Estimation and Projection of the HIV Epidemic Trend among the Migrant Population in China

Objective The migrant population is a vulnerable group for HIV infection in China.Understanding potential epidemic trends among migrants is critical for developing HIV preventative measures in this population.Methods The Estimation and Projection Package （EPP） model was used to process prefecture and county-level surveillance data to generate HIV prevalence and epidemic trends for migrant populations in China.Results The prevalence of HIV among migrants in 2009 was estimated at 0.075% （95% CI：0.042%,0.108%） in China.The HIV epidemic among migrants is likely to increase over the next 5 years,with the prevalence expected to reach 0.110% （95% CI：0.070%,0.150%） by 2015.Conclusion Although the 2009 estimates for the HIV/AIDS epidemic in China indicate a slower rate of increase compared with the national HIV/AIDS epidemic,it is estimated to persistently increase among migrants over the next 5 years.Migrants will have a strong impact on the overall future of the HIV epidemic trend in China and evidence-based prevention and monitoring efforts should be expanded for this vulnerable population.

A NOVEL DIRECTION OF ARRIVAL ESTIMATOR

A Direction Of Arrival(DOA) estimator based on the signal separation principle is introduced, and one of representative multidimensional estimators is established by introducing Matrix Operator projection signal steering Vector Excision(MOVE) operation. Thanks to Alternating Separation (AS) technique, the multidimensional problem is transformed into a series of one-dimensional optimal ones. Furthermore, an equivalent simplified implementation of the AS is obtained. Finally the definiteness and uniqueness of the estimator are analyzed.

Nonparametric VSS-APA based on precise background noise power estimate

The adaptive algorithm used for echo cancellation(EC) system needs to provide 1) low misadjustment and 2) high convergence rate. The affine projection algorithm(APA) is a better alternative than normalized least mean square(NLMS) algorithm in EC applications where the input signal is highly correlated. Since the APA with a constant step-size has to make compromise between the performance criteria 1) and 2), a variable step-size APA(VSS-APA) provides a more reliable solution. A nonparametric VSS-APA(NPVSS-APA) is proposed by recovering the background noise within the error signal instead of cancelling the a posteriori errors. The most problematic term of its variable step-size formula is the value of background noise power(BNP). The power difference between the desired signal and output signal, which equals the power of error signal statistically, has been considered the BNP estimate in a rough manner. Considering that the error signal consists of background noise and misalignment noise, a precise BNP estimate is achieved by multiplying the rough estimate with a corrective factor. After the analysis on the power ratio of misalignment noise to background noise of APA, the corrective factor is formulated depending on the projection order and the latest value of variable step-size. The new algorithm which does not require any a priori knowledge of EC environment has the advantage of easier controllability in practical application. The simulation results in the EC context indicate the accuracy of the proposed BNP estimate and the more effective behavior of the proposed algorithm compared with other versions of APA class.