechanics are of interest, while taking the true three-dimensional geometry into account is necessary when considering spatial variability and local mechanical response., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
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- 2022
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16. Usefulness of linked color imaging for the detection of obscure early gastric cancer: Multivariate analysis of 508 lesions.
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Khurelbaatar T, Miura Y, Osawa H, Nomoto Y, Tokoro S, Tsunoda M, Sekiguchi H, Kobayashi T, Funayama Y, Nagayama M, Takezawa T, Mieno M, Ueno T, Fukuda H, Iwashita C, Takahashi H, Ino Y, Kawarai Lefor A, and Yamamoto H
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- Color, Endoscopy, Gastrointestinal, Humans, Multivariate Analysis, Retrospective Studies, Helicobacter pylori, Stomach Neoplasms diagnostic imaging, Stomach Neoplasms pathology, Stomach Neoplasms surgery
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Objectives: Early gastric cancers (EGCs) of the elevated type or with submucosal invasion are easily found by routine endoscopy. However, most early cancers are challenging to detect because of subtle morphological or color differences from surrounding atrophic mucosa and intestinal metaplasia. Linked color imaging (LCI) enhances mucosal color difference, making it easier to detect EGCs. The aim of this study is to clarify the advantages and possible disadvantages of LCI for screening for obscure EGC., Methods: A total of 665 malignant gastric lesions resected using endoscopic submucosal dissection between January 2015 and April 2018 were retrospectively reviewed. Obviously detectable lesions were not included in the main analysis when determining the target lesion. White light imaging (WLI)/LCI images of 508 endoscopically obscure malignant lesions were included in the final analysis and evaluated by three non-expert and three expert endoscopists using visibility scores for detection and extent., Results: The detection visibility scores using LCI were significantly higher than those using WLI regardless of lesion characteristics including location, size, histological type, depth of invasion, and Helicobacter pylori status. The detection score improved in 46.4% cases and deteriorated in 4.9% when the modality changed from WLI to LCI. A mixed-effects multivariate logistic regression analysis showed that use of LCI (odds ratio [OR] 2.57), elevated type (OR 1.92), invasion to submucosa (OR 2.18) were significantly associated with improved visibility of EGC., Conclusions: Linked color imaging significantly improves visibility of EGC regardless of differences in lesion morphology, histology, location, depth of invasion, and H. pylori status compared to conventional WLI., (© 2021 Japan Gastroenterological Endoscopy Society.)
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- 2022
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17. Improved detection of early gastric cancer with linked color imaging using an ultrathin endoscope: a video-based analysis.
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Khurelbaatar T, Miura Y, Osawa H, Ino Y, Takezawa T, Iwashita C, Nomoto Y, Tsunoda M, Ueno T, Takahashi H, Nagayama M, Fukuda H, Lefor AK, and Yamamoto H
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Background and study aims Ultrathin endoscopy causes a minimal gag reflex and has minimal effects on cardiopulmonary function. Linked color imaging (LCI) is useful for detection of malignancies in the digestive tract. The aim of this study was to clarify whether LCI with ultrathin endoscopy facilitates detection of early gastric cancer (EGC) despite its lower resolution compared with high-resolution white light imaging (WLI) with standard endoscopy. Patients and methods This was a retrospective analysis with prospectively collected video, including consecutive 166 cases of EGC or gastric atrophy alone. Ninety seconds of screening video was collected using standard and ultrathin endoscopes with both WLI and LCI for each case. Three expert endoscopists assessed each video and the sensitivity of detecting EGC calculated. Color difference calculations were performed. Results Sensitivities using ultrathin WLI, ultrathin LCI, standard WLI, and standard LCI for the identification of cancer were 66.0 %, 80.3 %, 69.9 %, and 84.0 %, respectively. The color difference between malignant lesions and surrounding mucosa with ultrathin LCI and standard LCI were significantly higher than using ultrathin WLI or standard WLI, supported subjectively by the visibility score. Ultrathin LCI color difference and visibility score were significantly higher than standard WLI. Conclusions LCI with a low-resolution ultrathin endoscope is superior to WLI with a high-resolution standard endoscope for gastric cancer screening. This suggests that the high color contrast between EGC and the surrounding mucosa is more important than high-resolution images., Competing Interests: Competing interests Dr. Yamamoto has patents for ESD devices and double-balloon endoscopy produced by Fujifilm Corporation. He has a consultant relationship with the Fujifilm Corporation and has received honoraria, grants, and royalties from the company. Drs. Osawa and Miura have received honoraria from Fujifilm Corporation., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).)
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- 2022
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18. Endoscopic ischemic polypectomy for small-bowel polyps in patients with Peutz-Jeghers syndrome.
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Khurelbaatar T, Sakamoto H, Yano T, Sagara Y, Dashnyam U, Shinozaki S, Sunada K, Lefor AK, and Yamamoto H
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- Acute Disease, Endoscopy, Humans, Intestinal Polyps complications, Intestinal Polyps surgery, Retrospective Studies, Pancreatitis, Peutz-Jeghers Syndrome complications, Peutz-Jeghers Syndrome surgery
- Abstract
Background: To decrease the risk of bleeding or perforation, ischemic polypectomy is performed using a detachable snare or endoclip with double-balloon endoscopy (DBE) for small-bowel polyps in patients with Peutz - Jeghers syndrome. The aim of this study was to determine the effectiveness and feasibility of ischemic polypectomy., Methods: We retrospectively reviewed patients who underwent two or more sessions of ischemic polypectomy using DBE from July 2004 to August 2017., Results: 67 therapeutic DBEs were performed in nine patients during the study period and 352 polyps were treated. The median observation period was 34 months (range 12 - 66). There was a declining trend over time in the median number of polyps > 15 mm treated per patient first DBE session 6, second 2, third 1.5, fourth 0.5, fifth 0.5; P = 0.11, Friedman test). No patient required laparotomy due to intussusception during the study period. One patient developed mild acute pancreatitis after the procedure., Conclusions: Ischemic polypectomy was feasible for the control of small-bowel polyps in patients with Peutz - Jeghers syndrome., Competing Interests: Dr. Yamamoto is a consultant for Fujifilm Corp. and has received honoraria, grants, and royalties from the company. Drs. Sakamoto, Yano, and Sunada have received honoraria from Fujifilm Corp. Dr. Sakamoto has also received a grant from Fujifilm Medical Corporation. Other authors declare no conflicts of interest regarding this study., (Thieme. All rights reserved.)
- Published
- 2021
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19. New Diagnostic Approach for Esophageal Squamous Cell Neoplasms Using Linked Color Imaging and Blue Laser Imaging Combined with Iodine Staining.
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Tsunoda M, Miura Y, Osawa H, Khurelbaatar T, Sakaguchi M, Fukuda H, Lefor AK, and Yamamoto H
- Abstract
A 62-year-old man with a flat early esophageal cancer was referred for endoscopic treatment. White light imaging revealed a pale red lesion, whereas linked color imaging (LCI) and blue laser imaging (BLI) yielded purple and brown images, respectively. Iodine staining demonstrated a large unstained area with a homogenous but very weak pink-color sign. This area appeared more clearly as purple and green on LCI and BLI, respectively; however, a different colored portion was observed at the 4 o'clock position inside the iodineunstained area. Histopathology findings of the resected specimen revealed squamous intraepithelial neoplasia at the 4 o'clock position and an esophageal squamous cell carcinoma in the remaining iodine-unstained area. LCI and BLI combined with iodine staining produce characteristic images that overcomes the pink-color sign, reflecting the histological features of a flat esophageal neoplasm. This new method is useful for detailed evaluation of early flat squamous cell neoplasms.
- Published
- 2019
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20. Linked color imaging can enhance recognition of early gastric cancer by high color contrast to surrounding gastric intestinal metaplasia.
- Author
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Fukuda H, Miura Y, Osawa H, Takezawa T, Ino Y, Okada M, Khurelbaatar T, Lefor AK, and Yamamoto H
- Subjects
- Aged, Biopsy, Chronic Disease, Color, Colorimetry, Female, Gastritis pathology, Humans, Male, Metaplasia diagnostic imaging, Middle Aged, Prospective Studies, Stomach Neoplasms pathology, Gastric Mucosa diagnostic imaging, Gastric Mucosa pathology, Gastritis diagnostic imaging, Stomach Neoplasms diagnostic imaging
- Abstract
Background: Linked color imaging (LCI) increases the visibility of early gastric cancers, which may be associated with characteristic findings including background purple mucosae. These lesions are found in areas of chronic gastritis and surrounding mucosa. The aim of this study is to objectively characterize these lesions by color differences and color component values using LCI., Methods: Fifty-two patients with early gastric cancer were enrolled. Color differences were calculated prospectively in malignant lesions and adjacent mucosa and compared with histological findings in resected specimens. Color component values of L*, a*, and b* were compared between purple and non-purple mucosae in areas of chronic gastritis. Based on histological findings, the accuracy of identifying gastric intestinal metaplasia was calculated., Results: Cancers and surrounding mucosa in 74% of lesions had similar colors using white light imaging (WLI), whereas purple mucosa surrounded part or all of cancers appearing orange-red, orange or orange-white using LCI. Greater color differences were seen using LCI compared to WLI, including flat-type cancers, leading to higher contrast. The surrounding purple mucosa corresponded histologically to intestinal metaplasia, facilitating the identification of malignant lesions. Forty lesions (83%) with purple mucosa and eight lesions (17%) with non-purple mucosa in areas of chronic gastritis were diagnosed as intestinal metaplasia by biopsy (83% accuracy). Color component values of purple mucosa differ significantly from those of non-purple mucosae., Conclusions: LCI images have higher color contrast between early gastric cancers and surrounding mucosa compared to WLI. A characteristic purple color around gastric cancers using LCI represents intestinal metaplasia.
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- 2019
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21. Advanced Treatment and Imaging in Colonoscopy: The Pocket-Creation Method for Complete Resection and Linked Color Imaging for Better Detection of Early Neoplastic Lesions by Colonoscopy.
- Author
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Yamamoto H, Shinozaki S, Hayashi Y, Miura Y, Khurelbaatar T, Osawa H, and Lefor AK
- Abstract
Early detection and resection of neoplastic lesions are key objectives to diminish colorectal cancer mortality. Resection of superficial colorectal neoplasms, cold snare polypectomy, endoscopic mucosal resection, and endoscopic submucosal dissection have all been developed and used worldwide. The pocket-creation method facilitates the resection of tumors in difficult and routine locations. Early detection is the most important first step to maximize the benefits of recent advancements in endoscopic techniques. However, the detection of small, flat-shaped, or faded color lesions remains difficult. Linked color imaging, a novel multi-light technology, facilitates the recognition of minor differences in tissue by enhancing the color contrast between early colorectal neoplasms and surrounding normal mucosa in a bright field of view. The most striking feature of linked color imaging is its ability to display the color of early neoplastic lesions as distinct from inflammatory changes, both of which have similar "redness" when viewed using white light imaging. To increase the detection rate of neoplasms, linked color imaging should be used from the outset for endoscopic observation. Early detection of superficial colorectal tumors can result in decreased mortality from colorectal cancer and maintain a good quality of life for patients.
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- 2019
- Full Text
- View/download PDF
22. Linked Color Imaging and Blue Laser Imaging for Upper Gastrointestinal Screening.
- Author
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Osawa H, Miura Y, Takezawa T, Ino Y, Khurelbaatar T, Sagara Y, Lefor AK, and Yamamoto H
- Abstract
White light imaging (WLI) may not reveal early upper gastrointestinal cancers. Linked color imaging (LCI) produces bright images in the distant view and is performed for the same screening indications as WLI. LCI and blue laser imaging (BLI) provide excellent visibility of gastric cancers in high color contrast with respect to the surrounding tissue. The characteristic purple and green color of metaplasias on LCI and BLI, respectively, serve to increase the contrast while visualizing gastric cancers regardless of a history of Helicobacter pylori eradication. LCI facilitates color-based recognition of early gastric cancers of all morphological types, including flat lesions or those in an H. pylori-negative normal background mucosa as well as the diagnosis of inflamed mucosae including erosions. LCI reveals changes in mucosal color before the appearance of morphological changes in various gastric lesions. BLI is superior to LCI in the detection of early esophageal cancers and abnormal findings of microstructure and microvasculature in close-up views of upper gastrointestinal cancers. Excellent images can also be obtained with transnasal endoscopy. Using a combination of these modalities allows one to obtain images useful for establishing a diagnosis. It is important to observe esophageal cancers (brown) using BLI and gastric cancers (orange) surrounded by intestinal metaplasia (purple) and duodenal cancers (orange) by LCI.
- Published
- 2018
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23. Scalp metastasis from endometrial carcinoma: a case report and literature review.
- Author
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Khurelbaatar T, Ryu KJ, Min KJ, Lee S, Hong JH, Song JY, Lee JK, and Lee NW
- Subjects
- Antineoplastic Agents therapeutic use, Carboplatin administration & dosage, Carcinoma, Endometrioid pathology, Carcinoma, Endometrioid therapy, Consolidation Chemotherapy, Diabetes Mellitus, Type 2 complications, Endometrial Neoplasms surgery, Female, Head and Neck Neoplasms drug therapy, Head and Neck Neoplasms pathology, Humans, Hysterectomy, Liver Neoplasms drug therapy, Liver Neoplasms secondary, Middle Aged, Obesity complications, Paclitaxel administration & dosage, Salpingo-oophorectomy, Skin Neoplasms drug therapy, Skin Neoplasms pathology, Carcinoma, Endometrioid secondary, Endometrial Neoplasms pathology, Head and Neck Neoplasms secondary, Scalp, Skin Neoplasms secondary
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- 2018
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24. A Cervico-Thoraco-Lumbar Multibody Dynamic Model for the Estimation of Joint Loads and Muscle Forces.
- Author
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Khurelbaatar T, Kim K, and Hyuk Kim Y
- Subjects
- Cervical Vertebrae anatomy & histology, Cervical Vertebrae physiology, Finite Element Analysis, Humans, Intervertebral Disc anatomy & histology, Intervertebral Disc physiology, Ligaments anatomy & histology, Ligaments physiology, Lumbar Vertebrae anatomy & histology, Lumbar Vertebrae physiology, Male, Muscles anatomy & histology, Thoracic Vertebrae anatomy & histology, Thoracic Vertebrae physiology, Weight-Bearing, Young Adult, Zygapophyseal Joint anatomy & histology, Zygapophyseal Joint physiology, Models, Anatomic, Muscles physiology, Spine anatomy & histology, Spine physiology
- Abstract
Computational musculoskeletal models have been developed to predict mechanical joint loads on the human spine, such as the forces and moments applied to vertebral and facet joints and the forces that act on ligaments and muscles because of difficulties in the direct measurement of joint loads. However, many whole-spine models lack certain elements. For example, the detailed facet joints in the cervical region or the whole spine region may not be implemented. In this study, a detailed cervico-thoraco-lumbar multibody musculoskeletal model with all major ligaments, separated structures of facet contact and intervertebral disk joints, and the rib cage was developed. The model was validated by comparing the intersegmental rotations, ligament tensile forces, facet joint contact forces, compressive and shear forces on disks, and muscle forces were to those reported in previous experimental and computational studies both by region (cervical, thoracic, or lumbar regions) and for the whole model. The comparisons demonstrated that our whole spine model is consistent with in vitro and in vivo experimental studies and with computational studies. The model developed in this study can be used in further studies to better understand spine structures and injury mechanisms of spinal disorders.
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- 2015
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25. Consistent accuracy in whole-body joint kinetics during gait using wearable inertial motion sensors and in-shoe pressure sensors.
- Author
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Khurelbaatar T, Kim K, Lee S, and Kim YH
- Subjects
- Acceleration, Adult, Biomechanical Phenomena physiology, Equipment Design, Feasibility Studies, Humans, Male, Signal Processing, Computer-Assisted instrumentation, Software, Statistics as Topic, Arthrometry, Articular instrumentation, Gait physiology, Joints physiology, Kinetics, Monitoring, Ambulatory instrumentation, Postural Balance physiology, Weight-Bearing physiology
- Abstract
To analyze human motion such as daily activities or sports outside of the laboratory, wearable motion analysis systems have been recently developed. In this study, the joint forces and moments in whole-body joints during gait were evaluated using a wearable motion analysis system consisting of an inertial motion measurement system and an in-shoe pressure sensor system. The magnitudes of the joint forces and the moments in nine joints (cervical, thoracic, lumbar, right shoulder, right elbow, right wrist, right hip, right knee, and right ankle) during gait were calculated using the wearable system and the conventional system, respectively, based on a standard inverse dynamics analysis. The averaged magnitudes of the joint forces and moments of five subjects were compared between the wearable and conventional systems in terms of the Pearson's correlation coefficient and the normalized root mean squared error to the maximum value from the conventional system. The results indicated that both the joint forces and joint moments in human whole body joints using wearable inertial motion sensors and in-shoe pressure sensors were feasible for normal motions with a low speed such as walking, although the lower extremity joints showed the strongest correlation and overall the joint moments were associated with relatively smaller correlation coefficients and larger normalized root mean squared errors in comparison with the joint forces. The portability and mobility of this wearable system can provide wide applicability in both clinical and sports motion analyses., (Copyright © 2015 Elsevier B.V. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
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