Disaster report of 2018 July heavy rain for geo-structures and slopes in Okayama

In July 2018, heavy rain and a large amount of damage to geo-structures and natural slopes were reported in Okayama, Japan. In particular, in the area surrounding the Oda River System, 52 people drowned due to the breach of river banks. Besides the flooding of rivers, the earth-fill dams of many water reservoirs were damaged. The stability of the large number of earth-fill dams in the Setouchi area is very important. Heavy rain is often associated with the collapse of slopes. In Okayama, many shallow slope failures or debris flows occurred over a wide area, particularly in the western part of the prefecture. Through detailed investigations, the mechanism of this geo-disaster was clarified

Efficacy of the New Neuraminidase Inhibitor CS-8958 against H5N1 Influenza Viruses

Currently, two neuraminidase (NA) inhibitors, oseltamivir and zanamivir, which must be administrated twice daily for 5 days for maximum therapeutic effect, are licensed for the treatment of influenza. However, oseltamivir-resistant mutants of seasonal H1N1 and highly pathogenic H5N1 avian influenza A viruses have emerged. Therefore, alternative antiviral agents are needed. Recently, a new neuraminidase inhibitor, R-125489, and its prodrug, CS-8958, have been developed. CS-8958 functions as a long-acting NA inhibitor in vivo (mice) and is efficacious against seasonal influenza strains following a single intranasal dose. Here, we tested the efficacy of this compound against H5N1 influenza viruses, which have spread across several continents and caused epidemics with high morbidity and mortality. We demonstrated that R-125489 interferes with the NA activity of H5N1 viruses, including oseltamivir-resistant and different clade strains. A single dose of CS-8958 (1,500 µg/kg) given to mice 2 h post-infection with H5N1 influenza viruses produced a higher survival rate than did continuous five-day administration of oseltamivir (50 mg/kg twice daily). Virus titers in lungs and brain were substantially lower in infected mice treated with a single dose of CS-8958 than in those treated with the five-day course of oseltamivir. CS-8958 was also highly efficacious against highly pathogenic H5N1 influenza virus and oseltamivir-resistant variants. A single dose of CS-8958 given seven days prior to virus infection also protected mice against H5N1 virus lethal infection. To evaluate the improved efficacy of CS-8958 over oseltamivir, the binding stability of R-125489 to various subtypes of influenza virus was assessed and compared with that of other NA inhibitors. We found that R-125489 bound to NA more tightly than did any other NA inhibitor tested. Our results indicate that CS-8958 is highly effective for the treatment and prophylaxis of infection with H5N1 influenza viruses, including oseltamivir-resistant mutants

Uncertainty in centrifuge test of slope failure and its simulation by MPS method

We sometimes encounter a case in which very small change of computation or experiment condition causes the significant difference in response when strong nonlinearity is involved. Slope failure simulation due to gravity by MPS method is performed to examine feature of uncertainty. The simulation results show that the output uncertainty is proportional to input uncertainty in weak nonlinear or linear behavior. In strong nonlinear behavior, the output uncertainty is constant irrespective of uncertainty level of input data when the input uncertainty is less than certain level. The range of the constant uncertainty depends on the strength of nonlinearity in the phenomenon. Comparison of uncertainties in centrifuge slope failure test and its simulation by MPS method is shown and discussed

Uncertainty in centrifuge test of slope failure and its simulation by MPS method

We sometimes encounter a case in which very small change of computation or experiment condition causes the significant difference in response when strong nonlinearity is involved. Slope failure simulation due to gravity by MPS method is performed to examine feature of uncertainty. The simulation results show that the output uncertainty is proportional to input uncertainty in weak nonlinear or linear behavior. In strong nonlinear behavior, the output uncertainty is constant irrespective of uncertainty level of input data when the input uncertainty is less than certain level. The range of the constant uncertainty depends on the strength of nonlinearity in the phenomenon. Comparison of uncertainties in centrifuge slope failure test and its simulation by MPS method is shown and discussed

Diagnosis of Earth-Fill Dams by Several Sounding Tests

The spatial distribution of the strength inside an earth-fill dam is identified by sounding tests. In this research, the Swedish Weight Sounding (SWS) test is employed, and the spatially high-density test is possible to identify the spatial correlation structure by the SWS. The correlation structure of an earth-fill could be identified accurately based on the sounding results, and the high resolution of the spatial distribution could be visualized by using the indicator simulation. Consequently, it has been verified the practical use of the spatial distribution of the probability that the N-value is lower than the threshold value, may be used for the maintenance of an earth-fill dam

Uncertainty Evaluation in Slope Failure using Centrifuge Model Tests

Strong nonlinear behavior such as slope failure involves large uncertainties. Even if we conduct model tests on slope failure under the same test conditions, we cannot reproduce the same results although the linear behavior can be reproduced with relative ease. This kind of uncertainties is well known as “aleatory uncertainty” and they should be distinguished clearly from the epistemic uncertainty in reliability-based design. However, characteristics of aleatory uncertainty have not been studied very well so far. This study quantitatively investigates the aleatory uncertainties involved in failure behavior of slopes thorough centrifuge model tests. The centrifuge model tests were conducted under the same test conditions twenty times to quantitatively investigate the variability of slip lines

Geotechnical uncertainty, modeling, and decision making

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