Modeling and simulation of a Stewart platform type parallel structure robot

The kinematics and dynamics of a Stewart Platform type parallel structure robot (NASA's Dynamic Docking Test System) were modeled using the method of kinematic influence coefficients (KIC) and isomorphic transformations of system dependence from one set of generalized coordinates to another. By specifying the end-effector (platform) time trajectory, the required generalized input forces which would theoretically yield the desired motion were determined. It was found that the relationship between the platform motion and the actuators motion was nonlinear. In addition, the contribution to the total generalized forces, required at the actuators, from the acceleration related terms were found to be more significant than the velocity related terms. Hence, the curve representing the total required actuator force generally resembled the curve for the acceleration related force. Another observation revealed that the acceleration related effective inertia matrix I sub dd had the tendency to decouple, with the elements on the main diagonal of I sub dd being larger than the off-diagonal elements, while the velocity related inertia power array P sub ddd did not show such tendency. This tendency results in the acceleration related force curve of a given actuator resembling the acceleration profile of that particular actuator. Furthermore, it was indicated that the effective inertia matrix for the legs is more decoupled than that for the platform. These observations provide essential information for further research to develop an effective control strategy for real-time control of the Dynamic Docking Test System

Laboratory information management system for COVID-19 non-clinical efficacy trial data

Background : As the number of large-scale studies involving multiple organizations producing data has steadily increased, an integrated system for a common interoperable format is needed. In response to the coronavirus disease 2019 (COVID-19) pandemic, a number of global efforts are underway to develop vaccines and therapeutics. We are therefore observing an explosion in the proliferation of COVID-19 data, and interoperability is highly requested in multiple institutions participating simultaneously in COVID-19 pandemic research. Results : In this study, a laboratory information management system (LIMS) approach has been adopted to systemically manage various COVID-19 non-clinical trial data, including mortality, clinical signs, body weight, body temperature, organ weights, viral titer (viral replication and viral RNA), and multiorgan histopathology, from multiple institutions based on a web interface. The main aim of the implemented system is to integrate, standardize, and organize data collected from laboratories in multiple institutes for COVID-19 non-clinical efficacy testings. Six animal biosafety level 3 institutions proved the feasibility of our system. Substantial benefits were shown by maximizing collaborative high-quality non-clinical research. Conclusions : This LIMS platform can be used for future outbreaks, leading to accelerated medical product development through the systematic management of extensive data from non-clinical animal studies.This research was supported by the National research foundation of Korea(NRF) grant funded by the Korea government(MSIT) (2020M3A9I2109027 and 2021M3H9A1030260)

Prevention of hepatocellular carcinoma in the Asia-Pacific region: Consensus statements

Among approximately 650 000 people who die from hepatocellular carcinoma (HCC) each year, at least two-thirds live in Asia. Efforts to improve early diagnosis and treatment have not yet impacted mortality. An Asia-Pacific Working Party convened in Hong Kong in June 2008 to consider ways to prevent HCC in this region. Separate reviews have summarized epidemiology of HCC, preventive approaches related to hepatitis B virus (HBV), hepatitis C virus (HCV) and non-viral liver diseases, and the role of surveillance to detect HCC at a curative stage. We now present Consensus Statements from these deliberations and reviews. As chronic hepatitis B is the most common cause of HCC in Asia, effective hepatitis B vaccination programs are the most important strategy to reduce HCC incidence. Prevention of HCV by screening blood donors, universal precautions against blood contamination in health-care settings and reducing HCV transmission from injection drug use are also vital. There is strong evidence that effective antiviral therapy to control HBV infection or eradicate HCV substantially reduces (but does not abolish) HCC risk. With hemochromatosis, family screening, early diagnosis and correcting iron overload to prevent liver fibrosis prevents HCC. There is currently insufficient evidence to give firm recommendations on alcohol, obesity/metabolic risk factors and other liver diseases. HCC surveillance for high-risk groups is recommended in individual cases but cost-effectiveness is not as high as infant hepatitis B vaccination and screening blood for HCV. Widespread application of HCC surveillance in Asia-Pacific countries depends on economic factors and health-care priorities

Application of surveillance programs for hepatocellular carcinoma in the Asia-Pacific Region

Hepatocellular carcinoma (HCC) is a potential target for cancer surveillance (or screening) as it occurs in well-defined, at-risk populations and curative therapy is possible only for small tumors. Surveillance has been recommended by regional liver societies and is practiced widely, but its benefits are not clearly established. Hepatic ultrasonography with or without alpha fetoprotein (AFP) performed every 6 months is the preferred program. Surveillance of HCC has been well shown to detect small tumors for curative treatment, which may be translated to improved patient survival. However, most studies are limited by lead-time bias, length bias for early diagnosis of small HCC, different tumor growth rates and poor compliance with surveillance. Cost-effectiveness of surveillance programs depends on the rate of small HCC detected 'accidentally' (routine imaging) in a comparator group, annual incidence of HCC with various etiologies, patient age and the availability of liver transplantation. The incremental cost-effectiveness for 6-monthly AFP and ultrasound has been estimated from approximately $US26 000-74 000/quality adjusted life years (QALY). All cirrhotic patients are therefore recommended for HCC surveillance unless the disease is too advanced for any curative treatment. As chronic hepatitis B can develop into HCC without going through liver cirrhosis, high-risk non-cirrhotic chronic hepatitis B patients are also recommended for HCC surveillance. In conclusion, HCC surveillance could be effective at reducing disease-specific mortality with acceptable cost-effectiveness among selected patient groups, provided it is a well-organized program

Hepatocellular Carcinoma in the Asia pacific region

Primary liver cancer, particularly hepatocellular carcinoma (HCC) remains a significant disease worldwide. It is among the top three causes of cancer death in the Asia Pacific region because of the high prevalence of its main etiological agents, chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections. In this region, the incidence of HCC has been static over recent decades. Older age is a major risk factor; the incidence increasing sharply after age 40 years. There is a male predilection, with male to female ratio of 3:1, except in elderly Japanese with equal sex incidence or female predominance. In most Asia-Pacific countries, chronic HBV infection accounts for 75-80% of cases; Japan, Singapore and Australia/New Zealand are exceptions because of higher prevalence of HCV infection. In spite of advances in surgery, liver transplantation and newer pharmaco/biological therapies, the survival rate has improved only slightly over recent decades, and this could be attributable to earlier diagnosis ('lead-time bias'). The majority of patients present with advanced diseases, hence reducing the chance of curative treatment. The importance of HCC may decrease in two to three decades when the prevalence of chronic HBV infection decreases as a result of the universal HBV vaccination programs implemented in late 1980s in most Asia-Pacific countries, and because of reduced incidence of medical transmission of HCV. However, transmission of HCV by injection drug use, and rising prevalence of obesity and diabetes, both independent risk factors for HCC, may partly offset this decline

Reimbursement policies in the Asia-Pacific for chronic hepatitis B

There is considerable variation in reimbursement policies in Asian countries and this is likely to have an impact on treatment practice for chronic hepatitis B (CHB). Consequently a survey of leading hepatologists was performed to evaluate such policies and their impact on management of CHB in the Asia Pacific region