Michiaki Iwata

Sketch-based Dynamic Illustration of Fluid Systems

This paper presents a lightweight sketching system that enables interactive illustration of complex fluid systems. Users can sketch on a 2.5-dimensional (2.5D) canvas to design the shapes and connections of a fluid circuit. These input sketches are automatically analyzed and abstracted into a hydraulic graph, and a new hybrid fluid model is used in the background to enhance the illustrations. The system provides rich simple operations for users to edit the fluid system incrementally, and the new internal flow patterns can be simulated in real time. Our system is used to illustrate various fluid systems in medicine, biology, and engineering. We asked professional medical doctors to try our system and obtained positive feedback from them.

Consciousness Level and Off-Hour Admission Affect Discharge Outcome of Acute Stroke Patients: A J-ASPECT Study

Background Poor outcomes have been reported for stroke patients admitted outside of regular working hours. However, few studies have adjusted for case severity. In this nationwide assessment, we examined relationships between hospital admission time and disabilities at discharge while considering case severity. Methods and Results We analyzed 35 685 acute stroke patients admitted to 262 hospitals between April 2010 and May 2011 for ischemic stroke (IS), intracerebral hemorrhage (ICH), or subarachnoid hemorrhage (SAH). The proportion of disabilities/death at discharge as measured by the modified Rankin Scale (mRS) was quantified. We constructed 2 hierarchical logistic regression models to estimate the effect of admission time, one adjusted for age, sex, comorbidities, and number of beds; and the second adjusted for the effect of consciousness levels and the above variables at admission. The percentage of severe disabilities/death at discharge increased for patients admitted outside of regular hours (22.8%, 27.2%, and 28.2% for working‐hour, off‐hour, and nighttime; P<0.001). These tendencies were significant in the bivariate and multivariable models without adjusting for consciousness level. However, the effects of off‐hour or nighttime admissions were negated when adjusted for consciousness levels at admission (adjusted OR, 1.00 and 0.99; 95% CI, 1.00 to 1.13 and 0.89 to 1.10; P=0.067 and 0.851 for off‐hour and nighttime, respectively, versus working‐hour). The same trend was observed when each stroke subtype was stratified. Conclusions The well‐known off‐hour effect might be attributed to the severely ill patient population. Thus, sustained stroke care that is sufficient to treat severely ill patients during off‐hours is important.

Simulation study of complex action potential conduction in atrioventricular node

The atrioventricular (AV) node, which is located between the atria and ventricles of the heart, acts as important roles in cardiac excitation conduction between the two chambers. Although there are multiple conduction pathways in the AV node, the structure of the AV node has not been clarified. In this study, we constructed a one-dimensional model of the AV node and simulated excitation conduction between the right atrium and the bundle of His via the AV node. We also investigated several characteristics of the AV node: (1) responses of the AV node to high-rate excitation in the right atrium, (2) the AV nodal reentrant beat induced by premature stimulus, and (3) ventricular rate control during atrial fibrillation with various methods. Our simulation results suggest that multiple conduction pathways act as important roles in controlling the ventricular rate. The one-dimensional model constructed in this study may be useful to analyze complex conduction patterns in the AV node.

Simulation of ventricular rate control during atrial fibrillation using ionic channel blockers

The atrioventricular (AV) node is the only compartment that conducts an electrical impulse between the atria and the ventricles. The main role of the AV node is to facilitate efficient pumping by conducting excitation slowly between the two chambers as well as reduce the ventricular rate during atrial fibrillation (AF).

An online support system for promotion of a behavior change for persons with metabolic syndrome

The World Health Organization reported that ischemic heart disease is the most common cause of death worldwide in 2008. The main causes of ischemic heart disease are obesity, hypertension, arteriosclerosis and other metabolic abnormalities. These conditions are related to lifestyle issues, such as diet and exercise. We developed a system to support the self-management of patients using a personal digital assistant (PDA). However, diet management becomes more difficult as patient condition worsens. Both self-management and behavior change by persons with metabolic syndrome are needed to prevent ischemic heart disease. In the present study, we have improved the system to support behavior change in persons with metabolic syndrome. The system has three functions of an entry of users lifestyle information, a calculation of total amount of calorie intake and a reference to food model pictures of 80 kcal standard quantities for the behavior change. We focused on a self-review of user lifestyle as the first step of the behavior change. We conducted an experiment with the cooperation of 14 medical staff members to verify the operability of the system. No serious problems with the system were encountered. Additionally, we tested the system with health checkup examinees. The results of these tests suggested that our system will help physicians provide advice regarding total amount of calorie intake to health checkup examinees.

Feasibility for the enhancement of an online support system for persons with metabolic syndrome, aimed at applications for ischemic heart disease and heart failure

Previously, we developed of an online support system for persons with metabolic syndrome. In this study, we investigated the possibility of enhancing our system for applications in ischemic heart disease (IHD) and heart failure (HF). The main causes of IHD are obesity, hypertension, arteriosclerosis, hyperglycemia and other metabolic disorders. These conditions are related to lifestyle issues, such as diet and exercise. Dietary management becomes more difficult as the patients condition worsens. We primarily focused on behavior changes. To raise the users awareness of food intake, we improved a number of functions of the developed system: an entry of the users lifestyle information, a calculation of the total calorie intake and a reference of food model pictures in 80 kcal standard quantities. IHD encompasses many of the causes of HF. Management tools appropriate for HF are few. We describe the main functions of our system and promote self-management as a requirement for IHD and HF. We expect that the framework of our system is applicable to the management of patients with chronic HF.

A High-Speed Drug Interaction Search System for Ease of Use in the Clinical Environment

With the advancement of pharmaceutical development, drug interactions have become increasingly complex. As a result, a computer-based drug interaction search system is required to organize the whole of drug interaction data. To overcome problems faced with the existing systems, we developed a drug interaction search system using a hash table, which offers higher processing speeds and easier maintenance operations compared with relational databases (RDB). In order to compare the performance of our system and MySQL RDB in terms of search speed, drug interaction searches were repeated for all 45 possible combinations of two out of a group of 10 drugs for two cases: 5,604 and 56,040 drug interaction data. As the principal result, our system was able to process the search approximately 19 times faster than the system using the MySQL RDB. Our system also has several other merits such as that drug interaction data can be created in comma-separated value (CSV) format, thereby facilitating data maintenance. Although our system uses the well-known method of a hash table, it is expected to resolve problems common to existing systems and to be an effective system that enables the safe management of drugs.