Kyung Duck Min

Waterline extraction from Landsat TM data in a tidal flat. A case study in Gomso Bay, Korea

Waterline extraction is potentially one of the most effective satellite remote sensing tools for studying changes in tidal flat environment and coastlines. However, its application to the study of tidal flats has not been investigated in detail. The waterline in a tidal flat in Gomso Bay, Korea is characterized and evaluated using 27 sets of Landsat thematic mapper (TM) and Earth Observing System-Terra (EOS-Terra) Advanced Spaceborne Thermal Emission and Radiometer (ASTER) data. Ground truth data including grain size, soil moisture content, ground levelling, and waterline tracking have been obtained. The choice of spectral bands in terms of tidal conditions turned out to play a key role in locating the waterline. While the waterlines extracted from near-infrared (NIR), short-wavelength infrared (SWIR), and thermal infrared (TIR) data are commonly reliable on the flood tide, the discrepancies between different bands become large on the ebb tide. The bands TIR, NIR, and SWIR are, in that order, decreasingly effective in extracting the waterline while ebb tides are in progress. The effect of turbid water on NIR can be reduced by a ratioing of NIR and the visible band. The location of the waterline is also an important factor to consider; the discrepancy is largest on the middle tidal flat. Selection of the proper band for waterline extraction under various conditions is suggested. However, no single band can accommodate all aspects of the tidal flat environment. A schematic model associated with the spectral reflectance of the tidal flat is proposed in which the remnant water scattered on the surface after exposure is emphasized as an additional factor.

Bevacizumab application delays epithelial healing in rabbit cornea.

PURPOSE Vascular endothelial growth factor (VEGF) is essential for neovascularization, but the use of anti-VEGF therapies to inhibit neovascularization may influence epithelial wound healing. Here, the effects of bevacizumab on corneal epithelial wound healing time in rabbit models, cell proliferation, and expression of integrins in human corneal epithelial and fibroblast cells were evaluated. METHODS To compare epithelial wound healing times, epithelial defect sizes were measured after application of bevacizumab topical eye drops at 0, 0.5, 1.0, 1.5, 2.5, or 5 mg/mL, twice daily, to mechanically debrided epithelia of rabbit corneas. The cellular covering of wounded areas and expression of Ki67 were assessed after scrape injuries in cultures of human corneal epithelial and fibroblast cells. Expression of cell surface integrins and collagens was measured using plates coated with mouse monoclonal antibodies against human adhesion molecules, and relevant mRNA levels were assessed by reverse-transcription-polymerase chain reaction (RT-PCR). RESULTS The application of bevacizumab topical eye drops at 1.0, 1.5, 2.5, or 5 mg/mL delayed rabbit corneal epithelial healing. Cell cultures growing under high concentrations of bevacizumab showed delay in the proliferation of corneal epithelial and fibroblast cells. Surface expression of mRNA encoding integrins and collagens were decreased by 1.5 mg/mL of bevacizumab. CONCLUSIONS Bevacizumab delayed corneal epithelial wound healing and inhibited integrin expression. When bevacizumab is used to reduce the development of new corneal vessels, slight delays in epithelial wound healing are possible and cellular proliferation is to be expected.

Minocycline Controls Clinical Outcomes and Inflammatory Cytokines in Moderate and Severe Meibomian Gland Dysfunction

PURPOSE To assess clinical outcomes and tear cytokine levels in patients with moderate and severe meibomian gland dysfunction (MGD) after treatment with oral minocycline and artificial tears versus artificial tears only. DESIGN Prospective, randomized clinical trial. METHODS Sixty eyes of 60 patients with stage 3 or 4 meibomian gland dysfunction were enrolled. We evaluated the tear film break-up time, Schirmer test results, corneal and conjunctival fluorescein staining results, biomicroscopic examination results of lid margins and meibomian glands, and tear cytokine levels before and after 1 month and 2 months of oral minocycline and artificial tears (group 1) or artificial tears only (group 2). Tear samples were collected and analyzed using a BD Cytometric Bead Array (BD Bioscience, San Jose, California, USA) for detection of interleukin (IL)-1β, IL-6, IL-7, IL-8, IL-12p70, IL-17α, interferon-γ, tumor necrosis factor-α, and monocyte chemotactic protein-1. The Wilcoxon signed-rank test, Mann-Whitney U test, generalized linear model, and linear mixed model were performed. RESULTS Patients in group 1 showed statistically significant improvement in all clinical signs and symptoms after 1 month and 2 months of treatment. Patients of group 1 showed more significant improvement compared with those in group 2. Patients in group 1 also showed statistically significant reductions in IL-6, IL-1β, IL-17α, tumor necrosis factor-α, and IL-12p70 after 2 months of treatment. CONCLUSIONS Oral minocycline can provide clinical benefits in treating moderate and severe meibomian gland dysfunction by reducing inflammatory cytokine levels.

Paleomagnetotectonics of East Asia in the Proto-Tethys Ocean

Abstract Seven paleomagnetic poles are obtained from Early Ordovician, Late Carboniferous, Permo-Triassic, Jurassic, Early Cretaceous, Miocene and Quaternary rocks in Korea. These poles define the apparent polar wander path for the southern part of Korean Peninsula. The comparisons of APWPs from the North China Block, Yangtze Block and Korea reveals that the East Asia is comprised of two blocks, the North Sino-Korean and South Sino-Korean, which were parts of Gondwana during the Paleozoic time. The North Sino-Korean Block was migrated northwards in Late Permian and accreted with Laurasia in Triassic time. During Middle–Late Triassic time, the North Sino-Korean Block collided with the South Sino-Korean, and subsequently divided into two. The western part of the North Sino-Korean Block suffered counter-clockwise rotation, while the eastern part rotated clockwise until Jurassic time. Complicated shear senses of the Early Mesozoic fault systems in East Asia are well matched by this scenario.

Inflammatory Cytokine and Osmolarity Changes in the Tears of Dry Eye Patients Treated with Topical 1% Methylprednisolone

Purpose To evaluate changes in clinical outcomes, inflammatory cytokine levels, and tear osmolarity in the tears of patients with moderate to severe dry eye syndrome before and after the application of topical 1% methylprednisolone. Materials and Methods Thirty-two patients with moderate to severe dry eye unresponsive to previous aqueous enhancement therapy were enrolled. Five patients were lost to follow up, and twenty-seven patients were eligible for analysis. Patients were instructed to apply topical 1% methylprednisolone four times per day, as well as to continue applying their current therapy of preservative-free 0.1% sodium hyaluronate four times per day. Corneal and conjunctival staining scores, tear film breakup time (TFBUT), Schirmer test, and tear osmolarity were assessed at baseline, 4 weeks, and 8 weeks. Tear samples were collected at every visit for cytokine analysis. Results Corneal and conjunctival staining scores and TFBUT showed significant improvement at 4 (p<0.001, <0.001, <0.001 respectively) and 8 (p<0.001, <0.001, <0.001 respectively) weeks. Tear osmolarity decreased significantly at 8 weeks (p=0.008). Interleukin (IL)-1β, IL-8, and monocyte chemoattractant protein-1 were significantly decreased at 8 weeks compared with those at baseline (p=0.041, 0.001, 0.008 respectively). Conclusion Short-term treatment with topical 1% methylprednisolone not only improved clinical outcomes, but also decreased tear osmolarity and cytokine levels. By measuring the changes in cytokine levels and tear osmolarity, we could objectively evaluate the anti-inflammatory effects of topical methylprednisolone applied in the treatment of patients with moderate to severe dry eye syndrome.

Experimental folding of rocks under confining pressure: Part IV — theoretical analysis of faulted drape-folds

Abstract Theoretical analyses of the stresses, displacements, and stress trajectories associated with faulted drape-folds are obtained for two boundary-value problems in linear elasticity. Two different conditions — welded and frictionless — are assumed for the interface between the overlying sedimentary veneer and the forcing basement rock. In nature the situation lies somewhere between these two extremes. Solutions are obtained for impulsive boundary conditions in the stresses and displacements; the solutions for spatially-varying boundary stresses and/or displacements are obtained from these by the convolution theorem. Consequently, the stresses, displacements, and stress trajectories in the sedimentary veneer can be determined for boundary stresses and/or displacements that may be non-analytic functions of position. The stress trajectories compare well with those determined by previous petrofabric analyses of experimentally deformed rock specimens. Potential faults are predicted from the calculated stress trajectories and the Coulomb-Mohr failure criterion. They are compared with those observed experimentally, and the correlations are good, even though the experimental faults have relatively large displacements. This suggests that the stress patterns established in the early (linearly elastic) stages of deformation strongly control the later stress patterns and, consequently, the sense of displacements along the faults.

Multi temporal JERS-1 SAR investigation of Mt. Baekdu stratovolcano using differential interferometry

Mt. Baekdu, a Cenozoic stratovolcano, was studied using twenty-three JERS-1 SAR and two ERS-2 SAR images. A 70-day ERS-2 interferogram produces a very poor interferogram because of the temporal decorrelation probably due to vegetation and the layover effects. However, JERS-1 SAR data pairs produce coherent interferograms even when some of the time intervals between the data take was as long as 6 years. The measurement of surface changes was numerically implemented from 1992 to 1998 using three different SAR interferometry approaches: i) interferometry with large altitude of ambiguity, ii) 2-pass, and iii) 3-pass differential SAR interferometry (DInSAR). Analysis of 11 differential interferograms indicates that the large surface area surrounding Mt. Baekdu (several tens of kilometers) subsides, particularly the southwestern part of it. When the computed displacement vectors are projected onto the vertical components, the maximum subsidence rate is estimated at 9 cm/year. Although the estimated ubsidence rate is not confirmed in the field due to the lack of ground-truth data and accurate DEMs as well as logistic problems, the results provide important volcano-tectonic implications on the background information for future long-term monitoring of Mt. Baekdu.

Miocene paleomagnetic results from southeastern Korea

Paleomagnetic samples were collected from 25 sites of Late Oligocene to Middle Miocene age from southeastern South Korea. The mean direction obtained is D = 39.4°, I = 46.2° with α95 = 9.5°, which is statistically distinguishable from the present axial geocentric dipole field direction. When combined with the previous reported results of eight sites from this region, we get a mean direction (D = 40.1°, I = 47.4°, α95= 7.9°) for 33 sites of Late Oligocene to Middle Miocene age. This direction yields an early Neogene virtual geomagnetic pole of 56.5°N, 215.2°E with an α95 of 7.9°, discordant from the Cretaceous reference pole for Korea. The paleomagnetic data suggest that portions of southeastern Korea underwent a large clockwise rotation of about 40° during the Neogene. Two large NE-trending right-lateral faults (the Yangsan Fault and the Dongnae Fault, Fig. 1) cut the study areas. Both these faults show evidence for recent activity. In addition, minor faults with similar trends to these major faults occur. The observed deflections in paleomagnetic declinations were probably caused by rigid block rotations of crustal blocks in a right lateral shear system during the Neogene. The paleomagnetic directions for Miocene aged rocks from southeastern Korea and southwestern Japan are similar in direction and magnitude. This suggests that the cause of the rotations in both areas may be related to a similar tectonic event in this area during the Neogene.

Modulation of Bevacizumab-Induced Toxicity for Cultured Human Corneal Fibroblasts

PURPOSE There are numerous reports describing the direct or indirect cellular toxicity of bevacizumab. In this study, we measured the direct toxicity of bevacizumab and determined its modulation by growth factors in cultured human corneal fibroblasts. METHODS To measure the toxicity of bevacizumab and ranibizumab on corneal fibroblasts, lactate dehydrogenase (LDH) assays, fluorescence-activated cell sorting analyses, and Ki-67 staining were performed. The role of vascular endothelial growth factor (VEGF) in bevacizumab-related toxicity was evaluated after suppression of VEGF expression using small interfering RNA (siRNA) and VEGF receptor inhibition with SU1498. We evaluated alteration of cellular toxicity and anti-angiogenic function of bevacizumab with cotreatment of basic fibroblast growth factor (bFGF) or nerve growth factor (NGF) using human corneal fibroblasts and human umbilical vein endothelial cells (HUVECs). RESULTS Application of bevacizumab induced cellular toxicity and delayed proliferation in a dose-dependent manner, but ranibizumab did not cause cellular damage. Elevated LDH observed after bevacizumab treatment was decreased by cotreatment with varying concentrations of fetal bovine serum. However, VEGF cotreatment, VEGF suppression, and VEGF receptor blocking did not influence bevacizumab-induced cell death. Cotreatment of cells with bFGF or NGF and 2 mg/mL bevacizumab reduced LDH elevation. Low-dose bFGF or NGF did not interfere with the antiangiogenic function of bevacizumab as measured by the tube formation assay and MTS (dimethylthiazol-diphenyltetrazolium bromide) assay of HUVECs. CONCLUSIONS This study determined the cellular toxicity of bevacizumab and its modulation with bFGF or NGF. Cotreatment with bFGF or NGF with bevacizumab reduced cellular damage without interfering with the original antiangiogenic function. Some components of serum have a protective effect on bevacizumab-induced corneal epithelial change.

Deep geoelectrical structure in and around the southern Korean Peninsula by GDS study

This paper presents lateral conductivity variations in the Earths crust in and around the southern Korean Peninsula, which were mapped using magnetic field variations recorded at ten sites in Korea. GDS data can provide an efficient way to identify crustal units having different conductivities. And a three-dimensional (3-D) magnetotelluric (MT) modeling based on the induction arrows revealed a major conductivity anomaly in and around the Korean Peninsula. The comparison of observed and modeled induction arrows strongly suggests evidence of a relationship between main tectonic belts and the deep conductivity anomalies in this area. The overall pattern of induction arrows in this area appears to indicate a northwest-southeast direction, which is similar to that of the so-called ‘sea effect’, affected by the surrounding sea. However, the results of observations in the middle of the peninsula imply an anomalous pattern in the tectonic area near the Imjin River Belt. Induction arrows in the mid-southern area appear to be related to a thick sedimentary pile, the Ogcheon Belt, which forms another tectonic boundary in the Korean Peninsula. The overall pattern of arrows observed in the coastal area and islands was affected by the sea effect. The pattern, which shows southward arrows similar to those in the previous study of the southern coastline of the peninsula and Jeju Island near Kyushu, Japan, might indicate highly conductive anomalies (HCL) (Shimoizumi et al., 1997). However, the sea effect seems to be weak in the western coastal region, probably because the Yellow Sea is much shallower than the East Sea (Sea of Japan), and this phenomenon leads to the possibility of discerning an anomalous pattern beneath the Yellow Sea.