Background. The purpose of this study was to determine the rate of vertical transmission of hepatitis C virus (HCV). We also aimed to analyze the time of clearance of maternal antibodies in the serum of non-infected babies. Methods. Between March 1990 and March 2000, 170 consecutive anti-HCV-positive women and their 188 babies entered this prospective study. All women were analyzed for HCV-RNA using polymerase chain reaction (PCR). The babies were followed-up until HCV-antibody clearance or until the diagnosis of HCV infection. Results. The vertical transmission rate was 2.7% overall, and it was higher in HIV co-infected women (5.4%, 2/37) than in HIV-negative women (2.0%, 3/151). All infected infants were born to mothers who had HCV viremia at delivery. The transmission rate was influenced by maternal levels of viremia. 37.2% of uninfected children became HCVantibody negative by 6 months and 88.0% by 12 months. Babies born from HCV-RNApositive mothers lost anti-HCV antibodies later (9.21 AE 3.72 months) than babies born from HCV-RNA-negative mothers (7.47 AE 3.46 months) (p < 0.05, Kolmogorov-Smirnov test). Conclusions. The risk of HCV vertical transmission is very low in HCV-positive/HIVnegative women and it is restricted to infants born to HCV viremic mothers. High maternal viral load is predictive of the vertical transmission. The clearance time of antibodies in non-infected babies is significantly longer if the mother is viremic.

This paper presents a novel approach to content delivery for video streaming services. It exploits information from connected eye-trackers embedded in the next generation of VR Head Mounted Displays (HMDs). The proposed solution aims to deliver high visual quality, in real time, around the users' fixations points while lowering the quality everywhere else. The goal of the proposed approach is to substantially reduce the overall bandwidth requirements for supporting VR video experiences while delivering high levels of user perceived quality. The prerequisites to achieve these results are: (1) mechanisms that can cope with different degrees of latency in the system and (2) solutions that support fast adaptation of video quality in different parts of a frame, without requiring a large increase in bitrate. A novel codec configuration, capable of supporting near-instantaneous video quality adaptation in specific portions of a video frame, is presented. The proposed method exploits in-built properties of HEVC encoders and while it introduces a moderate amount of error, these errors are indetectable by users. Fast adaptation is the key to enable gaze-aware streaming and its reduction in bandwidth. A testbed implementing gaze-aware streaming, together with a prototype HMD with in-built eye tracker, is presented and was used for testing with real users. The studies quantified the bandwidth savings achievable by the proposed approach and characterize the relationships between Quality of Experience (QoE) and network latency. The results showed that up to 83% less bandwidth is required to deliver high QoE levels to the users, as compared to conventional solutions.

No abstract

QoE-aware optimization for video delivery and storage. In: 2015 IEEE 16th International Symposium on "A World of Wireless, Mobile and MultimediaNetworks" (WoWMoM) 2015 (pp. 1-10 Abstract-The explosive growth of Over-the-top (OTT) online video strains capacity of operators' networks, which severely threatens video quality perceived by end users. Since video is very bandwidth consuming, its distribution costs are becoming too high to scale with network investments that are required to support the increasing bandwidth demand. Content providers and operators are searching for solutions to reduce this video traffic load, without degrading their customers' perceived Quality of Experience (QoE). This paper proposes a method that can programmatically optimize video content for desired QoE according to perceptual video quality and device display properties, while achieving bandwidth and storage savings for content providers, operators, and end users. The preliminary results obtained with Samsung Galaxy S3 phone show that up to 60% savings can be achieved by optimizing movies without compromising the perceptible video quality, and up to 70% for perceptible, but not annoying video quality difference. Tailoring video optimization to individual user perception can provide seamless QoE delivery across all users, with a low overhead (i.e., 10%) required to achieve this goal. Finally, two applications of video optimization: QoE-aware delivery and storage, are proposed and examined.

No abstract