Statistics and vertical directionality of low-frequency ambient noise at the North Pacific Acoustic Laboratory site.

We examine statistical and directional properties of the ambient noise in the 10-100 Hz frequency band from the NPAL array. Marginal probability densities are estimated as well as mean square levels, skewness and kurtoses in third octave bands. The kurotoses are markedly different from Gaussian except when only distant shipping is present. Extremal levels reached approximately 150 dB re 1 micro Pa, suggesting levels 60dB greater than the mean ambient were common in the NPAL data sets. Generally, these were passing ships. We select four examples: i) quiescent noise, ii) nearby shipping, iii) whale vocalizations and iv) a micro earthquake for the vertical directional properties of the NPAL noise since they are representative of the phenomena encountered. We find there is modest broadband coherence for most of these cases in their occupancy band across the NPAL aperture. Narrowband coherence analysis from VLA to VLA was not successful due to ambiguities. Examples of localizing sources based upon this coherence are included. kw diagrams allow us to use data above the vertical aliasing frequency. Ducted propagation for both the quiescent and micro earthquake (T phase) are identified and the arrival angles of nearby shipping and whale vocalizations. MFP localizations were modestly successful for nearby sources, but long range ones could not be identified, most likely because of signal mismatch in the MFP replica.

Measles vaccine coverage and immune response in children of Caiabi and Metuktire Indian tribes living in malarial endemic area: Parque indígena do Xingu, Central Brazil.

Measles vaccination efficiency was evaluated in children from two Indian tribes - Caiabi and Metuktire - living in the Amazon region, in the Parque Indigena do Xingu (PIX). The population sample, selected at random, made up 37 Caiabi and 28 Metuktire children, aged from 20-75 months (40%). For operational and epidemiological reasons, measles vaccine is given from 6 months of age. The average age of children when they received the vaccine was 11.5 months for the first dose and 20 months for the second. The search for IgG antibodies against measles virus and Plasmodium falciparum was made through immunofluorescence assay (IFA). Measles vaccine coverage has reached 60% at 12 months of age and 92% at 18 months, whereas post-vaccine serum conversion was 95% in Caiabi children (geometric mean of titres (GMT) 126) and 89% in Metuktire (GMT 109). The difference in GMT is not statistically significant. Seventy-three per cent of Caiabi children (GMT 101) and 100% of Metuktire children (GMT135) were plasmodium antibody positive, showing they had been exposed to malarial infection. Despite the differences detected, the immune response to measles vaccine was satisfactory in both groups, with a positive percentage consistent with that achieved in non-malarial areas in Americas. The results show the efficiency of a vaccination programme in an indigenous area despite the difficulties in reaching the villages and maintaining the cold chain, and also despite the malaria endemicity.