Across-Channel Timing Differences as a Potential Code for the Frequency of Pure Tones

When a pure tone or low-numbered harmonic is presented to a listener, the resulting travelling wave in the cochlea slows down at the portion of the basilar membrane (BM) tuned to the input frequency due to the filtering properties of the BM. This slowing is reflected in the phase of the response of neurons across the auditory nerve (AN) array. It has been suggested that the auditory system exploits these across-channel timing differences to encode the pitch of both pure tones and resolved harmonics in complex tones. Here, we report a quantitative analysis of previously published data on the response of guinea pig AN fibres, of a range of characteristic frequencies, to pure tones of different frequencies and levels. We conclude that although the use of across-channel timing cues provides an a priori attractive and plausible means of encoding pitch, many of the most obvious metrics for using that cue produce pitch estimates that are strongly influenced by the overall level and therefore are unlikely to provide a straightforward means for encoding the pitch of pure tones

Estado nutricional de crianças assistidas em creches e situação de (in)segurança alimentar de suas famílias Nutritional status of children attended in day-care-centers and food (in)security of their families

Examinar fatores associados a excesso de peso, déficit de estatura e déficit de peso em crianças assistidas em creches estaduais de João Pessoa e descrever a situação de (in)segurança alimentar das suas famílias. Trata-se de um estudo transversal com amostra de 250 crianças. Foram estudadas variáveis socioeconômicas, maternas e das crianças. O estado nutricional das crianças foi avaliado considerando os índices estatura-para-idade e peso-para-estatura. A segurança alimentar familiar foi avaliada com a utilização da Escala Brasileira de Insegurança Alimentar. As proporções de déficit de estatura, déficit de peso e excesso de peso foram 7,6%, 1,6% e 6,4%, respectivamente. Os fatores associados à baixa estatura foram baixa estatura materna e esquema vacinal incompleto. Com relação ao baixo peso, o fator associado foi idade materna inferior a 20 anos. O excesso de peso infantil apresentou associação com o excesso de peso materno e baixa estatura materna. Em 59,6% das famílias, observou-se situação de insegurança alimentar e nutricional, sendo mais frequente a forma leve (32,4%). Excesso de peso e déficit de estatura foram os distúrbios nutricionais mais frequentes neste estudo, constituindo prioridades que devem ser consideradas nas políticas públicas atuais.<br>The scope of this study was to examine associated factors with overweight, stunting and underweight in children attending state day care centers of João Pessoa, as well as to describe the situation of food (in)security of their families. A cross-sectional study was conducted with a sample of 250 children. Socioeconomic, maternal and child variables were studied. The nutritional status of children was evaluated considering the height-for-age and weight-for-height indices. Household food security was assessed using the Brazilian Scale of Food Insecurity. The proportions of stunting, underweight and overweight were 7.6%, 1.6% and 6.4% respectively. The associated factors with short stature were low maternal stature and incomplete vaccination. In relation to low weight, the associated factor was maternal age under 20 years. The overweight child was associated with excessive maternal weight and maternal short stature. In 59.6% of families, there was food and nutrition insecurity, the mild form being more frequent (32.4%). Overweight and stunting were found to be the most common nutritional disorders in this study, constituting priorities that should be considered in current public policies