ABSTRACT
With the spread of COVID-19, the risk of droplet infection has been studied through interdisciplinary research. However, there is little information on the spread of the pathogen through human contact behavior. In this paper, we focus on the home, which is the private space of people, and propose a model to visualize the risk of contact infection to a family when people return home by combining calculation of contact behavior after returning home and study of virus transfer efficiency. First, from the contact behavior data for the first 30 minutes after returning home, we calculated the probability of flow line, the distribution of the number of contacts, the probability of initial action and the probability of contact behavior transmission. Next, we obtained the transfer efficiency between the substrate representing the household goods surface and the model skin, and the rate of change of the viral transfer efficiency when people continuously contact the household goods surface. According to these probabilities, we reproduced the state in which the virus attached to the hand or household goods surface by probabilistically performing the agent's movement and contact behavior after returning home. This result shows that when agents return home with viruses attached to their hands, the viruses are widely confirmed on household goods surfaces. Furthermore, by simulating the combination and timing of hygienic actions such as handwashing and disinfection, it was possible to visualize their effects on the risk of re-contact and care effects. © 2023, Japanese Society for Artificial Intelligence. All rights reserved.
ABSTRACT
COVID-19 infection has been reported to be caused by droplet and contact infection. This paper proposes a model that visualizes the risk of contact infection to family members when viruses spread to various items at home. Behavior data after returning home are extracted from a questionnaire-based survey of home behavior to design the agent-based model. The data tables of contact behavior are created, including the room-to-room transfer probability table, the conditional probability table, and the contact probability table. The material transfer efficiency table is also created by measuring the virus transmission rate after contact with droplets in a virus experiment laboratory. In the experiment, the synthetic agent created from the acquired data probabilistically performs movement and contact behavior after returning home and reproduces the state in which the virus attached to the hand or belongings, when going out, propagates to objects at home. Next, we examine the risk of a second family member returning home. As a result, virus-attached contacts within around 30 minutes after returning home are widely confirmed around the entrance and kitchen, suggesting the effectiveness of early hand-washing behavior. And the experiment shows that even if the first person returning home disinfects their hands inside the entrance, the virus remains in a part of the entrance, and the virus is spread inside the room by the second person returning home. Copyright © 2023 Kurahashi, Mukai, Sekine, Nakajima, Otake, Sugiyama, Takizawa and Kakizawa.
ABSTRACT
<Background> With the global epidemic of COVID-19, there has been a growing concern about the risk of exposure to the virus among healthcare workers. Gastrointestinal (GI) endoscopy has been considered as one of the high infectious procedures because of the high risk of aerosol exposure. However, that caution is mainly directed at secretions and aerosols from the patient's mouth, and less attention is currently paid to air leaks from the endoscopic system itself. Although a few reports have been published on air leaks from GI endoscopic systems, no systematic and quantitative studies of air leaks have been conducted. Schlieren system is an optical device for visualizing minute changes in airflow that are invisible to the naked eye, by using differences in the refractive index of the medium, and has been mainly used in the field of engineering. We aimed to systematically evaluate air leaks from GI endoscopic systems using Schlieren system, and to determine the relationship between the amount of leakage and insufflation conditions including the types of biopsy valves. <Methods> The following experiments were performed on explanted swine stomachs while maintaining an intra-gastric pressure at each preset value. We attempted to visualize air leaks using System Schlieren (SS100, Kato Koken, Kanagawa, Japan). In all experiments, biopsy forceps were inserted and withdrawn 3 cm per 3 seconds. This action was repeated five times in each experiment. Experiment 1: Examined the feasibility of the Schlieren device in visualizing air leaks from biopsy valves. Experiment 2: The intragastric pressure was varied in the range of 4 to 15 mmHg and the air leaks were quantified and compared in each pressure. Experiment 2: Compared the air leaks between the types of biopsy valves, e.g. reusable, disposable, universal, deteriorated reusable valves after more than 10 times of uses. Image J (National Institute of Health, US) was used to measure the initial velocity and area of the leak on obtained images. The average values of initial velocity and leakage area over five sessions were calculated. For the leak area analysis, image analysis was performed for both forceps insertion and withdrawal. <Results> Experiment 1: Air leaks were seen at the moment of forceps insertion and withdrawal (Fig 1). Experiment 2: There was a linear relationship between intragastric pressure and initial velocity/diffusion range of the leak (Fig2A). Experiment 3: Disposable and deteriorated reusable biopsy valves had larger initial velocity/diffusion range of the leak (Fig2B). <Conclusions> We successfully visualized air leaks from GI endoscopic systems using the Schlieren system. We herein recommend the use of lower intragastric pressure at the times of insertion/withdrawal of forceps, and avoidance of using disposable/deteriorated biopsy valves, for less gas leakage and possibly less aerosol exposure.(Figure presented)Figure1. Visualization of air leak from biopsy valve(Figure presented)Figure 2. Results of analysis on air leakage from biopsy valve
ABSTRACT
The influence of the COVID-19 pandemic on urban CO2 emissions was investigated using atmospheric observations in the residential area (approximately 4 x 10(5) m(2)) in Tokyo, Japan. The measured CO2 flux decreased by 20% +/- 3% in April-May 2020 compared to the same period during the past few years. The exchange ratio of O-2 and CO2 revealed the breakdown of emission sources;the decrease of flux was due to the decrease in liquid fuel consumption, while household gas fuel consumption was slightly increased;this was also supported by the simultaneously measured CO:CO2 concentration ratio. A human-activity analysis in the flux footprint area supported the results of the observation;car traffic decreased and household gas consumption increased.
ABSTRACT
Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It was first identified in December 2019 in Wuhan, China, and has resulted in global pandemic. There is currently no effective therapeutic strategy for the management of mechanical ventilation or antiviral drugs for the treatment of this disease. As such, the development of a therapeutic strategy is urgently needed and should be established as soon as possible. In this case series, a therapeutic strategy was initially developed based on previous treatment methods used for the treatment of SARS and MERS in the absence of treatment options for COVID-19 due to a lack of information. During the search for a potential treatment, clinical findings were obtained from patients with severe COVID-19, and one therapeutic strategy was established. This therapeutic strategy was then applied to severe COVID-19 patients. In addition, we can require some interesting clinical features and characteristics of COVID-19 from blood analysis and physical findings. Here, we reported on the clinical features and characteristics of a therapeutic strategy for the treatment of severe COVID-19 pneumonia at our institution.