Abstract During the endgame of global polio eradication, the universal introduction of inactivated poliovirus vaccines is urgently required to reduce the risk of vaccine-associated paralytic ...poliomyelitis and polio outbreaks due to wild and vaccine-derived polioviruses. In particular, the development of inactivated poliovirus vaccines (IPVs) derived from the attenuated Sabin strains is considered to be a highly favorable option for the production of novel IPV that reduce the risk of facility-acquired transmission of poliovirus to the communities. In Japan, Sabin-derived IPVs (sIPVs) have been developed and introduced for routine immunization in November 2012. They are the first licensed sIPVs in the world. Consequently, trivalent oral poliovirus vaccine was used for polio control in Japan for more than half a century but has now been removed from the list of vaccines licensed for routine immunization. This paper reviews the development, introduction, characterization, and global status of IPV derived from attenuated Sabin strains.
The World Health Organization Western Pacific Region (WPR) has maintained a polio-free status for more than two decades. At the global level, there were only six confirmed polio cases due to wild ...type 1 poliovirus in Pakistan, Afghanistan, and Malawi in 2021; therefore, the risk of wild poliovirus importation from endemic countries to the WPR is considerably lower than that in the past. However, the risk of polio outbreaks associated with circulating vaccine-derived polioviruses (cVDPVs) cannot be ignored even in the WPR. Since the late 2010s, cVDPV outbreaks in the WPR have increased in frequency and magnitude. Moreover, the emergence of concomitant polio outbreaks of type 1 and type 2 cVDPVs in the Philippines and Malaysia during 2019–2020 highlighted the potential risk of cVDPV outbreaks in high-risk areas and/or communities in the WPR. Previous cVDPV outbreaks in the WPR have been rapidly and effectively controlled. However, future polio outbreak risks associated with cVDPVs must be reconsidered, and polio immunization and surveillance strategies should be updated accordingly.
Powder snow avalanches and pyroclastic density currents (PDCs) are particle-gas gravity currents with stratification of particle concentrations. This paper reviews an existing two-layer PDC model and ...discusses the applicability of two-layer PDC models to powder snow avalanches. In two-layer PDC models, the upper region of PDCs is modeled as a dilute turbulent suspension flow and the lower region is modeled as a dense fluidized granular flow. Considering the interactions between these flows (e.g., particle transfer from one flow to the other), the two-layer PDC models can evaluate the flowing and stopping of PDCs. In particular, to evaluate the run-out distance of the dilute current of PDCs (i.e., the process in which the hot dilute current becomes lighter than the ambient air and lifts off the ground), the effect of thermal expansion of the ambient air entrained into the current is taken into account. Many physical processes of PDCs are common to powder snow avalanches. Unlike for PDCs, however, the run-out distance of the dilute current of the snow avalanches can be explained by the physical process of the fall-out of all particles in the dilute current due to decreased turbulent velocities in the flow. Incorporating this physical process into the two-layer PDC models may allow us to construct a unified model for powder snow avalanches and PDCs.
•The higher Hall mobility and dominant band edge emission in ZnO films with Zn polarity.•Suppressed defect formation in Zn-polarity ZnO compared to O-polarity ZnO.•High carrier density and high Hall ...mobility of Ga-doped ZnO on Zn-polar ZnO.
Herein, the influence of crystallographic polarity on the properties of ZnO polycrystalline thin films deposited by magnetron sputtering, has been studied. The electrical and optical properties of undoped ZnO and heavily Ga-doped ZnO thin films showed significant differences between Zn polarity and O polarity. The Hall mobility and carrier concentration of the undoped ZnO thin films with Zn polarity were higher than those with O polarity. The ZnO film with Zn polarity showed a dominant near-band-edge emission, while that with O polarity showed relatively intense deep-level emission in the visible wavelength region. It was suggested that acceptor-type defects tend to be formed in the ZnO films with O polarity. The Ga-doped ZnO films deposited on the Zn-polar ZnO layer showed a higher carrier concentration and Hall mobility as compared to deposition on O-polar ZnO. Crystallographic polarity is thus a very important factor for controlling the properties of polycrystalline ZnO-based thin films deposited on glass substrates.
In decision making under risk, where the consequences of choices vary depending on specific probabilities, a proper interpretation of the presented probabilities is essential. However, because people ...are not good at evaluating numerical values, such as percentages, efforts have been made to accurately convey presented probabilities using visual aids represented by icon arrays. However, previous studies have suggested that icon arrays produce an overestimation of probabilities under specific conditions. Especially, (a) the arrangement of highlighted icons and (b) the severity of the outcomes represented by highlighted icons can lead to an overestimation of probabilities. By considering the absolute estimation of probabilities indicated by icon arrays and manipulating the aforementioned factors, this study investigated whether these factors could elicit an overestimation of probabilities in an additive manner or whether they have interactive effects. Two studies (total N = 1171) consistently showed that the arrangement of highlighted icons and the outcome severity they indicate induced a perceptual bias in the estimation of the probabilities presented in icon arrays in an additive manner. When the highlighted icons were random and the outcomes they indicate were severe, the probabilities presented by the icon arrays were overestimated. Accordingly, the study not only confirms the robustness of the findings of previous studies but also expand our understanding of the probability overestimation caused by icon arrays. Here, we discuss our findings in terms of the impact of risk-related communication.
Genetically modified (GM) foods have been assumed to be seen through intuitive and affective routes (i.e., affect heuristics) rather than analytical and deliberative routes. We examined the impact of ...the graphical presentation of benefits derived from GM or conventionally bred foods on the acceptance of these varieties. In the two experiments (n = 266 for study 1 and n = 402 for study 2), no differences emerged in the estimation of farmers' benefits resulting from the introduction of improved varieties by the type of improvement. However, there were statistically significant differences in the magnitude of risk and the degree of acceptance of the improved varieties. Therefore, despite presenting identical benefits as a graphical figure, GM foods were consistently evaluated as providing higher risk and were less frequently accepted than conventionally bred foods. These results suggest that while the graphical presentation of benefits may promote comprehension of some advantages of the introduction of GM varieties, this may not lead to acceptance from the consumer's point of view. Based on the current findings, as well as previous studies on trust in risk managers, we discuss the specific factors that might promote acceptance of GM products.
A series of simulations for hydraulic fracturing in competent rock was performed by using the flow-coupled DEM code to discuss the influence of the fluid viscosity and the particle size distribution. ...The simulation results show good agreement with experimental results that contain the AE measurement data. The following observations can be made. When a low viscosity fluid is used, the fluid infiltrates into the fracture immediately. On the other hand, when a high viscosity fluid is used, the fluid infiltrates slowly into the crack after the fracture first elongates. Although tensile cracks are dominantly generated in the simulation, the energy released from a tensile crack becomes small because the tensile strength of rock is obviously small compared with the compressive strength. Such a small AE is easily buried in a noise and difficult to be measured in an experiment. Therefore, in AE measurement experiment, shear type AE with large energy is dominantly observed, as many previous researches have indicated.
► Hydraulic fracturing in hard rock was simulated by using the flow-coupled DEM. ► Crack initiation and breakdown pressure for the low viscosity fluid became low. ► Breakdown pressure in case of using a homogeneous model was remarkably high. ► Shear AE is dominant in an experiment because energy of shear crack is large.
A pyroclastic density current (PDC) is characterized by its strong stratification of particle concentration; it consists of upper dilute and lower dense currents, which generally control the dynamics ...and deposits of PDCs, respectively. To explain the relationship between the dynamics and deposits for magmatic and phreatomagmatic eruptions in a unified way, we developed a two‐layer PDC model considering thermal energy conservation for mixing of pyroclasts, external water, and air. The results show that the run‐out distance of dilute currents increases with the mass fraction of external water at the source (wmw) owing to the suppression of thermal expansion of entrained air. For wmw ∼ 0.07–0.38, the particle concentration in the dilute current becomes too low to generate the dense current so that the deposits directly form at the bottom of the dilute current in the entire area. These results capture the diverse features of natural PDCs in magmatic and phreatomagmatic eruptions.
Plain Language Summary
Explosive volcanic eruptions eject mixtures of hot fragmented magma and gas from the volcanic vent and form eruption columns, which can collapse and propagate along the ground surface as pyroclastic density currents (PDCs). The dynamics and deposits of PDCs are extremely diverse depending on the amount of external water (e.g., groundwater, lakes, and oceans) that mixes with magma. To explain the diverse features of the dynamics and deposits of PDCs for various amounts of external water, we developed a two‐layer model for PDCs considering thermal energy conservation for mixing of magma and external water. The two‐layer model successfully reproduces the dynamics and deposits of PDCs with strong stratification of particle concentrations in a unified way. The results show that the run‐out distance of upper dilute currents increases with the increasing amount of external water. For a relatively small proportion of external water, the lower dense current tends to be absent, resulting in the direct formation of the deposits from the dilute current in the entire area. These model predictions are useful to mitigate the diverse hazards caused by natural PDCs under various geological conditions.
Key Points
A two‐layer pyroclastic density current model with heat conservation for mixing of pyroclasts, external water, and air is developed
In phreatomagmatic eruptions, the upper dilute current flows over longer distances and the lower dense current tends to be absent
Our results explain the diverse features of the dynamics and deposits of natural pyroclastic density currents in a unified way
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