Acoustic environment identification by Kullback-Leibler divergence.

This paper presents a forensic methodology that determines, from among a set of recording places, the probable place where allegedly a disputed digital audio recording was made. The methodology considers that digital audio recordings are noisy signals that have two involved noise components. One component is the multiplicative noise, which is an internal feature on the audio recording that is related to the recording device. The other component is the additive noise, which is an external feature on the audio recording that can be related to the recording place. Therefore, the proposed methodology estimates a likelihood rate that helps to decide which recording place is more plausible to be associated with a disputed audio recording. This likelihood rate is defined as the probability of a finding, supposing that a specific proposition is true, divided by the probability of a finding if an alternative proposition is true. Such probabilities are calculated by performing a statistical comparison through the Kullback-Leibler divergence [1], between the probability distribution function of the additive noise associated to the disputed recording and the probability distribution function of the additive noises associated to a set of audio recordings made on the possible recording places. Then, in order to determine the recording place, the analyst requires a list of possible places where the recording could have been carried out; in these places some reference recordings will be made. In this work, the additive noise is estimated by the Geometric Approach to Spectral Subtraction (GA-SS) filter [2], applied to the noisy audio recording.

[Advanced maternal age and pregnancy: how much is too much?]. / Edad materna avanzada y embarazo: qué tanto es tanto?

Perinatal evolution was compared and two study groups in women with advanced maternal age and pregnancy. 626 were included from a total of 778 with age 35 years, who resolved their pregnancy during 1995. They were classified, according to age, in two groups: 1) maternal age of 35-39 year; they were considered primigestas and multigestas. Perinatal complications were classified in personal antecedent, antepartum and intrapartum complications. To analyze the association between maternal age and parity with perinatal complications, X2 or exact test of Fisher, was used. Percentage of women with advanced age and pregnancy was 13.6%. Main perinatal complications were: preeclapmsia, gestational diabetes, preterm delivery threat, and membranes rupture. There were no significant differences as to complications by age and parity. There were 90% of children with 2500 g, and Apgar of 97%. Perinatal death was 0.4%, and fetal malformation 0.6%. Cesarean frequency, was over 90% in primigestas and in more of 60% in multigestas. Perinatal evolution in advanced age and pregnancy is adequate, if she starts prenatal control early enough.