Epidemiology and natural history of hepatitis C virus infection

Hepatitis C virus(HCV)affects 130-210 million people worldwide and is one of the major risk factors for hepatocellular carcinoma.Globally,at least one third of hepatocellular carcinoma cases are attributed to HCV infection,and 350000 people died from HCV related diseases per year.There is a great geographical variation of HCV infection globally,with risk factors for the HCV infection differing in various countries.The progression of chronic hepatitis C to end-stage liver disease also varies in different study populations.A long-term follow-up cohort enrolling participants with asymptomatic HCV infection is essential for elucidating the natural history of HCV-caused hepatocellular carcinoma,and for exploring potential seromarkers that have high predictability for risk of hepatocellular carcinoma.However,prospective cohorts comprising individuals with HCV infection are still uncommon.The risk evaluation of viral load elevation and associated liver disease/cancer in HCV(REVEAL-HCV)study has followed a cohort of 1095 residents seropositive for antibodies against hepatitis C virus living in seven townships in Taiwan for more than fifteen years.Most of them have acquired HCV infection through iatrogenic transmission routes.As the participants in the REVEALHCV study rarely receive antiviral therapies,it provides a unique opportunity to study the natural history of chronic HCV infection.In this review,the prevalence,risk factors and natural history of HCV infection are comprehensively reviewed.The study cohort,data collection,and findings on liver disease progression of the REVEAL-HCV study are described.

Load Assessment of the Static Posture and Weight Holding inTerms of Pulmonary Ventilation and Heart Rate

The aim of this study was to explore appropriate index for load evaluation by analyzing.the changes of pulmonary ventilation (VE) and heart rate (HR)in 35 student volunteers under the condition of static posture and weight holding.Each subject was asked to perform 7 kinds of static postures and 2 kinds of weight holdings. The HR was continuously measured by a remote detecting device. VE was recorded by a ventimeter for an average of 5 min. The results showed that HR was positively correlated to VE under static activities (r=0. 89), which suggested that VE as well as HR could to some degrees reflect the static load. It was better to use VE to indicate the load of weight holdings than to use HR, which, on the other hand, was more sensible in reflection of the posture load. It is better to use relative value of both of VE and HR to reflect the static load. In addition,arm-overheaded posture increase HR more significantly than any other activities.

Digital Beamforming by Multiple Chirp Zeta Transforms for 3-D Sonar Imaging Systems

The computational load is prohibitive for real-time image generation in 3-D sonar systems, particularly when the steering angle approximation is required. In this paper, a novel multiple Chirp Zeta Transforms （MCZT） beamforming method in frequency domain is being proposed. The single long-length Chirp Zeta Transform （CZT） in the original CZT beamforming is replaced by several CZTs with smaller lengths for different partitions along each dimension. The implementing routine of the algorithm is also optimized. Furthermore, an avenue to evaluate the estimating error for the angle approximation in 3-D imaging applications is presented, and an approach to attain valid partitions for the steering angles is also flhistrated. This paper demonstrates a few advantages of the proposed frequency-domain beamforming method over existing methods in terms of the computatianal complexity.