The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on March 11, 2011 resulted in the release of immense amounts of radioactive materials into the ocean. However, the dispersion of radioactive materials in the subsurface has not yet been clarified due to the spatiotemporal limitation of observations. Thus, herein, a tracer experiment was implemented using a three-dimensional numerical model to estimate the dispersion path of 137Cs released directly from the FDNPP and its travel time in the subsurface of the North Pacific Ocean from 2011 to 2020. The results show that the subsurface 137Cs spreads by two mode waters, namely, Sub-Tropical Mode Water (STMW) and Central Mode Water (CMW). Subsurface 137Cs primarily spreads clockwise in the sub-tropical region, while a portion driven by STMW is dispersed southward. The clockwise dispersion path of 137Cs released into the ocean by STMW is relatively shallower and inward than that by CMW. The 137Cs that was spread clockwise reached the east of Taiwan and the Philippines via STMW and CMW nine years after the accident, respectively. The model described in this study is applicable for estimating the water path and travel time of tritium water planned to be discharged from Fukushima.

Unprecedented coastal upwelling off the southern coast of the Korean Peninsula was reported during the summer of 2013. The upwelling continued for more than a month after a plunge in upwellingfavourable winds and had serious impacts on fisheries. This is a rare phenomenon, as most coastal upwelling events relax a few days after the wind weakens. In this study, observational data and numerical modelling results were analysed to investigate the cause of the upwelling and the reason behind it being sustained for such an extended period. Coastal upwelling was induced by an upwellingfavourable wind in July, resulting in the dynamic uplift of deep, cold water. The dynamic uplift decreased the steric sea level in the coastal region. The sea level difference between the coastal and offshore regions produced an intensified cross-shore pressure gradient that enhanced the surface geostrophic current along the coast. The strong surface current maintained the dynamic uplift due to geostrophic equilibrium. This positive feedback between the dynamic uplift and geostrophic adjustment sustained the coastal upwelling for a month following a plunge in the upwellingfavourable wind. Coastal upwelling is a process that brings deep, cold water to the ocean surface. It can play an important role both in physical processes and in chemical and biological variability in coastal regions by transporting nutrients to the surface layer. Coastal upwelling can be induced by various mechanisms, but it generally results from Ekman transport due to the alongshore wind stress 1,2. Wind stress curl can also induce coastal upwelling 3. The current along a coastal region may enhance the onshore Ekman pumping through the bottom boundary layer 4,5. Upwelling occurs as a form of dynamic (isotherm) uplift that results from geostrophic equilibrium, which is a balance between the pressure gradient force (PGF) and the Coriolis force 6,7. The southern sea region off the Korean Peninsula connects the East China Sea and the East/Japan Sea. The mean depth of this offshore region is approximately 100 m. There is an eastward alongshore flow throughout the year 8,9. A two-layer structure, comprising warm water in the upper layer and cold water in the lower layer, forms during the summer. The surface waters that originate from the Kuroshio and East China Sea are heated by the atmosphere. The deep, cold water originates from the west 10,11. Unprecedented coastal upwelling was reported in various observations during August 2013. The sea surface temperature (SST) in the coastal region was 2 °C lower than the climatic SST (10 years mean) in the coastal region, whereas the offshore SST was 2 °C higher due to a hot summer in 2013 (Fig. 1c). The cold SST in the coastal region persisted for more than a month after the upwelling-favourable wind weakened (Fig. 1e). The upwelling had serious impacts on the fish farms in this area. In this study, observational data analyses and numerical modelling were performed to investigate the reason for the unprecedented coastal upwelling, ...

Diagnosing osteosarcoma (OS) is very challenging and OS is often misdiagnosed as osteomyelitis (OM) due to the nonspecificity of its symptoms upon initial presentation. This study investigated the possibility of detecting OS-induced trabecular bone changes on panoramic radiographs and differentiating OS from OM by analyzing fractal dimensions (FDs) and degrees of anisotropy (DAs). Panoramic radiographs of patients with histopathologically proven OS and OM of the jaw were obtained. A total of 23 patients with OS and 40 patients with OM were enrolled. To investigate whether there was a microarchitectural difference between OS lesions and normal trabecular areas in each patient, two regions of interest (ROIs) were located on the CT images. Three microarchitectural parameters (box-counting FD, fast Fourier transform-based FD, and DA) were calculated. For both OS and OM, significant differences were found for all three microarchitectural parameters. Compared to normal trabecular bone, trabecular bone affected by OS and OM became isotropic and more complex. When comparing OS and OM, a statistically significant difference was found only in DA. Trabecular bones affected by OS became more isotropic than those affected by OM. Microarchitectural analysis, especially DA, could be useful for detecting OS-induced trabecular alterations and differentiating OS from OM.

Upwelling in coastal regions is of particular interest to environmental researchers owing to its crucial role in coastal environmental studies. The process plays a key role in distributing not only heat and salt, but also nutrients and biological products in the upwelling region. Coastal upwelling can be induced for various reasons but generally results from Ekman transport due to alongshore winds (Ekman, 1905).It is essential to quantitatively evaluate the coastal upwelling intensity, which can act as a proxy for estimating biological and chemical impacts on the coastal environment (

<p>Unprecedented coastal upwelling in the southern coast of the Korean peninsula was reported in the summer of 2013. The offshore water temperature was 2℃ higher than that of climate (10-year mean) due to the hot summer in 2013. However, the water temperature at the coastal region was 2℃ lower. The upwelling continued for a month despite of weakening of upwelling-favorable wind. In this study, observational data and numerical model results were analyzed to investigate what caused the upwelling and sustained it for a long time. The upwelling was induced by upwelling-favorable wind in July. Coastal upwelling resulted in dynamic uplift of bottom cold water due to geostrophic adjustment. The dynamic uplift decreased sea level in the coastal region. The sea level difference between coastal and offshore regions resulted in an intensified cross-shore pressure gradient which induced geostrophic current accompanied by geostrophic adjustment along the coast. This positive feedback between dynamic uplift and geostrophic adjustment sustained the coastal upwelling for a long time regardless of upwelling-favorable wind.</p>