114 research outputs found
Esophagogastroduodenoscopy Screening Intentions During the COVID-19 Pandemic in Japan: Web-Based Survey
No full textBACKGROUND: The number of people undergoing cancer screening decreased during the COVID-19 pandemic. The pandemic may have affected the willingness and motivation of undergoing cancer screening by those eligible for it. OBJECTIVE: This study aims to clarify the effect of the COVID-19 pandemic on the intention to undergo cancer and esophagogastroduodenoscopy (EGD) screening. METHODS: We performed a web-based survey on the intention to undergo screening among 1236 men and women aged 20-79 years. The numbers of participants by sex and 10-year age groups were equal. The survey was conducted in January 2021, during which the government declared a state of emergency because of the third wave of the COVID-19 pandemic in Japan. Emergency declarations were issued in 11 prefectures among all the 47 prefectures in Japan. RESULTS: In total, 66.1% (817/1236) of the participants felt anxious about undergoing screening due to COVID-19. More women than men were anxious about undergoing screening. By modality, EGD had the highest percentage of participants with anxiety due to COVID-19. Regarding the intention to change the participants’ appointment for screening, the most common strategies were to book an appointment for a time during nonpeak hours, postpone the appointment to a later date, and change the mode of transportation. In addition, 35.8% (442/1236) of the participants were willing to cancel this year’s screening appointment. Among the 1236 participants, 757 (61.2%) were scheduled for screening in 2020. Of the 757 participants in this subgroup, 68% (n=515) did not change the schedule, 6.1% (n=46) cancelled, and 26% (n=197) made some changes, including changing the appointment date, hospital, or mode of transportation. Among the 296 participants scheduled for EGD screening, 18.9% (n=56) made some changes, 5.7% (n=17) cancelled on their own, and 2.7% (n=8) cancelled on the hospital’s order. Based on the previous screening results, the percentage of participants who felt anxious about EGD due to the COVID-19 pandemic was higher in the order of those who had not undergone screening and those who were judged to be in need of further examination in screening but did not visit a hospital for it. In the logistic regression analysis, the factors associated with anxiety about EGD screening due to the COVID-19 pandemic were “viral infection prevention measures,” “waiting time,” “fees (medical expenses),” “mode of transportation,” “worry about my social position if I contracted COVID-19,” and “perceived the risk of gastric cancer.” However, “residence in declared emergency area” was not associated with EGD anxiety due to COVID-19. CONCLUSIONS: Excessive anxiety about COVID-19 may lead to serious outcomes, such as a “decreasing intention to undergo EGD screening,” and it is necessary to thoroughly implement infection prevention measures and provide correct information to examinees
Microscopic Observations of Freezing Phenomena in PEM Fuel Cells at Cold Starts
No full textIn Polymer electrolyte membrane fuel cells (PEMFCs), the generated water transfers from the catalyst layer to the gas channel through micro channels of different scales in a two phase flow. It is important to know details of the water transport phenomena to realize better cell performance, as the water causes flooding at high current density conditions and give rise to startup problems at freezing temperatures. This paper here, which was originally written for the keynote speech in the ICNMM conference in 2011, presents specifics of the ice formation characteristics in the catalyst layer and in the gas diffusion layer (GDL) with photos taken with an optical microscope and a CRYO-SEM. The observation results show that cold starts at -10℃ results in ice formation at the interface between the catalyst layer and the micro porous layer (MPL) of the GDL, and that at -20℃ most of the ice is formed in the catalyst layer. Water transport phenomena through the micro porous layer and GDL are also a matter of interest, because the role of the MPL is not well understood from the water management angle. The paper discusses the difference in the water distribution at the interface between the catalyst layer and the GDL arising from the presence of such a micro porous layer
Supporting safe motherhood : a review of financial trends : summary
No full textAn estimated 500,000 women, 99 percent of them from the developing world, die each year from pregnancy-related causes. About three quarters of these deaths are the direct result of obstetrical complications -- hemorrhage, infection, toxemia, obstructed labor, and abortion (under primitive and illegal conditions). An estimated equivalent number of infants do not survive their mother's death. For surviving mothers, the consequences of pregnancy have a severe impact on health and family economics. The strategy for safe motherhood is based on two approaches. First, the encouragement of activities that indirectly improve maternal health. These include education, policies to improve women's rights and working conditions, health care and nutrition, transportation and communication systems, water and sanitation facilities, and increases in family income and food production. The second approach targets activities to reduce maternal deaths. These activities include reducing unwanted pregnancies through the provision of family planning services, and through national policies that recognize the importance of this issue. A second objective is to reduce the risks of pregnancy through providing community-based family planning and prenatal services to identify high-risk cases'adequate referral services for the complications of pregnancy, and communication and transport systems to support patient referral procedures.Health Monitoring&Evaluation,Health Systems Development&Reform,Gender and Health,Early Child and Children's Health,Agricultural Knowledge&Information Systems
Performance and liquid water distribution in PEFCs with different anisotropic fiber directions of the GDL
No full textTo maintain the efficiency of proton exchange membrane fuel cells (PEFC) without flooding, it is necessary to control the liquid water transport in the gas diffusion layer (GDL). This experimental study investigates the effects of the GDL fiber direction on the cell performance using an anisotropic GDL. The results of the experiments show that the efficiency of the cell is better when the fiber direction is perpendicular to the channel direction, and that the cells with perpendicular fibers are more tolerant to flooding than cells with fibers parallel to the channel direction. To determine the mechanism of the fiber direction effects, the liquid water behavior in the channels was observed through a glass window on the cathode side. The observations substantiate that the liquid water produced under the ribs is removed more smoothly with the perpendicular fiber direction. Additionally, the water inside the GDL was frozen to observe its distribution using a specially made cell broken into two pieces. The photographic results show that the amount of water under the ribs is larger than that under the channels using the parallel fiber direction GDL while the water distributions in these two places are almost equal level with the perpendicular fiber direction GDL. This freezing method confirmed the better liquid water removal ability and better reactant gas transportation in the GDL with the fiber direction perpendicular to the channel direction
Numerical simulation of liquid water and gas flow in a channel and a simplified gas diffusion layer model of polymer electrolyte membrane fuel cells using the lattice Boltzmann method
No full textNumerical simulations using the lattice Boltzmann method (LBM) are developed to elucidate the dynamic behavior of condensed water and gas flow in a polymer electrolyte membrane (PEM) fuel cell. Here, the calculation process of the LBM simulation is improved to extend the simulation to a porous medium like a gas diffusion layer (GDL), and a stable and reliable simulation of two-phase flow with large density differences in the porous medium is established. It is shown that dynamic capillary fingering can be simulated at low migration speeds of liquid water in a modified GDL. and the LBM simulation reported here, which considers the actual physical properties of the system, has significant advantages in evaluating phenomena affected by the interaction between liquid water and air flows. Two-phase flows with the interaction of the phases in the two-dimensional simulations are demonstrated. The simulation of water behavior in a gas flow channel with air flow and a simplified GDL shows that the wettability of the channel has a strong effect on the two-phase flow. The simulation of the porous separator also indicates the possibility of controlling two-phase distribution for better oxygen supply to the catalyst layer by gradient wettability design of the porous separator
Two phase flow simulation in a channel of a polymer electrolyte membrane fuel cell using the lattice Boltzmann method
No full textWater management in polymer electrolyte (PEM) fuel cells is important for fuel cell performance and durability. Numerical simulations using the lattice Boltzmann method (LBM) are developed to elucidate the dynamic behavior of condensed water and gas flows in a polymer electrolyte membrane (PEM) fuel cell gas channel. A scheme for two-phase flow with large density differences was applied to establish the optimum gas channel design for different gas channel heights, droplet positions, and gas channel walls wettability. The present simulation using the LBM, which considers the actual physical properties of the system, shows the effect of the cross-sectional shape, the droplet initial position, droplet volume and the air flow velocity for both hydrophobic and hydrophilic gas channels. The discussion of optimum channel height and drain performance was made using two factors "pumping efficiency" and "drainage speed". It is shown that deeper channels give better draining efficiency than shallower channels, and the efficiency remains largely unchanged when the droplet touches corners or the top of walls in the gas channel. As the droplet velocity, i.e. the drainage flow rate, becomes higher and the drainage efficiency becomes less dependent on droplet locations with shallower channels, shallower channels are better than deeper channels as the pumping efficiency is not greatly affected. Introducing a new dimensionless parameter, "pumping efficiency", the investigation discusses the effect of the various parameters on the drainage performance of a PEM fuel cell gas channel
Experimental economics and small decision-making problems
No full textThis thesis aims at pursuing an extensive investigation into decision making in small decision-making problems with the tool of experimental economics. A typical small decision-making problem is characterised by three critical features: first, it involves repeated tasks; the decision maker faces the same choice problem many times in similar situations. Second, each single choice is of little consequence in terms of net payoff; the alternatives tend to have similar expected value that may be fairly small. Finally, in choosing among the possible alternatives, the decision maker will have to rely on the immediate and unbiased feedback obtained in similar situations in the past. The importance of shedding light on the economics of small decisions is twofold. The first is that nowadays many common economic activities can be captured by small decision-making problems. Second, although each small decision conducted by the decision maker is not very important, the aggregate outcomes may be consequential and significant when repeated. In the first place, the author of this thesis deals with the question of propensities for individual decision making in small decision-making problems. To elicit an answer to the question, a series of economics experiments are conducted. The author identifies the ideas behind individual decision making in small decision making problems and assesses the observed outcomes. A substantial work of this thesis is based on the two experiments presented in this thesis: (1) the search experiment, and (2) the choice experiment. Among the results is the demonstration that in the search experiment the tendency to select best reply to the past and mis-estimation of the payoff distribution leads to robust deviations from maximisation. As for the choice experiment, it raises a discussion on appropriateness of the certainty effect in repeated-play decisions. I present the expected utility model, which shows even in small decision-making problems the certainty effect is appropriate. As well as the search and the choice experiment, this thesis conducts the ambiguity treatment experiment. The experiment includes the situation where the decision maker’s payoff distribution is limited to either favourable distribution or unfavourable distribution. Results are analysed in the context of Bayesian updating. The first observation reveals loss aversion. The second observation includes the law of small numbers and deviations from maximisation. Finally, imperfect Bayesians are observed in the experiment. . Having finished fundamental analysis on small decision-making problems, I analyse a practical application of small decision-making problems and attempts to explain the observations in terms of the theory and experiments. It deals with the question of why a case of small decision-making problems is significant in our daily life. One practical application of small decision-making problems is concerned with individual officer’s petty corrupt behaviour. I experimentally examine that it is caused by subjective underweighting of rare events and its objective probabilities. Results of an experiment reveal that the subjects tend to subjectively underweight rare outcomes in small decision-making problems. It is revealed that petty corrupt behaviour is a consequence of the theoretically-optimal behaviour. This is examined along with the expected utility model. Another practical application of small decision-making problems is concerned with a model of educational efforts in the context of individual learning in small decision-making problems. I will show that an individual student’s optimal investment in education is shown to depend on what other students are doing. On the basis of this simple model, I establish how herding can influence the economic decision making into the formation of human capital: these important individual decisions may be predicated upon collective “whims” and “fashions” and not longrun economic consequences. I also offer a model of product quality in a simple duopoly as one of applications of small decision-making problems. I exploit the full-cost pricing models. Based on these two key features, I derive the dynamics that characterise the evolution of product quality. This thesis presents that duopolists retain and invoke a signal of quality of the items. A series of signals are discussed and investigated in the light of small decision-making problems
Cold start characteristics and freezing mechanism dependence on start-up temperature in a polymer electrolyte membrane fuel cell
No full textCold start characteristics of a polymer electrolyte membrane fuel cell are investigated experimentally, and microscopic observations are conducted to clarify the freezing mechanism in the cell. The results show that the freezing mechanism can be classified into two types: freezing in the cathode catalyst layer at very low temperature like -20℃. and freezing due to supercooled water at the interface between the catalyst layer and the gas diffusion layer near 0℃ like -10℃. The amount of water produced during the cold start is related to the initial wetness condition of the polymer electrolyte membrane, because water absorption by the membrane due to back diffusion plays an important role to prevent the water from freezing. It is also shown that after the shutdown of the cold start the cell performance of a subsequent operation at 30℃ is temporarily deteriorated after the freezing at -10℃, but not after the freezing at -20℃. The ice formed at the interface between the catalyst layer and the gas diffusion layer is estimated to cause the temporary deterioration, and the function of a micro porous layer coating the gas diffusion layer for the ice formation is also discussed
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