Experimental and Numerical Study of Tsunami Wave Propagation and Run-Up on Sloping Beaches

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Sediment Budget in the Taiwan Strait with High Fluvial Sediment Inputs from Mountainous Rivers: New Observations and Synthesis

The shallow Taiwan Strait at the southern opening of the East China Sea (ECS) receives abundant sediments from turbid mountainous rivers in Taiwan. The volume of sediment is among the highest sediment yields on the global surface. This large amount of sediment discharged from modern Taiwan (range: 175 - 380 Mt y-1 based on 50-yr data) is comparable to that discharged from Changjaing (500 Mt y-1-decreasing in recent decades), underscoring the importance of sediment budget in the Taiwan Strait and sediment flux from Taiwan into the ECS.We documented fluvial mud and sand concentrations during flash flooding with our observations indicating that fluvial materials in Taiwan¡¦s rivers are chiefly composed of mud (> 70 and up to 98 ). By contrast, sand fraction dominates (> 85 for most stations) surface sediments in the Taiwan Strait. Super typhoon Herb alone delivered 130 Mt of sediments from Choshui, the largest river in Taiwan, yet only insignificant amounts of mud were found at the river mouth six months later. The actions of waves, tides, and currents apparently prevent the deposition of fine grained sediments. Assuming sand occupied 30 (the maximum) of the 60 Mt y-1 total sediment input from major western Taiwanese rivers, our annual budget estimate shows that the amount of sand input (18 5 Mt y-1) is comparable to the burial output of sand (12 10 Mt y-1). However, mud burial (6 5 Mt y-1) in the strait is far below the estimated mud input (42 11 Mt y-1), resulting in a significant shortfall. Hydrodynamic conditions were synthesized to explain the distribution pattern of limited mud patches in the strait and to reveal potential pathways by which fine-grain sediment transportation takes place in the seas surrounding Taiwan. A significant shortfall in the mud budget in the Taiwan Strait suggests that ~85 of the fluvial mud left the strait. Alternatively, the 50-year modern sediment flux data used in this study reflects exacerbated sediment flux due to human activity and is possibly too high to represent loads during pre-Anthropocene. Additional studies are needed to explore the flux and fate of mud in and surrounding Taiwan over a longer time scale

Sitagliptin and Fractures in Type 2 Diabetes: A Nationwide Population-Based Propensity-Matching Study

Background: Sitagliptin, a dipeptidyl peptidase-4 inhibitor possibly affects bone turnover. We conducted this cohort study to determine whether sitagliptin is associated with an increased risk of fracture.Methods: The sitagliptin cohort included 1,578 patients aged 20 years and above. The nonsitagliptin cohort comprised propensity-score matched patients at a ratio of 1:1. The primary outcome was the incidence of fractures, which was evaluated using Kaplan–Meier survival analysis and proportional hazards modeling.Results: The mean age of patients in the sitagliptin and nonsitagliptin cohorts was 63.1 and 63.3 years, respectively. The incidence of fractures in the sitagliptin cohort was 46 per 1,000 person-years and that in the nonsitagliptin cohort was 40.8 per 1,000 person-years. Compared with patients in the nonsitagliptin cohort, those in the sitagliptin cohort who received sitagliptin for ≥250 days had a higher risk of fracture (aHR = 1.32, 95% CI = 1.06–1.64).Conclusion: Using sitaglipin ≥250 days was associated with an increased risk of fracture

Extreme hydrological changes in the southwestern US drive reductions in water supply to Southern California by mid century

The Southwestern United States has a greater vulnerability to climate change impacts on water security due to a reliance on snowmelt driven imported water. The State of California, which is the most populous and agriculturally productive in the United States, depends on an extensive artificial water storage and conveyance system primarily for irrigated agriculture, municipal and industrial supply and hydropower generation. Here we take an integrative high-resolution ensemble modeling approach to examine near term climate change impacts on all imported and local sources of water supply to Southern California. While annual precipitation is projected to remain the same or slightly increase, rising temperatures result in a shift towards more rainfall, reduced cold season snowpack and earlier snowmelt. Associated with these hydrological changes are substantial increases in the frequency and the intensity of both drier conditions and flooding events. The 50 year extreme daily maximum precipitation and runoff events are 1.5–6 times more likely to occur depending on the water supply basin. Simultaneously, a clear deficit in total annual runoff over mountainous snow generating regions like the Sierra Nevada is projected. On one hand, the greater probability of drought decreases imported water supply availability. On the other hand, earlier snowmelt and significantly stronger winter precipitation events pose increased flood risk requiring water releases from control reservoirs, which may potentially decrease water availability outside of the wet season. Lack of timely local water resource expansion coupled with projected climate changes and population increases may leave the area in extended periods of shortages

Bmi-1 Regulates Snail Expression and Promotes Metastasis Ability in Head and Neck Squamous Cancer-Derived ALDH1 Positive Cells

Recent studies suggest that ALDH1 is a putative marker for HNSCC-derived cancer stem cells. However, the regulation mechanisms that maintain the stemness and metastatic capability of HNSCC-ALDH1+ cells remain unclear. Initially, HNSCC-ALDH1+ cells from HNSCC patient showed cancer stemness properties, and high expression of Bmi1 and Snail. Functionally, tumorigenic properties of HNSCC-ALDH1+ cells could be downregulated by knockdown of Bmi-1. Overexpression of Bmi-1 altered in expression property ALDH1− cells to that of ALDH1+ cells. Furthermore, knockdown of Bmi-1 enhanced the radiosensitivity of radiation-treated HNSCC-ALDH1+ cells. Moreover, overexpression of Bmi-1 in HNSCC-ALDH1− cells increased tumor volume and number of pulmonary metastatic lesions by xenotransplant assay. Importantly, knock-down of Bmi1 in HNSCC-ALDH1+ cells significantly decreased distant metastases in the lungs. Clinically, coexpression of Bmi-1/Snail/ALDH1 predicted the worst prognosis in HNSCC patients. Collectively, our data suggested that Bmi-1 plays a key role in regulating Snail expression and cancer stemness properties of HNSCC-ALDH1+ cells

Study of the River Bed Variation after the Baling Check-Dam Failure

The study provides longitudinal and cross-sectional analysis of 8 pieces topography data collected from 1980 to 2011 and bed material particle size based on three investigations conducted between 2008 and 2012. The mainstream topography data in December 2007 shows that the head-cutting distance was about 3 kilometers after the dam broke. The topography data since 2008 displays that river the channel is stable as well. The topography data shows that the longitudinal section in the tributary had a head-cutting distance of about 3 kilometers after the dam broke, and the river channel still is showing adjustment behavior. The scour-and-fill analysis result of the mainstream cross-section shows that the transverse adjust changed significantly upstream from the dam location from 2006-2008. The particle size of the bed material has shown a trend from coarsening to fining according to different sampling points. Therefore, the river bed is still adjusting continuously. Finally, this study is based on a debris flow and sediment laden flow numerical model. The simulation result is fit for river-bed changes after dam-break.2007年石門水庫上游的巴陵防砂壩潰壩事件，導致上游河床沖刷約20公尺，下游最大淤積約10公尺。本文蒐集巴陵防砂壩1980至2011年潰壩前後8次地形測量資料與2008-2012年共進行三次河床質粒徑調查以分析潰壩對於河床變動及河床質粒徑變化的影響。結果顯示，巴陵壩潰壩3個月後河床已逐漸趨於動態平衡，河床質粒徑整體有粗化再細化的趨勢。最後，本文以適用於土石流及高含砂水流的數值模式進行潰壩事件模擬，並利用河床測量成果進行比較

Role of Genetic Variation in Collateral Circulation in the Evolution of Acute Stroke: A Multimodal Magnetic Resonance Imaging Study

No studies have determined the effect of differences in pial collateral extent (number and diameter), independent of differences in environmental factors and unknown genetic factors, on severity of stroke. We examined ischemic tissue evolution during acute stroke, as measured by magnetic resonance imaging (MRI) and histology, by comparing 2 congenic (CNG) mouse strains with otherwise identical genetic backgrounds but with different alleles of the Determinant of collateral extent-1 (Dce1) genetic locus. We also optimized magnetic resonance (MR) perfusion and diffusion deficit thresholds by using histological measures of ischemic tissue

Ultra high-resolution fMRI and electrophysiology of the rat primary somatosensory cortex

High-resolution functional-magnetic-resonance-imaging (fMRI) has been used to study brain functions at increasingly finer scale, but whether fMRI can accurately reflect layer-specific neuronal activities is less well understood. The present study investigated layer-specific cerebral-blood-volume (CBV) fMRI and electrophysiological responses in the rat cortex. CBV fMRI at 40×40 µm in-plane resolution was performed on an 11.7-T scanner. Electrophysiology used a 32-channel electrode array that spanned the entire cortical depth. Graded electrical stimulation was used to study activations in different cortical layers, exploiting the notion that most of the sensory-specific neurons are in layers II–V and most of the nociceptive-specific neurons are in layers V–VI. CBV response was strongest in layer IV of all stimulus amplitudes. Current source density analysis showed strong sink currents at cortical layers IV and VI. Multi-unit activities mainly appeared at layers IV–VI and peaked at layer V. Although our measures showed scaled activation profiles during modulation of stimulus amplitude and failed to detect specific recruitment at layers V and VI during noxious electrical stimuli, there appears to be discordance between CBV fMRI and electrophysiological peak responses, suggesting neurovascular uncoupling at laminar resolution. The technique implemented in the present study offers a means to investigate intracortical neurovascular function in the normal and diseased animal models at laminar resolution

Near-term acceleration of hydroclimatic change in the western U.S.

Given its large population, vigorous and water-intensive agricultural industry, and important ecological resources, the western United States presents a valuable case study for examining potential near-term changes in regional hydroclimate. Using a high-resolution, hierarchical, five-member ensemble modeling experiment that includes a global climate model (Community Climate System Model), a regional climate model (RegCM), and a hydrological model (Variable Infiltration Capacity model), we find that increases in greenhouse forcing over the next three decades result in an acceleration of decreases in spring snowpack and a transition to a substantially more liquid-dominated water resources regime. These hydroclimatic changes are associated with increases in cold-season days above freezing and decreases in the cold-season snow-to-precipitation ratio. The changes in the temperature and precipitation regime in turn result in shifts toward earlier snowmelt, base flow, and runoff dates throughout the region, as well as reduced annual and warm-season snowmelt and runoff. The simulated hydrologic response is dominated by changes in temperature, with the ensemble members exhibiting varying trends in cold-season precipitation over the next three decades but consistent negative trends in cold-season freeze days, cold-season snow-to-precipitation ratio, and 1 April snow water equivalent. Given the observed impacts of recent trends in snowpack and snowmelt runoff, the projected acceleration of hydroclimatic change in the western U.S. has important implications for the availability of water for agriculture, hydropower, and human consumption, as well as for the risk of wildfire, forest die-off, and loss of riparian habitat.Keywords: near-term projections, hydrological change, hydrological modeling, snow cover, western United State