Decoding with confidence: Statistical control on decoder maps.

In brain imaging, decoding is widely used to infer relationships between brain and cognition, or to craft brain-imaging biomarkers of pathologies. Yet, standard decoding procedures do not come with statistical guarantees, and thus do not give confidence bounds to interpret the pattern maps that they produce. Indeed, in whole-brain decoding settings, the number of explanatory variables is much greater than the number of samples, hence classical statistical inference methodology cannot be applied. Specifically, the standard practice that consists in thresholding decoding maps is not a correct inference procedure. We contribute a new statistical-testing framework for this type of inference. To overcome the statistical inefficiency of voxel-level control, we generalize the Family Wise Error Rate (FWER) to account for a spatial tolerance δ, introducing the δ-Family Wise Error Rate (δ-FWER). Then, we present a decoding procedure that can control the δ-FWER: the Ensemble of Clustered Desparsified Lasso (EnCluDL), a procedure for multivariate statistical inference on high-dimensional structured data. We evaluate the statistical properties of EnCluDL with a thorough empirical study, along with three alternative procedures including decoder map thresholding. We show that EnCluDL exhibits the best recovery properties while ensuring the expected statistical control.

Knowledge and practice on HIV/AIDS infection prevention of public security cadres policemen in Hanoi

Study on 290 policemen in Hanoi suggested that almost policemen (96.9%) believed that HIV/AIDS is preventable. The policemen who had knowledge to avoid getting HIV from illegal drug users and HIV/AIDS patients were at a high rate (>90%) but the rate of full knowledge about HIV/AIDS was still low (82.1%). The source of information mainly came from media: television (97.6%), newspaper (92.8%) and radio (83.4%). Almost policemen often had to get in touch with criminal persons (92.8%). 66.7% of them did not knew criminal persons with HIV/AIDS and 39.1% of policemen exposed with blood and body fluid of criminal persons due to trying arrest them. After exposing, most of policemen used themselves anti-infection chemical (56.6%) or did not be treated at all (43.4%). The rate of HIV/AIDS protection equipment was very low (22.8%). The main equipment is rubber gloves (87%).