The problem of the generation of an intermediate image between two given images in an image sequence is considered. The problem is formulated as an optimal control problem governed by a transport equation. This approach bears similarities with the Horn & Schunck method for optical flow calculation but in fact the model is quite different. The images are modelled in BV and an analysis of solutions of transport equations with values in BV is included. Moreover, the existence of optimal controls is proven and necessary conditions are derived. Finally, two algorithms are given and numerical results are compared with existing methods. The new method is competitive with state-of-theart methods and even outperforms several existing methods.

High prevalence of syphilis and overlapped unprotected commercial sex and drug using behaviors among FSWs along a drug-trafficking route may suggest a potential for rapid spread of HIV from injection drug users to FSWs and then to the general population and underscore the urgency of preventive interventions to break the bridge of FSWs for HIV/sexually transmitted disease spread.

No abstract

Blood-borne infections continue to spread, but at lower rates with time among IDU in a southwestern Chinese city where intervention programmes have existed for a few years. Rigorous implementation of harm reduction programmes may have reduced seroconversion to blood-borne infections among targeted high-risk populations.

Motivated by Google’s technology specifications on Android devices, we consider firms’ decisions on production timing in a co‐opetitive supply chain comprising a manufacturer and an original equipment manufacturer (OEM), where the manufacturer acts as the OEM’s upstream contract manufacturer and downstream competitor. We consider the market acceptance uncertainty of key product designs. If a firm decides to implement ex post production strategy (PS), it can delay the production until the market acceptance uncertainty of its product is resolved. Otherwise, ex‐ante production strategy (AS) is implemented. We find that, due to the co‐opetition, PS does not always benefit either the manufacturer or the OEM, because the value of delayed production is diminished as the competitor may commit a production quantity earlier under AS. Further, firms’ decisions on production timing are dependent on the degree of market acceptance uncertainty of their products and competition intensity. We find that both firms choose PS when uncertainty is high, while only one of them chooses PS when uncertainty is moderate or low. Interestingly, when the competition is intense, the manufacturer tends to choose PS, which can benefit from both the resolved market acceptance uncertainty and OEM’s early commitment of production quantity.

The results of this study suggested total times of sharing injection equipment in the past 3 months and syphilis infection were significantly associated with HIV infection. Further seroepidemiologic prospective cohort studies should be conducted to clarify the impact of syphilis and high-risk sexual behaviors on HIV transmission through unprotected sexual intercourse.

HIV-1 seroconversion and subtype were evaluated, and factors associated with cohort retention were analyzed for subjects' baseline sociodemographic and behavioral characteristics in a 12-month follow-up study of injection drug users (IDUs). In November 2002, a community-based baseline survey was conducted to recruit 333 HIV-seronegative IDUs for a prospective cohort study in Xichang County of Sichuan Province, China. During the 12-month follow-up period, HIV incidence was 3.17 per 100 person-years (95% confidence interval [CI]: 0.98, 5.37), and all subtypes of 8 HIV-1 seroconversions were CRF_07BC. The retention rate at the 12-month follow-up visit was 70.3% (234 of 333 subjects). In a multiple logistic regression model, ethnicity (OR = 0.60, 95% CI: 0.34, 1.04) and appearing at the 6-month follow-up visit (OR = 9.03, 95% CI: 5.14, 15.89) were independently associated with retention. No drug-using or sexual behaviors were found to be associated with retention. This study confirmed one of drug-trafficking routes in mainland China, from Yunnan to Sichuan and then to Xinjiang. This study also suggested that HIV is spreading rapidly to more geographic areas along drug-trafficking routes in China, and a short-term follow-up rate may predict a long-term retention rate in this IDU cohort.

Shared needles and syringes in the past 3 mo and syphilis infection were significantly associated with HCV infection. Further sero-epidemiological prospective cohort studies should be conducted to clarify the impact of syphilis and high risk sexual behaviors on HCV transmission through unprotected sexual intercourse.